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Biomedical subjects

L Takács

Publications and source records attributed to L Takács.

At least 19 recordsLinked to original sources

Thymocyte costimulating antigen is CD26 (dipeptidyl-peptidase IV). Costimulation of granulocyte, macrophage, and T lineage cell proliferation via CD26.

The rat thymocyte costimulating protein appears to be involved in the regulation of CD4-/CD8- thymocyte proliferation in vitro. We show that thymocyte costimulating protein is dipeptidyl peptidase IV (E.C.N.3.4.14.5) also known as CD26. Some bone marrow cells as well as CD4-/CD8- and, and to a lesser extent, more differentiated T cells respond by proliferating to a CD26 specific mAb-mediated costimulus that does not influence dipeptidyl dipeptidase IV enzyme activity. This suggests the existence of a CD26-linked regulatory mechanism of proliferation that is operational on granulocyte- and macrophage-lineage cells and throughout T cell development.

Animals

Characterization of a novel rat thymocyte costimulating antigen by the monoclonal antibody 1.3.

To define membrane-associated molecules that impart signals for the activation and expansion of double negative (DN) cells, mAb were raised against in vitro-cultured rat DN cells. One such mAb, 1.3, stimulated proliferation of DN cells along with submitogenic concentrations of PMA and IL-2 without affecting the mobilization of Ca2+. The 1.3 mAb precipitated a heterodimeric protein from DN cells and kidney (130/110 kDa). Although the tissue distribution and biochemical characteristics of the 1.3 determinant resemble the neutral aminopeptidase (AP-N) first described as the thymocyte activating molecule in the mouse, other data are contradictory; AP-N message was not detected in mRNA from 1.3 positive cells and the AP-N gene was absent in the genomic DNA from rat DN hybridomas expressing high levels of 1.3 Ag. In addition, the 1.3 mAb did not affect AP-N enzyme activity suggesting that 1.3 mAb does not function through this enzyme to transduce signals for proliferation. Thus, the 1.3 mAb defines a new and important thymocyte costimulating Ag.

Animals

CD3-induced T-cell proliferation and interleukin-2 secretion is modulated by the CD45 antigen.

In the present study we have investigated the effect of CD45, CD45RA and CD45RO monoclonal antibodies (MoAbs) on the CD3 receptor-mediated proliferation of human T lymphocytes. It is shown that CD3-induced proliferation of purified resting T cells and quiescent T lymphoblasts (QTL) is promoted via all of the investigated CD45-associated epitopes. It is also shown that the CD45 molecules are required to be cross-linked for costimulation. The MoAbs enhance the interleukin-2 (IL-2) production of CD3-stimulated QTL. The elevation of the IL-2 production correlates with the increase in CD3-induced cell proliferation suggesting that the CD45-driven regulation of T lymphocyte activation is linked to the IL-2 pathway.

Animals

[A computerized follow up system of obstetric and genetic care].

The authors have implemented and introduced a new filing system representing the complexity of obstetric, genetic and neonatal care for the three counties of the Eastern part of Hungary. Data about the pre-, peri- and postnatal management are supplied by the genetic/teratologic, obstetric, neonatal and pathological units and processed at the Department of Obstetrics and Gynaecology, University Medical School of Debrecen with an IBM compatible AT computer. This computerised registry is based on the personal identification number, so it is easy to handle for storing data about the course and outcome of a large number of pregnancies as well as the detection and follow-up of fetal malformations and genetic diseases. The computer register is suitable for easy and systematic storage of the more than 20 thousand pregnancies screened by both maternal serum AFP and ultrasound including nearly 500 prenatal diagnosis cases per year. When devising the system, the classic parameters of the "revised Tauffer statistics" have been taken into consideration, but the emphasis has been put mostly on the assessment of fetal/infantile health status and the prevention of malformations and genetic diseases. This computerised system greatly facilitates the correct assessment of statistical parameters in related medical fields and provides better possibilities for studying the cause and effect relationship between the efficacy of medical care and perinatal events.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Rate

Effect of free radicals in ischaemic renal failure in the dog.

After a 30-minute control period ischaemia was evoked in dogs under Nembutal (30 mg/kg, i.v.) anesthesia, by clamping the left renal artery for 45 minutes. This was followed by a 90-minute reperfusion period when diuresis, GFR, PAH clearance, sodium and potassium excretion, malondialdehyde level in the plasma of the renal vein and SOD enzyme activity of the erythrocytes in renal venous blood were determined. Besides the control group (n = 6), the following treated groups were investigated: 1. Allopurinol (n = 7) in a dose of 100 mg/kg, given orally for two days, 2. Silibinin (n = 6) in a dose of 4 mg/kg/hour, given into the renal artery, 3. MTDQ-DS (n = 6) in a dose of 150 mg/kg/hour, given intravenously. 4. SOD (n = 4) 4 mg infusion (initiated 1 minute prior reperfusion). In the first 15-minute period following reperfusion GFR was 21%, cPAH 29% and sodium and potassium excretion 67 and 42% of the values of the contralateral kidney, respectively. Renal function improved gradually during the 90 minutes of reperfusion, and the above-mentioned parameters reached 59, 57, 65 and 76% of the corresponding control data. Increase of malondialdehyde level in the venous blood of the kidney during reperfusion might have been indicative of the production of free radicals; the difference, however, was not significant statistically. The administrations did not lead to considerable change in any of the parameters investigated. No difference could be demonstrated by histological methods between the kidneys of the treated and untreated animals. The compounds studied are thought to be free radical scavengers; in the present work, however, no protective effect could be demonstrated.

Acute Kidney Injury

Effect of ventilation on sodium excretion in the anesthetized dog with unilateral renal denervation.

We studied if the effect of mechanical ventilation induced to keep arterial blood gas values within normal physiological limits has any influence on renal sodium excretion in anesthetized dogs (n = 17) subjected to acute unilateral renal denervation. Compared to the control and the postcontrol periods, ventilation elevated arterial pO2 from 86 +/- 5 to 96 +/- 5 mmHg and blood pH from 7.37 +/- 0.02 to 7.41 +/- 0.01 while arterial pCO2 was decreased from 38 +/- 2 to 33 +/- 1 mmHg (p less than 0.05 in all cases). Compared to the innervated kidney urine flow, urinary sodium and potassium excretion from the denervated kidney were markedly elevated both during spontaneous respiration and during mechanical ventilation but GFR and cPAH were similar on the two sides. Ventilation decreased sodium excretion by the denervated kidney from 314 +/- 26 to 252 +/- 31 mumols/min/100 g k. w. (p less than 0.05). No other excretory changes were noted either in the innervated or in the denervated kidneys. Difference in sodium excretion between innervated and denervated kidneys was decreased from 209 +/- 19 to 126 +/- 20 mumole/min/100 g k. w. (p less than 0.001), due to the ventilation induced diminution of sodium excretion from the denervated kidney. It is concluded that mechanical ventilation of anesthetized dogs modifies sodium excretion, and this phenomenon can be demonstrated only in the denervated kidney.

Anesthesia

The ontogeny of human thymic epithelium specific antigens as defined by monoclonal antibodies.

The ontogeny of human thymic epithelial antigens was studied by the use of monoclonal antibodies and immunohistological techniques. The results show that the T2/30 antigen, specific for cortical epithelial cells appears later than the BH11, BC3 and AG3 antigens. This is the first demonstration of the developmentally regulated appearance of a thymic epithelium specific antigen (not present in other epithelial cells e.g., skin, mucosa).

Antibodies, Monoclonal

Immature, double negative (CD4-,CD8-) rat thymocytes do not express IL-2 receptors.

IL-2R alpha-chain is expressed on a subset of mouse CD4- and CD8-, double negative (DN) thymocytes. This expression of IL-2R alpha-chain on some DN thymocytes in the mouse has led to the proposal that IL-2 might serve as a principal growth and/or differentiation factor for immature thymocytes. However, previous histologic observations have indicated that IL-2R alpha-chain is not expressed on the subcapsular thymic blasts (an area rich in DN cells) in either huma or rat thymus, whereas all three species display IL-2R expression on a few cells in the thymic medulla. Therefore, we characterized rat DN thymocytes to determine whether they contained an IL-2R+ population. The results show that rat thymic DN cells share several characteristics with mouse DN cells. However, most of the rat strains do not express the IL-2R on DN cells as shown either by immunofluorescence or by IL-2 binding and receptor cross-linking. Thus, the rare medullary IL-2R+ cells were not found in the DN cells. Only in the exceptional F344 rat strain is the IL-2R alpha-chain expressed on a major proportion of thymocytes, including both DN cells and small cortical-type thymocytes. Furthermore, rat DN cells do not contain detectable IL-2 mRNA or cytoplasmic IL-2 activity, thus supporting the conclusion that it is unlikely that IL-2 and IL-2R serve to maintain the proliferation of rat DN thymocytes in vivo. The possible significance of in vivo expression of IL-2R alpha-chain on immature thymocytes in the mouse and in a single rat strain is discussed.

Aging

Detection of IL-1 alpha and IL-1 beta gene expression by in situ hybridization. Tissue localization of IL-1 mRNA in the normal C57BL/6 mouse.

IL-1 is a cytokine with a wide variety of effects on cells involved in inflammatory and immune responses, hemopoiesis, and bone formation. Many cell types have been shown to produce IL-1 in vitro; however, very little is known about the source and role of IL-1 in vivo. By using in situ hybridization, we examined the tissue distribution of cells containing IL-1 mRNA in normal C57BL/6 mice. The results show that many organs contain IL-1 mRNA-positive cells, but the highest frequency was found in lymphoid organs. The distribution and localization of these cells suggest that many of the IL-1 mRNA-producing cells are tissue macrophages. Organs exposed to environmental Ag and microbial products (lymph nodes, liver, intestine, lung, and uterus) had high frequencies of IL-1 mRNA-producing cells, suggesting that IL-1 is produced in local inflammatory or immune responses in vivo. The production of IL-1 mRNA in the thymus and in the bone marrow suggests that IL-1 is available to play physiologic roles in T cell differentiation and in hemopoiesis.

Animals

Renal nerves in exaggerated water and sodium excretion by hypertrophied kidney of anesthetized rats.

The effect of acute renal denervation (RD) on water (V), sodium (UNaV), and potassium excretion (UKV) from the hypertrophied and control kidney was studied in 5-sec-butyl-5-ethyl-2-thiobarbituric acid (Inactin)-anesthetized male rats 7 days after unilateral nephrectomy (Nx) or sham operation (SNx). V, UNaV, and UKV from the hypertrophied kidney were similar before and after RD or sham RD. In contrast, in SNx rats, left RD resulted in an ipsilateral increase in V (from 2.76 +/- 0.39 to 5.31 +/- 0.99 microliters.min-1.g-1), UNaV (from 109 +/- 36 to 857 +/- 331 nmol.min-1.g-1), and UKV (from 144 +/- 44 to 807 +/- 130 nmol.min-1.g-1; P less than 0.05 in all cases). Moreover, renal parameters from the hypertrophied kidney, subjected to either RD or sham RD, were not different from values after RD in SNx rats (V: Nx, sham RD = 5.72 +/- 1.10; Nx, RD = 5.23 +/- 0.66; SNx, RD = 5.31 +/- 0.99 microliters.min-1.g-1; UNaV: Nx, sham RD = 896 +/- 319; Nx, RD = 821 +/- 262; SNx, RD = 857 +/- 331 nmol.min-1.g-1; UKV: Nx, sham RD = 782 +/- 127; Nx, RD = 860 +/- 82; SNx, RD = 807 +/- 130 nmol.min-1.g-1). In additional experiments, integrated renal nerve activity (RNA) to the kidney in Nx and SNx rats was 4.0 +/- 0.3 and 10.7 +/- 0.9 microV (P less than 0.05), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

Formation of lymphoepithelial tissue in the sheep's palatine tonsil.

Formation of lymphoepithelial tissue was studied in 1-, 10- and 21-day-old sheep. From each of the animals one of the tonsils was fixed in 4% glutaraldehyde for light- and electron microscopy while the other was frozen in liquid nitrogen for immunohistochemistry. These examinations revealed sequential histological events during the formation of reticular epithelium. (i) Appearance of a distinct epithelial cell indicates the initiation of the reticulation. The electron density of these epithelial cells is much lower than that of the common keratinocytes but the presence of cytoplasmic tonofibrils and desmosomes provides evidence that they are of epithelial origin. They may represent the precursors of M cells. Their appearance may be followed by expression of Ia+ molecules on the surrounding keratinocytes showed by isolated Ia+ areas in the epithelium. (ii) In the mesenchyme underneath the Ia+ epithelial areas, Ia+ dendritic-like cells emerge which immigrate through the basement membrane into the epithelium establishing a provisional dendro-epithelial tissue. In this stage of the reticular epithelium's formation large Ia+ areas are shown by immunostaining, which include the epithelium and mesenchyme. The origin of the Ia+ dendritic-like cells is uncertain but their distribution and dense accumulation underneath the epithelium suggest that they are transformed tonsillar mesenchymal cells. Similar cell transformation of mesenchymal cells takes place in the bursa of Fabricius prior to development of lymphoepithelial tissue. (iii) The M cell precursors together with the Ia+ dendritic-like cells adapt the epithelium to be suitable for receiving a large number of lymphoid cells. Immigration of the lymphoid cells into the epithelium transforms the dendro-epithelial tissue to a real lymphoepithelial one.

Animals

Structural and histochemical features of cortical thymic epithelial cells in mice with chemically-induced lymphoid leukemia.

Ultrastructural, enzyme histochemical (acide phosphatase, adenosine triphosphatase, neutral 5'-nucleotidase) and immunohistochemical (cytokeratins with monoclonal antibodies BH11 and BC3) features of the thymus cortical epithelial cells of leukemic DBA/2 inbred mice have been studied. In the leukemic mice epithelial cells appeared possessing some ultrastructural and histochemical features of cell activation. Lympho-epithelial complexes, composed mainly of BH11 and BC3 immunoreactive cells and of lymphoid cells were subcapsulary and subseptally found. It is discussed on the eventual involvement of the lympho-epithelial complexes in the intrathymic leukemogenesis during lymphoid leukemia.

Animals

Renal nerves and sodium conservation in conscious rats of different strains kept on various diets.

Earlier contradictory results as to whether renal nerves are necessary for adaptation to a low dietary sodium intake in the rat were ascribed to strain differences or to sympathetic stimulation caused by carbohydrates when changing from a low-sucrose normal-sodium diet to a high-sucrose sodium-deficient diet. In the present work, daily sodium excretion was studied for 4 days before and after bilateral renal denervation or sham operation in three strains of rats (CFY, Wistar, and Long Evans). After ingesting a normal sodium diet containing no sucrose, CFY and Wistar rats were fed a sodium-deficient diet containing 67% sucrose. Long Evans rats were sodium-depleted by feeding them boiled rice. Daily and cumulative sodium excretion and sodium balance were similar in all three groups during 4-day sodium-depletion periods before and after bilateral renal denervation or sham operation. The results suggest that in sodium-depleted rats denervation natriuresis can be ascribed neither to strain differences nor to the high sucrose content of the low-sodium diet.

Animals

No effect of isolation on blood pressure and daily electrolyte excretion in rats.

The effects of isolation stress on mean blood pressure (BP) and on body weight, water and food intake as well as on urine flow, urinary sodium and potassium excretion were studied in CFY and Long Evans rats. During a 7 day isolation period, food and water intake as well as urine flow, urinary sodium and potassium excretion, as expressed for 100 g body weight, were not changed in either group. Body weight increased similarly in isolated (38 +/- 2 g) and aggregated (41 +/- 5 g) CFY rats. Compared to group housed rats, BP in male CFY animals was not increased after a 7 day isolation (111 +/- 3 vs 111 +/- 3 mmHg, NS). In additional experiments high sodium intake by physiological saline drinking slightly elevated blood pressure but failed to induce arterial hypertension in isolated rats (118 +/- 2 vs 121 +/- 3 mmHg, NS). We conclude that, contrary to some reports from other laboratories, isolation stress has no detectable effect on BP and/or water and electrolyte balance.

Animals

Supersensitivity of the renal tubule to catecholamines in the chronically denervated canine kidney.

Experiments were performed on anesthetized dogs to study whether or not renal tubules of the chronically denervated kidney show supersensitivity toward circulating catecholamines. In one kidney the influence of plasma catecholamines was inhibited by intrarenal administration of the alpha adrenergic receptor blocker phenoxybenzamine (POB, 2 micrograms/min), and renal parameters of the infused kidney were compared to those of the contralateral noninfused organ. Before POB infusion urine flow (V), urinary sodium and potassium excretion (UNa V, UKV) as well as clearance of inulin and PAH (GFR, CPAH) were similar in infused and contralateral kidneys in all groups studied. In dogs (n = 8) with two innervated kidneys POB infusion elevated V and UNa V by 53 +/- 13% and 102 +/- 34% (p less than 0.05). In dogs (n = 8) with acute bilateral renal denervation POB administration failed to alter any of the measured parameters. In contrast, V and UNaV from chronically denervated kidneys (n = 7) were increased after POB infusion by 40 +/- 9% and 103 +/- 34% (p less than 0.05). Glomerular filtration rate, CPAH and UKV were not changed by alpha adrenoceptor blockade in any of the groups. In an additional group of animals (n = 8) acute unilateral renal denervation increased V and UNaV to a significantly higher extent (by 282 +/- 85% and 330 +/- 106%) than POB administration did in the innervated kidney and elevated UKV (44 +/- 10%), too.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

Monoclonal antibody-recognizing cone visual pigment.

Monoclonal antibodies were raised to a crude photoreceptor-membrane suspension from chicken retinas. Clones producing antibodies against cone outer segments were selected by screening with immunocytochemistry on semithin sections of the retina. One monoclonal antibody, called COS-1, specifically labelled outer segments of double cones and one type of single cones; outer segments of rods and several single cones were not stained. On immunoblots of retinal photoreceptor membranes, this antibody recognized a protein with an apparent molecular mass of 33,000. The visual pigment character of the 33,000 protein was indirectly established by another monoclonal antibody, OS-2, which labelled all outer segments on semithin sections and four bands (33,000-, 36,000-, 38,000-40,000- and a composite band between 66,000-72,000 MW) on immunoblots. Of these, the 36,000- and the 72,000 MW protein bands were identified with an anti-rhodopsin polyclonal antibody as rhodopsin monomer and dimer. Monoclonal antibody OS-2 is assumed therefore to represent an antibody against a common epitope of all visual pigments of the chicken. The monoclonal antibody COS-1 was found to bind to certain cone outer segments of many other vertebrate species as well.

Animals