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Biomedical subjects

P Ramos

Publications and source records attributed to P Ramos.

At least 55 records · Page 3Linked to original sources
PubMed1996

Testicular cell cytoskeleton in the newt, Triturus marmoratus marmoratus, during the annual cycle.

Light and electron microscopy immunohistochemical studies and Western blotting analysis of cytoskeletal proteins have been carried out in the testis of the marbled newt (Triturus marmoratus marmoratus) during the annual testicular cycle. The present findings revealed homologies and differences with regard to those reported in the testes of mammals and other vertebrates. Changes in immunohistochemical expression have also been detected in the course of the annual cycle. Actin and tubulin, which were scanty and diffusely located in spermatogonia and spermatocytes, increased their expression and reorganized during spermiogenesis. Vimentin and keratin, undetected in spermatogonia and spermatocytes, were expressed in differentiating spermatids and spermatozoa. In these cells, actin might be related with the connection of the axial fiber to the undulating membrane and the coordination of movement by both structures, while vimentin might be involved in the maintenance of the spatial relationship between the axoneme and the marginal fiber. During the first stages of spermatogenesis, the cytoplasm of Sertoli cells (follicular cells) showed a diffuse immunoreaction to actin, myosin, and tubulin and no vimentin immunolabeling. In advanced spermiogenesis, the follicular cells showed an intense immunoreaction to actin, myosin, tubulin, and vimentin in the apical projections that surrounded the spermatid heads. These apical cytoskeletal components might be involved in spermatid elongation, since the spermatids display no manchette, and in spermatozoon positioning and grouping. The colocalization of myosin and actin in the follicular cells suggests that actin filaments from contractile bundles and that contraction might be involved in changes in the Sertoli cell shape that accompany germ cell development during spermatogenesis. The interstitial cells immunostained to actin, myosin, tubulin, and vimentin. These cells, together with follicular cells, seemed to form the glandular tissue cells which showed a similar immunophenotype. The cells that surrounded the efferent duct epithelium immunostained to desmin, and they are probably contractile cells involved in sperm evacuation.

Activity Cycles↗
PubMed1996

Preparation of fatty acid methyl esters from lipoprotein and macrophage lipid subclasses on thin-layer plates.

A simple, accurate, and fast procedure for quantitative analysis of fatty acids (FA) in simple lipid subclasses from different biological specimens is presented. Lipid extracts of isolated plasma lipoproteins (very low, low, and high density lipoproteins; VLDL, LDL, and HDL, respectively) and permanent J774 mouse macrophages were fractionated into lipid subclasses by thin-layer chromatography (TLC) on silica gel 60 plates. Bands comigrating with authentic lipid standards were scraped off under argon and subjected to direct, in situ transesterification with BF3/MeOH in the presence of the TLC adsorbent. Fatty acid methyl esters were subsequently quantitated by capillary gas chromatography. A comparison of the FA content present in total lipid extracts and in lipid subclasses separated by TLC revealed recoveries ranging from 93 (J774 cell extracts) to 99.7% (LDL). The method described is applicable for the measurement of FA in individual lipid subclasses and was successfully applied to quantitatively analyze the FA composition of the phospholipid, triacylglycerol, and cholesteryl ester fraction derived from VLDL, LDL, and HDL. In J774 lipid extracts, the FA composition of the phospholipid-, monoacylglycerol-, diacylglycerol-, free fatty acid-, triacylglycerol-, and cholesteryl ester fraction was quantitated. In addition we have analyzed the time-dependent loss of the major HDL polyunsaturated fatty acids (18:2, 20:4) in the phospholipid and cholesteryl ester fraction during copper-dependent peroxidation of HDL. We have not encountered analytical problems concerning low FA recoveries from CE-rich lipid extracts as indicated by almost quantitative recoveries of FA in LDL, HDL, and J774 extracts.

Animals↗
PubMed1996

Factors affecting resistance of low density lipoproteins to oxidation.

Oxidation resistance (OR) of low density lipoproteins (LDL) is frequently determined by the conjugated diene (CD) assay, in which isolated LDL is exposed to CU2+ as prooxidant in the range of 1-10 microM. A brief review on major findings obtained with this assay will be given. A consistent observation is that vitamin E supplements or oleic acid-rich diets increase OR. Oxidation indices measured by the CD assay and effects of antioxidants very significantly depended on the Cu2+ concentration used for LDL oxidation. For medium and high Cu2+ concentrations, the relationship between lag time and propagation rate can be described by a simple hyperbolic saturation function, which has the same mathematical form as the Michaelis-Menten equation. At medium and high Cu2+ concentrations (0.5 to 5 microM), vitamin E increases lag time in a dose-dependent manner. The increase is higher for 0.5 microM Cu2+ as compared to 5 microM. At low Cu2+ concentrations (0.5 microM or less), the mechanism of LDL oxidation changes. Significant oxidation occurs in a preoxidation phase, which commences shortly after addition of Cu2+. Preoxidation is not inhibited by vitamin E. It is concluded that much additional work is needed to validate the importance of oxidation indices derived from CD and similar assays.

Antioxidants↗
PubMed1996

The EXT2 multiple exostoses gene defines a family of putative tumour suppressor genes.

Hereditary multiple exostoses (EXT) is an autosomal dominant condition characterized by short stature and the development of bony protuberances at the ends of all the long bones. Three genetic locl have been identified by genetic linkage analysis at chromosomes 8q24.1, 11p11-13 and 19p. The EXT1 gene on chromosome 8 was recently identified and characterized. Here, we report the isolation and characterization of the EXT2 gene. This gene shows striking sequence similarity to the EXT1 gene, and we have identified a four base deletion segregating with the phenotype. Both EXT1 and EXT2 show significant homology with one additional expressed sequence tag, defining a new multigene family of proteins with potential tumour suppressor activity.

Amino Acid Sequence↗
PubMed1996

IL-2 effects on allogeneic and autologous transplant haemopoietic progenitors in long-term cultures.

IL-2 therapy may be useful in situations with a low tumour burden, such as after autologous transplantation. However, conflicting reports about the deleterious effects of this cytokine on haemopoiesis have precluded its widespread use. To study IL-2 effects on haemopoietic transplant progenitors we established long-term cultures (Dexter-type) with cells from allogeneic marrow and marrow/peripheral blood cell infusates of autologous transplants with different concentrations of IL-2 (0-1000 IU/ml). Percentage of CD56+ cells was also determined in cultures. IL-2 induced an inhibitory effect on stroma and an increase in the percentage of CD56+ cells compared with controls. No deleterious effect either in the production of BFU-E or CFU-GM weekly or over the whole period of culture was observed. Our results suggest that IL-2 is able to induce an increase in CD56+ cells early after transplantation without a deleterious effect on long-term haemopoiesis.

Bone Marrow↗
PubMed1996

[Renin plasma profile and sodium sensitivity of blood pressure in hypertensive patients with or without a family history of hypertension].

The relationship between sodium-sensitive hypertension, renin profile and genetic predisposition to hypertension have not been fully clarified. The present study aimed to establish the influence of family history of hypertension (at least one of the parents suffering from hypertension) on the renin profile, incidence of sodium-sensitivity of blood pressure and plasma concentration of selected biochemical parameters (creatinine, uric acid, glucose, sodium, potassium, calcium and cholesterol). 85 patients with essential hypertension (38 females, 47 males) were enrolled in the study. Secondary forms of hypertension were excluded in all patients by careful clinical and biochemical examination performed in the Department of Nephrology, Silesian University School of Medicine in Katowice. Plasma renin activity (PRA) was estimated twice: first after administration of a normal sodium diet (100-120 mmol of sodium per day) and 8 hours of supine position (PRA I) and a second time after 3 days of sodium restriction (10-20 mmol of sodium per day) and 3 hours of upright position (PRA II). All other biochemical parameters were measured once. Only patients with urinary sodium excretion lower than 60 mmol per day (after 3 days of low salt diet), were enrolled in the study. Sodium-sensitive hypertension was diagnosed in patients with a decrease of mean arterial blood pressure (MAP) of more or equal to 10 mm Hg after three days of sodium restriction. Reduction of MAP of less than 10 mm Hg was classified as sodium-nonsensitive hypertension. Among 85 patients with essential hypertension 49 (57.6%) had a positive (group I) while 36 (42.4%) a negative family history of hypertension (group II). Using the criteria presented in this study low, normal, high and rigid plasma renin activity were found, in 14.3%, 57.1%, 18.4% and 10.2% respectively of patients of group I. In patients of group II the incidence of the above mentioned renin profiles was similar: 13.9%, 58.3%, 19.4% and 8.4% respectively. In patients of group I 16 (32.7%) had sodium-sensitive and 33 (67.3%) sodium-nonsensitive hypertension, while in patients of group II 16 (44.4%) had sodium-sensitive and 20 (55.6%) sodium-nonsensitive hypertension (difference between group I and group II is statistically not significant). Patients of group I did not differ significantly from patients of group II with respect to : sex, age, blood pressure, sodium urinary excretion and plasma concentration of above mentioned parameters. From results obtained in this study we may conclude, that patients with and without history of essential hypertension do not differ with respect to renin plasma profile, incidence of sodium-sensitivity of blood pressure and other biochemical parameters.

Adult↗
PubMed1996

Comparative responsiveness to prolonged hyperinsulinemia between adipose-tissue and mammary-gland lipoprotein lipase activities in pregnant rats.

The present study was addressed to determining the comparative responsiveness of lipoprotein lipase (LPL) activity, in white adipose tissue and mammary gland, to a prolonged hyperinsulinemic stimulus, in pregnant and virgin rats. Pregnant rats at the 17th day of gestation and virgin animals were subjected, under conscious and unrestrained conditions, to a continuous infusion with either 50% glucose or double-distilled water (controls) (35 ml/day) for 72 h through a catheter in the jugular vein. The basal plasma-glucose levels were lower in pregnant than in virgin rats. After the glucose infusion plasma-glucose levels remained unchanged but plasma-insulin levels were much higher, and this effect was greater in pregnant than in virgin rats. Whereas LPL activity in white adipose tissue in the controls was lower in pregnant than in virgin rats, in rats receiving the glucose infusion it increased more in pregnant than in virgin rats. However, LPL activity in the mammary gland was already higher in control pregnant rats than in virgin controls and the glucose infusion caused a similar increase in both groups. Although there was a linear correlation when individual values, from all the studied rats, for LPL activity in both tissues were plotted against plasma insulin levels, the correlation coefficient was much higher for mammary-gland LPL activity than for adipose-tissue LPL activity. Plasma-triglyceride levels were higher in pregnant than in virgin rats. The glucose infusion did not modify this parameter, probably because of the changes in LPL activity in other tissues which are known to occur in the opposite direction to those observed in this study for adipose tissue and mammary gland. The present results support the notion that the insulin resistant condition which normally occurs during late gestation is responsible for the decreased LPL activity in adipose tissue, but that the mammary gland remains sensitive to insulin and so maternal hyperinsulinemia would contribute to the induction of LPL activity in this organ prior to parturition.

Adipose Tissue↗
PubMed1995

Massive upregulation of the Fas ligand in lpr and gld mice: implications for Fas regulation and the graft-versus-host disease-like wasting syndrome.

Fas-deficient lpr and gld mice develop lymphadenopathy due to the accumulation of T cells with an unusual double negative (DN) (CD4-CD8-) phenotype. Previous studies have shown that these abnormal cells are capable of inducing redirected lysis of certain Fc receptor-positive target cells. Since the Fas ligand (FasL) has recently been shown to be partly responsible for T cell-mediated cytotoxicity, lymph node cells from lpr and gld mice were examined for the expression of FasL mRNA. Northern blot analysis revealed that lymph node cells obtained from lpr and gld mice had a striking increase in the level of expression of FasL mRNA predominantly due to expression in the DN T cells. Furthermore, lpr, but not gld lymph node cells killed the B cell line, A20, in a Fas-dependent manner. These findings indicate that Fas mutations result in a massive up-regulation of FasL which, most likely, results from repetitive exposure to (self) antigen. This phenomenon could explain the lpr-induced wasting syndrome observed when lpr bone marrow-derived cells are adoptively transferred to wild-type recipients.

Age Factors↗
PubMed1995

Reversion of insulin resistance in the rat during late pregnancy by 72-h glucose infusion.

To determine whether sustained exaggerated hyperinsulinemia in normoglycemic rats modifies insulin responsiveness during pregnancy, 17-day-pregnant and virgin rats were studied after receiving a continuous intravenous infusion (35 ml/day) of either 50% glucose or bidistilled water (controls) for 72 h. Plasma glucose was unchanged, whereas insulin was highly increased, and the effect was more marked in pregnant than in virgin rats. Insulin responsiveness, estimated under the hyperinsulinemic euglycemic clamp with 0.8 IU insulin.h-1.kg-1, was lower in control pregnant than in virgin rats but higher in pregnant than in virgin rats in those that had received the glucose infusion. The tissue glucose utilization metabolic index (GUI) was estimated with 2-deoxy-D-[1-3H]glucose in the clamped rats. The GUI was lower in heart, white- and red-fiber skeletal muscle, and adipose tissue in control pregnant rats than in control virgin rats, and, although the glucose infusion decreased that index in both red-fiber muscle and adipose tissue in virgin rats, glucose increased the index in red-fiber muscle in pregnant rats to the level found in virgin controls. Results therefore show that, when unaccompanied by hypoglycemia, sustained exaggerated hyperinsulinemia decreases insulin responsiveness in virgin rats but reverts insulin resistance in late-pregnant rats.

Animals↗
PubMed1995

Effect of temperature and phase transition on oxidation resistance of low density lipoprotein.

The study of the effect of temperature on the kinetics of low density lipoprotein (LDL) oxidation was carried out by measuring the conjugated diene (CD) versus time curves at a fixed LDL concentration (0.1 microM) and at different Cu2+ concentrations (0.5-10 microM) in a wide temperature range, from 10 degrees C to 45 degrees C. The core melting point of the LDL determined with differential scanning calorimetry was 31.1 degrees C. We have demonstrated that temperature exerts a clear effect in the Cu(2+)-mediated LDL oxidation, with a strong decrease in lag time and a notable increase in the rate of propagation. This temperature dependence of lag time and rate of propagation fully obeys the Arrhenius law, suggesting that the core melting point of the LDL has no or only a minor effect on these oxidation indices. The Arrhenius plots of the binding of Cu2+ to LDL, measured by K, gave two breaks suggesting that this value is affected by the core transition of the LDL as well as by structural changes at around 15 degrees C. The mean activation energy during rate of initiation was 13.5 kcal/mol and tended to decrease with increasing Cu2+ concentration. The activation energy in the propagation phase was 10.6 kcal/mol and was independent of Cu2+ concentration. In this work we have also shown that the CD method can be conducted with high reproducibility and that a sucrose-supplemented plasma frozen at -80 degrees C can be used as a source of LDL with an unvarying vitamin E content and reproducible oxidation properties.

Blood Preservation↗
PubMed1995

[Etiology and outcome of acute renal failure in elderly patients].

Etiology, clinical course and prognosis were analysed in 346 patients with anuric/oliguric acute renal failure (ARF) treated in the Department of Nephrology, Silesian University School of Medicine in Katowice from January 1984 to December 1993. 41 of them were over 65 years of age (mean age 70.9 +/- 0.7 years) while 305 were younger (mean age 40.6 +/- 0.7 years). According to etiology patients with ARF of both groups were allocated into following subgroups: medical, urological, obstetric, rhabdomyolysis, toxic, traumatic and surgery. Total mortality was similar in both groups of patients (34.0% in older and 40.6% in younger patients respectively). Mean hospitalization time was also similar in both groups of patients with ARF (23.8 +/- 2.3 and 22.0 +/- 0.8 days respectively). Medical, urological and surgical factors were the most frequent causes of ARF in the elderly while traumatic causes and intoxications were extremely rare in these patients. Mortality in the individual etiological groups of ARF was of similarly magnitude in both examined groups. These results suggest that older age does not significantly worsen the outcome of ARF.

Acute Kidney Injury↗
PubMed1994

Transplacental exposure to genotoxins. Evaluation in haemoglobin of hydroxyethylvaline adduct levels in smoking and non-smoking mothers and their newborns.

The N-(2-hydroxyethyl)valine (HOEtVal) adduct resulting from the interaction of ethylene oxide with the N-terminal valine in haemoglobin, was determined in blood samples taken from non-smoking pregnant women (n = 10) and from pregnant women (n = 13) smoking 15 or more cigarettes a day. The HOEtVal levels were also determined in the haemoglobin from blood samples taken, within 48 h of delivery, from the newborns of these mothers. In the maternal haemoglobins, the average HOEtVal adduct level was increased from a background of 63 +/- 20 (mean +/- SD) pmol/g globin in the non-smoking mothers to 361 +/- 107 (mean +/- SD) pmol/g globin in the smoking mothers. Haemoglobin adducts were also detected in all the babies' blood samples. The concentrations in the newborns from smoking mothers [147 +/- 68 (mean +/- SD) pmol/g globin] was significantly higher (P < 0.01) than the concentrations in the newborns from non-smoking mothers [42 +/- 18 (mean +/- SD) pmol/g globin]. A significant correlation (P < 0.01) was found between newborns and maternal HOEtVal adduct levels.

Carcinogens↗
PubMed1994

The apoptosis-1/Fas protein in human systemic lupus erythematosus.

Three independent mutations involving the apoptosis-1 (APO-1)/Fas receptor or its putative ligand have led to lupuslike diseases associated with lymphadenopathy in different strains of mice. To determine whether humans with SLE also have a defect in this apotosis pathway, we analyzed the expression of APO-1 on freshly isolated blood mononuclear cells and on lymphocytes activated in vitro using flow cytometry and the monoclonal antibody anti-APO-1. Significantly higher level of APO-1 expression were detected on freshly isolated peripheral B cells and both CD4+ and CD8+ T lymphocyte populations obtained from lupus patients when compared with normal controls (P < 0.001). Almost 90% of the cells that stained positive for APO-1 also expressed the CD29 antigen, suggesting that APO-1 was upregulated after lymphocyte activation in vivo. No defect in APO-1 regulation was detected after activation of SLE T (with anti-CD3) or B (with Staphylococcus aureus Cowan 1) lymphocytes in the presence of IL-2 in vitro. Similarly, the anti-APO-1 antibody induced apoptosis in 74 +/- 5% of activated SLE T cells in vitro compared with 79 +/- 6% of the normal controls (P > 0.05). These results reveal that, while APO-1/Fas may play an important role in the regulation of lymphocyte survival in SLE, no consistent defect in the expression or function of the receptor could be detected in these studies.

Antigens, Surface↗