Outcomes of emergency endovascular versus open repair for abdominal aortic aneurysm rupture

Purpose

Ruptured abdominal aortic aneurysm (rAAA) is one of the most common aortic emergencies in vascular surgery and is associated with high operative mortality and morbidity rates despite recent treatment advances. We evaluated operative mortality risks for the outcomes of emergency endovascular aneurysm repair (eEVAR) vs. open repair in rAAA.

Methods

Twenty patients underwent eEVAR (n = 12) or open repair (n = 8) for rAAA between 2016 and 2020. We adopted the EVAR first strategy since 2018. Primary endpoints included in-hospital mortality and 1-year survival. The outcome variables were analyzed with Fisher exact, Mann-Whitney test, and linear by linear association. The Kaplan-Meier method was used to estimate survival.

Results

There were 13 males (65.0%) and the median age of the study cohort was 78.0 years (range, 49–88 years). In-hospital mortality occurred in 7 patients (35.0%); 5 (50.0%) in the early period and 2 (20.0%) in the later period of this series. According to the procedure type, 4 (50.0%) and 3 (25.0%) in-hospital mortalities occurred in the open repair and eEVAR patients, respectively. In 6 patients (50.0%), eEVAR was performed on unfavorable anatomy. The 1-year survival of eEVAR vs. open repair group was 75% ± 12.5% and 50% ± 17.7%, respectively. On univariate analysis, preoperative high-risk indices, postoperative acute renal failure requiring dialysis, pulmonary complications, and prolonged mechanical ventilation were associated with higher operative mortality.

Conclusion

The current data showed relatively superior outcomes with eEVAR vs. open repair for rAAA, even in some patients with unfavorable anatomy supporting the feasibility, efficacy, and safety of EVAR first strategy.

Guidelines for Transcatheter Aortic Valve Replacement in Korea: Past Obstacles and Future Perspectives

Background

Analyses of the efficacy and safety of transcatheter aortic valve replacement (TAVR) in most countries have been based on outcomes obtained in accordance with national practice guidelines and monitoring protocols. The purpose of this study is to share our experience regarding the process for establishing guidelines and monitoring protocols for the use of TAVR in Korea, in the hopes that it may be helpful to others undergoing a similar process in their own country.

Methods

The Korean guidelines for TAVR were established on June 1, 2015 in through a tri-party agreement involving the Department of Health and Welfare, the Korean Society of Thoracic and Cardiovascular Surgery and the Korean Society of Cardiology. We agreed to monitor the guidelines transparently and to exchange opinions regarding amendments or continuation of its contents after 3 years of monitoring.

Results

The monitoring meetings were not held as regularly as agreed, and monitoring was also made difficult by insufficient and incomplete data. Nevertheless, during the meetings, measures to improve the monitoring process were discussed, and accordingly, an agreement was made to continue the monitoring process, with the aim of completing data collection by 2018.

Conclusion

Compliance with guidelines is critical for assessing the efficacy and safety of TAVR. Moreover, the TAVR monitoring process must be properly conducted for an accurate evaluation to be made. Any country planning to introduce TAVR may encounter difficulties with regards to the optimal initiation strategy and subsequent monitoring. Nevertheless, continued efforts should be made to persuade the government and the corresponding medical societies to facilitate the optimal application of TAVR.

PAI-1 gain-of-function genotype, factors increasing PAI-1 levels, and airway obstruction: The GALA II Cohort

BACKGROUND

PAI-1 gain-of-function variants promote airway fibrosis and are associated with asthma and with worse lung function in subjects with asthma.

OBJECTIVE

We sought to determine whether the association of a gain-of-function polymorphism in plasminogen activator inhibitor-1 (PAI-1) with airway obstruction is modified by asthma status, and whether any genotype effect persists after accounting for common exposures that increase PAI-1 level.

METHODS

We studied 2070 Latino children (8-21y) with genotypic and pulmonary function data from the GALA II cohort. We estimated the relationship of the PAI-1 risk allele with FEV1/FVC by multivariate linear regression, stratified by asthma status. We examined the association of the polymorphism with asthma and airway obstruction within asthmatics via multivariate logistic regression. We replicated associations in the SAPPHIRE cohort of African Americans (n=1056). Secondary analysis included the effect of the at-risk polymorphism on postbronchodilator lung function.

RESULTS

There was an interaction between asthma status and the PAI-1 polymorphism on FEV₁ /FVC (P=.03). The gain-of-function variants, genotypes (AA/AG), were associated with lower FEV₁ /FVC in subjects with asthma (β=-1.25, CI: -2.14,-0.35, P=.006), but not in controls. Subjects with asthma and the AA/AG genotypes had a 5% decrease in FEV₁ /FVC (P<.001). In asthmatics, the risk genotype (AA/AG) was associated with a 39% increase in risk of clinically relevant airway obstruction (OR=1.39, CI: 1.01, 1.92, P=.04). These associations persisted after exclusion of factors that increase PAI-1 including tobacco exposure and obesity.

CONCLUSIONS AND CLINICAL RELEVANCE

The decrease in the FEV₁ /FVC ratio associated with the risk genotype was modified by asthma status. The genotype increased the odds of airway obstruction by 75% within asthmatics only. As exposures known to increase PAI-1 levels did not mitigate this association, PAI-1 may contribute to airway obstruction in the context of chronic asthmatic airway inflammation.

Caveolin-1 serves as a negative effector in senescent human gingival fibroblasts during Fusobacterium nucleatum infection

It is well established that aging is associated with increased susceptibility to infectious diseases. Fusobacterium nucleatum is a well-known bacterial species that plays a central bridging role between early and late colonizers in the human oral cavity. Further, the ability of F. nucleatum to invade gingival fibroblasts (GFs) is critical to the development of periodontal diseases. However, the mechanisms underlying the age-related infection of GFs by F. nucleatum remain unknown. We used young (fourth passage) and senescent (22nd passage) GFs to investigate the mechanisms of F. nucleatum infection in aged GFs and first observed increased invasion of F. nucleatum in senescent GFs. We also found that the co-localization of caveolin-1 (Cav-1), a protein marker of aging, with F. nucleatum and the knockdown of Cav-1 in GFs reduced F. nucleatum invasion. Additionally, F. nucleatum infection triggered the production of reactive oxygen species (ROS) through activation of NADPH oxidase in GFs, but senescent GFs exhibited significantly lower levels of NADPH oxidase activity and ROS production compared with young GFs in both the uninfected and infected conditions. Also, senescent GFs exhibited a decline in proinflammatory cytokine production and extracellular signal regulated kinase (ERK) phosphorylation following F. nucleatum infection. Interestingly, the knockdown of Cav-1 in senescent GFs increased NADPH oxidase activity and caused the upregulation of interleukin-6 and interleukin-8 and the phosphorylation of ERK. Collectively, the increased expression of Cav-1 might play a critical role in F. nucleatum invasion and could hinder the host response in senescent GFs.

Maternal age and asthma in Latino populations

BACKGROUND

Younger maternal age at birth is associated with increased risk of asthma in offspring in European descent populations, but has not been studied in Latino populations.

OBJECTIVES

We sought to examine the relationship between maternal age at birth and prevalence of asthma in a nationwide study of Latino children.

METHODS

We included 3473 Latino children aged 8-21 years (1696 subjects with physician-diagnosed asthma and 1777 healthy controls) from five US centres and Puerto Rico recruited from July 2008 through November 2011. We used multiple logistic regression models to examine the effect of maternal age at birth on asthma in offspring overall and in analyses stratified by ethnic subgroup (Mexican American, Puerto Rican and other Latino). Secondary analyses evaluated the effects of siblings, acculturation and income on this relationship.

RESULTS

Maternal age < 20 years was significantly associated with decreased odds of asthma in offspring, independent of other risk factors (OR = 0.73, 95% CI: 0.57-0.93). In subgroup analyses, the protective effect of younger maternal age was observed only in Mexican Americans (OR = 0.53, 95% CI: 0.36, 0.79). In Puerto Ricans, older maternal age was associated with decreased odds of asthma (OR = 0.65, 95% CI: 0.44-0.97). In further stratified models, the protective effect of younger maternal age in Mexican Americans was seen only in children without older siblings (OR = 0.44, 95% CI: 0.23-0.81).

CONCLUSION AND CLINICAL RELEVANCE

In contrast to European descent populations, younger maternal age was associated with decreased odds of asthma in offspring in Mexican American women. Asthma is common in urban minority populations but the factors underlying the varying prevalence among different Latino ethnicities in the United States is not well understood. Maternal age represents one factor that may help to explain this variability.

Novel genetic risk factors for asthma in African American children: Precision Medicine and the SAGE II Study

Asthma, an inflammatory disorder of the airways, is the most common chronic disease of children worldwide. There are significant racial/ethnic disparities in asthma prevalence, morbidity, and mortality among US children. This trend is mirrored in obesity, which may share genetic and environmental risk factors with asthma. The majority of asthma biomedical research has been performed in populations of European decent. We sought to identify genetic risk factors for asthma in African American children. We also assessed the generalizability of genetic variants associated with asthma in European and Asian populations to African American children. Our study population consisted of 1227 (812 asthma cases, 415 controls) African American children with genome-wide single nucleotide polymorphism (SNP) data. Logistic regression was used to identify associations between SNP genotype and asthma status. We identified a novel variant in the PTCHD3 gene that is significantly associated with asthma (rs660498, p = 2.2 × 10(-7)) independent of obesity status. Approximately 5 % of previously reported asthma genetic associations identified in European populations replicated in African Americans. Our identification of novel variants associated with asthma in African American children, coupled with our inability to replicate the majority of findings reported in European Americans, underscores the necessity for including diverse populations in biomedical studies of asthma.

Clinical significance of cerebrovascular complications in patients with acute infective endocarditis: a retrospective analysis of a 12-year single-center experience

BACKGROUND

Cerebrovascular complications (CVCs) frequently occur in patients with acute infective endocarditis (IE). The aim of this study is to describe the clinical findings of CVCs and to evaluate the impact of CVCs on long-term mortality in patients with IE.

METHODS

We retrospectively analyzed 144 patients who fulfilled the modified Duke's criteria for definite left-sided IE. CVCs were classified into minor (silent cerebral embolism, TIA and stroke with an initial modified Rankin scale ≤ 2) or major (an initial modified Rankin scale ≥ 3) CVCs. Cox proportional hazards model was used for mortality analysis. Hazard ratio (HR) and 95% confidence interval (CI) were obtained.

RESULTS

The mean age of the 144 patients (96 males and 48 females) was 49.1 years (range 6-85 years). A CVC was found in 37 (25.7%) patients. Of these, 25 were treated with surgical therapy. The patients who underwent early surgery within 2 weeks after stroke had a statistical trend toward a higher risk of postoperative brain hemorrhage (50% versus 4.8%, P = 0.057 by Fisher exact test). The minor CVC group had a similar risk of death as the no-CVC group (P = 0.803; HR 0.856; CI 0.253-2.894), whereas the major CVC group had a higher mortality (P = 0.013; HR 2.865; CI 1.254-6.548) than the no-CVC group. In the multivariate analysis, major CVC (P = 0.002; HR 3.893; CI 1.649-9.194) was a significant predictor of mortality in IE patients, together with advanced age (P = 0.005; HR 3.138; CI 1.421-6.930) and prosthetic valve IE (P = 0.008; HR 2.819; CI 1.315-6.044).

CONCLUSIONS

IE can give rise to various forms of CVC, most frequently, acute ischemic brain lesions. In our study, major CVC was associated with high risk of mortality although total CVC was not significantly related to the risk of death in patients with IE.

Eleven years of experience with the neurologic complications in Korean patients with acute aortic dissection: a retrospective study

Background

This study attempts to explore the clinical features, possible mechanisms and prognosis of the neurologic complications in patients with acute aortic dissection (AD).

Methods

Medical records of 278 consecutive patients with AD (165 with type A and 113 with type B dissection) over 11.5 years were retrospectively analyzed for clinical history, CT findings, neurologic complications and outcome. Neurologic complications were classified into early-onset or delayed-onset complications. Independent t-test or Chi-square test (or Fisher exact test) was used for comparing the different groups. Multivariable logistic regression analysis was performed to determine the independent association between variables.

Results

The mean age of the included patients (145 male and 133 female) was 59.4 years (range 19–91 years). 41 patients (14.7%) had a neurologic complication, which included 21 with early-onset complication and 23 with delayed-onset complication, including 3 with both. Advanced age and classic type of dissection were independently associated with the neurologic complication in patients with type A dissection. The most frequent manifestation was ischemic stroke (26 patients, 9.4%), followed by hypoxic encephalopathy (9, 3.2%), ischemic neuropathy (5, 1.8%), spinal cord ischemia (5, 1.8%), seizure (2, 0.7%), hoarseness (1, 0.4%) and septic encephalopathy (1, 0.4%). Overall in-hospital mortality was 10.1%, whereas the complicated group had a mortality rate of 43.9%. Renal impairment, pulse deficit, neurologic complication and nonsurgical treatment were independent variables for determining in-hospital mortality in patients with type A dissection.

Conclusions

The dominance of neurologic symptom in the early stage of AD may make its early diagnosis difficult. Besides chest pain and widened mediastinum in chest x-ray, variable neurologic symptoms including left hemiparesis with asymmetric pulse and hypotension may suggest underlying AD.

Eleven years' experience with Korean cardiac myxoma patients: focus on embolic complications

BACKGROUND

Cardiac myxomas are rare but are the most common cardiac tumors. This study is based on our clinical experience with cardiac myxomas over a period of 11 years at Sejong General Hospital. We focused on the embolic complications of patients with cardiac myxoma.

METHODS

We retrospectively reviewed the medical records of 59 consecutive patients with cardiac myxoma who were treated between January 2000 and March 2011. The myxomas were divided into two types: type 1, with an irregular or villous surface and a soft consistency, and type 2, with a smooth surface and a compact consistency. The 59 investigated patients were classified into the embolic group and the non-embolic group.

RESULTS

Cardiac obstructive symptoms, embolic events and constitutional symptoms were observed in 37 (62.7%), 13 (22.0%) and 10 (16.9%) patients, respectively. When the embolic and non-embolic groups were compared, there were no significant differences in vascular risk factors, the ejection fraction, the left atrial diameter or the tumor size. However, type 1 myxomas were significantly more frequent in the embolic group (p = 0.009 by Fisher's exact test). A binary logistic regression analysis showed that type 1 pathology alone was independently associated with myxoma-related embolism (p = 0.008; odds ratio 10.056; 95% confidence interval 1.828-55.337). There were no operative deaths in any of the 59 patients studied. Among the 13 patients with embolism, 11 (84.6%) had brain infarcts. The main patterns of the lesions were multiple lesions (8 out of 11 patients, 72.7%) and lesions in the middle cerebral artery territories (7 out of 11 patients, 63.6%). The other 2 patients were found to have occlusion of the left central retinal artery and left external iliac artery. Additionally, incidental cerebral aneurysms were found in the latter case. There was no recurrence of myxoma or myxoma-related symptoms in the 53 patients receiving outpatient management during the follow-up period (range 2 months to 11 years).

CONCLUSIONS

The embolic potential of myxoma was associated with an irregular surface pathology but not with vascular risk factors. Echocardiography should be performed in patients with embolic events, especially when cerebral infarcts with multiple territorial lesions are detected. Surgical resection is a relatively safe and curative procedure for cardiac myxoma.

Neurodegeneration and early lethality in superoxide dismutase 2-deficient mice: a comprehensive analysis of the central and peripheral nervous systems

The contribution of oxidative stress to diabetic complications including neuropathy is widely known. Mitochondrial and cellular damage are associated with the overproduction of reactive oxygen species and decreased levels or function of the cellular antioxidant mitochondrial manganese superoxide dismutase (SOD2). We hypothesized that targeted SOD2 deletion in the peripheral nervous system using cre-lox technology under control of the nestin promoter would accelerate neuropathy in a type 2 model of diabetes, the BKS.db/db mouse. SOD2-deficient mice, however, demonstrated severe gait deformities and seizures and died by 20 days of age. Examination of SOD2 expression levels revealed that SOD2 was lost in brain and reduced in the spinal cord, but appeared normal in dorsal root ganglia and peripheral nerves in SOD2-deficient mice. These findings indicate incomplete targeted knockout of SOD2. Morphological examination revealed cortical lesions similar to spongiform encephalopathy in the brain of SOD2-deficient mice. No lesions were evident in the spinal cord, but changes in myelin within the sciatic and sural nerves including a lack of cohesion between layers of compact myelin were observed. Together, these results indicate that targeted neuronal SOD2 knockout using the nestin promoter results in severe central nervous system degeneration and perinatal lethality in mice. A specific peripheral nervous system-targeting construct is required to examine the consequences of SOD2 knockout in diabetic neuropathy.

Preoperative Extracorporeal Membrane Oxygenation for Severe Ischemic Mitral Regurgitation - 2 case reports -

Indication for extracorporeal membrane oxygenation (ECMO) has been extended as the experience of ECMO in various clinical settings accumulates and the outcome after ECMO installation improves. We report two cases of successful mitral valve surgery for severe ischemic mitral regurgitation in patients on ECMO support for cardiogenic shock which developed upon coronary angiography.

The detection of pulmonary embolisms after a coronary artery bypass graft surgery by the use of 64-slice multidetector CT

The purpose of this study was to examine the incidence of pulmonary embolism (PE) after a coronary artery bypass graft (CABG) using 64-slice multidetector CT (MDCT), and to determine the correlations between the occurrence of a PE and the clinical or surgical parameters. Three hundred and twenty-six consecutive patients, who underwent coronary CT angiography using 64-slice MDCT to assess the graft patency after CABG, were enrolled in this study. Additional axial CT images, which were reconstructed by adopting a large field of view and thinner image slices, were reviewed for the presence of PE. The relationship between the occurrence of a PE and the type of surgery (off-pump CABG versus conventional CABG), number of target vessels, use of a saphenous vein graft, and length of stay in the intensive care unit (ICU) were evaluated. PE was detected on the CT images of 33 patients (10.1%), which involved the lobar or more proximal arteries in seven patients and the segmental or subsegmental arteries in 26. PE occurred more frequently after off-pump CABG (16.5%, 14/85) than after conventional CABG (7.9%, 19/241) (P = 0.024). Patients with PE were older (67 years vs. 62.7 years) and had longer stays in the ICU (5.6 days vs. 3.8 days) than those without (P = 0.013 and P = 0.007, respectively). No significant difference was observed in the number of target vessels and use of a saphenous vein graft between patients with and without an embolism. In a multi-variable analysis, the age of the patient, surgical methods, and ICU stay were independent predictors for the occurrence of PE (P = 0.013, P = 0.017, and P = 0.005, respectively). MDCT helps detect PE in patients after CABG. It is encountered more frequently after off-pump CABG than after conventional CABG and in older patients with longer ICU stays.

Short- and long-term results of triple valve surgery: a single center experience

Triple valve surgery is usually complex and carries a reported operative mortality of 13% and 10-yr survival of 61%. We examined surgical results based on our hospital's experience. A total of 160 consecutive patients underwent triple valve surgery from 1990 to 2006. The most common aortic and mitral valve disease was rheumatic disease (82%). The most common tricuspid valve disease was functional regurgitation (80%). Seventy-four percent of the patients were in New York Heart Association (NYHA) class III and IV. Univariate and multivariable analyses were performed to identify predictors of early and late survival. Operative mortality was 6.9% (n=11). Univariate factors associated with mortality included old age, preoperative renal failure, postoperative renal failure, pulmonary complications, and stroke. Of them, postoperative renal failure and stroke were associated with mortality on multivariable analysis. Otherwise, neither tricuspid valve replacement nor reoperation were statistically associated with late mortality. Survival at 5 and 10 yr was 87% and 84%, respectively. Ninety-two percent of the patients were in NYHA class I and II at their most recent follow-up. Ten-year freedom from prosthetic valve endocarditis was 97%; from anticoagulation-related hemorrhage, 82%; from thromboembolism, 89%; and from reoperation, 84%. Postoperative renal failure and stroke were significantly related with operative mortality. Triple valve surgery, regardless of reoperation and tricuspid valve replacement, results in acceptable long-term survival.

Off-pump total left anterior descending area re-vascularisation using left internal thoracic artery auto Y graft; angiographic early and 3-year follow-up results

BACKGROUND

We evaluated the efficacy of a well-prepared left internal thoracic artery (LITA) auto Y graft for simultaneous left anterior descending artery (LAD) and diagonal artery (DA) re-vascularisation in selected patients for the reduction of the number of required grafts and improved graft patency, while limiting technical problems.

METHODS

Twenty well-controlled diabetic patients, mean age 62.8+/-8.3, 17 males and three females, underwent isolated elective off-pump coronary artery bypass grafting using the LITA auto Y graft from July 2003 to August 2004.

RESULTS

In-hospital data and angiographic results at 6 months after the surgery showed that there was no early mortality, early graft failure and major morbidity except for two cases of superficial wound infection. The 3-year follow-up results including angiographic findings (mean of 37+/-3.3-month follow-up) demonstrated that all patients are alive and have excellent graft patency in both the LAD and DA. Only two cases required right coronary artery (RCA) stenting during the follow-up period. Compared with our previous routine LITA composite Y graft technique, it is assumed that LITA auto Y graft technique may reduce the number of mobilised conduits or avoided sequential anastomosis.

CONCLUSIONS

This small study showed that our technique is technically feasible and may be safely performed to the selective patients. The LITA auto Y graft might be an additional surgical option, in terms of not only preserving the other grafts and maintaining patency in the LAD area bypass, but also preventing the need for sequential anastomoses.

Host receptors in malaria merozoite invasion

The clinical manifestations of Plasmodium falciparum malaria are directly linked to the blood stage of the parasite life cycle. At the blood stage, the circulating merozoites invade erythrocytes via a specific invasion pathway often identified with its dependence or independence on sialic acid residues of the host receptor. The invasion process involves multiple receptor-ligand interactions that mediate a complex series of events in a period of approximately 1 min. Although the mechanism by which merozoites invade erythrocytes is not fully understood, recent advances have put a new perspective on the importance of developing a multivalent blood stage-malaria vaccine. In this review, we highlight the role of currently identified host invasion receptors in blood-stage malaria.

Outcome of the modified maze procedure for atrial fibrillation combined with rheumatic mitral valve disease using cryoablation

This study evaluated the mid-term results of the modified maze procedure using cryoablation for treating atrial fibrillation associated with rheumatic mitral valve disease. Between March 2000 and February 2004, 177 consecutive patients underwent the modified maze procedure using cryoablation concomitant with mitral valve surgery, were divided into the modified Cox-Maze III (group CM, n=88), modified Kosakai-Maze (group KM, n=63) and left atrial maze (group LA, n=26) procedures. Postoperative and follow-up results were analyzed and compared between the groups, with a mean follow-up time of 22.4+/-15.1 months. There were three hospital deaths (1.7%). The operative time was significantly longer in the group CM than the KM or LA groups, respectively. One late death developed in the CM group. At last follow-up, 139 patients had sinus rhythm (79.9%), which was regained in 67 CM (77.9%), 50 KM (80.7%) and 22 (84.6%) LA group (P=0.743) patients. Freedom from stroke at 4 years was 84.6% in the CM, 95.0% in the KM, and 92.9% in the LA (P=0.916) groups. There were no significant differences in the sinus conversion or stroke rate between patients with the left atrial appendage preserved and those with it excised or obliterated. The modified maze procedure using cryoablation is safe and effective, with an acceptable sinus conversion rate and clinical improvement.

Application of cabrol technique to off-pump coronary artery bypass grafting using radial artery

We present the case of a Cabrol-type proximal anastomosis technique in off-pump coronary artery bypass. The patient was a 64-year-old man with significant stenoses on the left main, left anterior descending, and proximal right coronary artery. The obtuse marginal and right coronary arteries were anastomosed with both ends of a radial artery. For the proximal anastomosis during this procedure, we applied the Cabrol-type looping interposition technique. In selected patients, we suggest that this technique allows the effective use of graft length and can reduce a number of ascending aortic manipulations.

Interferon gamma stimulates beta-secretase expression and sAPPbeta production in astrocytes

Neurons, but not astrocytes, are known as the major source of Abeta, because astrocytes express low levels of putative beta-secretase (BACE). Astrocytes near senile plaque cores show enhanced levels of BACE protein expression, however, suggesting that astrocytes can contribute to Abeta production under pathological conditions. To investigate factors that stimulate BACE protein expression in astrocytes, we tested the effects of interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) on BACE protein expression in U373MG astrocytoma cells and primary astrocyte cultures from Tg2576 mouse brains. BACE protein expression and sAPPbeta production were dramatically increased, without changes in holo APP levels, following IFN-gamma treatment in both cell types. AG490, which is a blocker of IFN-gamma-induced STAT signaling, decreased IFN-gamma-induced BACE protein expression and sAPPbeta production in a dose-dependent manner. These results show that astrocytes are capable of expressing BACE and producing sAPPbeta in response to certain stimulating factors, and IFN-gamma is one such factor.

A case of localized persistent interstitial pulmonary emphysema

Interstitial pulmonary emphysema is a well-documented complication of assisted mechanical ventilation in premature infants with respiratory distress syndrome. Localized persistent interstitial pulmonary emphysema (LPIPE) confined to a single lobe was incidentally presented in a 4-day-old female infant. This patient was a normal full-term baby with no respiratory distress symptom and no experience of assisted mechanical ventilation. Chest radiograph showed radiolucent area in right lower lobe zone, which needed differential diagnosis from other congenital lesions such as congenital cystic adenomatoid malformation and congenital lobar emphysema. CT scan showed irregular-shaped air cystic spaces and pathologically, cystic walls primarily consisted of compressed lung parenchyma and loose connective tissue intermittently lined by multinucleated foreign body giant cells.

Plasmodium falciparum erythrocyte membrane protein 1 is anchored to the actin-spectrin junction and knob-associated histidine-rich protein in the erythrocyte skeleton

A distinctive pathological feature of Plasmodium falciparum malaria is the endothelial attachment of erythrocytes infected with mature asexual-stage parasites in microvessels of the major organs. Electron-dense protrusions described as knobs are displayed on the surface of parasitized erythrocytes and act as attachment points in cytoadherence. Parasite-encoded knob-associated histidine-rich protein (KAHRP) is a major component of knobs found on the cytoplasmic side of the host cell membrane. P. falciparum erythrocyte membrane protein 1 (PfEMP1) is a family of parasite-encoded cytoadherence receptors localized to knobs on the surface of parasitized erythrocytes. Despite its high antigenic diversity, PfEMP1 has a remarkably conserved cytoplasmic domain. We demonstrate in this study that the cytoplasmic domain of PfEMP1 (VAR(CD)) binds to host spectrin and actin and to full-length KAHRP in vitro. Apparent dissociation constants determined for VAR(CD)/F-actin and VAR(CD)/KAHRP interactions are 44.9+/-6.4 and 10. 7+/-2.2 nM, respectively. Further, we provide evidence that KAHRP polypeptides self-associate in solution to form structures similar to knobs and show binding of self-associated KAHRP clusters to spectrin-actin-protein 4.1 complexes. Findings in this study suggest that PfEMP1 is localized to the knob in P. falciparum-infected erythrocytes by binding to the host spectrin-actin junction and to self-associated KAHRP through its conserved cytoplasmic domain.

Altered membrane proteins and permeability correlate with cardiac dysfunction in cardiomyopathic hamsters

A mutation in the delta-sarcoglycan (SG) gene with absence of delta-SG protein in the heart has been identified in the BIO14.6 cardiomyopathic (CM) hamster, but how the defective gene leads to myocardial degeneration and dysfunction is unknown. We correlated left ventricular (LV) function with increased sarcolemmal membrane permeability and investigated the LV distribution of the dystrophin-dystroglycan complex in BIO14.6 CM hamsters. On echocardiography at 5 wk of age, the CM hamsters showed a mildly enlarged diastolic dimension (LVDD) with decreased LV percent fractional shortening (%FS), and at 9 wk further enlargement of LVDD with reduction of %FS was observed. The percent area of myocardium exhibiting increased membrane permeability or membrane rupture, assessed by Evans blue dye (EBD) staining and wheat germ agglutinin, was greater at 9 than at 5 wk. In areas not stained by EBD, immunostaining of dystrophin was detected in CM hamsters at sarcolemma and T tubules, as expected, but it was also abnormally expressed at the intercalated discs; in addition, the expression of beta-dystroglycan was significantly reduced compared with control hearts. As previously described, alpha-SG was completely deficient in CM hearts compared with control hearts. In myocardial areas showing increased sarcolemmal permeability, neither dystrophin nor beta-dystroglycan could be identified by immunolabeling. Thus, together with the known loss of delta-SG and other SGs, abnormal distribution of dystrophin and reduction of beta-dystroglycan are associated with increased sarcolemmal permeability followed by cell rupture, which correlates with early progressive cardiac dysfunction in the BIO14.6 CM hamster.

Human homologue of the Drosophila discs large tumor suppressor binds to p56lck tyrosine kinase and Shaker type Kv1.3 potassium channel in T lymphocytes

Human homologue of the Drosophila discs large tumor suppressor protein (hDlg) belongs to a newly discovered family of proteins termed MAGUKs that appear to have structural as well as signaling functions. Consistent with the multi-domain organization of MAGUKs, hDlg consists of three copies of the PDZ (PSD-95/Discs large/zO-1) domain, an SH3 motif, and a guanylate kinase-like domain. In addition, the hDlg contains an amino-terminal proline-rich domain that is absent in other MAGUKs. To explore the role of hDlg in cell signaling pathways, we used human T lymphocytes as a model system to investigate interaction of hDlg with known tyrosine kinases. In human T lymphocyte cell lines, binding properties of hDlg were studied by immunoprecipitation, immunoblotting, and immune complex kinase assays. Our results show that protein tyrosine kinase activity is associated with the immunoprecipitates of hDlg. Immunoblotting experiments revealed that the immunoprecipitates of hDlg contain p56lck, a member of the Src family of tyrosine kinases. The specificity of the interaction is demonstrated by the lack of p59fyn tyrosine kinase and phosphotidylinositol 3-kinase in the hDlg immunoprecipitates. Direct interaction between hDlg and p56lck is demonstrated using glutathione S-transferase fusion proteins of hDlg and recombinant p56lck expressed in the baculovirus-infected Sf9 cells. The p56lck binding site was localized within the amino-terminal segment of hDlg containing proline-rich domain. In addition, we show in vivo association of hDlg with Kv1.3 channel, which was expressed in T lymphocytes as an epitope-tagged protein using a vaccinia virus expression system. Taken together, these results provide the first evidence of a direct interaction between hDlg and p56lck tyrosine kinase and suggest a novel function of hDlg in coupling tyrosine kinase and voltage-gated potassium channel in T lymphocytes.

Identification of two essential phosphorylated threonine residues in the catalytic domain of Mekk1. Indirect activation by Pak3 and protein kinase C

The 78-kDa protein kinase Mekk1 plays an important role in the stress response pathway that involves the activation of downstream kinases Sek1 and stress-activated protein kinase/c-Jun NH2-terminal kinase. Conserved serine and threonine residues located between the kinase subdomains VII and VIII of many protein kinases are phosphorylated for maximal kinase activation. Two threonine residues within this region in Mekk1 at positions 560 and 572, but not the serine at 557, were shown to be essential for catalytic activity in this study. When these threonine residues were replaced with alanine, there was a significant loss in phosphotransferase activity toward the primary substrate, Sek1, and a large decrease in autophosphorylation activity. Site-directed mutagenesis demonstrated that these threonine residues cannot be replaced with either serine or glutamic acid for preservation of phosphotransferase activity. Further examination of the Mekk1 mutants isolated from 32P-labeled transfected COS cells showed that Thr-560 and Thr-572 were indeed phosphorylated after two-dimensional tryptic-chymotryptic phosphopeptide analysis. Additional determinants in the NH2-terminal domain of Mekk1 also play a role in the regulation of Mekk1 activity. Although Pak3 and PKC can activate Mekk1 in vivo, this interaction is indirect and independent, since there was no direct phosphorylation of Mekk1 by Pak3 or PKC or of Pak3 by PKC, respectively.

Erythrocyte membrane alterations in Plasmodium falciparum malaria sequestration

Plasmodium falciparum malaria, the most lethal form of human malaria, claims at least 2 million lives worldwide each year. Recently, there has been a significant advance in our understanding of the molecular basis of P. falciparum sequestration, a distinctive pathologic feature that often leads to fatal human cerebral malaria. Parasite-derived VAR proteins (Plasmodium falciparum-infected erythrocyte membrane protein 1) have been cloned and identified as antigenically diverse cytoadherent receptors localized to the knob protrusions that act as attachment points in parasite sequestration. Evidence now supports the hypothesis that cryptic regions of band 3 protein are parasite-induced, host-derived erythrocyte receptors mediating parasite sequestration. Knob structures have been localized to spectrin-actin-protein 4.1 junctions in intact spread membrane skeletons. A recombinant domain of knob-associated histidine-rich protein, a major protein found in both membrane-intact and isolated knobs, has been shown to associate with filamentous actin and spectrin. Parasite- and host-derived erythrocyte membrane proteins involved in P. falciparum sequestration are discussed in this review.

Effects of somatostatin and somatotropin on the in vitro testicular steroidogenesis in hamster

Adult hamsters were exposed to short-photoperiod, and injected with either somatotropin (GH), somatostatin (GHRIH), or saline for eight weeks. Hamster testis fragments of similar size were incubated with or without hCG. No significant differences in the basal media testosterone and estradiol levels were observed among groups. Treatment with GH potentiated the hCG-dependent increase in media testosterone. Contrary to what was expected, treatment with GHRIH did not only not reduce the hCG-related elevation in media testosterone, but even produced a numerical increase of it. Treatment with GHRIH potentiated the hCG-dependent increase in media estradiol, whereas treatment with GH produced only a numerical increase of the response. Furthermore, the combined exposure to GHRIH and hCG appeared to cause an increase in the efficiency of testicular aromatase. Since previous data indicated that the combined deficiency of lactotropic and somatotropic actions severely impairs testicular steroidogenesis, treatment with GHRIH should have caused further steroidogenic impairment in hamsters exposed to short-photoperiod. Since this does not appear to be the case, it could be postulated that GHRIH has a direct stimulatory or at least a protective effect on testicular steroidogenesis.

Early treatment of obese (ob/ob) mice with triiodothyronine increases oxidative metabolism in muscle but not in brown adipose tissue or liver

We explored the possibility that early replacement of low triiodothyronine (T3) may improve the low oxidative metabolism in metabolically important tissues of ob/ob mice. Triiodothyronine doses (2.5 to 25.0 micrograms/100 g body wt) were injected intraperitoneally into ob/ob and non-ob/ob mice daily from 3 wk until 6 wk of age. Untreated ob/ob and non-ob/ob mice were injected with saline (pH 9.1). Food intake was equalized across all groups. At 6 wk of age, the O2 consumption of muscle, white and brown adipose tissues, and hepatocytes was measured. The saline-treated ob/ob mice showed lower muscle weights, higher fat pad and liver weights, and larger fat cell sizes than saline-treated non-ob/ob mice. In ob/ob mice, tissue O2 consumption was the same in muscle, lower in brown and white adipose tissues, but higher in liver compared with values in non-ob/ob mice. Triiodothyronine treatment in ob/ob mice resulted in lower values for body weight, liver weight, hepatocyte number, liver protein, epididymal fat pad weight, and white adipocyte number and size than in saline-treated ob/ob mice. Triiodothyronine treatment increased soleus muscle, liver and brown adipose tissue O2 consumption in non-ob/ob mice. In ob/ob mice, triiodothyronine increased only soleus muscle O2 consumption and required higher doses than in non-ob/ob mice to achieve an effect. These data are consistent with the concept of tissue triiodothyronine resistance in ob/ob mice. Low triiodothyronine levels and tissue resistance to triiodothyronine might be important early defects in this obesity syndrome.

Early treatment of obese (ob/ob) mice with triiodothyronine increases oxygen consumption and temperature and decreases body fat content

An early abnormality in the ob/ob mouse is a low circulating level of the thyroid hormone, triiodothyronine (T3). The possibility was explored that early T3 treatment of ob/ob mice will increase oxidative metabolism and lower body fat content. Doses of T3, ranging from 0.0 to 25.0 micrograms/100 g body wt were injected, ip, into ob/ob and non-ob/ob mice daily from 3 weeks until 6 weeks of age. Food intake was equalized across all groups to that consumed by non-ob/ob saline-treated group. At 6 weeks of age, body weight, serum concentrations of thyroxine (T4), T3, insulin and glucose, oxygen consumption, colonic temperature, and body composition were analyzed. T3 treatment decreased body weight, increased body oxygen consumption, increased colonic temperature, and decreased body fat without a significant change in body protein in ob/ob mice. T3 treatment also increased serum T3, and decreased serum T4, insulin, and glucose concentrations in ob/ob mice. Because total body protein did not change as a result of T3 treatment, the increased oxidative metabolism due to T3 treatment was probably via the change of metabolic activity of the total lean body mass or the specific metabolically active tissues in the ob/ob mice, such as brown adipose tissue, liver, or muscle.

Mechanism of human placental aromatase: a new active site model

Based on Akhtar's ferric peroxide mechanism and on recent studies in our own laboratory, we present a detailed proposal for aromatase action. This picture can account for the known stereochemical consequences at C-19 observed by others using isotopes of hydrogen and oxygen. The postulated process involves anchoring of the 19-hydroxymethyl and 19-oxo groups at the active site by a glutamate residue, which also serves to activate the 19-oxo group for attack by ferric peroxy species in the third oxidative step.

Oxygen consumption of muscles from ob/ob and Ay/a strains of obese mice

Oxygen consumption was measured in the in vitro preparations of soleus, extensor digitorum longus, gracilis, and diaphragm muscles from young ob/ob obese mice. In young Ay/a obese mice, similar measurements were made with in vitro preparations of soleus, gracilis, and diaphragm muscles. These young obese mice were heavier than their nonobese littermates. Muscle weights were similar in obese and nonobese mice. In the Ay/a obese mice, values of muscle oxygen consumption were similar to those found in the a/a nonobese littermates. This correlates well with other known information about the Ay/a variety of obesity. In the ob/ob obese mice, values of oxygen consumption in the gracilis and diaphragm muscle preparations were lower than those in nonobese littermates. These data indicate that some muscles in the ob/ob obese mice contribute to the depressed whole animal oxygen consumption by virtue of defective oxidative metabolism. The data also indicate that the tissue defects are very different in various types of obese animal models. This probably is also true for different types of human obesity.

Effect of triiodothyronine on glucose utilization in diaphragm of obese (ob/ob) mice

Genetically obese-hyperglycemic (ob/ob) mice are hypothyroid, hyperinsulinemic, and insulin resistant. Because muscle plays an important role in glucose homeostasis, the role of triiodothyronine (T3) in regulation of insulin-sensitive glucose utilization by muscles of obese mice was examined. Four doses of T3, 5.0, 12.5, 25.0, and 50.0 micrograms/100 g body weight were injected, i.p., into obese and nonobese mice daily from 3 weeks until 6 weeks of age. Food consumption and body weight were decreased at lower doses of T3 and increased at higher doses of T3 in both obese and nonobese mice. By 6 weeks of age all doses of T3 treatment increased oxygen consumption in both genotypes. At 6 weeks of age, the diaphragms from the saline-injected nonobese mice had greater in-vitro insulin-stimulated glucose utilization than muscles from the saline-injected obese mice. Both anaerobic and aerobic glucose oxidation were increased by T3 treatment, but the obese had greater increases than those observed in muscles from nonobese mice. Muscles from obese mice increased insulin-stimulated glucose utilization by T3 treatment to that of the nonobese level, whereas there was no change in insulin-stimulated glucose utilization of nonobese mice. Muscle glycogen synthesis in obese and nonobese mice was decreased with very high T3 doses. A higher dose of T3 was required to increase glucose utilization in the obese muscles than in the nonobese muscles. The results suggest that a functional hypothyroidism or T3 resistance may be an early part of this particular obesity syndrome.