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Biomedical subjects

A Gal

Publications and source records attributed to A Gal.

At least 253 records · Page 14Linked to original sources
PubMed1984

Genetic analysis of dexamethasone resistance in L cells by somatic cell hybridization.

Stable dexamethasone resistant and receptor-containing (R+) variants of L cells have been characterized by somatic cell hybridization. Neither of the variants had a clearly dominant phenotype in hybrids with dexamethasone-sensitive fibroblast lines, i.e. the resistance of the variants was not due to transdominant factors. Somatic cell hybrids formed between one of the R+-resistant clones and an independent resistant fibroblast cell line showed complementation--the hybrid clones were as sensitive to the steroid as the sensitive parental lines. Complementation, however, disappeared after continued culture of the clones. The return of the dexamethasone-sensitive phenotype was not always linked with similar changes in the responsiveness to another steroid, e.g. progesterone. Our clones can be considered to be resistant variants, designated death-less (d-), where the cells are defective in a non-receptor component involved in the hormone response. The fact that complementation can occur indicates the existence of at least two such steps in the pathway.

Animals↗
PubMed1984

Differential DNase I sensitivity of the albumin and alpha-fetoprotein genes in chromatin from rat tissues and cell lines.

We have examined the DNase I sensitivity of the albumin and alpha-fetoprotein (AFP) genes in different rat tissues (adult liver and kidney) and cloned cell lines (hepatoma 7777-C8, JF1 fibroblasts), which show drastic differences in the level of expression of these two genes. This was done by studying the disappearance of defined restriction endonuclease fragments of these genes as a function of limited DNase I digestion. The sensitivity of these genes was compared to that of a gene not expressed in the hepatic cells and to that of a ubiquitously expressed gene. In nuclei from adult rat liver the albumin and AFP genes were preferentially degraded by the nucleolytic action of DNase I, whereas they were not in rat kidney nuclei. In the hepatoma cells the AFP gene was much more sensitive to DNase I digestion than the albumin gene; both genes were very resistant to DNase I action in fibroblastic nuclei. When analyzed in relation to the level of gene expression our results indicate that alterations in the chromatin structure of the albumin and AFP genes might be involved in the early establishment of the tissue-specific potential of overt gene expression; such alterations reflected in an altered DNase I sensitivity do not appear to be responsible for the changes in gene activity occurring during the terminal differentiation of the hepatocyte; and modifications in the chromatin structure of these genes might occur during oncogenic events; these structural modifications could be related to the changes in gene expression observed in hepatocarcinogenic processes.

Animals↗
PubMed1984

Ocular findings in the acquired immunodeficiency syndrome.

A patient with acquired immunodeficiency syndrome is described. Both retinae were severely affected. Vision was reduced to light perception with projection incerta in the right eye and finger counting at 1.5 m in the left eye. Eye involvement is common in this syndrome, appearing at an early stage of the disease. The fundal appearance could thus be of help in diagnosis.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Protease activity in fibromyoma and normal human myometrium.

The potential involvement of intracellular proteases in the pathophysiology of fibromyoma was studied by assay of activity of two proteolytic enzymes in fibromyoma and adjacent normal myometrium. Protease I, a soluble acid protease and protease II, a particulate protease optimally active at the neutral pH range are present in fibromyoma as well as in normal myometrial tissue. No consistent difference was observed between the specific activities of these enzymes in the fibromyoma and the surrounding myometrium. The large variation in the specific activity of the protease noted among normal and fibroid tissue samples from different patients cannot be ascribed to differences in cellularity. This variance might suggest differences in rate of processing of steroid hormones or different degrees of vascularization. The present findings do not support a major role for modulation of intracellular protease activities in the development of fibromyoma.

Adult↗
PubMed1983

Reconstitution of a functional beta-adrenergic receptor using cholate and a novel method for its functional assay.

Solubilization of purified turkey erythrocyte membranes at increasing cholate to protein ratios and in the presence of salt, extracts up to 20% of the beta-adrenergic receptor together with the GTP stimulatory protein (Ns) of adenylate cyclase. Upon removal of the cholate, by active absorption on Bio-beads, the functional interaction between the beta-receptor and the GTP regulatory protein Ns is quantitatively restored. The receptor (R) in the presence of l-isoproterenol and p[NH]ppG is able to catalyze the activation of Ns to its permanently active state, N's p[NH]ppG, with a rate constant (kon) identical to that of the native membrane. Reconstitution of the R/Ns mixture using poly(ethyleneglycol)-6000 restores the receptor binding properties as effectively as SM-2 Bio-beads. Unlike SM-2 Bio-beads, however, poly(ethyleneglycol) is not as efficient in restoring the R to Ns functional coupling. In this communication we also report on the ability to monitor quantitatively N's . p[NH]ppG, using native turkey erythrocyte membranes in the presence of Lubrol-PX as the source of the catalytic unit (c) of adenylate cyclase. The latter method is as efficient as using S49 AC- lymphoma cell membranes but much less expensive. Using this technique, we also demonstrate that when the Ns to C interaction is nullified, employing treatment with N-ethylmaleimide, the parameters which characterize R to Ns coupling remain unchanged.

Adenylyl Cyclases↗
PubMed1983

Detection of rare mRNA species in a complex RNA population by blot hybridization techniques: a comparative survey.

The detection of very rare mRNA species in a complex RNA preparation by current RNA blotting techniques is not straightforward. To be able to determine the size of mRNA molecules representing 10(-6) to 10(-7) of the total mass of an RNA preparation, a quantitative comparison of the level of detection of denatured mRNA species electrophoretically separated on agarose gels, followed by transfer to either nitrocellulose or diazobenzyloxymethyl (DBM) paper and hybridization to specific cDNA probes was carried out. Different transfer procedures were analyzed. Optimal conditions have been found which allowed the detection of RNA bands containing as little as 5 pg of a specific sequence within a few days of autoradiography following hybridization with highly labeled [32P]cDNA probes. Using this procedure it was shown that the low amounts of alpha-fetoprotein (AFP) mRNA sequences present in adult rat liver are mature AFP mRNA molecules.

Animals↗
PubMed1983

Altered protein glycosylation and procollagen to collagen conversion in human fibroblasts.

Skin fibroblasts, from a 9-year-old girl with an apparent heritable disorder of connective tissue, were cultured in vitro. The biosynthesis of the extracellular matrix glycoproteins, procollagens, and fibronectin was studied using radioactively labeled sugars and amino acids. Glycoproteins synthesized and secreted into the growth medium were found to be only partially glycosylated and the extracellular limited proteolytic conversion of procollagen type I to collagen was impaired, with procollagen chains accumulating in the growth medium. These biosynthetic alterations have not been previously reported in human skin fibroblasts, but similar findings have been described in tunicamycin-treated chick fibroblasts.

Biological Transport↗
PubMed1982

No evidence for post-transcriptional control of albumin and alpha-fetoprotein gene expression in developing rat liver neoplasia.

Rot analysis of hybridization data using highly labeled alpha-fetoprotein (AFP) and albumin (32P)cDNA probes has been used to quantitate AFP and albumin mRNA sequences in RNA preparations from different subcellular fractions of developing rat liver and Morris hepatoma 7777. In addition, size analysis of these mRNA sequences has been carried out by electrophoretic fractionation on agarose gels containing methylmercury hydroxyde and hybridization to radioactive cloned albumin and AFP cDNA probes. In all the tissues examined (fetal, newborn and adult rat liver, and hepatoma 7777) most of the albumin and AFP mRNA sequences were found associated with the polysomes as mature mRNA molecules; less than 2% of these sequences were present in the nuclear or the non polysomal cytoplasmic compartments. The number of AFP mRNA molecules was found to decrease in parallel in all the cellular compartments during rat liver development. In Morris hepatoma 7777 the content of albumin mRNA was considerably decreased in all the cellular fractions as compared to normal liver. These results demonstrate that post-transcriptional control mechanisms leading to an accumulation of non-functional mRNA molecules are not implicated in the changes of expression of albumin and AFP genes during rat liver development and neoplasia.

Animals↗
PubMed1982

Eco RI restriction-site polymorphism of the albumin gene in different inbred strains of rat.

Two types of variant EcoRI restriction enzyme patterns of albumin-gene DNA fragments have been detected in different rat strains by agarose gel electrophoresis and Southern blot hybridization using 32P-labeled cloned rat albumin cDNA probes. The type I albumin gene variant is characteristic of the Sprague-Dawley strain, and type II is found in Buffalo rats. The occurrence of these variants is interpreted as the result of simple allelic polymorphism because they are inherited in a normal Mendelian fashion when crossing Sprague-Dawley and Buffalo rats. The distribution of the two genetic variants in various inbred strains of rat suggests that type I represents the original or ancestral form of the albumin gene and that type II appeared spontaneously during laboratory breeding.

Animals↗
PubMed1980

Poly(A)- and nonpoly(A)-RNA associated with rat brain microsomal fractions: in vivo labelling studies.

The time course of incorporation of radiolabelled precursor into RNA associated with rat brain free polyribosomes, rough membranes, and smooth membranes was measured following a single intracranial injection of [3H] orotic acid. Polyadenylated RNAs were separated from nonpolyadenylated RNAs by affinity chromatography on oligo (dT)-cellulose columns. Poly(A)-RNA associated with each of the microsomal fractions became more rapidly labelled than did the nonpoly(A)-RNA of the same fractions. While the labelling profiles of the nonpoly(A)-RNA isolated from the polyribosomes and rough membranes are similar from one fraction to another, the specific radioactivity of the poly(A)-RNA isolated from free polyribosomes increased much more drastically than that of the poly(A)-RNA associated with rough membranes. The labelling profiles of RNA species isolated from smooth membranes were very different in this respect from the two ribosomal fractions. There was a lag of more than four hours before significant label appeared in the RNA associated with the smooth membrane fraction. These studies demonstrate that the different populations of brain microsomal RNA are labelled at different rates, perhaps reflecting differences in the turnover of these RNAs and differences in their function.

Animals↗
PubMed1979

Piloplex, a new long-acting pilocarpine polymer salt. A: Long-term study.

Thirty eyes of 15 patients with open-angle glaucoma were followed up for a period of up to 1 year while being treated with Piloplex eye drops containg a new long-acting pilocarpine polymer salt. Average morning intraocular pressure (IOP) values during treatment with pilocarpine hydrochloride administered 4 times daily was 20.5 mmHg. Average morning IOP values during Piloplex medication administered only twice daily were 19.8 to 18.2 mmHg (range of averages on 14 sessions). These findings indicate the lower average pressure during Piloplex medication and show its prolonged hypotensive effect. Both medications contained an equivalent total daily amount of pilocarpine. Throughout the 1-year study period no adverse side effects were reported, and only 1 patient complained of local sensitivity reaction. Visual disturbances characteristic of pilocarpine eye drops were reduced from 3 times a day on pilocarpine hydrochloride 4 times daily to once a day on Piloplex twice daily.

Aged↗
PubMed1979

A clinical trial with Piloplex--a new long-acting pilocarpine compound: preliminary report.

A clinical comparison of the effect of Piloplex (an emulsion containing a new pilocarpine polymer compound) to that of pilocarpine hydrochloride 2% q.i.d.hloride on the intraocular pressure (IOP) was performed on 93 eyes of 51 open-angle glaucoma cases. Clinical studies showed that Piloplex produced a prolonged therapeutic effect, this being consistent with the slow release pattern it has displayed during in vitro experiments. Comparison of diurnal IOP measurements of 84 eyes have shown that when treated with Piloplex, 11 b.i.d., 58 eyes (69%) were under control (IOP values less than 20 mm Hg), whereas only 34 of these 84 eyes (40.5%) were under control when treated with pilocarpine hydrochloride 2% q.i.d. The overall mean diurnal IOP value of the 84 eyes during the treatment with Piloplex, 11 b.i.d., was lower by 2.89 mm Hg (P less than 0.005) than the overall mean diurnal IOP of the same eyes while treated with pilocarpine hydrochloride 2% q.i.d.

Adult↗
PubMed1978

Isolation and characterization of L-cell variants with altered sensitivity to glucocorticoids.

Stable glucocorticoid-resistant receptor-containing (R+) variants of L cells have been obtained and characterized. Five clones of such cells were obtained after chemical mutagenesis of the A9HT cell line. These clones and an additional, spontaneously resistant subclone of the LB82 cell line all contain glucocorticoid receptors which appear normal with regard to quantity, affinity for steroids, and in vivo localization in subcellular compartments. Somatic cell hybrids were formed between two of these R+-resistant clones, a previously isolated R-resistant clone, and three different sensitive L cell parents. In no case was steroid resistance dominant. Thus, these resistant L cells appear to be candidates for complementation analysis. The R+-resistant clones may be hindered in as yet undefined steps of glucocorticoid action.

Cell Division↗
PubMed1977

Properties of phenylalanine transfer ribonucleic acid with modified 3'-terminal end in protein biosynthesis using a rabbit reticulocyte cell-free system: effect of the replacement of cytidine residues from the CpCpA end of tRNA by 5-iodocytidine or 2-thiocytidine.

Phe-tRNA Phe from yeast containing 2-thiocytidine or 5-iodocytidine in position 75 of the polynucleotide chain or Phe-tRNA Phe in which both positions 74 and 75 were substituted by 5-iodocytidine were investigated in the poly U-dependent polyphenylalanine synthesis on ribosomes from rabbit reticulocytes. Phe-tRNA Phe-Cps2CpA was nearly as active as the native Phe-tRNA Phe-CpCpA in the overall process. Phe-tRNA Phe-Cpi 5CpA as well as Phe-tRNA Phe-i5Cpi 5CpA were considerably less active than the native species. Investigation of individual steps of protein biosynthesis with these modified substrates revealed that the donor activity of peptidyl-tRNAs which contain 5-iodocytidine in their 3'-terminus is strongly imparied suggesting exacting structural requirements for the interaction of the CpCpA end of tRNA with the ribosomal P-site.

Animals↗