2020 ASCO, 2023 NCCN, 2023 MASCC/ESMO, and 2019 CCO: a comparison of antiemetic guidelines for the treatment of chemotherapy-induced nausea and vomiting in cancer patients

Chemotherapy-induced nausea and vomiting (CINV) is a common toxicity that may impair the quality of life of patients with various malignancies ranging from early to end stages. In light of frequent changes to the guidelines for optimal management of CINV, we undertook this narrative review to compare the most recent guidelines published by ASCO (2020), NCCN (2023), MASCC/ESMO (2023), and CCO (2019). The processes undertaken by each organization to evaluate existing literature were also described. Although ASCO, NCCN, MASCC/ESMO, and CCO guidelines for the treatment and prevention of CINV share many fundamental similarities, the literature surrounding low and minimal emetic risk regimens is lacking. Current data regarding adherence to these guidelines is poor and warrants further investigation to improve care.

Stereotactic Cardiac Ablative Radiotherapy (SCAR) for Refractory Ventricular Tachycardia: Western Australia Experience

PURPOSE/OBJECTIVE(S)

Ventricular tachycardia is a potentially life-threatening cardiac condition that is associated with significant morbidity and mortality. Despite advances in medical therapies, implantable cardioverter-defibrillator (ICD) and catheter ablative therapy (CAT), some patients continue to suffer recurrent VT. SCAR is a highly accurate, non-invasive, and novel ablative therapeutic option that has shown promising results in the treatment of refractory VT patients associated with structural heart disease. Early case series and subsequent prospective clinical trials have demonstrated SCAR to be well-tolerated with acceptable safety profiles and consistently decreased VT episodes in VT patients, who failed all conventional antiarrhythmic medications and CAT. The aim of the current study is to report the efficacy and safety/tolerability of SCAR in ICD-dependent patients with refractory VT in Western Australia, Australia.

MATERIALS/METHODS

Seven patients with recurrent refractory VT, deemed high risk or non-suitable for CAT, were referred to GenesisCare at Fiona Stanley Hospital, Western Australia for SCAR between July 2020 and November 2022. Target volume definition and delineation involved interdisciplinary teams by combining all available clinical, electrophysiological mapping and diagnostic/planning cardiac imaging data to generate radiotherapy plans. Patients were treated whilst awake, with a single dose of 25 Gy using VMAT technique on the Synergy Linac with stereotactic X-ray tool capability. Efficacy was assessed by counting the number of episodes of VT and ICD shocks after SCAR. Safety and tolerability were evaluated by treatment related toxicities during follow up.

RESULTS

Of the seven patients referred for SCAR, only five received SCAR as two patients died from their refractory VT before their radiotherapy. For the patients receiving SCAR with at least 6 months follow-up, overall reduction in VT episodes and ICD shocks was 95% and 85%, respectively. No significant treatment-related toxicities were documented during follow-up. Two patients had died. Neither of their deaths were directly attributed to their radiotherapy. One patient died after requesting to cease her antiarrhythmic medications and to have her ICD switched off 2 days after SCAR (against medical advice). The other patient died 431 days after SCAR from aspiration pneumonia after fracturing her cervical spine following a fall at home and was unrelated to her VT.

CONCLUSION

Our data reflects international experience in terms of treatment efficacy and safety profiles of SCAR for patients with refractory VT. SCAR is increasingly recognized as an alternative cardiac ablative option for ICD-dependent VT patients who failed all conventional antiarrhythmic treatments. Nonetheless, careful patient selection and longer-term follow-up are required to ensure the optimal treatment outcomes can be achieved in these patients.

Societal cost of childhood intellectual disability in Australia

BACKGROUND

There is limited research quantifying the direct and indirect economic costs associated with intellectual disability (ID) in Australia. Costs incurred by families, governments and broader society include time spent providing care, absenteeism and increased healthcare utilisation. The purpose of this research is to quantify the costs associated with ID in childhood using a range of methods to collect cost data.

METHODS

Costs included healthcare service utilisation, pharmaceutical use, caregiver productivity losses and time spent providing care because of the child's disability. The sample comprised caregivers with a child with ID aged between 2 and 10 years old recruited in Australia. Healthcare service utilisation and pharmaceutical use were obtained from routinely collected administrative claims data. Healthcare utilisation not captured in the routinely collected administrative data and absenteeism data were obtained from a retrospective recall-based questionnaire. Time spent providing care because of the child's disability was obtained using a time-use diary.

RESULTS

The total cost of ID in Australia was estimated to be AUD 72 027 per year per child, and the total cost of ID in childhood was estimated to be AUD 12.5 billion per year. The cost to governments of ID in childhood was estimated to be AUD 6385 per child per year, resulting in a total cost to government of AUD 1.1 billion per year.

CONCLUSIONS

This is the first study to estimate the direct and indirect costs associated with ID in childhood. The results of this research demonstrate the considerable economic impact of ID in childhood on families, governments and broader society in terms of both direct and indirect costs. An understanding of the cost implications of any intervention are critical in assisting policymakers in planning and prioritising of health services.

Health-related quality of life amongst primary caregivers of children with intellectual disability

BACKGROUND

Children with intellectual disability (ID) frequently have significant educational, social and health care needs, resulting in caregivers often experiencing a wide range of negative effects. This paper aims to determine the impact of childhood ID on caregivers' health-related quality of life (HRQoL) across co-morbid diagnostic groups. The second aim of this study is to determine the risk factors associated with lower HRQoL in this population.

METHODS

Caregivers of a child with ID aged between 2 and 12 years old completed an online survey to determine their HRQoL using the EQ-5D-5L measure. They were also asked demographic questions and about their dependent child's level of behavioural and emotional difficulties.

RESULTS

Of the total sample of 634 caregivers, 604 caregivers completed all five questions of the EQ-5D-5L. The mean age of caregivers was 39.1 years and 91% were women. Caregivers spent on average 66.6 h per week caring for their child related to their child's disability. The mean EQ-5D-5L score of caregivers was 0.80 (95% confidence interval: 0.79, 0.82), which is below the estimated Australian population norms (mean utility score of 0.92) for the age-equivalent population. Caregivers of children with autism spectrum disorders reported the lowest HRQoL (0.77, 95% confidence interval: 0.74, 0.79) of the five included co-morbid diagnostic groups. Caregivers with a lower income, a perceived low level of social support and children with higher degree of behavioural and emotional problems were likely to have a statistically lower HRQoL.

CONCLUSIONS

This is the first study to produce utility values for caregivers of children with ID. The utility values can be used to compare health states and can be used to inform comparative cost-effectiveness analyses. Demonstrating that caregivers of children with ID have reduced HRQoL and that this is associated with the degree of behavioural and emotional problems has important policy implications, highlighting the potential for policy interventions that target behavioural and emotional problems to improve outcomes for caregivers.

Framing of the opioid problem in cancer pain management in Canada

Two guidelines about opioid use in chronic pain management were published in 2017: the Canadian Guideline for Opioids for Chronic Non-Cancer Pain and the European Pain Federation position paper on appropriate opioid use in chronic pain management. Though the target populations for the guidelines are the same, their recommendations differ depending on their purpose. The intent of the Canadian guideline is to reduce the incidence of serious adverse effects. Its goal was therefore to set limits on the use of opioids. In contrast, the European Pain Federation position paper is meant to promote safe and appropriate opioid use for chronic pain. The content of the two guidelines could have unintentional consequences on other populations that receive opioid therapy for symptom management, such as patients with cancer. In this article, we present expert opinion about those chronic pain management guidelines and their impact on patients with cancer diagnoses, especially those with histories of substance use disorder and psychiatric conditions. Though some principles of chronic pain management can be extrapolated, we recommend that guidelines for cancer pain management should be developed using empirical data primarily from patients with cancer who are receiving opioid therapy.

Neuromuscular changes and the rapid adaptation following a bout of damaging eccentric exercise

INTRODUCTION

An initial bout of eccentric exercise is known to protect against muscle damage following a repeated bout of the same exercise; however, the neuromuscular adaptations owing to this phenomenon are unknown.

AIM

To determine whether neuromuscular disturbances are modulated following a repeated bout of eccentric exercise.

METHODS

Following eccentric exercise performed with the elbow flexors, we measured maximal voluntary force, resting twitch force, muscle soreness, creatine kinase (CK) and voluntary activation (VA) using motor point and motor cortex stimulation at baseline, immediately post-exercise and at 1, 2, 3, 4 and 7 days post-exercise on two occasions, separated by 3 weeks.

RESULTS

Significant muscle damage and fatigue were evident following the first exercise bout; maximal voluntary contraction (MVC) was reduced immediately by 35% and remained depressed at 7 days post-exercise. Soreness and CK release peaked at 3 and 4 days post-exercise respectively. Resting twitch force remained significantly reduced at 7 days (-48%), whilst VA measured with motor point and motor cortex stimulation was reduced until 2 and 3 days respectively. A repeated bout effect (RBE) was observed with attenuated soreness and CK release and a quicker recovery of MVC and resting twitch force. A similar decrement in VA was observed following both bouts; however, following the repeated bout there was a significantly smaller reduction in, and a faster recovery of, VA measured using motor cortical stimulation.

CONCLUSION

Our data suggest that the RBE may be explained, partly, by a modification in motor corticospinal drive.

Heavy-resistance exercise-induced increases in jump performance are not explained by changes in neuromuscular function

Post-activation potentiation (PAP) is the increased involuntary muscle twitch response to stimulation following strong contraction. The enhancement to whole-body explosive muscular performance (PE) after heavy-resistance exercise is often attributed to modulations in neuromuscular function that are proposed to reflect PAP, but the evidence to support this is equivocal. We assessed the neuromuscular basis of PE using transcranial magnetic stimulation (TMS) of the primary motor cortex, and electrical stimulation of the femoral nerve. Eleven male athletes performed heavy-resistance exercise with measures of countermovement jump (CMJ) pre- and 8 min post-exercise. Pre-exercise and after the final CMJ, single- and paired-pulse TMS were delivered during submaximal isometric knee-extensor contractions to measure corticospinal excitability, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF), with motor evoked potentials recorded from rectus femoris. Twitch responses to motor nerve stimulation during and post maximum-knee-extensor contractions were studied to quantify voluntary activation (VA) and potentiated twitch (Q_tw,pot ). The experimental protocol successfully induced PE (+4 ± 1% change in CMJ, P = 0.01), but no changes were observed for maximum voluntary force, VA, corticospinal excitability, SICI or ICF (all P > 0.05), and Q_tw,pot declined (P < 0.001). An enhancement of muscular performance after heavy-resistance exercise was not accompanied by PAP, or changes in measures of neuromuscular function.

AltitudeOmics: exercise-induced supraspinal fatigue is attenuated in healthy humans after acclimatization to high altitude

AIMS

We asked whether acclimatization to chronic hypoxia (CH) attenuates the level of supraspinal fatigue that is observed after locomotor exercise in acute hypoxia (AH).

METHODS

Seven recreationally active participants performed identical bouts of constant-load cycling (131 ± 39 W, 10.1 ± 1.4 min) on three occasions: (i) in normoxia (N, PI O2 , 147.1 mmHg); (ii) in AH (FI O2 , 0.105; PI O2 , 73.8 mmHg); and (iii) after 14 days in CH (5260 m; PI O2 , 75.7 mmHg). Throughout trials, prefrontal-cortex tissue oxygenation and middle cerebral artery blood velocity (MCAV) were assessed using near-infrared-spectroscopy and transcranial Doppler sonography. Pre- and post-exercise twitch responses to femoral nerve stimulation and transcranial magnetic stimulation were obtained to assess neuromuscular and corticospinal function.

RESULTS

In AH, prefrontal oxygenation declined at rest (Δ7 ± 5%) and end-exercise (Δ26 ± 13%) (P < 0.01); the degree of deoxygenation in AH was greater than N and CH (P < 0.05). The cerebral O2 delivery index (MCAV × Ca O2 ) was 19 ± 14% lower during the final minute of exercise in AH compared to N (P = 0.013) and 20 ± 12% lower compared to CH (P = 0.040). Maximum voluntary and potentiated twitch force were decreased below baseline after exercise in AH and CH, but not N. Cortical voluntary activation decreased below baseline after exercise in AH (Δ11%, P = 0.014), but not CH (Δ6%, P = 0.174) or N (Δ4%, P = 0.298). A twofold greater increase in motor-evoked potential amplitude was evident after exercise in CH compared to AH and N.

CONCLUSION

These data indicate that exacerbated supraspinal fatigue after exercise in AH is attenuated after 14 days of acclimatization to altitude. The reduced development of supraspinal fatigue in CH may have been attributable to increased corticospinal excitability, consequent to an increased cerebral O2 delivery.

Corticospinal responses of resistance-trained and un-trained males during dynamic muscle contractions

Little is known regarding the modulation and the plasticity of the neural pathway interconnecting elements of the central nervous system and skeletal muscle in resistant-trained individuals. The aim of the study was to compare corticospinal and spinal responses measured during dynamic muscle contractions of the tibialis anterior in resistance trained (RT) and un-trained (UT) males. Nine UT and 10 RT male volunteers reported to the laboratory 24h following a familiarisation session. Motor evoked potentials (MEPs) and the cortical silent period were evoked using transcranial magnetic stimulation at a range of contraction intensities and was delivered as the ankle passed 90° during shortening and lengthening contractions. The Hoffmann reflex (H-reflex) and V-waves were evoked with peripheral nerve stimulation. Despite the RT group being significantly stronger during shortening (28%; P=0.023: CI=1.27-15.1Nm), lengthening (25%; P=0.041: CI=0.27-17.0Nm) and isometric muscle actions (20%; P=0.041; CI=0.77-14.9Nm), no differences between the groups existed for corticospinal or spinal variables. Lack of detectable differences between RT and UT individuals may be linked to minimal exposure to task specific, isolated high intensity resistance training of the TA muscle.

Recovery time of motor evoked potentials following lengthening and shortening muscle action in the tibialis anterior

Motor evoked potentials (MEP) at rest remain facilitated following an isometric muscle contraction. Because the pre-synaptic and post-synaptic control of shortening (SHO) and lengthening (LEN) contractions differs, the possibility exists that the recovery of the MEP is also task specific. The time course of MEP recovery was assessed in the tibialis anterior following SHO and LEN (0.26 rad/s) at 25% and 80% of maximal voluntary contraction. Following LEN and SHO contractions, the MEP recovered to baseline levels within 10s. Despite task-specific differences between SHO and LEN contractions, the MEP facilitation from the augmented neurotransmitter release appears to be short lasting and not influenced by contraction type.

Severe zoledronic acid (ZOL)-associated hypophosphatemia and prognosis in patients with castration-resistant prostate cancer (CRPC)

e15180

Background: ZOL therapy is associated with severe (i.e., grade ≥ 3) hypocalcemia and hypophosphatemia in a subset of patients with metastatic CRPC. However, as opposed to the distinct clinical picture of hypocalcemia, the symptoms of hypophosphatemia are less pathognomonic. Furthermore, serum phosphate abnormalities are not regularly reported. Methods: To characterize the rate and clinical impact of severe hypophosphatemia in CRPC patients undergoing ZOL therapy, we identified CRPC patients receiving at least 3 doses of ZOL at our Centre between 01/2004 and 03/2011. Patient demographics, disease characteristics and laboratory parameters were extracted using the Oncology Symptom Control and Information Resource database, and by means of manual chart review. Results: 12 of 90 evaluable patients developed grade ≥ 3 hypophosphatemia (nadir) after 364±299 days (mean±SD) following the first dose of ZOL. While only one patient presented with concomitant severe hypocalcemia, the hypophosphatemia nadir coincided with rising PSA readings in 9 out of 11 informative patients. Severe ZOL-associated hypophosphatemia identified patients with worse outcome (median overall survival from time of CRPC diagnosis to death 685 days) compared to patients without documented hypophosphatemia (907 days, HR 0.52, p=0.049; n=42), or patients with grade 1-2 hypophosphatemia (1035 days, HR 0.44, p=0.016; n=36). Otherwise, the prognostic nomogram developed by Armstrong et al appears not to capture the poor prognosis of patients with severe ZOL-associated hypophosphatemia. Conclusions: Grade 3-4 hypophosphatemia occurs in about 15% of CRPC patients undergoing ZOL therapy and is associated with worse prognosis when compared to patients with absent or mild hypophosphatemia. The latter is usually transient and likely related to increased parathyroid hormone levels due to calcium decreases as a consequence of bisphosphonate therapy. On the other hand, the distinct clinical behavior of CRPC presenting with ZOL-associated severe hypophosphatemia suggests that secreted tumor-associated factors such as fibroblast growth factor 23 may contribute to this phenomenon.

Use of zoledronic acid therapy–associated severe hypophosphatemia to identify poor-prognosis patients with metastatic castration-resistant prostate cancer

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Background: Zoledronic acid (ZOL) therapy is associated with severe (i.e., grade 3/4 according to CTCAEv4.0) hypocalcemia and hypophosphatemia in a subset of patients with metastatic castration-resistant prostate cancer (mCRPC) to bone. However, as opposed to the distinct clinical picture of hypocalcemia, the symptoms of hypophosphatemia are less pathognomonic. Furthermore, the rate of hypophosphatemia is not regularly reported.

Methods: To characterize the rate and circumstances of severe hypophosphatemia in mCRPC patients undergoing ZOL therapy, we identified mCRPC patients receiving at least 3 doses of ZOL therapy at our Centre between 2004 and 03/2011. Patient demographics, disease and laboratory parameters were extracted by using the Oncology Symptom Control and Information Resource database, and by means of manual chart review.

Results: 11 of 112 patients (10%) developed grade 3/4 hypophosphatemia (nadir) after 241±223 days (mean±SD) following the first dose of ZOL. Only one patient presented with concomitant severe hypocalcemia. Interestingly, the hypophosphatemia nadir coincided with rising PSA readings in 9 out of 10 informative patients. Furthermore, ZOL-associated severe hypophosphatemia identified mCRPC patients with worse outcome (time from CRPC diagnosis to death 628±317 days, versus 901±526 days in CRPC patients without severe ZOL-associated hypophosphatemia, p < 0.028).

Conclusions: 10% of mCRPC patients undergoing ZOL therapy presented with grade 3/4 hypophosphatemia. While hypocalcemia usually occurs within the first 6 months of ZOL therapy, ZOL-associated severe hypophosphatemia is a relatively late event. It appears to occur at the time of disease progression and is associated with a poor outcome.

Enhanced invasive properties exhibited by smooth muscle cells are associated with elevated production of MMP-2 in patients with aortic aneurysms

BACKGROUND

abdominal aortic aneurysms (AAA) are associated with excessive vascular matrix remodelling. Recent findings suggest a systemic overproduction of matrix metalloproteinases-2 (MMP-2) by vascular smooth muscle cells (SMC) may be pivotal aetiologically. SMC migration is facilitated by MMP mediated proteolysis of the basement membrane and extracellular matrix. Our aim was to see if enhanced MMP-2 production by these SMC exhibit increased invasion, in an in vitro model of migration.

METHOD

SMC were derived from inferior mesenteric vein (IMV) harvested from patients undergoing aneurysm repair (n=6) or colectomy for diverticulosis (n=6, control). Using a modified Boyden chamber chemotaxis was measured towards platelet derived growth factor (PDGF) and foetal calf serum (FCS) and invasion through a Matrigel layer. MMP-2 production was quantified by ELISA and gelatin zymography.

RESULTS

chemoattractant studies demonstrated no difference in the effect of PDGF or FCS between the two populations of SMC. However, invasive studies demonstrated a significant increase in the number of migrating SMC isolated from IMV of AAA patients. Analysis of culture media extracts revealed that this difference was associated with a significant increase in production of MMP-2.

CONCLUSION

SMC derived from patients with AAA demonstrate increased invasive properties when compared to a control group. Increased migration appears to be due to overproduction of MMP-2. The enhanced migratory potential of these SMC may lead to extracellular matrix remodelling and subsequent medial disruption demonstrated in the aneurysmal aorta. These data further support evidence of the proteolytic role of MMP-2 in cell migration.

Risk factor assessment for patients with peripheral arterial disease

Peripheral arterial disease is a chronic condition that affects a significant proportion of the adult population. Treatment is often prolonged and may be painful, with a slow rate of healing. However, current evidence to support risk-factor assessment highlights the role of the nurse in encouraging lifestyle modification, leading to an improvement in the patient's quality of life.

Ubiquitous elevation of matrix metalloproteinase-2 expression in the vasculature of patients with abdominal aneurysms

BACKGROUND

Patients with abdominal aortic aneurysms (AAAs) exhibit arterial dilation and altered matrix composition throughout the vasculature. Matrix metalloproteinase-2 (MMP-2) is the dominant elastase in small AAAs, and overexpression of MMP-2 in vascular smooth muscle cells (SMCs) may be a primary etiological event in aneurysm genesis. The aim of this study was to investigate MMP-2 production in vascular tissue remote from the abdominal aorta.

METHODS AND RESULTS

Inferior mesenteric vein (IMV) was harvested from patients undergoing aneurysm repair (n=21) or colectomy for diverticular disease (n=13, control). Matrix composition of the vessels was determined by stereological techniques. MMPs were extracted from tissue homogenates and quantified by gelatin zymography and ELISA. MMP-2, membrane type-1 MMP (MT1-MMP), and tissue inhibitor of metalloproteinases type 2 (TIMP-2) expression were determined by Northern analysis. SMCs were isolated from IMV, and the production and expression of MMP-2 and TIMP-2 in the SMC lines were quantified. Tissue homogenates and isolated inferior mesenteric SMCs from patients with aneurysms demonstrated significantly elevated MMP-2 levels, with no difference in TIMP-2 or MT1-MMP. These differences were a result of increased MMP-2 expression. Histological examination revealed fragmentation of elastin fibers within venous tissue obtained from patients with AAA and a significant depletion of the elastin within the media. In situ zymography localized elastolysis to medial SMCs.

CONCLUSIONS

Patients with AAA have elevated MMP-2 levels in the vasculature remote from the aorta. This finding is due to increased MMP-2 expression from SMCs, a characteristic maintained in tissue culture. These data support both the systemic nature of aneurysmal disease and a primary role of MMP-2 in aneurysm formation.

The ex vivo wettability of soft contact lenses

PURPOSE

To investigate the ex vivo wettability of Etafilcon A contact lenses over an eight hour period of wear and observe the influence of surfactant pre-treatment.

METHODS

Etafilcon A hydrogel lenses, comprising poly[2-hydroxyethyl methacrylate-co-methacrylic acid] and 58% water, were soaked for 12 hours in either 0.9% saline (control) or a 1% aqueous solution of poloxamine 1107 (treated). The advancing and receding contact angles were subsequently determined ex vivo after various periods of wear in six adapted contact lens wearers using a single-blind, randomised protocol. Contact angles were measured with a dynamic contact angle tensiometer, using the Wilhelmy plate technique. Patient comfort scores were recorded and the static surface tensions of the probe fluids assessed.

RESULTS

Control lenses exhibited no change in wetting angles over time, indicating a lack of surface modification by components within the tear film. Treated lenses exhibited a significantly reduced advancing angle (p < 0.001) and hysteresis angle (p < 0.001) when compared with control lenses. In addition, treated lenses were consistently rated as being more comfortable than control lenses (p = 0.04).

CONCLUSIONS

This study has shown clearly that new Etafilcon A lenses do not exhibit significant changes in wettability during the initial four hour wearing period. Pre-treatment of such lenses with a polymeric surfactant results in wetting of the lenses due to the adsorption of surfactant. The surfactant is retained by the lens for at least eight hours of wear, resulting in significant improvements in subjective comfort, especially over the first 30 minutes of wear.

Cortical map asymmetries in the context of transcallosal excitatory influences

There is long-standing disagreement among experimentalists about whether transcallosal interhemispheric influences are primarily excitatory or inhibitory. Past computational models exploring this issue have encountered a similar dilemma: inhibitory callosal influences best explain hemispheric functional asymmetries, but excitatory callosal influences best explain transcallosal diaschisis. We recently hypothesized that this dilemma might be resolved by assuming excitatory callosal influences and a subcortical mechanism for cross-midline inhibition. Here we explore the feasibility of this hypothesis by examining a model of map formation in corresponding left and right cortical regions. The results show for the first time that both map asymmetries and diaschisis-like changes can be produced in a single model, suggesting that subcortical inhibitory processes may contribute more to asymmetric cortical functionality than is generally recognized.

Endovascular AAA repair attenuates the inflammatory and renal responses associated with conventional surgery

PURPOSE

To quantify the inflammatory and renal parameters in comparative cohorts of patients undergoing surgical or endovascular repair of abdominal aortic aneurysms (AAAs).

METHODS

Forty-three patients (41 men; ages 58-81 years) underwent endovascular or conventional aneurysm surgery according to aortic morphology. All patients received a standard general anesthetic and had 12 serial blood and urine samples collected during the perioperative period. Samples underwent analysis for the cytokines interleukin (IL) 1beta tumor necrosis factor-alpha (TNF-alpha), and IL-6. White cell and platelet activation were estimated indirectly by measuring sL-selectin and 11-dehydrothromboxane B2, respectively. The urinary albumin:creatinine ratio (ACR) and N-acetyl-beta-D-glucosaminidase (NAG) activity were estimated to assess renal injury. Fibrinogen and fibrinogen degradation products were calculated to assess activation of the clotting cascade.

RESULTS

Twenty-three patients underwent endovascular AAA repair and 20 had conventional surgery. Concentrations of IL-6 (p < 0.002) and TNF-alpha (p < 0.0004) were significantly higher in the conventional group. The ACR (p < 0.002) and urinary NAGs (p < 0.0009) were also significantly higher in this group, suggesting greater renal injury. Platelet activity was significantly greater in the endovascular group (p < 0.01), perhaps indicating thrombus organization within the aneurysm sac.

CONCLUSIONS

These data suggest that the inflammatory response associated with conventional aneurysm repair is largely obviated by endovascular techniques. This may potentially translate to a lower incidence of multiple organ failure after endovascular surgery.

Localization of matrix metalloproteinase 2 within the aneurysmal and normal aortic wall

BACKGROUND

Current research has shed new light on the role of matrix metalloproteinase (MMP) 2 in the development of abdominal aortic aneurysms (AAAs). MMP-2 is a major protease in the wall of small aneurysms and is produced at increased levels by smooth muscle cells derived from AAAs compared with normal controls. In vivo, MMP-2 is produced as an inactive proenzyme that is activated predominantly by the cell membrane-bound enzyme, membrane type 1 matrix metalloproteinase (MT1-MMP). This study investigated the production of the MMP-2-MT1-MMP-tissue inhibitor of metalloproteinases (TIMP) 2 system within the wall of aortic aneurysms and in age-matched control arterial tissue.

METHODS

Arterial tissue from four patients with aortic aneurysms and four age-matched aortic samples was examined for the production and expression of MMP-2, TIMP-2 and MT1-MMP protein using immunohistochemistry, in situ hybridization and in situ zymography.

RESULTS

All components of the MMP-2-TIMP-2-MT1-MMP enzyme system were detected in the arterial wall of both aneurysm and control samples, specifically in the medial tissue. The enzymes co-localized with medial smooth muscle cells. Gelatinolytic activity was localized to elastin fibres in normal and aneurysmal aorta.

CONCLUSION

The presence of MT1-MMP within the media of arterial tissue suggests a powerful pathway for the activation of MMP-2. The localization of the MMP-2-TIMP-2-MT1-MMP enzyme system to the medial layer of the arterial wall gives support to the concept that this system may play an aetiological role in the pathogenesis of AAAs.

Increased matrix metalloproteinase 2 expression in vascular smooth muscle cells cultured from abdominal aortic aneurysms

OBJECTIVES

Recent evidence has implicated matrix metalloproteinase 2 (MMP-2) in the pathogenesis of aneurysms. The aim of this study was to examine MMP-2 production and expression by aortic smooth muscle cells (SMCs) and dermal fibroblasts derived from patients with abdominal aortic aneurysms (AAAs).

METHODS

Aortic SMCs and dermal fibroblasts were cultured from patients with AAAs or from age-matched controls with atherosclerosis. The production of MMP and tissue inhibitor of metalloproteinase into culture media was analyzed with the use of gelatin zymography, Western blotting, and enzyme-linked immunosorbent assay. Gene expression was analyzed with Northern blotting.

RESULTS

All cells studied constitutively produced MMP-2. Aortic SMCs cultured from aneurysmal tissue expressed MMP-2 protein and messenger RNA at a significantly higher level than SMCs from controls (P =.008). Dermal fibroblasts from patients with AAAs expressed MMP-2 at a similar level to controls. In both cell types, tissue inhibitor of metalloproteinase 2 and membrane type 1-MMP were expressed at similar levels.

CONCLUSIONS

These data suggested that the regulation of MMP-2 gene expression was altered in the aortic SMCs of patients with aneurysms, but this finding was not repeated in other mesenchymal tissue.

Peripheral vascular disease

This article discusses peripheral vascular disease and its associated risk factors. It outlines clinical patient assessment, medical interventions and the role of the nurse in secondary prevention.

Increased matrix metalloproteinase-9 activity in unstable carotid plaques. A potential role in acute plaque disruption

BACKGROUND AND PURPOSE

Acute disruption of atherosclerotic plaques precedes the onset of clinical syndromes, and studies have implicated a role for matrix metalloproteinases (MMPs) in this process. The aim of this study was to establish the character, level, and expression of MMPs in carotid plaques and to correlate this with clinical status, cerebral embolization, and histology.

METHODS

Plaques were obtained from 75 consecutive patients undergoing carotid endarterectomy and divided into 4 groups according to symptomatology (group 1, asymptomatic; group 2, symptomatic >6 months before surgery; group 3, symptomatic within 1 to 6 months; group 4, symptomatic within 1 month). All patients underwent preoperative and intraoperative transcranial Doppler monitoring. Plaques were subjected to histological examination and quantification of MMPs by zymography and ELISA.

RESULTS

The level of MMP-9 was significantly higher in group 4 (median 125.7 ng/mL for group 4, median <32 ng/mL for all other groups; P=0.003), with no difference in the levels of MMPs 1, 2, or 3. Furthermore, the MMP-9 concentration was significantly higher in plaques undergoing spontaneous embolization (P=0.019) and those with histological evidence of plaque instability (P<0.03). In situ hybridization demonstrated increased MMP-9 expression in highly symptomatic plaques in areas of intense inflammatory infiltrate.

CONCLUSIONS

The concentration, production, and expression of MMP-9 is significantly higher in unstable carotid plaques. If this proves to be a causal relationship, MMP-9 may be a strong candidate for pharmacotherapy aimed at stabilizing plaques and preventing stroke.

Marimastat inhibits elastin degradation and matrix metalloproteinase 2 activity in a model of aneurysm disease

BACKGROUND

Abdominal aortic aneurysms are characterized by degradation of the extracellular matrix, with a reduction in the elastin concentration of the arterial media. These changes have been linked to increased levels of endogenous metalloproteinases (MMPs) within the aorta, particularly MMP-2 and MMP-9. This provides a potential therapeutic target for pharmacological agents aimed at reducing the growth rate of small aneurysms. In this study, the ability of marimastat (an MMP inhibitor) to reduce matrix degradation was assessed in a previously described model of aneurysm disease.

METHODS

Porcine aortic segments (n = 12) were preincubated in exogenous pancreatic elastase for 24 h before culture in standard conditions for 13 days with marimastat 10(-5), 10(-6) and 10(-7) mol/l. Control segments were cultured both without marimastat and without elastase. At the termination of culture, MMPs were extracted from the tissue and quantified by substrate gel enzymography. The volume fractions of elastin and collagen were determined by stereological analysis of sections stained with Miller's elastin and van Gieson's stain.

RESULTS

Stereological analysis demonstrated preservation of elastin in aorta treated with marimastat at 10(-6) and 10(-5) mol/l; this was significant at the latter concentration (P = 0.007). This was accompanied by a significant reduction in active MMP-2 activity in the samples treated with marimastat 10(-5) mol/l (P < 0.01).

CONCLUSION

Marimastat significantly inhibited elastin degradation and active MMP-2 production within aortic organ cultures.

Pathogenic mechanisms in ischemic damage: a computational study

The pathogenesis of penumbral tissue infarction during acute ischemic stroke is controversial. This peri-infarct tissue may subsequently die, or survive and recuperate, and its preservation has been a prime goal of recent therapeutic trials in acute stroke. Two major hypotheses currently under consideration are that penumbral tissue is recruited into an infarct by cortical spreading depression (CSD) waves, or by a non-wave self-propagating process such as glutamate excitotoxicity (GE). Careful experimental attempts to discriminate between these two hypotheses have so far been quite ambiguous. Using a computational metabolic model of acute focal stroke we show here that the spatial patterns of tissue damage arising from artificially induced foci of infarction having specific geometric shapes are inherently different. This is due to the distinct propagation characteristics underlying self-regenerating waves and non-wave diffusional processes. The experimental testing of these predicted spatial patterns of damage may help determine the relative contributions of the two pathological mechanisms hypothesized for ischemic tissue damage.

Amlodipine potentiates metalloproteinase activity and accelerates elastin degradation in a model of aneurysmal disease

AIMS

Abdominal aortic aneurysms are characterised by changes in the extracellular matrix of the arterial media, in particular a reduction in elastin concentration. These changes are mediated by increased levels of endogenous matrix metalloproteinases (MMPs). Recently, calcium channel blockers have been shown to increase the proteolytic activity of MMP-2 secreted by vascular smooth muscle cells. It may therefore by hypothesised that calcium antagonists may potentiate the activity of MMPs in aneurysmal disease and thus accelerate AAA expansion. In this study, the ability of amlodipine--a calcium antagonist--to influence elastin degradation, was assessed in a previously described model of aneurysmal disease.

METHODS

Porcine aortic segments (n = 8) were pre-incubated in exogenous pancreatic elastase for 24 h prior to culture in standard conditions for 6 days with 10 and 100 micrograms/l amlodipine. Control segments were cultured both with and without amlodipine and without elastase. At the termination of culture MMPs were extracted from the tissue and quantified by a combination of substrate gel enzymography and immunoblotting. The volume fractions of elastin and collagen were determined by stereological analysis of EVG stained sections.

RESULTS

Gel enzymography demonstrated significantly increased MMP-9 activity in the amlodipine treated segments, median 4.218 vs. 2.809 arbitrary units (p < 0.01) and this elevated activity was reflected in a significant destruction of medial elastin 27.0 vs. 40.5% (p < 0.05).

CONCLUSION

Therapeutic ranges of amlodipine significantly enhanced elastin degradation and potentiated MMP-9 activity within the aortic organ cultures.

Spreading depression in focal ischemia: a computational study

When a cerebral infarction occurs, surrounding the core of dying tissue there usually is an ischemic penumbra of nonfunctional but still viable tissue. One current but controversial hypothesis is that this penumbra tissue often eventually dies because of the metabolic stress imposed by multiple cortical spreading depression (CSD) waves, that is, by ischemic depolarizations. We describe here a computational model of CSD developed to study the implications of this hypothesis. After simulated infarction, the model displays the linear relation between final infarct size and the number of CSD waves traversing the penumbra that has been reported experimentally, although damage with each individual wave progresses nonlinearly with time. It successfully reproduces the experimental dependency of final infarct size on midpenumbra cerebral blood flow and potassium reuptake rates, and predicts a critical penumbra blood flow rate beyond which damage does not occur. The model reproduces the dependency of CSD wave propagation on N-methyl-D-aspartate activation. It also makes testable predictions about the number, velocity, and duration of ischemic CSD waves and predicts a positive correlation between the duration of elevated potassium in the infarct core and the number of CSD waves. These findings support the hypothesis that CSD waves play an important causal role in the death of ischemic penumbra tissue.

Computational studies of lateralization of phoneme sequence generation

The mechanisms underlying cerebral lateralization of language are poorly understood. Asymmetries in the size of hemispheric regions and other factors have been suggested as possible underlying causal factors, and the corpus callosum (interhemispheric connections) has also been postulated to play a role. To examine these issues, we created a neural model consisting of paired cerebral hemispheric regions interacting via the corpus callosum. The model was trained to generate the correct sequence of phonemes for 50 monosyllabic words (simulated reading aloud) under a variety of assumptions about hemispheric asymmetries and callosal effects. After training, the ability of the full model and each hemisphere acting alone to perform this task was measured. Lateralization occurred readily toward the side having larger size, higher excitability, or higher-learning-rate parameter. Lateralization appeared most readily and intensely with strongly inhibitory callosal connections, supporting past arguments that the effective functionality of the corpus callosum is inhibitory. Many of the results are interpretable as the outcome of a "race to learn" between the model's two hemispheric regions, leading to the concept that asymmetric hemispheric plasticity is a critical common causative factor in lateralization. To our knowledge, this is the first computational model to demonstrate spontaneous lateralization of function, and it suggests that such models can be useful for understanding the mechanisms of cerebral lateralization.

Ultrasound-based quantification of emboli during conventional and endovascular aneurysm repair

PURPOSE

To differentiate and quantify the type and number of lower limb emboli occurring during endovascular aneurysm repair, as compared to conventional surgery.

METHODS

Thirty-eight patients underwent elective infrarenal aneurysm repair using a conventional surgical approach in 18 and an endovascular procedure in 20. Emboli were detected using a Doppler ultrasound system with a 2-MHz transducer interrogating the mid superficial femoral artery. Lower limb emboli were differentiated as particulate or gaseous based on the physical distance traversed by the embolic signal.

RESULTS

Significantly more particulate (median 108 versus 59, p = 0.015) and gaseous (134 versus 46, p = 0.008) emboli were detected during endovascular aneurysm repair as compared to conventional surgery. Clinically, no case of massive microembolization occurred in either group, but one patient in the conventional group required a femoral embolectomy, and three patients undergoing endovascular repair developed self-limiting trash feet postoperatively. In patients undergoing endovascular aortomonoiliac aneurysm repair, there was only a poor correlation between the number of particulate emboli and either procedural duration or operator experience.

CONCLUSIONS

The apparent lack of a relationship between particulate embolization and operative time or technical experience suggests that manipulation of endoluminal devices within the aneurysm sac may not be the sole determinant of intraprocedural embolization. Other as yet undetermined factors may predict patients at high risk for massive embolization.

A computational model of acute focal cortical lesions

BACKGROUND AND PURPOSE

Determining how cerebral cortex adapts to sudden focal damage is important for gaining a better understanding of stroke. In this study we used a computational model to examine the hypothesis that cortical map reorganization after a simulated infarct is critically dependent on perilesion excitability and to identify factors that influence the extent of poststroke reorganization.

METHODS

A previously reported artificial neural network model of primary sensorimotor cortex, controlling a simulated arm, was subjected to acute focal damage. The perilesion excitability and cortical map reorganization were measured over time and compared.

RESULTS

Simulated lesions to cortical regions with increased perilesion excitability were associated with a remapping of the lesioned area into the immediate perilesion cortex, where responsiveness increased with time. In contrast, when lesions caused a perilesion zone of decreased activity to appear, this zone enlarged and intensified with time, with loss of the perilesion map. Increasing the assumed extent of intracortical connections produced a wider perilesion zone of inactivity. These effects were independent of lesion size.

CONCLUSIONS

These simulation results suggest that functional cortical reorganization after an ischemic stroke is a two-phase process in which perilesion excitability plays a critical role.

Comparison of predicted with measured creatinine clearance in cardiac surgical patients

OBJECTIVE

To determine whether creatinine clearance can be determined from a single plasma creatinine measurement in patients up to 5 days after cardiac surgery.

DESIGN

Observational longitudinal study.

SETTING

Cardiac intensive care unit in a tertiary referral center for cardiothoracic surgery.

PATIENTS

Seventy-five patients (54 men, 21 women) scheduled for elective coronary artery surgery (93 postoperative patient days).

INTERVENTIONS

Creatinine clearance measurement using a 4-hour urine collection and a single arterial blood sample.

MEASUREMENTS AND MAIN RESULTS

There was significant agreement (Deming analysis r = 0.63-0.84, correlation r = 0.76-0.95, p < 0.05) between the predicted creatinine clearance and the measured creatinine clearance on each of the postoperative days. This was maintained even if the patients required inotrope or vasoconstrictor therapy, were receiving parenteral nutrition, or had changing renal function (Deming analysis r = 0.67-0.7; correlation r = 0.8-0.93, p < 0.001) but does not apply to patients with preexisting renal dysfunction (Deming analysis r = 0.36; correlation r = 0.57, p = 0.002).

CONCLUSIONS

In cardiac surgical patients with normal preoperative renal function, predicted creatinine clearance is as reliable as measured creatinine clearance up to the fifth postoperative day.

Scalloped wings is the Lucilia cuprina Notch homologue and a candidate for the modifier of fitness and asymmetry of diazinon resistance

The Scalloped wings (Scl) gene of the Australian sheep blowfly, Lucilia cuprina, is shown to be the homologue of the Drosophila melanogaster Notch gene by comparison at the DNA sequence and genetic levels. A L. cuprina genomic fragment, which shows strong identity with the Notch (N) gene at the molecular level, hybridizes to the location of the Scl gene on polytene chromosomes. The two genes are functionally homologous; the dominant and recessive Notch-like phenotypes produced by mutations in the Scl gene allow these alleles to be classed as N-like or Abruptex-like. The Scl gene is under investigation as a candidate for the fitness and asymmetry Modifier (M) of diazinon resistance. We show that M affects the penetrance of wing and bristle phenotypes associated with two Scl alleles in a manner consistent with the M being an allele of Scl. In addition, we report a phenotypic interaction between the diazinon-resistance mutation, Rop-1, and the same alleles of Scl. We propose that the product of Rop-1, an esterase, may be involved in cell adhesion in developmental processes involving the Scl gene product.

Modeling brain adaptation to focal damage

Determining how feature maps in the cerebral cortex adapt to sudden, focal damage is important for gaining a deeper understanding of neurological illnesses such as stroke. In this paper we describe a neural model of the region of primary sensory cortex related to upper extremity proprioception, and show how the feature map there reorganizes following a simulated lesion. A perilesion zone with decreased activity appears and then gradually expands with time. These results differ from those seen with previous models of cortical lesions, and offer an alternative mechanism to the "ischemic penumbra" seen in certain types of stroke.

Automated determination of cross-linked fibrin derivatives in plasma

Automated assays for the measurement of cross-linked fibrin derivatives in plasma (XL-FbDP) have been developed utilizing latex beads coated with anti-D dimer monoclonal antibody (DD-3B6/22) for both the Cobas Fara Chemistry Centrifugal and the Cobas Mira analysers (Roche, Basle, Switzerland). The analysers were programmed to mix plasma and latex reagent simultaneously and analyse absorbance changes over a 10-15 min period. Results were interpolated by the analyser from a standard curve derived from a polymer of D-dimer. Both assays had high precision (< 5% CV) for values between 100 and 1000 ng/ml and provided clear discrimination between normal samples and samples from patients suffering from the thrombotic diseases, DVT/PE and DIC. The results obtained for XL-FbDP determination with both methods compared well with established methods: a high correlation was obtained with a semi-quantitative manual latex method for both the Fara (r = 0.92) and Mira (r = 0.83) and correlations (r) of 0.81 (Fara) and 0.84 (Mira) were obtained with an enzyme immunoassay (EIA). Correlation between the two automated procedures was high (r = 0.96). The automated method will enable laboratories to provide a rapid and accurate quantitation of XL-FbDP.