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Biomedical subjects

M Molnar

Publications and source records attributed to M Molnar.

At least 37 records · Page 2Linked to original sources
PubMed1994

Vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA in the rat retina: adult distribution and developmental expression.

In the adult nervous system, vasoactive intestinal polypeptide acts as a neurotransmitter or neuromodulator, and during development, it may also act as a neurotrophic factor. In the adult mammalian retina, this peptide is contained in a population of wide-field amacrine cells. Using in situ hybridization histochemistry, we examined the distribution and developmental expression of vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA in the rat retina. Retinas collected from birth to adulthood were hybridized with an RNA probe as whole mounts, and then cut either perpendicular or parallel to the vitreal surface. Adult retinas were used in double labeling experiments for the visualization of both the hybridization signal and vasoactive intestinal polypeptide immunoreactivity in the same tissue section. In adult retinas, vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA is localized to amacrine cells positioned in the proximal inner nuclear layer, and rarely to displaced amacrine cells in the inner plexiform layer and ganglion cell layer. The neurons expressing this messenger RNA are sparsely distributed, with a non-random distribution and densities of about 190 cells/mm2. An estimate of their total number gives about 12,350 cells/retina. The double labeling experiments showed that the hybridization signal is specifically confined to neurons displaying vasoactive intestinal polypeptide immunoreactivity. Vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA is first detected at postnatal day 5 in cells located in the proximal part of the neuroblastic layer. A greater number of these neurons is present in the inner nuclear layer at postnatal day 10, and a few labeled neurons are also detected in the inner plexiform layer and in the ganglion cell layer. At this time, vasoactive intestinal polypeptide/peptide histidine isoleucine messenger RNA-containing amacrines in the inner nuclear layer are non-randomly distributed on the retinal surface, as in adult retinas. At postnatal day 15 (eye opening), there is a peak in both the density and the estimated number of labeled neurons, and their pattern of distribution in the retinal layers is similar to that in the adult. The present study shows that in the adult rat retina vasoactive intestinal polypeptide and peptide histidine isoleucine are synthesized in a sparsely distributed amacrine cell population, extending previous immunohistochemical findings. The appearance of vasoactive intestinal polypeptide peptide histidine isoleucine messenger RNA during the first postnatal week is consistent with the reported appearance of other transmitter-identified amacrine cell populations.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

[Results of laryngo-microscopic examinations over a 10-year period at the ORL Department of the Senta Hospital].

In the period from 1980-1989, 199 laryngomicroscopical examinations were conducted at our department. There were 20 cases of laryngeal carcinoma, 55 cases of keratosis with the presence of dysplasia in 21.8%, as well as 19 papillomas in adult individuals. In our material keratoses appear a few years before the onset of laryngeal carcinoma in an average statistical distribution. With one exception, the carcinomas were detected before the appearance of metastases. Our data indicate the exceptional benefit of laryngomicroscopy in the detection of precancerous lesions and carcinoma of the larynx.

Adolescent↗
PubMed1987

Luteinizing hormone-induced intracellular calcium mobilization in granulosa cells: comparison with forskolin and 8-bromo-adenosine 3',5'-monophosphate.

Digitonin-permeabilized avian granulosa cells were used as a model to study the effects of LH, 8-bromo-cAMP (8-Br-cAMP), and forskolin on intracellular calcium mobilization. LH caused a biphasic calcium efflux. There was a small but significant (P less than 0.05) calcium release within 1-2 min (rapid phase) with an ED50 of 35 ng/ml, followed by a larger one after 5 min (slow phase) with an ED50 of 10 ng/ml. The intracellular calcium antagonist TMB-8 inhibited the action of LH in both phases. Forskolin had no effect on calcium efflux during the rapid phase. However, it stimulated intracellular calcium efflux in a dose-dependent manner in the slow phase with an ED50 of 30 microM. Low doses of 8-Br-cAMP caused a small but significant increase in calcium uptake corresponding to the rapid phase, although high concentrations of 8-Br-cAMP caused efflux in the slow phase (ED50, 0.7 mM). Both LH and 8-Br-cAMP mobilized calcium from a nonmitochondrial pool, whereas forskolin induced calcium efflux from a nonendoplasmic reticular site. Apparently receptor-mediated (LH) and nonreceptor-mediated (forskolin and 8-Br-cAMP) intracellular calcium mobilization are qualitatively different, suggesting that rapid intracellular calcium mobilization may represent one of the initial steps in the mechanism of action of LH.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1987

Radioactive iodine exchange reaction of HIPDM: kinetics and mechanism.

In conjunction with single photon emission computed tomography (SPECT), iodine-123 (123I)-labeled N,N,N'-trimethyl-[2-hydroxy-3-methyl-5-iodobenzyl]-1,3-propanediamine (HIPDM) has been used clinically as a regional cerebral perfusion imaging agent. The [123I]HIPDM can be prepared by a simple aqueous exchange reaction in a kit form. We synthesized unlabeled HIPDM by condensation of 2-hydroxy-3-methyl-5-iodobezaldehyde and N,N,N'-trimethyl-1,3-propanediamine, followed by a sodium borohydride reduction reaction. The kinetics of the radioactive iodine exchange reaction for the preparation of [123I]HIDM is controlled by the pH, the temperature, and the presence of reductant (sodium bisulfite), and oxidant (sodium iodate). The reaction is a second order iodine-iodine exchange with an activation energy of 30.6 kcal/mole. The mechanism of this reaction probably involves the formation of an active 1+ or iodine free radical, which is sensitive to the presence of a reductant, such as sodium bisulfite.

Drug Interactions↗
PubMed1985

Synthesis of new bis(aminoethanethiol) (BAT) derivatives: possible ligands for 99mTc brain imaging agents.

In developing new brain perfusion imaging agents for single photon emission computed tomography (SPECT), five 99mTc-labeled neutral bis(aminoethanethiol) (BAT) derivatives capable of crossing the blood-brain barrier are reported. The five ligands are prepared by two versatile synthetic methods that can specifically introduce substituents on one of the carbons between two nitrogens. These ligands formed stable and neutral complexes with the reduced 99mTc, using either Sn(II) or sodium borohydride to reduce sodium [99mTc]pertechnetate. The biodistribution in rats was evaluated with [125I]iodoantipyrine, a freely diffusible tracer, as the internal reference. Compounds with a free hydroxyl group, 6 and 15, showed lower brain uptake. High initial brain uptake was observed for compounds 10 and 14, 1.28 and 2.30% dose/organ, respectively. Compounds of this type may be used as a basis for future structural modification to improve brain uptake and retention.

Animals↗
PubMed1984

Synthesis and biodistribution of neutral lipid-soluble Tc-99m complexes that cross the blood-brain barrier.

Three Tc-99m-labeled neutral 1,2-dithia-5,8-diazacyclodecane (BAT) chelates that are capable of crossing the blood-brain barrier (BBB) were prepared and evaluated. Biodistribution (i.v.) in rats showed a significant brain uptake (1-3%/whole brain) at 2 min. At 15 min the uptake dropped to about a tenth of the original level, indicating free passage in both directions across the BBB. Gamma camera images of a monkey confirmed the high initial brain uptake. This group of Tc-99m BAT compounds clearly exhibited in vivo stability and the ability to cross the BBB after an i.v. injection. Derivatives containing tertiary amine groups should have prolonged brain retention and might be suitable for SPECT studies of brain perfusion.

Animals↗
PubMed1977

Questionable usefulness of gamma-glutamyl transpeptidase test in legal medicine.

Because of the high level of GGT activity in semen, the suggestion was made that this enzyme could serve as a test in forensic medical practice; especially in rape cases. Comparisons of GGT and ACP tests revealed, however, that GGT is not sensitive enough and did not show acceptable specificity. One can conclude that GGT cannot be recommended either as a confirmatory test or as a substitute for ACP determinations in rape cases.

Acid Phosphatase↗
PubMedDate not supplied

Polyploidy in the haplontic yeast Schizosaccharomyces pombe: construction and analysis of strains.

The fission yeast Schizosaccharomyces pombe has a haplontic life cycle in which the diplophase is confined to the zygote. Through the use of one- and two-step protoplast fusions we show that the ploidy can be increased up to pentaploid. The polyploid fusion products are rather unstable and segregate cells of lower ploidies by gradual loss of chromosomes during mitotic divisions. The polyploid cells conjugate normally but are prone to arrest at various stages of meiosis (1-, 2- and 3-spored asci, binucleate spores) and/or produce inviable, most probably aneuploid, spores. Marker segregation in the complete tetrads indicates the multiple association of homologous chromosomes. In tetra- and penta-ploid meiosis, multispored (6- to 7-spored) asci are also produced, probably by postmeiotic division of the nuclei.

Cloning, Molecular↗
PubMedDate not supplied

Prognostic value of fluorescein angiography of the funds in diabetic children.

A positive fluorescein angiographic (FLAG) finding is a frequent occurrence in ophthalmoscopically negative cases. By repeated FLAG examinations good follow-up of the variability of the finding is possible. After 4--8 years of diabetes, ophthalmoscopically diagnosable retinopathy is to be expected in the patients in whom the initial FLAG examination showed signs of angiopathy.

Adolescent↗
PubMedDate not supplied

Application of chaos theory to biology and medicine.

The application of "chaos theory" to the physical and chemical sciences has resolved some long-standing problems, such as how to calculate a turbulent event in fluid dynamics or how to quantify the pathway of a molecule during Brownian motion. Biology and medicine also have unresolved problems, such as how to predict the occurrence of lethal arrhythmias or epileptic seizures. The quantification of a chaotic system, such as the nervous system, can occur by calculating the correlation dimension (D2) of a sample of the data that the system generates. For biological systems, the point correlation dimension (PD2) has an advantage in that it does not presume stationarity of the data, as the D2 algorithm must, and thus can track the transient non-stationarities that occur when the systems changes state. Such non-stationarities arise during normal functioning (e.g., during an event-related potential) or in pathology (e.g., in epilepsy or cardiac arrhythmogenesis). When stochastic analyses, such as the standard deviation or power spectrum, are performed on the same data they often have a reduced sensitivity and specificity compared to the dimensional measures. For example, a reduced standard deviation of heartbeat intervals can predict increased mortality in a group of cardiac subjects, each of which has a reduced standard deviation, but it cannot specify which individuals will or will not manifest lethal arrhythmogenesis; in contrast, the PD2 of the very same data can specify which patients will manifest sudden death. The explanation for the greater sensitivity and specificity of the dimensional measures is that they are deterministic, and thus are more accurate in quantifying the time-series. This accuracy appears to be significant in detecting pathology in biological systems, and thus the use of deterministic measures may lead to breakthroughs in the diagnosis and treatment of some medical disorders.

Animals↗
PubMedDate not supplied

The point correlation dimension: performance with nonstationary surrogate data and noise.

The dynamics of many biological systems have recently been attributed to low-dimensional chaos instead of high-dimensional noise, as previously though. Because biological data are invariably nonstationary, especially when recorded over a long interval, the conventional measures of low-dimensional chaos (e.g., the correlation dimension algorithms) cannot be applied. A new algorithm, the point correction dimension (PD2i) was developed to deal with this fundamental problem. In this article we describe the details of the algorithm and show that the local mean PD2i will accurately track dimension in nonstationary surrogate data.

Algorithms↗
PubMedDate not supplied

Preproenkephalin messenger RNA-containing amacrine cells in the chicken retina identified with in situ hybridization histochemistry.

Enkephalin peptides are present in the retina of several vertebrate species. In the avian retina, enkephalin immunoreactivity is primarily localized to a population of amacrine cells. In the present study, we determined the localization of cells expressing preproenkephalin (PPE) mRNA, which encodes the precursor of enkephalin peptides, in adult as well as in embryonic chicken retinas. The localization of PPE mRNA-expressing cells to the proximal inner nuclear layer (INL) in the adult chicken retina is similar to that of enkephalin-immunoreactive cells observed in previous studies, indicating that amacrine cells expressing PPE mRNA synthesize Met5- and Leu5-enkephalin peptides and related extended forms. Specific hybridization signal is absent in retinas at embryonic day (E) 11, but it is detected in retinas at E 15 and at hatching. PPE mRNA-expressing cells at these ages are located in the proximal INL, and they can be classified as amacrine cells on the basis of their soma size and laminar position. These findings confirm and extend previous observations on the presence of opioid peptides in amacrine cells of the chicken retina. The presence of PPE mRNA at embryonic ages, together with the evidence that enkephalins influence developmental processes, suggests that these peptides modulate retinal maturation in birds.

Animals↗
PubMedDate not supplied

Personality, stress, and injuries in professional ballet dancers.

Twenty-nine soloist and principal dancers (mean age, 29.08 years) from America's two most celebrated ballet companies were administered questionnaires measuring personality (API), occupational stress (OES), strain (PSQ), and coping mechanisms (PRQ), and injury patterns. The results revealed that male dancers demonstrated significantly more negative personality traits and psychological distress than female dancers or men in the general population. In addition, physical stress and personality traits, characteristic of the "overachiever," distinguished injured dancers. It is suggested that classical ballet's emphasis on the ballerina may be at odds with a masculine identity in male dancers. Furthermore, the qualities that lead to success in this profession may contribute to injuries if carried to an extreme.

Adult↗
PubMedDate not supplied

A profile of the musculoskeletal characteristics of elite professional ballet dancers.

Twenty-eight principal dancers and soloists from America's two most famous ballet companies were examined for anthropometric measurements, including flexibility, muscle strength, and joint range of motion. Both male and female dancers were flexible, but not hypermobile, and did not differ significantly from each other. Marked differences were found between the range of motion of the hip and ankle in the dancers and the norms for the general population. The increased external rotation of the hip in women was accompanied by a loss in internal rotation, resulting in an increased range of motion with an externally rotated orientation. The men, however, lost more internal rotation than they gained in external rotation. These data raise the possibility of a torsional component to the turned-out hip position in elite female professional ballet dancers. In addition, significant anatomic differences separate elite dancers of both sexes from the normal population.

Adult↗
PubMedDate not supplied

[Non-culturable Koch bacilli during antitubercular chemotherapy].

The authors have performed 58435 microscopic examinations, of which 3813 were positive, and found 209 (5,48%) cases of non-cultivable Koch bacilli. The major bacteriological, clinico-evolutive and therapeutical aspects are examined. Most of the cases showing a syndrome of positive homogenate with a negative culture were rather recent ones (an evolution of less than 2 years in 73,68% of the total) and the highest frequency was found in those in which the treatment was in its first year. No direct relationship could be demonstrated between the number of germs (the Gaffky scale) and the frequency of the syndrome. The factors influencing the occurrence and the development of the syndrome are: the structure of the lesions, the method of bacteriologic examination, the therapy applied, and a certain immunologic reactivity. According to the authors the significance of this syndrome is positive in most of the cases, indicating a regression that has not been completed. The most reasonable attitude is a differentiated one, depending on each case, integrating the data obtained by the bacteriological examination in the therapeutic and evolutive clinico-radiologic context.

Antitubercular Agents↗