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Biomedical subjects

M Alvarez

Publications and source records attributed to M Alvarez.

At least 19 recordsLinked to original sources
PubMed1992

Modulation of P-glycoprotein phosphorylation and drug transport by sodium butyrate.

P-Glycoprotein (Pgp) expression in cell lines derived from tumors arising from cells which normally express Pgp can be increased by sodium butyrate and other differentiating agents. Although the Pgp level increased 25-fold after sodium butyrate treatment in SW620 human colon carcinoma cells, the intracellular accumulation of vinblastine, adriamycin, and actinomycin D increased rather than decreased. In contrast, colchicine showed the expected decrease in accumulation, as a result of increased efflux. Likewise, treatment of a Pgp-expressing multidrug-resistant SW620 subline with sodium butyrate resulted in active interference with Pgp function. This effect was partially reversed by phorbol esters with a resulting decrease in the accumulation of vinblastine, adriamycin, and actinomycin D. Sodium butyrate, while increasing Pgp levels, inhibited the phosphorylation of Pgp. Time course studies revealed a tight relationship between decreased Pgp phosphorylation and increased vinblastine accumulation after sodium butyrate treatment. Either treatment with phorbol esters or withdrawal of sodium butyrate increased Pgp phosphorylation while decreasing vinblastine accumulation. These studies suggest that the specificity of Pgp transport can be modulated by phosphorylation and that vinblastine, adriamycin, or actinomycin D transport, but not that of colchicine, is diminished after dephosphorylation by sodium butyrate.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

[Chronic granulomatous disease and pulmonary nocardiosis].

A 19-years-old male was admitted for left bilobar pneumonia. All microbiologic studies in blood and in several samples obtained by bronchoscopy were negative. The patient worsened progressively despite antibiotherapy of a wide spectrum. A fine needle transparietal puncture was performed. The cultures of the sample were positive for Nocardia asteroides, a positive catalase germ. Immunologic studies initiated after this time showed negative tetrazolium nitroblue test, the results of which led to the diagnosis of chronic granulomatous disease. This disease is very infrequent and the polymorphonuclear leukocytes are genetically incapable of producing peroxides whose absence impedes lysis of the positive phagocytic catalase germs with which a histologic reaction is produced in the form of granulomas from which the name of the disease is derived.

Adult↗
PubMed1992

New approach to the management of airway obstruction in "high risk" neonates.

Epignathus is a rare tumor of newborns that is associated with a high mortality secondary to airway obstruction in the neonatal period. Due to recent advances in prenatal ultrasound and magnetic resonance imaging techniques, accurate in utero diagnosis of this rare teratoma will enable the health care team to prepare for "emergency" management of a difficult airway. We present a case of a newborn with a large epignathus diagnosed prenatally who underwent tracheotomy with intact maternal-fetal circulation. After airway stabilization, maternal-fetal circulation was interrupted and the epignathus was successfully removed. To our knowledge, this is the first extrauterine surgical procedure successfully performed using this technique. A new approach to airway management in "high risk" neonates involving the cooperative efforts of pediatricians, neonatologists, anesthesiologists, and otolaryngologists is presented.

Airway Obstruction↗
PubMed1992

Morbidity of failed labor in patients with prior cesarean section.

OBJECTIVE: The aim of our study was to determine whether the reported increased morbidity associated with failed attempted vaginal birth after cesarean section is attributable to the presence of a uterine scar alone or to labor preceding a cesarean section. STUDY DESIGN: Primiparous women (N = 237) who underwent repeat cesarean section after a failed trial of vaginal birth after cesarean section were retrospectively compared with 1582 nulliparous women who underwent a primary cesarean section after a failed trial of labor. RESULTS: There were no significant differences in maternal or neonatal morbidity between the two groups except for an increase in the prevalence of thin meconium in patients undergoing primary cesarean section. CONCLUSION: Our results suggest that the presence of a previous cesarean section scar does not increase the overall baseline morbidity associated with cesarean section after labor.

Adult↗
PubMed1992

Beta-endorphin concentrations in fetal blood during the second half of pregnancy.

OBJECTIVE: Endogenous opiates may play a role in both fetal physiologic functions and the adaptation to intrauterine stress. However, our understanding of this role is hampered by an absence of data on circulating levels of these substances during fetal life. STUDY DESIGN: We measured serum beta-endorphin values with a radioimmunoassay in 81 paired fetal and maternal blood samples and 24 neonatal cord specimens. The former samples were uneventfully obtained from uncomplicated pregnancies between 18 and 39 weeks of gestation at the time of cordocentesis for prenatal diagnosis. RESULTS: Mean fetal beta-endorphin concentrations were significantly lower than beta-endorphin values from neonates (90.5 pg/ml [+/- 59.4] vs 228.4 pg/ml [+/- 166.2]; p less than 0.001), but significantly higher than mean maternal values (70.5 pg/ml [+/- 48.8]; p less than 0.02). Although fetal beta-endorphin levels decreased between 18 and 28 weeks' gestation, the correlation between fetal beta-endorphin values and gestational age was not significant (r = -0.193; p = 0.07). However, fetal beta-endorphin concentrations were significantly correlated with maternal values (Spearman's rank r = 0.47; p less than 0.001). CONCLUSION: These findings suggest that delivery or fetal adaptation to an extrauterine environment is associated with significant increases in beta-endorphin release. Moreover, although the fetal pituitary may be the primary source of circulating fetal beta-endorphin, a maternal or placental contribution cannot be excluded. Our data identify a physiologic range for fetal beta-endorphin concentrations.

Female↗
PubMed1992

Maternal characteristics, neonatal outcome, and the time of diagnosis of gestational diabetes.

OBJECTIVE: A study was undertaken to evaluate the yield of early, routine screening for gestational diabetes and to determine whether maternal characteristics and neonatal outcome differ according to the time of diagnosis. STUDY DESIGN: A total of 2776 women were screened before 24 weeks of gestation, and each was delivered of a singleton infant on the clinic service of Mount Sinai Hospital in New York City between January 1986 and January 1991. RESULTS: An abnormal glucose tolerance test was diagnosed in 102 women < 24 weeks and in 252 patients at > or = 24 weeks of gestation. Logistic regression analysis showed that the group diagnosed early was significantly older and more likely to have hypertensive disorders and low maternal weight gain and to require insulin treatment, compared with the group diagnosed late. No significant differences were evident in neonatal outcome. CONCLUSIONS: These data indicate that a sizable proportion of patients with gestational diabetes can be diagnosed early in pregnancy. The differences in maternal characteristics and insulin requirements between the early- and late-diagnosis groups also suggest heterogeneity of gestational diabetes or the possibility of preexisting impaired glucose intolerance in the early-diagnosis group.

Diabetes, Gestational↗
PubMed1992

Epidemiological survey of genes encoding aminoglycoside phosphotransferases APH (3') I and APH (3') II using DNA probes.

The epidemiological survey of APH (3') I and APH (3') II genes, at a time when the specific antibiotic pressure was very low, was carried out by DNA-DNA hybridization. The sample included 334 aminoglycoside resistant Gram-negative bacteria collected from patients of a General Hospital. Of these, 251 hybridized with the APH (3') I-probe and 19 with the APH (3') II-probe but only 190 strains showed high resistance levels (CIM greater than 64 micrograms/ml) for kanamycin, neomycin and paromomycin. These strains were isolated both from inpatients and outpatients with different infectious diseases. The APH (3') I-gene was dispersed among all the bacterial species and clinical specimens tested but the APH (3') II-gene was not found in Pseudomonas spp, Escherichia coli, Citrobacter freundii and Enterobacter cloacae, nor in infected catheters. Several plasmids of different sizes carrying APH (3') genes were detected among different bacteria. Plasmids along with transposable elements (the probes used in this work were developed from Tn906 and Tn5) and the high consumption of other antibiotics whose resistance is carried by these bacteria might be playing an important role in the maintenance and dispersion of APH (3') genes.

Aminoglycosides↗
PubMed1992

The severely anemic and hydropic isoimmune fetus: changes in fetal hematocrit associated with intrauterine death.

Hydrops caused by isoimmune hemolytic anemia is frequently associated with fetal death following intrauterine intravascular transfusion. To identify possible predictors of procedure-related fetal death, we examined changes in fetal blood volume and hematocrit resulting from the initial transfusion performed on 19 severely anemic, hydropic fetuses. Seven fetuses (36.8%) died at 24-72 hours after transfusion, but in no case was the procedure associated with fetal distress. There were no significant differences between fetuses who died and those who survived in terms of total volume of blood transfused, volume transfused as a percentage of total fetoplacental blood volume, hematocrit of transfused blood, post-transfusion hematocrit, umbilical vein pH, or gestational age at transfusion. Significant differences were noted between hydropic fetuses who died compared with those who survived in the mean pretransfusion hematocrit, 6.7% (+/- 2.0) versus 8.7% (+/- 1.6) (P = .03), and the relative increase in post- over pre-transfusion hematocrit, 5.5-fold (+/- 1.4) versus 3.5-fold (+/- 0.8) (P = .001). Stepwise logistic regression analysis confirmed that only the relative increase in hematocrit was predictive of fetal loss. Moreover, six of seven fetal deaths occurred when the relative increase in hematocrit was greater than fourfold, whereas ten of 12 surviving fetuses had relative increases of less than fourfold. We conclude that large, acute increases in fetal hematocrit following intrauterine transfusion are associated with substantial mortality in hydropic fetuses.

Anemia↗
PubMed1992

[Chagas disease with the acquired immunodeficiency syndrome. Clinical cases].

We report 2 patients with AIDS who developed Chagas infection, one with encephalitis, the other with acute myocarditis. The implications of immune depression for the manifestations and course of Chagas disease are discussed. Chagas disease should be considered in patients with AIDS who live in endemic zones and who develop cerebral or cardiac manifestations.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Hypoplastic pulmonary artery: an unusual entity mimicking pulmonary embolism during pregnancy.

Hypoplastic pulmonary artery is an unusual congenital malformation. We describe a case of hypoplastic pulmonary artery diagnosed during the third trimester of pregnancy. The clinical and radiologic features mimicked pulmonary embolism, including hemoptysis, chest pain, pleural effusion, mild hypoxemia, and a suggestive ventilation-perfusion scan. Accurate differentiation of this entity from pulmonary embolism is necessary to obviate the need for prolonged anticoagulation.

Adult↗
PubMed1992

[Pneumonia caused by non-opportunistic bacteria in patients infected with HIV. Incidence and evaluation of a non-invasive approach].

BACKGROUND: Pneumonia due to pathogenic bacteria is common in HIV infected patients. However, a global overview has not been yet performed and also the effectiveness of a non-invasive approach has not been tested. PATIENTS AND METHODS: An open study was conducted in 1989 including all HIV infected patients with a presumptive or definite diagnosis of bacterial pneumonia. Fiberoptic bronchoscopy procedures were used only in patients with a difficult diagnosis and/or problems in their clinical evolution. Clinical and biological data were compared among different etiologic groups, and their evolution was also recorded in relation with the use of non-invasive procedures. RESULTS: Among a total of 302 admissions of HIV infected patients, 113 developed a primary or secondary respiratory tract infection. Forty-three of those were bacterial pneumonia episodes. Etiologic diagnosis was achieved with non invasive methods in 18 cases (42%). Blood cultures were the most effective method used. Streptococcus pneumoniae was the most frequently identified microorganisms (9 cases, 21%). The identification of other bacteria was linked with more severe forms of disease regarding immunologic (leukopenia, p less than 0.001; T4 lymphopenia, p less than 0.05), and respiratory parameters (hypoxemia, p less than 0.05). Two deaths were directly related with pneumonia of known etiology. CONCLUSIONS: Bacterial pneumonia is the most frequent respiratory infection in HIV infected patients. An initial non-invasive approach yields a reasonable percentage of etiologic diagnosis and is not related with a poorer outcome.

Bacterial Infections↗
PubMed1992

[Parahemophilia. Study in a family of 3 generations].

Three generations of a family with congenital deficit of factor V are reported. Those subjects showing symptoms were heterozygous. The transmission of the disease appears to be autosomal recessive. From a clinical standpoint, the patients suffered moderate haemorrhages, mostly affecting mucosae, which became severe on occasions, chiefly after labour. Isolated factor V rates did not correlate with the severity of bleeding. The different variants reported in the literature are commented. Transfusion of fresh-frozen plasma seems and adequate therapeutical approach for this disorder.

Factor V Deficiency↗
PubMed1992

[Asplenia syndrome with duodenal stenosis].

We report a patient with asplenia syndrome. To our knowledge this is the first case described of asplenia syndrome with duodenal stenosis and no heart anomalies. An other important finding has been the absence of vomiting in her symptomatology.

Child↗
PubMed1991

Diagnostic potential of IgA coated Candida cells in mucous membrane candidiasis.

The significance of in vivo IgA coated yeast cells for the diagnosis of candidiasis of the oral and vaginal mucosal membranes was evaluated by direct immunofluorescence in 70 patients with or without clinical symptoms, shown to be positive for yeast growth in the cultural test. Most of the patients with clinically suspected candidiasis of the mucosal membranes gave positive results by serologic assays in contrast to the majority of symptomless patients. The diagnostic approach proved to be essentially consistent with the clinical signs, persistence of infection, response to antifungal therapy and quantitative cultural data.

Candida↗
PubMed1991

Characterization of two aminoglycoside-(3)-N-acetyltransferase genes and assay as epidemiological probes.

Two genes encoding for aminoglycoside-(3)-N-acetyltransferases (AAC(3)s) of different substrate patterns, present in multiresistance plasmids of hospital strains of Serratia marcescens and Escherichia coli isolated from urine, have been cloned and characterized. The first, aacC1 with AAC(3)I activity, contained a 531 base pair open reading frame which encodes a polypeptide of 177 aminoacids and 19,392 daltons, confirmed by minicell analysis. Its sequence differed from previously published work in four positions. Three of the changes did not alter the aminoacid sequence while the fourth was a substitution of an alanine by a proline. The second gene, an AAC(3)II encoded by aacC2, resulted from the translation of an 858 base pair open reading frame, which encoded a 286 aminoacid polypeptide of 31,574 daltons and was identical to those from plasmids isolated in Germany and the United States. However, the homology was broken in a position between the -10 and -35 promoter sequences, which resulted in different -35 hexanucleotides and levels of resistance conferred. The assay of both genes as molecular probes has revealed their specificity with respect to other aac genes, although their usefulness was limited in the case of aacC1 derived sequences to isolated plasmid DNA, since it hybridized under stringent conditions with chromosomal DNA of some strains of E. coli.

Acetyltransferases↗
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↗