Search PubMed⌕ Search

Biomedical subjects

G Stein

Publications and source records attributed to G Stein.

At least 289 records · Page 16Linked to original sources
PubMed1985

A unique subspecies of histone H4 mRNA from rat myoblasts contains poly(A).

Fractionation of rat L6 myoblast histone H4 mRNA into its three component subspecies revealed that one of the major subspecies (H4-1) contained poly(A). The unique poly(A)+ H4 mRNA makes up about 8% of the total polysomal H4 mRNA population detected. Unlike the poly(A)- histone mRNAs, whose levels are reduced by greater than 95% when myoblasts differentiate into myotubes, the poly(A)+ subspecies is reduced by only 70%. The poly(A)+ H4 mRNA from myotubes incubated with actinomycin D decays with a half-life of 37-42 min, which is similar to that obtained for the poly(A)- H4 mRNAs in myoblasts. Both the poly(A)+ and poly(A)- subspecies decay at an increased rate after inhibition of DNA synthesis. In myoblasts the poly(A)+ H4 mRNA exists almost exclusively in the polysomal compartment (greater than 95%) with little (less than 5%) in the free ribonucleoprotein (mRNA-protein or mRNP) complex compartment of the cell. Poly(A)- histone H4 mRNA subspecies, on the other hand, are distributed with approximately 80% in the polysomal compartment and 20% in the free mRNP complex compartment. The unique poly(A)+ H4 mRNA is unusual, not only in that it contains poly(A) but also in its behavior compared to poly(A)- H4 mRNAs during terminal differentiation.

Animals↗
PubMed1985

A human histone H4 gene exhibits cell cycle-dependent changes in chromatin structure that correlate with its expression.

By use of synchronized human HeLa S3 cells, a site sensitive to both DNase I and nuclease S1 was identified 50-150 base pairs upstream of the ATG codon of a cell cycle-dependent histone H4 gene. This site expanded to include a broad region of approximately equal to 300 base pairs sensitive to DNase I throughout S phase and then narrowed again to the original site after the completion of DNA replication. The level of nuclease S1 sensitivity was greatest during early S phase, when the gene is replicated and its transcription rate is maximal. The chromatin structure of the human beta-globin gene, which is not expressed in HeLa cells, was also analyzed throughout the cell cycle, and in no case was a sub-band seen as a result of DNase I or nuclease S1 digestion, nor were there any changes in nuclease sensitivity correlated with its replication. Thus the cell cycle-dependent chromatin alterations in this histone H4 gene appear to be due to the coupled replication and expression of this gene rather than simply its replication. These results suggest that histone genes, as compared with developmentally regulated genes, exhibit an "intermediate" level of regulation whereby the gene is never in a completely inactive conformation, but changes in chromatin structure occur as a function of the cell cycle and expression.

Base Sequence↗
PubMed1985

Vitamin levels in chronic renal failure and need for supplementation.

Deficiencies of water-soluble vitamins may occur in uremic patients mainly because of restricted consumption and of loss during chronic hemo- and peritoneal dialysis. Although the daily requirement for most vitamins is not well defined in chronic renal failure supplementation of the vitamins thiamine, riboflavin, pyridoxine, pantothenic acid, niacin and ascorbic acid, the form of one multivitamin preparation without vitamin A as well as folic acid in dialysis patients after each dialysis is recommended. There is no need for vitamin B12, vitamin A and vitamin E.

Ascorbic Acid↗
PubMed1985

[Osteitis leprosa multiplex cystica--an early symptom of lepromatous leprosy].

Bone lesions of the finger in a 20-year-old leprosy patient are described to show their diagnostic value. The aetiological differences between specific (caused by Mycobacterium leprae itself) and unspecific osseal changes are morphologically noticeable in morbus Hansen. The X-ray picture shows cystic lightening by granulomatous destruction and distal absorption of the bone. These lesions are typical, and radiological investigations might be the first step in the diagnosis of leprosy. In our case, ostitis leprosa multiplex cystica, an early, specific bone lesion, was predominant.

Adult↗
PubMed1985

[Vitamin A status of patients with chronic renal failure in relation to renal osteodystrophy].

In patients with chronic renal insufficiency and dialysis patients as well as in normal persons determinations of vitamin A in the serum and in the bone were performed and related to the parameters of the bone metabolism and to the histomorphometric investigation of the bone. The vitamin A serum levels were significantly increased in the two groups of patients, however, did not show any differences between the patients with an osteoidosis or the combination of osteoidosis and fibroosteoclasia. There were no correlations to calcium, phosphorus, PTH and to the alkaline phosphatase as well as to the individual histomorphometric data. The vitamin A content of the bone was low and did not show any differences to the normal persons. On the other hand, there were significant relations between the parathormone and the parameters of the regeneration and the absorption of the bones. An additional influence of vitamin A on the bone disturbance, eventually by the activation of the osteoclasts cannot be excluded.

Adult↗
PubMed1985

[Massive corpus luteum hemorrhage in a dialysis patient].

A 17-year old patient who was continuously dialyzed due to Fanconi-anemia and bilateral renal insufficiency developed an acute and severe bleeding from a ruptured Graafian follicle (corpus luteum). The bleeding was life-threatening, most likely due to the continuous treatment with heparin necessary for hemodialysis procedure. Differential-diagnostic considerations and interdisciplinary therapeutic measurements are reported.

Adolescent↗
PubMed1985

[Elimination of caffeine and metamizol in in vivo characterization of cytochrome P-450 dependent biotransformation reactions in aged humans].

Elimination of caffeine from plasma and excretion of main metabolites of metamizol (noramidopyrine methanesulphonate sodium) in urine were determined in young healthy (age 18-27 years) and in old aged volunteers (older than 65 years). From the elimination velocity of these model substances conclusions concerning the activity of 3-methylcholanthrene inducible (caffeine elimination) and of phenobarbital inducible (metamizol elimination) isoenzymes of cytochrome P-450 are drawn. Whereas in old age caffeine metabolism is unchanged, there is a strong delay in renal excretion of main metabolites of metamizol in old volunteers. It is concluded that different hepatic cytochrome P-450 isoenzymes are differentially influenced with increasing age in men.

Aged↗
PubMed1985

[The influence of chronic renal insufficiency on the demethylating activities of various cytochrome P-450 subspecies in humans].

Caffeine is mainly metabolized by 3-methylcholanthrene-inducible cytochrome P-450 (P-450MC) and metamizol (noramidopyrine methanesulfonate sodium) is mainly metabolized by phenobarbital-inducible cytochrome P-450 (P-450PB). That's why the half life of caffeine and the elimination of the main metabolites of metamizol were used as parameters in vivo characterizing both groups of the cytochrome P-450-complex. The influence of chronic renal insufficiency was investigated (8 patients in the stage of compensated retention, creatinine in serum 380-1280 mumol X l-1, and 6 hemodialyzed patients, here only metamizol elimination was established). Both the caffeine and the metamizol eliminations of patients with chronic renal insufficiency are not different from those of healthy volunteers. We concluded that the demethylation activity of the cytochrome P-450-complex is not distinctly influenced by chronic renal insufficiency.

Ampyrone↗
PubMed1984

A major human histone gene cluster on the long arm of chromosome 1.

A human histone gene cluster was assigned to chromosome 1 by Southern blot analysis of DNA's from a series of mouse-human somatic cell hybrids with 32P-labeled cloned human H4 and H3 histone DNA as probes. Localization of this histone gene cluster on the long arm of chromosome 1 was confirmed by in situ hybridization of this DNA probe to metaphase chromosomes.

Animals↗
PubMed1984

Expression of histone genes in a G1-specific temperature-sensitive mutant of the cell cycle.

The expression of genes coding for the four core histones (H2A, H2B, H3, and H4) was studied in tsAF8 cells. These baby hamster kidney-derived cells are a temperature-sensitive (ts) mutant of the cell cycle that arrest in G1 at the restrictive temperature. When serum-deprived tsAF8 cells are stimulated with serum, they enter the S phase at the permissive temperature of 34 degrees C, but are blocked in G1 at the nonpermissive temperature of 39.6 degrees C. Northern blot analysis using cloned human histone DNA probes detected only very low levels of histone RNA either in quiescent tsAF8 cells or in cells serum stimulated at the nonpermissive temperature for 24 h. Cellular levels of histone RNA were markedly increased in cells serum stimulated at 34 degrees C for 24 h. Temperature shift-up experiments after serum stimulation of quiescent populations showed that the amount of histone RNA was related to the number of cells that entered the S phase. Those cells that synthesized histone RNA and entered the S phase were capable of dividing. This is the first demonstration in a mammalian G1-specific ts mutant that the expression of H2A, H2B, H3, and H4 histone genes depends on the entry of cells into the S phase of the cell cycle.

Animals↗
PubMed1984

[Kidney changes in patients with proliferative diabetic retinopathy].

On 42 patients (25 males, 17 females) at the age of 46.1 +/- 13.4 years with a proliferative diabetic retinopathy clinical and laboratory examinations were performed for the proof of a renal lesion. This disease was found in 59.5% of the cases. In the foreground of the pathological findings were a proteinuria, a restriction of the creatinine clearance and of the concentration power of the kidneys as well as the hypertension. The diabetic nephropathy had its peak of frequency between the 50th and 60th year of age and showed significant relations to the duration of diabetes as well as to be early age of manifestation. Close ophthalmological and nephrological examinations, particularly of the juvenile diabetics, should render possible an early recognition and treatment of the diabetic microangiopathy.

Adult↗
PubMed1984

Clustering of human H1 and core histone genes.

An H1 histone gene was isolated from a 15-kilobase human DNA genomic sequence. The presence of H2A, H2B, H3, and H4 genes in this same 15-kilobase fragment indicates that mammalian core and H1 histone genes are clustered.

Animals↗
PubMed1984

[Furosemide effects in patients with chronic renal insufficiency].

In 8 patients with a slight restriction of the renal function (serum creatinine 150-300 mumol/l), 10 patients with a severe restriction of the renal function (serum creatinine greater than 300-1,200 mumol/l) and in 10 control persons with intact renal function on 2 subsequent days after 40 and 80 mg furosemide the pharmacokinetic data were calculated intravenously from the course of the serum concentration and the renale excretion as well as pharmacodynamic parameters. In comparison to the control persons in patients with creatinine values of more than 200 mumol/l still 4 hours after intravenous injection furosemide could be proved in the serum. According to this the excretion of the unchanged furosemide was clearly decreased in the 24-hour-urine. In decreased renal clearance of furosemide the elimination half-life period was prolonged. In all three groups of patients the diuretic effect of furosemide was very distinctly marked in the first four hours after injection of 40 mg, a doubling of the dose did not increase this effect. Only in the first four hours also an increased excretion of sodium, chloride and calcium occurred; in the 24-hour-collection period no differences between the three groups were the result. The excretion of creatinine and urea-N in the urine was not influenced by furosemide. Thus also in the chronic renal insufficiency there is the indication of the furosemide therapy only then, when the extracellular space or the intravasal volume are enlarged. As individual dose 40 mg are recommended intravenously.

Blood Urea Nitrogen↗
PubMed1984

cis- and trans-Diamminedichloroplatinum(II)-mediated cross-linking of chromosomal non-histone proteins to DNA in HeLa cells.

The cross-linking of chromosomal non-histone proteins to DNA in isolated nuclei or intact HeLa cells exposed to different concentrations of cis- and trans-diamminedichloroplatinum(II) (cis- and trans-DDP) for various time intervals was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunochemical methods. Both the cis- and the trans-DDP cross-linked significant numbers of chromosomal non-histone proteins to the DNA. The quantity and the types of the cross-linked proteins depended on the time of incubation as well as on the concentrations of the drugs. The immunochemical techniques revealed that both the 0.35 M sodium chloride insoluble and soluble chromosomal non-histone proteins were cross-linked to the DNA by both isomers. The action of cis- and trans-DDP was reversed and/or blocked by thiourea or 2-mercaptoethanol. Pretreatment of isolated nuclei or chromatin with iodoacetamide or N-ethylmaleimide did not prevent the DNA-protein cross-linking.

Chromosomal Proteins, Non-Histone↗
PubMed1984

Inhibition of DNA replication coordinately reduces cellular levels of core and H1 histone mRNAs: requirement for protein synthesis.

Cellular levels of H1 and core histone mRNAs have been examined in exponentially growing HeLa S3 cells as a function of DNA synthesis inhibition under varying concentrations of three DNA synthesis inhibitors. Total cellular histone mRNAs were analyzed by Northern blot hybridization, and their relative abundance was shown to be stoichiometrically and temporally coupled to the rate of DNA synthesis. In the presence of cytosine arabinoside, hydroxyurea, or aphidicolin, a rapid, proportionate decrease of histone mRNA levels resulted in an apparent mRNA half-life of less than 10 min. Using inhibitors of transcription and translation, we show that transcription is not necessary for the coordinate decrease of histone mRNA levels that occurs when DNA synthesis is inhibited. When protein synthesis is inhibited by addition of cycloheximide, core and H1 histone mRNAs do not decrease in parallel with reduced rates of DNA synthesis but instead are stabilized and accumulate with time, thus uncoupling histone mRNA levels and DNA replication. These last observations suggest that protein synthesis, either of histones or of some unidentified regulatory molecules, is required for the stoichiometric turnover of H1 and core histone mRNAs coordinate with reduced rates of DNA synthesis.

Aphidicolin↗
PubMed1984

Requirement of protein synthesis for the coupling of histone mRNA levels and DNA replication.

H1 and core histone mRNA levels have been examined in the presence of protein synthesis inhibitors with different mechanisms of action. Total HeLa cell RNAs were analyzed by Northern Blot hybridization using cloned human histone genes as probes. Inhibition of DNA replication resulted in a rapid decline in histone mRNA levels. However, in the presence of cycloheximide or puromycin, H1 and core mRNAs did not decrease in parallel with DNA synthesis, but were stabilized and accumulated. Inhibition of DNA synthesis with hydroxyurea after the inhibition of protein synthesis did not lead to a decline in histone mRNA levels. These results suggest that synthesis of a protein(s)--perhaps a histone protein(s)--is required for the coordination of DNA synthesis and histone mRNA levels.

Cloning, Molecular↗