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Biomedical subjects

S Klein

Publications and source records attributed to S Klein.

At least 19 recordsLinked to original sources
PubMed1992

Relevance of environmental alkylating agents to repair protein O6-alkylguanine-DNA alkyltransferase: determination of individual and collective repair capacities of O6-methylguanine.

The repair capacity for O6-methylguanine was determined in cell homogenates of peripheral blood lymphocytes of 35 automobile industry workers, exposed to rubber and tires, and of 35 clinical workers, handling cancer chemotherapeutic agents, compared to control groups. lambda-Phage DNA containing one 32P-labeled O6-methylguanine in each BamHI site was used as substrate for the repair protein O6-alkylguanine-DNA alkyltransferase (AGT). The clinical personnel showed in the mean a highly significantly (P = 0.0014, Wilcoxon U test, Mann and Whitney) reduced activity of the repair enzyme [3.28 +/- 0.28 (SEM) fmol AGT/micrograms DNA] as compared to 37 control persons (4.88 +/- 0.32 fmol AGT/micrograms DNA). The mean AGT value of the automobile industry workers (4.40 +/- 0.28 fmol AGT/micrograms DNA) was not significantly different (P = 0.1303) from the mean of 38 examined controls (5.00 +/- 0.28 fmol AGT/micrograms DNA). By dividing these employees into subgroups according to their different work environments (handling of rubber fittings, tire mounting, and tire storage, respectively) the mean AGT value of the 15 tire storage workers was significantly (P = 0.0270) lower (3.80 +/- 0.36 fmol AGT/micrograms DNA) than the mean value of the controls. The interindividual variations in the activity of AGT were 5.1- and 6.5-fold in the control groups and 5.6-fold for the automobile industry workers; the largest variations were found in the group of the clinical personnel with 12.6-fold. No significant correlations between AGT and age, sex, or smoking behavior were observed in any of the groups examined. The decrease in AGT activity will render the afflicted individuals more susceptible to further exposure to methylating agents.

Automobiles↗
PubMed1992

Development of high-affinity 5-HT3 receptor antagonists. 1. Initial structure-activity relationship of novel benzamides.

This report describes the development of novel benzamides which are orally active, highly potent, specific antagonists of 5-HT3 receptors. Described in this first report are the structure-activity relationships that led to novel structures with improved potency and selectivity. From this series of compounds, (S)-28 was identified and selected for further evaluation as a 5-HT3 receptor antagonist. Compared with 5-HT3 antagonists such as GR 38032F, BRL 43694, and metoclopramide, (S)-28 was most active in (a) inhibiting binding to 5-HT3 receptor binding sites in rat entorhinal cortex with an Ki value of 0.19 nM and (b) blocking cisplatin-induced emesis in the ferret with an ED50 value determined to be 9 micrograms/kg po.

Animals↗
PubMed1992

Development of high-affinity 5-HT3 receptor antagonists. 2. Two novel tricyclic benzamides.

Two new classes of potent 5-HT3 agents have been developed and examined as inhibitors of cytotoxic drug induced emesis in the ferret and dog. The absolute configuration of the most active molecules 10 and 18 have been determined by X-ray crystallography. These two compounds are more potent than known 5-HT3 receptor antagonists both in vivo and in vitro in blocking 5-HT3 receptor activation and preventing chemotherapeutic induced emesis. Compared with 5-HT3 antagonists, such as GR 38032F, zacopride, BRL 43694, and ICS 205-930, compound 10 was more potent in (1) inhibiting binding to 5-HT3 receptor binding sites in rat cortex (Ki = 0.17 nM), (2) blocking the von Bezold-Jarisch effect in the rat (lowest effective dose, 1 microgram/kg iv), and (3) inhibiting 5-HT-induced contraction of guinea pig ileum (lowest effective concentration, 10(-9) M). This novel agent was as effective given po as when given iv in reducing cisplatin-induced emetic episodes in the ferret (ED50 = 4 micrograms/kg iv or po). A 1 mg/kg po dose of 10 virtually abolished cisplatin-induced emesis for 10 h in the ferret. However, it was inactive against apomorphine or copper sulfate-induced vomiting. These data, coupled with receptor binding studies of ligands for D2-dopamine, a1, a2, 5-HT1, 5-HT2, and muscarinic receptors demonstrate that 10 is a highly selective 5-HT3 receptor antagonist with remarkable potency in vivo.

Amides↗
PubMed1992

Multiple sites for double-strand breaks in whole meiotic chromosomes of Saccharomyces cerevisiae.

We present a scheme for locating double-strand breaks (DSBs) in meiotic chromosomes of Saccharomyces cerevisiae, based on the separation of large DNA molecules by pulsed field gel electrophoresis. Using a rad50S mutant, in which DSBs are not processed, we show that DSBs are widely induced in S. cerevisiae chromosomes during meiosis. Some of the DSBs accumulate at certain preferred sites. We present general profiles of DSBs in chromosomes III, V, VI and VII. A map of the 12 preferred sites on chromosome III is presented. At least some of these sites correlate with known 'hot spots' for meiotic recombination. The data are discussed in view of current models of meiotic recombination and chromosome segregation.

Chromosome Aberrations↗
PubMed1992

Assay for O6-alkylguanine-DNA-alkyltransferase using oligonucleotides containing O6-methylguanine in a BamHI recognition site as substrate.

Double-stranded oligonucleotides, 40 bases in length containing an O6-methylguanine in a BamHI restriction site, were developed as substrates for the determination of human O6-alkylguanine-DNA-alkyltransferase (AGT). The assay proved highly sensitive and quantitative. After incubation of the 5'-end-labeled oligonucleotides with cell homogenates of peripheral blood lymphocytes, the DNA was digested with BamHI. Cleavage with this restriction enzyme did not occur in the O6-methylguanine-containing oligonucleotide unless the fragment was repaired. The cleaved oligonucleotide was separated from the intact parent oligonucleotide by reverse-phase high-performance liquid chromatography. Calculation of the AGT content was achieved by integrating the radioactivity of the peak corresponding to the digested fragment, which is equal to the molar amount of repaired oligonucleotide and corresponds directly to the molar AGT content in the lymphocyte homogenate.

Base Sequence↗
PubMed1992

In vivo assessment of the metabolic alterations in glucagonoma syndrome.

Stable-isotope methodology and indirect calorimetry were used to evaluate metabolic abnormalities in a patient with glucagonoma syndrome manifested by 17% body weight loss, hypoaminoacidemia, and hyperglycemia. Energy expenditure (26 kcal/kg) was the same as that predicted by the Harris-Benedict equation. The rate of appearance (Ra) of intracellular leucine (2.70 mumol/kg/min), an index of protein breakdown, was normal, although the percentage of leucine flux oxidized (31%), an index of amino acid catabolism, was 50% greater than the normal mean value. Glucose Ra in plasma (12.9 mumol/kg/min), representing hepatic glucose production, and glycerol Ra in plasma (3.04 mumol/kg/min), a measurement of whole-body lipolysis, were 15% and 25% greater, respectively, than mean values found in normal volunteers. These results suggest that long-term alterations in energy, leucine, glucose, and lipid metabolism in patients with glucagonoma are minimal. However, small long-term metabolic alterations caused by glucagon excess, in conjunction with chronic negative energy balance, could be responsible for the weight loss, hypoaminoacidemia, and hyperglycemia observed in this patient population.

Adult↗
PubMed1992

Generalized lipodystrophy: in vivo evidence for hypermetabolism and insulin-resistant lipid, glucose, and amino acid kinetics.

Stable isotope tracers and indirect calorimetry were used to evaluate whole-body energy, glucose, lipid, and amino acid metabolism in a patient with generalized lipodystrophy during basal conditions and in response to insulin therapy. The results were compared with those obtained in previous studies in normal volunteers. The basal rate of glucose production (33.7 mumol/kg.min) was three times higher than normal. The basal rate of glycerol appearance in blood, an index of lipolysis, was 60% greater than normal when expressed per kilogram body weight (3.82 mumol/kg.min), but was more than 10 times normal when expressed per kilogram body fat mass (123.2 mumol/kg.min) because of the marked decrease in body fat in our patient (3% of total body weight). Leucine rate of appearance, an index of protein breakdown, and nonoxidative leucine disposal, an index of protein synthesis, were also greater than normal. Resting energy expenditure (REE) was 30% greater than normal. The effect of insulin infusion on these metabolic parameters was markedly blunted. These metabolic abnormalities help explain many of the clinical findings such as hyperglycemia, hypertriglyceridemia, fat depletion, hepatomegaly, and steatosis observed in patients with lipodystrophy. Ineffective insulin function in many tissues appears to be an important factor in the pathophysiology of lipodystrophy.

Adult↗
PubMed1992

Heterogeneous expression of c-myb protein in human leukemia detected by simultaneous two color flow cytometric analysis.

The expression of c-myb mRNA and protein was analyzed in fresh leukemic cells by Northern-blot analyses and by immunofluorescent staining using monoclonal c-myb specific antibodies. Staining of the cells was evaluated by flow cytometry. The results demonstrate c-myb mRNA expression predominantly in acute lymphocytic leukemia (ALL, 4/4 cases), acute myeloic leukemia (AML, 17/17) and chronic myeloic leukemia (CML, 12/12) but rarely in chronic lymphocytic leukemia (CLL, 1/17). Immunofluorescent analyses revealed expression of c-myb protein in the nucleus of ALL (5/7) and AML (9/9) with a good correlation of c-myb-positive cells and with the number of proliferating (Ki67-positive) blast cells.

Antigens, Surface↗
PubMed1992

[Results of animal experiment study of a new enucleation filling of bio-vitroceramics--Bioverit I and II (bioactive and biocompatible)].

The results with two new enucleation prothesis made of Bioverit are presented. After unilateral enucleation 14 rabbits received bioreactive, 14 rabbits biocompatible and 9 rabbits nylon prostheses. Implantation periods: 1-13 months. The tissue surrounding of the prostheses was studied histologically, the ceramic electron microscopically. Of 28 ceramic prostheses, 26 were adapted very well. Bioverit ist excellently suited as orbital prosthetic material, even half-open implants are possible.

Animals↗
PubMed1992

A comparison of interferon-Con1 with natural recombinant interferons-alpha: antiviral, antiproliferative, and natural killer-inducing activities.

The antiviral, antiproliferative, and natural killer (NK) cell activation by recombinant human interferon-consensus (IFN-Con1) has been compared with that of two other type I IFNs: IFN-alpha 2a (Roferon) and IFN-alpha 2b (Intron A). The specific activity (antiviral units/mg) of IFN-Con1 was 10-fold higher than that of the other two IFNs in the vesicular stomatitis virus (VSV)-HeLa antiviral assay. The antiproliferative activity on a molar basis of IFN-Con1 on Daudi cells and Eskol (a human leukemic hairy cell-like cell line) was significantly greater than that of IFN-alpha 2a and IFN-alpha 2b. IFN-Con1 also enhanced or induced NK cell killing of target cells to a greater extent than that of IFN-alpha 2a and IFN-alpha 2b. However, on antiviral unit basis, the activities were similar. These results would suggest that IFN-Con1 may be more effective at lower protein concentrations in clinical applications than other available IFNs.

Amino Acid Sequence↗
PubMed1992

Activation of cytokines in Hodgkin's disease.

The complex histological pattern in Hodgkin's disease and in part in large cell anaplastic lymphomas (ALCL) suggests that close interactions exist between the tumor cells and reactive bystander cells. These interactions are most likely mediated by short ranged cytokines. The production of cytokines was analyzed in primary tissues and cell lines from Hodgkin's disease and ALCL by enzyme linked immunosorbent tests (ELISA), Northern blotting, immunohistological staining and in situ hybridization experiments. Our results indicate that Hodgkin's disease derived cell lines produce a variety of cytokines, such as IL1 alpha, IL4, IL5, IL6, IL8, IL9, TNF alpha and TNF beta but not IL1 beta, IL2, IL3 and G-CSF. In addition, the receptors for IL6 were detected in some of the cell lines. The expression of IL6 and IL6 receptors and IL9 has been confirmed for some primary tissues of Hodgkin's disease. From our data, we conclude that IL6, IL9 and additional cytokines are involved in the biology of Hodgkin's disease and ALCL.

Cell Line↗
PubMed1992

A directional, high-frequency chromosomal mobilization system for genetic mapping of Rhizobium meliloti.

A system for mapping of the Rhizobium meliloti chromosome that utilizes transposon Tn5-Mob, which carries the mobilization site of IncP plasmid RP4 (R. Simon, Mol. Gen. Genet. 196:413-420, 1984), was developed. Insertions of Tn5-Mob that were located at particular sites on the R. meliloti chromosome were isolated and served as origins of high-frequency chromosomal transfer when IncP tra functions were provided in trans. This approach is, in principle, applicable to any gram-negative bacterium in which Tn5 can transpose and into which IncP plasmids can conjugate.

Chromosome Mapping↗
PubMed1992

Mechanism of regulation of glucose production by lipolysis in humans.

The relationship between the rate of lipolysis and rate of glucose production (Ra) was investigated in 14- and 86-h fasted humans. [6,6-2H]glucose and [2H]5glycerol were infused to measure glucose and glycerol Ra in response to infusions of nicotinic acid in 14- and 86-h fasted subjects (protocol 1). The response of glucose Ra to nicotinic acid alone and nicotinic acid plus unlabeled glycerol was also measured in 86-h fasted subjects (protocol 2). After a 14-h fast, nicotinic acid caused a 30% decrease in plasma insulin levels and a marked (66%) decrease in plasma free fatty acid levels but did not have any significant effect on glucose Ra and concentration. After 86 h of fasting, nicotinic acid decreased glycerol Ra and hence lipolytic rate by approximately 60%. This caused a significant decrease (P less than 0.05) of 16-20% in glucose Ra and uptake. This decrease in glucose Ra was abolished when unlabeled glycerol was also infused with nicotinic acid to maintain glycerol Ra. These findings suggest that, in normal humans, a decrease in the rate of lipolysis regulates glucose Ra via its effect on the availability of glycerol for gluconeogenesis.

Adult↗
PubMed1992

Carbohydrate restriction regulates the adaptive response to fasting.

The importance of either carbohydrate or energy restriction in initiating the metabolic response to fasting was studied in five normal volunteers. The subjects participated in two study protocols in a randomized crossover fashion. In one study the subjects fasted for 84 h (control study), and in the other a lipid emulsion was infused daily to meet resting energy requirements during the 84-h oral fast (lipid study). Glycerol and palmitic acid rates of appearance in plasma were determined by infusing [2H5]glycerol and [1-13C]palmitic acid, respectively, after 12 and 84 h of oral fasting. Changes in plasma glucose, free fatty acids, ketone bodies, insulin, and epinephrine concentrations during fasting were the same in both the control and lipid studies. Glycerol and palmitic acid rates of appearance increased by 1.63 +/- 0.42 and 1.41 +/- 0.46 mumol.kg-1.min-1, respectively, during fasting in the control study and by 1.35 +/- 0.41 and 1.43 +/- 0.44 mumol.kg-1.min-1, respectively, in the lipid study. These results demonstrate that restriction of dietary carbohydrate, not the general absence of energy intake itself, is responsible for initiating the metabolic response to short-term fasting.

Adaptation, Physiological↗
PubMed1992

Positive thinking reduces heart rate and fear responses to speech-phobic imagery.

30 speech-anxious subjects imagined a phobic speech scene 10 times. The experimental conditions varied according to whether the subjects engaged in positive, neutral, or negative thinking prior to each scene presentation. Heart rate and self-reports of fear were measured during the imagery periods. Positive thinking just before visualization of the phobic images reduced both subjective anxiety about speech and cardiovascular responses.

Adolescent↗
PubMed1992

Hodgkin and Reed-Sternberg cells express interleukin 6 and interleukin 6 receptors.

Interleukin 6 (IL-6) is a pleiotropic lymphokine which can stimulate a variety of cells including B and T lymphocytes. It has been suggested that IL-6 plays a crucial role in several diseases such as human plasmacytoma, cardiac myxoma or Castleman's Disease by autocrine or paracrine stimulation. To analyse whether IL-6 is involved in the biology of Hodgkin's Disease (HD), we investigated the expression of IL-6 and IL-6 receptor (IL-6R) in cell lines and primary specimens from patients with HD. IL-6 specific transcripts were detected in three out of six HD derived cell lines by Northern blot analysis and in the culture supernatants of four HD derived cell lines by ELISA. Its biological activity was confirmed by proliferation of an IL-6 dependent cell line. By in-situ hybridization experiments IL-6 specific transcripts were detected in Hodgkin (H) and Reed-Sternberg (RS) cells in primary tissues in two out of three patients. mRNAs specific for the IL-6 receptor were detected in five HD derived cell lines. Staining of HD derived cell lines revealed expression of the receptor molecules in five cell lines; Western blot experiments confirmed the 80kDa receptor protein in the cells. Immunohistology in primary specimens revealed expression of the receptor molecules on H and RS cells in 8 out of 16 cases with HD. Expression was mostly detected in the mixed cellularity subtype of HD. Elevated levels of IL-6 were detected in the sera of more than 50% of patients with HD. Taken together our data suggest that IL-6 might be involved in the biology of HD.

Adolescent↗