Biomedical subjects

A Ríos

Publications and source records attributed to A Ríos.

At least 19 recordsLinked to original sources

PubMed1996

In vitro inhibition of Ca2+/calmodulin-dependent kinase II activity by melatonin.

Recent evidence suggests that a melatonin (MEL) mechanism of action may be through modulation of Ca2+-activated calmodulin (CaM). MEL binds to CaM with a high affinity, and has been shown to act as a CaM antagonist. Among the CaM-dependent enzymes, Ca2+/Calmodulin-dependent protein kinase II (CaM-kinase II) is a particularly abundant enzyme in the nervous system. In the brain it phosphorylates a broad spectrum of substrates, thus modulating important neuronal functions. We describe the MEL effect on CaM-kinase II activity in vitro. CaM-kinase II was purified from rat brain by column chromatography, and identified by Western immunoblotting. CaM-kinase II activity was assessed in the presence of Ca2+/CaM by the kinase's ability to phosphorylate the synthetic substrate syntide-2 and by enzyme autophosphorylation. MEL inhibited CaM-kinase II activity, and enzyme autophosphorylation. Inhibition of the enzyme by 10(-9) M MEL was nearly of 30%. Trifluoperazine (10 microM), W7 (10 microM), and compound 48/80 (30 micrograms/ml), inhibited CaM-kinase II activity by 40%, 42%, and 93%, respectively. Both EGTA (5 mM) and MEL (10(-5) M) abolished autophosphorylation. The effect of MEL on CaM-kinase II activity was specific, since neither serotonin, N-acetylserotonin, nor 6-hydroxymelatonin inhibited its activity. Our results support the hypothesis that MEL acts as a CaM antagonist and cellular functions may be rhythmically regulated by MEL modulation of CaM-dependent protein phosphorylation.

Animals↗

PubMed1996

Serum amino acid changes in rats with thioacetamide-induced liver cirrhosis.

To date, no attempt has been made to study alterations occurring in the amino acid profile in chronic models of thioacetamide-induced liver cirrhosis. In this work, changes in serum amino acids and proteins in rats with thioacetamide-induced liver cirrhosis are reported, together with changes in enzyme activities in the liver and serum. Seventeen female Wistar rats were used. Eight rats were given 300 mg thioacetamide/l in drinking water for 4 months and nine rats were given water ad libitum during the same time-period. Significant increases in glycine, alanine, serine, methionine, glutamate, ornithine, phenylalanine, tyrosine, histidine and proline were observed in rats with the resulting experimental liver cirrhosis. Threonine, taurine, glutamine, lysine and citrulline tended to increase while isoleucine, leucine, aspartate, arginine and tryptophan tended to decrease. Total and nonessential amino acids increased significantly in cirrhotic animals. Total essential and aromatic amino acids tended to increase in the thioacetamide-treated group, whereas branched chain amino acids tended to decrease in the same group. Regarding serum proteins, a decrease in albumin concentration in the thioacetamide-treated animals was the only change detected. The liver enzyme activities under observation (aspartate and alanine aminotransferases, glutamate dehydrogenase and threonine deaminase) were lower in the thioacetamide group. Decreases were significant for both transaminases and threonine deaminase. Results for serum activities showed that transaminases did not change in thioacetamide-treated rats in comparison with controls. In contrast, alkaline phosphatase rose dramatically in cirrhotic rats. We conclude that the serum amino acid pattern in this chronic model of liver cirrhosis resembles in part that of the corresponding human disease.

Administration, Oral↗

PubMed1996

Dietary restriction induces biochemical and morphometric changes in the small intestine of nursing piglets.

The purpose of this study was to evaluate the biochemical and morphometric changes in the small intestine of nursing piglets caused by 60% dietary restriction, and to ascertain whether this model reproduces the intestinal alterations caused by malnutrition in human infants. Piglets subjected to dietary restriction had significantly lower levels of mucosal DNA and protein, and significantly reduced segmental disaccharidase and leucine aminopeptidase activities compared with age-matched, freely fed controls. However, greater disaccharidase-specific activities were observed in duodenum and jejunum of diet restricted piglets compared with controls. Other findings included significantly lower thickness of the mucose, villous height and width, and villous surface area, a significantly lower number of goblet cells, and significantly greater mucosal crypt depth, intraepithelial leucocyte number, and infiltrated cells per area of lamina propria. The model reproduces most of the biochemical and morphometric changes observed in the small intestine of young human infants with chronic diarrhea and malnutrition, and may be useful in further investigations of the biochemical and molecular mechanisms of intestinal alterations caused by primary malnutrition in early infancy.

Animals↗

PubMed1995

Effect of quercitrin on lactose-induced chronic diarrhoea in rats.

Quercitrin (3-rhamnosylquercetin) is a bioflavonoid contained in several crude drugs traditionally used for its antidiarrhoeal activity. The antidiarrhoeic effect of quercitrin on experimental chronic diarrhoea in rats was studied. Adult rats were fed for 14 days with a synthetic diet in which all soluble carbohydrates were substituted by lactose, resulting in chronic diarrhoea with body weight loss, colonic hyperplasia, reduced average cell size, increased alkaline phosphatase activity, increased mucus production and cytopathological alterations of the enterocyte. The rest of the animals were allowed to recover from chronic diarrhoea for 3 or 7 days, by feeding them with a standard diet, and half of them were also given quercitrin orally (50 mg/kg day). Diarrhoea ceased 48 h after lactose withdrawal, and body weight recovery was apparent after 3 days. Nevertheless, most of the alterations of the colonic mucosa persisted at that time. Quercitrin-treated rats had less diarrhoeal output and did not show mucosal hyperplasia after three days of treatment. All animals had greatly recovered by the seventh day, but histological alterations were still present, although to a lesser extent in quercitrin-treated rats. Quercitrin and related flavonoids may play a role in intestinal repair following chronic mucosal injury.

Animals↗

PubMed1995

[Results of a series of 104 consecutive bilateral bone marrow biopsy specimens in lymphoproliferative disorders].

PURPOSE: To establish the incidence of discordance in a series of bilateral bone marrow biopsies (b-BMB) in lymphoproliferative disorders and to determine whether this might lead to changes in the present treatment of each patient. MATERIAL AND METHODS: Between March/1988 and February/1995, 89 patients underwent bilateral bone marrow biopsy (104 b-BMB). Seventy-six underwent one b-BMB; 11 two b-BMB and 2 patients three b-BMB. Sixty-eight b-BMB were done at diagnosis of the disease and 36 for reassessment prior to ABMT. The distribution of the b-BMB by diagnosis was as follows: 54 non-Hodgkin's lymphoma (NHL) -23 low grade NHL and 31 intermediate/high grade NHL-, 44 Hodgkin's disease (HD), 4 multiple myeloma (MM), 1 splenic lymphoma with villous lymphocytes and 1 MM+HD. Specimens were obtained under local anaesthesia with a Jamshidi gauge 8 needle. The biopsies were fixed, decalcified, embedded in paraffin wax and the section cuts were stained (haematoxylin and eosin, Giemsa, Wilder--reticulin--and Masson--collagen--). RESULTS: There was discordance in 5 of the 104 b-BMB (4.8%), but only in four of them was this related to the presence of bone marrow disease, so that incidence falls to 3.8%. Three of them were obtained at diagnosis of the disease (low grade NHL, high grade NHL and HD) and one during reassessment before ABMT. On considering only the specimens that had bone marrow infiltration (19 cases: 14 at diagnosis and 5 in reassessment before ABMT), the absence of concordance in four of them implies that if only unilateral biopsy had been carried out, up to 21% of the cases might have been missed. In one of these patients (HD) this finding led us to replace autologous bone marrow transplantation by autologous peripheral stem cell transplantation. CONCLUSION: On the basis of these data, the use of bilateral bone marrow biopsy specimens may be justified in lymphoproliferative disorders, both at the time of diagnosis and in reassessment prior to ABMT--when the bone marrow was initially infiltrated.

Adult↗

PubMed1993

[DNA identification of human papillomavirus in anogenital condyloma of a male population].

Human Papillomaviruses (HPV) are the cause of benign human anogenital lesions where HPV 6 and HPV 11 are most commonly found. Conversely, HPV 16, 18, 31 and 33 are frequently detected in genital carcinomas and are thus considered as oncogenic types. In order to analyze the prevalence of specific HPV types in an Argentine male population, 43 anogenital lesions from different patients with diagnosis of condyloma acuminata were analyzed. These lesions were localized in different regions of the male genitalia comprising the corona glandis, urethral meatus, skin of the penis, scrotum and anus. The biopsies were screened for the presence of HPV 6, 11, 16, 18, 30, 31 and 33 by Southern blot at different stringent conditions of hybridization (Tm -48 degrees C and Tm -20 degrees C). HPV DNA was found in 41 examined cases (95.3%) with a clear prevalence of HPV 6 and HPV 11 types (51.2% and 23.3% respectively). Six samples (14.0%) were positive only under nonstringent conditions of hybridization. Mixed infections between HPV 16, 18, 30, 31, 33 or a HPV 30 related type with HPV 6 or HPV 11 were detected in 8 specimens (18.6%). Only one case was between HPV 16 and HPV 30. Two additional samples were only positive for HPV 30. Experiments in progress about the prevalence of HPV types in female lesions as well as in normal subjects will contribute to complete the description of the epidemiology of these infections in Argentina.

Adult↗

PubMed1992

Prognostic value of S-phase white blood cell count in B-cell chronic lymphocytic leukemia.

Eighty previously untreated patients with B-cell chronic lymphocytic leukemia (B-CLL) were analyzed to study the proliferation rate of their peripheral blood (PB) leukocytes to determine its relationship with the extension of the disease and its value in discriminating among patients with similar tumor cell mass. The 80 B-CLL patients were distributed into two different groups according to the absolute count of PB S-phase leukocytes: a low proliferative group (less than 1 x 10(9)/I) of 48 patients and a high proliferative group (greater than or equal to 1 x 10(9)/I) of 32 patients. The high proliferative group displayed a higher incidence of splenomegaly (p less than 0.005), hepatomegaly (p less than 0.08), anemia (p less than 0.02) and thrombocytopenia (p less than 0.03) as well as a higher lymphocytic infiltration both in PB (p less than 0.0004) and in bone marrow (BM) (p less than 0.003). These patients also showed a higher incidence of a diffuse pattern of BM involvement (p less than 0.04), advanced clinical stages [stage III/IV (p less than 0.03) and group C (p less than 0.04)] and infections (p less than 0.0008) together with significantly lower IgG (p less than 0.03) and IgM (p less than 0.03) serum levels. Regarding the immunophenotype, there was a greater percentage of either CD19+ (p less than 0.06) and CD19+ CD5+ (p less than 0.05) B-cells, together with a greater reactivity for both the CD25 (p less than 0.04) and CD9 (p less than 0.08) antigens in the high proliferative group. According to the prognostic value of the PB S-phase leukocyte count it was seen that patients with low S-phase white blood cell (WBC) numbers displayed a significantly higher survival (p less than 0.03). In addition, multivariate analysis revealed that the S-phase WBC count, although partially related to other clinical and biological prognostic factors, displayed an important independent value in predicting early deaths in patients with B-CLL.

Aged↗

PubMed1991

Presenting features and prognosis of chronic lymphocytic leukemia in younger adults.

We have analyzed 117 younger patients with chronic lymphocytic leukemia (CLL) (mean age, 44.5 years; SD, 4.8; range, 19 to 49; male/female ratio, 2.08) with three main objectives: (1) to see whether these patients have distinctive presenting clinical features; (2) to investigate the impact of the disease on survival; and (3) to analyze whether already well-known prognostic factors are also useful when applied to these patients. As compared with an older age population (greater than or equal to 50 years), there were no major differences in presenting features except for an increased proportion of males (2.08 v 1.21; P less than .025) and a higher hemoglobin level (13.47 +/- 2.70 g/dL v 12.84 +/- 2.77 g/dL; P less than .05) in the younger group. Median survival is 12.3 years (expected median from a control group, 31.2 years). Clinical stages, bone marrow patterns, blood lymphocyte counts, and its doubling time are all useful to separate different risk groups of patients. Whereas patients with favorable prognostic factors have a survival probability of about 80% 14 years after diagnosis, those with poor prognostic features have a median survival of less than 3 years. It is concluded that CLL in younger adults has no major distinctive presenting features and that known prognostic factors are useful to separate different risk groups of patients. These results should be of help in planning therapy for younger persons with CLL.

Adult↗

PubMed1991

Heterogeneity of T cell lymphoblastic leukaemias.

Twenty eight out of 170 consecutive cases of acute lymphoblastic leukaemia (ALL) were examined. They were of T cell origin, with the following distribution: seven (28%) cases had pre-T or prothymic features; nine (36%) cases showed early thymocytic features, six (24%) had cortical features; and three (12%) had a "mature" phenotype. The remaining three cases could not be sub-classified. A striking finding was that pre-T ALL differed from intrathymic ALL not only in the absence of both E rosettes and intrathymic differentiation antigens, but also in the expression of two non-lineage specific antigens HLA-DR and CD10. Both antigens appear in the bone marrow from the very first stages of lymphoid differentiation, implying that the origin for pre-T ALL is bone marrow. A comparison of the clinical features of pre-T and thymic ALL showed that pre-T ALL disease showed a pattern more similar to non-T ALL disease: a lower incidence of mediastinal mass, absence of extrahaematopoietic disease, lower white cell counts and haemoglobin concentrations, and a higher incidence of bone pain. No obvious difference in response to treatment was apparent. The results show that T-ALL is not only a heterogeneous immunological group but also suggest that it may have different origins: bone marrow for pre-T ALL and the thymus for thymic ALL.

Adolescent↗

PubMed1991

Haemopoietic phagocytes in the early differentiating avian retina.

The existence of specialised phagocytic cells is described in regions of the retinal neuroepithelium undergoing intense cell death during early differentiation of the avian embryo retina (2.5-5 days of incubation). These results were obtained using routine techniques for light microscopy, acid phosphatase histochemistry and immunocytochemical staining with antibodies MB-1 and QH-1, both specific for quail endothelial cells and all blood cells except mature erythrocytes. Specialised phagocytes were distinguishable from neuroepithelial cells on the basis of morphological criteria: in the former, the nucleus was not oval in shape and was not oriented perpendicular to basement membrane neuroepithelium. The cytoplasm of the specialised phagocytes was often filled with dead cell fragments. In contrast to neuroepithelial cells, the specialised phagocytes showed acid phosphatase activity and were labelled with both MB-1 and QH-1 antibodies in normal quail embryos and chick----quail yolk sac chimeras. Moreover, some acid phosphatase positive and MB-1/QH-1 positive cells also appeared in the presumptive vitreous body, at the edges of the optic cup and in the surrounding mesenchyme. As the vitreal cells and the specialised phagocytes of the neural retina were immunolabelled in chick----quail yolk sac chimeras, we conclude that they are derived from haemopoietic cells in the yolk sac. Some images suggest that these cells enter the vitreous body from the surrounding mesenchyme and traverse the basement membrane of the neuroepithelium in the optic disc region to give rise to the specialised phagocytes of the retinal neuroepithelium.

Acid Phosphatase↗

PubMed1990

Use of photochemical reactions in flow injection: determination of oxalate in urine.

The use of photochemical reactions in flow injection (FI) is reported. The irradiation of an FI reactor with a suitable source facilitates the development of the iron(III)-oxalate reaction, allowing the amperometric determination of the anion in the range 1.0-13.0 micrograms ml-1, with a relative standard deviation of 1.1% and a sampling frequency of 40 h-1. The proposed method was applied successfully to the determination of oxalate in urine samples.

Humans↗

PubMed1990

Bone marrow biopsy in myelodysplastic syndromes: morphological characteristics and contribution to the study of prognostic factors.

Ten characteristics of bone marrow (BM) biopsies in paraffin sections, obtained at diagnosis from patients with myelodysplastic syndromes (MDS) classified according to the FAB criteria, were analysed to identify both the most relevant morphologic data and any possible influence on survival. Agreement between two observers was obtained for 94% of the data. BM cellularity was increased in 63% of the cases and was higher in refractory anaemia with excess of blasts (RAEB). RAEB in transformation (RAEB-t) and chronic myelomonocytic leukaemia (CMML) (P = 0.001). Dysmegakaryopoiesis and dyserythropoiesis were present respectively in 83% and 72% of the cases, with slight differences among the FAB subtypes. Abnormal localization of immature precursors (ALIP) was found in more than half of the cases and somewhat more frequently seen in the RAEB + RAEB-t + CMML group (P = 0.07). Eosinophilia, plasmacytosis and reticulin fibrosis were evident in 26%, 18% and 47% of the cases respectively. Cellularity (P = 0.006), eosinophilia (P = 0.009) and, to some extent, dysmegakaryopoiesis (P = 0.07) bore a certain relationship with survival on univariate analysis. The presence of ALIP was not seen to affect the outcome. Multivariate analysis showed that the cellularity and presence of dysmegakaryopoiesis, in BM biopsy, added significant independent prognostic information to that achieved with age, platelet count and proportion of blast cells in BM aspirate, three variables with proven prognostic value in MDS patients. Using a regression model including these five characteristics we have stratified the patients into low, intermediate and high-risk groups with different survivals (P = 0.00001). The present findings show that BM biopsy is able to provide both morphological characteristics and information about the prognosis of survival, and should thus be included in the initial evaluation of MDS.

Adult↗

PubMed1989