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Biomedical subjects

A Szabo

Publications and source records attributed to A Szabo.

At least 37 records · Page 2Linked to original sources
PubMed2001

Chlamydia pneumoniae in atherosclerotic middle cerebral artery.

BACKGROUND AND PURPOSE: Atherosclerotic middle cerebral arteries are frequent sites of thrombosis, leading to stroke. Previous studies have suggested a role for Chlamydia pneumoniae in the pathogenesis of atherosclerosis. However, the presence of this pathogen in atherosclerotic middle cerebral arteries has heretofore not been documented. In the present study, we analyzed atheromatous plaques from middle cerebral arteries for the presence of C pneumoniae. METHODS: Atherosclerotic middle cerebral arteries from 15 cadavers who died of natural causes and corresponding nonatherosclerotic arteries from 4 otherwise healthy trauma victims were examined. Assays for C pneumoniae DNA were carried out by nested polymerase chain reaction (nPCR) specific for the C pneumoniae ompA gene. The presence of the bacterium was assessed by transmission electron microscopy. RESULTS: Five of the 15 atherosclerotic arterial samples and none of the control tissues were positive for C pneumoniae by nPCR. Particles similar in morphology and size to C pneumoniae elementary bodies were detected by transmission electron microscopy in 4 of the 5 nPCR-positive atherosclerotic samples. CONCLUSIONS: The demonstration of C pneumoniae in atherosclerotic middle cerebral arteries is consistent with the hypothesis that this bacterium is involved in acute and chronic cerebrovascular diseases.

Adult↗
PubMed2000

[Chronic renal allograft rejection. Part 2. Therapeutic possibilities] .

Chronic rejection represents an important cause of renal allograft loss in the long term follow up. New insights into etiopathogenesis of the chronic rejection offer possibilities for experimental therapy. Novel immunosuppressants, such as mycophenolic acid, tacrolimus or rapamycin as well as lipid lowering drugs, angiotensin-converting enzyme inhibitors or AT-1 receptor blockers, may reduce of effects the risk factors on the progression of chronic rejection. In the future, gene therapy may offer additional possibilities to prevent chronic rejection. This review deals with possibilities of prevention of the chronic renal allograft rejection based on experimental evidences and current therapeutic concepts and puts these options into a rational perspective.

Chronic Disease↗
PubMed2000

Lipopolysaccharide pretreatment protects from renal ischemia/reperfusion injury : possible connection to an interleukin-6-dependent pathway.

In vivo administration of low doses of lipopolysaccharide (LPS) to rodents can protect these animals from subsequently administrated, usually lethal doses of endotoxin or LPS. In this study we tested the effects of LPS pretreatment on ischemia/reperfusion injury in the kidney. Male C57/B1 mice were pretreated with different doses of LPS or phosphate-buffered saline on days -4 and -3. The right kidney was removed, and the vessels of the left kidney were clamped for 30 or 45 minutes on day 0. Creatinine levels and survival of animals were monitored. To test the involvement of cytokines, additional animals were harvested before ("time 0") and 15 minutes, 1, 2, 8, and 16 hours after reperfusion for histology, immunohistochemistry, terminal deoxynucleotidyltransferase-mediated UTP end-labeling assay, and reverse transcriptase-polymerase chain reaction analysis (including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6, inducible nitric oxide synthase (iNOS), and interferon (IFN)-gamma messenger RNA (mRNA)). In controls, renal ischemia of 30 minutes was nonlethal, whereas 73% of the animals died within 48 +/- 18 hours, after 45 minutes of ischemia. All different doses of LPS protected the animals from lethal renal ischemia/reperfusion injury. Starting at similar levels, serum creatinine increased significantly in controls but not in LPS-pretreated animals over time. As early as 2 hours after reperfusion, tubular cell damage was significantly more pronounced in controls than in LPS-treated mice. In controls, tubules deteriorated progressively until 8 hours of reperfusion. At this time, more than 50% of tubular cells were destroyed. This destruction was accompanied by a pronounced leukocytic infiltration, predominantly by macrophages. In contrast, LPS pretreatment prevented the destruction of kidney tissue and infiltration by leukocytes. The terminal deoxynucleotidyltransferase-mediated UTP end-labeling assay revealed significantly more apoptotic cells in controls compared with LPS-pretreated animals. IL-1, IFN-gamma, and iNOS mRNA expression did not differ between the groups throughout the time points examined. However, the expression of TNF-alpha mRNA was significantly increased at 2 hours and IL-6 mRNA was significantly down-regulated before ischemia and shortly after reperfusion in the LPS-pretreated kidneys. Therefore, we found that sublethal doses of LPS induced cross-tolerance to renal ischemia/reperfusion injury. Our data suggest that increased TNF-alpha and reduced IL-6 mRNA expression might be responsible. However, more studies are needed to decipher the exact mechanism.

Animals↗
PubMed2000

Effect of angiotensin-converting enzyme inhibition on growth factor mRNA in chronic renal allograft rejection in the rat.

BACKGROUND: Despite considerable progress in immunosuppression, the incidence of chronic renal allograft rejection has not decreased. Recent studies have revealed that angiotensin-converting enzyme (ACE) inhibition ameliorates graft arteriosclerosis, glomerulosclerosis, and tubular atrophy. Moreover, it decreases systemic and glomerular capillary hydrostatic pressure in a rat kidney allograft model. We evaluated the effects of the ACE inhibitor enalapril on cytokine and growth factor expression in chronically rejecting rat kidney allografts. METHODS: Kidneys of Fisher (F344) rats were orthotopically transplanted into Lewis (Lew) rats. To prevent acute rejection, cyclosporine A (1.5 mg/kg/day) was given to all recipients during the first 10 days after transplantation. Enalapril (60 mg/L) or vehicle was added to the drinking water 10 days after transplantation. Animals were harvested 20 weeks after transplantation for histologic and immunohistologic studies, as well as for evaluation of cytokine and growth factor mRNA by semiquantitative polymerase chain reaction. RESULTS: Controls developed severe signs of chronic rejection, such as glomerular and vascular lesions, associated with a large number of infiltrating leukocytes. Enalapril-treated animals developed less proteinuria and other signs of chronic rejection. The mRNA levels of transforming growth factor-beta 1 (TGF-beta 1), platelet-derived growth factor A and B chain (PDGF A and B), insulin-like growth factor-I (IGF-I), interleukin-1 (IL-1), and monocyte chemoattractant protein-1 (MCP-1) were significantly reduced in the enalapril group and were most pronounced for IL-1 and PDGF A. In addition, we found an increased level of renal angiotensinogen mRNA after treatment with enalapril. CONCLUSIONS: Treatment with enalapril attenuated the development of proteinuria, ameliorated morphological damage, decreased leukocyte infiltration, and prevented a rise in renal mRNA levels of growth factors and cytokines in kidney grafts in a rat model of chronic renal allograft rejection.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Temporal patterning of competitive emotions: a critical review.

An interactional model of stress that integrates current research on competitive affects and emphasizes the temporal dimensions of the stress process is forwarded. The literature reveals that the study of athletes' affective responses to competition has been narrowly focused on pre-competitive anxiety. Equivocal findings on temporal patterning of competitive anxiety suggest that a fundamental change in the empirical approach is needed because the current conceptualization of anxiety and other complex emotions is imprecise. The analysis of secondary emotions as patterns of discrete basic emotions, as suggested by differential emotions theorists, is proposed for consideration in future research. In this view, competitive anxiety is considered as a set of patterns of emotions rather than a unitary affect. The adoption of this approach could result in better operationalization of competitive anxiety as well as other secondary performance-related emotions. We propose that research on competitive affects should follow two parallel lines. The first should focus on the description of complex emotional states that reflect the idiosyncratic emotional experience and vocabulary of the athlete. The second should examine the sets of basic emotions experienced throughout competition, and focus on individual differences and factors determining those differences. The integration of the two approaches could lead to a better understanding of whether, how and why individuals differ in the interpretation of specific secondary emotions and their effect on performance. Moreover, it would permit the analysis of intra-individual variations in labelling secondary emotions with respect to different competitive contexts and temporal aspects.

Anxiety↗
PubMed2000

Entropic barriers, transition states, funnels, and exponential protein folding kinetics: a simple model.

This paper presents an analytically tractable model that captures the most elementary aspect of the protein folding problem, namely that both the energy and the entropy decrease as a protein folds. In this model, the system diffuses within a sphere in the presence of an attractive spherically symmetric potential. The native state is represented by a small sphere in the center, and the remaining space is identified with unfolded states. The folding temperature, the time-dependence of the populations, and the relaxation rate are calculated, and the folding dynamics is analyzed for both golf-course and funnel-like energy landscapes. This simple model allows us to illustrate a surprising number of concepts including entropic barriers, transition states, funnels, and the origin of single exponential relaxation kinetics.

Algorithms↗
PubMed2000

Evaluation of seprafilm and amniotic membrane as adhesion prophylaxis in mesh repair of abdominal wall hernia in rats.

INTRODUCTION: Adhesion formation following abdominal wall hernia repair with prosthetic mesh may lead to intestinal obstruction and enterocutaneous fistula. Physical barriers, namely, human amniotic membrane (HAM) or Seprafilm (Genzyme, Cambridge, Mass., USA), a bio-absorbable, translucent membrane composed of carboxymethylcellulose and hyaluronic acid, have been reported to prevent postsurgical intra-abdominal adhesions. OBJECTIVE: Evaluating the effect of HAM and Seprafilm in preventing adhesion formation in the rat model of ventral hernia repair with polypropylene mesh (PPM). MATERIAL AND METHODS: Sixty female Sprague-Dawley rats were divided into three groups. A full-thickness abdominal wall defect was created in each animal. Control animals had the PPM sutured into the defect, whereas in the other two groups, either HAM or Seprafilm were laid over the abdominal viscera before the repair with PPM. Half of the animals in each group were sacrificed on the 21st postoperative day. The remaining rats of the same group were re-operated on the 42nd day for investigation and measurement of the adhesion area in relation to the graft area. RESULTS: Direct mesh repair showed 52.8 and 56% area adhesion formation 3 and 6 weeks postoperatively, respectively. The HAM barrier covered with mesh repair demonstrated 0 and 0.96% area adhesion formation, and the Seprafilm-covered mesh repair showed 0 and 0% area adhesion formation 3 and 6 weeks postoperatively, respectively. Uncovered mesh showed a significantly larger adhesion area than both covered mesh (p = 0.001 and 0.001). Both HAM and Seprafilm were equally effective in preventing postoperative adhesions. CONCLUSIONS: HAM and Seprafilm proved to be an effective antiadhesive barrier in PPM repair of abdominal wall hernia.

Abdomen↗
PubMed2000

Public health reforms and development of health service in the Dakovo sub-district and administrative county in the period 1850-1899.

In the long-lasting struggle for national identity and modernization of Croatia, the Parliament of the Kingdom of Croatia and Slavonia has passed many laws and regulations from 1874 on, affecting thus the health care and the development of the public health system. The aim of those laws was to establish and achieve the same level of public health care that had already been instituted in some other countries of the Austro-Hungarian Empire. In order to clarify the consequences of these reforms for the development of the health care system on the county and district levels of Slavonia, we collected data on the town of Dakovo as a market center, home of the diocese, and seat of the sub-district and administrative county. The data were divided into several categories in order to examine (1) the reorganization of health care in the Kingdom of Croatia and Slavonia from 1848 to 1894; (2) the development of health care in the Dakovo sub-district and Dakovo administrative county; (3) number, structure, and distribution of medical practitioners from 1807 to 1899; (4) hospitals from 1859 to 1900; and (5) selected indicators of health and living condition and health needs of the county inhabitants in the period 1850-1900. The analysis of historical material showed that new regulations of health care initiated the process of "medicalization" that was understood as a part of European modernization in the field of state medicine and health care administration. It brought more accurate knowledge of the main causes of illnesses, deaths and disabilities but did not significantly improve health and health conditions in the Dakovo County at the entrance of the 20th century.

Croatia↗
PubMed2000

Down-regulation of benzodiazepine binding to alpha 5 subunit-containing gamma-aminobutyric Acid(A) receptors in tolerant rat brain indicates particular involvement of the hippocampal CA1 region.

Chronic benzodiazepine treatment can produce tolerance and changes in gamma-aminobutyric acid (GABA)(A) receptors. To study the effect of treatment on a selected population of receptors, assays were performed using [(3)H]RY-80, which is selective for GABA(A) receptors with an alpha 5 subunit. Rats were given a flurazepam treatment known to produce tolerance and down-regulation of benzodiazepine binding, or a diazepam treatment shown to produce tolerance but not receptor down-regulation. Quantitative receptor autoradiography using sagittal brain sections bound with [(3)H]RY-80 showed binding in areas known to express alpha 5 mRNA. Brains from flurazepam-treated rats showed significantly decreased 1 nM [(3)H]RY-80 binding in hippocampal formation (e.g., 32% decrease in CA1) and superior colliculus, but not other areas. Using 5 nM [(3)H]RY-80 showed similar decreases in hippocampus. A corresponding 29% decrease in B(max) but no change in K(d) was found with a filtration binding assay using hippocampal homogenates. Down-regulation of [(3)H]RY-80 binding had returned to control by 2 days after withdrawing flurazepam treatment. The magnitude of down-regulation of [(3)H]RY-80 binding suggested that GABA(A) receptors with an alpha 5 subunit may play a prominent role in the adaptive responses associated with benzodiazepine tolerance. Chronic diazepam treatment also resulted in decreased [(3)H]RY-80 binding. However, the regional selectivity was even more pronounced than in flurazepam-treated rats, and only the hippocampal CA1 region showed decreased binding (27%). This localized down-regulation persisted for several days after the end of diazepam treatment. These data indicate that synapses in the hippocampal CA1 region are particularly involved in the adaptive response to chronic benzodiazepine treatments.

Alkynes↗
PubMed1999

In vivo migration of lymphocytes in chronically rejecting rat kidney allografts.

Histological analyses have identified lymphocytes and macrophages as the predominant leukocyte populations that infiltrate organs undergoing chronic rejection. In order to define the time frame of this infiltration, we investigated the in vivo migration pattern of lymphocytes in a well-established rat model of chronic kidney allograft rejection. F344 kidneys were orthotopically transplanted into bilaterally nephrectomized Lewis rats. Recipients were treated with cyclosporin A (1.5 mg/kg/per day) for the first 10 days. After anti-CD18 or vehicle pretreatment, peripheral blood lymphocytes obtained from naive Lewis rats and labeled with 3H-uridine were injected into transplanted rats 12 and 16 weeks after transplantation. Organs were harvested 4, 8, and 12 h thereafter. After 12 weeks, proteinuria developed, accompanied by all signs of chronic rejection including glomerular sclerosis. Labeled lymphocytes rapidly infiltrated grafted kidneys 4 h after injection. Even more lymphocytes had accumulated in the grafts 12 h after injection. After 16 weeks, few lymphocytes had emigrated into the graft at 4 h, while infiltration was most pronounced by 12 h. Pretreatment with anti-CD18 inhibited the influx of lymphocytes. There was no difference between the patterns of lymphocytes derived from naive and transplanted rats. Our results emphasize the importance of endothelial cells in chronically rejecting kidneys for the control of leukocyte influx. Beta2-integrins may play a central role in determining the transendothelial migration during this process.

Animals↗
PubMed1999

Use of endoscopic trocar-cannula for chest drain insertion in trauma patients and others.

BACKGROUND: The insertion of a chest drain into the pleural space is a common procedure used for treatment in various intrathoracic abnormalities. Recently, a new technique for chest-tube insertion for pleural cavity drainage, using the disposable endoscopic trocar-cannula, was described for the treatment of some pathologic conditions. METHODS: In a prospective study, we used this technique in the treatment of patients with chest trauma, spontaneous and iatrogenic pneumothorax, and various kinds of pleural effusion. RESULTS: One hundred twelve patients were treated by using the endoscopic trocar-cannula for tube insertion into the pleural cavity. Among them, 39 patients were treated after blunt and penetrating chest trauma. Most cannulae were of 10 to 11 mm in diameter, which enabled the insertion of large-bore drain tubes. In five trauma patients, chest-tube insertion was done successfully without antecedent chest x-ray films. The complication rate was 0.89% for intrapulmonary positioning of a chest tube in a patient who had previous ipsilateral thoracic surgery. CONCLUSION: The use of endoscopic trocar-cannulae for chest-tube insertion is a safe, simple, and effective technique for management of trauma and other diverse intrathoracic abnormalities. Its use outside the hospital should be further studied.

Adolescent↗
PubMed1999

The effects of slow- and fast-rhythm classical music on progressive cycling to voluntary physical exhaustion.

BACKGROUND: To investigate, based on the parallel information processing model and arousal hypothesis, whether musical tempo and its manipulation during exercise affect the maximal workload (watts) achieved during progressive cycling. METHODS DESIGN: repeated measures experiment that involved one control and four treatment conditions. SETTINGS: the experiment was performed in a controlled laboratory environment. PARTICIPANTS: twenty-four male and female volunteers, recruited from among a University population, were tested. INTERVENTION: the data collection proceeded in five counterbalanced test-sessions that included control (C), slow music (SM), fast music (FM) slow to fast music (SFM) and fast to slow music (FSM) interventions. In the last two conditions, musical tempo was changed when the participant's maximal HR reserve has reached 70%. In all test-sessions, participants started to cycle at 50 watts and then the workload was increased in increments of 25 watts every minute until self-declared exhaustion. Maximal ergometer cycling was defined as the workload at the last completed minute of exercise. MEASURES: workload, HR, and postexperimental ratings of test-session preferences were the dependent measures. RESULTS: Significantly higher workload was accomplished in the SFM condition. No between-session differences were seen in HR. The results also yielded significantly better "efficiency", in terms of workload/HR reserve ratio, in the SFM session. PARTICIPANTS preferred the FM and SFM sessions more than the other sessions. CONCLUSIONS: Switching to FM during progressive exercise results in the accomplishment of more work without proportional changes in HR. These effects may be due to distraction from fatigue and are, apparently, dependent on the attention capturing strength of the distracting stimulus.

Adult↗
PubMed1998

Electrostatic enhancement of diffusion-controlled protein-protein association: comparison of theory and experiment on barnase and barstar.

The electrostatic enhancement of the association rate of barnase and barstar is calculated using a transition-state theory like expression and atomic-detail modeling of the protein molecules. This expression predicts that the rate enhancement is simply the average Boltzmann factor in the region of configurational space where association occurs instantaneously in the diffusion-controlled limit. Based on experimental evidence, this "transition state" is defined by configurations in which, relative to the stereospecifically bound complex, the two proteins are shifted apart by approximately 8 A (so a layer of water can be accommodated in the interface) and the two binding surfaces are rotated away by 0 degrees to 3 degrees. The values of the average Boltzmann factor, calculated by solving the Poisson-Boltzmann equation, for the wild-type complex and 16 complexes with single mutations are found to correlate well with experimental results for the electrostatic rate enhancement. The predicted rate enhancement is found to be somewhat insensitive to the precise definition of the transition state, due to the long-range nature of electrostatic interactions. The experimental ionic strength dependence of the rate enhancement is also reasonably reproduced.

Bacterial Proteins↗
PubMed1998

Distinct prevalence of antibodies to the E2 protein of GB virus C/hepatitis G virus in different parts of the world.

Since the identification of the new human virus, GB virus C (GBV-C)/hepatitis G-virus (HGV), in 1995/1996, reverse transcription polymerase chain reaction remained the sole available diagnostic tool for GBV-C/HGV infection. Recently, a serologic test based on the detection of antibodies to the putative envelope protein 2 (anti-E2) has been introduced. We used this assay for a seroepidemiological survey including 3,314 healthy individuals from different parts of the world, 123 patients from Germany who were suspected to have an increased risk of acquiring GBV-C/HGV infection, 128 multiple organ donors, and 90 GBV-C/HGV RNA positive persons. In European countries, anti-E2 seropositivity ranged from 10.9% (Germany) to 15.3% (Austria). In South Africa (20.3%) and Brazil (19.5%), even higher anti-E2 prevalence rates were recorded. In Asian countries like Bhutan (3.9%), Malaysia (6.3%), and the Philippines (2.7%), anti-E2 positivity was significantly lower. GBV-C/HGV anti-E2 prevalence in potential "risk groups," i.e., patients on hemodialysis and renal transplant recipients, did not vary significantly from anti-E2 seroprevalence in German blood donors. Anti-E2 and GBV-C/HGV RNA were found to be mutually exclusive, confirming the notion that anti-E2 has to be considered as a marker of past infection.

Antibodies, Viral↗
PubMed1998

Hypertension accelerates the pace of chronic graft dysfunction in the rat.

In this study we compared the effects of hypertension on chronic rejection in a rat model of renal transplantation utilizing genetically normotensive (BBOK) and spontaneously hypertensive rats (SHR). SHR received either a BBOK (BBOK-->SHR) or an SHR (SHR-->SHR) kidney; normotensive isografts served as controls. Before transplantation, SHR recipients were treated with hydralazine (50 mg/kg per day). To prevent acute rejection, an anti-CD4 antibody (3 mg/kg per day for 3 weeks) in combination with cyclosporin A (3 mg/kg per day for 1 week) was given to all groups. Six weeks after transplantation, blood pressure was measured, and the kidneys removed for histological and immunohistological analysis. SHR-->SHR developed a significantly higher blood pressure than BBOK-->SHR. Blood pressure in BBOK-->BBOK was significantly lower than in the other two groups. The degree of glomerulosclerosis was similarly increased in allografted (BBOK-->SHR) and SHR-->SHR kidneys as compared with the BBOK-->BBOK kidneys (P < 0.05). Infiltration of ED-1+ monocyte/macrophages and OX19 pan-T-cells was most pronounced in allografts (BBOK-->SHR) and was also increased in SHR-->SHR as compared with BBOK-->BBOK. Our results indicate that hypertension accelerates the morphological and immunohistological changes characteristic of grafts undergoing chronic rejection. However, our findings support the hypothesis that alloantigen-dependent factors are of greater important.

Animals↗
PubMed1998

Hungarian population data for six STR loci.

Population genetic studies were carried out on a South Hungarian population (n = 111 individuals). The short tandem repeat (STR) systems Hum VWA, HumTH01, HumF13B, HumCD4, HumFES and HumFIBRA (FGA) were investigated by PCR amplification. All loci met Hardy-Weinberg expectations.

Alleles↗