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M Riera

Publications and source records attributed to M Riera.

69 records · Page 4Linked to original sources
PubMed1991

Role of erythrocyte organic phosphates in blood oxygen transport in anemic quail.

The effects of two different degrees of experimentally induced anemia and the consequent high percentage of circulating immature erythrocytes on oxygen affinity (pH 7.5 and 41 degrees C), erythrocyte organic phosphates, and Hb fractions have been studied in quail. Blood reticulocytes reached percentages of 24 and 69-87% in the first and second experiments, respectively. Variations in the phosphate levels found during the anemic process were related to the amount of circulating reticulocytes. The erythrocyte [ATP] (brackets indicate concentration) and [ATP]/[Hb] molar ratio increased with the release of reticulocytes and returned to control levels as they matured. The erythrocyte [inositol pentakisphosphate (InsP5)] decreased significantly when circulating reticulocytes showed their highest values, whereas there was hardly any effect on the [InsP5]/[Hb] molar ratio, which changed only slightly. Hb-O2 affinity also exhibited no statistical changes associated with acute anemia. These latter findings indicate that InsP5, at physiological concentrations, is the primary modulator of quail Hb function; the observed rise in [ATP] has no additional influence on Hb-O2 affinity. It is suggested that InsP5 tends to maintain the blood oxygen affinity in both mature erythrocytes and reticulocytes. The main compensatory response at blood level is a rapid bulk reticulocyte release from medulla.

Adenosine Triphosphate↗
PubMed1991

Visceral leishmaniasis: another HIV-associated opportunistic infection? Report of eight cases and review of the literature.

Visceral leishmaniasis (VL) is considered an opportunistic infection in immunocompromised patients. We review the clinical, laboratory, and therapeutic data in 63 patients (eight new cases and 55 cases reported in the literature) with Mediterranean VL (kala azar) and HIV-1 infection to determine whether VL should be considered an opportunistic infection in HIV-infected adults. We conclude that: (1) in areas where both leishmaniasis and HIV-1 infection are endemic, VL may be more frequent among HIV-infected adults; (2) in HIV-infected patients, the clinical picture did not differ significantly from classical kala azar, although it often ran a recurrent course, with resistance to antimonial therapy. We propose the inclusion of VL in the IVC-2 subgroup of the Centers for Disease Control (CDC) clinical classification of HIV-1 infection while prospective and larger studies further define whether there are clinical presentations that could justify adding VL to the list of opportunistic infections indicative of AIDS.

Adolescent↗
PubMed1990

Changes in haemoglobin oxygen affinity and erythrocytic 2,3-BPG in ethanol-treated rats.

1. The effects of alcohol on blood oxygen transport properties were studied in rats after a chronic administration of ethanol in drinking water. 2. Ingestion of ethanol provokes an increase in haemoglobin oxygen affinity (at pH 7.4). This is caused by a drop in the MCHC and erythrocyte 2,3-BPG concentration that give rise to a decrease in the 2,3-BPG/Hb ratio. 3. No changes in haemoglobin fractions were observed. 4. The results indicate a depletion in the red blood cell glycolytic pathways. 5. If metabolic acidosis occurs, the expected loss of blood affinity in vivo due to the fall in pH would be compensated by the changes observed in vitro.

2,3-Diphosphoglycerate↗
PubMed1989

[Cerebral toxoplasmosis in patients with AIDS].

A retrospective study was made of the cases of cerebral toxoplasmosis (CT) diagnosed since 1985 in patients with AIDS. In the period studied, out of a total of 70 patients with AIDS, 13 (18.5%) were diagnosed with CT. In eight cases (11%) CT was the first illness indicating AIDS. The clinical, neuro-radiological and serological findings were analyzed. Also the response to treatment with pyrimethamine and sulfadiazine. Although the rate of mortality from CT has been very low among our patients, relapses have been frequent, even in patients who were on maintenance treatment with pyrimethamine, and in the medium term the prognosis is made more gloomy by the appearance of other opportunistic infections.

Acquired Immunodeficiency Syndrome↗
PubMed1987

On the preservation of avian blood cells.

The functional state of erythrocytes from hen during their conservation with a preserving solution for 24 days at 4 degrees C, has been estimated by studying some biochemical and hemorheological parameters. Results show an initial phase in the preservation period (4-5 days) in which red blood cells maintain their values at levels similar to those at the beginning of the experience, except for osmotic resistance. Furthermore a progressive erythrocyte deformability loss, linked to ATP depletion (with rise in inorganic phosphate levels) as well as a gradually higher rate of hemolysis, were detected.

Adenosine Triphosphate↗
PubMed1983

Erythrocytic phosphates and flying activity in birds.

1. The intraerythrocitary organic phosphates in different avian species (Sturnus vulgaris, Apus apus, Gallus gallus domesticus, Coturnix coturnix japonica and Columba livia) were analyzed by ionic exchange chromatography. The chromatograms of these species revealed the presence of ADP, ATP, GTP, IPP and inorganic phosphate. 2. The main organic phosphates (ATP and IPP) and the inorganic phosphate were also evaluated, directly, in other specimens. The IPP levels were very similar in all species; however, for ATP, there were great differences, with the lowest value in chickens (1.53 mumol/ml) and the highest value in starlings (5.58 mumol/ml). 3. A progressive training program for homing pigeons with flights from 80 to 760 km did not cause significant variations in IPP levels. Nevertheless, the ATP concentration values showed significant changes. 4. A specific relationship between the flying habits in different species of birds or the training exercise for pigeons and the erythrocyte organic phosphates, was not evident. 5. Hematocrit and hemoglobin values showed significant changes during the progressive training program.

Animals↗
PubMedDate not supplied

Effect of human natural xenoantibody depletion and complement inactivation on early pig kidney function.

Preformed xenoreactive natural antibodies (XNA) and complement mediate hyperacute xenograft rejection (HXR) in pig-to-human discordant xenotransplantation. In a pig kidney-human blood xenoperfusion model, we investigated whether XNA depletion and/or human complement inactivation preserved early pig kidney function. Pig kidneys were perfused for 180 min with pig blood (AUTO group, n = 8), human blood (HETER group, n = 6), complement-inactivated human blood (COMi group, n = 5), XNA-depleted human blood (ABd group, n = 5) or complement-inactivated and XNA-depleted human blood (ABd&COMi group, n = 5). HETER kidneys were rejected after 15-30 min and showed vascular microthrombi and interstitial hemorrhages. XNA depletion and/or complement inactivation prevented HXR. The glomerular filtration rate in ABd, COMi and ABd&COMi groups was significantly lower than in the AUTO group. Also, beyond 60 min, the COMi group showed a significantly lower glomerular filtration rate than that observed in ABd and ABd&COMi groups. Kidneys from ABd, COMi and ABd&COMi groups displayed endothelial cell edema, as well as higher soluble P-selectin levels and a higher renal myeloperoxidase content than the AUTO group kidneys. COMi and ABd&COMi groups had a significantly lower renal myeloperoxidase level than the HETER group. Also, in contrast to HETER and ABd groups, these complement-inactivated groups failed to show a positive correlation between P-selectin and renal myeloperoxidase. We also investigated platelet-activating factor (PAF) as possible mediator for these functional and pathologic changes. We found that blood PAF levels were similar in HETER, ABd, COMi and ABd&COMi groups and significantly higher than in the AUTO group. Also, when PAF was added to porcine endothelial cell monolayers, morphological changes due to cytoskeleton contraction were observed, and these changes were prevented by preincubation with a PAF receptor antagonist. In conclusion, although depletion of XNA and/or complement inactivation prevent HXR, the pig kidney function is not preserved at the level of the autologous combination. The PAF overproduction observed in the xenogenic combination, which is independent of the presence of XNA and complement, may be, at least in part, responsible for early endothelial cell morphological changes still present when HXR is prevented.

Animals↗
PubMedDate not supplied

[Campylobacter gastroenteritis in patients with human immunodeficiency virus infection].

BACKGROUND: Campylobacter bacteria are frequent, and usually slight causes of diarrhea in a normal host while in an immunosuppressed host the diarrhea may lead to severe pictures. The aim of this study was to analyze the clinical features of gastroenteritis by Campylobacter spp. in hospitalized seronegative patients and in those with HIV infection. METHODS: A retrospective study of the cases of gastroenteritis by Campylobacter spp. in adult patients admitted in the authors' hospital from January 1988 to July 1993 was carried out. RESULTS: Of the 20 patients studied with gastroenteritis by Campylobacter spp., 13 (65%) had HIV infection. The mean age of the patients was 38 years (range: 18-68 years) with 70% of the cases being males. Seventy seven percent of the HIV positive patients showed diagnostic criteria for AIDS while 71% of the seronegative patients showed a base disease and/or received steroid therapy. The length of the diarrhea was greater in the patients with HIV infection on comparison with the seronegative patients (25 vs. 6 days). The diarrhea persisted for more than 2 weeks in more than half of the cases of seropositive patients. Fever continued a mean of 24 days in the HIV positive patients as compared with only 5 days in the HIV negative cases. Most of the former patients were treated with erythromycin with good response. Gastroenteritis recurred in one patient and another patient with HIV infection presented a pseudoappendicular picture. No case of bacteremia was detected in either the seropositive or seronegative patients. Campylobacter jejuni was isolated in most of the cases with a high percentage of resistence to quinolone drugs. The mean CD4 lymphocyte count in HIV positive patients was 131/mm3 (range: 1-774). Mean survival following diagnosis of gastroenteritis by Campylobacter spp. was 8.9 months (range: 1-17) in the patients with AIDS. CONCLUSIONS: Gastroenteritis by Campylobacter spp. in hospitalized patients was related with immunosuppressive states. A clinical profile of prolonged febrile diarrhea was common in HIV positive patients and was associated with a low number of CD4 lymphocytes, advanced HIV infection and short survival.

Acquired Immunodeficiency Syndrome↗