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Biomedical subjects

T Horvath

Publications and source records attributed to T Horvath.

At least 19 recordsLinked to original sources
PubMed2003

[Immunologic control of HIV-1 infection. Fantasy or soon reality?].

The human immunodeficiency virus-1 (HIV-1) preferentially infects CD4+ cells, leading to their destruction. In contrast to other viral infections, the immune system is unable to keep the HIV infection under permanent control in most cases. This failure ultimatively results in immunodeficiency with occurrence of AIDS-defining diseases. In recent years, highly active antiretroviral therapy (HAART) has become available, and the number of AIDS cases and deaths have decreased dramatically. However, limitations of HAART become more apparent, demanding greater emphasis on search for alternative approaches. Stimulation and modulation of the immune response to HIV are new and promising strategies. A prerequisite, however, is the knowledge about immunologic defense mechanisms against HIV. In this article, the major factors of innate and acquired immune responses to HIV are described.

AIDS Vaccines↗
PubMed2001

Turnover of rat brain perivascular cells.

Brain perivascular spaces harbor a population of cells which exhibit high phagocytic capacity. Therefore, these cells can be labeled by intraventricular injection of tracers. Such perivascular cells at the interface between blood and brain are believed to belong to the monocyte/macrophage lineage and to be involved in antigen presentation. Currently, it is unclear whether these cells undergo a continuous turnover by entering and leaving the bloodstream. Using bone-marrow-chimeric animals, migration of donor macrophages into brain perivascular spaces has been reported. On the other hand, following intracerebral injection of india ink into nontransplanted animals, ink-labeled perivascular cells were still found 2 years after injection, suggesting a high stability of this cell pool. Thus, the turnover of perivascular cells observed in chimeras might be a result of bone marrow transplantation rather than a physiological occurrence. To address this issue, we monitored de novo invasion of macrophages into perivascular spaces of apparently healthy adult rats by applying techniques other than bone marrow transplantation, (i) consecutive injections of different tracers and (ii) ex vivo isolation of macrophages from the blood, cell labeling, and reinjection into the same animal to avoid MHC mismatch. Both approaches revealed vivid de novo invasion of macrophages into perivascular spaces, but not into brain parenchyma, rendering untenable the concept of perivascular cells forming a stable population of macrophages in the brain. Thus, brain perivascular spaces are under permanent immune surveillance of blood borne macrophages in normal adult rats.

Animals↗
PubMed1999

Estrogen and microglia: A regulatory system that affects the brain.

Sex hormones are involved in the physiological regulation of several aspects of behavior and neuroendocrine events. It has been accepted that such effects are mediated directly by steroid actions on neurons; however, new studies have shown that the glial cells are also affected by gonadal steroids. The microglia are one specialized brain glial cell type, which is a target for estrogen actions. In fact, we believe that many of the immune and nonimmune regulatory functions of microglia in the brain are influenced directly by estrogen via expression and secretion of cytokines, and growth factors by the microglia. The present review details only a section of the known aspects of microglial function, focusing mainly on nonimmune regulatory actions in the brain and their functional relationship with sex hormones. Moreover, we present evidence for the presence of estrogen receptor-beta (ERbeta) in rat microglial cells.

Animals↗
PubMed1997

The interactive language of the hypothalamus for the gonadotropin releasing hormone (GNRH) system.

The enormous diversity in neurochemical signals employed within the network of afferents to GnRH neurons is well-documented. An examination of novel and accumulating knowledge on the operation of these messengers indicates the presence of an interactive language governing GnRH secretion. The basic operational structures identified to date to affirm this interactive form of communication summarized in this review are the following: (i) the demonstration of interconnections within various components of the afferent network; (ii) coexistence and possible co-release of excitatory and inhibitory neurotransmitters/neuromodulators; (iii) co-action of various messengers at synaptic targets, and (4) modulation by gonadal steroids of the synthesis and release of signals and their receptors, and induction of synaptic plasticity for the timely relay of signals for GnRH secretion. Unraveling the molecular sequelae that promote this interactive communication to elicit periodic GnRH secretion is now a new challenge.

Afferent Pathways↗
PubMed1997

Social support and psychopathology in the war zone.

Unit cohesion and homecoming support are examined for their protective effects on the development of posttraumatic stress disorder (PTSD) and other psychopathology. Data on 1198 male theater veterans were taken from the National Vietnam Veterans Readjustment Study. Unit cohesion had no significant relationship, as a direct effect, to either PTSD or other psychopathology. In a pattern that was opposite to predictions from the buffering hypothesis of support, however, a high level of unit cohesion in combination with high war zone stress was associated with the highest levels of PTSD and psychopathology. This is consistent with Israeli experiences, suggesting that unit cohesion may have detrimental long-term effects on psychological well-being. In contrast, homecoming support was related negatively as a direct effect to both PTSD and other psychopathology. In addition, interaction results, consistent with the buffering hypothesis, suggest that the protective effects of homecoming support are magnified for veterans with high compared with low levels of exposure.

Adult↗
PubMed1997

Assessing axis II disorders by informant interview.

Although much of personality disorder research depends on diagnostic data obtained directly from patients, this approach has rarely been compared to interviews with knowledgeable informants. The purpose of this study was to determine the diagnostic agreement between these two assessment methods, as well as their relative contribution to the formulation of consensus diagnoses. Sixty-two psychiatric patients were assessed directly with the Structured Interview for DSM-III Personality Disorders (SIDP), and were asked to nominate an informant--either a family member or friend--to provide information about the patient in an interview with the same instrument. Informant interviews were conducted blind to patient-based information whenever feasible, and diagnostic consensus was achieved by an independent review of all available data by a senior clinician. Diagnostic agreement between patient-based and informant-based personality disorder interview was poor, confirming the findings of two previous studies. Information obtained from patients tended to be given greater weight in formulating consensus diagnoses than information provided by informants. However, about one quarter of diagnostic disagreements were resolved in favor of informant-based information. In contrast to a previous study, the inclusion of informant information did not appear to reveal greater psychopathology in patients. We conclude that supplementing direct patient interview with data provided by a knowledgeable informant appears to enhance the resolution of some personality disorder diagnoses. The utility of informant interviews may depend on an analysis of the costs and benefits of this additional degree of descriptive refinement.

Adult↗
PubMed1996

Event-related potentials in schizotypal personality disorder.

This study examined whether abnormalities in event-related potentials (ERPs), reported in schizophrenia, extend to patients with schizotypal personality disorder (SPD). Auditory ERPs in an oddball paradigm were obtained in 19 SPD patients, 17 schizophrenic patients, and 20 normal control subjects (NCs). Schizophrenic patients had lower P300 amplitude than NCs; the P300 amplitude of SPD patients was intermediate, showing a linear trend but not a significant group difference. P200 amplitudes showed a similar trend. SPD patients had N100 and N200 amplitudes intermediate to schizophrenic patients and NCs, without significant group differences. Results suggest diminished P300 amplitude may not be as prominent in SPD as in schizophrenia. Studies with larger sample sizes, multiple lead assessment strategies, and more demanding tasks may further characterize ERP deficits in schizophrenia-spectrum disorders such as SPD.

Adult↗
PubMed1995

Diurnal neuroendocrine and autonomic function in acute and remitted depressed male patients.

This study evaluated diurnal data gathered hourly (1000 to 1800 hours) in males during acute depression and during remission of depression and in age-range/gender-matched normal controls. Mean, peak, variability, and time-course of the noradrenergic metabolite, plasma 3-methoxy, 4-hydroxyphenylglycol [MHPG]), plasma cortisol, and autonomic (mean arterial blood pressure [MAP] and heart rate) variables were examined. Compared to controls, acutely depressed, but not remitted depressed, patients had 1) an earlier plasma MHPG peak, 2) a greater intragroup variability of plasma MHPG, 3) a higher plasma cortisol concentration, 4) a lower MAP, and 5) tended to increase MAP more slowly than did the normal controls. The time course of diurnal heart rate also differed in acutely depressed patients from controls: acutely depressed patients started higher and converged by midday to normal levels. These diurnal data lend limited support to the dysregulation hypotheses of depression that suggest normal circadian rhythmicities are altered or disrupted in acute depression and that peripheral manifestations of central dysregulation normalize in remission of depression.

Adult↗
PubMed1993

The cortisol response to clonidine in acute and remitted depressed men.

To assess the relationship between the hypothalamo-pituitary-adrenal (HPA) axis and the noradrenergic system in patients with major depression, 26 normal controls, 32 acutely depressed patients, and 21 patients with remitted depression, all men, were administered intravenous clonidine (2 micrograms/kg) or placebo. Acute, but not remitted, depressed patients had a greater plasma cortisol baseline than did normal controls (t = 2.0, p < 0.03). Only acutely depressed patients had a greater decrease in plasma cortisol in response to clonidine than to placebo (t = 2.5, p < 0.02). Statistically controlling for both diurnal variation and baseline cortisol, acute, but not remitted, depressed patients had a greater decrease in plasma cortisol in response to clonidine than did the controls (analysis of covariance: F[1,35] = 4.26, p < 0.05). These results support a state-dependent noradrenergic-HPA axis regulatory disturbance in depressed patients, suggesting that clonidine inhibits the elevated plasma cortisol in acute depression but not the normal concentrations observed in remitted depression or healthy controls.

Adult↗
PubMed1993

Role of neuropeptide-Y in episodic luteinizing hormone release in ovariectomized rats: an excitatory component and opioid involvement.

We tested the hypothesis that hypothalamic neuropeptide-Y (NPY) is an excitatory signal in the episodic secretion of LH in ovariectomized (ovx) rats and that the suppression of LH secretion that consistently follows intracerebroventricular administration of NPY is due to concurrent release of opioids or CRH, both previously shown to readily inhibit LH release. In the first experiment, ovx rats received continuous intraventricular infusion of either serum containing NPY antibodies (NPY-Ab) or normal rabbit serum (control) at dilutions of 1:5 or 1:1. NPY-Ab infusion at a 1:5 dilution significantly decreased mean plasma LH levels and LH pulse amplitude without affecting LH pulse frequency over a 3-h period of observation. However, infusion of relatively more concentrated NPY-Ab (1:1) markedly decreased not only mean plasma LH levels and LH pulse amplitude, but also the frequency of LH episodes. In the next experiment, we observed that intraventricular administration of NPY (0.2 nmol) suppressed LH release for 60 min. However, blockade of opiate receptors with iv infusion of naloxone (2 mg/h) before and after NPY injection completely counteracted the NPY-induced inhibition of LH release. On the other hand, prior blockade of the CRH receptors with alpha-helical CRH-(9-41) (25 or 100 micrograms/rat) was ineffective in reversing the inhibitory LH response of NPY (0.125 nmol). These results together with our previous demonstration of morphological communication between NPY and beta-endorphin neurons, show that suppression of LH by exogenous NPY in ovx rats may result from concurrent stimulation of opioids, primarily beta-endorphin. However, diminution of all parameters of episodic LH secretion by NPY-Ab affirms the notion that the NPY network is a physiologically important excitatory component of the hypothalamic pulse generator circuitry that regulates episodic LH secretion in rats.

Animals↗
PubMed1992

Auditory event-related potentials in HIV-1 infection: a study in the drug-user risk group.

Features of event-related potentials (ERPs) may be sensitive and clinically useful markers of central nervous system infection by the human immunodeficiency virus (HIV-1); however, this application has not been studied in the risk group of intravenous drug users. Auditory ERPs generated by an "oddball" paradigm were analyzed for 39 male drug abusers as part of a multimodal assessment. Stage of HIV-1 infection was associated with prolongations of P1, N1, and P3 components of the ERP waveform. Only patients with full acquired immunodeficiency syndrome showed statistically significant increases in waveform prolongations. Specific neuropsychological deficits were not related to waveform latency prolongations.

AIDS Dementia Complex↗
PubMed1990

Eye tracking impairment in clinically identified patients with schizotypal personality disorder.

Eye tracking accuracy, which has been found to be impaired in schizophrenic patients and their relatives, was assessed in 26 patients with schizotypal personality disorder, 17 control subjects with other non-schizophrenia-related personality disorders, 29 normal control subjects, and 44 schizophrenic patients. Both schizotypal and schizophrenic patients, but not control subjects with other personality disorders, demonstrated significantly more impaired tracking than the normal control subjects. These results suggest that patients with clinically defined schizotypal personality disorder may be biologically related to schizophrenic patients as part of a spectrum of schizophrenia-related disorders.

Adult↗
PubMed1990

[Determination of hemoglobin concentration using the hemoglobin azide method in traumatic emergencies].

UNLABELLED: The present study examined the clinical practicability of a new hemoglobin measurement device based on a modified azide-methemoglobin reaction (HiN3 method) in trauma patients. The accuracy of the HiN3 method was compared to the internationally well accepted hemiglobincyanide method (HiCN method) in arterial, capillary, and venous blood samples. PATIENTS AND METHODS: 1. Comparison of the methods. In 62 trauma patients, hemoglobin measurements using the HiN3 method were compared to results obtained by the HiCN method. Blood samples were taken simultaneously from the same patient to evaluate each measurement procedure in arterial (group 1), capillary (group 2), and venous blood samples (group 3). 2. Accuracy. To evaluate the accuracy of both methods we compared two venous blood samples taken simultaneously from the same patient. 3. Reproducibility. For measurement of the reproducibility of the HiN3 method, the first two results of each three-time-measurement were compared. Statistical analysis of the results was performed using regression analysis. RESULTS: 1. Comparison of the methods. Comparing the results of hemoglobin measurements resulting from the HiN3 and HiCN methods, a strong correlation was found in arterial (Fig. 2), capillary (Fig. 3), and venous blood (Fig. 4). 2. Accuracy. The HiN3 method had an accuracy of +/- 1.47% and the HiCN method +/- 2.55%. 3. The reproducibility of the HiN3 method was +/- 1.25% (Fig. 5); however, one pair of samples did show a significantly different initial value (Hb 8.4 g/dl in I, but 10.4 g/dl in I and III). DISCUSSION: From our examinations in trauma patients, we can recommend this easy to handle device, particularly for acute diagnostic purposes in emergency patients and for trend evaluations both in the hospital and in the prehospital period for rapid and precise hemoglobin determinations.

Adult↗
PubMed1989

Evaluation of a young child's behavior: effects of attractiveness and sex.

Facial drawings of 2- or 4-yr.-old boys or girls differing in attractiveness were attached to an episode which depicted a mild misbehavior. Neither the attribution of responsibility for the behavior nor the choice of an indulgent vs punitive response was associated with the child's attractiveness, sex, or age. These findings suggest that the halo effects of attractiveness discriminations may not be fully operative at these ages.

Adult↗
PubMed1986

Speleotherapy: a special kind of climatotherapy, its role in respiratory rehabilitation.

Speleotherapy, the use of the climate of caves, is an accepted but not widely known therapeutic measure in the treatment of chronic obstructive airway diseases. This study summarizes the therapeutic experiences of more than 4000 patients who were treated in a 10-year period in a hospital-cave complex in Tapolca, Hungary. A sharp and long-lasting clinical improvement and a significant recovery from airway obstruction could be observed in the overwhelming majority of patients. It is established that the microclimate of some caves can beneficially affect these disorders, but the cave should be considered as an optimal environment for complex respiratory rehabilitation.

Asthma↗
PubMed1983

Acetylcholinesterase activity in CSF in schizophrenia, depression, Alzheimer's disease and normals.

Acetylcholinesterase (AChE) activity and protein were measured in the CSF of patients with Alzheimer's disease, depression, schizophrenia with and without tardive dyskinesia, and control subjects. AChE activity was assayed by a radioenzymatic method involving the direct extraction of hydrolyzed 3H-acetate into a toluene-based scintillation fluid followed by liquid scintillation spectrometry. AChE activity was proportional to the amount of CSF protein. Greater than 90% of AChE activity in CSF could be inhibited by 10(-3) M eserine. In addition, activity remained stable despite repeated freeze-thawing in an acetone-dry ice bath. Age was found to be positively correlated with CSF protein and AChE activity expressed per volume CSF, but not with AChE measured per milligram protein. No differences between diagnostic groups were found on either measure of AChE when the extraneous factors of age and CSF protein concentrations were controlled, nor were any differences found between groups for CSF protein when age was controlled.

Acetylcholinesterase↗