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Biomedical subjects

M Roth

Publications and source records attributed to M Roth.

At least 109 records · Page 6Linked to original sources
PubMed1997

Reoperations after dacron patch aortoplasty with heparinized femoro-femoral bypass.

Dacron patch aortoplasty used to be a standard therapy in some surgical units. Occurrence of aneurysm formation after this procedure is well known. The incidence of aneurysms is reported to be 0-35% with a high risk of lethal rupture. We report three cases of aneurysm repair of the descending thoracic aorta after dacron patch aortoplasty using femoro-femoral extracorporeal system. Heparin-coated system was used primarily to prevent ischemic spinal cord injury through hypotension of the distal aorta and secondarily to reduce the risk of intraoperative hemorrhage.

Adult↗
PubMed1997

Effects of 1- and 6-month spaceflight on bone mass and biochemistry in two humans.

The bone mineral density and the biochemical parameters exploring bone cell activities were analyzed in two cosmonauts who spent 1 and 6 months, respectively, in the Russian MIR station. Measurements were performed before the flight, after the flight, and after a recovery period. At the end of the first month, peripheral QCT measurements indicated a slight decrease of trabecular bone mass in the distal tibial metaphysis. However, after 6 months of spaceflight, a more marked loss of trabecular and cortical bones was observed in the tibia, and was still significant after 6 month recovery in the trabecular compartment, whereas a decrease was no longer observed in the cortical envelope. No change was observed in either compartment of the distal radius at any time. Ultrasound BUA of the calcaneus was greatly reduced by the first month, followed by a more dramatic decrease after month 6. Ultrasound SOS detected no change. Parameters reflecting bone formation activity appeared to be depressed after both missions. In contrast, no dramatic change in resorption parameters was observed, except for a trend toward an increase in pyridinoline. In conclusion, the lower weight-bearing bones appeared more sensitive than the upper ones in terms of spaceflight-induced bone loss. This probably explained the absence of marked systemic biochemical data changes. This study further suggests that recovery in the tibial trabecular compartment 6 months after landing was not completed after a 6 month mission.

Adult↗
PubMed1997

A successful, preventive-oriented village health worker program in Hebron, the West Bank, 1985-1996.

Village health rooms (VHRs) were established in villages with no on-site health facilities in the Hebron District of the West Bank, beginning in 1985. By 1991, the program served a total population of 40,000 in 49 VHRs and by the end of 1996 covered 69 villages in Hebron and 20 in other districts that were previously served by visiting vaccination teams and nearby clinics. The VHRs provide close contact with the population of mothers for well child and pregnancy care, health education and provide visiting doctor/nurse teams for backup services and supervision. Data on coverage, utilization, costs, and outcome measures are presented. The program is accepted and grows despite adverse social and political conditions.

Community Health Services↗
PubMed1997

Effect of a novel 5-lipoxygenase activating protein inhibitor, BAYx 1005, on asthma induced by cold dry air.

BACKGROUND: Leukotrienes have been implicated in the mediation of airway obstruction induced by hyperventilation of cold dry air in asthmatic subjects. The effect of a novel inhibitor of 5-lipoxygenase activating protein, BAYx 1005, on the bronchospastic response to cold dry air hyperventilation was investigated in asthmatic patients. METHODS: After a screening cold dry air hyperventilation challenge to document cold air responsiveness, 16 asthmatic subjects (baseline forced expiratory volume in one second (FEV1) > 60% of predicted) underwent cold air challenge three hours after receiving 750 mg of BAYx 1005 or placebo using a randomised, double blind, crossover design. Leukotriene synthesis inhibition was estimated by measuring the concentration of leukotriene B4 in whole blood stimulated with calcium ionophore A21387. RESULTS: Treatment with BAYx 1005 produced a 34% (95% CI 11 to 63) increase in the amount of cold air minute ventilation required for a 10% decrease in FEV1 (PD10VE) compared with placebo (mean (SE) 37.6 (1.12) 1/min compared with 28.0 (1.13) 1/min, p < 0.006). The PD20VE increased 19% (95% CI 8 to 31) after treatment with BAYx 1005 compared with placebo (57.3(1.10)1/min versus 48.1 (1.10) 1/min, p < 0.002). Treatment with BAYx 1005 produced a 15.4% decrease in ionophore-stimulated LTB4 production, while treatment with placebo produced a 7.1% increase in ex vivo LTB4 (p < 0.02). CONCLUSIONS: Treatment with BAYx 1005, a novel inhibitor of leukotriene synthesis, produced a significant blunting of cold dry air responsiveness consistent with the hypothesis that leukotrienes mediate part of the bronchoconstriction induced by hyperventilation of cold dry air.

Adolescent↗
PubMed1997

Procoagulant activity of purified protein derivative-stimulated pleural effusion mononuclear cells in tuberculous pleurisy.

Mononuclear cells (MNC) generate cell-bound procoagulant activity (PCA) which shortens recalcification time after incubation with an antigen to which the donor has been sensitized. PCA has been demonstrated in various lung diseases, including exudative pleural effusions. To determine the value of measuring cell-bound PCA in the diagnosis of tuberculous pleural effusions we examined pleural effusion MNC of patients with tuberculosis (n = 19), congestive heart failure (n = 7), and carcinoma (n = 7). MNC were isolated, incubated in 0 or 10 micrograms/ml purified protein derivative (PPD) for 15 min and for 20 h, and recalcification time determined. Incubation with thromboplastin was used as control. The recalcification times in serum incubated for 15 min varied within a wide range, the mean values were longest for tuberculous effusion MNC, incubation for 20 h increased variation. Incubation of cells for 15 min with thromboplastin led to a decrease of mean recalcification time in tuberculous (p < 0.001) and heart failure (p < 0.05), and with no significance in carcinomatous effusions. Incubation with PPD led to decrease of recalcification time which was not significant. Comparisons of the mean relative recalcification times after PPD incubation showed that tuberculosis differed from lung cancer (p < 0.001), lung cancer from heart failure (p < 0.05), but not heart failure from tuberculosis. We conclude from our study that pleural effusion MNC express spontaneous PCA in vitro which is strongest in carcinomatous pleural effusions. Incubation of MNC with thromboplastin and less discernable with PPD leads to an increase in PCA which is more pronounced in tuberculous pleural effusions. However, due to substantial intersubject variability and overlap between the study groups, this test does not allow reliable differentiation of tuberculous from other MNC rich pleural effusions.

Blood Coagulation↗
PubMed1997

MMP and TIMP expression pattern in pleural effusions of different origins.

The matrix metalloproteinases (MMP) are proteolytic enzymes that are essentially involved in the turnover of the extracellular matrix (ECM). Their activity is counterbalanced by specific antagonists, the tissue inhibitors of metalloproteinases (TIMP). In this study, we sought to analyze the expression of MMP and TIMP isoforms in pleural effusions from 88 patients. We compared MMP and TIMP isoform expression in transudates (n = 21) and exudates (n = 67), the latter divided into exudates of paraneoplastic (n = 46) or parainfectious (n = 21) origin. Zymographic and Western blot analyses revealed constant expression of interstitial collagenase (MMP-1), gelatinase-A (MMP-2), and TIMP-1 in all 88 samples. In contrast, analyses of gelatinase-B (MMP-9) demonstrated a specific expression pattern, with high expression in exudates and lack of expression in transudates. Neutrophil collagenase (MMP-8) was detected in trace amounts, and correlated with the number of neutrophils in the effusion. Low levels of TIMP-2 were detected only in exudates and not in transudates. Quantitative analysis of the expression ratio of gelatinase-B to gelatinase-A revealed statistically significant differences between effusions of different origin. The ratio was highest in exudates of paraneoplastic origin and lowest in transudates. Our data thus suggest that interstitial collagenase, gelatinase-A, and TIMP-1 play a role in homeostasis of the pleural space in vivo as constitutively expressed proteins, whereas gelatinase-B and TIMP-2 expression are induced in specific disease states. These observations contribute to the understanding of the pathophysiology of pleural effusions, and may help to characterize and possibly distinguish effusions of different origin.

Adult↗
PubMed1997

Induction of vascular endothelial growth factor by platelet-activating factor and platelet-derived growth factor is downregulated by corticosteroids.

Vascular endothelial growth factor (VEGF) is a potent peptide growth factor specific for vascular endothelial cells, which promotes neovascularization and increases vascular permeability in vivo. Enhanced microvascular permeability and edema are common characteristics of inflammatory and neoplastic disorders. Two proinflammatory mediators, platelet-activating factor (PAF) and platelet-derived growth factor (PDGF), are known to contribute to cellular damage and tissue remodeling in a number of lung diseases. To determine whether PAF or PDGF induce VEGF gene expression in primary cultures of human pulmonary fibroblasts and pulmonary vascular smooth-muscle cells (VSMCs), we performed Northern-blot analysis and enzyme-linked immunosorbent assays (EIA). PAF and all three isoforms of PDGF (PDGF-AA, -AB, and -BB) increased VEGF mRNA in a time- and dose-dependent manner. While PAF was shown to increase VEGF mRNA at picomolar concentrations, all PDGF isoforms were effective in inducing VEGF mRNA at nanomolar concentrations. The transcriptional activation was accompanied by increased levels of VEGF protein as determined by EIA in culture medium. These results indicate that VEGF gene expression in VSMCs and fibroblasts is mediated by PAF and/or PDGF isoforms. In a paracrine mode of action, secreted VEGF may then lead to altered endothelial cell functions and vascular hyperpermeability. In the presence of the corticosteroids cortisone, hydrocortisone, dexamethasone, or prednisolone at nanomolar concentrations, this stimulus-dependent transcription of VEGF was abolished. The inhibitory effect of corticosteroids on VEGF expression could explain the clinically well-known antiedematous potency of corticosteroids on a molecular level.

Adrenal Cortex Hormones↗
PubMed1996

Selective inhibition of Alzheimer disease-like tau aggregation by phenothiazines.

In Alzheimer disease (AD) the microtubule-associated protein tau is redistributed exponentially into paired helical filaments (PHFs) forming neurofibrillary tangles, which correlate with pyramidal cell destruction and dementia. Amorphous neuronal deposits and PHFs in AD are characterized by aggregation through the repeat domain and C-terminal truncation at Glu-391 by endogenous proteases. We show that a similar proteolytically stable complex can be generated in vitro following the self-aggregation of tau protein through a high-affinity binding site in the repeat domain. Once started, tau capture can be propagated by seeding the further accumulation of truncated tau in the presence of proteases. We have identified a nonneuroleptic phenothiazine previously used in man (methylene blue, MB), which reverses the proteolytic stability of protease-resistant PHFs by blocking the tau-tau binding interaction through the repeat domain. Although MB is inhibitory at a higher concentration than may be achieved clinically, the tau-tau binding assay was used to identify desmethyl derivatives of MB that have Ki values in the nanomolar range. Neuroleptic phenothiazines are inactive. Tau aggregation inhibitors do not affect the tau-tubulin interaction, which also occurs through the repeat domain. Our findings demonstrate that biologically selective pharmaceutical agents could be developed to facilitate the proteolytic degradation of tau aggregates and prevent the further propagation of tau capture in AD.

Alzheimer Disease↗
PubMed1996

Platelet-activating factor exerts mitogenic activity and stimulates expression of interleukin 6 and interleukin 8 in human lung fibroblasts via binding to its functional receptor.

Platelet-activating factor (PAF) is a potent proinflammatory phospholipid mediator of the lung. In this study, we demonstrate that PAF receptor mRNA and protein is expressed by human lung fibroblasts. Interaction of PAF with its specific receptor resulted in increases of tyrosine phosphorylation of several intracellular proteins, indicating that the PAF-receptor might be functionally active. PAF-induced transcription of protooncogenes c-fos and c-jun as well as of interleukin (IL)-6 and IL-8 genes in human fibroblasts. Transcription of the interleukins was followed by secretion of the respective proteins. Moreover, PAF enhanced proliferation of fibroblasts in a concentration-dependent manner. Using signaling inhibitors, we demonstrate that PAF-induced transcription of the c-fos, IL-6, and IL-8 genes, as well as proliferation, require activation of pertussis toxin-sensitive G proteins, tyrosine kinases, and protein kinase C (PKC). In contrast, transcription of c-jun was blocked by pertussis toxin, but not by inhibitors for tyrosine kinases or PKC. These data suggest that PAF stimulates distinct signaling pathways in human lung fibroblasts. In addition, the activation of human fibroblasts by PAF leads to enhanced proliferation and to the expression of proinflammatory cytokines, which may contribute to the pathophysiological changes in pulmonary inflammation.

Cells, Cultured↗
PubMed1996

Ca2+ channel blockers modulate metabolism of collagens within the extracellular matrix.

The extracellular matrix (ECM) is an intricate network composed of an array of macromolecules capable of regulating the functional responsiveness of cells. Its composition greatly varies among different types of tissue, and dysregulation of its metabolism may contribute to vascular remodeling during the pathogenesis of various diseases, including atherosclerosis. In view of their antiatherosclerotic effects, the role of Ca2+ channel blockers in the metabolism of ECM was examined. Nanomolar concentrations of the five Ca2+ channel blockers amlodipine, felodipine, manidipine, verapamil, or diltiazem significantly decreased both the constitutive and platelet-derived growth factor BB-dependent collagen deposition in the ECM formed by human vascular smooth muscle cells and fibroblasts. The drugs inhibited the expression of fibrillar collagens type I and III and of basement membrane type IV collagen. Furthermore, Ca2+ channel blockers specifically increased the proteolytic activity of the 72-kDa type IV collagenase as shown by gelatin zymography and inhibited the transcription of tissue inhibitor of metalloproteinases-2.

Amlodipine↗
PubMed1996

Possible involvement of primary motor cortex in mentally simulated movement: a functional magnetic resonance imaging study.

The role of the primary motor cortex (M1) during mental simulation of movement is open to debate. In the present study, functional magnetic resonance imaging (fMRI) signals were measured in normal right-handed subjects during actual and mental execution of a finger-to-thumb opposition task with either the right or the left hand. There were no significant differences between the two hands with either execution or simulation. A significant involvement of contralateral M1 (30% of the activity found during execution) was detected in four of six subjects. Premotor cortex (PM) and the rostral part of the posterior SMA were activated bilaterally during motor imagery. These findings support the hypothesis that motor imagery involves virtually all stages of motor control.

Adult↗
PubMed1996

Diagnostic transaortic cardioscopy of the left ventricle.

Preoperative diagnosis of pathologic intracardiac structures by noninvasive techniques is sometimes difficult or even impossible. In these cases a heart operation is required with opening of one or more cardiac chambers. We demonstrate direct visualization of the left ventricular cavity by transaortic cardioscopy in a patient with a pathologic intraventricular structure. With this technique we could avoid ventriculotomy.

Cardiac Surgical Procedures↗