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Biomedical subjects

G Stein

Publications and source records attributed to G Stein.

At least 271 records · Page 15Linked to original sources
PubMed1986

Sequence and organization of genes encoding the human 27 kDa heat shock protein.

The 27 kDa human heat shock protein (hsp27) is encoded by a gene family of 4 members. Two genomic fragments hybridizing to cDNA encoding hsp27 have been isolated, characterized, and sequenced. One clone is a member of a cluster of three genes linked within a 14-18 kb region of the genome and encodes a transcript interrupted by two intervening sequences. A single open reading frame encodes a polypeptide of 22,300 deduced molecular weight. The 5' flanking region contains two transcription start sites and sequences homologous to the Drosophila consensus heat inducible control element. Induction of both potential transcripts follows heat shock in vivo. Accurate heat inducible transcription occurs at both start sites after injection into Xenopus oocytes. The second genomic clone is a processed pseudogene lacking promoter elements and is unlinked with the other members of the hsp27 gene family. The amino acid sequence of human hsp27 shows striking homology with mammalian alpha crystallin, and contains a region towards the carboxy terminus which shares homology with the small hsp of Drosophila and other organisms.

Amino Acid Sequence↗
PubMed1986

Renal effects of aluminium in uraemic rats and in rats with intact kidney function.

The effect on renal function following administration of aluminium (i.p., five times weekly (0.05 or 0.5 mg kg-1 body weight) for 12 weeks) to partially nephrectomized (5/6 NX) or intact female rats was examined. The observed loss of concentrating ability, characterized by increased urine volume and an increased sodium excretion, as well as increased renal excretion of p-aminohippurate (demonstrable after low-dose treatment with nephrotoxins) can be interpreted as an initiation of kidney function injury. No distinct differences in response were observed between partially nephrectomized and intact animals.

Aluminum↗
PubMed1986

Localization of human histone gene transcripts predominantly in the nonmatrix nuclear fraction.

Using S1 nuclease protection assays, we have examined the representation of cell cycle-dependent H4 histone RNAs in the nuclear matrix and nonmatrix nuclear fractions of human cells. Cytoplasmic and nuclear fractions were prepared from exponentially growing HeLa S3 cells by double detergent (sodium deoxycholate and NP40) lysis. The nuclear matrix and nonmatrix nuclear fractions were then prepared by digestion of nuclei with RNase-free DNase I and subsequent high-salt [0.4 M (NH4)2SO4] extraction. Subcellular fractions were characterized by 1) DNA, RNA, and protein composition; 2) electrophoretic analysis of the proteins in each fraction; 3) the representation of 45S ribosomal RNA precursors and processed 18S and 28S ribosomal RNAs; and 4) the presence of mitochondrial RNAs. In contrast to ribosomal and messenger RNA precursors, which are largely associated with the nuclear matrix, the human H4 histone RNAs in the nucleus were found predominantly in the nonmatrix nuclear fraction. The presence of H4 histone RNA in the nonmatrix nuclear fraction appeared to be coupled to DNA replication, since inhibition of DNA synthesis by hydroxyurea resulted in a loss of histone RNA from the nucleus. Our results suggest either that the association of histone RNAs with the nuclear matrix is very transient or that posttranscriptional modifications of the rapidly processed histone gene transcripts do not involve the nuclear matrix.

Cell Cycle↗
PubMed1986

Human histone gene organization. Identification of a histone gene polymorphism prevalent in a black population.

Analysis of the restriction enzyme digests of total genomic DNAs from a broad spectrum of human cell lines and from individuals with different genetic backgrounds, by hybridization with a series of cloned human histone sequences, indicated restriction site polymorphisms (RSPs) for two adjacent human histone genes which reside on chromosome 1. In most cell lines and individuals examined we observed a single 2.05 kb H4 histone HindIII fragment and a 7.0 kb H3 histone HindIII fragment. In contrast, the polymorphisms were manifested as a 2.15 kb H4 HindIII fragment and a 9.1 kb H3 HindIII fragment. From population studies, we were able to show that there is no linkage disequilibrium between these two polymorphic restriction sites. Nor was there any apparent correlation between the presence of the H3/H4 histone polymorphisms and maintenance of the transformed karyotype, passage in culture, transformation or tumor progression. These chromosome 1 H3 and H4 histone gene polymorphisms are common in the American Black population and, in our survey of individuals, were not found in the American Caucasian population. Among the American Blacks studied, the frequency of the H3 HindIII(-) allele is 43% and of the H4 HindIII(-) allele 30%. In limited family studies, we were unable to detect recombination between these two physically linked alleles.

Black People↗
PubMed1986

Involvement of the 5'-leader sequence in coupling the stability of a human H3 histone mRNA with DNA replication.

Two lines of evidence derived from fusion gene constructs indicate that sequences residing in the 5'-nontranslated region of a cell cycle-dependent human H3 histone mRNA are involved in the selective destabilization that occurs when DNA synthesis is terminated. The experimental approach was to construct chimeric genes in which fragments of the mRNA coding regions of the H3 histone gene were fused with fragments of genes not expressed in a cell cycle-dependent manner. After transfection in HeLa S3 cells with the recombinant plasmids, levels of fusion mRNAs were determined by S1 nuclease analysis prior to and following DNA synthesis inhibition. When the first 20 nucleotides of an H3 histone mRNA leader were replaced with 89 nucleotides of the leader from a Drosophila heat-shock (hsp70) mRNA, the fusion transcript remained stable during inhibition of DNA synthesis, in contrast to the rapid destabilization of the endogenous histone mRNA in these cells. In a reciprocal experiment, a histone-globin fusion gene was constructed that produced a transcript with the initial 20 nucleotides of the H3 histone mRNA substituted for the human beta-globin mRNA leader. In HeLa cells treated with inhibitors of DNA synthesis and/or protein synthesis, cellular levels of this histone-globin fusion mRNA appeared to be regulated in a manner similar to endogenous histone mRNA levels. These results suggest that the first 20 nucleotides of the leader are sufficient to couple histone mRNA stability with DNA replication.

Animals↗
PubMed1986

Cell cycle-dependent expression of a stable episomal human histone gene in a mouse cell.

We have constructed a recombinant plasmid that includes a cell cycle-dependent human H4 histone gene with 650 base pairs of 5' and 900 base pairs of 3' flanking sequences and the 69% transforming fragment of bovine papilloma virus. When transfected into C127 mouse cells, this plasmid is maintained as a stable episome with approximately 20 copies per cell. Micrococcal nuclease digestion indicates that the episomal human histone gene is packaged as chromatin. The human H4 histone transcript is initiated at the correct 5' start site and undergoes selective destabilization when DNA synthesis is inhibited. When C127 cells containing the episomal H4 histone gene are synchronized, the human H4 histone mRNA levels are regulated coordinately with DNA replication and parallel those of transcripts from the murine chromosomal H4 histone genes. Our results suggest that the regulatory sequences and/or regulatory molecules associated with murine and human histone genes are compatible. The human histone gene-bovine papillomavirus episome is therefore a viable system for studying cell cycle-regulated histone gene expression under conditions where control is not influenced at the site of chromosomal integration by cis-acting elements of genes normally not contiguous.

Animals↗
PubMed1986

Enhancer-facilitated expression of prokaryotic and eukaryotic genes using human histone gene 5' regulatory sequences.

We examined the structural and functional properties of a human H3 histone gene promoter. The complete nucleotide sequence of an H3 structural gene and 515 nucleotides of 5' and 100 nucleotides of 3' flanking sequences were determined. The upstream region of this cell cycle dependent H3 histone gene, designated pST519, contains consensus sequences typical of genes transcribed by RNA polymerase II. To address promoter function directly, we determined the capability of the 5' flanking sequences to direct the transcription of two genes which are not functionally or structurally related. Fusion genes were constructed using the 5' flanking sequences of this human H3 histone gene and either human beta-globin or bacterial chloramphenicol acetyltransferase (CAT) coding sequences. Both of these fusion genes were expressed when transfected into HeLa cells. Under control of the pST519 histone gene promoter, a beta-globin mRNA transcript was initiated at the appropriate H3 (bp) enhancer, inserted upstream from the histone promoter in both fusion constructs, increased levels of beta-globin and CAT expression. Expression of the pST519 H3 histone gene in COS cells in the absence of the SV40 72-bp enhancer confirmed that the sequences required for promoting transcription reside within the 750-bp 5' flanking sequences and that the exogenous enhancer facilitates, but is not a prerequisite for, transcription. Enhancer-facilitated expression of a cell cycle dependent human H4 histone gene was also observed following transfection into mouse L cells and indicates that the regulatory sequences of human histone genes and transcription factors of mouse cells are compatible.

Acetyltransferases↗
PubMed1986

[Comparative studies of calcium resorption modified by vitamin D2 and D3 in patients with chronic renal failure and dialysis patients].

In 16 patients with a chronic renal insufficiency at the stage of the compensated retention and 13 test persons of the chronic haemodialysis programme determinations of the total calcium and of the ionized calcium fraction as well as investigation of the intestinal calcium absorption by means of the isotope 47Ca were performed. In these cases the influence of vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) on these parameters of the calcium metabolism was compared. Under the treatment with vitamin D a normalization of the serum calcium levels concerning the total calcium concentration as well as with regard to the ionized calcium fraction was achieved; this effect took place parallel to the improvement of the intestinal calcium absorption. Vitamin D3, had a more favourable effect than vitamin D2. The necessary doses are below 40,000 U a day.

Blood Urea Nitrogen↗
PubMed1986

No tissue level abnormality of vitamin A concentration despite elevated serum vitamin A of uremic patients.

In 57 patients with chronic renal failure (CRF) [44 patients on regular dialysis treatment (RDT), 33 renal transplant patients (RT) and 26 normal patients (NP)] and in a further 11 patients with CRF (8 patients on RDT and 17 patients without any renal disease in the post mortem) the vitamin A content of the serum obtained from the tissue of the liver, the stomach, the subcutaneous adipose tissue and the bone were analyzed. The vitamin A content of the serum was increased significantly for all groups of patients in comparison with the control group, but hypervitaminotic ranges were not reached in any case. The vitamin A content decreased depending on the time of dialysis treatment and the period after kidney transplantation. The retinol-binding protein accumulated even more than vitamin A in CRF and RDT. This statement is not in conformity with that of a hypervitaminosis A, of which normal respectively decreased RBP levels are characteristic. The serum prealbumin concentration was near the upper limit of the normal range in all groups of patients. The serum content of beta-carotene in patients with CRF and RDT was raised in comparison with NP and RT patients. As to the vitamin A content of the organs, a distinctive decrease appeared in the liver, so that a marginal supply must be assumed. In the stomach and the subcutaneous adipose tissue no changes, in comparison with the control patients, resulted. Due to renal insufficiency the results indicated an unphysiological situation in the vitamin A metabolism. Connections with disturbances of the fat-household could not be set up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

[Morphometric and histochemical studies of the skeletal muscles of patients with chronic renal failure and dialysis patients].

In 19 patients with chronic renal insufficiency in the stage of compensated retention, 20 patients undergoing dialysis and 24 patients with normal renal function muscle tissue was taken by an open biopsy and investigated histologically, histochemically as well as morphometrically. A neurogenic atrophy stood in the foreground of the histologic changes of the striated musculature in uraemia, a pure type II atrophy was found more infrequently. In the patients undergoing dialysis frequency and size of these disturbances were more distinct. Except for a possible influence of a disturbed calcium metabolism other pathogenetic factors supposed in literature could not be found.

Adult↗
PubMed1986

[Desferal treatment of aluminum poisoning; effect on serum concentrations of aluminum (Al), iron (Fe) and copper (Cu)].

In 2 patients with a progressive dialysis encephalopathy and increased serum aluminium concentrations a Desferal-treatment with 500 mg per week was performed and in these cases the kinetics of Al, Fe, Cu was investigated. After the application of Desferal an increase of the serum levels, the ultrafiltrable proportion, the dialysance and the eliminated quantity of aluminium developed. In the course of the treatment in the two patients the aluminium level could be reduced to approximately normal values. Nevertheless one patient died of a severe course of a progressive dialysis encephalopathy. An increase of the copper concentration independent of Desferal-treatment after the dialysator passage remained without influence on the course of concentration of the serum copper in the examination period. A remarkable effect of the Desferal-therapy on the iron metabolism could not be established. Since in the dosage used there did not appear any side effects the Desferal-application is to characterized as a distinct and effective technique for the decrease of the serum-aluminium-concentration in patients undergoing dialysis.

Adult↗
PubMed1986

[Histochemical localization of aluminum deposits in bones and their relation to the clinical and histomorphometric findings in patients with chronic renal failure].

In 60 patients with chronic renal insufficiency and 36 dialysis patients an iliac crest biopsy was performed, on the undecalcified bone morphometric determinations were carried out as well as the aluminium deposition was investigated histochemically. Histologically were found in 3 patients normal findings, in 11 patients a fibroosteoclasia, in 23 patients an osteoidosis and in 59 patients a combination fibroosteoclasia and osteoidosis. 3 oft the 60 patients with a chronic renal insufficiency had aluminium depositions in the polyblasts. Of the 36 dialysis patients 19 (55.4%) had a positive aluminium histology: 30.7% of the patients with osteoidosis and 23.7% with a mixed form. There was a positive correlation to the bone and osteoid volume, to the osteoid surface and a negative relation to the activity of osteoblasts, the absorption surface and the activity of osteoclasts. Aluminium depositions on the mineralisation border might be of importance for the changes.

Adolescent↗
PubMed1985

Coordinate regulation of histone mRNAs during growth and differentiation of rat myoblasts.

To determine whether histone genes are coordinately regulated, histone mRNA concentrations were measured in exponentially growing L6 myoblasts, S-phase synchronized myoblasts and in differentiating myoblasts. The levels of various histone mRNA subspecies declined rapidly and coordinately once myoblasts were given the signal to differentiate. mRNA levels were reduced on average to 1-5% of the amount observed in exponentially growing cells by 48 h after the signal to differentiate. The reductions occurred in concert with the cessation of DNA synthesis as the cells differentiated. Inhibition of DNA synthesis by treating myoblasts with Ara-C or hydroxyurea resulted in a histone mRNA half-life of 10-13 min for each of the histones examined. One example of non-coordinate regulation was observed however among the H4 mRNA subspecies in S-phase synchronized cells. The levels of two major subspecies of H4 mRNA increased coordinately in S-phase compared to levels observed in cells growing exponentially. A third subspecies of H4 mRNA on the other hand was found to decline by 50%. These studies suggest that the majority of histone mRNA subspecies are under coordinate control, although one exception has been noted among the subspecies of histone H4.

Animals↗
PubMed1985

Enhancer-facilitated expression of a human H4 histone gene.

Cultured mammalian cells were transfected with a recombinant human H4 histone gene. S1 nuclease mapping of cellular RNAs from transfected cells revealed: (i) correct initiation of transcription at the cap site, with some transcripts originating from other sites in the 5' flanking region of this H4 gene; (ii) cis-linkage of an SV-40 transcriptional enhancer element upstream of the H4 5'-flanking region resulted in about a 50-fold increase in the level of correctly initiated H4 mRNA and (iii) in a heterologous murine system stability of human H4 mRNAs was apparently sensitive to inhibition of DNA-synthesis by hydroxyurea. Our results suggest that certain sequences required for the initiation of a human H4 histone gene transcript reside within the 210 nucleotides immediately upstream from the cap site and that the level of expression is influenced by the introduction of an enhancer element.

Animals↗
PubMed1985

Subcellular localization of histone messenger RNAs on cytoskeleton-associated free polysomes in HeLa S3 cells.

We have examined the subcellular distribution of histone mRNA-containing polysomes in HeLa S3 cells to assess the possible relationship between localization of histone mRNAs and the regulation of cellular histone mRNA levels. The distribution of histone mRNAs on free and membrane bound polysomes was examined as well as the association of histone mRNA-containing polysomes with the cytoskeleton. The subcellular localization of histone mRNAs was compared with that of HLA-B7 mRNAs which encode a cell surface antigen. Histone mRNAs were localized predominantly on the free polysomes, whereas the HLA-B7 mRNA was found almost exclusively on membrane bound polysomes. However, both species of mRNA were found associated with the cytoskeleton. Interruption of DNA synthesis by hydroxyurea treatment resulted in a rapid and selective destabilization of histone mRNAs in each subcellular fraction; in contrast, the stability of HLA-B7 mRNA appeared unaffected. The results presented confirm that histone mRNAs are predominantly located on non-membrane bound polysomes and suggest that these polysomes are associated with the cytoskeletal framework.

Cycloheximide↗
PubMed1985

Two-pool model analysis of data in hemodialysis by means of programmable pocket calculator TI 59.

Four parameters of a two-pool model are evaluated by an iterative method using the explicit solutions of the linear differential equations. For this it was presumed that the residual renal clearance is sufficiently small. Five data pairs of measured plasma concentrations ci for the time points ti (i = 0 to 4), as well as the dialyzer and residual renal clearances (KD and KR), must be given and put in the calculator. A sample run is shown for urea kinetics. The parameter estimation takes about 10 min. The program is suitable to assist in the individualization of dialysis therapy.

Computers↗
PubMed1985

[Bone changes in Hansen's disease].

Bone lesion is a frequent organic manifestation in leprosy. Osseal destructions caused by granulomatous process induced by M. leprae are so-called specific lesions in contrast to non-specific lesions based on nerval or arterial diseases. The specific osseal alterations are characterized by cystic brightenings in roentgenograms while non-specific osseal changes show absorption to bone structure as akroosterolysis and osteoporosis. Typical radiologic findings in different stages of mutilation are demonstrated.

Bone Diseases↗