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Biomedical subjects

J Ramírez

Publications and source records attributed to J Ramírez.

At least 73 records · Page 4Linked to original sources
PubMed1995

Nucleotide sequence and chromosomal localization of the gene encoding the Old Yellow Enzyme from Kluyveromyces lactis.

A 6.6 kb genomic DNA fragment from the yeast Kluyveromyces lactis was isolated. Sequence analysis of this fragment revealed the presence of two incomplete open reading frames (ORFs) in one strand, one coding for the carboxyl terminus of the plasma membrane H(+)-ATPase and the other for the amino terminus of an unidentified product. In the complementary strand, a full-length ORF which encodes for a protein homologous to the yeast NADPH-dependent Old Yellow Enzyme was found. The deduced amino acid sequence of this ORF predicts a protein of 398 residues with 84% similarity in its full length to OYE1 from Saccharomyces carlsbergensis and OYE2 from Saccharomyces cerevisiae. In addition, an internal region showed considerable similarity to the bile acid-inducible polypeptide from Eubacterium sp., to the NADH oxidase from Thermoanaerobium brockii, to the trimethylamino dehydrogenase from bacterium W3A1 and to the estrogen-binding protein from Candida albicans, suggesting a functional or structural relationship between them. Inactivation of the KYE1 (Kluyveromyces Yellow Enzyme) gene by deletion of 0.6 kb fragment between positions +358 and +936 produced viable cells with a slight increase in their generation time. Haploid cells carrying the disrupted allele showed one-third of the NADPH oxidase activity, compared to wild-type cells. Southern blotting analysis of digested DNA and chromosomes separated by contour-clamped homogeneous electric field electrophoresis from K. lactis indicated that this is a single-copy gene and it is localized on chromosome II, whose molecular size has been estimated to be approximately 1.3 Mb.

Amino Acid Sequence↗
PubMed1995

Assessment of histopathologic changes in the colonic biopsy in acute graft-versus-host disease.

The authors reviewed 78 colonic biopsies from 63 patients undergoing bone marrow transplantation (BMT), 56 allogeneic and 7 autologous, to assess different morphologic changes related with intestinal acute graft-versus-host disease (A-GVHD). Only five biopsies were done before the 20th day after BMT. The authors studied the presence of ulcers and atrophy in the mucosa, the nuclear atypia, and inflammatory infiltrate in the surface epithelium, and the architectural abnormalities, as well as dilation of the glands, and the presence of crypt abscesses. The authors explored the glandular epithelium for apoptosis and intraepithelial lymphocytes. They examined the lamina propria for inflammatory infiltrate, especially for so-called "focal periglandular infiltrate (FPGI)," edema fibrosis, increase of capillary vessels and presence of muciphages and clusters of enterochromaffin cells. Cases were grouped according to clinical symptoms and histologic diagnosis of A-GVHD in skin or liver. Group A had 15 asymptomatic cases (control). Group B had 20 cases from asymptomatic patients with a histologically proven A-GVHD. Group C had 43 cases with gastrointestinal symptoms and histologically proven A-GVHD. Then, the relative frequency of every histologic feature previously described were compared in the different groups by means of an univariate analysis. Apoptosis of the glandular epithelium was found in 48 cases, two of them in patients carrying an auto-BMT. Focal periglandular infiltrate was found in 11 cases that was associated with apoptosis (P < .03, Fisher's exact test). In this series, the presence of FPGI was linked with finding apoptosis in a given specimen with a probability of 91%. Glandular architectural changes and dilation were also more frequent in group C than in groups A and B when compared in the univariate analysis.

Acute Disease↗
PubMed1995

Iron bioavailability from diets consumed by different socioeconomic strata of the Venezuelan population.

The iron bioavailability from three typical diets consumed by socioeconomic stratum IV (SES IV--working class) of the Venezuelan population was determined by the extrinsic label method. Although the iron content of the SES IV diets was about the same (250 mumol/d) as that of upper (SES I-III) and lower (SES V) socioeconomic strata diets, iron-replete subjects absorbed 43 and 61% more iron from the SES I-III diets than from the SES IV and V diets, respectively, and absorption from the main meal of the SES I-III diets was 100% greater. However, iron deficient subjects absorbed about the same amount of iron (45 mumol/d) from the SES IV diets as from the SES I-III diets. The SES I-III diets contained more iron absorption enhancers (ascorbic acid and meat protein) and less of the inhibitor phytate, than the SES IV and V diets. Iron absorption from the meals of four diets consumed at different times during the day was also measured. There was no significant difference in the percentage iron absorption from the same meals eaten in the morning after an overnight fast, and when eaten at the customary time of day.

Absorption↗
PubMed1995

A NADP-glutamate dehydrogenase mutant of the petit-negative yeast Kluyveromyces lactis uses the glutamine synthetase-glutamate synthase pathway for glutamate biosynthesis.

The activities of the enzymes involved in ammonium assimilation and glutamate biosynthesis were determined in wild-type and NADP-glutamate dehydrogenase (GDH) null mutant strains of Kluyveromyces lactis. The specific NADP-GDH activity from K. lactis was fivefold lower than that found in Saccharomyces cerevisiae. The glutamine synthetase (GS) and glutamate synthase (GOGAT) activities were similar to those reported in S. cerevisiae. The NADP-GDH null mutant was obtained by transforming the uraA strain MD2/1 with a linearized integrative yeast vector harbouring a 390 bp fragment of the NADP-GDH structural gene. This mutant grew as well as the parent strain on ammonium, but showed GS and GOGAT activities higher that those found in the wild-type strain, implying that the GS-GOGAT pathway could play a leading role in glutamate biosynthesis in K. lactis. Southern blotting analysis of K. lactis chromosomes separated by contour-clamped homogeneous electric field electrophoresis, indicated that the NADP-GDH structural gene is localized on chromosome VI.

Amino Acid Sequence↗
PubMed1995

Proton pumping and the internal pH of yeast cells, measured with pyranine introduced by electroporation.

The internal pH of yeast cells was determined by measuring the fluorescence changes of pyranine (8-hydroxy-1,3,6-pyrene-trisulfonic acid), which was introduced into the cells by electroporation. This may be a suitable procedure for the following reasons. (i) Only minor changes in the physiological status of the cells seemed to be produced. (ii) The dye did not seem to leak at a significant rate from the cells. (iii) Different incubation conditions produced large fluorescence changes in the dye, which in general agree with present knowledge of the proton movements of the yeast cell under different conditions. (iv) Pyranine introduced by electroporation seemed to be located in the cytoplasm and to avoid the vacuole, and therefore it probably measured actual cytoplasmic pH. (v) Correction factors to obtain a more precise estimation of the internal pH are not difficult to apply, and the procedure may be useful for other yeasts and microorganisms, as well as for the introduction of other substances into cells. Values for the cytoplasmic pHs of yeast cells that were higher than those reported previously were obtained, probably because this fluorescent indicator did not seem to penetrate into the cell vacuole.

Arylsulfonates↗
PubMed1995

Molecular cloning of the plasma membrane H(+)-ATPase from Kluyveromyces lactis: a single nucleotide substitution in the gene confers ethidium bromide resistance and deficiency in K+ uptake.

A Kluyveromyces lactis strain resistant to ethidium bromide and deficient in potassium uptake was isolated. Studies on the proton-pumping activity of the mutant strain showed that a decreased H(+)-ATPase specific activity was responsible for the observed phenotypes. The putative K. lactis PMA1 gene encoding the plasma membrane H(+)-ATPase was cloned by its ability to relieve the potassium transport defect of this mutant and by reversing its resistance to ethidium bromide. Its deduced amino acid sequence predicts a protein 899 residues long that is structurally colinear in its full length to H(+)-ATPases cloned from different yeasts, except for the presence of a variable N-terminal domain. By PCR-mediated amplification, we identified a transition from G to A that rendered the substitution of the fully conserved methionine at position 699 by isoleucine. We attribute to this amino acid change the low capacity of the mutant H(+)-ATPase to pump out protons.

Amino Acid Sequence↗
PubMed1995

Massive metastases from a lobular breast carcinoma from an unknown primary during pregnancy. A case report.

BACKGROUND: Carcinoma of the breast during pregnancy represents 2-5% of all breast cancers. The frequency and histopathologic spectrum of breast cancer are similar in pregnant and nonpregnant women. Infiltrating lobular carcinoma is one of the less understood types of breast cancer, and its metastatic pattern seems to be different from that of infiltrating ductal carcinoma. Breast neoplasms rarely present as cancer from an unknown primary site. CASE: A woman in the third trimester of pregnancy developed carcinoma massively metastatic to the bone marrow and liver from an unknown primary tumor. At 32 weeks' gestation a healthy male was delivered by cesarean section. The patient died 12 hours after delivery. The autopsy revealed an infiltrating lobular carcinoma, 1.5 cm, of the breast. CONCLUSION: Massive metastases from an occult lobular breast carcinoma in a pregnant woman are very rare. Diffuse metastatic spread, which often complicates or delays the diagnosis, is a characteristic pattern of infiltrating lobular carcinoma. Cancer from an unknown primary site during pregnancy is an exceptional finding. If a metastatic adenocarcinoma is diagnosed in a pregnant woman, a breast primary should be strongly suspected.

Adult↗
PubMed1994

Identification of a 20-kDa protein with calcium uptake transport activity. Reconstitution in a membrane model.

This paper presents results of experiments designed to further purify the membrane system involved in mitochondrial calcium transport. A partially purified extract, which transported calcium with a specific activity of 1194 nmol 45Ca2+/mg protein/5 min, was used to obtain mouse hyperimmune serum. This serum inhibited calcium uptake both in mitoplasts and in vesicles reconstituted with mitochondrial proteins containing cytochrome oxidase. Western blot analysis of the semipurified fraction showed that the serum recognized specifically two antigens of 75 and 20 kDa. Both antibodies were purified by elution from the nitrocellulose sheets and their inhibition capacity was analyzed. The antibody that recognized the 20-kDa protein produced a higher degree of inhibition than the other one.

Animals↗
PubMed1994

Idiopathic pulmonary-renal syndrome with antiproteinase 3 antibodies.

In this report, we describe a patient who developed acute renal failure and fatal pulmonary hemorrhage. Autopsy examination revealed pauci-immune necrotizing glomerulonephritis and pauci-immune hemorrhagic alveolar capillaritis. No evidence of granulomatous inflammation or vasculitis other than capillaritis was found in either lungs or kidneys. In addition, histopathologic examination of the upper respiratory tract, liver, spleen, digestive tract, and skeletal muscle was completely normal. The patient's serum sample disclosed antiproteinase 3 antibodies with an immunofluorescence titer of 1:1,600. Although there have been reports of patients with pulmonary-renal syndrome in association with antiproteinase 3 antibodies in the absence of a well-known vasculitic disease, we have not so far seen a case documented by a detailed autopsy study such as is presented here. In view of our findings and those of some other reports on this clinicopathologic condition, we suggest that this might represent a distinct form of vasculitis with exclusive capillary involvement.

Aged↗
PubMed1994

Fortification of precooked maize flour with coarse defatted maize germ.

The possibility of improving the dietary value of precooked maize flour through fortification with 11% coarse defatted maize germ was investigated. The results of tests in humans presented here show that the total iron absorption from the fortified preparation is similar to that from the precooked maize alone, but with the advantage of being richer in several nutrients: protein (25%), zinc (61%), potassium (47%) and magnesium (112%), as well as fiber (34%). Fortification lowers (by 20%) rather than raises the cost of the flour, and may be an important contribution to the diet of those populations where maize bread is a major component of the diet.

Absorption↗
PubMed1993

Further studies on the mechanism of action of gossypol on mitochondrial membrane.

1. In order to explore the mechanism of inhibition of hydroxylases involved in steroidogenesis, by gossypol, we studied the effect of this drug on adrenal cortex mitochondria, and compared it with those on kidney and heart. 2. The uncoupler effect of gossypol (collapse of delta psi and Ca2+ efflux) was found to be lower in adrenal cortex mitochondria than in kidney and heart mitochondria. 3. Gossypol produced more extensive changes on the membrane lipidic matrix (increase in the order parameter for 5-doxylstearic acid) in adrenal cortex mitochondria than in the other mitochondria studied. 4. The results described above indicate that the mechanism of inhibition of gossypol of steroidogenic adrenal enzymes could be attributed to an alteration of the lipidic matrix which, in turn, modifies protein function.

Adrenal Cortex↗
PubMed1993

[Transesophageal echocardiography: experience with the first 500 consecutive cases].

The results of all the transesophageal echocardiographies (TEE) performed between June 1989 and February 1992 are analyzed. Five hundred patients (240 male) with a median age of 57 years (range 13-88) were examined; during the same period, 5180 transthoracic echocardiographies were performed. TEE were requested for the following reasons: valvular prosthesis disfunction in 132 patients, rheumatic valvulopathy in 103, search for embolic origins in 97, study of congenital cardiopathies in 48, bacterial endocarditis in 35, aortic dissection in 25 and miscellaneous in 78. Among congenital cardiopathies there were 29 cases of interauricular communication and among miscellaneous cases, 9 patients with cardiac tumors. No major complications occurred. The imaging quality of this technique renders it specially important in the study of prosthesis disfunction, mitral valve analysis before valvuloplasty, detection of cardiac origins of emboli and infective endocarditis complications and anatomical and dynamic analysis of aortic dissection. It is concluded that TEE is a safe technique that provides high quality images and visualizes segments of the heart and great vessels formerly inaccessible with transthoracic echocardiography. It has enlarged the diagnostic capacity of echocardiography and improved the support of therapeutic decisions.

Adolescent↗
PubMed1993

[Thoracic actinomycosis. Presentation of 3 cases].

We have had the chance to follow three patients with thoracic actinomycosis in a relatively short period of time (18 months). They were three male patients, with chronic dental infections. The illness appeared as toxic syndrome and fever. In all three cases diagnosis was made through samples obtained through fibropticbronchoscopy. At the same time all of them evolved favorably to the antibiotic treatment (penicillin and/or tetracyclines) prescribed. We conclude that the diagnosis of thoracic actinomycosis should be suspected in those patients with a compatible clinical and radiological condition, and who has suffered previous weakening diseases and periodontal lesions.

Actinomycosis↗
PubMed1991

An energy-dependent efflux system for potassium ions in yeast.

An efflux of potassium ions was demonstrated in mutants of yeast cells lacking a functional high affinity carrier system for monovalent cations. This efflux showed the following characteristics: (a) It was stimulated by the presence of a substrate, either glucose or ethanol. (b) It was stimulated by several cationic organic molecules, such as ethidium bromide, dihydrostreptomycin, diethylaminoethyldextran, and also by trivalent cations, such as Al3+ and lanthanides; this stimulation also depended on the presence of a substrate. (c) K+ efflux was decreased in yeast mutants with decreased ATPase activity, which generated a lower membrane potential. (d) Although the efflux appeared to be of an electrogenic nature, producing hyperpolarization of cells, it was accompanied by the efflux of phosphate, probably as an anion partially compensating for the large amount of cations leaving the cell. (e) K+ efflux was also accompanied by an uptake of protons. (f) The efflux appeared more clearly in cells grown in YPD medium, and not in more complex media nor in the same YPD medium if supplemented with Ca2+ or Mg2+. Efflux of monovalent cations produced by Tb3+ and organic cationic agents was also demonstrated in wild type strains. This efflux system appears to be, at least partially, electrogenic, but seems to be also an exchange system for protons and to function as a symport with phosphate; it may be involved in the regulation of the internal pH of the cell, and appears to be regulated by its link to the energetic status of the cell, probably through the membrane potential.

Calcium↗