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Biomedical subjects

E Nemeth

Publications and source records attributed to E Nemeth.

At least 19 recordsLinked to original sources
PubMed2005

Iron-regulatory protein hepcidin is increased in female athletes after a marathon.

The propose of this study was to determine the influence of marathon race on hepcidin excretion in female athletes (age 26-45 years). Urine samples were taken before, immediately after, 1 and 3 days after the race. In the average, hepcidin transiently increased at day 1 from 32 to 85 ng/mg creatinine. We propose that the frequently observed iron deficiency of females runners is caused by elevated hepcidin levels.

Adult↗
PubMed2002

[Development of a jet tracheoscope. Value and possible uses in superimposed high frequency jet ventilation in endoscopic surgery of the respiratory tract].

BACKGROUND AND OBJECTIVE: Tubeless jet-ventilation offers the surgeon an unimpaired surgical field and is therefore widely used in endolaryngeal surgery. In order to permit endotracheal surgery using the same devices and instruments as those used for the larynx, we have developed special jet-tracheoscopes. Here, we report on our experience with superimposed high-frequency jet-ventilation (SHFJV) together with total intravenous anaesthesia (TIVA) in endolaryngeal and especially endotracheal surgery. PATIENTS AND METHODS: The medical reports of 172 patients (91 females, 81 males) who had undergone endolaryngeal or endotracheal surgery in SHFJV were analysed retrospectively. RESULTS: Sufficient ventilation was possible in all cases and no vitally critical situation occurred. The main indication was laryngotracheal stenosis of different origins. No significant advantages could be observed in phonosurgery. There was no difficulty in exposing the endolarynx and subglottis with the currently available laryngoscopes (five sizes). The newly developed jet-tracheoscopes (two sizes) allowed a quick and safe extension of the operating field onto the tracheal bifurcation. CONCLUSIONS: SHFJV together with TIVA enlarges the diagnostic and therapeutic options in endoscopic surgery of the respiratory tract and is in many cases the precondition for endoscopic treatment without tracheotomy. In particular, the newly developed jet-tracheoscopes widen the spectrum of endoscopic surgery and allow the use of the micromanipulator guided CO2-laser in the trachea.

Adolescent↗
PubMed2001

Differential degradation of antbird songs in a neotropical rainforest: adaptation to perch height?

Habitat characteristics that affect transmission and degradation of acoustical signals should influence strongly the evolution of bird songs. In this study propagation properties of songs of five antbird species were measured in a rainforest in southern Venezuela. The investigated species (Myrmothera campanisona, Thamnophilus aethiops, Thamnophilus amazonicus, Myrmotherula axillaris, and Herpsilochmus dorsimaculatus) use different song post heights at all levels of the rainforest. Because there is a height-specific pattern in degradation, it is hypothesized that their songs are adapted to species-specific transmission paths. To test this assumption, transmission parameters (excess attenuation, signal-to-noise ratio, and blur ratio) were measured for the songs at five different heights and at three different distances. In three of the five species, the results indicate a strong influence of environmental conditions on the design of the vocalizations. Degradation was minimized by the concentration of the signal to a narrower frequency range, the usage of lower frequencies, or a slower time structure for the songs near the ground. The results are discussed in relation to acoustical models of sound propagation and physiology, and it is suggested that height-dependent degradation within a forest is an important selection pressure for transmissibility in avian communication.

Adaptation, Physiological↗
PubMed2000

BRCA1 promoter region hypermethylation in ovarian carcinoma: a population-based study.

There is a clear association between germ-line BRCA1 mutations and inherited ovarian cancer; however, the association between BRCA1 mutations and sporadic ovarian cancer remains ambiguous. The frequency of BRCA1 promoter hypermethylation as an epigenetic means of BRCA1 inactivation was determined for a large, population-based cohort of ovarian cancer patients. BRCA1 promoter hypermethylation was determined by methylation-specific restriction digestion of tumor DNA, followed by Southern blot analysis and confirmed by methylation-specific PCR. BRCA1 promoter hypermethylation was observed in 12 of 98 ovarian tumors. BRCA1 methylation status of the primary tumor was conserved in six recurrent tumors after interim chemotherapy. None of the 12 tumors with BRCA1 promoter hypermethylation demonstrated BRCA1 protein expression by immunohistochemistry. BRCA1 methylation was only seen in ovarian cancer patients without a family history suggestive of a breast/ ovarian cancer syndrome. Therefore, the 12 BRCA1 methylated tumors represented 15% (12 of 81) of the sporadic cancers analyzed in this study. Although the clinical significance of BRCA1 promoter hypermethylation is yet to be determined, promoter hypermethylation may be an alternative to mutation in causing the inactivation of the BRCA1 tumor suppressor gene in sporadic ovarian cancer.

Alleles↗
PubMed2000

Three levels of lateral inhibition: A space-time study of the retina of the tiger salamander.

The space-time patterns of activity generated across arrays of retinal neurons can provide a sensitive measurement of the effects of neural interactions underlying retinal activity. We measured the excitatory and inhibitory components associated with these patterns at each cellular level in the retina and further dissected inhibitory components pharmacologically. Using perforated and loose patch recording, we measured the voltages, currents, or spiking at 91 lateral positions covering approximately 2 mm in response to a flashed 300-microm-wide bar. First, we showed how the effect of well known lateral inhibition at the outer retina, mediated by horizontal cells, evolved in time to compress the spatial representation of the stimulus bar at ON and OFF bipolar cell bodies as well as horizontal cells. Second, we showed, for the first time, how GABA(C) receptor mediated amacrine cell feedback to bipolar terminals compresses the spatial representation of the stimulus bar at ON bipolar terminals over time. Third, we showed that a third spatiotemporal compression exists at the ganglion cell layer that is mediated by feedforward amacrine cells via GABA(A) receptors. These three inhibitory mechanisms, via three different receptor types, appear to compensate for the effects of lateral diffusion of activity attributable to dendritic spread and electrical coupling between retinal neurons. As a consequence, the width of the final representation at the ganglion cell level approximates the dimensions of the original stimulus bar.

Action Potentials↗
PubMed2000

Fetal membrane distention: I. Differentially expressed genes regulated by acute distention in amniotic epithelial (WISH) cells.

OBJECTIVE: This study was undertaken to determine which genes were up-regulated by acute distention in an amniotic epithelial cell line and in human fetal membranes. STUDY DESIGN: WISH cells, a human amniotic epithelial cell line, were grown on silicone elastomer sheets coated with extracellular matrix and reproducibly distended by 40% in a novel device for 4 hours. Differential gene expression was analyzed by means of suppression subtractive hybridization. Expression of the identified genes was then quantitated by Northern blot analysis in fetal membrane explants after distention in the same device for 4 hours. The effect of distention on apoptosis of the cells and tissue samples was concomitantly studied by means of the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling method. RESULTS: The genes for interleukin 8 and pre-B-cell colony-enhancing factor were found to be up-regulated in both the WISH cells and the distended fetal membranes. The apoptotic index values in both the cells and the tissue samples were unaffected by distention. CONCLUSIONS: Acute distention induces the up-regulation of interleukin 8 and pre-B-cell colony-enhancing factor in both WISH cells and human fetal membranes and does not cause apoptosis.

Amnion↗
PubMed2000

Fetal membrane distention: II. Differentially expressed genes regulated by acute distention in vitro.

OBJECTIVE: This study was undertaken to identify genes with expression up-regulated by acute distention in the human fetal membranes. STUDY DESIGN: Fetal membrane explants were distended reproducibly in a novel device in vitro for 4 hours, and suppression subtractive hybridization was used to identify the candidate genes for up-regulation of expression in response to this stimulus. The up-regulation in response to distention was confirmed by quantitative Northern blot analysis both after a 4-hour in vitro distention and after labor in vivo. RESULTS: Suppression subtractive hybridization identified 3 genes with expression up-regulated by acute distention: an interferon-stimulated gene encoding a 54-kd protein, the gene for huntingtin-interacting protein 2 (a ubiquitin-conjugating enzyme), and a novel transcript. Expression of each of the distention-responsive genes found to be up-regulated in vitro was also up-regulated in fetal membranes in association with labor. CONCLUSIONS: Suppression subtractive hybridization was successfully applied to a complex tissue, the human fetal membranes, and 3 novel distention-responsive genes were identified. Both acute in vitro distention and labor in vivo up-regulate expression of at least 3 genes in the human fetal membranes.

Apoptosis Regulatory Proteins↗
PubMed1999

Plasma adrenaline concentrations during functional endoscopic sinus surgery.

OBJECTIVES/HYPOTHESIS: Vasoconstrictors (i.e., epinephrine) are routinely applied before functional endoscopic sinus surgery (FESS) but may have significant cardiac side effects. The controversy concerning clinical application of adrenaline is discussed. STUDY DESIGN: In a prospectively controlled study of 51 patients undergoing FESS we evaluated the absorption of adrenaline from standard cotton pledgets and submucous infiltration and the incidence of related side effects during surgery. Additionally, a control group of 12 patients undergoing tonsillectomy was investigated. METHODS: Plasma adrenaline concentrations were measured 1) before anesthesia, 2) after intubation, 3) after nasal packing with adrenaline soaked pledgets (adrenaline 1:1000) and submucous infiltration with 2 mL lidocaine with adrenaline 1:100,000 in each side, and 4) at end of surgery. The catecholamines were determined with a Merck-Hitachi Catecholamine Analyzer, model II (Merck, Darmstadt, Germany). Pulse, electrocardiogram (ECG), and blood pressure were monitored. RESULTS: In the FESS group, we found a remarkable decrease in systolic (S) as well as diastolic blood pressure (D) (P < .001), whereas the heart frequency was unaffected during surgery. All patients in the adrenaline group showed significant increase in plasma adrenaline (AD) concentrations in the third and fourth sample (P < .001). The control group, however, showed a significant rise in blood pressure only at beginning of surgery (P < .001) with cardiac pulse and plasma adrenaline concentrations unaffected by surgery or anesthesia. The often described severe side effects of adrenaline in combination with general anesthesia were not seen in any of our patients. CONCLUSIONS: Although systemic absorption of locally injected vasoconstrictors occurs, adrenaline-related side effects during FESS are extremely rare when the patient is monitored exactly.

Anesthesia, General↗
PubMed1998

Response to change is facilitated by a three-neuron disinhibitory pathway in the tiger salamander retina.

Most retinal ganglion cells respond only transiently, for approximately 150 msec at the onset and termination of a light flash. The responses are transient because it has been shown that bipolar-to-ganglion cell transmission is truncated after 150 msec by a feedback inhibition to bipolar cell terminals. The feedback inhibition itself must be delayed by approximately 150 msec to allow the initial bipolar-ganglion cell transmission. This study identifies a three-component serial synaptic pathway from glycinergic amacrine cells to GABAergic amacrine cells to bipolar cell terminals as one source of this delay. We used perforated and whole-cell patch-clamp recordings to measure the timing of light responses in amacrine, bipolar, and ganglion cells under control and glycine and GABA receptor-blocked conditions. Our results suggest that, after a light flash, a population of glycinergic amacrine cells responds first, inhibiting a population of GABAergic amacrine cells for approximately 150 msec. The GABAergic amacrine cells feed back to bipolar terminals, but only after the 150 msec delay, allowing the bipolar terminals to excite ganglion cells for the first 150 msec. Blocking the glycinergic amacrine cell activity with strychnine allows the GABAergic system to become active earlier. GABAergic amacrine cells then inhibit release from bipolar cells earlier. Under these conditions, the ganglion cell response to change would be decreased.

Animals↗
PubMed1998

Coupling of calcium receptors to inositol phosphate and cyclic AMP generation in mammalian cells and Xenopus laevis oocytes and immunodetection of receptor protein by region-specific antipeptide antisera.

Ca2+ and other divalent cations modulate parathyroid hormone secretion by interacting with cell-surface Ca2+-sensing receptors (CaRs). We assessed the ability of these receptors to couple to Ca2+ mobilization, inositol phosphate (InsP) accumulation, and cyclic AMP production in different expression systems. In Xenopus laevis oocytes injected with bovine parathyroid CaR cRNA, the addition of extracellular cations to 1.5 mM Ca2+, 5.5 mM Mg2+, or 10 microM Gd3+ significantly increased 45Ca efflux (p < 0.01). InsP accumulation also increased dramatically when adding these cations to human embryonic kidney (HEK) 293 cells stably transfected with wild-type bovine parathyroid CaR cDNA. Raising the extracellular [Ca2+] ([Ca2+]o) from 0.1 to > 1.4 mM in oocytes and to > 1.0 mM in HEK 293 cells stimulated significant increments in 45Ca efflux and InsP accumulation, respectively (p < 0.05). In contrast, Ca2+ and Mg2+ increased InsPs to a lesser extent in COS 7 cells transiently transfected with CaR cDNA. In HEK 293 cells stably expressing CaR cDNA, there were significant reductions in cAMP content when adding high Ca2+, Mg2+, Gd3+, or the CaR modulator NPS R-467. Three region-specific anti-CaR peptide antisera immunoblotted bands of approximately 140 and 155 kDa in membranes from CaR-transfected HEK 293 cells and bovine parathyroid tissue. Immunocytochemistry demonstrated strong cell-surface staining in CaR-transfected HEK 293 cells and parathyroid tissue, which was absent when antisera were preabsorbed with CaR peptides. These results indicate that the activation of the recombinant CaR by extracellular Ca2+ can couple negatively to adenylate cyclase but positively to phospholipase C (PLC), the latter at physiological [Ca2+]o.

Amino Acid Sequence↗
PubMed1998

Suppression subtractive hybridization (SSH) identifies prolactin stimulation of p38 MAP kinase gene expression in Nb2 T lymphoma cells: molecular cloning of rat p38 MAP kinase.

Suppression Subtractive Hybridization (SSH) has been used to compare rat Nb2 cells treated with prolactin for 1 hour with untreated cells. This new method for identifying differentially expressed genes showed that the mRNAs for at least three genes were elevated by such treatment, including a p38 mitogen activated protein (MAP) kinase. The p38 MAP kinase was cloned and the full length cDNA sequence was determined.

Animals↗
PubMed1994

Proliferative responses of endothelial cell populations to experimentally induced inflammatory lesions of gingival connective tissues in the cynomolgus monkey (Macaca fascicularis).

BACKGROUND: Endothelial cells exhibit heterogeneous and tissue-selective responses to injury and inflammation. The regulation of the size of endothelial populations in specific tissue sites is poorly characterized, particularly in soft connective tissues adjacent to bone. To investigate the effect of a primarily lymphocytic infiltrate on endothelial cell proliferation and growth of blood vessels, a primate model was used that reliably exhibits localized, distinct inflammatory, and destructive lesions in isolated sites of mucosal connective tissues adjacent to bone and epithelium around teeth. METHODS: Three Cynomolgus monkeys with healthy periodontium and two with spontaneously occurring inflammation or induced connective tissue destruction were pulse labeled with 3H-thymidine. Morphometric analyses of radioautographs from mid-sagittal supra-alveolar gingival connective tissues of incisor teeth were performed in sites subjacent to junctional, sulcular, and oral epithelium, in the body of the lamina propria and just superior to the alveolar bone crest. RESULTS: Subjacent to the sulcular epithelium there was a statistically significant (P < 0.01) increase in lymphocyte density between health and inflammation. The percentage of endothelial cells incorporating 3H-thymidine label (LI) and the number of blood vessels per unit area were significantly increased in this same site in inflamed samples (P < 0.02) but were not elevated further in lesions in which there was destruction of soft connective tissues. However, there was no increase of the numbers or the cross-sectional areas of blood vessels between samples of inflamed and destroyed tissues. CONCLUSIONS: 1) Experimentally induced inflammation and connective tissue destruction in the gingival connective tissues of Cynomolgus monkeys is associated with site-specific perturbations in the turnover of endothelial cells that is closely linked to lymphocytic infiltration; 2) the vascular response is a generalized increase in endothelial cell proliferation and blood vessel numbers but not lumen size or number of endothelial cells, suggesting the existence of homeostatic controls for preservation of the whole population in a steady state.

Animals↗
PubMed1994

The pericentriolar lattice of PtK2 cells exhibits temperature and calcium-modulated behavior.

In this study, we demonstrate that manipulations of temperature and free calcium alter the morphology of the centrin-containing pericentriolar lattice of PtK2 cells. Immunofluorescence microscopy reveals that low-temperature incubation (4 degrees C) causes anti-centrin-labeled pericentrosomal spots to coalesce in the peripheral cytoplasm, and fuses small spots into larger spots near the cell center. At electron microscopic resolution, well-formed pericentriolar satellites appear around the centrioles in response to incubation at 4 degrees C. Elevated free calcium enhances these low-temperature-dependent effects. The data suggest that pericentrosomal spots correspond to one or more pericentriolar satellites, and that pericentriolar satellites and centrosomal matrix are interconvertable forms of the same material. Transient elevation of intracellular free calcium at 37 degrees C from a basal level of 3.7 x 10(-8) M to a peak level of 2.0 x 10(-7) M within 30 seconds with ionomycin results in a 35% increase in pericentrosomal spot number throughout the cytoplasm. The number of pericentrosomal spots is 50% larger 2 minutes after ionomycin addition; these spots are also nearer to the cell center as compared to 30 seconds after ionomycin addition. As intracellular free calcium returns to a basal level over 5 minutes, the number of spots and their cellular distribution resume a pretreatment value and pattern. We interpret these observations to indicate movement of pericentrosomal spots toward the cell center in response to the flux in intracellular free calcium. Alternatively, it is possible that no movement has occurred, but that the rise in free calcium has unmasked an epitope responsive to our anti-centrin antiserum. Regardless of the interpretation, we conclude that the pericentriolar lattice exhibits calcium-modulated behavior.

Animals↗
PubMed1993

Disturbances of gingival fibroblast population homeostasis due to experimentally induced inflammation in the cynomolgus monkey (Macaca fascicularis): potential mechanism of disease progression.

We have studied the relationship between perturbations of fibroblast turnover in inflamed gingiva of different severities. To perform detailed spatial analyses of gingival fibroblast progenitor cells, inflammatory cell infiltrates and blood vessels, 3 Cynomolgus monkeys with healthy periodontium and 2 with naturally occurring gingivitis and ligature-induced periodontitis were pulse-labeled with 3H-thymidine. Morphometric analyses of radioautographs from mid-sagittal supra-alveolar gingival connective tissues of incisors were performed in sites subjacent to junctional sulcular and oral epithelium, in the body of the lamina propria and just superior to the alveolar crest. The percentage of fibroblasts incorporating 3H-thymidine label, expressed as the labeling index (LI), was higher subjacent to the sulcular epithelium in periodontitis (1.73 +/- 0.37) than in healthy sites (1.06 +/- 0.22). This was not statistically significant (0.05 < p < 0.1) due to the small number of animals used. The sites subjacent to the sulcular epithelium also exhibited the largest increase in lymphocyte density from health to gingivitis (p < 0.01). In contrast, the LI of fibroblasts subjacent to the oral epithelium was 5-fold higher in healthy (0.82 +/- 0.17) compared to periodontitis sites (0.13 +/- 0.09; p < 0.05). Labeled fibroblasts were found close to blood vessels in all compartments and in all disease states; distance to blood vessels was reduced in inflamed sites (p < 0.10). There were increased numbers of blood vessels per unit area in the lamina propria of gingivitis compared to healthy sites. However, there were no regional differences with respect to blood vessel numbers or area in sites subjacent to junctional epithelium with different disease states. The results indicate that: 1) experimentally-induced inflammation in the gingiva of Cynomolgus monkeys is associated with site-specific perturbations of cell turnover; 2) fibroblast progenitors are preferentially situated adjacent to blood vessels as in the periodontal ligament; 3) the vascular response to inflammation is a generalized increase in blood vessel numbers, but not their size; 4) reactive proliferation of fibroblasts may compensate for cell death in the lamina propria but is not detectable at the site of connective tissue attachment loss subjacent to the junctional epithelium. Failure to maintain the fibroblast progenitor population may be an important component of attachment loss in progressive periodontitis lesions.

Animals↗
PubMed1991

Central auditory skills in blind and sighted subjects.

Three different central auditory skills were compared and evaluated in 56 blind and 40 sighted subjects. The study consisted of three experiments conducted in three subgroups. Experiment A was performed in order to evaluate the localization function; experiment B for the temporal auditory resolution ability of the blind adult, and experiment C to test the ability of the blind person to discriminate speech material in noise. In all three experiments the blind subjects obtained significantly better results than the sighted subjects. From these results it was concluded that there is supporting evidence of a certain superiority of the blind individual with regard to central auditory function.

Adolescent↗
PubMed1989

Coordinated regulation of endothelial and fibroblast cell proliferation and matrix synthesis in periodontal ligament adjacent to appositional and resorptive bone surfaces.

Little is known about the remodeling of blood vessels and soft connective tissue or the proliferation of endothelial cells in the periodontal ligament (PL) of teeth undergoing physiological drift. To determine whether there is evidence for coordinated regulation of endothelial cell and fibroblast proliferation and matrix synthesis in sites within the PL adjacent to bone-appositional (A) and bone-resorptive (R) surfaces, the PL in mouse mandibular molar was subdivided into A and R sectors on the basis of 3H-proline incorporation into alveolar bone. Computer-assisted morphometry of radioautographs showed that the number and area of blood vessels were similar in A and R sectors. Proliferation of endothelial cells and fibroblasts was assessed from radioautographs prepared from mice continuously labeled with 3H-thymidine at times between 2 and 60 days. Significantly more labeled endothelial cells (P less than .001) and fibroblasts (P less than .05) were seen in the A sector. The percent of labeled endothelial cells and the percent of labeled fibroblasts increased linearly to 25 days and then formed a plateau. The rate of increase of labeled fibroblasts was higher in the A sector than in the R sector (P less than .025). In addition, 3H-proline grain counts over extracellular matrix were significantly higher in the appositional sector than in the resorptive sector (P less than .025).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Paravascular cells in endosteal spaces of alveolar bone contribute to periodontal ligament cell populations.

Endosteal spaces of alveolar bone communicate with the periodontal ligament and may contribute to its cell populations. We examined cell proliferation and migration in endosteal spaces and in the periodontal ligament contiguous with these spaces. Radioautographs of mouse mandibular molar were prepared from animals pulse-injected with 3H-Tdr and sacrificed in groups of 22 mice each at 1 h, 1, 3, and 7 d after labeling. Cell counts, labeling indices, grain counts, and progenitor cell ratios were determined. The data indicate that endosteal spaces are enriched with 3H-Tdr-labeled progenitor cells whose progeny rapidly migrate out of the compartment. The periodontal ligament contiguous with the endosteal spaces exhibited 5 times as many labeled cells as other sites in this tissue. Thickened areas of cementum were coincident with the openings of endosteal spaces in over 64% of observations. The data are consistent with the hypothesis that cells migrate from endosteal spaces into the periodontal ligament and there express the phenotype for osteoblasts or cementoblasts.

Alveolar Process↗