Biomedical subjects

Z Tóth

Publications and source records attributed to Z Tóth.

At least 19 recordsLinked to original sources

PubMed2005

Novel calretinin and reelin expressing neuronal population includes Cajal-Retzius-type cells in the neocortex of adult pigs.

Cajal-Retzius cells and their secreted product reelin are essential for the lamination of the cerebral cortex. In all species studied to date Cajal-Retzius cells form a transient neuronal population that almost completely disappears from the neocortex postnatally. Recently, in the hippocampal formation of adult domestic pig, we have found a large calretinin- and reelin-immunoreactive cell population that morphologically corresponded to Cajal-Retzius cells. In the present study, we examined calretinin- and reelin-immunoreactive neurons in layer I of the prefrontal, temporal, parietal and occipital neocortical areas of newborn, young adult and adult domestic pigs. Large numbers of bipolar or fusiform calretinin-positive cells were found in the upper half of layer I in all examined age groups. The morphology of these neurons resembled that of the Cajal-Retzius cells. Layer I was occupied by a dense calretinin-positive axonal plexus that was similar to the previously described axons of Cajal-Retzius cells in other species. In a similar location, where calretinin-positive cells occurred in layer I, large numbers of reelin-immunoreactive cells were found in all examined age groups. In addition, reelin colocalized with calretinin in layer I neurons. The number of calretinin and reelin-positive neurons decreased from 1 day to one year, but calretinin-positive Cajal-Retzius-type cells still comprised a remarkable large population in 12-month-old animals. Correlated light and electron microscopic examination of calretinin-labeled Cajal-Retzius-type cells indicated that these cells are integrated in the synaptic circuitry of the neocortex. Our results suggest that Cajal-Retzius cells do not disappear inevitably from the mature neocortex in all mammalian species. The function of this cell type is not known, but late persisting Cajal-Retzius-type cells in the domestic pig provide an opportunity to study their neuronal connections and the possible role of reelin in plasticity and regeneration of neocortex.

Aging↗

PubMed2005

Aortic cannulation and cardiopulmonary bypass independently produce selective brain lesions in pig.

Whether cardiopulmonary bypass alone or together with the manipulation of the aorta produce neurological complication remains controversial. Using a domestic pig model of cardiopulmonary bypass, we investigated the immediate effects of aortic cannulation and cardiopulmonary bypass on neuronal injury in different brain regions. We compared the presence of neuronal injury in three experimental groups: non-operated controls (n = 3); operated controls with aortic cannulation without cardiopulmonary bypass (n = 5); operated animals undergoing cardiopulmonary bypass (n = 5). Pyknotic cells were counted in the prefrontal cortex, cerebellum and in the hippocampal formation. Calretinin immunohistochemistry was used to show possible ischemic damages in the hippocampus which is known to be one of the most sensitive brain regions to ischemia. Decreased calretinin immunoreaction and reduced number of calretinin-positive neurons were observed in the hippocampal dentate gyrus following aortic cannulation or cardiopulmonary bypass compared to the non-operated control group. Changes were more severe following cardiopulmonary bypass than after cannulation of the aorta alone. The frequency of pyknotic cell nuclei was not different in the control and experimental groups. Our experimental study suggests that both cannulation of the aorta alone and cardiopulmonary bypass affect a selected population of neurons.

Animals↗

PubMed2003

Surface modifications induced by ns and sub-ps excimer laser pulses on titanium implant material.

Medical implants used in oral and orthopaedic surgery are mainly produced from titanium. Their biological behaviour, e.g. osseointegration, essentially depends on both the chemical composition and the morphology of the surface. Modifications achieved by excimer laser irradiation of titanium samples were investigated in order to improve their surface characteristics so as to facilitate biointegration. To enlarge the effective interfacial area of bone-implant contact, holes were ablated by laser pulses of ns or sub-ps length. During ns ablation, crown-like projecting rims formed around the borders of the holes. Ultra-short (0.5ps) KrF excimer laser pulses were successfully applied to avoid these undesirable formations. Since a smooth dental implant surface is necessary to maintain a healthy connection with the soft tissues, laser polishing of samples was investigated, too. Irradiation with a series of ns laser pulses resulted in effective smoothing, as measured with atomic force microscope. X-ray photoelectron spectroscopy analysis of the laser-polished titanium surface revealed that laser treatment led to a decrease of the surface contamination and in thickening of the oxide layer. X-ray diffraction measurements demonstrated that the original alpha-titanium crystal structure was preserved.

Biocompatible Materials↗

PubMed2003

Role of hypothalamic inputs in maintaining pituitary-adrenal responsiveness in repeated restraint.

The role of hypothalamic structures in the regulation of chronic stress responses was studied by lesioning the mediobasal hypothalamus or the paraventricular nucleus of hypothalamus (PVH). Rats were acutely (60 min) and/or repeatedly (for 7 days) restrained. In controls, a single restraint elevated the plasma adrenocorticotropin (ACTH), corticosterone, and prolactin levels. Repeated restraint produced all signs of chronic stress, including decreased body and thymus weights, increased adrenal weight, basal corticosterone levels, and proopiomelanocortin (POMC) mRNA expression in the anterior pituitary. Some adaptation to repeated restraint of the ACTH response, but not of other hormonal responses, was seen. Lesioning of the mediobasal hypothalamus abolished the hormonal response and POMC mRNA activation to acute and/or repeated restraint, suggesting that the hypothalamo-pituitary-adrenal axis activation during repeated restraint is centrally driven. PVH lesion inhibited the ACTH and corticosterone rise to the first restraint by approximately 50%. In repeatedly restrained rats with PVH lesion, the ACTH response to the last restraint was reduced almost to basal control levels, and the elevation of POMC mRNA level was prevented. PVH seems to be important for the repeated restraint-induced ACTH and POMC mRNA stimulation, but it appears to partially mediate other restraint-induced hormonal changes.

Adrenal Glands↗

PubMed2003

Effects of structural modifications of N-CPM-normorphine derivatives on agonist and antagonist activities in isolated organs.

The agonistic and antagonistic properties of N-cyclopropylmethyl (N-CPM) morphine derivatives were observed in mouse vas deferens (MVD), longitudinal muscle of guinea pig ileum (GPI) and rabbit vas deferens (LVD). In MVD the K(e) values of the titled compounds (N-CPM-morphine, N-CPM-isomorphine, N-CPM-dihydromorphine, N-CPM-dihydroisomorpPhine, N-CPM-dihydromorphone and naltrexone) were measured for mu-, kappa- and delta-receptors using normorphine, ethylketocyclazocine (EKC) and D-Pen2-D-Pen5-enkephaline (DPDPE) as selective agonists on the receptors, respectively. For mu-receptors of MVD the tested compounds showed similar affinity. For kappa-receptors the non-iso-6-OH derivatives possessed much less affinity than the iso-derivatives. Similar difference could be observed for delta-receptors. The agonistic activities of these compounds in MVD were observed to be between 0-20% of the inhibition of muscle contractions. In GPI the compounds except naltrexone possessed strong agonistic activities effectively antagonized by nor-binaltorphimine (nor-BNI) (K(e) of nor-BNI was 0.23 nM) suggesting that they were strong kappa-receptor agonists. We investigated these agents in LVD too, which contains kappa-receptors, but they did not produce any agonist potencies. It raises the possibility that the kappa-receptor subtypes of LVD and MVD are different from the kappa-receptor subtype of GPI or the vasa deferentia contain much fewer kappa-receptors than GPI and the intrinsic activities of these compounds are too small to reach the 50% inhibition of the contractions.

Animals↗

PubMed2002

Breath holding test in preeclampsia: lack of evidence for altered cerebral vascular reactivity.

Twenty-five healthy and thirty-one preeclamptic pregnant women were assessed by means of transcranial Doppler sonography. Resting cerebral blood flow velocities in the middle cerebral arteries were measured followed by a repeat measurement 30 s after breath holding. Absolute blood flow velocities and per cent changes after breath holding procedure were compared between the groups. Absolute blood flow velocities were higher in preeclamptic pregnant women both at rest and after breath holding. The percent increase in cerebral blood flow velocity after breath holding (cerebral vascular reactivity) was similar in the two groups. Our data suggest that cerebral vascular reactivity is preserved in pregnant women with preeclampsia.

Journal Article↗

PubMed2002

Idiopathic myelofibrosis with prominent postsplenectomy erythroblastosis terminating in acute myeloid transformation.

Idiopathic myelofibrosis is a myeloproliferative disease with poor prognosis and without sufficient therapy. Acute leukemic transformation occurs in 15% of patients. The authors report the case of a 63 year old myelofibrotic patient treated with splenectomy. During the clinical course they observed unusually prominent and persistent erythroblastosis in the peripherial blood. After a two years long, relatively stable period the disease terminated in acute myeloid leukemia.

Acute Disease↗

PubMed2001

[The role of uterine and umbilical artery Doppler velocimetry for the early detection of pathologic pregnancy].

Pregnancy induced hypertension remains the most frequent reason of maternal and fetal complications. Recent studies of the entire pathophysiology of the abnormal implantation proved association between the impaired placental performance and the reduced uteroplacental circulation. Therefore the Doppler examination of uterine and umbilical blood flow may provide the early recognition of high-risk pregnancies complicated by maternal hypertension and fetal intrauterine growth retardation. The authors endeavor to describe the details and characteristics of uteroplacental haemodynamic changes during the course of physiologic and defective implantation. On the basis of the currently available scientific publications they summarize the role of the uterine and umbilical artery Doppler velocimetry as a screening tool in the detection of the consequences of the impaired uteroplacental perfusion. They conclude that abnormal velocity waveforms obtained from the uterine and umbilical arteries may help to improve the efficacy of the prenatal care and the perinatal outcome as well. The clinical benefits of this screening method will be precisely defined on the basis of further multicenter studies in Hungary.

Arteries↗

PubMed2001

[Reproducibility of the laser fluorescence method for the diagnosis of occlusal caries. Clinical study].

The aim of the study was to assess the reproducibility of recently developed laser fluorescence method for occlusal caries detection in vivo. 71 non-cavitated premolar and molar teeth were examined repeatedly by three dentists using DIAGNOdent (KaVo) instrument. The presence of caries has been established on the classification of Lussi, created on the basis of "in vitro" investigations. The reproducibility of the measurements were expressed in rank correlation of Spearman. The intra- and interexaminer reliability was also determined by Kappa statistics. The Spearman correlation coefficiencies were fairly high (0.738-0.949) The intraobserver and interobserver coincidencies reflected by Kappa values (0.60-0.88 and 0.44-0.77, respectively) were also convincing.

Dental Caries↗

PubMed2001

[Dental implantation at the maxilla with autologous bone transplantation].

In the Department of Maxillofacial and Oral Surgery of County Hospital of Szentes, different types of bone losses of the maxillary alveolar ridge have been treated since 1 March, 1990. The applied surgical procedures were the following: 1. 394 patients were treated with GBR technique and 567 DenTi implants were inserted for these patients. 2. In 47 cases autogenous bone grafts were harvested from mandibular cortica and 78 DenTi implants were placed. Altogether 14 implants were lost; the success rate was 97.81% in the period between 1 March, 1990 and 31 January, 2001. 3. The severely resorbed maxillary alveolar ridge was replaced by rigid autogenous bone graft harvested from the ilium or from tibia. The bone graft was fixed with implants to the recipient surface. This method was applied in 36 cases from 1 February, 1992 until 31 January, 2001. 147 DenTi implants were inserted and 7 of them were lost. The success rate was 97.28%. Our results have indicated that the dental implants had accelerated the remodelling process of the transplanted autogenous bone and the success rate of the simultaneously performed dental implants were comparable to that of the two stage procedures in which dental implants were inserted several weeks following bone grafting. Based on our long-term favourable clinical experience this technique has been proven to be an excellent method for correcting and replacing the lost maxillary alveolar ridges as well as the circumscribed alveolar bony defects.

Bone Remodeling↗

PubMed2000

3D reconstruction based on hard tissue microtome cross-section pictures in dentistry.

The aim of this study was to examine the accuracy of the computerized 3D surface analyzing and volume measuring method in dentistry. Two different types of test objects were used in the first part of the measurements. Each sample of the two groups was cross-sectioned using a hard tissue microtome. The sections were photographed on both sides and were projected on a graphical tablet and analyzed using a computer program. The measured and calculated parameters were compared. In the second part, 200 microm thick horizontal sections were prepared from 11 human incisor roots using the hard tissue microtome. This way, five sections were prepared from the apical 2 mm of each root. The effects of section thickness and number were modeled by decreasing the inclusion rate of the obtained number of sections from 10 to 2 and its influence on the calculated results was determined. This method was suitable for the approximation and analysis of 3D parameters. The results indicated that using 200-300 microm section thickness, the measured values were approximately 8-21% lower than the real parameters.

Analysis of Variance↗

PubMed2000

[Some depth-psychological aspects of the psychogenic symptoms of oro-facial tissues].

The specificity of the oral psychogenic manifestations is based on the unique psychological and depth-psychological function of the mouth, and teeth during infancy (breasting), sexuality, and aggressivity. Fixed dentures, implants, and especially removable dentures can modify strongly these psychological functions and activate oral fixations leading to psychogenic symptoms. In the present paper the great importance of the oral phase of the development of personality and the symbolical values of the mouth, teeth, tongue, and face in the oro-facial conversive symptom manifestations are discussed.

Adult↗

PubMed1998

Quality assurance in obstetric and gynecologic ultrasound. The Hungarian model.

The majority of physicians performing obstetric scans are radiologists and obstetricians. The radiologist is well trained in imaging but lacks the obstetric background required to interpret information obtained from the scan. The obstetrician is qualified in obstetric knowledge but often lacks the formal imaging training necessary to optimize the pictures. In Hungary, nearly 100% of the physicians who perform obstetric and gynecologic scans are obstetricians. In order to create a standard and to hold together the practitioners in obstetrics and gynecology, as well as to eliminate the serious consequences of clinical malpractice, we organized the Hungarian Society of Ultrasound in Obstetrics and Gynecology in 1992. The Society was established according to the standards of the most skilled obstetricians and gynecologists. In addition to working out the conditions and the standards, the Society provides for its members continuous education, postgraduate training, and monitors the knowledge and level of practitioners. We have established three levels of qualification. Each level requires a medical undergraduate degree. The levels range from basic (A), intermediate (B), to specialist (C). To receive the certificate every user and ultrasound laboratory have to fulfill requirements based on skill as well as equipment and circumstances. The certificates are valid for one year. Every year the practitioner must pass a special examination at the appropriate level. By doing so, the Society provides its members with not only professional support, but ethical and legal security as well.

Certification↗

PubMed1998

Biclonal primary plasma cell leukemia.

Authors present a multiparameter pathological study in a case of rapid biclonal primary plasma cell leukemia. The immunohistochemical data revealed aberrant phenotypes (monocyte, epithelial and T-cell) probably in connection with microenvironmental influences. Biclonality can be attributed to class switching during malignant transformation. Static image cytometry showed aneuploidy. The blasts of this process are active immunoregulatory cells.

Adult↗

PubMed1998

Alterations in corticotropin-releasing hormone gene expression of central amygdaloid neurons following long-term paraventricular lesions and adrenalectomy.

Corticotropin-releasing hormone messenger RNA expression in the amygdala of rats after adrenalectomy and bilateral lesions of the hypothalamic paraventricular nucleus was examined by in situ hybridization histochemistry. Corticotropin-releasing hormone messenger RNA-containing cells are abundant in the intermediate subdivision of the central amygdaloid nucleus. Some corticotropin-releasing hormone-labeled cells are scattered in other subdivisions of the central nucleus and throughout the anterior amygdaloid area. Five days after bilateral adrenalectomy, the number of corticotropin-releasing hormone messenger RNA-containing cells was reduced both in the central nucleus and the anterior area of the amygdala. This reduction was prevented by corticosterone replacement and contrasts sharply with the known rise of corticotropin-releasing hormone messenger RNA in the paraventricular nucleus after adrenalectomy. Corticotropin-releasing hormone messenger RNA expression in the amygdala was up-regulated in rats with six-week bilateral lesions of the paraventricular nucleus. This elevation in corticotropin-releasing hormone messenger RNA was not influenced by adrenalectomy or corticosterone, and it did not correlate with plasma levels of adrenocorticotrophic hormone or corticosterone. The possible direct innervation of the amygdala by the paraventricular nucleus is supported by the demonstration of labeled axons from the paraventricular nucleus to the amygdala after injection of an anterograde tracer, Phaseolus vulgaris leucoagglutinin, into the paraventricular nucleus. Labeled fibers take two courses: through the lateral hypothalamus ventral amygdalofugal path and through the stria terminalis. Data presented here suggest that the paraventricular nucleus-amygdala connection is likely to be inhibitory to corticotropin-releasing hormone neurons in the central amygdala. These neurons may participate in behavioral responses to stress effected through brainstem autonomic centers rather than directly through the hypothalamo-pituitary adrenal axis.

Adrenalectomy↗

PubMed1997

Ventriculomegaly with radial and renal defects: prenatal diagnosis in two consecutive sibs.

We describe two consecutive mid-trimester fetuses of different sexes with identical anomalies of the upper limbs and the kidneys in association with severe ventriculomegaly. We compare this apparently autosomal recessive syndrome to VACTERL-H association, Fanconi anemia, and two other, so far unparalleled syndromes. Taking into account the absence of chromosome breaks, the associated changes of the amniotic fluid, and the renal histology, we conclude that we are dealing with a different entity.

Adult↗

PubMed1997

[Use of erythropoietin in pregnancy: review of the literature in connection with 2 cases].

Recently a growing number of case reports has been published about successful pregnancy outcome of dialysed women on recombinant human erythropoietin therapy. During pregnancy the maternal demand for erythropoietin may undergo changes, with consideration of recombinant human erythropoietin therapy in the early stage of renal insufficiency, as is shown by our two reported cases. The use of recombinant human erythropoietin seems to be safe for the foetus: it does not cross the placental barrier, and therefore lacks any direct foetal effect. The treatment of anaemia with recombinant human erythropoietin carries benefits for both the mother and foetus. One of the most important preconditions for successful recombinant human erythropoietin therapy is adequate iron supplementation. Due to the increased risk of pregnancy induced hypertension or preeclampsia, there is a need for slow and gradual correction of anaemia, and an individually tailored target hematocrit. A close follow up of he patient by the obstetrical-nephrological team is essential, with the intensive monitoring of the fetuses. In some cases with normal renal function the stimulation of erythropoiesis with recombinant human erythropoietin may also be needed during the pregnancy.

Acute Kidney Injury↗

PubMed1997

Conformationally constrained deltorphin analogs with 2-aminotetralin-2-carboxylic acid in position 3.

Two approaches to the design of very active and highly selective delta opioid peptides were used to obtain new deltorpin analogs with altered hydrophobic and stereoelectronic properties. Deltorphin I and II analogs were synthesized involving the substitution of Ile instead of Val at positions 5 and 6 in the address domain and 2-aminotetralin-2-carboxylic acid (Atc) instead of Phe in the message domain. The peptides were agonists in the subnanomolar range in the MVD assay and in the micromolar or higher range in the GPI assay, showing a very high selectivity for delta receptors. A very similar trend could be observed in radioreceptor binding assays in which selective tritiated opioid ligands were used. (R)- and (S)-Atc-deltoriphins exhibited similar Ki values in the binding assay, with almost complete loss of the stereospecificity of the binding. Conformational studies provided evidence for the little disturbance of the backbone conformational equilibrium when Phe3 is replaced by (S)- or (R)-Atc. The use of the Atc constraint gives additional evidence that, during its interaction with the delta receptor, the side chain of residue 3 adopts the trans conformation at chi 1.

Analgesics, Opioid↗