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M Diaz

Publications and source records attributed to M Diaz.

At least 91 records · Page 5Linked to original sources
PubMed1993

Evaluation of monoclonal antibodies with specificity for the human platelet HPA-1 allotypes.

Two mouse monoclonal antibodies have been characterized. Both antibodies specifically recognized the amino acid sequences which are responsible for the presence of the HPA-1a and HPA-1b alloantigens at the surface of human platelet. The monoclonality allied with an exquisite specificity of these antibodies allow a perfect typing of platelet HPA-1 status. A fast and reliable Elisa assay which fulfills all the needs and requirements of hematology laboratories has been set up and is described here. The Elisa assay has been tested on a population of 689 blood donors. The results agreed with the known phenotypic frequencies of the HPA-1 alloantigens.

Amino Acid Sequence↗
PubMed1993

[Endoscopic papillotomy and extraction of bile duct calculi in patients with gallbladder in situ and cholelithiasis].

Cholecystectomy with surgical papillotomy is a prolonged procedure with significant morbidity and mortality. In patient stay is usually extended. Occasionally the bad general conditions and the advanced age of the patients contraindicate surgical procedures. Eventually, the drainage of the biliary ducts is inevitable. For this reason, since 1983, we are performing the endoscopic papillotomy and extraction of stones from the bile duct in patients with choledocholithiasis and cholelithiasis. Cholecystectomy was performed only in cases with real necessity. Ninety one patients, 26 men and 65 women, between 25 and 82 years, have been submitted to this procedure in our department. Cholecystectomy was performed in 52 cases after 24 to 72 hours post-papillotomy. Due to acute cholecystitis 12 patients had to be operated after a period of 2 months to 2 years. No cholecystectomy was performed in 27 patients, they are still asymptomatic. Then were no mortality related to the method.

Adult↗
PubMed1992

Time-resolved fluorescence study of human recombinant interferon alpha 2. Association state of the protein, spatial proximity of the two tryptophan residues.

Human recombinant interferon alpha 2 belongs a to family of proteins active against a wide range of viruses. It contains two tryptophan residues located at positions 77 and 141 in the peptide sequence. The fluorescence emission spectrum of these tryptophan residues displays a maximum at 335 nm. The fluorescence intensity decay is described by one broad excited-state-lifetime population centered around a value of 1.7 ns (full width at half maximum, 1.5 ns). These observations suggest that in the native protein, both tryptophan residues emit from similar environments, not directly exposed to the surrounding solvent. The anisotropy decay is essentially biexponential. The correlation-time value characterizing the Brownian rotation of the protein varies linearly with the viscosity/temperature ratio. The calculated hydrodynamic volumes are compatible with the existence of a dimer and a tetramer, at pH 5.5 and 9.4, respectively. Addition of urea at pH 5.5 disrupts the dimer and modifies to some extent the excited-state-lifetime distribution which becomes more heterogeneous. Disulfide-bond reduction also dissociates the dimer and leads to a highly heterogeneous fluorescence-intensity decay with four excited-state-lifetime populations. An opening of the local structure in the Trp region of the protein is likely to occur in these conditions. The fast-anisotropy-decay components can be due to either fast rotation or energy transfer between the indoles. Close proximity of the two Trp residues (less than 1 nm) is suggested from steady-state and time-resolved fluorescence-anisotropy measurements in vitrified medium [95% (by mass) glycerol at -38 degrees C]. This suggestion is in agreement with the recently published three-dimensional structure of the homologous protein murine interferon beta [Senda, T., Shimazu, T., Matsuda, S. Kawano, G., Shimizu, H., Nakamura, K. T. & Mitsui, Y. (1992) EMBO J. 11, 3193-3201].

Fluorescence Polarization↗
PubMed1992

Effect of a zinc-fortified formula on immunocompetence and growth of malnourished infants.

This study attempted to define the possible contribution of zinc nutrition to immunocompetence and growth in severely malnourished infants. The effect of zinc supplementation was evaluated in marasmic infants during nutritional rehabilitation by using a controlled double-blind design in which 19 infants fed a zinc-fortified formula were compared with 20 infants fed the same non-supplemented formula. Evaluation of immunocompetence, growth, and zinc, copper, and iron status was performed on admission and at 30, 60, and 105 d of nutritional rehabilitation. Although energy intake was similar in both groups, the zinc-supplemented infants had significantly higher linear growth gain, and their immune function improved as demonstrated by conversion of their delayed hypersensitivity skin reactions, enhanced lymphoproliferative response to PHA, and increased salivary IgA concentrations. Thus, the use of a zinc-fortified formula during nutritional rehabilitation can prevent the development of zinc deficiency and improve growth and immune function.

Copper↗
PubMed1992

A Pan-American 5-year study of fluconazole therapy for deep mycoses in the immunocompetent host. Pan-American Study Group.

Eighty-eight immunocompetent patients with deep mycoses from eight countries were evaluated with the same protocol for efficacy of fluconazole monotherapy. Entry doses were raised from 100 to 400 mg as safety was shown in initial cohorts, and dosages up to 2,400 mg daily and durations up to 44 months were studied. Results were very similar in different countries. Twenty-seven of 28 evaluable patients with paracoccidioidomycosis, 13 of 19 with sporotrichosis, 14 of 16 with coccidioidomycosis, and eight of eight with histoplasmosis demonstrated objective responses to therapy, as did one patient each with zygomycosis and alternariosis. For these patients, relapses have been unusual thus far. In contrast, one patient with chromoblastomycosis responded but relapsed, and six did not respond; one patient with mycetoma responded but relapsed, and two did not respond. The drug was well tolerated by patients, including six who received intravenous therapy. In vitro susceptibility tests suggested that clinical response was correlated with susceptibility but that resistance did not preclude clinical response. Fluconazole therapy appears efficacious for several deep mycoses; dosages of greater than 200 mg daily may be needed for some diseases. The further evaluation of fluconazole for these entities is warranted.

Adolescent↗
PubMed1992

Prediction of malignant hyperthermia susceptibility in low-risk subjects. An epidemiologic investigation of caffeine halothane contracture responses. The North American Malignant Hyperthermia Registry.

The most commonly used laboratory test for predicting malignant hyperthermia susceptibility is the caffeine halothane contracture test. However, the specificity and sensitivity of proposed North American diagnostic guidelines for this test have never been evaluated in a large, human study population. Therefore, the authors conducted a multiinstitutional, prospective study of skeletal muscle contracture responses in a subject population at low risk for malignant hyperthermia susceptibility to help determine the specificity of the proposed guidelines. Subjects were selected arbitrarily from a population of patients undergoing surgery unrelated to performance of a diagnostic muscle biopsy. Subjects were admitted to this study and were presumed nonsusceptible if there was no evidence of any of the following malignant hyperthermia risk factors: prior abnormal response to triggering anesthetic agents, myopathy, or family history of malignant hyperthermia susceptibility. The authors suggested rejection of the proposed diagnostic guidelines if an 85% specificity estimate among subjects could not be obtained. The authors analyzed the responses of 1,022 muscle fascicles, derived from 176 subjects, to the following: 1) separate administration of 3% halothane or incremental caffeine concentrations, or 2) the joint administration of 1% halothane and incremental caffeine concentrations. The following contracture results were obtained. First, for individual fascicles, 9.2% exceeded a greater than 0.7 g threshold for 3% halothane, 15.2% exceeded a greater than or equal to 0.2 g threshold for 2 mM caffeine, 32.4% exceeded a 1-g increase for less than 4 mM caffeine, 2.6% had a greater than 7% maximal increase in tension at 2 mM caffeine, and 63.5% had a "halothane caffeine-specific concentration" at less than or equal to 1 mM caffeine. Second, the percentages of subjects with 1 or more fascicles exceeding the proposed threshold were as follows: 45.8% for the four-component, 28.8% for the three-component, and 32.7% for the two-component contracture test. Third, the percentages of subjects with 1 or more fascicles exceeding the proposed threshold for both halothane and caffeine were as follows: 9.5% for 3% halothane and 2 mM caffeine, 2.0% for 3% halothane and 7% maximal increase in tension at 2 mM caffeine, and 11.0% for 1% halothane and 2 mM caffeine. Fourth, center-to-center differences were the major source of variation in the rate that subjects exceeded proposed thresholds. These data demonstrate that proposed diagnostic guidelines must be modified to improve specificity estimates before adoption by diagnostic centers.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Choledochoduodenal fistulas.

In 2,012 ERCP studies reviewed in the period between 1976 and 1989, we observed 14 choledochoduodenal fistulas found in the upper portion of the papilla of Vater. Two fistulas occurred spontaneously due to necrosis of the duodenal wall caused by stones located in the distal common bile duct above the sphincter of the papilla. In these two cases the stones were removed endoscopically. The twelve remaining cases were iatrogenic, caused during surgical papillotomy which resulted in a false tract. All patients showed raised AP and gamma GT. Eight had acute cholangitis, 7 were jaundiced, there was one case each of acute pancreatitis and chronic recurrent pancreatitis. Nine patients had stones located in the distal common bile duct. In eight cases it was possible to cannulate the papillary opening and do a papillotomy thereby connecting the fistulous orifice with the opening of the papilla. The other patient was treated surgically. Two patients had papillary stenosis. One was successfully treated with papillotomy through the papillary opening. In the other, the fistulous orifice was joined with the papillary opening using a diathermy scalpel. This patient suffered a posterior duodenal wall perforation. One patient with acute pancreatitis and common bile duct stones distal to the fistula improved with papillotomy and stone removal. The patient with chronic recurrent pancreatitis without lithiasis refused any form of treatment.

Ampulla of Vater↗
PubMed1991

Evidence of infection with organisms producing Shiga-like toxins in household contacts of children with the hemolytic uremic syndrome.

We conducted a prospective study in 87 household contacts of 51 children with hemolytic uremic syndrome to determine the frequency of infection with Shiga-like toxin-producing bacteria. Gastrointestinal tract symptoms occurred in only 1 of 87 contacts. Free fecal toxin was detected in 25 of 64 (39%) of the household members. Neutralization with specific antisera to Shiga-like toxins I and II (SLT-I, SLT-II) revealed that in 6 of these household contacts only SLT-I was present in stool, in 10 only SLT-II was present and in 9 both toxins were found. Thirty-three percent of the hemolytic uremic syndrome families in which 2 or more members were studied had more than 1 household member with free fecal toxin in stool. None of the household contacts was found to have E. coli O157:H7 in feces. Serum samples were available in 77 household contacts; 75% (58 of 77) had serum neutralizing titers of greater than or equal to 1:4 to 1 or both toxins. In those contacts for whom paired sera were available, seroconversion was found in 10 of 24 (42%). These data show that household contacts of children with hemolytic uremic syndrome are commonly colonized with Shiga-like toxin-producing E. coli and seroconversion to Shiga-like toxins occurs frequently in family members of children with hemolytic uremic syndrome.

Adult↗
PubMed1991

Isolation and characterization of Schizosaccharomyces pombe mutants defective in cell wall (1-3)beta-D-glucan.

Schizosaccharomyces pombe thermosensitive mutants requiring the presence of an osmotic stabilizer to survive and grow at a nonpermissive temperature were isolated. The mutants were genetically and biochemically characterized. In all of them, the phenotype segregated in Mendelian fashion as a single gene which coded for a recessive character. Fourteen loci were defined by complementation analysis. Studies of cell wall composition showed a reduction in the amount of cell wall beta-glucan in three strains (JCR1, JCR5, and JCR10) when growing at 37 degrees C. Galactomannan was diminished in two others. Strains JCR1 and JCR5, with mutant alleles cwg1-1 and cwg2-1, respectively, were further studied. The cwg1 locus was mapped on the right arm of chromosome III, 18.06 centimorgans (cM) to the left of the ade5 marker; cwg2 was located on the left arm of chromosome I, 34.6 cM away from the aro5 marker. (1-3)beta-D-Glucan synthase activities from cwg1-1 and cwg2-1 mutant strains grown at 37 degrees C were diminished, as measured in vitro, compared with the wild-type strain; however, Km values and activation by GTP were similar to the wild-type values. Mutant synthases behaved like the wild-type enzyme in terms of thermostability. Analyses of round shape, lytic behavior, and low (1-3)beta-D-glucan synthase activity in cultures derived from ascospores of the same tetrad showed cosegregation of all these characters. Detergent dissociation of (1-3)beta-D-glucan synthase into soluble and particulate fractions and subsequent reconstitution demonstrated that the cwg1-1 mutant was affected in the particulate fraction of the enzymatic activity while cwg2-1 was affected in the soluble component. The antifungal agents Papulacandin B and Aculeacin A had similar effects on the enzymatic activities of the wild type and the cwg2-1 mutant strain, whereas the cwg1-1 mutant, when growing at 37 degrees C, had a more inhibitor-resistant (1,3)beta-D-glucan synthase. It is concluded that the cwg1+ and cwg2+ genes are related to (1,3)beta-D-glucan biosynthesis.

Aminoglycosides↗
PubMed1991

Itraconazole in the treatment of coccidioidomycosis.

Sixteen patients with coccidioidomycosis were treated with itraconazole for one year. Sixteen suffered from pulmonary coccidioidomycosis, two of them had associated mediastinal lesions, and one suffered from skin coccidioidomycosis. The daily dose used was 400 mg during the one-year period. Patients were clinically evaluated every month and tested for mycosis every three months. All patients except for one showed negative cultures on the third month after treatment began. Effectiveness achieved was excellent in eight patients (50 percent); a very good response was found in seven patients (44 percent); no response was seen in one patient (6 percent). There were four (25 percent) relapses and one dropout. Side effects seen were high blood pressure (19 percent) and lower limb edema (6 percent), which was temporary and at no time required discontinuing the drug therapy. We believe that itraconazole is an effective drug to treat coccidioidomycosis with a wide safety margin. It is well tolerated, and the incidence of relapses was low.

Adult↗
PubMed1991

Acyclovir resistant genital herpes virus infection in a patient with AIDS.

Three acyclovir resistant strains of HSV-2 were isolated from mucoulcerative lesions in a patient suffering from AIDS in whom the oral and intravenous acyclovir treatment was unsuccessful. All the isolates were classified by monoclonal antibodies and showed no differences in DNA restriction patterns.

Acquired Immunodeficiency Syndrome↗
PubMed1991

[Hygiene habits at the family level and typhoid].

We studied the relation of habits related to the fecal-oral cycle and incidence of typhoid fever in children attending the school system for 1 to 2 years and in their families. The goal was to identify a predictor to detect families at risk for typhoid fever. A sample of 80 school-mother dyads, 40 of high and 40 of low socio-economic status was studied. 20 children in each group had had typhoid fever. Logistic regression analysis allowed to identify dirty edges of the toilet bowl and nail eating habits as highly specific (97%) and sensitive (82%) index of risk. The predictor held both in high and low socio-economic groups and could be used to identify families at risk of developing typhoid fever.

Adult↗
PubMed1991

Translocation (Y;19)(q12;q13) and azoospermia.

An azoospermic male with a 46,X,t(Y;19)(q12;q13) karyotype is described. The comparison with 12 similar cases reveals that the Y breakpoints are usually on the long arm whereas the autosomal ones seem to be at random. Since a premeiotic origin is inconsistent with the arrest at diakinesis seen in those cases with meiotic studies, we postulate that a balanced t(Y;A) arises either via a chromatid exchange in the meiotic interphase or through a chromosome exchange in spermiogenesis or at the one cell stage of the zygote.

Adult↗
PubMed1989

Cord blood lipoprotein-cholesterol: relationship birth weight and gestational age of newborns.

Umbilical plasma levels of lipoproteins-cholesterol were measured in 60 premature (less than 37 weeks), 60 small for gestational age (SGA, greater than 37 weeks), and 60 full term newborns (greater than 37 weeks) to ascertain the relationship between gestational age, infant's weight and concentration of plasma lipoprotein cholesterol. Umbilical levels of total cholesterol (TC), unesterified cholesterol (UC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) in premature newborns were significantly higher (P less than .001) than in term infants. The levels of TC, UC, HDL-C and very low density lipoprotein cholesterol (VLDL-C) were substantially higher (P less than .05) in umbilical cord plasma of SGA newborns than in cord plasma of full term newborns. Lecithin:cholesterol acyltransferase activity in cord plasma was indirectly assessed by measuring the ratio of esterified cholesterol to unesterified cholesterol (CE/UC). This ratio was significantly lower (P less than .01) in preterm and SGA than in full term newborns. In addition, plasma TC, UC, LDL-C and HDL-C levels were inversely correlated with gestational age of newborns. By contrast, CE/UC ratio had an inverse correlation with gestational age and HDL-C of the newborns. These findings suggest that the levels of TC in newborns are regulated by the uptake of LDL-C by the fetal adrenal and, additionally, by the lecithin:cholesterol acyltransferase (LCAT) activity of newborn plasma. Only by careful follow-up of hyperlipidemic neonates can the true incidence of familial hyperlipoproteinemia and the value of early diagnosis be assessed.

Birth Weight↗
PubMed1989

Growth failure prediction in Chile.

The purpose of this investigation was to develop screening instruments for the prediction of infants' growth failure. Biological and social variables of subjects attending public clinics in Santiago, Chile, were prospectively collected and screened as possible risk factors of being underweight/age at the end of the first year of life using three methodologies. Methodologies used were: simple relative risk, logistic regression, and classification and regression trees. As judged by sensitivity and specificity properties, the screening instrument developed by the latter methodology is much better than the other two.

Chile↗