Search PubMed⌕ Search

Biomedical subjects

J Stein

Publications and source records attributed to J Stein.

At least 415 records · Page 23Linked to original sources
PubMed1984

Cell cycle regulation of human histone H1 mRNA.

A cloned genomic DNA fragment containing a human histone H1 gene has been used to analyze histone H1 gene expression in two human cell lines (HeLa S3 and WI-38). The cellular abundance of histone H1 mRNA was compared with that of core (H2A, H2B, H3, and H4) histone mRNAs as a function of the cell cycle: core and H1 histone mRNA levels are related both to each other and to the apparent rate of DNA synthesis and are rapidly destabilized after DNA synthesis inhibition. The use of three synchronization protocols, and of transformed and normal diploid cells in culture, suggests that the detected core and H1 histone mRNA levels are regulated by similar mechanisms in continuously dividing human cell lines and nondividing cells stimulated to proliferate.

Cell Cycle↗
PubMed1984

Coordinate replication of members of the multigene family of core and H1 human histone genes.

Cells of the K562 human erythroleukemia cell line were obtained in different stages of the cell cycle by centrifugal elutriation. The cells had been previously labeled for 2 hr with BrdUrd so that BrdUrd-DNA synthesized during four different selected intervals of the S phase could be isolated. This DNA was used to determine the temporal replication during S phase of EcoRI segments containing histone genes. Cloned human genomic segments containing the core histone genes (H2A, H2B, H3, and H4), H2A and H2B pseudogenes, and the H1 gene were prepared. The genomic inserts were excised from these plasmids, nick-translated, and used as hybridization probes. The results with different probes compared on the same and on independently prepared DBM-paper transfers indicate that all of these histone genes replicate during the first half of the S phase. These genes were not among the earliest to replicate in the K562 cell line. Similar studies were carried out with HeLa cells in which EcoRI segments containing the H4 histone and H2A and H2B pseudogenes were found to replicate during the first half of the S phase. These histone genes replicate during the interval of the S phase when histone mRNA appears in the cytoplasm at the maximal rate. The possible relationship between these events is discussed.

Base Sequence↗
PubMed1984

Evidence for a human histone gene cluster containing H2B and H2A pseudogenes.

Not all members of the human histone gene family are functional. We have isolated a human H2B pseudogene that contains alterations in the protein-coding sequences as well as in the 3' and 5' flanking sequences that preclude expression of a functional H2B histone protein. There are three modifications in the amino acid-coding region: a single-base deletion producing a frame shift, a single-base substitution resulting in a codon change from serine to tryptophan (an amino acid not present in histones), and the absence of a stop codon. Analysis of nucleotide sequences upstream from the AUG start signal indicates the absence of a "TATA" box and other putative consensus regulatory sequences. In the 3' flanking region, a highly conserved block of 22 nucleotides that exhibits hyphenated dyad symmetry is displaced downstream. Within the same genomic segment, the adjacent H2A histone gene is missing 12 nucleotides, resulting in a deletion of four amino acids in a highly conserved region of the protein.

Amino Acid Sequence↗
PubMed1984

Delineation of the site of action of guanabenz in the renal tubule.

Guanabenz, a centrally acting alpha 2-agonist, has been shown to lower blood pressure (BP) while maintaining glomerular filtration rate and increasing water and solute excretion. The site and mechanism of the increased solute excretion are still unclear. To evaluate the effect of guanabenz on water and solute reabsorption in the collecting duct, Munich Wistar rats were utilized in micropuncture experiments. Micropuncture samples were obtained from the most proximal portion (base) of the collecting duct and the most distal part (tip). In an initial group of hydropenic rats, collecting duct water and chloride (Cl) reabsorption were evaluated during a control and experimental period during which guanabenz was infused at 20-40 micrograms/kg/min. Although the mean drop in BP was 18 mm Hg after guanabenz infusion, at any given rate of Cl delivery, the reabsorption was less than that for the control period. Another group of studies utilizing the plasma repletion method to increase Cl excretion was used to evaluate collecting duct reabsorption. BP was lowered in rats by an aortic snare to approximately 95 mm Hg and papillary collecting duct (PCD) samples were obtained. The snare was then released and 100-400 micrograms/kg/min of guanabenz was infused and the rate adjusted to produce a drop in BP similar to that of the initial period. During the control period, PCD fluid to plasma inulin ratios were 23.1 +/- 4.3 and 37.3 +/- 4.6 at the base and tip, respectively. This ratio was decreased to 10.9 +/- 3.1 and 15.7 +/- 4.6 at the base and tip puncture sites, respectively, during guanabenz infusion. PCD chloride reabsorption during the initial period was 40.3% +/- 7.0% of the load delivered. During the guanabenz infusion, however, only 12.8% +/- 3.4% of the delivered load was reabsorbed (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Insulin levels during lactate infusion.

To determine whether the lactate-induced panic of patients with panic attacks results from hyperinsulinism balanced by epinephrine-enhanced gluconeogenesis, the authors measured 10 subjects' insulin levels exactly when the lactate-induced attacks began. The insulin levels were normal.

Adult↗
PubMed1984

Response to hyperventilation in a group of patients with panic disorder.

Twelve patients with DSM-III diagnoses of panic disorder and four normal volunteers were studied during hyperventilation of room air and increased ventilation stimulated by 5% CO2. Patients also underwent sodium lactate infusion. Eight of the patients had a panic attack during sodium lactate infusion, seven during CO2 inhalation, and three during room-air hyperventilation. Since CO2 increases the firing of the locus ceruleus, and since sodium lactate infusion is known to increase cerebral CO2, these findings are consistent with other evidence implicating the locus ceruleus in panic anxiety.

Adult↗
PubMed1983

Influence of DNA synthesis inhibition on the coordinate expression of core human histone genes during S phase.

Core histone mRNA metabolism has been examined in S phase HeLa cells recovering from DNA synthesis inhibition by 1 mM hydroxyurea. Using cloned human histone genes as probes for histone mRNA quantitation, the response to and recovery from DNA synthesis inhibition is shown to depend on the position of the cell with respect to the initiation of DNA replication. The incorporation of 3H-uridine into multiple histone mRNAs in recovering cells does not exceed preinhibition levels, and as this incorporation is maximal in early S phase, the synthesis of core histone mRNA is apparently related to the ordered replication of the genome. The total histone mRNA present in interrupted S phase cells after recovery is not significantly different from that present in control cells, and a temporal and functional coupling between histone mRNA levels and the relative rate of DNA synthesis is maintained in perturbed cells.

DNA Replication↗
PubMed1983

Structure and in vitro transcription of a human H4 histone gene.

A human H4 histone gene was isolated and the nucleotide sequences of the mRNA coding as well as the 5' and 3' flanking regions were determined. No intervening sequences were found in this gene. A series of sequences which have been assigned putative regulatory roles in histone genes and/or in other genes were identified both upstream and downstream from the H4 histone protein coding region. Deletion mutants were constructed by BAL-31 nuclease digestion of sequences in the 5' flanking region of this H4 histone gene and were assayed in an in vitro transcription system. No regions upstream from the TATA box were required for site specific initiation in vitro. Data are presented which suggest that sequences located downstream from the 3' end of the coding region may influence the in vitro transcription of this human H4 histone gene.

Amino Acid Sequence↗
PubMed1983

Crosslinking of chromosomal proteins to DNA in HeLa cells by UV gamma radiation and some antitumor drugs.

Immunochemical techniques were used to investigate the protein-DNA crosslinking by ultraviolet (UV) and gamma radiation as well as 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) or cis- and trans-diamminedichloroplatinum II (cis-DDP and trans-DDP). Antisera to 0.35 M NaCl extract and 0.35 M NaCl residue of HeLa nuclei were employed. Both gamma and UV irradiation, exposure to cis- or trans-DDP and, to a lesser extent, BCNU, resulted in crosslinking of various antigens to the DNA. Although several antigens were crosslinked by all the employed agents, other exhibited agent-specific crosslinking patterns.

Carmustine↗
PubMed1983

Coordinate regulation of multiple histone mRNAs during the cell cycle in HeLa cells.

Core histone gene expression in HeLa S3 cells has been examined as a function of the cell cycle using cloned human histone gene probes. Total cellular histone mRNAs were analyzed by Northern blot analysis, and their relative abundance shown to be temporally coupled to DNA synthesis rates in S phase. The in vivo incorporation of 3H-uridine into at least fifteen heterologous histone mRNAs (in one hour pulse intervals at various times in the cell cycle), was monitored by hybrid selection. Hybridized RNAs were eluted and resolved electrophoretically to give both a quantitative and qualitative assay for multiple mRNA species. Maximal incorporation of 3H-uridine into histone mRNAs precedes their maximal accumulation, indicating that transcriptional regulation is predominant in early S phase. The turnover of histone mRNAs in late S occurs in the presence of a reduced apparent transcription rate, indicating that post-transcriptional regulation is predominant in late S. All the detected multiple histone mRNAs are coordinately regulated during the HeLa cell cycle.

Cell Cycle↗
PubMed1983

Reagan's cancer wars.

Explore the source record for details and available documents.

Carcinogens, Environmental↗
PubMed1983

Combined free flap and local muscle flap for lower extremity salvage.

Reconstruction of extensive compound lower-extremity injuries may require the use of local flaps or free-tissue transfer. When either method alone is inadequate for reconstruction of two isolated defects on the same lower extremity, a combined approach may be utilized to reconstruct a functional lower extremity.

Adult↗
PubMed1983

[Percutaneous-peripheral vena cava catheterization in intensive care of premature and newborn infants. Comparison of Shaw's silastic catheter with the customary polyvinyl catheter].

Central venous catheters inserted via peripheral veins are commonly used in neonatal intensive care. Handling of two commonly available catheters made of different materials were compared during application in 85 neonates under intensive care. Polyvinylchloride and silicone rubber were used as catheter material. Advantages of silicone rubber catheter were detected especially in very low birth weight premature infants. Successful puncture of the peripheral veins and correct positioning could be performed in a higher proportion of these babies than when using polyvinylchloride-catheters. The insertion of polyvinyl-catheters needs shorter time of manipulation and during infusion we found a significantly lower incidence of mechanical problems with the catheter.

Catheterization↗