Biomedical subjects

P Nagy

Publications and source records attributed to P Nagy.

At least 55 records · Page 3Linked to original sources

PubMed1999

Complexity of signal transduction mediated by ErbB2: clues to the potential of receptor-targeted cancer therapy.

The erbB2 oncogene belongs to the type I trans-membrane tyrosine kinase family of receptors. Its medical importance stems from its widespread over-expression in breast cancer. This review will focus on the signal transduction through this protein, and explains how the overexpression of erbB2 may result in poor prognosis of breast cancer, and finally it will summerize our current understanding about the therapeutic potential of receptor-targeted therapy in breast cancer. ErbB2 does not have any known ligand which is able to bind to it with high affinity. However the kinase activity of erbB2 can be activated without any ligand, if it is overexpressed, and by heteroassociation with other members of the erbB family (erbB1 or epidermal growth factor receptor, erbB3 and erbB4). This interaction substantially increases the efficiency and diversity of signal transduction through these receptor complexes. In addition, erbB2 forms large scale receptor clusters containing hundreds of proteins. These receptor islands may take part in recruiting cytosolic factors which relay the signal towards the nucleus or the cytoplasm. Overexpression of erbB2 was linked to higher transforming activity, increased metastatic potential, angiogenesis and drug resistence of breast tumor in laboratory experiments. As a corollary of these properties, erbB2 amplification is generally thought to be associated with a poor prognosis in breast cancer patients. These early findings lead to the development of antibodies that down-regulate erbB2. Such a therapeutic approach has already been found effective in experimental tumor models and in clinical trials as well. Further understanding of the importance of erbB2 and growth factor receptors in the transformation of normal cells to malignant ones may once give us a chance to cure erbB2 over-expressing breast cancer.

Animals↗

PubMed1999

Activation-dependent clustering of the erbB2 receptor tyrosine kinase detected by scanning near-field optical microscopy.

ErbB2 (HER2, Neu), a member of the epidermal growth factor (EGF) receptor tyrosine kinase family, is often overexpressed in breast cancer and other malignancies. ErbB2 homodimerizes but also presents as a common auxiliary subunit of the EGF and heregulin receptors (erbB1 or EGFR; and erbB3-4, respectively), with which it heteroassociates. ErbB2 is generally regarded as an orphan (ligand-less) receptor with a very potent kinase domain activated either via its associated partners or constitutively as a consequence of discrete mutations. It follows that the extent and regulation of its cell surface interactions are of central importance. We have studied the large-scale association pattern of erbB2 in quiescent and activated cells labeled with fluorescent anti-erbB2 monoclonal antibodies using scanning near-field optical microscopy (SNOM). ErbB2 was found to be concentrated in irregular membrane patches with a mean diameter of approx. 0.5 microm in nonactivated SKBR3 and MDA453 human breast tumor cells. The average number of erbB2 proteins in a single cluster on nonactivated SKBR3 cells was about 10(3). Activation of SKBR3 cells with EGF, heregulin as well as a partially agonistic anti-erbB2 monoclonal antibody led to an increase in the mean cluster diameter to 0.6-0.9 microm, irrespective of the ligand. The EGF-induced increase in the erbB2 cluster size was inhibited by the EGFR-specific tyrosine kinase inhibitor PD153035. The average size of erbB2 clusters on the erbB2-transfected line of CHO cells (CB2) was similar to that of activated SKBR3 cells, a finding correlated with the increased base-line tyrosine phosphorylation of erbB2 in cells expressing only erbB2. We conclude that an increase in cluster size may constitute a general phenomenon in the activation of erbB2.

Animals↗

PubMed1998

[Current data on familial occurrence of malignant hematologic diseases in the County of Szabolcs-Szatmár-Bereg in Hungary].

So far the authors have observed 27 cases of accumulation of malignant haematologic diseases within a family in their county. They published the first ten cases in Orvosi Hetilap in 1992. Most often the co-existence of the diseases with the highest incidence (non-Hodgkin's lymphoma, chronic lymphocytic leukaemia, acute leukaemia) was observed, in terms of relationship mostly the parent--child combination was observed. Analyzing the data of parent--child combinations (17 cases) they can notice two remarkable trends: 1. The "malignity degree" of the disease appearing in the second generation is either the same or greater than that of the disease of the first generation (the opposite of this was not experienced in any of the cases!). 2. The disease of the second generation appears mostly at a much younger age than that of the parent. Consequently, they can observe a "double acceleration": the disease tends to be more malignant nearly in the half of the second generation patients, and the disease appears in the children at a much younger age.

Adolescent↗

PubMed1998

Expression of transforming growth factor-alpha in hepatoblastoma.

BACKGROUND: Transforming growth factor-alpha (TGF-alpha) is a potent stimulator of cell proliferation in the liver and in liver tumors; however, its significance and association with hepatocyte proliferation remains unclear. METHODS: Expression of TGF-alpha and proliferation markers, such as proliferating cell nuclear antigen (PCNA) and cyclin A, were studied and correlated with each other in samples of tumor and surrounding liver tissue taken from nine patients with hepatoblastoma. An avidin-biotin-peroxidase immunohistochemical method was used for detection of TGF-alpha, PCNA, and cyclin A, and in situ hybridization was used to detect TGF-alpha mRNA. RESULTS: Two types of tumor cells of epithelial origin were distinguished based on the expression of TGF-alpha protein and RNA. The more differentiated "fetal" phenotype had a high expression of TGF-alpha and correlated with a low expression of proliferation markers. The less differentiated "embryonal" phenotype had low TGF-alpha expression and high proliferation activity. CONCLUSIONS: The expression of TGF-alpha is associated with a certain morphologic phenotype of tumor cells in hepatoblastoma; higher expression can be detected in more differentiated tumor cells. The negative correlation between the expression of TGF-alpha and proliferation markers suggests that the less differentiated embryonal cells do not depend on growth stimulation provided by TGF-alpha.

Cell Division↗

PubMed1998

EGF-induced redistribution of erbB2 on breast tumor cells: flow and image cytometric energy transfer measurements.

erbB2, a member of the epidermal growth factor (EGF) receptor-type tyrosine kinase receptor family, is overexpressed in breast carcinomas with poor prognosis. We examined the cell surface association of this receptor with itself and with other cell surface proteins by the Förster-type fluorescence resonance energy transfer using whole antibodies and Fab fragments. We found that erbB2 molecules homoassociate in unstimulated SK-BR-3, BT474 and BT474-M (a metastatic version of the parent BT474 line) breast tumor cells, and that the interaction was enhanced by EGF treatment in suspensions of SK-BR-3 and BT474-M cells. BT474 cells (with low EGF receptor expression) and attached SK-BR-3 cells do not respond to EGF. Image microscopic energy transfer measurements found considerable pixel-by-pixel heterogeneity in the homoassociation state of erbB2. In accordance with the EGF-induced redistribution of erbB2, EGF receptor was found to be in close proximity to erbB2 in FRET measurements. By labeling different epitopes on erbB2 and the lipid bilayer, we were able to prepare an epitope map of erbB2 molecule. Our data suggest the existence of dynamic cell surface patterns of erbB2 and point to functions fulfilled by these molecular complexes.

Breast Neoplasms↗

PubMed1998

[Determination of the upper margin of superficial esophageal cancer by intraoperative endoscopic examination and toluidine blue staining].

Authors describe a new application of intraoperative endoscopic examination. At operation it is difficult to define the border of a superficial esophageal cancer. The female patient aged 69 years was operated on because of squamous cell cancer. During the operation endoscopic examination was done and the esophageal mucosa was stained with 1% toluidine blue solution. The squamous cancer stained blue. The upper border ot the tumour was determined so that the esophageal wall was palpated from the outside with a probe and the same time the manipulation was being watched on the monitor of the videoendoscope. Subtotal esophagectomy and lymphadenectomy were performed. Authors claim that by the intraoperative use of endoscopic staining the risk recurrence in an anastomosis may be diminished and leaving behind of multifocal carcinoma may be eliminated.

Aged↗

PubMed1998

Dexamethasone inhibits the proliferation of hepatocytes and oval cells but not bile duct cells in rat liver.

Recent advances have implicated the importance of tumor necrosis factor (TNF) and interleukin 6 (IL-6) in the regulation of liver growth. Therefore, we studied how dexamethasone, a well-known inhibitor of these cytokines, influences the proliferation of different hepatic cell populations. As we expected, dexamethasone pretreatment suppressed the expression of both TNF and IL-6 after partial hepatectomy and significantly reduced the proliferative response of the hepatocytes. Furthermore, the proliferative response of hepatocytes could be rescued by IL-6 administration. Dexamethasone also severely diminished the induction and expansion of oval cells induced by the 2-acetylaminofluorene/partial hepatectomy (AAF/PH) protocol but did not have any effect on the proliferation of the bile duct cells stimulated by bile duct ligation. The differential inhibition of these two morphologically very similar cell types may be used to characterize divergent regulatory mechanisms responsible for the proliferative response of oval cells and adult bile epithelial cells.

Animals↗

PubMed1998

Intensity-based energy transfer measurements in digital imaging microscopy.

Investigation of protein-protein associations is important in understanding structure and function relationships in living cells. Using Förster-type resonance energy transfer between donor and acceptor labeled monoclonal antibodies we can assess the cell surface topology of membrane proteins against which the antibodies were raised. In our current work we elaborated a quantitative image microscopic technique based on the measurement of fluorescence intensities to calculate the energy transfer efficiency on a pixel-by-pixel basis. We made use of the broad excitation and emission spectrum of cellular autofluorescence for background correction of images. In addition to the reference autofluorescence images (UV background) we recorded three fluorescent images (donor, acceptor and energy transfer signal) of donor-acceptor double labeled samples, and corrected for spectral spillage of the directly excited donor and acceptor fluorescence into the energy transfer image. After careful image registration we were able to calculate the energy transfer efficiency on a pixel-by -pixel basis. In this paper, we also present a critical comparison between results obtained with this method and other approaches (photobleaching and flow cytometric energy transfer measurements).

Antibodies, Monoclonal↗

PubMed1998

Factors influencing ovarian activity and sexual behavior of postpartum mares under farm conditions.

Management of the postpartum period is one of the most important factors of stud farm medicine. In horses, owing to the long gestation period, the time from parturition to repeat conception needs be short to maintain an optimal yearly foaling interval. For this reason the features of postpartum ovarian activity and sexual behavior were studied under farm conditions. During 2 consecutive breeding seasons, 107 mares on 5 commercial horse farms were monitored after parturition by regular teasing, transrectal ultrasonography and blood sampling for progesterone. Foalings took place from January 1 to June 15. Body condition scoring was carried out within 5 d and at 60 to 65 d after parturition. The first ovulation occurred within 20 d after foaling in 84.1% (90/107) of the mares. The mean intervals from foaling to the first and second ovulations were 17.8 +/- 1.6 d (+/- SEM) and 40.9 +/- 2.7 d (+/- SEM), respectively. The mean intervals from parturition to the first and second ovulation (P < 0.001), the interovulatory interval (P < 0.01), the second follicular phase (P < 0.001), and the time until the first overt estrus (P < 0.01) were significantly longer in mares foaling before the vernal equinox. In the beginning of the breeding season the intervals from parturition to the first ovulation (P < 0.01), to the second ovulation (P < 0.01), and to the first overt estrus (P < 0.001) were significantly longer for primiparous mares than for multiparous animals. There was a tendency for an increased interovulatory interval and for a longer second follicular phase in mares with decreased body condition after parturition (P = 0.069, P = 0.089, respectively). Suckling and breed had no effect on postpartum ovarian activity. We concluded that under field conditions the resumption of cyclic ovarian activity and sexual behavior in mares after foaling are strongly affected by the season of parturition and parity. In some cases, body condition change and other factors may also play a role in influencing postpartum reproductive function.

Animals↗

PubMed1998

Experimental and human liver fibrogenesis.

In this work, we provide an overview of our results obtained by studying the role of transforming growth factor beta1 and proteoglycans in liver fibrogenesis. It has been found that transforming growth factor beta1 is one of the most important stimulators of extracellular matrix synthesis in the liver. In chronic liver injury, desmin-positive non-parenchymal liver cells expressed transforming growth factor beta1. The extracellular localization of the growth factor correlated well with types I, III and IV procollagen-alpha, which were detected in the fibrous septa of chronically injured livers. A similar distribution pattern was observed in human specimens. To identify the role of transforming growth factor beta1 in liver extracellular matrix protein synthesis, transforming growth factor beta1-positive transgenic mice were generated. Animals expressing the growth factor in their liver showed spontaneous liver fibrosis. Proteoglycans also participate in fibrogenesis. The majority of liver-specific heparan sulfate proteoglycans, such as syndecan-1 and fibroglycan, are produced by hepatocytes. The extracellular matrix proteoglycans decorin and perlecan are synthesized by non-parenchymal liver cells. The amount of the latter is very low in normal liver, but increases dramatically in liver fibrosis. The effect of regulatory factors on liver proteoglycans seems to be cell type-specific. In contrast to previous observations, elevated amounts of decorin did not inhibit the action of transforming growth factor beta1 in the liver.

Animals↗

PubMed1998

Human and experimental hepatocarcinogenesis.

Human liver cancer is increasing worldwide, including in Hungary. The detection of liver tumors in premalignant or early malignant states is essential for successful treatment. MC-29 virus-induced chicken hepatoma and rodent, fish and monkey models for chemical hepatocarcinogenesis were studied and compared to humans. Changes in phenotypic enzyme alterations and in the expression of certain oncogens and growth factors characterize the experimentally induced hepatomas, and might also be characteristic of human premalignant and malignant focal liver lesions. Fish hepatocarcinogenesis is useful for studying compounds in environmental pollution. Increased expression of transforming growth factor á can be observed both in experimental and human liver tumors. Increased tumor incidence was detected in transgene mice containing both transforming growth factor alpha and c-myc genes. Animal models of hepatocarcinogenesis help to understand the development of liver tumors. Methods applied in studies using those models are useful in the study of premalignant and malignant human liver lesions.

Animals↗

PubMed1998

Results of intracytoplasmic sperm injection with ejaculated, fresh and frozen-thawed epididymal and testicular spermatozoa.

Over the past 5 years, intracytoplasmic sperm injection (ICSI) has been developed to alleviate severe long-standing andrological infertility in couples who could not be helped by standard in-vitro fertilization (IVF), or who could not undergo IVF because too few motile and morphologically normal spermatozoa were present in the ejaculate. ICSI can also be carried out with fresh and frozen-thawed epididymal spermatozoa from patients with obstructive azoospermia and with testicular spermatozoa from most patients with obstructive azoospermia and from some patients with non-obstructive azoospermia. This review reports the results of 5 years of ICSI practice (1991-1995) at the Brussels Free University Centre for Reproductive Medicine, including selection of patients, oocyte and spermatozoa for ICSI, ICSI procedures and its assessment. ICSI was performed in 97% of the 4688 planned treatment cycles. Ejaculated spermatozoa were used in 88% of the cycles, epididymal spermatozoa in 5% of the cycles and testicular spermatozoa in 7% of the cycles. ICSI was performed on 48393 metaphase II oocytes. Of these, 89.5% were morphologically intact, and 70.9% of the intact oocytes were normally fertilized; 64.9% of the two-pronuclear oocytes developed after a further 24 h of in-vitro culture into cleaved embryos, which were transferred or cryopreserved for subsequent use. After transfer of fresh embryos, the percentage of cycles with positive serum human chorionic gonadotrophin was 36.2% per transfer and the percentage of deliveries was 27.0% per transfer. The performance of ICSI with regard to damage, pronuclear status, embryo development and transfer was analysed separately for the four different types of spermatozoa used: fresh ejaculated, epididymal and testicular as well as frozen-thawed epididymal spermatozoa.

Cryopreservation↗

PubMed1998

Do we treat the male or his gamete?

The history of the male infertility patient is of utmost value. A physical examination is mandatory when psychosexual and ejaculatory dysfunction and male accessory gland infection are suspected, and even in the presence of azoospermia. It is also advisable to perform a physical examination to exclude the presence of testicular tumours. The diagnostic assessment includes sperm analysis, history, physical examination, the Valsalva manoeuvre, Doppler, ultrasonography, hormonal serum measurements, evaluation of testicular volume by orchidometry and evaluation of testicular consistency by palpation. The diagnosis of male infertility is descriptive and determination of true causality is almost non-existent. For decades, various therapies have been proposed to improve sperm parameters in cases of male factor infertility. Administration of anti-oestrogens and androgens is ineffective. No peer-review data are available to demonstrate the benefit of the use of intrauterine insemination or the correction of varicocele. Classic in-vitro fertilization is to some extent a solution for male factor infertility; however, the two-pronuclear fertilization rate for patients with impaired semen samples is significantly lower than that for patients with non-male indications. Conventional treatment for male factor infertility has little value and has been revised and abandoned. Intracytoplasmic sperm injection is an effective treatment, even for cases of extreme oligoasthenoteratozoospermia. It has to be considered the method of choice and should replace ineffective conventional therapies.

Estrogen Antagonists↗

PubMed1998

Clinical experience with preimplantation genetic diagnosis and intracytoplasmic sperm injection.

Preimplantation genetic diagnosis (PGD) is a novel procedure whose use may be considered to obtain a very early prenatal diagnosis for couples at risk for transmitting genetic diseases. Using the polymerase chain reaction (PCR) or fluorescence in-situ hybridization (FISH) the genotype or the sex of biopsied cleavage-stage embryos obtained after in-vitro fertilization can be determined and selected embryos can then be transferred. In-vitro fertilization with intracytoplasmic sperm injection is the method of choice to obtain embryos to be analysed through PCR to reduce contamination by residual sperm DNA. In our series of 61 PGD cycles for 29 couples at risk over a period of 4 years the ongoing pregnancy rate per cycle was 15%, per transfer 19% and per patient 31%. One of the six morphologically normal children born, who is still alive and doing well, weighed 850 g after birth at 25 weeks following a complicated triplet pregnancy. More experience is needed to correctly evaluate the efficiency and safety of this novel technique as well as to determine its place in the prevention of genetic disease.

Adult↗

PubMed1998

Modulation of the plasminogen activator/plasmin system in rat liver regenerating by recruitment of oval cells.

The proteolytic cascade involving plasminogen activators and plasmin appears to have an important function in tissue regeneration. We have investigated the expression and cellular localization of urokinase-type plasminogen activator (uPA), tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator receptor (uPAR), and plasminogen activator inhibitor-1 (PAI-1) as well as plasminogen activation in rat liver regeneration by recruitment of progenitor (oval) cells. Using a model in which surgical partial hepatectomy is combined with feeding of 2-acetylaminofluorene (2-AAF) to induce liver regeneration by proliferation and differentiation of oval cells, expression of uPA, uPAR, and PAI-1 was detected by immunohistochemistry mainly in the duct-like formations of expanding oval cells. Plasminogen activation, as assessed by direct zymography on frozen liver sections, was located over the expanding oval cell populations but not over mature hepatocytes. Plasminogen activation was not detected in control liver. Expression of uPA, uPAR, and PAI-1, as assessed by immunohistochemical and Northern blot analyses, was also observed, when cells located in and in close proximity to the bile epithelial structures were activated to enter DNA-synthesis in response to 2-AAF, and after in vivo infusion of various growth factors. Given the physiologic function of plasminogen activation in fibrinolysis, and plasminogen activators in activation of latent growth factors, the selective expression of the plasminogen activator/plasmin proteolytic cascade in oval cells expanding during liver regeneration in response to the combination of 2-AAF and partial hepatectomy, may confer a proliferative advantage to these cell populations in an extracellular matrix containing both fibrin and latent growth factors.

2-Acetylaminofluorene↗

PubMed1998

Progesterone determination in equine plasma using different immunoassays.

Several assay systems (3H radioimmunoassay (RIA) with and without extraction; microplate enzyme-linked immunoassay (ELISA); qualitative ELISA (tube test)] were used to measure plasma progesterone concentration in mare plasma. The direct RIA showed a close correlation (R = 0.94) with the extraction RIA. The direct RIA and the microplate ELISA were compared in two different studies. In the first study 1155 samples of postpartum mares were used for progesterone determination with both assays. The ELISA resulted in more elevated values both in oestrus and dioestrus (0.19+/-0.3 and 2.44+/-3.62 nmol/l for oestrus, n = 436, and 8.94+/-4.29 and 27.88+/-18.34 nmol/l for dioestrus, N = 719, for the RIA and ELISA, respectively, R = 0.71). The evaluation of individual progesterone profiles has revealed that the microplate ELISA detects the time of ovulation at the same time as it is determined by the RIA and clinical examination. The sensitivity and specificity were calculated for different progesterone threshold values. In the second study including 7 non-pregnant, cycling mares the progesterone concentration of 240 samples was determined by both assays. Basal values (Day 0) obtained with the ELISA were higher (1.57 nmol/l) than those of the RIA (0.2 nmol/l). Both curves reached the same maximum concentration (12.11 and 12.45 nmol/l) 5 days after ovulation. The correlation between the RIA and ELISA values was high (R = 0.90). The tube test was compared to the microplate ELISA as reference using 576 plasma samples of 34 non-pregnant, non-cycling mares included in an ovulation induction study. Of these samples 118 had higher and 458 had lower values than 3.18 nmol/l. In most cases the tube test was in complete agreement with the microplate ELISA. The sensitivity, specificity, + predictive and - predictive values for the tube test were 79.7%, 95.4%, 81.7% and 94.8%, respectively.

Animals↗

PubMed1997

[Synchronous surgical removal of esophageal and pulmonary cancer by endoscopic mucosectomy and video-assisted lobectomy through minimal thoracotomy].

Authors report a case of a 75 year old, male patient suffering from an early stage squamous esophageal cancer and a synchronous adenocarcinoma of the lung. The patient was operated on simultaneously at the same setting: the esophageal tumour was taken out by endoscopic mucosectomy, whereas the pulmonary cancer was removed by video assisted minimal thoracotomy. The definitive histological diagnosis was: squamous cell cancer (muscular mucosal cancer) (pT1) of the esophageal lesion and adenosquamous cancer (pT2) of the lung. Authors draw attention on the significance of the early diagnosis of malignant tumours, and in this case minimally invasive endoscopic procedures can be successfully performed.

Adenocarcinoma↗

PubMed1997

[Comparative analysis of diagnoses by the referring family physician and the hospital admission committee in ambulatory patients at an internal medicine department].

The objectives of the present study were, as follows: 1. To what rate do the primary care doctors refer their patients to the regional internal medicine emergency department? 2. What sort of problems are the reasons of the referring? 3. To what extent are the opinions of the referring doctors confirmed or reviewed by the specialists? 4. What rate of the referred patients are admitted or discharged after the urgent consultations and-or interventions. 5. What kind of additional tests were used by the institutional caregivers in order to make accurate diagnoses? 6. What was the fate of the unaccepted patients? Data were collected in the patient document archive of the First Dept. of Medicine of the Albert Szent-Györgyi Medical University, Szeged, Hungary. Each patients' referring notes and inpatient charts between September 15th, 1995 and January 15th, 1996 were studied in a retrospective way. Upon the results of the study, it was concluded, as follows: The primary care doctors referred their patients with right orientation diagnosis to the emergency department in 70% of the cases. 45.8% of the referred pts. were admitted to the internal inpatient ward. The agreement of the referring and discharge diagnoses was greater (85.7%) among the admitted patients as compared to the unaccepted ones (56.8%). 14% of the referred pts. were referred to other specialists by the internists. On the basis of the results the actual messages of the study for an under- and postgraduate medical teaching group, and for the health care politicians are discussed in the paper.

Ambulatory Care↗