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Biomedical subjects

S López

Publications and source records attributed to S López.

At least 127 records · Page 7Linked to original sources
PubMed1987

Synthesis in Escherichia coli and immunological characterization of a polypeptide containing the cleavage sites associated with trypsin enhancement of rotavirus SA11 infectivity.

About 45% of the rotavirus SA11 VP3 gene was inserted into a thermoinducible expression plasmid under the control of phage lambda PL promoter. The primary translation product predicted on the basis of the plasmid construction was a hybrid protein in which the 98 amino-terminal amino acids of phage MS2 polymerase were followed by amino acids 42 to 387 of the VP3 protein, which included the region containing the cleavage sites associated with trypsin enhancement of infectivity. On induction, a polypeptide that had the expected mol. wt. and contained VP3-related amino acid sequences as judged by immunological criteria, was synthesized to a level representing about 15% of the total bacterial protein. When a bacterial lysate enriched for the fusion polypeptide was injected into mice, it induced antibodies which inhibited haemagglutination and neutralized SA11 rotavirus infectivity.

Animals↗
PubMed1987

Insulin-related changes in the subcellular distribution of insulin receptors in intact rat liver: effects of acute hypoinsulinemia induced by diazoxide, somatostatin, and xylazine.

The effects of inhibitors of insulin secretion on the concentration of plasma insulin and on the subcellular distribution of hepatic insulin receptors have been examined in rats. Liver plasma membranes, Golgi fractions, and a total particulate fraction were prepared various times after the injection of diazoxide (10 mg), xylazine (0.5 mg), and somatostatin (20 micrograms as a bolus followed by a 20 micrograms/15-min infusion), solubilized by Triton X-100, and examined for specific insulin binding. Injection of each of these drugs caused a 4- to 8-fold decrease in plasma insulin concentration, and concomitantly, a 25-35% decrease in insulin binding to Golgi fractions; a 10% increase in insulin binding to plasma membranes also occurred in diazoxide-treated rats. Insulin binding to the total particulate fraction was unaffected. These changes achieved maximum by 10-30 min and underwent complete reversal in 1 h. The decrease in insulin binding to Golgi fractions resulted exclusively from a change in receptor number and was accompanied by a 4- to 6-fold decrease in the content of extractable insulin in these fractions; the latter observation suggests that receptor internalization, rather than receptor synthesis, is diminished. The effects of diazoxide on plasma insulin concentration, insulin binding to Golgi fractions, and insulin content of Golgi fractions were fully prevented by tolbutamide, a stimulant of insulin secretion. These results show that acute hypoinsulinemias in rats are accompanied by changes in the subcellular distribution of hepatic insulin receptors that are opposite to those previously observed in acute hyperinsulinemias. Furthermore, both in acute hyperinsulinemic and hypoinsulinemic models, a significant correlation is observed between plasma insulin concentration on the one hand, and insulin binding to Golgi fractions as well as insulin content of Golgi fractions on the other. It is concluded that the extent to which hepatic insulin receptors are internalized is a function of their occupancy by endogenous hormone, and that, at least under acute conditions, receptor internalization is one major mechanism involved in receptor regulation.

Animals↗
PubMed1987

[Systemic deficiency of carnitine].

Authors present a case of carnitine systemic deficiency. Relevant signs being severe muscular hypotonia, fat infiltration of the liver and muscles, as well as frequent episodes of severe hypoglycemia. Infrequent occurrence of this syndrome (this being the first case in our country) and therapeutic implications involved, justify this comment. Evolution is favourable if the correct treatment is applied.

Biopsy↗
PubMed1986

Conservation in rotaviruses of the protein region containing the two sites associated with trypsin enhancement of infectivity.

The primary structure of the region in the outer layer protein VP3, containing the two sites associated with trypsin enhancement of infectivity of rotavirus was found to be greatly conserved in cultivable human rotavirus serotypes 1 (Wa), 2 (DS1), and 3 (P) and in four human rotaviruses directly purified from feces. Significant differences with this conserved sequence were found in human rotavirus serotype 4 (ST3), isolated from an asymptomatic neonate, and in seven animal rotaviruses. However, the two trypsin cleavage sites were conserved in every rotavirus VP3 sequence analyzed.

Amino Acid Sequence↗
PubMed1986

Heterogeneity in base sequence among different DNA clones containing equivalent sequences of rotavirus double-stranded RNA.

The nucleotide sequences for several complementary DNA clones of the rotavirus genome were determined. When the sequences obtained from different clones for the same regions (16,000 bases) were compared, differences in eight base positions were observed. These discrepancies, approximately 1 in 2,000 bases, may be due to differences in individual RNA genomes resulting from multiple passages; infidelity of DNA synthesis in the cloning procedure; or both factors. Whatever the cause, this frequency of base substitution found in sequences of complementary DNA obtained from the same isolate should be considered when comparing DNA sequences obtained from independent isolates. On the other hand, the frequency of base changes observed suggests that the rotavirus genome is very conserved since the virus used for cDNA synthesis has been continuously passaged for 6 years without plaque purification.

Base Sequence↗
PubMed1986

How culture is considered in evaluations of psychopathology.

A mail survey was conducted to explore how mental health professionals take culture into account in their evaluations of psychopathology and to assess their reported attitudes toward the role of culture in their work. The respondents were 118 licensed social workers, psychologists, and psychiatrists from the state of California. Their reported attitudes and behavior represent a culturally sensitive position. For example, 83% of the sample indicated that they consider culture for most or all of their culturally different patients. A total of 96 therapists provided brief case summaries describing how they took culture into account for a given patient. A qualitative analysis revealed that culture is considered throughout the evaluation and treatment process. Furthermore, 35 case summaries referred to changes in the therapists' clinical evaluations as a result of considering culture. All but three of the case summaries indicated that clinicians judged the problems to be less severe or less pathological when thought to be cultural in nature. The risk of dismissing actual psychopathology as culturally normative behavior is considered.

Adolescent↗
PubMed1985

Primary structure of the cleavage site associated with trypsin enhancement of rotavirus SA11 infectivity.

The primary structure of the trypsin cleavage site in the outer layer protein VP3 of rotavirus SA11 was determined. This cleavage enhances the infectivity of rotavirus SA11. Both VP8, one of the polypeptides generated by the cleavage, and VP3 had their alpha-NH2 blocked. Only VP5, the other polypeptide produced by the cleavage, was susceptible to sequential Edman degradation, indicating that it contained the new alpha-NH2 terminus generated by trypsin hydrolysis. The results indicated that purified VP5 is composed of two polypeptides with the following amino acid sequence at their N terminus: (a) ??VYTRAQPNQDAVVSKTS...; (b) AQPNQDAVVSKTS.... Sequencing of the DNA complementary to ds RNA segment 4 revealed a nucleotide sequence encoding the amino acid sequences indicated above, with only one different amino acid. From these results, the amino acid sequence of the site cleaved by trypsin was extended to cover the C termini (present in VP8). The following sequence, which contains two sites (indicated with asterisks) and can be cleaved by trypsin was deduced: ... VPVSIVSR*NIVYTR*AQPNQDIVVSKTS....

Amino Acid Sequence↗
PubMed1984

Primary structure of the neutralization antigen of simian rotavirus SA11 as deduced from cDNA sequence.

DNA sequences complementary to the double-stranded RNA coding for the neutralization antigen (glycoprotein VP7) of simian rotavirus SA11 have been cloned. The VP7 gene consists of 1,062 nucleotides, containing an uninterrupted coding sequence of 978 nucleotides which specifies a glycoprotein of 326 amino acids. The significance of a second possible initiation site 30 nucleotides downstream from the first is discussed. Partial amino acid sequence of this glycoprotein showed unequivocally that the cloned segment (segment 9) codes for glycoprotein VP7 of SA11. The resulting amino acid sequence contained only one carbohydrate acceptor site. Possible sites of membrane interaction and antigenic determinants are discussed based on the analysis of the hydrophobicity and hydrophilicity profiles of VP7.

Amino Acid Sequence↗
PubMed1982

Calculation of half-lives of proteins in vivo. Heterogeneity in the rate of degradation of yeast proteins.

A method is given for the calculation of half-lives of proteins in vivo from the measurement of the decrease of radioactivity in pulse-labelled proteins with time. This method could be particularly useful for the study of the degradation of proteins in cells that have a low growth rate. The method applied to growing yeast indicates that there are two major classes of protein. The class with low turnover constitutes the bulk of yeast protein and has a half-life of 160 h in a medium with glucose or galactose and of 50 h in a medium with ethanol. The class of proteins with high turnover (half-life between 0.8 and 2.4 hours) represents from 1% of total protein in yeast growing on glucose to 7% in yeast growing on ethanol. It is shown that some proteins which are depressed during growth on ethanol or induced during growth on galactose are particularly susceptible to degradation in a medium which contains glucose. It is proposed that protein degradation is regulated by a coarse control at the level of protease activity and a fine control on the susceptibility of individual proteins to proteases.

Ethanol↗
PubMed1982

Gene protein products of SA11 simian rotavirus genome.

When MA104 cells were infected with SA11 rotavirus, 12 protein classes, absent in mock-infected cells, could be distinguished by polyacrylamide gel electrophoresis. At least two of these proteins were glycosylated, and their synthesis could be blocked with tunicamycin. The oligosaccharides of both glycoproteins were cleaved by endo-beta-N-acetylglucosaminidase H, suggesting that they were residues of the "high-mannose" type. Of the 12 viral polypeptides observed in infected cells, 1 was probably the apoprotein of one of these glycoproteins; 5, including 1 glycoprotein, were structural components of the virions, whereas the other 6, including a second and possibly third glycoprotein, were nonstructural viral proteins. When the 11 double-stranded RNA genome segments of SA11 were translated, after denaturation, in an RNA-dependent cell-free translation system, at least 11 different polypeptides were synthesized. Ten of these polypeptides had electrophoretic migration patterns equal to those of viral proteins observed in tunicamycin-treated infected cells. Nine of the 11 double-stranded RNA genome segments were resolved by polyacrylamide gel electrophoresis and were translated individually. Two were not resolved from each other and therefore were translated together. Correlation of each synthesized polypeptide with an individual RNA segment allowed us to make a probable gene-coding assignment for the different SA11 genome segments.

Glycoproteins↗
PubMed1982

[Male XX-syndrome].

Described in this paper is a patient, aged eleven years and eight months, with micropenis, dorsal prepuce, and rugous, partially bifid scrotum. FSH and LH values below normal were obtained from hormonal investigation. LH-RH stimulation was followed by retarded FSH response of moderate intensity, while the LH profile was moderately strong. Cytogenetic tests revealed the presence of 25 per cent of female sex chromatin. The karyotype was 46 XX. The patient did not have internal female genital organs, and his gonads were of testicular appearance. Histologically, both testicles exhibited tubules with primitive germinal cells and Sertoli cells. An inconspicuous number of Leydig cells was recorded from the interstitium.

Child↗
PubMed1981

Experimental antireflux intestinal valve.

A reflux-preventing valve was obtained by invaginating a 3.5 to 4.5 cm segment of small bowel into the distal lumen, after removing the seromuscular layers at both ends of the segment of bowel. Antiperistaltic pressure resistance, measured at regular intervals during 6 months, showed valves with competence equal or superior to the ileocecal valve. The blood supply to the intussuscepted segment must be carefully preserved.

Animals↗
PubMed1981

Structural polypeptides of simian rotavirus SA11 and the effect of trypsin.

Analysis of purified simian rotavirus has shown that it contains fewer structural polypeptide classes than previously reported. Two polypeptides (molecular weights, 62,000 and 28,000) commonly found in purified rotaviruses were, in fact, produced by cleavage of a larger structural polypeptide (molecular weight, about 88,000) by trypsin, which is usually employed to increase the yield of rotaviruses in tissue culture. Trypsin-uncleaved, double-shelled rotaviruses are probably composed of only five polypeptide classes; three in the inner layer, and two in the outer layer.

Electrophoresis, Polyacrylamide Gel↗