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Biomedical subjects

I Klein

Publications and source records attributed to I Klein.

17 recordsLinked to original sources
PubMed1992

Time course of the in vivo effects of thyroid hormone on cardiac gene expression.

The rate of response to thyroid hormone on cardiac growth, heart rate, and the relative changes in messenger RNA (mRNA) coding for alpha- and beta-myosin heavy chain (MHC), slow sarcoplasmic reticulum calcium-adenosine triphosphatase, and thyroid hormone receptors in ventricular tissue of hypothyroid rats was investigated. Hypothyroid rats had significantly smaller hearts, with slower heart rates and expressed no alpha-MHC mRNA as analyzed by an S1 nuclease protection assay when compared to euthyroid animals that expressed 79% alpha-MHC. Twelve hours after treating hypothyroid rats with 20 micrograms of L-T4, detectable levels of alpha-MHC mRNA were present and the shift to alpha-MHC mRNA was complete by 72 h of treatment. Northern blot analysis showed that hypothyroidism resulted in a 60% decrease in the level of sarcoplasmic reticulum calcium-adenosine triphosphatase mRNA which increased after 12 h of T4 administration and was 2.5-fold (P less than 0.05) greater than euthyroid levels after 72 h. In contrast, thyroid hormone receptor mRNA levels measured in poly(A)+ RNA were elevated in hypothyroid rats and decreased to euthyroid levels within 24 h after thyroid hormone treatment. These changes in cardiac gene expression occurred simultaneously with changes in both cardiac size and heart rate. The current studies characterize the coordinated changes and the time course for gene expression that occur in the hypothyroid heart after acute T4 administration.

Animals↗
PubMed1978

Effect of liposomes containing cholesterol on adenylate cyclase activity of cultured mammalian fibroblasts.

Liposomes prepared with cholesterol and dipalmitoyl phosphatidylcholine were incubated with a clone of normal rat kidney fibroblast of cells in culture. The cells took up [14C]cholesterol in proportion to the concentration of liposomes in the incubation medium, and the uptake increased with time over the four hours of study. Two cell membrane enzymes, adenylate cyclase and (Na+ + K+)-ATPase, exhibited decreased activity after treatment with cholesterol-containing liposomes. The decrease in adenylate cyclase activity was directly proportional to the uptake of [14C]cholesterol. When a variety of subclones of NRK 5W were examined some were found to respond to cholesterol treatment and some did not. These data are consistent with the view that membrane cholesterol content plays a role in controlling the activity of some plasma membrane enzymes.

Adenosine Triphosphatases↗
PubMed1978

Differentiation of brain damage among low IQ subjects with three projective techniques.

Using a battery of three projective techniques (Rorschach, Hand Test, Bender-Gestalt) only slight discrimination was found between low IQ subjects classified according to the presence or absence of brain trauma (exogenous vs endogenous), while substantial discrimination was obtained between the same subjects categorized in terms of "lower" (60-74) and "higher" (75-89) FS WAIS IQ. All four groups used in this study had been first equated on sex and age. Results were interpreted as supporting the position that some sort of brain impairment underlies most or all retardation. Question was raised concerning the efficacy of projective techniques for diagnosing organicity in subjects of average or better intelligence.

Adolescent↗
PubMed1977

Importance of Holter monitoring in patients with periodic cerebral symptoms.

Holter monitoring was used in 358 patients with symptoms of intermittent dizziness, blackout, or both. The neurological findings in all patients were normal. None manifested evidence of a pertinent arrhythmia on the one-minute resting ECG; 8.9% of the patients demonstrated arrhythmias known to correlate with cerebral symptoms; and 11.2% demonstrated "predisposing" arrhythmias, ie. rhythms that in and of themselves may not precipitate symptoms but predispose to arrhythmias that do. The latter category included short bursts of ectopic tachycardia and intermittent short-duration asystole. High-frequency ectopic beats were observed in 24.6%. In almost every patient in whom intermittent arrhythmias precipitated symptoms there were many "predisposing" arrhythmias of short duration that occurred during the asymptomatic period. A comparison of 12- and 24-hour recordings demonstrated an increase in pertinent arrhythmias from 13.8 to 22.7%.

Adult↗
PubMed1977

Cowpea mosaic virus RNAs have neither m7GpppN ... nor mono-, di- or triphosphates at their 5' ends.

32P-labeled cowpea mosaic virus (CPMV) RNAs were analyzed for their 5' termini by three different fingerprinting standard procedures. These analyses showed unequivocally that CPMV RNAs lack a structure like m7GpppN ... at their 5' termini. In addition, neither mono-, di- or triphosphorylated [(p)(p)pN ....] termini were found in the respective fingerprints. The inability to label the 5' termini treatment with gamma-32P-ATP and polynucleotide kinase, either per se or after pretreatment with alkaline phosphatase, strongly suggests the absence of a free 5'-OH and a free 5'-phosphate at the 5' terminal nucleotide in CPMV RNAs. The various analyses also showed that no 2' -O-methylated nucleotides, N6-methyladenosines or pseudo-uridines are present in CPMV RNAs.

Adenosine Triphosphate↗
PubMed1977

WAIS differences between murderers and attackers referred for evaluation.

12 first and second degree murderers were matched on sex and age with subjects who had perpetrated aggressive interpersonal attacks short of homicide. Both groups had been referred for psychological testing by courts and social agencies. A substantial and significant difference in IQ was found in favor of the attackers over the murderers. Results were interpreted as lending credence to the hypothesis that differences in IQ exist among important sub-populations of murderers.

Adult↗
PubMed1975

Occurrence of polyamines in coliphages T5, phiX174 and in phage-infected bacteria.

The polyamine spermidine and the diamine putrescine have been detected in coliphages T5 and phiX174. Polyamines were identified by thin-layer chromatography and mass-spectrometry of dansyl derivatives, as well as by ion-exchange chromatography. In phiX174 phages, polyamines were sufficient to neutralize 0.5% of DNA phosphates. The polyamine content of T5 phages depended on growth media and purification procedures, but at least 1% of DNA phosphates were neutralized by polyamines. After infection, an increase in cellular polyamine was noticed. This increase paralleled variations in ornithine decarboxylase activity.

Carboxy-Lyases↗
PubMed1975

Glucagon and adenylate cyclase: binding studies and requirements for activation.

Solubilization of myocardial adenylate cyclase abolished responsiveness to glucagon and catecholamines, two of the hormones which activate the membrane-bound enzyme. Adenylate cyclase freed of detergent by DEAE-cellulose chromatography continues to remain unresponsive to hormone stimulation. However, adding purified bovine brain phospholipids--phosphotidylserine and monophosphatidylinositol--restored responsiveness to glucagon and catecholamines, respectively. 125-i-glucagon binding appeared to be independent of phospholipid, since equal binding was observed in the presence or absence of detergent and in the presence or absence of phospholipids. Chromatography of the solubilized preparation on Sephadex G-100 WAS CHARACTERIZED BY 125-I-glucagon binding and fluoride-stimulatable adenylate cyclase activity appearing in the fractions consistent with the void volume, suggesting a molecular weight greater than 100,000 for the receptor-adenylate cyclase complex. Prior incubation of the binding peak with 125-I-glucagon and rechromatography of the bound glucagon on Sephadex G-100 shifted its elution to a later fraction consistent with a smaller-molecular-weight peak. The molecular weight of this material was 24,000 to 28,000, as determined by SDS polyacrylamide gel electrophoresis. The latter findings are consistent with a dissociable receptor site for glucagon on myocardial adenylate cyclase.

Adenylyl Cyclases↗