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M Rodríguez

Publications and source records attributed to M Rodríguez.

At least 343 records · Page 19Linked to original sources
PubMed1991

The relationship between Q gamma and Ca release from the sarcoplasmic reticulum in skeletal muscle.

Asymmetric membrane currents and fluxes of Ca2+ release were determined in skeletal muscle fibers voltage clamped in a Vaseline-gap chamber. The conditioning pulse protocol 1 for suppressing Ca2+ release and the "hump" component of charge movement current (I gamma), described in the first paper of this series, was applied at different test pulse voltages. The amplitude of the current suppressed during the ON transient reached a maximum at slightly suprathreshold test voltages (-50 to -40 mV) and decayed at higher voltages. The component of charge movement current suppressed by 20 microM tetracaine also went through a maximum at low pulse voltages. This anomalous voltage dependence is thus a property of I gamma, defined by either the conditioning protocol or the tetracaine effect. A negative (inward-going) phase was often observed in the asymmetric current during the ON of depolarizing pulses. This inward phase was shown to be an intramembranous charge movement based on (a) its presence in the records of total membrane current, (b) its voltage dependence, with a maximum at slightly suprathreshold voltages, (c) its association with a "hump" in the asymmetric current, (d) its inhibition by interventions that reduce the "hump", (e) equality of ON and OFF areas in the records of asymmetric current presenting this inward phase, and (f) its kinetic relationship with the time derivative of Ca release flux. The nonmonotonic voltage dependence of the amplitude of the hump and the possibility of an inward phase of intramembranous charge movement are used as the main criteria in the quantitative testing of a specific model. According to this model, released Ca2+ binds to negatively charged sites on the myoplasmic face of the voltage sensor and increases the local transmembrane potential, thus driving additional charge movement (the hump). This model successfully predicts the anomalous voltage dependence and all the kinetic properties of I gamma described in the previous papers. It also accounts for the inward phase in total asymmetric current and in the current suppressed by protocol 1. According to this model, I gamma accompanies activating transitions at the same set of voltage sensors as I beta. Therefore it should open additional release channels, which in turn should cause more I gamma, providing a positive feedback mechanism in the regulation of calcium release.

Animals↗
PubMed1991

Prevalence of antibody to hepatitis C virus in prospectively followed acute non-A, non-B hepatitis, from different epidemiological categories.

We have studied the prevalence of antibody against hepatitis C virus (anti-HCV) and its relation to the time of onset of the symptoms in 57 patients with acute non-A, non-B hepatitis: 16 post-transfusion, 25 drug addicts and 16 sporadic cases. In the 1st month after the onset of illness, anti-HCV was positive in 25% of patients with post-transfusion hepatitis, 44% of drug addicts and 25% of sporadic hepatitis. In the 3rd month this antibody was detected in 75%, 88% and 31.2%, and in the 6th month in 87.5%, 96% and 31.2%, respectively. The prevalence in the 3rd and 6th months was significantly higher in post-transfusion patients and drug addicts than in sporadic cases. In the 6th month the prevalence of anti-HCV in patients who progressed towards chronicity was also significantly higher than in those with acute resolving non-A, non-B hepatitis (94% vs 50%, p less than 0.001). These results show that HCV is probably the main agent in acute post-transfusion non-A, non-B hepatitis and in those occurring in drug addicts, and that in a high proportion of these patients the anti-HCV can be detected in the 3rd month after the beginning of the symptoms. On the other hand, the relation of hepatitis C virus with sporadic acute non-A, non-B hepatitis may be doubtful.

Acute Disease↗
PubMed1991

Occurrence and evolution of T3 fibroblast nuclei in healing tendons from growing chicks.

We applied immunocytochemical techniques including anti-triiodothyronine (T3) serum and microscopic analysis with colloid gold as the developer to identify the specific receptors of thyroid hormones located within the cell nucleus and between the heteroeuchromatin transition zone in 25 chicks. All chicks underwent tenotomy, followed by tenorrhaphy and immobilisation of the leg in plaster. There was a gradual decrease in the number of T3 receptors of collagen-forming fibroblasts as the tendons healed and their capacity to synthetize collagen diminished.

Animals↗
PubMed1991

[Percutaneous surgery in renal lithiasis. Current indications].

The indiscriminate use of extracorporeal shock waves in the treatment of urinary calculi has changed the place of percutaneous surgery in the treatment of renal lithiasis. The authors analyse current indications of PCN highlighting stone size. In their view, calculi greater than 2 cm warrant treatment by PCN since only 15-20% of patients are completely stone-free following a single session of ESWL. Attention is focussed on the staghorn calculus and the percutaneous approach. They describe the difficulty encountered in the fragmentation of the cystine calculus owing to its hardness and discuss the difficulties that may arise when using the percutaneous approach in patients with coexisting renoureteral conditions, in the treatment of lithiasis in children and in the obese patients.

Adult↗
PubMed1991

[Crohn's disease and amyloidosis. An association to be considered].

Two instances of Crohn's disease and amyloidosis are presented. The time elapsed between the diagnosis of Crohn's disease and that of amyloidosis was 2 and 8 years respectively. The first case had hepatosplenomegaly and moderate proteinuria; the other one, severe proteinuria in the nephrotic syndrome range. One patient had ileocolic disease and the other disease limited to the terminal ileum. In both cases renal functional was normal. The diagnosis was made by liver biopsy in one patient and by repeated renal biopsy in the one with nephrotic syndrome. Ileocolic resection was undertaken in one patient without complications. Screening for amyloidosis is important in patients with Crohn's disease.

Adult↗
PubMed1991

[Austrian's syndrome and infection with human immunodeficiency virus].

A case of a patient diagnosed of Austrian' syndrome associated to HIV infection is presented. Our aim is to highlight the frequent but not enough described association to pneumonia, endocarditis and meningitis caused by Streptococcus pneumonia to increased its knowledge and permit a correct and early treatment, improving the bad prognosis of this association.

Endocarditis, Subacute Bacterial↗
PubMed1991

[Changes in the number of and indications for laparoscopy at a general hospital from 1979 to 1989].

Laparoscopic examinations done during 1979-1989 have been reviewed. From 214 examinations done during the first year of the review, the number of laparoscopies has been steadily declining to 7 examinations in 1989. Indications have also changed during this decade. Laparoscopy does not any more belong to the first choice examinations for diagnosis. Its usefulness is restricted to highly selected individual cases.

Adolescent↗
PubMed1991

[Epidemic outbreak of methicillin-resistant Staphylococcus aureus in a general hospital. Preliminary report].

The incidence of MRSA infections in Spain had remained in a low level through the years, being MRSA usually less than 1.5% of all S. aureus isolates. Since October 1988, we have detected in our hospital a MRSA outbreak. The epidemic started in the surgical wards, and spread through the rest of the institution. The incidence of cases was higher in the ICU's, areas that act as "multipliers" of the outbreak. In spite of standard control measures, the total number of patients with MRSA was 245 in April 1990. We studied prospectively a sample of 100 MRSA patients: thirty-six percent were colonized and 46% infected. The more common source of infection was the lower respiratory tract and primary bacteremia. The infection-related mortality was 30%. Our MRSA strain belong to phage type III, and shows a characteristic multiple antibiotic resistant pattern, the MRSA strain is sensitive to vancomycin, fusidic acid, phosphomycin and cotrimoxazole. Over the entire outbreak period, the MRSA strain developed resistance to rifampin, imipenem-cilastatin and ciprofloxacin. In spite of all control measures implemented, the outbreak can not have been totally controlled, and MRSA is now an endemic pathogen in our institution. Therefore, major changes in therapeutic approach to nosocomial infections have been since then introduced.

Adult↗
PubMed1991

[Pseudothrombocytopenia: incidence, causes and methods of detection].

A prospective study of 20,761 routine clinical blood specimens was conducted in order to evaluate incidence and causes of pseudothrombocytopenia. All specimens were drawn in outpatient regimen and were analyzed by using the Coulter STKR autoanalyzer. The incidence of pseudothrombocytopenia was 0.15%, values clearly lower than others previously reported in hospitalized patients (1.9%). Of these patients, 72% had EDTA-induced platelet clumping sometimes associated to sodium citrate and 28% had spurious low platelet counts due to large platelets. No other causes of pseudothrombocytopenia were appreciated. It is important to remark that 49% of low platelet counts detected by the Coulter STKR have been due to pseudothrombocytopenia, and this instrument showed normal platelet and leukocyte histogram in 10% of these cases. Although time consuming these results confirm the necessity of preparation and examination of all blood smears presenting thrombocytopenia by automated cell-counting despite normal histograms. This approach would avoid erroneous diagnosis and dangerous medical or surgical therapy. A correlation of pseudothrombocytopenia with age, sex or clinical diagnosis were not found.

Adolescent↗
PubMed1990

Concomitant cisplatin chemotherapy and radiotherapy in advanced mucosal squamous cell carcinoma of the head and neck. Long-term results of the Radiation Therapy Oncology Group study 81-17.

One hundred twenty-four eligible patients with advanced mucosal squamous cell carcinoma of the head and neck were entered into a pilot study of concomitant cisplatin (100 mg/m2 given every 3 weeks for three doses) and standard irradiation. The initial complete response (CR) was 71% with an additional two cases salvaged by surgery for an overall 73% CR. When no keratin was identified in the histologic specimen (41 patients) the CR was 90%. The nasopharynx showed the best CR (89%) among the sites. At 4 years after treatment, the estimated locoregional tumor control rate was 43% and the survival, 34%. When no keratin was present in the specimen, the estimated locoregional control of tumor was superior (56% versus 38% with keratin identified, P = 0.02) and the estimated survival was also superior (48% versus 26%, P = 0.008). Acute treatment-related toxicities included one death due to renal damage and two patients with life-threatening renal damage. The delivery of radiotherapy was not altered. Late toxicity included necrosis -3%, fibrosis -4%, and one fistula. The results of this study justify a randomized trial for the comparison of this combination of cisplatin and radiotherapy versus radiotherapy alone in advanced mucosal carcinomas of the head and neck.

Carcinoma, Squamous Cell↗
PubMed1990

Production of a mouse monoclonal antibody against the alkaline phosphatase of adult Schistosoma mansoni.

This study describes the production and characterization of a monoclonal antibody (mAb) against the alkaline phosphatase of Schistosoma mansoni from splenocytes of chronically infected mice. Convenient selection of the mAb was achieved using the catalytic activity of the antigen in a developed enzyme-antigen immunoassay. The mAb was of the IgG1 subclass and it specifically recognized the alkaline phosphatase in adult worm sections by indirect immunofluorescence. Preincubation of the antibody with partially purified adult alkaline phosphatase did not result in inhibition of the enzyme activity and it did not mediate complement-dependent cytotoxicity against mechanically transformed schistosomula in vitro. The mAb was able to immunoprecipitate under reducing conditions a polypeptide of 65 kDa, similar in size to the monomeric subunit of the schistosome enzyme. The specificity of the mAb was assessed by competitive inhibition with antibodies of infected human sera in an immunoadsorption assay. Periodate treatment of the antigen resulted in altered electrophoretic mobility of alkaline phosphatase, which confirmed the presence of carbohydrate in the molecule, but this did not prevent binding by the mAb. Although the use of the mAb in capture assays for detection of circulating alkaline phosphatase in infected host sera was unsuccessful, the production of this antibody confirmed that the enzyme is exposed by adult worms to the host and that it is immunogenic; additionally, a monoclonal probe is available for further characterization of the structure and function of this important parasite surface molecule.

Alkaline Phosphatase↗
PubMed1990

Clinical isolate of a porinless Salmonella typhi resistant to high levels of chloramphenicol.

We studied a clinical isolate of Salmonella typhi (strain 1895) characterized by resistance to 200 micrograms of chloramphenicol per ml despite the absence of chloramphenicol-inactivating activity. The outer membrane protein profile analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated a deficiency of one of the major protein species which may serve as a porin for entry of chloramphenicol. When the strain was transformed with a plasmid encoding chloramphenicol acetyltransferase, chloramphenicol added to the culture was not inactivated, suggesting a drastic reduction of permeability towards the drug. Moreover, transformants bearing a plasmid coding for the Escherichia coli OmpF porin became considerably more susceptible to chloramphenicol (40 micrograms/ml). On the other hand, transformants carrying a plasmid encoding the Salmonella typhi ompC gene remained as resistant to the drug as the parental strain, even though they overexpressed OmpC. These findings indicate that the lack of OmpF plays a major role in the resistance to chloramphenicol in strain 1895.

Bacterial Outer Membrane Proteins↗