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Biomedical subjects

M Riera

Publications and source records attributed to M Riera.

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

Rat liver pp49, a protein that forms complexes with protein kinase CK2, is composed of the beta and the gamma subunits of translation initiation factor eIF-2.

Comparison of the amino acid sequences of two peptides derived from proteolysis of rat liver pp49 identified it as composed of the beta-subunit and the gamma-subunit of eukaryotic initiation factor-2 (eIF-2). Partial purification of rat liver eIF-2 showed that its trimeric form (alpha beta gamma) co-eluted with protein kinase CK2. Heat-inactivated preparations of the trimeric form of eIF-2 inhibited CK2, increasing its Km for beta-casein, as observed with pp49. The form of eIF-2 that lacks the beta-subunit had no effect on CK2. These data indicate that the beta gamma subunits of eIF-2 may complex with CK2 and modulate its activity.

Amino Acid Sequence↗
PubMed1996

Changes in renal hemodynamics and physiology after normothermic ischemia in animals supplemented with eicosapentaenoic acid.

In order to determine whether treatment of animals with an n-3 fatty acid, eicosapentaenoic acid (EPA), could modify renal hemodynamics and physiology after normothermic ischemia, we studied 42 Spraque Dawley rats orally supplemented with either olive oil or a purified lysine salt of EPA for 4 weeks. Four experimental groups were established. Three groups were treated with increasing doses of EPA: 20 mg/kg per day (EPA 20), 40 mg/kg per day (EPA 40) and 80 mg/kg per day (EPA 80), and one group was supplemented with isovolumetric olive oil (OLI). A control group that received neither EPA nor ischemia was also studied. On day 28, right nephrectomy was performed, followed by 30 min of left renal warm ischemia. Basal arterial pressure and renal blood flow (RBF) were monitored in two kidneys before arterial occlusion and continuously thereafter throughout the experiment in one kidney using an electronic transducer and a flowmeter. From 60 to 120 min after the end of ischemia, urine output (microliter/min), glomerular filtration rate (GFR, microliter/min), measured by inulin clearance, and fractional reabsortion of sodium (FRNa) were determined every 20 min. Renal plasma flow (RPF, ml/min) and renal vascular resistance (VR, mm Hg/ml per min) were calculated. RPF was estimated as RBF (1-hematocrit). Before ischemia, the mean RPF and RBF were higher in EPA-fed than in olive oil-fed animals and after ischemia showed a significantly greater increase in EPA-fed animals than in olive oil-fed animals. Mean VR was lower in EPA-fed animals than in olive oil-fed animals, both before arterial occlusion and after ischemia. Mean urine output was similar in the OLI and EPA 20 groups, and significantly higher in the EPA 40 and EPA 80 groups than in the control group. GFR was significantly lower in the OLI and EPA 20 groups than in the control group. Finally, the EPA 40 group showed a similar and the EPA 80 group a slightly higher GFR than the control group. We conclude that EPA supplementation provides protection from renal ischemic-reperfusion injury, and this effect is more evident at higher EPA doses.

Animals↗
PubMed1996

Effects of air pollution on hematological parameters in passerine birds.

The effects of atmospheric air pollution on some hematological, and bioquimic parameters, of passerine birds were analyzed. The studies were undertaken in the area of Cercs (polluted area in Spain), where there is a coal-fired power plant that emanates SO2, NOx, and particles, and the area of St. Jaume de Frontanya (nonpolluted area) located 40 km from the area of Cercs with similar climatology, relief, and altitude, but without air pollution. The results showed that there was a significant decrease in the erythrocyte count, and an increase in erythrocyte size in specimens from the polluted area. An increase in pre-albumines and a decrease in beta-globulines in Emberiza cia was observed, while an increase in transaminases (GOT and GPT), and a decrease in weight in Turdus merula from the polluted zone was observed.

Air Pollutants↗
PubMed1996

Effects of air pollution on hematological and plasma parameters in Apodemus sylvaticus and Mus musculus.

The effects of atmospheric air pollution on some hematological and plasma parameters, activity, and food and water consumption in Apodemus sylvaticus (wood mouse) and Mus musculus (mouse) were studied. The studies were undertaken in the area of Cercs (polluted area in Spain), where there is a coal-fired power plant that emanates SO2, NOx, and particles, and the area of St. Jaume de Frontanyà (nonpolluted area), located 40 km from the area of Cercs, with similar climatology, relief, and altitude, but without air pollution. Apodemus sylvaticus were captured in the field and Mus musculus were placed in cages in both studied areas. The results showed that there is a significant decrease in hematocrit, and a significant increase in leucocyte number, mean corpuscular hemoglobin concentration, osmolality, and gamma-globulin in Mus musculus, and a decrease in albumin (%) and albumin/globulin index in Apodemus sylvaticus. A negative correlation between hematocrit values and pollution was found. In mice placed in cages in the polluted area a slight but significant decrease in water and food consumption, and slower activity, was observed. The results suggest that pollution could induce a decrease in water and food consumption, which may be due to an observed reduction in activity.

Air Pollutants↗
PubMed1996

Acoustic analysis of snoring sound in patients with simple snoring and obstructive sleep apnoea.

Snoring, a symptom which may indicate the presence of the obstructive sleep apnoea syndrome (OSA), is also common in the general population. Recent studies have suggested that the acoustic characteristics of snoring sound may differ between simple snorers and OSA patients. We have studied a small number of patients with simple snoring and OSA, analysing the acoustic characteristics of the snoring sound. Seventeen male patients, 10 with OSA (apnoea/hypopnoea index (AHI) 26.2 events x h(-1)) and seven simple snorers (AHI 3.8 events x h(-1)), were studied. Full night polysomnography was performed and the snoring sound power spectrum was analysed. Spectral analysis of snoring sound showed the existence of two different patterns. The first pattern was characterized by the presence of a fundamental frequency and several harmonics. The second pattern was characterized by a low frequency peak with the sound energy scattered on a narrower band of frequencies, but without clearly identified harmonics. The seven simple snorers and two of the 10 patients with OSA (AIH 13 and 14 events x h(-1), respectively) showed the first pattern. The rest of the OSA patients showed the second pattern. The peak frequency of snoring was significantly lower in OSA patients, with all but one OSA patient and only one simple snorer showing a peak frequency below 150 Hz. A significant negative correlation was found between AHI and peak and mean frequencies of the snoring power spectrum (p<0.0016 and p<0.0089, respectively). In conclusion, this study demonstrates significant differences in the sound power spectrum of snoring sound between subjects with simple snoring and obstructive sleep apnoea patients.

Acoustics↗
PubMed1996

[Intravitreal ganciclovir in cytomegalovirus retinitis in AIDS].

A retrospective study was made of 26 patients with AIDS who initially presented with retinitis as the only clinical manifestation of cytomegalovirus infection (39 eyes). Sixty-five induction or re-induction therapeutic courses were administered with intravitreal ganciclovir. The efficiency rate of therapy was 93.8%. Thirty-eight maintenance therapeutic courses (200 micrograms/week) were evaluated. The non-compliance rate was 23%. Bilateral retinitis occurred in 44.4% of cases. The systemic administration of therapy had to be substituted for the intravitreal administration in 32% of patients during the clinical course of their conditions. The mean survival rate was 9.5 months. Both retinal detachment and vitreal hemorrhage occurred in 5% of patients. When retinitis is the first clinical manifestation of cytomegalovirus infection, therapy with intravitreal ganciclovir is efficacious to inactivate lesions. Although bilateral retinitis and extraocular dissemination are common, the mean survival rate is high.

Acquired Immunodeficiency Syndrome↗
PubMed1996

[Pseudomonas spp. infections in patients with HIV infections].

BACKGROUND: The aim of this study was to describe the characteristics of the infections by Pseudomonas spp. observed in patients with HIV infection in Spain. METHODS: A retrospective study was performed of the isolations of Pseudomonas spp. in microbiologic samples of patients with HIV infection in three hospitals from Mallorca, Spain, since 1986. RESULTS: Twenty-nine patients with some positive culture for Pseudomonas were reviewed. In 20 cases the infection presented in advanced stages of the disease when the patient fulfilled AIDS criteria. The most frequent foci in both community acquired and nosocomial infection was respiratory (16 and 3 cases, respectively). Fifty percent of the cases presented bacteremia. The classically described predisposing factors for infection by this germ were presented in 19 patients. Pseudomonas aeruginosa was the most frequently isolated type (22 cases). Only 5 patients received the appropriate treatment on admission. Clinical cure was achieved in 23 patients, with recurrence being observed in 10. Five patients died in relation to the infection. CONCLUSIONS: Infections by Pseudomonas spp. in Spain appear to have increased in frequency in patients with HIV infection in the last decade. These infections appear in advanced phases of the disease and mainly involve the lung, with high rates of bacteremia and a high number of recurrence. Empiric treatment of patients with advanced HIV infection with suspicion of bacterial infection should include antipseudomonic drugs.

Adult↗
PubMed1996

[Fever of unknown origin in patients with HIV infection].

BACKGROUND: The aim of the study was to describe the etiology and clinical characteristics of fever of uncertain origin (FUO) among HIV-infected patients. METHODS: Prospective analysis of 35 episodes of FUO in HIV-infected patients from Balearic Islands that were studied through established guidelines. RESULTS: Most patients were at advanced stages of HIV-1 infection (mean CD4 cell count, 60/mm3). Mean duration of fever until diagnosis was 57 days. Average time of hospitalization until etiological diagnosis of FUO was 26 days (range: 8-127 days). The cause of FUO was identified in 33 cases (94%). Tuberculosis accounted for 18 cases (51%) and visceral leishmaniasis for 8 cases (23%). Other opportunistic infections were the cause of FUO in 8 cases (17%). In one patient, fever was due to Kaposi's sarcoma. Two patients died while febrile, without and identified etiology. Four patients had more than one cause that could contribute to FUO. Imaging techniques that yielded more diagnostic information were abdominal ultrasonography and serial chest X-ray. Leishmania serology and tuberculin skin test showed a high specificity but low sensitivities. Invasive procedures with a highest diagnostic field were fine needle aspirate of lymph nodes, and liver biopsy. CONCLUSIONS: FUO is more frequent in advanced stages of HIV disease. In our area, FUO is caused primarily by endemic opportunistic infections specially TB and visceral leishmaniasis, and rarely can be attributable to HIV or neoplastic diseases.

AIDS-Related Opportunistic Infections↗
PubMed1995

[Changes in the natural history of AIDS in patients from Mallorca and Ibiza: 1986-1992].

BACKGROUND: Longitudinal follow-up studies in patients with human immunodeficiency virus (HIV) infection and AIDS, which are fundamental for the knowledge of variations the natural history of this disease, have generally been carried out by Public Health Departments and in populations in which homosexual males predominate. The aim of the present study was to analyze the changes in the natural history of the patients diagnosed with AIDS in the islands of Mallorca and Ibiza. METHODS: A prospective study of the adult patients diagnosed with AIDS in Mallorca and Ibiza, from 1986 to 1992 was performed. RESULTS: The annual incidence of the cases of AIDS increased throughout the study. The mean age of the patients did not vary, and neither did that in relation to sexes. A progressive decrease was observed in CD4 lymphocytes at the time of diagnosis (from 0.168 x 10(9)/l in 1986 to 0.079 x 10(9)/l in 1992). There was an increase in heterosexual transmission patients with no known risk factors also increased over the period studied. The incidence of extrapulmonary tuberculosis decreased both as the form of presentation and in its global frequency. Pneumonia by Pneumocystis carinii increased mainly as a initial feature. The median survival was 547 days and did not vary significantly throughout the study. CONCLUSIONS: The epidemiologic and clinical study of AIDS in Mallorca and Ibiza, Spain is similar to that observed in other Mediterranean regions. The incidence of extrapulmonary tuberculosis has decreased.

AIDS-Related Opportunistic Infections↗
PubMed1994

A straightforward method for purification of myo-inositol 1,3,4,5,6-pentakisphosphate from avian erythrocytes for subsequent application in studies on hemoglobin allosteric effect.

myo-Inositol 1,3,4,5,6-pentakisphosphate (Ins-P5) is the main allosteric effector of hemoglobin in avian erythrocytes. Molecular studies on the functioning of hemoglobin have frequently been performed with the hexaphosphate form of inositol, since it is difficult to obtain Ins-P5 of appropriate purity and in sufficient quantity for oxygen-affinity studies. This paper provides a detailed description of a method for adequate isolation of Ins-P5 from avian erythrocytes. The method is based on fractionation of erythrocyte organic phosphates by chromatography. The fractions corresponding to the peak of Ins-P5 were retained for further purification and concentration. This process includes gel filtration, cation-exchange chromatography, and lyophilization. At the end of the process about 15 mg of Ins-P5, free from other organic phosphates or salts, was obtained from 45 ml of pigeon blood. Trials performed on avian stripped hemoglobin solutions with Ins-P5 obtained in this way confirm that this phosphate is the main factor responsible for the decrease in oxygen affinity in intact erythrocytes, and that it is preferable to Ins-P6 for hemoglobin oxygen-affinity studies.

Allosteric Site↗
PubMed1994

Hematological, electrolyte, and biochemical alterations after a 100-km run.

Seven well-trained male long-distance runners were studied during a 100-km road race. Hematologic parameters, plasma electrolytes, glucose, lactate, urea, and creatinine content in plasma and the activity of the enzymes gamma-glutamyltransferase and creatinine kinase were determined before and after the race. A slight increase in hematocrit was found after the race, although the red blood cell count and hemoglobin concentration remained unchanged. Further, a significant rise in the number of white blood cells, lymphocytes, and neutrophils was found after the race. Postrun concentrations of plasma sodium and potassium increased significantly from 142 +/- 7 to 161 +/- 7 mmol.L-1, and from 4.22 +/- 0.37 to 5.15 +/- 0.46 mmol.L-1 (p < 0.05), respectively. Plasma concentrations of lactate (1.29 +/- 0.31 vs. 3.57 +/- 1.22 mmol.L-1), urea (6.09 +/- 1.0 vs. 8.35 +/- 1.35 mmol.L-1), creatinine (73.4 +/- 3.5 vs. 117.6 +/- 19.4 mumol.L-1), plasma creatine kinase (91.1 +/- 25.1 vs. 2843 +/- 2341 IU.L-1), and gamma-glutamyltransferase (20.28 +/- 1.88 vs. 24.14 +/- 4.09 IU .L-1) increased significantly (p < 0.05) after the run. It was concluded that during ultralong-distance races, acute renal dysfunction and muscle damage could contribute to the observed hypernatremia and hyperkalemia.

Adult↗
PubMed1993

Severe hypoxia decreases oxygen uptake relative to intensity during submaximal graded exercise.

The effect of severe acute hypoxia (fractional concentration of inspired oxygen equalled 0.104) was studied in nine male subjects performing an incremental exercise test. For power outputs over 125 W, all the subjects in a state of hypoxia showed a decrease in oxygen consumption (VO2) relative to exercise intensity compared with normoxia (P < 0.05). This would suggest an increased anaerobic metabolism as an energy source during hypoxic exercise. During submaximal exercise, for a given VO2, higher blood lactate concentrations were found in hypoxia than in normoxia (P < 0.05). In consequence, the onset of blood lactate accumulation (OBLA) was shifted to a lower VO2 (VO2 1.77 l.min-1 in hypoxia vs 3.10 l.min-1 in normoxia). Lactate concentration increases relative to minute ventilation (VE) responses were significantly higher during hypoxia than in normoxia (P < 0.05). At OBLA, VE during hypoxia was 25% lower than in the normoxic test. This study would suggest that in hypoxia subjects are able to use an increased anaerobic metabolism to maintain exercise performance.

Adult↗
PubMed1993

[Etiology of bacterial gastroenteritis in patients infected by the human immunodeficiency virus].

A comparative retrospective study was performed on the bacterial etiology of the diarrheal processes which affect a healthy cohort and those which affect HIV-positive patients. From 1988 to 1991, 10,230 coprocultures were obtained of which 27.3% were positive in the healthy cohort and 16.8% in the HIV-positive group. Of the 43 cases in the latter, 24 (12.2%) were adults and 18 (33.9%) were pediatric patients. The primary enteropathogenic microorganism isolated in the HIV-positive group were 17 (40.5%) S. enterica (I), 16 (38.1%) Campylobacter sp., and 9 (21.4%) aeromonas sp. Even though the overall percentage of enteropathogen detection hardly showed any differences between the two groups, it is worth mentioning that there was a certain predominance of diarrheas due to S. enterica (I) in the healthy cohort as compared to the incidence of diarrheas due to Campylobacter sp. and Aeromonas sp. in HIV-positive patients. There does not appear to be strong differences between the incidence of the various enteropathogens in the two groups, perhaps a simple reflection their geographic and local prevalence.

Adolescent↗