An immune-protein score combining TRAIL, IP-10 and CRP for predicting severe COVID-19 disease

COVID-19 patients are oftentimes over- or under-treated due to a deficit in predictive management tools. This study reports derivation of an algorithm that integrates the host levels of TRAIL, IP-10, and CRP into a single numeric score that is an early indicator of severe outcome for COVID-19 patients and can identify patients at-risk to deteriorate. 394 COVID-19 patients were eligible; 29% meeting a severe outcome (intensive care unit admission/non-invasive or invasive ventilation/death). The score's area under the receiver operating characteristic curve (AUC) was 0.86, superior to IL-6 (AUC 0.77; p = 0.033) and CRP (AUC 0.78; p < 0.001). Likelihood of severe outcome increased significantly (p < 0.001) with higher scores. The score differentiated severe patients who further deteriorated from those who improved (p = 0.004) and projected 14-day survival probabilities (p < 0.001). The score accurately predicted COVID-19 patients at-risk for severe outcome, and therefore has potential to facilitate timely care escalation and de-escalation and appropriate resource allocation.

Interferon gamma-induced protein 10 (IP-10) for the early prognosis of the risk for severe respiratory failure and death in COVID-19 pneumonia

OBJECTIVES

Elevated concentrations of soluble urokinase plasminogen activator receptor (suPAR) predict progression to severe respiratory failure (SRF) or death among patients with COVID-19 pneumonia and guide early anakinra treatment. As suPAR testing may not be routinely available in every health-care setting, alternative biomarkers are needed. We investigated the performance of C-reactive protein (CRP), interferon gamma-induced protein-10 (IP-10) and TNF-related apoptosis-inducing ligand (TRAIL) for predicting SRF or death in COVID-19.

METHODS

Two cohorts were studied; one discovery cohort with 534 patients from the SAVE-MORE clinical trial; and one validation cohort with 364 patients from the SAVE trial including also 145 comparators. CRP, IP-10 and TRAIL were measured by the MeMed Key® platform in order to select the biomarker with the best prognostic performance for the early prediction of progression into SRF or death.

RESULTS

IP-10 had the best prognostic performance: baseline concentrations 2000 pg/ml or higher predicted equally well to suPAR (sensitivity 85.0 %; negative predictive value 96.6 %). Odds ratio for poor outcome among anakinra-treated participants of the SAVE-MORE trial was 0.35 compared to placebo when IP-10 was 2,000 pg/ml or more. IP-10 could divide different strata of severity for SRF/death by day 14 in the validation cohort. Anakinra treatment decreased this risk irrespective the IP-10 concentrations.

CONCLUSIONS

IP-10 concentrations of 2,000 pg/ml or higher are a valid alternative to suPAR for the early prediction of progression into SRF or death the first 14 days from hospital admission for COVID-19 and they may guide anakinra treatment.

TRIAL REGISTRATION

CLINICALTRIALS

gov, NCT04680949 and NCT04357366.

32. Host Immune-Protein Signature Combining TRAIL, IP-10 and CRP for Early and Accurate Prediction of Severe COVID-19 Outcome

Background

Accurately identifying COVID-19 patients at-risk to deteriorate remains challenging. Dysregulated immune responses impact disease progression and development of life-threatening complications. Tools integrating host immune-protein expression have proven useful in determining infection etiology and hold potential for prognosticating disease severity.

Methods

Adults with COVID-19 were enrolled at medical centers in Israel, Germany, and the United States (Figure 1). Severe outcome was defined as intensive care unit admission, non-invasive or invasive ventilation, or death. Tumor necrosis factor related apoptosis inducing ligand (TRAIL), interferon gamma inducible protein-10 (IP-10) and C-reactive protein (CRP) were measured using an analyzer providing values within 15 minutes (MeMed Key®). A signature indicating the likelihood of severe outcome was derived generating a score (0-100).

Description of derivation cohort

RT-PCR, reverse transcription polymerase chain reaction.

Results

Between March and November 2020, 518 COVID-19 patients were enrolled, of whom 394 were eligible, 29% meeting a severe outcome. Age ranged between 19-98 (median 61.5), with 59.1% male. Patients meeting severe outcomes exhibited higher levels of CRP and IP-10 and lower levels of TRAIL (Figure 2; p < 0.001). Likelihood of severe outcome increased significantly (p < 0.001) with higher scores. The signature’s area under the receiver operating characteristic curve (AUC) was 0.86 (95% confidence interval: 0.81-0.91). Performance was not confounded by age, sex, or comorbidities and was superior to IL-6 (AUC 0.77; p = 0.033) and CRP (AUC 0.78; p < 0.001). Clinical deterioration proximal to blood draw was associated with higher signature score. Scores of patients meeting a first outcome over 3 days after blood draw were significantly (p < 0.001) higher than scores of non-severe patients (Figure 3). Moreover, the signature differentiated patients who further deteriorated after meeting a severe outcome from those who improved (p = 0.004) and projected 14-day survival probabilities (p < 0.001; Figure 4).

TRAIL, IP-10, CRP and the severity signature score are differentially expressed in severe and non-severe COVID-19 infection

Dots represent patients and boxes denote median and interquartile range (IQR)

The signature score of patients meeting a severe outcome on or after the day of blood draw is significantly (p < 0.001) higher than the signature score of non-severe patients.

Dots represents patients and boxes denote median and IQR

Kaplan-Meier survival estimates for signature score bins

Conclusion

The derived signature combined with a rapid measurement platform has potential to serve as an accurate predictive tool for early detection of COVID-19 patients at risk for severe outcome, facilitating timely care escalation and de-escalation and appropriate resource allocation.

Disclosures

Alon Angel, n/a, MeMed (Employee, Shareholder) Niv Samuel Mastboim, BSc, MeMed (Employee, Shareholder) Oded Shaham, PhD, MeMed (Employee, Shareholder) Tahel Ilan Ber, MD, MeMed (Employee, Shareholder) Roy Navon, MSc, MeMed (Employee, Shareholder) Einav Simon, PhD, MeMed (Employee, Shareholder) Michal Rosenberg, PhD, MeMed (Employee) Yael Israeli, PhD, MeMed (Employee) Mary Hainrichson, PhD, MeMed (Employee, Shareholder) Noa Avni, PhD, MeMed (Employee) Eran Reiner, MD, MeMed (Employee) Kfir Oved, MD, PhD, MeMed (Board Member, Employee, Shareholder) Ilya Kagan, MD, MeMed (Scientific Research Study Investigator) Shaul Lev, M.D, MeMed (Scientific Research Study Investigator) Dror Diker, MD, MeMed (Scientific Research Study Investigator) Amir Jarjou’i, MD, MeMed (Scientific Research Study Investigator) Ramzi Kurd, MD, MeMed (Scientific Research Study Investigator) Guy Danziger, MD, MeMed (Scientific Research Study Investigator) Cihan Papan, MD, MeMed (Scientific Research Study Investigator) Sergey Motov, MD, MeMed (Scientific Research Study Investigator) Maanit Shapira, Ph.D, MeMed (Scientific Research Study Investigator) Tanya Gottlieb, PhD, MeMed (Employee, Shareholder) Eran Eden, PhD, MeMed (Board Member, Employee, Shareholder)

EOSINOPENIA COMO FATOR PREDITIVO DE GRAVIDADE EM PACIENTES PEDIÁTRICOS INTERNADOS POR COVID-19

Objetivo

Materiais e métodos

Resultados

Discussão

Conclusão

[ON THE EQUATOR]

Elective clerkships in low income countries have been an integral part of the curriculum in the majority of medical schools worldwide. These programs expose students to global challenges, to a diversity of cultures and healthcare systems, and have been shown to improve medical knowledge, as well as clinical and communication skills. In 2018 and 2019, the Faculty of Medicine at the Technion, in cooperation with the Department for Infectious Diseases in the Rambam Health Care campus and the "Brit Olam" nonprofit organization, offered a clinical clerkship in Kiboga hospital, Uganda. The elective took place in a public governmental hospital located in one of the poorest districts of Uganda. During a three-week period, the students accompanied by Israeli and Uganda tutors, participated in clinical rounds and other clinical activities in various departments of the hospital. This manuscript, describes the students' experiences in Kiboga. During the short elective, students had a unique opportunity to observe a different culture, immerse in a completely different healthcare system, learn about how a detailed medical history and a thorough physical examination can lead to diagnosis (without extensive diagnostic tests), and closely observe ethical challenges and difficult clinical decisions. The elective helped students develop personally and professionally and solidify their commitment to medicine. Currently, in Israeli medical schools, there are a few programs which expose students to medicine in low-resource countries. We believe that expanding the understanding of Global Health through courses and overseas opportunities in long-term partnerships, can improve the students' medical education.

426. Use of Real Time IP-10 Measurements to Identify and Monitor the Dysregulated Immune Response in COVID-19 Patients

Background

It is estimated that up to 10% of SARS-CoV-2 patients progress from early and pulmonary stages to the most severe stage of illness, which manifests as an extra-pulmonary systemic hyperinflammatory syndrome. Interferon gamma-induced protein 10 (IP-10) is an inflammatory marker that plays a role in the dysregulated host response of COVID-19 infected patients. Clinical monitoring of IP-10 has been restricted in the absence of a rapid diagnostic test. MeMed Key^TM is a novel platform recently cleared to provide IP-10 measurements in 15 minutes. We hypothesized that providing physicians with real time IP-10 measurements would support detection and continuous monitoring of patients with a dysregulated immune response and potentially allow personalized immunomodulation to improve patient outcome.

IP-10 levels reflect corticosteroid treatment

Methods

From 7^th April 2020 to 10^th May 2020 blood was routinely collected serially from 52 SARS-CoV-2 positive patients hospitalized at a COVID-19 dedicated medical center. A clinical decision support protocol was in place focused on managing viral response, oxygenation and inflammatory state (NCT04389645).

Results

The median age of the 52 patients was 69, 69% were male, 21% were ventilated, 4 died, 2 due to non-COVID-19 related complications. The most common comorbidities were Diabetes 40% and Hypertension 46%. IP-10 >1000 pg/ml correlated with ICU admission (p< 0.05) and increased COVID-19 severity score (p< 0.01). 19 of the 52 patients had IP-10 >1000 pg/ml, of these 12 were treated with corticosteroids. Monitoring IP-10 within the clinical decision support protocol assisted with personalized corticosteroid regimens with the aim of reducing IP-10 < 1000 pg/ml. The 10 patients that survived exhibited IP-10 levels >1000 pg/ml for 2.6 days on average. In contrast, the 2 patients that died of COVID-19 related complications displayed an average of 7.5 days with IP-10 >1000 pg/ml (p< 0.05).

Conclusion

Providing physicians with real time measurements of IP-10 in COVID-19 patients proved a useful tool as part of the clinical decision support protocol. Timely identification, monitoring and personalized treatment of COVID-19 patients exhibiting a dysregulated immune response may aid in improving patient outcome. Further studies are warranted.

Disclosures

Tahel Ilan Ber, MD, MeMed (Employee) Alon Angel, n/a, MeMed (Employee) Lior Kellerman, M.D, MeMed (Employee) Eran Barash, MA, MeMed (Employee) Roy Navon, MSc, MeMed (Employee) Einav Simon, PhD, MeMed (Employee) Noa Avni, PhD, MeMed (Employee) Mary Hainrichson, PhD, MeMed (Employee) Tanya Gottlieb, PhD, MeMed (Employee) Kfir Oved, MD, PhD, MeMed (Employee) Eran Eden, PhD, MeMed (Employee)

Regulation of visceral adipose tissue-derived serine protease inhibitor by nutritional status, metformin, gender and pituitary factors in rat white adipose tissue

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is a recently discovered adipocytokine mainly secreted from visceral adipose tissue, which plays a main role in insulin sensitivity. In this study, we have investigated the regulation of vaspin gene expression in rat white adipose tissue (WAT) in different physiological (nutritional status, pregnancy, age and gender) and pathophysiological (gonadectomy, thyroid status and growth hormone deficiency) settings known to be associated with energy homeostasis and alterations in insulin sensitivity. We have determined vaspin gene expression by real-time PCR. Vaspin was decreased after fasting and its levels were partially recovered after leptin treatment. Chronic treatment with metformin increased vaspin gene expression. Vaspin mRNA expression reached the highest peak at 45 days in both sexes after birth and its expression was higher in females than males, but its levels did not change throughout pregnancy. Finally, decreased levels of growth hormone and thyroid hormones suppressed vaspin expression. These findings suggest that WAT vaspin mRNA expression is regulated by nutritional status, and leptin seems to be the nutrient signal responsible for those changes. Vaspin is influenced by age and gender, and its expression is increased after treatment with insulin sensitizers. Finally, alterations in pituitary functions modify vaspin levels. Understanding the molecular mechanisms regulating vaspin will provide new insights into the pathogenesis of the metabolic syndrome.

Subcellular distribution of theEntamoeba histolytica140 kDa FN-binding molecule during host-parasite interaction

Entamoeba histolyticatrophozoites recovered from the host-parasite interface during abscess development obtain different stimuli compared with long-term cultured cells. In order to have a better understanding about the mechanisms in which the 140 kDa fibronectin (FN)-binding molecule (EhFNR) is involved during the invasive process, we decided to compare the regulation process of this molecule among long-term cultured trophozoites, FN-stimulated trophozoites, and trophozoites recently recovered from a liver abscess. A cDNA clone (5A) containing a fragment of theEhFNR that shows identity to the C-terminal region of the intermediate galactose lectin subunit Igl, was selected with a mAb (3C10). Identity ofEhFNR with Igl was confirmed by immunoprecipitation with 3C10 and EH3015 (against the Gal/GalNAc intermediate subunit) mAbs. The 3C10 mAb was used as a tool to explore the modulation of the amoebic receptor (EhFNR). Our results showed specific regulation of theEhFNR in FN-interacted amoebas, as well as in trophozoites recovered at different stages of abscess development. This regulation involved mobilization of the receptor molecule from internal vesicles to the plasma membrane. Therefore, we suggest that in the host-parasite interface, theEhFNR (Igl) plays an important role in the adhesion process during abscess development.

Activation of the stress protein response prevents the development of pulmonary edema by inhibiting VEGF cell signaling in a model of lung ischemia-reperfusion injury in rats

Lung endothelial damage is a characteristic morphological feature of ischemia-reperfusion (I/R) injury, although the molecular steps involved in the loss of endothelial integrity are still poorly understood. We tested the hypothesis that the activation of vascular endothelial growth factor (VEGF) cell signaling would be responsible for the increase in lung vascular permeability seen early after the onset of I/R in rats. Furthermore, we hypothesized that the I/R-induced pulmonary edema would be significantly attenuated in rats by the activation of the stress protein response. Pretreatment with Ad Flk-1, an adenovirus encoding for the soluble VEGF receptor type II, prevented I/R-mediated increase in lung vascular permeability in rats. Furthermore, the I/R-induced lung injury was significantly decreased by prior activation of the stress protein response with geldanamycin or pyrrolidine dithiocarbamate. In vitro studies demonstrated that VEGF caused an increase in protein permeability across primary cultures of bovine macro- and microvascular lung endothelial cell monolayers that were associated with a phosphorylation of VE- and E-cadherin and the formation of actin stress fibers. Activation of the stress protein response prevented the VEGF-mediated changes in protein permeability across these cell monolayers and reduced the phosphorylation of VE-and E-cadherins, as well as the formation of actin stress fibers in these cells.

Migrating from target-controlled infusion to closed-loop control in general anaesthesia

The target-controlled infusion (TCI) technique has been successfully and commercially used in clinical general anaesthesia with the intravenous anaesthetic agent propofol. The technique is based on a population pharmacokinetic model and is an open-loop control system. Closed-loop control requires a reliable and consistent signal for feedback utilisation. With all anaesthetic agents the somatosensory evoked potentials (SEP) have been shown to give increased latency as anaesthetic depth is increased. Using infusion rate and SEP response data from rats anaesthetised with propofol a mathematical model was derived to describe the anaesthetic process. This model was used as a design reference to develop a proportional integral (PI) closed-loop control system using SEP as the feedback measure. A serials of 10 trials were conducted to investigate the difference between continuous bolus injection and infusion, all under closed-loop control. The trials showed that the use of SEPs in closed-loop control of anaesthesia is feasible.

Neuronal network modelling of the effects of anaesthetic agents on somatosensory pathways

The whole question of consciousness, awareness and depth of anaesthesia is both timely, little understood and deeply challenging. Models of the underlying neural pathway mechanisms/dynamics are necessary for understanding the interactions involved and their structure and function. A neuronal network of the somatosensory pathways is proposed in this paper based on experimental information and physiological investigation into anaesthesia. Existing mathematical neuronal models from the literature have been modified and then employed to describe the dynamics of the proposed pathway network. Effects of anaesthetic agents on the cortex were simulated in the model which describes the evoked cortical responses. By comparison with responses from anaesthetised rats, the model's responses are able to describe the dynamics of typical responses. Thus, the proposed model promises to be valuable for investigating the mechanisms of anaesthesia on the cortex and the effects of brain lesions.

Renovascular hypertension associated with neurofibromatosis: two cases and review of the literature

The authors report two cases of renovascular hypertension associated with neurofibromatosis. A 19-year-old woman was admitted to our hospital with a complaint of abdominal pain and blood pressure of 180/120 mmHg. Examination revealed café-au-lait spots over her chest and extremities. Peripheral plasma renin activity (PRA) under basal conditions was 2.8 ng/ml/h and increased to 12.6 ng/ml/h after administration of 50 mg captopril. Plasma and urinary catecholamines were normal. Selective renal angiography showed left aneurysmal dilatation of the segmentary branch and right renal artery stenosis with multiple aneurysmal affecting different branches. Blood pressure was controlled by multiple drugs, including beta-blockers and angiotensin-converting enzyme inhibitor. Another patient, a 20-year-old woman, was admitted because of severe arterial hypertension, numerous café-au-lait spots, scoliosis, and mass over the right arm. PRA from the right renal vein was extremely elevated, and selective angiography demonstrated bilateral renal artery stenosis. Aortorenal bypass was performed successfully.

Somatosensory evoked potentials for closed-loop control of anaesthetic depth using propofol in the urethane-anaesthetized rat

Primary somatosensory cortical mass responses have been shown to exhibit dose-dependent changes in latency when general anaesthetics are administered. Here we describe a system in which the latency of evoked responses was measured automatically in real time in five animals. Latency changes were used to operate a closed-loop control of propofol delivery by intravenous infusion. The system attempted to induce and maintain a 1 ms increase in evoked response latency; this was reversed when infusion was discontinued. Allowing for the rapid and large biological fluctuations in the evoked response, this was achieved successfully. The system maintained a mean increase in latency of 1.27 (SD 0.42) ms. The mean statistical dispersion index of data obtained during the controlled period was 1.23 (0.3); in an ideal controllable system it approximates to 1. Such a system may provide a means for the automatic delivery of anaesthetics.

Comparison between digestive endoscopy and 24-hour esophageal pH monitoring for the diagnosis of gastroesophageal reflux esophagitis: "presentation of 100 cases"

BACKGROUND/AIMS

We present the results obtained from 100 new cases of clinical esophagitis caused by gastroesophageal reflux at the Hospital of Caldas and at the Service of Gastroenterology of VIME (Endoscopical Video Medicine) in Manizales, Caldas, Colombia; between the months of June and November of 1996, evaluated by digestive endoscopy and classified based on the New Savary-Miller 5-Grade Classification.

METHODOLOGY

The patients were selected based on the presence of symptomatology suggestive of esophagitis caused by gastroesophageal reflux; an endoscopy was performed followed by 24-hour esophageal pH monitoring. The patients were grouped according to their grade of esophagitis in the New Savary-Miller Classification. The central analysis was focused on determining the existing relationship between the observed esophagitis and the results obtained by the 24-hour esophageal pH monitoring.

RESULTS

Findings show that 51% and 48% of patients with esophagitis grades 1 and 2 had a normal DeMeester's score (< 14.7) in channel 1. In channel 2 we found normal scores in 86% and 82% of esophagitis grades 1 and 2, respectively.

CONCLUSIONS

We ask whether the average level of pathological reflux of 14.7 can be extrapolated to our population; also whether endoscopical overdiagnosis of esophagitis caused by gastroesophageal reflux exists, or if non-recognized causes of esophagitis exist. Another question is if it is justified to order 24-hour esophageal pH monitoring in patients with grades 1 and 2 esophagitis.

The effect of etomidate on sensory transmission in the dorsal column pathway in the urethane-anaesthetized rat

The effect of Etomidate, a general anaesthetic, on sensory afferent transmission was measured in the dorsal column pathway in urethane-anaesthetized rats. Extracellular recordings were made of peripherally evoked responses by single cells in the cuneate nucleus, ventroposterolateral nucleus of the thalamus and laminae IV-VI of the primary somatosensory cortex. Cortical mass responses were also recorded. In further experiments, cortical mass responses were evoked antidromically by stimulation in the pyramidal tract. The effect of incremental administration of Etomidate on evoked responses was recorded. These results are compared with the previously reported effects of urethane, a 'conventional' anaesthetic. Etomidate did not alter cuneate or ventroposterolateral thalamic cell responses but it caused a dose-dependent reduction in cortical cell responsiveness. It failed to alter antidromically evoked cortical mass responses. Etomidate differs from the majority of anaesthetics, which act in the thalamus, and appears to cause perturbation at the cortical level.

Estimation of latency changes and relative amplitudes in somatosensory evoked potentials using wavelets and regression

Changes in onset latency and relative amplitudes of somatosensory evoked potentials (SEP) may be a convenient and reliable neurophysiological indicator of depth of anesthesia. However, to derive the components is very difficult mathematically and visual inspection or alternatively the peak-latency estimation is usually employed. A methodology for estimating the components was developed for both real-time and off-line applications based on the combination of the wavelet transforms (WT), geometric analysis, artificial intelligence (AI), and mathematical analysis of the first positive wave of SEPs. The WT together with AI constitutes a feature extraction engine for localizing the first positive peak and negative valley and hence relative amplitudes. The latency change between two averages is obtained by shifting one average toward another to achieve a best match along the positive inflections. The inflection, based on the peak, is modeled as a regression line and is refined using a steepness inference algorithm. Results from simulation and anesthetized rats show that it is reliable in comparison with visual inspection, robust to amplitude variation and signal distortion, and efficient in computation, and hence it is suitable for automation. Comparisons of interobserver variability and analysis of method agreement suggest that the method can be used as a substitute for estimations by visual inspection.

Increased secretion of cholesteryl ester transfer protein from hamster adipose tissue: stimulation by beta-adrenergic agents

High levels of cholesteryl ester transfer protein (CETP) favours decreased plasma high density lipoprotein cholesterol and increased levels of cholesterol in apolipoprotein B containing lipoproteins. Adipose tissue is one of the major sources of circulating CETP. Previous studies by our group and others demonstrated that the production of CETP from hamster adipose tissue increases after fasting, a metabolic state known to affect the sympathoadrenal axis. The present study examines the influence of beta-adrenergic agonists on the secretion of CETP from hamster adipose tissue. Fifteen minutes after an intraperitoneal injection of isoproterenol (12 microg/kg), the release of CETP mass and activity from adipose tissue fragments incubated in vitro were significantly increased. This was associated with an elevation in CETP mass and activity in plasma. The effects of isoproterenol on CETP release from adipose tissue and plasma CETP levels were suppressed by propranolol, a beta-adrenoceptor inhibitor. Addition of 10(-6) M isoproterenol to adipose tissue in vitro increased the release of CETP mass and activity from adipose tissue and this was also blocked by propranolol. Isoproterenol-induced secretion of CETP activity from adipose tissue was partially inhibited by cytochalasin B, an inhibitor of actin cytoskeleton reorganization. Forskolin, a classical adenylate cyclase agonist and 8-bromo-cAMP, a functional analogue of cAMP, mimicked the effect of isoproterenol on CETP release from adipose tissue. Our results suggest that isoproterenol increases the secretion of CETP from hamster adipose tissue through a beta-adrenoceptor and a cAMP-dependent pathway. Actin cytoskeleton reorganization may be required for secretion of CETP. The findings imply that the secretion of CETP from adipose tissue is under neurosympathetic control.

The effect of chemoreceptor stimulation on the centripetal transfer of somatosensory information in the urethane-anaesthetized rat

In urethane-anaesthetized rats, stimulation of carotid body chemoreceptors desynchronizes the cortical electroencephalogram and increases the sensitivity of thalamic and cortical somatosensory neurones to peripheral sensory nerve stimulation. Peripheral chemoreceptors were stimulated by injecting a bolus (30 ml) or infusing 100 ml of 0.18 M NaCl solution equilibrated with 100% CO2 into an internal carotid artery, the cortical electroencephalogram and ventilation were monitored routinely. This stimulus induced hyperventilation and desynchronization of the cortical electroencephalogram. Anaesthetized rats also showed spontaneous periodic increases in ventilation rate accompanied by changes of the cortical electroencephalogram from high-voltage low frequency to low-voltage high frequency which seemed to be identical with those evoked by stimulating chemoreceptors. The activity of identified somatosensory neurons in the thalamic ventrobasal complex, layer IV of the somatosensory cortex, or the cuneate nucleus was recorded extracellularly during and following chemoreceptor activation. Neurones in the ventrobasal thalamus and somatosensory cortex showed a decrease in latency and an increase in probability of discharge to supramaximal electrical stimulation of the forepaw which was more pronounced following infusion stimulation of the carotid body than following bolus stimulation. In contrast, neurons within the cuneate nucleus showed a slight increase in latency to onset and a decrease in the probability of firing following the same stimulus. The results indicate that stimulation of the carotid body chemoreceptors leads to an enhancement of the response of somatosensory neurons to their normal physiological input.

Relationship between lipoprotein lipase and high density lipoprotein cholesterol in mice: modulation by cholesteryl ester transfer protein and dietary status

Plasma lipoprotein lipase (LPL) activity correlates with high density lipoprotein (HDL) cholesterol levels in humans. However, in several mouse models created either through transgenesis or targeted inactivation of LPL, no significant changes in HDL cholesterol values have been evident. One possible explanation for this species difference could be the absence of plasma cholesteryl ester transfer protein (CETP) activity in mice. To explore this possibility and further investigate interactions between LPL and CETP modulating HDL cholesterol levels in vivo, we examined the relationship between LPL activity and HDL levels in mice expressing the simian CETP transgene, compared with littermates not carrying the CETP gene. On a chow diet, increasing LPL activity was associated with a trend towards increased HDL levels (51 +/- 29 vs. 31 +/- 4 mg/dL highest vs. lowest tertiles of LPL activity, P = 0.07) in mice expressing CETP, while no such effects were seen in the absence of CETP (65 +/- 12 vs. 61 +/- 15 mg/ dL). Furthermore, in the presence of CETP, a significant positive correlation between LPL activity and HDL cholesterol was evident (r = 0.15, P = 0.006), while in the absence of CETP no such correlation was detected (r = 0.15, P = 0.36), highlighting the interactions between LPL and CETP in vivo. When mice were challenged with a high fat, high carbohydrate diet, strong correlations between LPL activity and HDL cholesterol were seen in both the presence (r = 0.45, P = 0.03) and absence (r = 0.73, P < 0.001) of CETP. Therefore, under altered metabolic contexts, such as those induced by dietary challenge, the relation between LPL activity and HDL cholesterol may also become evident. Here we have shown that both genetic and environmental factors may modulate the association between LPL activity and HDL cholesterol, and provide explanations for the absence of any changes in HDL values in mice either transgenic or with targeted disruption of the LPL gene.

Regional and rural-urban differences in obesity in Canada. Canadian Heart Health Surveys Research Group

OBJECTIVE

To describe regional and rural-urban differences in weight and weight loss patterns in Canadian adults.

DESIGN

Population-based, cross-sectional surveys.

SETTING

Nine Canadian provinces (excluding Nova Scotia) from 1986 to 1992.

PARTICIPANTS

A probability sample of 27,120 men and women aged 18 to 74 years was selected using the health insurance registration files in each province. Anthropometry was performed on 18,043 participants (67%).

OUTCOME MEASURES

Region of Canada (Atlantic, central, western); rural or urban residence (rural if participant resided in a community whose population was < 10,000, urban if population > or = 10,000); body mass index (BMI, kg/m2); percentage of participants trying to lose weight; reasons for trying to lose weight; level of leisure-time physical activity.

RESULTS

Overall, mean BMI values in rural men (26.1 kg/m2) and women (25.3 kg/m2) were not significantly different from urban counterparts (25.7 kg/m2 and 24.8 kg/m2, respectively). Similarly, obesity (BMI > or = 27 kg/m2) was as prevalent in rural men (37%) and women (30%) as in urban participants (34% and 28%, respectively). However, a difference was observed in western Canada where 41% of rural and 34% of urban men were obese (odds ratio [OR], adjusted for age and education = 1.29; 95% confidence interval [CI] 1.06, 1.57), as were 35% of rural and 25% of urban women (OR, adjusted for age and education = 1.47; 95% CI 1.17, 1.84). Among men in western Canada, the rural-urban differences were greatest in the 25-64 year age group, whereas in women the differences were present at all ages. Overall, in Canada, urban men (26%) are more likely than rural men (23%) to be trying to lose weight; the reverse was true for women (39% and 42%, respectively).

CONCLUSION

Considerable regional and rural-urban differences are seen in the patterns of weight and weight loss in Canada. A fuller understanding of the underlying behavioural determinants of these differences is needed. On the basis of such an understanding, effective programs to promote healthy weights for individuals and communities in these areas might be developed.

Cure of Helicobacter pylori infection improves gastric acid secretion in patients with corpus gastritis

BACKGROUND

For more than 30 years it has been known that gastric acid secretion is inversely related to the extent and severity of corpal gastritis. We therefore evaluated the effect of cure of Helicobacter pylori infection on basal and pentagastrin-stimulated acid secretion.

METHODS

Basal acid output (BAO) and maximal acid output (MAO) were assessed in 11 H. pylori-infected dyspeptic patients (8 women and 3 men; mean age, 28 years) before and after successful anti-H. pylori therapy.

RESULTS

The gastritis index was significantly lower after therapy and was associated with an increase in both BAO and MAO after cure of the H. pylori infection (BAO from 0.3 mmol/h and MAO from 4.8 mmol/h to 19 mmol/ h). Basal and stimulated acid concentrations also increased (29.1 +/- 36.6 to 54 +/- 31 mmol/l and 72.5 +/- 46 to 120.1 +/- 30 mmol/l, respectively, for basal and stimulated acid concentrations; P < 0.05 for peak and MAO, P = 0.07 for BAO).

CONCLUSION

Gastric acid secretion increased into the normal range after successful treatment of H. pylori infection, suggesting that gastric function can recover to normal or almost normal after cure of H. pylori infection.

The association of cardiovascular disease risk factors with abdominal obesity in Canada. Canadian Heart Health Surveys Research Group

OBJECTIVE

To assess the degree of association of abdominal obesity with blood pressure and plasma lipid levels and to determine which anthropometric measures of obesity are most closely associated with these cardiovascular risk factors.

DESIGN

Population-based, cross-sectional surveys.

SETTING

Five Canadian provinces (Alberta, Manitoba, Ontario, Quebec and Saskatchewan) between 1989 and 1992.

PARTICIPANTS

A probability sample of 16,007 men and women aged 18 to 74 was selected using health insurance registration files in each province and invited to participate. A complete set of measurements was available for 8974 (56%) adults.

OUTCOME MEASURES

Initially, simple correlation analyses by age and sex were performed between the anthropometric variables-body mass index, waist circumference (WC), hip circumference (HC), ratio of waist to hip circumference (WHR)- and cardiovascular disease risk variables-systolic blood pressure (SBP), diastolic blood pressure (DBP), levels of total cholesterol (TC), low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides (TRIG) and the TC/HDL ratio. Canonical correlation analyses were performed to determine the multivariate associations between the anthropometric and risk variables.

RESULTS

The simple correlations between anthropometric variables and cardiovascular disease risk variables were highest for SBP; moderate for DBP, HDL, TRIG and TC/HDL; and lowest for LDL and TC. Of the anthropometric variables, WC demonstrated the greatest correlations with the risk variables. The first canonical correlations were significant (p < 0.0001) in men (0.58) and women (0.61) of all ages. Of the anthropometric variables, WC consistently demonstrated the highest loading values in the first canonical variable in men (0.56) and women (0.59). Of the risk variables in both sexes, the loadings of TRIG were generally the largest, those of HDL, SBP, DBP intermediate and those of LDL the smallest. In men, the strength of these associations generally decreased with age, whereas in women they peaked in the 35-54 year age group.

CONCLUSION

Considerable association was seen between measures of abdominal obesity and blood pressure and plasma lipid levels. WC is the measure of abdominal obesity most highly correlated with these cardiovascular disease risk factors.

Furazolidone, amoxycillin, bismuth triple therapy for Helicobacter pylori infection

BACKGROUND

Metronidazole-resistant Helicobacter pylori are generally the rule in developing countries such as Colombia. Developing countries need an effective, simple and inexpensive non-metronidazole therapy for H. pylori infection.

AIM

To evaluate the combination of bismuth, furazolidone and amoxycillin for the treatment of H. pylori infection in Colombia.

METHODS

Thirty patients with histologically documented H. pylori infection received the combination of bismuth subcitrate 240 mg b.d., furzolidone 100 mg q.d.s. and amoxycillin 500 mg q.d.s. for 14 days. Four or more weeks after ending therapy patients were re-endoscoped and gastric biopsies were obtained and examined using the Genta stain. Each slide was scored for presence, absence and density of H. pylori, active and chronic inflammation, intestinal metaplasia, erosions and atrophy. Cure was defined as the absence of H. pylori.

RESULTS

All patients completed the course of therapy. Twenty-five patients were cured (86%, 95% CI: 65-94%). Mild, well-tolerated side-effects were reported by six patients (20%).

CONCLUSIONS

This combination of bismuth, furazolidone and amoxycillin fulfills the criteria for successful H. pylori therapy and appears particularly well suited for developing countries since it is simple, inexpensive and effective. Furazolidone-containing therapies may become especially useful in the face of a world-wide increase in H. pylori resistance to metronidazole and macrolides.

Inhibition by hirulog-1 of generation of plasminogen activator inhibitor-1 from vascular smooth-muscle cells induced by thrombin

Hirulog-1 effectively prevents thrombosis in coronary artery disease and is associated with a low incidence of bleeding complications. Our study characterized the effect of Hirulog-1 on thrombin-induced production of plasminogen activator inhibitor-1 (PAI-1) in cultured baboon aortic smooth-muscle cells (BASMCs). Thrombin increased the steady-state levels of PAI-1 messenger RNA (mRNA) and the release of PAI-1 antigen from BASMCs. Treatments with 10-20 mg/L of Hirulog-1 inhibited >80% of thrombin-induced PAI-1 generation from BASMCs. Hirulog-1 alone did not significantly alter PAI-1 production in the absence of thrombin. Significant reduction of thrombin-induced PAI-1 release was observed in cultures treated with Hirulog-1 for 1 h. The maximal effect of Hirulog-1 on thrombin-induced PAI-1 release was achieved in cultures treated with thrombin plus Hirulog-1 for 3 to 6 h, associated with the normalization of PAI-1 mRNA levels induced by thrombin treatment. Strong inhibition by Hirulog-1 on thrombin-induced PAI-1 release remained in cultures with 8 h of the treatment, but the effect was attenuated 16 h after a single addition of the inhibitor. Our study demonstrates that Hirulog-1 effectively inhibited thrombin-induced PAI-1 production in cultured vascular SMCs at mRNA and protein levels. Vascular SMCs may be exposed to high concentrations of thrombin when endothelium is injured. The information generated from this study suggests that Hirulog-1 potentially prevents intravascular thrombogenesis through inhibiting thrombin-induced PAI-1 production in vascular SMCs, especially when hypercoagulation and endothelial injury occurs.

G proteins and phospholipase C mediate thrombin-induced generation of plasminogen activator inhibitor-1 from vascular smooth muscle cells

The present study investigated transcellular signalling mechanism involved in thrombin-induced production of plasminogen activator inhibitor-1 (PAI-1) in cultured vascular baboon aortic smooth muscle cells (BASMC). Treatments with thrombin dose-dependently increased the steady state levels of PAI-1 mRNA and the generation of PAI-1 antigen from BASMC. Thrombin receptor-activating peptide mimicked the effect of thrombin on the generation of PAI-1. Sodium fluoride (1 mM) stimulated PAI-1 generation from BASMC. Pertussis toxin dose-dependently suppressed thrombin-induced increase of PAI-1 generation. Treatment with 5 mM neomycin, 10 microM U73122 or 1 microM calphostin C blocked thrombin-induced PAI-1 generation. Phorbol myristate acetate at 10 nM for 3 h strongly stimulated the generation of PAI-1 from BASMC. Forskolin (100 microM) or 8-bromo-cAMP (100 microM) suppressed thrombin-induced PAI-1 generation. The responses of quiescent BASMC to thrombin or the inhibitors on PAI-1 generation were comparable to that of growing cells. The results of the present study suggest that pertussis toxin-sensitive G proteins and a phospholipase C are involved in thrombin-induced generation of PAI-1 in BASMC, which may transmit signals from occupied thrombin receptor to protein kinase C and thereby increase the generation of PAI-1. Elevated levels of intracellular cAMP may negatively regulate the generation of PAI-1 from vascular SMC.

Lipid structure of rat adipocyte plasma membranes following dietary lard and fish oil

We have determined the changes in the lipid structure of the adipocyte plasma membranes of rats receiving lard or fish oil in their diet. For this purpose, mature Wistar rats were fed 20% (w/w) lard or fish oil diets for 22 days, when the plasma membranes of the epididymal and perirenal adipocytes were prepared. Detailed analysis of the membrane lipids by chromatographic methods showed that dietary fat exerted a major effect on the lipid class and molecular species composition of the phospholipids. As a result of fish oil feeding, significant increases in the 20:5(n-3), 22:5(n-3) and 22:6(n-3) were detected in all glycerophospholipid classes, while the 18:1(n-9) and 18:2(n-6) and to a lesser extent 20:4(n-6) decreased. Incorporation of n-3 fatty acids increased the phosphatidylcholine/sphingomyelin ratio without changing the total phospholipid or free cholesterol content of the membrane. Fish oil feeding also caused a marked increase in the proportion of 24:1 in sphingomyelins, which occurred mainly at the expense of 18:0 and 24:0. New n-3 fatty acid-containing species appeared in the choline and ethanolamine glycerophospholipids, when compared to membrane lipids from lard-fed rats. Membranes from fish oil fed rats also had moderately higher levels of ether lipids. Few differences were seen between the membranes of the epididymal and perirenal adipocytes. It is concluded that dietary fish oils modify the lipid structure of rat adipocyte plasma membranes by increasing the ratio of phosphatidylcholine to sphingomyelin and by increasing the proportion of molecular species with polyunsaturated fatty acids, which would be anticipated to increase the fluidity of the lipid bilayer of adipocyte plasma membranes.

Oxidative modification enhances lipoprotein(a)-induced overproduction of plasminogen activator inhibitor-1 in cultured vascular endothelial cells

Elevated levels of plasma lipoprotein (a) [Lp(a)] have been considered as a strong risk factor for premature cardiovascular diseases. Plasminogen activator inhibitor-1 (PAI-1) is the major physiological inhibitor of plasminogen activators (PA). Increases in PAI-1 levels with or without a reduction in PA levels have been frequently found in coronary artery disease patients. The present paper examined the effects of oxidized Lp(a) on the production of PAI-1 in cultured human umbilical vein endothelial cells (HUVEC). Lp(a) and Lp(a)-free, low density lipoprotein (LDL) were prepared using lysine-Sepharose 4B affinity chromatography. Incubations with 10(-8) M levels of native Lp(a) moderately increased the levels of biologically active PAI-1 in post-culture medium of HUVEC compared to that with equimolar concentrations of native Lp(a)-free LDL. The release of PAI-1 induced by Lp(a) was enhanced by oxidative modification with copper ion. The stimulation of oxidized Lp(a) on PAI-1 production reached plateau in EC treated with 10-20 nM oxidized Lp(a) modified by microM CuSO4. Treatment with 0.2 micrograms/ml of actinomycin D significantly reduced native and oxidized Lp(a)-induced PAI-1 overproduction in EC. Increases in the steady state levels of PAI-1 mRNA were detected in native or oxidized Lp(a)-treated EC. The effect of Lp(a)-free oxidized LDL on PAI-1 production was significantly weaker than the equimolar amount of oxidized Lp(a) but stronger than that of native LDL. Treatments with oxidized Lp(a) increased cell-associated PAI-1 to a similar extent as that in native Lp(a)-treated EC. The results of the present paper demonstrate that oxidative modification enhances Lp(a)-induced PAI-1 production in vascular endothelial cells at RNA transcription level, which suggests that oxidization potentially amplifies the anti-fibrinolytic and thrombotic effect of Lp(a).

Effect of dietary vitamin E supplements on cholesteryl ester transfer activity in hamster adipose tissue

Increased concentration of cholesteryl ester transfer protein (CETP) in plasma favours a lipoprotein profile characterized by a reduced high density lipoprotein (HDL) cholesterol. Previous studies have demonstrated that a diet high in cholesterol and saturated fat (HCSF) is associated with elevated plasma CETP and increased release of cholesterol ester transfer activity (CETA) from hamster adipose tissue incubated in vitro. The present study investigated the effects of vitamin E (Vit.E) ingestion on plasma CETP activity and adipose tissue CETA in Syrian Golden hamsters. A regular diet supplemented by the addition of 1% cholesterol and 10% coconut oil (w/w) was associated with a time-dependent increase in plasma CETP activity and increased release of adipose CETA following incubation of fragments of perirenal adipose tissue. Vit.E ingestion (100 mg/kg body weight per day for 8 weeks) suppressed 85% of the increase of CETA released from cultured hamster adipose tissue and 70% of the increase of plasma CETP activity induced by the HCSF diet. Significant decreases in plasma total and LDL cholesterol and an increase in HDL cholesterol were found in hamsters receiving the HCSF diet plus Vit.E compared to the animals on the HCSF diet alone. In the hamsters on regular chow, Vit.E ingestion alone did not significantly alter adipose tissue CETA, plasma CETP activity or plasma lipoproteins. The results indicate that Vit.E prevents the HCSF diet-induced increase in plasma CETP activity, probably via a reduction of CETA secretion from hamster adipose tissue. This suggests that Vit.E supplementation may help to ameliorate the dyslipidemia caused by a HCSF diet through its inhibitory influence on CETP production in adipose tissue.

Analysis of cholesteryl ester transfer activity in adipose tissue

Transfer of cholesteryl ester (CE) between lipoproteins is mediated by a plasma glycoprotein called cholesteryl ester transfer protein (CETP) which plays an important role in reverse cholesterol transport between peripheral tissues and the liver. Adipose tissue is a major site of cholesterol storage and lipoprotein interactions. CE transfer activity in cultured adipose tissue from several species was analyzed by using a CE transfer assay in vitro. Significant amounts of CE transfer activity were detected in conditioned media of cultured adipose tissues from human, hamster and transgenic mice expressing CETP. The amount of CE transfer activity released from cultured adipose tissue varied among species and adipose regions. Monoclonal antibodies against human CETP (subclone TP2) inhibited CE transfer activity released from cultured adipose tissue of hamsters and CETP transgenic mice. CE transfer activity was also assayed in the aqueous phase of adipose tissue homogenates. Accumulation of CE transfer activity in the medium was associated with a reciprocal decrease in adipose tissue activity positively correlated to the amount of CETP mass in the conditioned medium and the aqueous phase of tissue homogenates from cultured hamster adipose tissue. The results of the present study indicate that the measurement of CE transfer activity in adipose tissue reliably characterizes the secretion and storage of CETP in adipose tissue.

Regulation of cholesteryl ester transfer activity in adipose tissue: comparison between hamster and rat species

The present study demonstrates cholesteryl ester transfer activity (CETA) in cultured hamster and rat adipose tissue. Cultured hamster and rat adipose tissue fragments released CETA into the conditioned medium, and this was associated with a reciprocal decrease in adipose tissue CETA. Regional variations in adipose CETA were observed. The levels of CETA released from cultured hamster and rat adipocytes were higher than those from adipose tissue fragments. In hamsters but not in rats, the secretion of CETA from cultured adipose tissue was increased by insulin and inhibited by EDTA in a dose-dependent fashion. Monoclonal antibodies against human cholesteryl ester transfer protein inhibited the CETA secreted from hamster adipose tissue but not that from rat adipose tissue. Fasting for 24 h and a high-cholesterol saturated fat-rich diet increased adipose CETA in hamsters and rats, and this was associated with an elevation of plasma CETA only in hamsters. This supports the view that, in hamsters, adipose CETA has in situ and intravascular functions, whereas in rats the role of adipose CETA is restricted to tissue-specific functions. Hamster cholesteryl ester transfer protein may differ from rat adipose-associated CETA in the structure of the active site and the regulatory mechanism for its secretion.

Thyroxine stimulates phosphatidylglycerolphosphate synthase activity in rat heart mitochondria

The effect of administration of exogenous thyroxine on mitochondrial phosphatidylglycerol content and biosynthesis was investigated in rat heart ventricles. Rats were treated for 5 consecutive days with thyroxine (250 mg/kg body weight) and on the sixth day after an overnight fast the mass of ventricular mitochondrial phosphatidylglycerol and cardiolipin content were determined. Saline-treated animals served as controls. Thyroxine treatment did not affect body weight but increased heart weight 30% compared with controls. In addition, the ratio of heart weight/body weight (x 1000) was increased from 0.69 in controls to 0.89 in thyroxine-treated rats consistent with this model. Thyroxine-treatment resulted in a 34% increase (P < 0.05) in phosphatidylglycerol and a 23% increase (P < 0.05) in cardiolipin content in ventricular mitochondrial fractions compared with controls. The mechanism for the increase in ventricular mitochondrial phosphatidylglycerol was investigated. Phosphatidic acid:cytidine-5'-triphosphate-1,2-diacylglycerol cytidylyltransferase and phosphatidylglycerolphosphate phosphatase activities were unaltered in the ventricular mitochondria of thyroxine-treated rats. In contrast, phosphatidylglycerolphosphate synthase activity was increased 3.5-fold (P < 0.05) in these mitochondrial fractions compared with controls. As a control for the effectiveness of thyroxine on mitochondria, cardiolipin synthase activity was determined. A 2.8-fold increase (P < 0.05) in cardiolipin synthase activity was observed in ventricular mitochondrial fractions of thyroxine-treated rats compared with controls. We postulate that thyroxine-treatment of rats produces an increase in the pool size of ventricular mitochondrial phosphatidylglycerol and that the mechanism is an increase in phosphatidylglycerolphosphate synthase activity.

Decrease in cardiac phosphatidylglycerol in streptozotocin-induced diabetic rats does not affect cardiolipin biosynthesis: evidence for distinct pools of phosphatidylglycerol in the heart

Biosynthesis of phosphatidylglycerol (PG) and cardiolipin (CL) were investigated in perfused hearts of diabetic rats 4 days or 28 days after streptozotocin injection. Sham-injected and insulin-treated diabetic rats were used as controls. In addition, another group of rats fasted for 54 h was examined. Isolated rat hearts from these groups were perfused for 30 min with [32P]P(i), and the radioactivity incorporated into PG and CL and their pool sizes were determined in heart ventricles. There was no difference in the amount of radioactivity incorporated into CL, PG or other phospholipids between all groups. In addition, the pool sizes of CL and other phospholipids were unaltered. However, a striking decrease in the pool size of PG was observed in both diabetic and fasted rats compared to sham- and insulin-treated controls at 4 days after streptozotocin injection. The decrease in PG mass in diabetic rats was rapid (within 24-48 h) and was localized to cardiac membranes. Diabetes did not affect the activity of the enzymes of PG and CL biosynthesis in the mitochondrial fraction, or phospholipase A activity in subcellular fractions prepared from rat heart homogenates. In addition, pulse-chase experiments confirmed that diabetes did not affect the rate of new PG or CL biosynthesis. Since radioactivity associated with PG was unaltered in continuous-pulse perfusion experiments, a calculated 1.8-fold increase in the specific radioactivity of cardiac PG was observed in the hearts of acute diabetic rats compared with controls. Since the radioactivity incorporated into PG and CL, and the rate of CL biosynthesis, were unaltered in diabetic-rat hearts compared with controls, new CL was probably synthesized from newly synthesized PG. We postulate the existence of distinct pools of PG in the heart, and that the pool of newly synthesized PG used for CL biosynthesis does not appear to mix immediately with the pre-existing pool of PG in the isolated intact rat heart.

Polymorphism and peripheral levels of apolipoprotein(a) in polygenic hypercholesterolemia and combined hyperlipidemia

This study demonstrates that peripheral apolipoprotein(a) [apo(a)] levels are higher in patients with polygenic hypercholesterolemia (PH) and combined hyperlipidemia (CH) than in controls. Levels of apo(a) inversely correlate with apo(a) isoform sizes. For a given apo(a) isoform, apo(a) levels are higher in PH and CH patients. Higher frequencies of smaller apo(a) isoforms were found in PH and CH patients than in controls, and in patients with coronary artery disease (CAD) or a family history of premature cardiovascular diseases than in patients without CAD or family history.

Effect of thrombin on release of plasminogen activator inhibitor-1 from cultured primate arterial smooth muscle cells

Plasminogen activator inhibitor-1 (PAI-1) is the major inhibitor for plasmin formation promoted by tissue and urokinase plasminogen activators. The present study demonstrates that thrombin increase PAI-1 antigen, biological activity, and gene expression in cultured baboon aortic smooth muscle cells (BASMC). Thrombin elevates PAI-1 antigen in conditioned medium of BASMC within 10 min of the treatment, with the peak increase after 30 min of the treatment. Overexpression of PAI-1 gene was detected in the cultures exposed to thrombin for at least 60 min. PAI activity in conditioned medium increased in the cultures treated with thrombin for at least 4 h. The thrombin-induced early increase of PAI-1 antigen (up to 30 min of the stimulation) was blocked by hirudin (a specific inhibitor of thrombin), mimicked by trypsin and not suppressed by cycloheximide (a protein synthesis inhibitor). The majority of metabolically labeled PAI-1 associated with BASMC was present in extracellular matrix. The level of extracellular matrix-associated PAI-1 was reduced 40% by 30 min of thrombin treatment. Our results suggest that thrombin not only increases PAI-1 transcription but also proteolytically cleaves PAI-1 from the extracellular matrix of vascular SMC. PAI-1 released by thrombin from the extracellular matrix may not alter PAI activity in extracellular fluid but may reduce the storage of PAI-1 in the extracellular matrix of vascular smooth muscle cells.

Alteration of lysophosphatidylcholine content in low density lipoprotein after oxidative modification: relationship to endothelium dependent relaxation

OBJECTIVE

The aim was to examine the formation of lipid peroxidation products and the alteration in phospholipid content in low density lipoprotein (LDL) after oxidative modification by CuSO4, and subsequently, to determine the ability of the modified LDL to impair endothelium dependent relaxation in rat aortic rings.

METHODS

Blood samples were obtained from normal human volunteers. LDL was prepared by sequential ultracentrifugation and it was oxidatively modified in the presence of 5 microM CuSO4. Lipid peroxidation products (thiobarbituric acid reactive substances, TBARS), and alterations in electrophoretic mobility and phospholipid content were determined in normal (native) and oxidised LDL. Endothelium dependent relaxation was produced by acetylcholine (10(-8)-10(-5) M) in phenylephrine precontracted rat aortic rings.

RESULTS

LDL incubated for 24 h with 5 microM CuSO4 at 20 degrees C and 37 degrees C with constant agitation displayed higher amounts of TBARS than the respective native LDL. While the amounts of TBARS in LDL modified at 20 degrees C and 37 degrees C were similar, the former condition resulted in statistically smaller changes of phospholipid contents. LDL with higher lysophosphatidylcholine content showed greater impairment of endothelium dependent relaxation in rat aortic rings than LDL with lower lysophosphatidylcholine content.

CONCLUSIONS

The raised lysophosphatidylcholine level in oxidatively modified LDL was related to the ability of the LDL to impair endothelium dependent relaxation. However, lipid peroxidation products assessed by TBARS did not relate to the phospholipid changes in LDL and therefore cannot be used to predict the vascular effects of LDL after oxidative modification.

A humanized CD18 antibody can block function without cell destruction

Leukocyte integrins are intimately involved in transient adherence of leukocytes to endothelium and to each other in the processes of extravasation and cell activation. In this study, seven mAb directed against human CD11a and two mAb directed against human CD18, the alpha- and beta-chains of the leukocyte functional Ag-1 molecule, respectively, were analyzed for their ability to inhibit several leukocyte functional Ag-1-mediated interactions. The best blocking mAb in these studies, a rat anti-human CD18, YFC51.1, was subsequently humanized by complementarily-determining region grafting, associated with human C regions and expressed. The humanized mAb was shown to maintain binding for human CD18. Even though the humanized mAb was an IgG1 isotype it still retained the functional blocking characteristics of the rat mAb while failing to mediate cell killing. The IgG1 mAb was unable to bind human Clq and could block but did not mediate antibody-dependent cellular cytotoxicity.