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Luo YH, Li WHC, Cheung AT, Ho LLK, Xia W, He XL, Zhang JP, Chung JOK. Relationships between resilience and quality of life in parents of children with cancer. J Health Psychol 2021; 27:1048-1056. [PMID: 33522296 DOI: 10.1177/1359105321990806] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
CLINICALTRIALS.GOV ID NCT03631485.
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Affiliation(s)
- Y H Luo
- University of Hong Kong, Hong Kong
| | - W H C Li
- University of Hong Kong, Hong Kong
| | | | - L L K Ho
- University of Hong Kong, Hong Kong
| | - W Xia
- University of Hong Kong, Hong Kong
| | - X L He
- People's Hospital of Hunan Province, China
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Aly AH, Aly AH, Lai EK, Yushkevich N, Stoffers RH, Gorman JH, Cheung AT, Gorman JH, Gorman RC, Yushkevich PA, Pouch AM. In Vivo Image-Based 4D Modeling of Competent and Regurgitant Mitral Valve Dynamics. Exp Mech 2021; 61:159-169. [PMID: 33776070 PMCID: PMC7988343 DOI: 10.1007/s11340-020-00656-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 08/05/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND In vivo characterization of mitral valve dynamics relies on image analysis algorithms that accurately reconstruct valve morphology and motion from clinical images. The goal of such algorithms is to provide patient-specific descriptions of both competent and regurgitant mitral valves, which can be used as input to biomechanical analyses and provide insights into the pathophysiology of diseases like ischemic mitral regurgitation (IMR). OBJECTIVE The goal is to generate accurate image-based representations of valve dynamics that visually and quantitatively capture normal and pathological valve function. METHODS We present a novel framework for 4D segmentation and geometric modeling of the mitral valve in real-time 3D echocardiography (rt-3DE), an imaging modality used for pre-operative surgical planning of mitral interventions. The framework integrates groupwise multi-atlas label fusion and template-based medial modeling with Kalman filtering to generate quantitatively descriptive and temporally consistent models of valve dynamics. RESULTS The algorithm is evaluated on rt-3DE data series from 28 patients: 14 with normal mitral valve morphology and 14 with severe IMR. In these 28 data series that total 613 individual 3DE images, each 3D mitral valve segmentation is validated against manual tracing, and temporal consistency between segmentations is demonstrated. CONCLUSIONS Automated 4D image analysis allows for reliable non-invasive modeling of the mitral valve over the cardiac cycle for comparison of annular and leaflet dynamics in pathological and normal mitral valves. Future studies can apply this algorithm to cardiovascular mechanics applications, including patient-specific strain estimation, fluid dynamics simulation, inverse finite element analysis, and risk stratification for surgical treatment.
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Affiliation(s)
- A H Aly
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - A H Aly
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - E K Lai
- Gorman Cardiovascular Research Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - N Yushkevich
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | | | - J H Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - A T Cheung
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University Medical Center, Stanford, CA, USA
| | - J H Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - R C Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - P A Yushkevich
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - A M Pouch
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
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Ho L, Li W, Cheung AT, Ho E, Lam K, Chiu SY, Chan G, Chung J. Relationships among hope, psychological well-being and health-related quality of life in childhood cancer survivors. J Health Psychol 2019; 26:1528-1537. [PMID: 31621412 DOI: 10.1177/1359105319882742] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
This cross-sectional study examined the level of hope among Hong Kong childhood cancer survivors and investigated the relationships among hope, depressive symptoms, self-esteem and health-related quality of life. We recruited 176 survivors aged 10-16 years who underwent medical follow-ups at the outpatient clinic. This study revealed that lower levels of hope were associated with an increase in depressive symptoms and reductions in self-esteem and health-related quality of life. Our results contribute to novel findings by demonstrating that hope may be a significant factor associated with health-related quality of life. This understanding could increase healthcare professionals' awareness about the psychological needs of childhood cancer survivors.
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Affiliation(s)
- Llk Ho
- The University of Hong Kong, Hong Kong
| | - Whc Li
- The University of Hong Kong, Hong Kong
| | | | - Eky Ho
- The University of Hong Kong, Hong Kong
| | - Kkw Lam
- The University of Hong Kong, Hong Kong
| | - S Y Chiu
- Hong Kong Children's Hospital, Hong Kong
| | - Gcf Chan
- Queen Mary Hospital, Hospital Authority, Hong Kong
| | - Jok Chung
- The University of Hong Kong, Hong Kong
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Chung J, Lam K, Ho KY, Cheung AT, Ho L, Gibson F, Li W. Relationships among resilience, self-esteem, and depressive symptoms in Chinese adolescents. J Health Psychol 2018; 25:2396-2405. [PMID: 30229681 DOI: 10.1177/1359105318800159] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
This study explored the relationships among resilience, self-esteem, and depressive symptoms in Hong Kong Chinese adolescents. We selected a stratified random sample of 1816 Form 1 students from all 18 districts of Hong Kong. This study revealed that about 21 percent adolescents are experiencing some depressive symptoms. Our results contribute novel findings to the literature showing that resilience is a strong indicator of adolescents at a higher risk of depression and increasing adolescents' resilience to psychological distress is crucial to enhance their mental well-being. It is crucial to develop interventions that can enhance resilience and promote positive mental well-being among adolescents.
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Affiliation(s)
- Jok Chung
- The University of Hong Kong, Hong Kong (SAR)
| | - Kkw Lam
- The University of Hong Kong, Hong Kong (SAR)
| | - K Y Ho
- The University of Hong Kong, Hong Kong (SAR)
| | - A T Cheung
- The University of Hong Kong, Hong Kong (SAR)
| | - Llk Ho
- The University of Hong Kong, Hong Kong (SAR)
| | - F Gibson
- University of Surrey, United Kingdom
| | - Whc Li
- The University of Hong Kong, Hong Kong (SAR)
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Lam NT, Covey SD, Lewis JT, Oosman S, Webber T, Hsu EC, Cheung AT, Kieffer TJ. Leptin resistance following over-expression of protein tyrosine phosphatase 1B in liver. J Mol Endocrinol 2006; 36:163-74. [PMID: 16461936 DOI: 10.1677/jme.1.01937] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Obesity is typically associated with resistance to leptin, yet the mechanism by which leptin signaling becomes impaired is poorly understood. Here we sought to determine if the development of obesity and leptin resistance correlates with increased expression of protein tyrosine phosphatase 1B (PTP1B) in peripheral tissues and whether over-expression of this phosphatase, specifically in liver, could alter the leptin-mediated effects on feeding and glucose metabolism. Obesity was induced in mice through a high-fat diet that resulted in hyperglycemia, hyperinsulinemia and hyperleptinemia. Resistance to leptin was confirmed as exogenous leptin administration reduced food intake in animals on low-fat, but not high-fat diets. Diet-induced resistance to leptin and insulin was associated with increased hepatic levels of PTP1B. Intriguingly, hepatic adenoviral over-expression of PTP1B in ob/ob mice attenuated the ability of exogenous leptin to reduce both plasma glucose levels and food intake. These findings suggest that leptin reduces both plasma glucose and food intake in part through actions on the liver, and hepatic leptin resistance resulting from over-expression of PTP1B may contribute to the development of both diabetes and obesity.
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Affiliation(s)
- N T Lam
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Driessen B, Zarucco L, Burns PM, Boston R, Gunther RA, Cheung AT. Pre-hospital low-volume resuscitation with hemoglobin-glutamer-200 (Hb-200) in a canine hemorrhagic shock model. Vet Anaesth Analg 2005. [DOI: 10.1111/j.1467-2995.2005.00232a_31.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Leptin suppresses insulin secretion by opening ATP-sensitive K(+) (K(ATP)) channels and hyperpolarizing beta-cells. We measured the intracellular concentration of ATP ([ATP](i)) in tumor-derived beta-cells, INS-1, and found that leptin reduced [ATP](i) by approximately 30%, suggesting that the opening of K(ATP) channels by leptin is mediated by decreased [ATP](i). A reduction in glucose availability for metabolism may explain the decreased [ATP](i), since leptin (30 min) reduced glucose transport into INS-1 cells by approximately 35%, compared to vehicle-treated cells. The twofold induction of GLUT2 phosphorylation by GLP-1, an insulin secretagogue, was abolished by leptin. Therefore, the acute effect of leptin could involve covalent modification of GLUT2. These findings suggest that leptin may inhibit insulin secretion by reducing [ATP](i) as a result of reduced glucose availability for the metabolic pathway. In addition, leptin reduced glucose transport by 35% in isolated rat hepatocytes that also express GLUT2, suggesting that glucose transport may also be altered by leptin in other glucose-responsive tissues such as the liver.
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Affiliation(s)
- N T Lam
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Wang J, Cheung AT, Kolls JK, Starks WW, Martinez-Hernandez A, Dietzen D, Bryer-Ash M. Effects of adenovirus-mediated liver-selective overexpression of protein tyrosine phosphatase-1b on insulin sensitivity in vivo. Diabetes Obes Metab 2001; 3:367-80. [PMID: 11703427 DOI: 10.1046/j.1463-1326.2001.00173.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIM Protein tyrosine phosphatase-1B (PTP-1B) is an intracellular PTP known to dephosphorylate and inactivate upstream tyrosine phosphoproteins in the insulin signalling cascade. We and others reported increased abundance of catalytically impaired PTP-1B in tissue lysates from obese human subjects with and without type 2 diabetes, while genetic knockout of PTP-1B improves insulin sensitivity and prevents nutritionally mediated insulin resistance and obesity. The aim of the present work was to further elucidate the role of PTP-1B in glucose metabolism in vivo. METHODS We used adenoviral constructs incorporating cDNAs for either wild-type (W/T) or a catalytically inactive C(215)S (C/S) mutant PTP-1B to achieve liver-selective PTP-1B overexpression in young Sprague-Dawley rats using tail vein injection, based on the high degree of hepatotropism of adenovirus 5 (Ad5). An Ad5-lacZ construct encoding beta-galactosidase was used as a control for viral effects alone. A hyperinsulinaemic euglycaemic clamp was used to study whole body glucose disposal and endogenous glucose production rates. RESULTS Control studies in HIRcB cells confirmed catalytic activity and inactivity of W/T and C/S respectively. Mean PTP-1B abundance was 2.24 +/- 0.02- and 2.33 +/- 0.04-fold of saline-treated control in liver lysates of W/T and C/S rats respectively. Liver selective overexpression was confirmed by analysis of tissue lysates from liver, fat and muscle tissues. Ad5 treatment did not result in a statistically or clinically significant liver injury, as determined by serum alanine aminotransferase and histological examination. Seven days post injection, no significant difference in rate of weight gain, fasting blood glucose or insulin levels were seen in any group. Similarly, under steady-state glucose clamp conditions, glucose disposal rate (R(d)), endogenous glucose production rate (EGP) and serum insulin levels were similar in all groups. CONCLUSION We conclude that moderate medium-term overabundance, to a degree resembling that seen in insulin-resistant states, of PTP-1B in liver tissue does not alter insulin action on glucose metabolism and that the major site of action of PTP-1B is presumably at insulin-responsive target tissue or tissues other than the liver.
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Affiliation(s)
- J Wang
- University of Tennessee, Memphis, TN, USA
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Cheung AT, Jahr JS, Driessen B, Duong PL, Chan MS, Lurie F, Golkaryeh MS, Kullar RK, Gunther RA. The effects of hemoglobin glutamer-200 (bovine) on the microcirculation in a canine hypovolemia model: a noninvasive computer-assisted intravital microscopy study. Anesth Analg 2001; 93:832-8. [PMID: 11574342 DOI: 10.1097/00000539-200110000-00007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
UNLABELLED We sought to correlate in vivo microvascular, systemic function, hemodynamic, and oxygenation changes in autologous shed blood (n = 4) and hemoglobin glutamer-200 (Hb-200) (n = 4) resuscitations in hypovolemic dogs. Hemorrhage (approximately 40% blood loss) reduced mean arterial pressure to approximately 50 mm Hg and caused significant (P < 0.01) decreases in hematocrit, total hemoglobin, mean pulmonary arterial pressure, cardiac output, and oxygen delivery and significant (P < 0.01) increases in heart rate, systemic vascular resistance, and lactic acidosis. Significant (P < 0.01) changes in conjunctival microvascular variables also occurred, including a 19% decrease in venular diameter and 79% increase in average blood flow velocity. Shed blood resuscitation returned microvascular, systemic function, hemodynamic, and oxygenation variables to prehemorrhagic baseline values. In contrast, Hb-200 failed to restore hematocrit, total hemoglobin, cardiac output, oxygen delivery index, and systemic venous resistance to baseline, but it restored other systemic functions and all hemodynamic and microvascular changes. In addition, Hb-200 resuscitation in hypovolemic dogs (approximately 40% blood loss) did not cause extreme hemodilution or fatal outcome. This study confirms that real-time (in vivo) microvascular studies, which were conducted only in small rodent models in the past, can be performed simultaneously with systemic function, hemodynamic, and oxygenation studies in a large animal model for relevant data correlation. IMPLICATIONS This is the first time that changes in the blood circulation have been studied, quantified, and correlated with systemic function, hemodynamic, and oxygenation changes in shock and during shock treatment in a large animal model. This study was performed by a new technology developed in-house to noninvasively and quantitatively study blood vessels in real time.
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Affiliation(s)
- A T Cheung
- Department of Medical Pathology, University of California Davis School of Medicine, Sacramento, California 95817, USA.
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Beauchamp K, Baker S, McDaniel C, Moser W, Zalman DC, Balinghoff J, Cheung AT, Stecker M. Reliability of nurses' neurological assessments in the cardiothoracic surgical intensive care unit. Am J Crit Care 2001. [DOI: 10.4037/ajcc2001.10.5.298] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
BACKGROUND: Alterations in mental status are common among patients in the cardiothoracic surgical intensive care unit. Changes in mental status can be caused by metabolic factors, medications, or brain injury. In this setting, reliable, serial neurological evaluations are critical for assessing the effectiveness of treatment and the need for additional studies. OBJECTIVES: To estimate the reliability of the Rancho Los Amigos Cognitive Scale and the newly developed Neurologic Intensive Care Evaluation as measures of cognitive function in the cardiothoracic surgical intensive care unit. METHODS: Nurses used 1 of the 2 scales as part of routine neurological assessments of patients in the cardiothoracic surgical intensive care unit. For each test, scores of different observers were correlated and a reliability estimate formed. RESULTS: Interrater reliability was high for both evaluations (Rancho scale, 0.91; Neurologic Intensive Care Evaluation, 0.94). Correlations between the scores of different pairs of observers were also high (mean rho values, 0.84 for the Rancho scale and 0.77 for the Neurologic Intensive Care Evaluation). CONCLUSIONS: Both scales are reliable indicators of the neurological state of patients in the cardiothoracic surgical intensive care unit. These scales measure different, although limited, aspects of cognitive function. Each test was simple to administer and did not take more time than the standard nursing neurological examination. Most of the variability in scoring was related to the different degrees of stimulation used by examiners when assessing patients, not to differences in the interpretation of patients' responses.
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Beauchamp K, Baker S, McDaniel C, Moser W, Zalman DC, Balinghoff J, Cheung AT, Stecker M. Reliability of nurses' neurological assessments in the cardiothoracic surgical intensive care unit. Am J Crit Care 2001; 10:298-305. [PMID: 11548562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
BACKGROUND Alterations in mental status are common among patients in the cardiothoracic surgical intensive care unit. Changes in mental status can be caused by metabolic factors, medications, or brain injury. In this setting, reliable, serial neurological evaluations are critical for assessing the effectiveness of treatment and the need for additional studies. OBJECTIVES To estimate the reliability of the Rancho Los Amigos Cognitive Scale and the newly developed Neurologic Intensive Care Evaluation as measures of cognitive function in the cardiothoracic surgical intensive care unit. METHODS Nurses used 1 of the 2 scales as part of routine neurological assessments of patients in the cardiothoracic surgical intensive care unit. For each test, scores of different observers were correlated and a reliability estimate formed. RESULTS Interrater reliability was high for both evaluations (Rancho scale, 0.91; Neurologic Intensive Care Evaluation, 0.94). Correlations between the scores of different pairs of observers were also high (mean rho values, 0.84 for the Rancho scale and 0.77 for the Neurologic Intensive Care Evaluation). CONCLUSIONS Both scales are reliable indicators of the neurological state of patients in the cardiothoracic surgical intensive care unit. These scales measure different, although limited, aspects of cognitive function. Each test was simple to administer and did not take more time than the standard nursing neurological examination. Most of the variability in scoring was related to the different degrees of stimulation used by examiners when assessing patients, not to differences in the interpretation of patients' responses.
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Affiliation(s)
- K Beauchamp
- Hospital of the University of Pennsylvania, Philadelphia, Pa., USA
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Abstract
OBJECTIVE To study and quantify microvascular abnormalities objectively in vivo in patients with type 2 diabetes mellitus (T2DM). METHODS The conjunctival microcirculation in 14 patients with T2DM and in age-matched healthy control subjects without diabetes was videotaped and objectively studied by using computer-assisted intravital microscopy (CAIM), a novel and quantitative real-time technology. RESULTS Patients with T2DM (N = 14) had significantly (P<0.01) wider conjunctival vessel diameters (71.9 +/- 5.2 mm) than did healthy nondiabetic control subjects (54.0 +/- 4.4 mm). In the study patients, microvascular distribution was significantly (P<0.01) abnormal (36.7 +/- 18.2 versus 45.3 +/- 9.6 cm per unit area, patients versus control subjects), and vessel distribution was uneven on the surface of the bulbar conjunctiva. The arteriole:venule (A:V) ratio in patients with T2DM was extremely variable and differed significantly (P<0.01) from that in the nondiabetic control subjects (A:V approximately 1:2). In addition, a unique sinusoidal (hypertensive) vascular pattern frequently existed in some of the large veins of all study patients with T2DM but in none of the nondiabetic control subjects. CONCLUSION We identified the presence of microvascular changes (abnormalities) in the conjunctival microcirculation of patients with T2DM. Although all these abnormalities did not appear in the same patient at the same time, the sum total of their presence in each patient correlated significantly with disease severity, as noted in the medical records. The severity of microvascular abnormalities, however, did not correlate with the duration of the disease since diagnosis. CAIM may be a useful objective and quantitative technique for assessing microangiopathy in patients with T2DM. The easy noninvasive accessibility of the conjunctival vessels and the ability to identify and locate the same vessels repeatedly for longitudinal evaluations further emphasize the usefulness of this real-time technology.
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Affiliation(s)
- A T Cheung
- Department of Medical Pathology, University of California, Davis Medical Center, 4645 Second Avenue, Sacramento, CA 95817, USA
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Cheung AT, Weiss SJ, Kent G, Pochettino A, Bavaria JE, Stecker MM. Intraoperative seizures in cardiac surgical patients undergoing deep hypothermic circulatory arrest monitored with EEG. Anesthesiology 2001; 94:1143-7. [PMID: 11465610 DOI: 10.1097/00000542-200106000-00033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- A T Cheung
- Department of Anesthesiology, University of Pennsylvania, Philadelphia 19104, USA.
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Cheung AT, Harmatz P, Wun T, Chen PC, Larkin EC, Adams RJ, Vichinsky EP. Correlation of abnormal intracranial vessel velocity, measured by transcranial Doppler ultrasonography, with abnormal conjunctival vessel velocity, measured by computer-assisted intravital microscopy, in sickle cell disease. Blood 2001; 97:3401-4. [PMID: 11369629 DOI: 10.1182/blood.v97.11.3401] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Stroke Prevention Trial has confirmed that utilization of transcranial Doppler ultrasonography (TCD), which examines blood flow in large intracranial vessels, can identify children with sickle cell disease (SCD) who are at high risk of developing a premature stroke. It is not known to what extent the vasculopathy in SCD involves small vessels and whether the abnormalities, if present, correlate with large-vessel vasculopathy. Eighteen children with SCD were examined with TCD to determine middle cerebral artery (MCA) velocity and computer-assisted intravital microscopy (CAIM) to determine bulbar conjunctival vessel velocity during the same visit for vasculopathy correlation. High MCA velocity (≥ 200 cm/sec) was found by TCD in 4 patients who also showed abnormal conjunctival velocity (< 0.2 mm/sec or intermittent trickle flow) by CAIM. Three patients had conditional (≥ 170 cm/sec and < 200 cm/sec) MCA velocity: 2 showed abnormal (trickle) and 1 showed normal conjunctival velocity (1.9 mm/sec). One patient with unmeasurable MCA velocity had abnormal (trickle) conjunctival velocity. Of the remaining 10 patients who had normal MCA velocity, 2 showed abnormal (0.05 mm/sec and 0.1 mm/sec) and 8 showed normal conjunctival velocities (1.1-2.4 mm/sec). The MCA velocities correlated significantly with bulbar conjunctival flow velocities (P ≤ .008, Fisher exact test). A correlation exists between MCA (large-vessel) and conjunctival (small-vessel) flow velocities. CAIM is a noninvasive quantitative technique that might contribute to the identification of SCD patients at high risk of stroke. Small-vessel vasculopathy might be an important pathological indicator and should be further explored in a large-scale study.
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Affiliation(s)
- A T Cheung
- Department of Medical Pathology, University of California Davis School of Medicine, 4645 Second Ave., Sacramento, CA 95817, USA.
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Egawa K, Maegawa H, Shimizu S, Morino K, Nishio Y, Bryer-Ash M, Cheung AT, Kolls JK, Kikkawa R, Kashiwagi A. Protein-tyrosine phosphatase-1B negatively regulates insulin signaling in l6 myocytes and Fao hepatoma cells. J Biol Chem 2001; 276:10207-11. [PMID: 11136729 DOI: 10.1074/jbc.m009489200] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin signaling is regulated by tyrosine phosphorylation of the signaling molecules, such as the insulin receptor and insulin receptor substrates (IRSs). Therefore, the balance between protein-tyrosine kinases and protein-tyrosine phosphatase activities is thought to be important in the modulation of insulin signaling in insulin-resistant states. We thus employed the adenovirus-mediated gene transfer technique, and we analyzed the effect of overexpression of a wild-type protein-tyrosine phosphatase-1B (PTP1B) on insulin signaling in both L6 myocytes and Fao cells. In both cells, PTP1B overexpression blocked insulin-stimulated tyrosine phosphorylation of the insulin receptor and IRS-1 by more than 70% and resulted in a significant inhibition of the association between IRS-1 and the p85 subunit of phosphatidylinositol 3-kinase and Akt phosphorylation as well as mitogen-activated protein kinase phosphorylation. Moreover, insulin-stimulated glycogen synthesis was also inhibited by PTP1B overexpression in both cells. These effects were specific for insulin signaling, because platelet-derived growth factor (PDGF)-stimulated PDGF receptor tyrosine phosphorylation and Akt phosphorylation were not inhibited by PTP1B overexpression. The present findings demonstrate that PTP1B negatively regulates insulin signaling in L6 and Fao cells, suggesting that PTP1B plays an important role in insulin resistance in muscle and liver.
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Affiliation(s)
- K Egawa
- Third Department of Medicine, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
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Stecker MM, Cheung AT, Pochettino A, Kent GP, Patterson T, Weiss SJ, Bavaria JE. Deep hypothermic circulatory arrest: II. Changes in electroencephalogram and evoked potentials during rewarming. Ann Thorac Surg 2001; 71:22-8. [PMID: 11216751 DOI: 10.1016/s0003-4975(00)02021-x] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Electrophysiologic studies during rewarming after deep hypothermic circulatory arrest probe the state of the brain during this critical period and may provide insight into the neurological effects of circulatory arrest and the neurologic outcome. METHODS Electroencephalogram (EEG) and evoked potentials were monitored during rewarming in 109 patients undergoing aortic surgery with hypothermic circulatory arrest. RESULTS The sequence of neurophysiologic events during rewarming did not mirror the events during cooling. The evoked potentials recovered first followed by EEG burst-suppression and then continuous EEG. The time to recovery of the evoked potentials N20-P22 complex was significantly correlated with the time of circulatory arrest even in patients without postoperative neurologic deficits (r = 0.37, (p = 0.002). The nasopharyngeal temperatures at which continuous EEG activity and the N20-P22 complex returned were strongly correlated (r = 0.44, p = 0.0002; r = 0.41, p = 0.00003) with postoperative neurologic impairment. Specifically, the relative risk for postoperative neurologic impairment increased by a factor of 1.56 (95% CI 1.1 to 2.2) for every degree increase in temperature at which the EEG first became continuous. CONCLUSIONS No trend toward shortened recovery times or improved neurologic outcome was noted with lower temperatures at circulatory arrest, indicating that the process of cooling to electrocerebral silence produced a relatively uniform degree of cerebral protection, independent of the actual nasopharyngeal temperature.
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Affiliation(s)
- M M Stecker
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, USA.
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Stecker MM, Cheung AT, Pochettino A, Kent GP, Patterson T, Weiss SJ, Bavaria JE. Deep hypothermic circulatory arrest: I. Effects of cooling on electroencephalogram and evoked potentials. Ann Thorac Surg 2001; 71:14-21. [PMID: 11216734 DOI: 10.1016/s0003-4975(00)01592-7] [Citation(s) in RCA: 198] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Deep hypothermia is an important cerebral protectant and is critical in procedures requiring circulatory arrest. The purpose of this study was to determine the factors that influence the neurophysiologic changes during cooling before circulatory arrest, in particular the occurrence of electrocerebral silence. METHODS In 109 patients undergoing hypothermic circulatory arrest with neurophysiologic monitoring, five electrophysiologic events were selected for detailed study. RESULTS The mean nasopharyngeal temperature when periodic complexes appeared in the electroencephalogram after cooling was 29.6 degrees C +/- 3 degrees C, electroencephalogram burst-suppression appeared at 24.4 degrees C +/- 4 degrees C, and electrocerebral silence appeared at 17.8 degrees C +/- 4 degrees C. The N20-P22 complex of the somatosensory evoked response disappeared at 21.4 degrees C +/- 4 degrees C, and the somatosensory evoked response N13 wave disappeared at 17.3 degrees C +/- 4 degrees C. The temperatures of these various events were not significantly affected by any patient-specific or surgical variables, although the time to cool to electrocerebral silence was prolonged by high hemoglobin concentrations, low arterial partial pressure of carbon dioxide, and by slow cooling rates. Only 60% of patients demonstrated electrocerebral silence by either a nasopharyngeal temperature of 18 degrees C or a cooling time of 30 minutes. CONCLUSIONS With the high degree of interpatient variability in these neurophysiologic measures, the only absolute predictors of electrocerebral silence were nasopharyngeal temperature below 12.5 degrees C and cooling longer than 50 minutes.
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Affiliation(s)
- M M Stecker
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, USA.
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18
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Cheung AT, Dayanandan B, Lewis JT, Korbutt GS, Rajotte RV, Bryer-Ash M, Boylan MO, Wolfe MM, Kieffer TJ. Glucose-dependent insulin release from genetically engineered K cells. Science 2000; 290:1959-62. [PMID: 11110661 DOI: 10.1126/science.290.5498.1959] [Citation(s) in RCA: 201] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Genetic engineering of non-beta cells to release insulin upon feeding could be a therapeutic modality for patients with diabetes. A tumor-derived K-cell line was induced to produce human insulin by providing the cells with the human insulin gene linked to the 5'-regulatory region of the gene encoding glucose-dependent insulinotropic polypeptide (GIP). Mice expressing this transgene produced human insulin specifically in gut K cells. This insulin protected the mice from developing diabetes and maintained glucose tolerance after destruction of the native insulin-producing beta cells.
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Affiliation(s)
- A T Cheung
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2S2, Canada
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19
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Guvakov DV, Cheung AT, Weiss SJ, Kalinin NB, Fedorenko NO, Shunkin AV, Lomivorotov VN, Karaskov AM. Effectiveness of forced air warming after pediatric cardiac surgery employing hypothermic circulatory arrest without cardiopulmonary bypass. J Clin Anesth 2000; 12:519-24. [PMID: 11137412 DOI: 10.1016/s0952-8180(00)00210-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
STUDY OBJECTIVE To evaluate the effectiveness of forced-air warming compared to radiant warming in pediatric cardiac surgical patients recovering from moderate hypothermia after perfusionless deep hypothermic circulatory arrest. DESIGN Prospective unblinded study. SETIING: Teaching hospitals. PATIENTS 24 pediatric cardiac surgical patients. INTERVENTION Noncyanotic patients undergoing repair of atrial or ventricular septal defects were cooled by topical application of ice and rewarmed initially in the operating room by warm saline lavage of the pleural cavities. On arrival at the intensive care unit (ICU), patients were warmed by forced air (n = 13) or radiant heat (n = 11). The time, heart rate, and blood pressure at each 0.5 degrees C increase in rectal temperature were measured until normothermia (36.5 degrees C) to determine the instantaneous rewarming rate. MEASUREMENTS AND MAIN RESULTS Baseline characteristics were not different in the two groups. The mean (+/- SD) age was 5.6 +/- 3.4 years, weight was 20 +/- 8 kg, esophageal temperature for circulatory arrest was 25.7 +/- 1.3 degrees C, and duration of circulatory arrest was 25 +/- 11 minutes. The mean core temperature on arrival at the ICU was 29.9 +/- 1.3 degrees C and ranged from 26.1 to 31.5 degrees C. The mean rewarming rate for each 0.5 degrees C was greater (p < 0.05) for forced-air (2.43 +/- 1.14 degrees C/hr) than radiant heat (2.16 +/- 1.02 degrees C/hr). At core temperatures <33 degrees C, the rewarming rate for forced-air was 2.04 +/- 0.84 degrees C/hr and radiant heat was 1.68 +/- 0.84 degrees C/hr (p < 0.05). At core temperatures > or = 33 degrees C, the rewarming rate for forced air was 2.76 +/- 1.20 degrees C/hr and radiant heat was 2.46 +/- 1.08 degrees C/min (p = 0.07). Significant determinants of the rewarming rate in a multivariate regression model were age (p < 0.001), temperature (p < 0.05), time after arrival to the intensive care unit (p < 0.05), pulse pressure (p < 0. 05) and warming device (p < 0.001). The duration of ventilatory support and ICU length of stay was not different in the two groups. CONCLUSIONS Both forced-air and radiant heat were effective for rewarming moderately hypothermic pediatric patients. When core temperature was less than 33 degrees C, the instantaneous rewarming rate by forced air was 21% faster than by radiant heat.
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Affiliation(s)
- D V Guvakov
- Department of Anesthesiology, Novosibirsk Institute of Circulatory Pathology, Russia.
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20
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Abstract
The neurologic evaluation of patients in the immediate postoperative period and postanesthetic state is unique and challenging. Neurologic assessment is complicated by the lingering residual effects of anesthetics as well as by the effects of narcotic analgesics, anxiolytics, and muscle relaxants, especially in ventilated patients. In this review we examine the suspected causes, clinical manifestations, diagnostic options, and intervention schemes for the common neurologic syndromes seen after cardiac operations.
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Affiliation(s)
- T F Floyd
- Department of Anesthesia, University of Pennsylvania, Philadelphia, PA 19104-4283, USA
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21
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Abstract
UNLABELLED Our goal was to determine and predict the effects of temperature, shear rate, hematocrit, and different volume expanders on blood viscosity in conditions mimicking deep hypothermia for cardiac operations. Blood was obtained from six healthy adults. Dilutions were prepared to hematocrits of 35%, 30%, 22.5%, and 15% using plasma, 0.9% NaCl, 5% human albumin, and 6% hydroxyethyl starch. Viscosity was measured over a range of shear rates (4.5-450 s(-1)) and temperature (0 degrees -37 degrees C). A parametric expression for predicting blood viscosity based on the study variables was developed, and its agreement with measured values tested. Viscosity was higher at low shear rates and low temperatures, especially at temperatures less than 15 degrees C (P: < 0.016 for all conditions in comparison with 37 degrees C). Decreasing hematocrit, especially to less than 22.5%, decreased viscosity. Hemodilution with albumin or 0.9% NaCl decreased blood viscosity more than hemodilution with plasma or 6% hydroxyethyl starch (P: < 0.01 for all cases). The derived mathematical model for viscosity as a function of temperature, hematocrit, shear rate, and diluent predicted viscosity values that correlated well with the measured values in experimental samples (r(2) > 0.92, P: < 0.001). IMPLICATIONS A theoretical model for blood viscosity predicted independent effects of temperature, shear rate, and hemodilution on viscosity over a wide range of physiologic conditions, including thermal extremes of deep hypothermia in an experimental setting. Moderate hemodilution to a hematocrit of 22% decreased blood viscosity by 30%-50% at a blood temperature of 15 degrees C, suggesting the potential to improve microcirculatory perfusion during deep hypothermia.
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Affiliation(s)
- D M Eckmann
- Departments of Anesthesia and Neurology, and Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia 19096, USA.
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22
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Cheung AT, Wang J, Ree D, Kolls JK, Bryer-Ash M. Tumor necrosis factor-alpha induces hepatic insulin resistance in obese Zucker (fa/fa) rats via interaction of leukocyte antigen-related tyrosine phosphatase with focal adhesion kinase. Diabetes 2000; 49:810-9. [PMID: 10905491 DOI: 10.2337/diabetes.49.5.810] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The molecular mechanism whereby tumor necrosis factor-alpha (TNF-alpha) induces insulin resistance in obesity is not well understood. Previously, we have shown that inhibition of TNF-alpha improved hepatic insulin sensitivity in obese Zucker rats without altering the tyrosine phosphorylation of liver insulin receptors (IRs), which indicates that the TNF-alpha and insulin-signaling cascades interact distally to the IR. To assess the effects of TNF-alpha on signaling molecules downstream from the IR, we analyzed the tyrosine phosphorylation patterns of liver homogenate proteins from TNF-alpha-neutralized fa/fa rats and showed that focal adhesion kinase (FAK) was consistently hyperphosphorylated (4.5-fold). Moreover, intravenous insulin increased hepatic FAK phosphorylation in a time-dependent manner in Sprague-Dawley rats, which suggests that TNF-alpha may induce hepatic insulin resistance by preventing FAK phosphorylation in response to insulin treatment. To explore the cellular mechanism whereby TNF-alpha regulates phosphorylation of FAK in the liver, we measured c-Src kinase activity and the abundance of 3 major protein tyrosine phosphatases (PTPs) (PTP-1B, leukocyte antigen-related tyrosine phosphatase [LAR], and src homology 2 domain-containing protein-tyrosine phosphatase [SHPTP-2]) in liver homogenates from obese Zucker rats after TNF-alpha blockade. Hepatic c-Src kinase activity was unaltered, but LAR protein was reduced by 75%. In addition, TNF-alpha blockade reduced hepatic PTP activity toward tyrosine phosphorylated FAK by 70%, and this was accounted for by immunodepletion of LAR. Incubation of HepG2 cells with TNF-alpha increased LAR protein levels in a dose-dependent manner. Additionally, pretreatment with TNF-alpha abolished insulin-stimulated tyrosine phosphorylation of FAK in HepG2 cells but had no effect on IR tyrosine phosphorylation or expression. These data suggest that TNF-alpha promotes LAR expression and thus prevents insulin-mediated tyrosine phosphorylation of FAK. This probably represents the interface between TNF-alpha and insulin signaling in the liver.
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Affiliation(s)
- A T Cheung
- Department of Physiology, Tulane University School of Medicine, New Orleans, Louisiana, USA
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23
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Cheung AT, Guvakov DV, Weiss SJ, Savino JS, Salgo IS, Meng QC. Nicardipine intravenous bolus dosing for acutely decreasing arterial blood pressure during general anesthesia for cardiac operations: pharmacokinetics, pharmacodynamics, and associated effects on left ventricular function. Anesth Analg 1999; 89:1116-23. [PMID: 10553821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
UNLABELLED The objective of this study was to evaluate the efficacy of nicardipine, a dihydropyridine calcium channel antagonist, administered as an IV bolus dose to acutely decrease arterial pressure in anesthetized cardiac surgical patients. We performed a double-blind, randomized, self-controlled, dose-ranging study in 40 adult cardiac surgical patients to determine the pharmacokinetics and pharmacodynamics of nicardipine 0.25 mg, 0.50 mg, 1.00 mg, and 2.00 mg administered as an IV bolus. Transesophageal echocardiography was used to assess left ventricular preload, afterload, and global systolic function. Plasma nicardipine concentration was measured using high-performance liquid chromatography. Nicardipine selectively decreased arterial pressure in a dose-dependent manner with a maximum response within 100 s and recovery to half the maximum response within 3-7 min without associated changes in heart rate. The decreases in arterial pressure were associated with only small decreases in left ventricular end-systolic wall stress and small increases in global left ventricular systolic function without changes in left ventricular end-diastolic cavity area or cardiac output. The time course for nicardipine bolus was consistent with a two-compartment pharmacokinetic model with rapid redistribution from a small central compartment. IMPLICATIONS Nicardipine was effective for selectively decreasing arterial blood pressure acutely, but had no effects on ventricular preload or cardiac output. The absence of dose-dependent changes in cardiac output, left ventricular systolic performance, and left ventricular afterload despite significant decreases in arterial pressure suggested that nicardipine had a small negative inotropic action.
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Affiliation(s)
- A T Cheung
- Department of Anesthesia, University of Pennsylvania, Philadelphia 19104-4283, USA.
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24
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Cheung AT, Perez RV, Chen PC. Improvements in diabetic microangiopathy after successful simultaneous pancreas-kidney transplantation: a computer-assisted intravital microscopy study on the conjunctival microcirculation. Transplantation 1999; 68:927-32. [PMID: 10532529 DOI: 10.1097/00007890-199910150-00005] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A computer-assisted intravital microscopy technology has been developed to noninvasively and objectively study diabetic microangiopathy in the conjunctival microcirculation of type-1 diabetics. Quantitative characterization of the conjunctival microcirculation was performed on 12 patients pre- and 18 months postsimultaneous pancreas-kidney transplantation (SPK). Healthy nondiabetic volunteers (n=12), solitary kidney (K) transplanted type-1 diabetics (n=5), and nontransplanted type-1 diabetics (n=12) served as controls. Pre-SPK diabetics showed abnormal-sized venules (diameter=66+/-7 microm) and reduced presence of arterioles (arteriole length/area=18+/-6 microm(-1)) compared with nondiabetic controls (53+/-4 microm; 31+/-8 microm(-1); P<0.05). The computed vascular perfusion capacity of the conjunctival microvasculature was diminished in the same patients (pre-SPK diabetics=49+/-9%; nondiabetic healthy controls=71+/-6%; P<0.05). Significant improvement in microangiopathy was observed in all post-SPK diabetics (diameter=58+/-6 microm; arteriole length/area=26+/-9 microm(-1); vascular perfusion=63+/-8%; P<0.05) 18 months post-SPK. Blood flow velocities in the conjunctival microcirculation in the same post-SPK patients showed noticeable but not significant improvements (nondiabetic controls=2.94+/-0.57 mm/sec; pre-SPK=1.23+/-0.49 mm/sec; post-SPK=1.65+/-0.42 mm/sec). The solitary kidney transplant controls (post-K) showed no significant improvements in diabetic microangiopathy, confirming the unique role of the pancreas in SPK. In general, significant improvements (P<0.05) in diabetic microangiopathy were observed in all 12 diabetics 18 months post-SPK but not in the controls.
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Affiliation(s)
- A T Cheung
- Department of Medical Pathology, UC Davis Medical Center, Sacramento, California 95817, USA
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25
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Shanewise JS, Cheung AT, Aronson S, Stewart WJ, Weiss RL, Mark JB, Savage RM, Sears-Rogan P, Mathew JP, Quiñones MA, Cahalan MK, Savino JS. ASE/SCA guidelines for performing a comprehensive intraoperative multiplane transesophageal echocardiography examination: recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists Task Force for Certification in Perioperative Transesophageal Echocardiography. Anesth Analg 1999; 89:870-84. [PMID: 10512257 DOI: 10.1097/00000539-199910000-00010] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- J S Shanewise
- Division of Cardiac Anesthesia and Critical Care, Emory University School of Medicine, Atlanta, Georgia, USA
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26
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Shanewise JS, Cheung AT, Aronson S, Stewart WJ, Weiss RL, Mark JB, Savage RM, Sears-Rogan P, Mathew JP, Quiñones MA, Cahalan MK, Savino JS. ASE/SCA guidelines for performing a comprehensive intraoperative multiplane transesophageal echocardiography examination: recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists Task Force for Certification in Perioperative Transesophageal Echocardiography. J Am Soc Echocardiogr 1999; 12:884-900. [PMID: 10511663 DOI: 10.1016/s0894-7317(99)70199-9] [Citation(s) in RCA: 233] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- J S Shanewise
- American Society of Echocardiography, Raleigh, NC 27607, USA
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Abstract
The accepted importance of circulatory impairment to sickle cell anemia remains to be verified by in vivo experimentation. Intravital microscopy studies of blood flow in patients are limited to circulations that can be viewed noninvasively and are restricted from deliberate perturbations of the circulation. Further knowledge of sickle blood flow abnormalities has awaited an animal model of human sickle cell disease. We compared blood flow in the mucosal-intestinal microvessels of normal mice with that in transgenic knockout sickle cell mice that have erythrocytes containing only human hemoglobin S and that exhibit a degree of hemolytic anemia and pathological complications similar to the human disease. In sickle cell mice, in addition to seeing blood flow abnormalities such as sludging in all microvessels, we detected decreased blood flow velocity in venules of all diameters. Flow responses to hyperoxia in both normal and sickle cell mice were dramatic, but opposite: Hyperoxia promptly slowed or halted flow in normal mice but markedly enhanced flow in sickle cell mice. Intravital microscopic studies of this murine model provide important insights into sickle cell blood flow abnormalities and suggest that this model can be used to evaluate the causes of abnormal flow and new approaches to therapy of sickle cell disease.
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Affiliation(s)
- S H Embury
- Division of Hematology and Department of Medicine, San Francisco General Hospital and the University of California-San Francisco, San Francisco, California 94110, USA.
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Lau DH, Xue L, Young LJ, Burke PA, Cheung AT. Paclitaxel (Taxol): an inhibitor of angiogenesis in a highly vascularized transgenic breast cancer. Cancer Biother Radiopharm 1999; 14:31-6. [PMID: 10850285 DOI: 10.1089/cbr.1999.14.31] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Paclitaxel (Taxol), a promoter of microtubule polymerization and a radiosensitizing agent, is one of the more active anticancer drugs in the current treatment of solid tumors. In this study, we show that paclitaxel possesses an antiangiogenic property associated with a down-regulation of vascular endothelial growth factor (VEGF) in a highly-vascularized transgenic murine breast cancer (Met-1). Paclitaxel, at non-cytotoxic doses of 0, 3 and 6 mg/kg/day, was administered intraperitoneally for 5 days to nude mice bearing the Met-1 breast tumor. Extent of intratumoral angiogenesis, as indicated by microvessel tortuosity and microvessel density, was significantly reduced by paclitaxel in a dose-dependent manner. Paclitaxel also suppressed expression of VEGF in the Met-1 cells transplanted in nude mice or maintained in cell culture. These results indicate that antiangiogenesis associated with a down-regulation of VEGF is an additional mode of action of paclitaxel.
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Affiliation(s)
- D H Lau
- Department of Internal Medicine, School of Medicine, University of California, Davis, Sacramento 95817, USA.
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29
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Abstract
UNLABELLED Retrograde cerebral perfusion (RCP) potentially delivers metabolic substrate to the brain during surgery using hypothermic circulatory arrest (HCA). Serial measurements of O2 extraction ratio (OER), PCO2, and pH from the RCP inflow and outflow were used to determine the time course for O2 delivery in 28 adults undergoing aortic reconstruction using HCA with RCP. HCA was instituted after systemic cooling on cardiopulmonary bypass for 3 min after the electroencephalogram became isoelectric. RCP with oxygenated blood at 10 degrees C was administered at an internal jugular venous pressure of 20-25 mm Hg. Serial analyses of blood oxygen, carbon dioxide, pH, and hemoglobin concentration were made in samples from the RCP inflow (superior vena cava) and outflow (innominate and left carotid arteries) at different times after institution of RCP. Nineteen patients had no strokes, five patients had preoperative strokes, and four patients had intraoperative strokes. In the group of patients without strokes, HCA with RCP was initiated at a mean nasopharyngeal temperature of 14.3 degrees C with mean RCP flow rate of 220 mL/min, which lasted 19-70 min. OER increased over time to a maximal detected value of 0.66 and increased to 0.5 of its maximal detected value 15 min after initiation of HCA. The RCP inflow-outflow gradient for PCO2 (slope 0.73 mm Hg/min; P < 0.001) and pH (slope 0.007 U/min; P < 0.001) changed linearly over time after initiation of HCA. In the group of patients with preoperative or intraoperative strokes, the OER and the RCP inflow-outflow gradient for PCO2 changed significantly more slowly over time after HCA compared with the group of patients without strokes. During RCP, continued CO2 production and increased O2 extraction over time across the cerebral vascular bed suggest the presence of viable, but possibly ischemic tissue. Reduced cerebral metabolism in infarcted brain regions may explain the decreased rate of O2 extraction during RCP in patients with strokes. IMPLICATIONS Examining the time course of oxygen extraction, carbon dioxide production, and pH changes from the retrograde cerebral perfusate provided a means to assess metabolic activity during hypothermic circulatory arrest.
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Affiliation(s)
- A T Cheung
- Department of Anesthesiology, University of Pennsylvania, Philadelphia 19104-4283, USA
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Cheung AT, Ree D, Kolls JK, Fuselier J, Coy DH, Bryer-Ash M. An in vivo model for elucidation of the mechanism of tumor necrosis factor-alpha (TNF-alpha)-induced insulin resistance: evidence for differential regulation of insulin signaling by TNF-alpha. Endocrinology 1998; 139:4928-35. [PMID: 9832430 DOI: 10.1210/endo.139.12.6336] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) has been shown to induce insulin resistance in cultured cells as well as in animal models. The aim of this study was to map the in vivo mechanism whereby TNF-alpha contributes to the pathogenesis of impaired insulin signaling, using obese and lean Zucker rats in which TNF-alpha activity was inhibited through adenovirus-mediated gene transfer. We employed a replication-incompetent adenovirus-5 (Ad5) vector to endogenously express a TNF inhibitor (TNFi) gene, which encodes a chimeric protein consisting of the extracellular domain of the human 55-kDa TNF receptor joined to a mouse IgG heavy chain. Control animals consisted of rats infected with the same titer of adenovirus carrying the lac-z complementary DNA, encoding for beta-galactosidase. There was a significant reduction in plasma insulin and free fatty acid levels in TNFi obese rats 2 days following Ad5 administration. The peripheral insulin sensitivity index was 50% greater, whereas hepatic glucose output was completely suppressed during hyperinsulinemic glucose clamps in TNFi obese animals, with no differences observed between the two lean groups. The improvement in peripheral and hepatic sensitivity to insulin seen in the obese animals was independent of insulin receptor (IR) number and insulin binding affinity for IR. However, TNF-alpha neutralization led to a 2.5-fold increase in tyrosine phosphorylation of IR in skeletal muscle, whereas this was unchanged in liver. There was also a 4-fold increase in particulate protein tyrosine phosphatase activity of skeletal muscle in TNFi obese animals vs. beta-galactosidase controls, whereas protein tyrosine phosphatase activity in liver was unchanged. These results suggest that TNF-alpha is a mediator of insulin resistance in obesity and may modulate IR signaling in skeletal muscle and liver through different pathways. TNF-alpha may affect insulin action in the liver either at sites distal to the IR or indirectly, possibly because of increased provision of gluconeogenic substrates or altered counterregulation. In addition, the Ad5-mediated gene delivery system employed here provides an in vivo model that is efficient and economical for exploring mechanisms involved in TNF-alpha-induced insulin resistance in various genetic models of obesity-linked diabetes.
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Affiliation(s)
- A T Cheung
- Department of Physiology, Tulane University, New Orleans, Louisiana, USA
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Abstract
PURPOSE In a rabbit model, transposition of a muscle pedicle flap to an ischemic hind limb has been shown to result in the development of new blood vessels that connect the arterial circulation of the flap to the circulation of the limb. The hypothesis that exogenous recombinant basic fibroblast growth factor (bFGF) would enhance the development of this new blood supply was examined and the regulation of bFGF in this process was investigated. METHODS The right common iliac artery was ligated in 12 male New Zealand white rabbits. An abdominal wall muscle flap based on the left inferior epigastric artery was transposed to the right thigh. bFGF in phosphate-buffered saline (PBS) at 3 ng/h (n = 6), or PBS alone (n = 6), was infused for 7 days via mini-osmotic pumps with an infusion catheter positioned at the flap-muscle interface. The flap-muscle interface was immunostained with anti-alpha-actin antibody to determine blood vessel density (number of vessels/mm) and with anti-bFGF antibody to evaluate bFGF distribution. RNA was isolated from these sections, and polymerase chain reaction (PCR) was used to examine endogenous bFGF messenger RNA (mRNA) expression. RESULTS Blood vessel density was significantly increased in animals receiving exogenous bFGF (22. 0 +/- 10.6 vessels/mm vs. 10.7 +/- 8.8 vessels/mm, P =.009). In the controls, neovessels were arranged in clusters with endogenous bFGF concentrated around these clusters. In bFGF-treated animals, vessels were diffusely scattered throughout the flap-limb interface, corresponding to the distribution pattern of infused bFGF. There was no difference in bFGF mRNA expression between the control and the bFGF-treated groups. CONCLUSION Exogenous bFGF infusion significantly augmented new blood vessel development at the flap-limb interface. Endogenous bFGF was up-regulated around the newly developed microvessels in control animals, and vessel growth correlated with the diffuse distribution of exogenous bFGF, implicating bFGF as an important factor in angiogenesis. Exogenous bFGF did not affect bFGF mRNA expression, suggesting that the regulation of bFGF is not under autocrine control.
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Affiliation(s)
- R L Bush
- Department of Surgery, and the Department of Pathology, University of California Medical Center, Davis, and the Department of Molecular Biology, Shriners Childrens Hospital, Tampa, FL, USA
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Meng QC, Cheung AT, Guvakov D, Weiss SJ, Savino JS, Salgo IS, Marshall BE. Extraction and quantification of nicardipine in human plasma. J Chromatogr B Biomed Sci Appl 1998; 718:121-7. [PMID: 9832368 DOI: 10.1016/s0378-4347(98)00352-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A novel simple method of extraction, separation, identification and quantification of nicardipine in human plasma samples was completely studied. The human plasma samples were initially purified by solid-phase extraction (SPE) using a C18 cartridge. The extracted samples were separated and nicardipine present in the samples was quantified by high-performance liquid chromatography (HPLC) on a reversed-phase C18 column employing a mobile phase consisting of 60% (v/v) acetonitrile in 0.02 M NaH2PO4 with pH of 6.3 and a variable wavelength UV detector set at 254 nm. The recovery of nicardipine from plasma samples using selective SPE was 91+/-6.0% and had less interfering compounds in the HPLC analysis compared to the use of liquid-liquid (L/L) extraction. In the HPLC analysis, examining the effect of pH values of the mobile phase on the capacity factor (k') of nicardipine revealed a method for selecting a critical k' value of nicardipine to eliminate interfering peaks near the peak specific to the analyte. This method for quantification of nicardipine in human plasma samples was suitable for studying the pharmacokinetic profile of nicardipine administered as an intravenous bolus to cardiac surgical patients.
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Affiliation(s)
- Q C Meng
- Center for Research in Anesthesia, Department of Anesthesia, University of Pennsylvania Health System, Philadelphia 19104, USA
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Pecha RE, Prindiville T, Kotfila R, Ruebner B, Cheung AT, Trudeau W. Gastrointestinal hemorrhage consequent to foreign body reaction to silk sutures: case series and review. Gastrointest Endosc 1998; 48:299-301. [PMID: 9744610 DOI: 10.1016/s0016-5107(98)70196-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
- R E Pecha
- Department of Pathology, University of California, Davis Medical Center, Sacramento 95817, USA
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Abstract
OBJECTIVE The results of neurophysiologic monitoring using somatosensory evoked potentials (SSEPs) and electroencephalography (EEG) were analyzed to determine if retrograde cerebral perfusion (RCP) supported central nervous system electrical function during surgery that required temporary interruption of antegrade cerebral perfusion (IACP). DESIGN A prospective, observational study. SETTING A university hospital. PARTICIPANTS Fifteen adult patients who underwent aortic reconstruction using RCP and three patients who underwent thoracic aortic operations using hypothermic circulatory arrest without RCP. INTERVENTIONS SSEPs and EEG were monitored continuously throughout the operation. Regression analysis was performed to determine the factors that affected the rate of decrease in SSEP amplitudes during IACP and the time required for SSEP and EEG activity to recover after antegrade cerebral perfusion (ACP) was restored. MEASUREMENTS AND MAIN RESULTS The amplitude of SSEPs that were elicited decreased over time after IACP. The mean +/- standard deviation (SD) time required for the brachial plexus (Erb's point), cervicomedullary junction (N13), and brainstem (N18) SSEPs to decrease to 0.5 of their original amplitude after IACP were 30 +/- 2, 19 +/- 2, and 16 +/- 2 minutes, respectively. The rate of decrease in the N18 SSEP amplitude after IACP correlated positively to the fraction of no-flow time (p = 0.01). CONCLUSION RCP attenuated the rate of decay in SSEP amplitudes during IACP. This suggested that RCP had a measurable physiologic effect on central nervous system function and may increase the time that ACP can be safely interrupted.
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Affiliation(s)
- A T Cheung
- Department of Anesthesiology, University of Pennsylvania, Philadelphia 19104-4283, USA
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Ahlfors CE, Alley PA, Prendergast JJ, Parks S, Cheung AT. Effect of Implanted Insulin Pumpson Fluorescein Transcapillary Escape Timein Type 1 Diabetes Mellitus. Endocr Pract 1998; 4:73-5. [PMID: 15251748 DOI: 10.4158/ep.4.2.73] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To determine whether significant increases in fluorescein transcapillary escape time (FTET) would occur after treatment of patients with type 1 diabetes with insulin delivered intraperitoneally by a surgically implanted pump. METHODS Nine patients with type 1 diabetes who were otherwise healthy and had received surgically implanted insulin pumps on a study protocol were recruited to have three measurements of FTET and glycosylated hemoglobin during an 18-month period. Serum fluorescein-albumin binding was measured at the time of the final test. Control FTETs were measured in 46 patients with type 1 diabetes who did not have insulin pumps and in 15 adults without diabetes. RESULTS In the implanted insulin pump group, 50% of the FTETs were below normal, but no significant longitudinal change in FTETs was noted in eight of the nine study patients. The mean FTETs in the implanted insulin pump group were significantly higher than those of the control patients with diabetes but without insulin pumps (mean, 88 versus 62 seconds; P<0.05) but significantly lower than those of the control subjects without diabetes (88 versus 163 seconds; P<0.001). Four of the nine patients with implanted insulin pumps had normal FTETs on all three studies. This subgroup had used insulin pumps (external + implanted) for significantly longer periods (6.2 versus 2.6 years; P<0.05) than the other five patients. These differences within the implanted pump group did not correlate with differences in glycosylated hemoglobin values or fluorescein-albumin binding; however, the glycosylated hemoglobin levels before insulin pump implantation were significantly lower than those of the other five patients. Three patients with onset of type 1 diabetes before age 10 years had the lowest FTETs. CONCLUSION Implanted insulin pumps did not alter FTETs between 6 months and 32 months after pump implantation. Total time on insulin pumps (external and implanted) is associated with normal FTET, and onset of diabetes before age 10 years is associated with abnormal FTET.
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Affiliation(s)
- C E Ahlfors
- Department of Pediatrics, California Pacific Medical Center, San Francisco, California 94118, USA
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Cheung AT, Levy WJ, Weiss SJ, Barclay DK, Stecker MM. Relationships between cerebral blood flow velocities and arterial pressures during intra-aortic counterpulsation. J Cardiothorac Vasc Anesth 1998; 12:51-7. [PMID: 9509357 DOI: 10.1016/s1053-0770(98)90055-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To determine the effects of intra-aortic counterpulsation (IABP) on cerebral blood flow velocity. DESIGN Prospective self-controlled study. SETTING University hospital surgical intensive care unit. PARTICIPANTS Nineteen cardiac surgical patients requiring perioperative IABP assistance. INTERVENTIONS Simultaneous recording of transcranial Doppler middle cerebral artery blood flow velocity and arterial pressure in response to changes in the magnitude of augmentation and trigger ratio. MEASUREMENTS AND MAIN RESULTS Instantaneous cerebral blood flow velocities correlated with arterial pressures during IABP (r = 0.650) at different magnitudes of augmentation and trigger ratios. The increase in arterial pressure during balloon inflation was associated with an increase in cerebral blood flow velocity, and the decrease in arterial pressure in response to balloon deflation was associated with a decrease in cerebral blood flow velocity that was dependent on the magnitude of augmentation. Different magnitudes of augmentation or trigger ratios had no effect on peak systolic cerebral blood flow velocity, mean cerebral blood flow velocity, mean arterial pressure, or the mean velocity-to-pressure ratio. Instantaneous cerebral blood flow velocity to arterial pressure ratios were lowest in response to balloon deflation at the time of pre-ejection. CONCLUSIONS IABP modified the phasic profile of cerebral blood flow to reflect the arterial pressure waveform without affecting mean cerebral blood flow velocity. Peak systolic cerebral blood flow velocity was maintained in augmented beats despite the decreased systolic arterial pressure associated with afterload reduction. The acute decrease in cerebral blood flow velocity at pre-ejection was balanced by increased cerebral blood flow velocity during balloon inflation in diastole.
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Affiliation(s)
- A T Cheung
- Department of Anesthesia, University of Pennsylvania, Philadelphia 19104-4283, USA
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Cheung AT, Chen PC, Leshchinsky TV, Wiltse SL, Basadonna GP, Katznelson S, Perez RV. Improvement in conjunctival microangiopathy after simultaneous pancreas-kidney transplants. Transplant Proc 1997; 29:660-1. [PMID: 9123466 DOI: 10.1016/s0041-1345(96)00387-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- A T Cheung
- UCD Medical Center, Sacramento 95817, USA
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Abstract
PURPOSE Despite intense investigation of angiogenesis, little effort has been made to exploit this phenomenon in ischemic tissue. The few studies on this topic have focused primarily on the development of collateral arteries in existing arterial beds. A previous study showed that a perfused muscle flap transposed to an ischemic limb formed vascular connections, which were demonstrated with angiography, between the arteries of the flap and the limb vasculature. Microsphere studies suggested that these vascular connections increased the resting perfusion of the ischemic limb. This study is designed to confirm histologically that such connections develop and to quantitate the number and dimensions of these new vessels. METHODS Through a midline laparotomy, the right common iliac artery was ligated and divided in 18 male New Zealand white rabbits. An abdominal-wall muscle flap based on the left inferior epigastric artery was transposed to the right thigh. On the seventh day, contrast dye was injected into the flap artery of eight rabbits and an arteriogram was obtained. The tissue of the remaining rabbits was perfusion-fixed at 3 days (n = 2), 7 days (n = 4), and 14 days (n = 4). Thin sections of the flap-thigh muscle interface were stained with hematoxylin and eosin and for alpha-actin and proliferating cell nuclear antigen and were examined microscopically. RESULTS An arteriogram confirmed vascular connections between the flap and the native limb circulation in seven of the eight rabbits. Histologic evaluation of the flap-thigh muscle interface showed no new vessels on the third day. On the seventh day, 6.8 +/- 4.8 new vessels (positive alpha-actin staining, red blood cells in lumen) were seen per 40 x field; the vessels averaged 10.2 +/- 5.2 microns in diameter. On the fourteenth day, there were 7.3 +/- 3.8 vessels per 40 x field (p = 0.46), but the vessel diameter increased to 20.7 +/- 10.6 microns (p = 0.013). Proliferating cell nuclear antigen staining confirmed that these were proliferating vessels. CONCLUSION Within seven days, new vessels that were more mature than capillaries (stained for alpha-actin, a smooth muscle cell protein) formed between the flap and the thigh muscle. These new connecting vessels continue to enlarge in diameter between 7 and 14 days, but the stimulus to form new vessels appeared to decline or disappear before the fourteenth day. Attempts to sustain this phenomenon with angiogenic factors are underway.
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Affiliation(s)
- W C Pevec
- Department of Surgery, University of California, Davis Medical Center, Sacramento 95817, USA
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Stecker MM, Cheung AT, Patterson T, Savino JS, Weiss SJ, Richards RM, Bavaria JE, Gardner TJ. Detection of stroke during cardiac operations with somatosensory evoked responses. J Thorac Cardiovasc Surg 1996; 112:962-72. [PMID: 8873722 DOI: 10.1016/s0022-5223(96)70096-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVES The objectives of this study were to determine if monitoring of intraoperative somatosensory evoked potentials could be used to detect stroke during cardiac operations and to establish indicators of cerebral ischemia based on changes in these potentials. METHODS Twenty-five patients undergoing cardiac operations underwent preoperative and postoperative neurologic examinations as well as intraoperative recording of somatosensory evoked potentials. Detailed analysis of the waveforms of these potentials was performed. RESULTS Two of the 25 patients had intraoperative strokes. These patients and only these patients had changes in their somatosensory evoked potentials during the operation suggesting cerebral ischemia. The unilateral disappearance of the cortical somatosensory evoked potential waves correlated significantly with the clinical outcome of stroke (p < 0.004). Ischemic changes were detected in real time and were related to the removal of the aortic crossclamp in one patient and to the initiation of cardiopulmonary bypass in the other. CONCLUSIONS Somatosensory evoked potentials can detect intraoperative stroke during cardiac operations. Acute, unilateral decreases in amplitude of the cortical potential are more useful than changes in latency in detecting intraoperative stroke.
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Affiliation(s)
- M M Stecker
- Department of Neurology, University of Pennsylvania, Philadelphia, USA
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Abstract
Despite major advances in the management and care of critically ill and low-birth weight human and nonhuman primate infants over the past two decades, infection remains a major source of neonatal morbidity and mortality. Although the causes of enhanced susceptibility and dissemination of neonatal infections are incompletely defined in the literature, substantial evidence from this and other laboratories has implied that functional abnormalities of neonatal polymorphonuclear leukocytes (PMNs) may be a major contributor. Increased understanding of the functional characteristics of neonatal PMNs should, therefore, provide significant insight into the pathogenesis and possible therapy of infections in neonates. Our laboratory has been actively involved in evaluating the functional competence of PMNs in neonatal human and nonhuman primates. This report describes a study in which we have confirmed and characterized the functional compromises in neonatal PMNs of rhesus monkeys, including deficiencies in chemotaxis, membrane deformability, phagocytosis, and killing.
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Affiliation(s)
- A T Cheung
- Department of Medical Pathology, UC Davis School of Medicine, UC Davis Medical Center, Sacramento 95817, USA
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Affiliation(s)
- S J Weiss
- Department of Anesthesiology, University of Pennsylvania, Philadelphia, 19104-4283, USA
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Abstract
BACKGROUND Measuring the effects of intraaortic balloon counterpulsation (IABP) in single cardiac beats may permit an improved understanding of the physiologic mechanisms by which IABP improves the circulation. The objective of the study was to use trans- esophageal echocardiography in combination with hemodynamic measurements to test the hypothesis that IABP improves global left ventricular systolic function selectively in the IABP-augmented cardiac beats by acutely decreasing left ventricular afterload. METHODS Twenty-seven studies in which the IABP-to-R wave trigger ratio was serially changed from 1:1, 1:2, 1:4, 0:1 (IABP off) and back to 1:1 were performed in 20 anesthetized cardiac surgical patients during IABP support. Left ventricular short-axis end-diastolic cross-sectional area, end-systolic area, mean end-systolic wall thickness, and ejection time were measured by transesophageal echocardiography at the midpapillary muscle level. Aortic pressure was measured simultaneously from the central lumen of the intraaortic balloon catheter. These measurements were used to calculate the fractional area change, end-systolic meridional wall stress, and heart rate-corrected velocity of circumferential fiber shortening. The echocardiographic and hemodynamic parameters of left ventricular preload, afterload, and systolic function immediately after balloon deflation (IABP-augmented cardiac beats) were compared to the parameters measured during nonaugmented cardiac beats to determine the beat-to-beat effects of IABP on left ventricular function. RESULTS IABP-augmented cardiac beats had a decreased systolic arterial pressure and end-systolic meridional wall stress and increased diastolic blood pressure, fractional area change, and velocity of circumferential fiber shortening compared to nonaugmented cardiac beats. IABP did not cause significant beat-to-beat changes in heart rate, pulmonary artery diastolic pressure, or central venous pressure. The improvement in left ventricular systolic function associated with IABP-augmented cardiac beats correlated with the decrease in end-systolic meridional wall stress for that cardiac beat. CONCLUSIONS Beat-to-beat echocardiographic and hemodynamic measurements performed in anesthetized cardiac surgical patients during IABP support demonstrated improved left ventricular systolic function and decreased left ventricular systolic wall stress in the cardiac beats immediately after balloon deflation. The relationship between left ventricular systolic function and left ventricular systolic wall stress during IABP support suggests that afterload reduction was an important mechanism by which IABP instantaneously improved circulatory function in anesthetized cardiac surgical patients.
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Affiliation(s)
- A T Cheung
- Department of Anesthesiology, Division of Cardiothoracic Anesthesia, University of Pennsylvania, Philadelphia, 19104-4283, USA
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Cheung AT, Savino JS, Weiss SJ, Patterson T, Richards RM, Gardner TJ, Stecker MM. Detection of acute embolic stroke during mitral valve replacement using somatosensory evoked potential monitoring. Anesthesiology 1995; 83:208-10. [PMID: 7605001 DOI: 10.1097/00000542-199507000-00026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- A T Cheung
- Department of Anesthesiology, University of Pennsylvania, Philadelphia 19104-4283, USA
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Ahlfors CE, Alley PA, Bry WI, Cheung AT, Cox KL. Plasma fluorescein binding and transcapillary fluorescein escape rate in renal failure associated with diabetes. Am J Kidney Dis 1995; 25:543-7. [PMID: 7702048 DOI: 10.1016/0272-6386(95)90121-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Microvascular damage, often resulting in renal failure, is a common complication of diabetes. Transcapillary fluorescein escape rate (TCFER) as monitored by intravital microscopy has been used as an indicator of the extent of capillary damage in diabetes and to assess improvement in microvascular function after combined kidney-pancreas transplant. However, fluorescein anion binds to plasma albumin, and albumin-ligand binding may be altered in the presence of renal disease. The purpose of this study was to compare fluorescein binding by plasma from diabetics with renal failure with plasma from healthy nondiabetics. Fluorescein binding by plasma from seven type I diabetics awaiting kidney-pancreas transplant and seven healthy adults of similar age and sex was studied using ultrafiltration and dialysis. There was no significant difference in the apparent albumin binding of fluorescein at physiologically relevant fluorescein concentrations, even though the TCFER was significantly increased in the diabetics as compared with the controls. Hippurate, a ligand that accumulates in renal failure, did alter fluorescein binding in a defatted albumin solution but not sufficiently to account for the differences in TCFERs. These data indicate that impaired albumin binding of fluorescein does not contribute significantly to the TCFER in diabetics with renal failure.
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Affiliation(s)
- C E Ahlfors
- Department of Pediatrics, California Pacific Medical Center Research Institute, San Francisco 94118, USA
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Abstract
Mitral valve replacement was performed urgently in a patient with hemorrhagic brain lesions. To decrease the risk of intracranial hemorrhage, cardiopulmonary bypass was performed using a heparin-coated perfusion system and a reduced dose of heparin. The detection of an acute intracardiac thrombus by transesophageal echocardiography during cardiopulmonary bypass exposed a potential hazard of techniques employing reduced systemic anticoagulation for cardiac operations.
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Affiliation(s)
- A T Cheung
- Department of Anesthesia, University of Pennsylvania, Philadelphia 19104-4293
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Cheung AT, Savino JS, Weiss SJ, Aukburg SJ, Berlin JA. Echocardiographic and hemodynamic indexes of left ventricular preload in patients with normal and abnormal ventricular function. Anesthesiology 1994; 81:376-87. [PMID: 8053588 DOI: 10.1097/00000542-199408000-00016] [Citation(s) in RCA: 237] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Transesophageal echocardiography (TEE) is used to diagnose hypovolemia despite the lack of validation studies. The objective was to determine the effects of acute graded hypovolemia on TEE and conventional hemodynamic determinants of left ventricular (LV) preload in anesthetized patients with normal and abnormal LV function. METHODS Determinants of LV preload derived from TEE and hemodynamic monitoring were measured serially in 35 anesthetized cardiac surgical patients without valvular heart disease. Patients were stratified into two groups: those with normal LV function (group 1, n = 17) and those with LV wall motion abnormalities (group 2, n = 13). Patients in groups 1 and 2 were subjected to graded hypovolemia produced by collecting 6 aliquots of blood, each equal to 2.5% of their estimated blood volume (EBV). A third group of patients (group 3, n = 5), not subjected to graded hypovolemia, were studied to test for time-dependent changes. RESULTS Group 2 had a significantly greater baseline (mean +/- SD) pulmonary artery occlusion pressure (17 +/- 6 vs. 11 +/- 6 mmHg), LV end-diastolic area (23 +/- 5 vs. 18 +/- 4 cm2), LV end-diastolic wall stress (23 +/- 10 vs. 14 +/- 6 x 10(3) dyne.cm-2), and smaller fractional area change (35 +/- 13 vs. 59 +/- 7%). In groups 1 and 2, the LV end-diastolic area, pulmonary artery occlusion pressure, and LV end-diastolic wall stress decreased linearly in response to blood loss in the range of 0-15% of the EBV. No significant changes in the measured parameters occurred in group 3. A significant decrease in the central venous pressure, pulmonary artery occlusion pressure, and LV end-diastolic area was detected in response to a 2.5% EBV deficit (approximately 1.75 ml.kg-1) in groups 1 and 2. The mean change in LV end-diastolic area (0.3 cm2/1.0% EBV deficit) in response to equivalent EBV deficits was the same in groups 1 and 2. In contrast, the mean change in cardiac output and LV end-diastolic wall stress was less in group 2 despite a greater decrease in pulmonary artery occlusion pressure. Compared to group 1, a greater EBV deficit (7.5% to 12.5% vs. 2.5% to 5%) was required in group 2 to cause a significant decrease in the cardiac output, stroke volume, mixed venous oxygen saturation, and LV end-diastolic wall stress. CONCLUSIONS TEE and hemodynamic determinants of LV preload detected changes in LV function caused by acute blood loss. Acute blood loss caused directional changes in LV end-diastolic area, pulmonary artery occlusion pressure, and LV end-diastolic wall stress even in patients with LV wall motion abnormalities. Changes in LV end-diastolic wall stress, derived from both TEE and hemodynamic measurements corresponded to changes in cardiac output, stroke volume, and mixed venous oxygen saturation that occurred during acute blood loss.
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Affiliation(s)
- A T Cheung
- Department of Anesthesiology, University of Pennsylvania, Philadelphia 19104-4283
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Cheung AT, Perez RV, Basadonna GP, Cox KL, Bry WI. Microangiopathy reversal in successful simultaneous pancreas-kidney transplantation. Transplant Proc 1994; 26:493-5. [PMID: 8171520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- A T Cheung
- Department of Pathology (PAT-1), University of California-Davis Medical Center, Sacramento 95817
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Affiliation(s)
- J S Savino
- Hospital of the University of Pennsylvania, Philadelphia 19104-4283
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Cheung AT, Moss RB, Kurland G, Leong AB, Novick WJ. Chronic Pseudomonas aeruginosa endobronchitis in rhesus monkeys: II. A histopathologic analysis. J Med Primatol 1993; 22:257-62. [PMID: 8230177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have recently established a rhesus monkey model of chronic Pseudomonas aeruginosa (PA) endobronchitis by bronchoscopic instillation of PA-embedded agar beads. All experimental animals developed chronic neutrophilic endobronchitis similar to chronic PA endobronchitis in cystic fibrosis (CF). Histopathologic studies further confirmed similarities to chronic PA endobronchitis in CF, including marked peribronchial inflammation, epithelial damage, presence of degraded cilia and ciliary abnormalities, appearance of PA bacterial clusters, mucosal hyperplasia, goblet cell hypertrophy/hypersecretion, airway obstruction, alveolar abnormalities, bronchiectasis, and fibrosis.
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Affiliation(s)
- A T Cheung
- Department of Medical Pathology, University of California, Davis School of Medicine, Sacramento
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Cheung AT, Cox KL, Ahlfors CE, Bry WI. Reversal of microangiopathy in long-term diabetic patients after successful simultaneous pancreas-kidney transplants. Transplant Proc 1993; 25:1310-3. [PMID: 8442124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- A T Cheung
- Department of Pathology, University of California Davis Medical Center, Sacramento 95817
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