Search PubMed⌕ Search

Biomedical subjects

G Steiner

Publications and source records attributed to G Steiner.

At least 217 records · Page 12Linked to original sources
PubMed1987

The chromogenicity and quantitation of apoB-100 and apoB-48 of human plasma lipoproteins on analytical SDS gel electrophoresis.

ApoB-100 and apoB-48 may be readily resolved in 3.3% sodium dodecyl sulphate-polyacrylamide gels. This study has characterized the relative chromogenicities (staining intensity/micrograms protein) of human apoB-100 and apoB-48 in various lipoprotein classes with Coomassie Brilliant Blue (R250) upon SDS-PAGE. The relation between dye uptake and the mass of each apoB species in any lipoprotein preparation, was linear at least within the concentration range of total apoprotein B which is optimally resolved in these gels (20-50 micrograms total apoprotein B), and was a function of the density of the particular lipoprotein fraction under investigation. There was a constant and characteristic difference between the chromogenicity for apoB-100 and that for apoB-48 as determined from the slopes of their respective chromogenicity curves. The slope of the lines describing staining intensity vs. protein mass for both apoB-100 and apoB-48 decreased as the density of the lipoprotein fraction increased. The slope of the line for apoB-100 was steeper than that for apoB-48 (i.e. chromogenicity apoB-100 greater than apoB-48) in all lipoprotein fractions where both were present. The relationship between the slopes of the lines for apoB-100 and apoB-48 was constant regardless of the density of the lipoprotein fraction. The chromogenicity curves for apoB-100 and for apoB-48 obtained when lipoprotein samples were applied to gels in concentrations conventionally used for this technique (i.e. 20-100 micrograms total apoB/gel) did not extrapolate to the same point on the ordinate, which precludes the use of a simple ratio or "chromogenicity factor" to describe their relative chromogenicities over this concentration range, Hence, a novel approach was developed to determine the relative mass of apoB-100/apoB-48 in lipoprotein samples, based on their staining characteristics in SDS-PAGE.

Apolipoprotein B-100↗
PubMed1987

Thy-1+ dendritic epidermal cells express T3 antigen and the T-cell receptor gamma chain.

The murine epidermis is a heterogeneous epithelium composed of keratinocytes, melanocytes, Langerhans cells, and a recently described subpopulation (2-3%) of bone-marrow-derived leukocytes with a dendritic morphology and the cell surface phenotype Thy-1+, L3T4-, Lyt-2-. Previous studies have demonstrated that cell lines derived from freshly explanted Thy-1+ dendritic epidermal cells (DEC) have abundant mRNA for rearranged T-cell receptor (TCR) gamma-chain genes. Analysis of Thy-1+ DEC in situ, freshly isolated cell suspensions of Thy-1+ DEC, and long-term Thy-1+ DEC lines demonstrated that 100% of the Thy-1+ DEC reacted with a monoclonal antibody to the epsilon chain of the murine T3 complex and that 40-60% of resident Thy-1+ DEC were also reactive with an antiserum to the TCR gamma chain. Two Thy-1+ DEC lines expressed a disulfide-linked 70-kDa molecule that could be precipitated with an anti-gamma-chain antiserum and could be coprecipitated with an antiserum to the T3 delta chain; the molecule appeared as a single 34-kDa band under reducing conditions. The phenotype of Thy-1+ DEC (T3+, L3T4-, Lyt-2-, TCR gamma chain+) thus resembles that of the recently described subpopulation of murine and human lymphocytes that have been identified in the thymus, peripheral blood, and fetal blood.

Animals↗
PubMed1987

Thy-1+ dendritic epidermal cells belong to the T-cell lineage.

The murine epidermis contains a population of dendritic, Thy-1+ cells (Thy-1+ DEC). Although it is now clear that these cells are of bone marrow origin, extensive morphological, histochemical, and cell-membrane marker studies have not definitively placed them in any known hematopoietic differentiation pathway. Based on the observation that Thy-1+ DEC can be propagated in vitro with Con A and interleukin 2, we have established three cell lines (Tehy 184, Tehy 245, and Yety 245) that can be continuously grown in medium with lectin-lymphokine-rich culture supernatants of rat spleen cells. With the exception of the loss of reactivity with anti-asialo-GM1 antibodies (Tehy 184 and Tehy 245) and the gain of interleukin 2 receptor expression, the cultured cell lines bear the same surface characteristics as freshly isolated Thy-1+ DEC: Thy-1+, Ly-5+, Lyt-1-, Lyt-2-, L3T4-, Ia-, sIg-. Using Southern and RNA gel blot analysis, we now demonstrate that these Thy-1+ DEC-derived cell lines exhibit various patterns of rearrangements in the gene complexes encoding the T-cell receptor (related) beta and gamma chains and contain mature and/or incomplete transcripts from the T-cell receptor alpha- and beta-chain genes, as well as transcripts from the receptor-related gamma-chain genes. Tehy 184 cells, the only cells containing both mature alpha- and beta-chain transcripts, react positively with the F23.1 monoclonal antibody, which recognizes the product of a subset of T-cell receptor beta-chain variable region gene segments. This antibody precipitates a surface protein of 84-88 kDa from these cells that after reduction separates into two 40- to 44-kDa chains, characteristic of Ti alpha/beta heterodimers. These data strongly suggest that Thy-1+ DEC belong to the T-cell lineage and point to the epidermis as a site either of immature thymocyte migration or of extrathymic T-cell differentiation.

Animals↗
PubMed1987

Transfer of newly made triglyceride from hepatocytes to preexisting extracellular very low density lipoproteins.

Previous in vivo studies suggested a new model to describe the metabolism of very low density lipoproteins (VLDL). It was hypothesized that some of the lipoprotein triglyceride was transferred directly from hepatocytes and intestinal mucosal cells into preexisting extracellular VLDL particles. These studies employ an in vitro system to test this hypothesis. Isolated rat liver cells containing newly made radioactive triglyceride were prepared. These cells were incubated in medium to which exogenous VLDL had or had not been added. The presence of extracellular VLDL (rat or human) stimulated the transfer of labeled triglyceride out of the liver cells. This triglyceride was recovered in the medium's VLDL (as determined by its density and its precipitability by MnCl2-heparin or by anti-apoprotein B). Although these studies focussed on VLDL, preliminary data showed that similar triglyceride transfer occurred in the presence of the other apoprotein B containing lipoprotein, low density lipoprotein (LDL). However, in the presence of equivalent amounts of LDL, this triglyceride transfer was less than that seen in the presence of exogenous VLDL. Furthermore, the increased triglyceride released in the presence of LDL occurred entirely in the d less than 1.006 fraction of the medium. That released in the presence of VLDL was recovered in the d greater than 1.006 fraction. Hence, we conclude that the transfer of the newly made triglyceride was from the cell to the extracellular lipoprotein that had been added to the medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

The association of increased levels of intermediate-density lipoproteins with smoking and with coronary artery disease.

Studies were undertaken to determine whether there is an association between elevated levels of intermediate-density lipoproteins (IDL) (Sf 12-60 lipoproteins) and coronary artery disease. Forty-five to sixty-five-year-old men with objectively documented coronary artery disease (n = 58) who were free of known risk factors (diabetes, hypertension, obesity, hyperuricemia, and hypercholesterolemia) were compared with similar men who were free of coronary artery disease (n = 52). Smokers could not be excluded. The coronary artery disease group had a higher rate of cigarette smoking (NS, due to large variations); higher concentrations of triglycerides in their plasma (p = .003) and higher levels of very low-density lipoproteins (VLDL) (p = .007), IDL (p = .016), and low-density lipoproteins (LDL) (p = .04); as well as somewhat lower levels of high-density lipoprotein (HDL) cholesterol (p = .04). Chi-squared analysis demonstrated a strong association between coronary artery disease and IDL apolipoprotein (apo) B (p = .006), coronary artery disease and IDL triglyceride (p = .032), and coronary artery disease and IDL apo B times IDL triglyceride (p = .006) when the top quintile of the population was compared with the bottom quintile for each of these variables. Stepwise logistic regression analysis resulted in rejection of an association between coronary artery disease and HDL cholesterol, plasma triglyceride, VLDL triglyceride, or LDL triglyceride. However, it did show that coronary artery disease was most strongly associated with smoking and that the second strongest association was with IDL.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

[Effects and side effects of somatostatin].

Somatostatin, a peptide hormone with a wide range of actions, was first described in 1973. It is found in neurons of the central and peripheral nervous systems and D cells of the gut and pancreas. Somatostatin acts as a neurotransmitter, a local tissue factor, and a hormone. The intrinsic metabolic effects of somatostatin have been well investigated during the past 10 years. It inhibits the release of gastrointestinal secretions and delays the absorption of glucose and amino acids. Somatostatin inhibits the effects of the release of several of the hormones involved in water-electrolyte homeostasis. It exerts an influence on the regulation of several endocrine and exocrine functions, acting as a "shock absorber". In the nervous system somatostatin functions as a neurotransmitter; intrathecal application causes characteristic changes in the motor system and behavioral aberrations. Furthermore, it has been suggested that it may be a potent analgesic. Side-effects seen during animal experiments are many: marked increases in blood glucose, various behavioral changes, respiratory failure, and death. This article compares the effects and potential side-effects of somatostatin with particular regard to the recent observation that this substance may be a potent analgesic.

Humans↗
PubMed1987

[Relaxation times and proton density of the healthy kidney and its lesions and graphic view of T2 decay].

Kidney diseases, healthy kidney tissue and adjacent organs like liver, musculature and fatty tissue were evaluated in respect to their T1-, T2-relaxation times and proton density values. In addition the results of an evaluation of T2-short, T2-long, Rho-short, Rho-long, which were calculated from the T2-relaxation times, are reported. The T2-times are very sensitive in demonstrating differences between the tissues, as significantly different values for healthy kidney tissue and hypernephromas could be found. Different values could be seen dependent on the calculation mode, whereby the calculations had been made from double echo and multiple echo sequences. The T1-relaxation times were less sensitive, differences could be also found between the calculations from the IR and SE mode. The values of T2-long and T2-short and the proton density values differed very much for the same organ in the examined groups of patients, therefore these additionally calculated values unlikely will help in the differential diagnosis of unknown kidney diseases.

Abscess↗
PubMed1986

[Demonstration of intra- and paracardiac space-occupying processes using magnetic resonance tomography].

Magnetic resonance tomography (in three planes) was performed on 21 patients in whom echocardiography, angiocardiography or a chest X-ray had indicated or was suspicious of intra- or paracardiac space-occupying lesions. MR imaging demonstrated bronchial carcinoma with aortic displacement in two (one of them also with vena cava occlusion); hypernephroma with displacement of the right atrium in one; paracardiac teratoma in two and lipoma in one; aortic aneurysm in two; atrial tumour in five; atrial thrombi in one; ventricular thrombi in four; and exclusion of intra-cardiac lesions in two. Thus the method distinguished between vascular and tumourous paracardiac space-occupying lesions and demonstrated origin and structural relationship of paracardiac tumours, especially to the great vessels. Size, shape and mobility of intracardiac tumours was also demonstrated. For both intra- and paracardiac space-occupying lesions there were the beginnings of structural differentiation.

Aortic Aneurysm↗
PubMed1986

Interleukin 2 receptors on cultured murine epidermal Langerhans cells.

Rat monoclonal antibodies 3C7 and 7D4 detect two distinct functional regions of the murine interleukin 2 (IL 2) receptor. When studying the emergence kinetics of IL 2 receptors in mixed epidermal cell (EC)-lymphocyte cultures by using 3C7 and 7D4 in an indirect immunofluorescence assay, we regularly encountered a distinctive membrane fluorescence not only on lymphocytes, but also on a subpopulation of cells exhibiting a dendritic morphology. Reasoning that these 3C7/7D4-reactive dendritic cells might represent a subpopulation of epidermal dendritic cells, we studied mouse EC for the presence of 3C7/7D4- reactive cells. Although 3C7/7D4 reactivity was never detected on freshly isolated EC or on epidermal sheets, a small number of 3C7/7D4+ cells was encountered after 24 to 48 hr of culture. These cells exhibited a dendritic shape, expressed Ia antigens, lacked Thy-1 antigens, and displayed the ultrastructural features of Langerhans cells (LC) with the notable exception of Birbeck granules. Although after 24 hr, only 20% of Ia+ EC were 3C7/7D4+, the vast majority of LC displayed 3C7/7D4 binding sites after 4 to 5 days of culture. Preincubation of cultured LC-enriched EC with recombinant human IL 2 prevented subsequent 3C7-but not 7D4-binding to these cells. Western blot analysis of 7D4-reactive material of detergent extracts from LC-enriched EC revealed three bands in the same m.w. range as reported for CTLL cells. These results demonstrate that cultured LC express IL 2 receptors and may bear important implications for a better understanding of growth regulation, differentiation, and immunologic functions of LC.

Animals↗
PubMed1986

Hypertriglyceridemia and carbohydrate intolerance: interrelations and therapeutic implications.

Atherosclerosis, the most frequent complication of diabetes, could be the result of hyperlipidemia, among other factors. Mounting evidence suggests that reducing the concentration of triglyceride-rich lipoprotein, which influences the production of the possibly atherogenic intermediate density lipoprotein (IDL), might diminish the circulating level of potentially atherogenic lipoproteins. Hypertriglyceridemia, even in the absence of obesity, is associated with insulin resistance. To compensate, pancreatic B cells respond to glucose challenge by producing hyperinsulinemia. If the B cells cannot respond adequately, carbohydrate intolerance ensues. Insulin-treated diabetics may also become hyperinsulinemic because routine insulin injection may not reflect physiologic need and because the insulin is administered peripherally rather than portally. Hyperinsulinemia increases the production of circulating triglyceride. It appears to do this in rats by causing the production of more triglyceride-rich lipoprotein particles rather than by increasing the triglyceride content of each particle. Further, at least in rats, the insulin-induced increase in triglyceride production requires the presence of supplementary dietary fructose. Hyperinsulinemia also increases the activity of adipose tissue lipoprotein lipase and the degradation of very low density lipoprotein (VLDL). The concentration of VLDL depends on balance of production and degradation. Accelerated VLDL degradation leads to an increase in IDL production. Because there is mounting evidence that IDL may be atherogenic, this cycle could accelerate atherogenesis. As such, it is reasonable to postulate that reducing the concentration of triglyceride-rich lipoproteins would break this cycle and would diminish the circulating level of potentially atherogenic lipoproteins.

Arteriosclerosis↗
PubMed1986

Portal v peripheral hyperinsulinemia and very low density lipoprotein triglyceride kinetics.

The effect of subcutaneously delivered insulin on the kinetics of rat plasma triglycerides was compared to that of intraperitoneally delivered insulin. The former route delivered insulin primarily extrahepatically and the latter, intraportally. In comparison to the intraperitoneally delivered insulin, the subcutaneously delivered insulin was associated with a higher peripheral serum insulin, lower serum glucose, lower serum FFA, lower serum triglycerides, and similar rate of triglyceride secretion. The activity of adipose tissue lipoprotein lipase was directly related to the serum insulin concentration. The pattern of serum triglycerides and lipoprotein lipase in the rats receiving subcutaneous insulin suggested that their rate of triglyceride removal exceeded that seen in the rats receiving intraperitoneal insulin. These observations indicate that the route of insulin delivery can influence the balance between the hepatic and extrahepatic effects of insulin on triglyceride kinetics.

Adipose Tissue↗
PubMed1986

Metabolism of the apolipoprotein B-containing lipoproteins.

This chapter was designed to describe the approaches one can take to study the metabolism of the apoB-containing particles in vivo. The focus has been to blend (1) what is the current tracer kinetics analysis methodology and (2) what are the current experimental protocols being used into a total picture so that the experimentalist wishing to perform such studies may have a better perspective of the strong points and pitfalls of this important experimental tool. Hence, these points have been summarized from the point of view of what caveats are associated with each methodology. Recognition of these is essential to avoid reaching potentially erroneous conclusions. More important, attention has been focused on the realization that certain methodologies can be chosen depending upon what questions are being asked. Finally, areas where future development is needed in order to proceed to the next level of understanding are pointed out in the context of using tracer kinetic analysis as an integral part of a total experimental design.

Animals↗
PubMed1986

Tricyclic epines. Novel (E)- and (Z)-11H-dibenz[b,e]azepines as potential central nervous system agents. Variation of the basic side chain.

The synthesis and pharmacological activity of new (E),(Z)-[6-(alkylamino)-11H-dibenz[b,e]azepin-11- ylidene]acetonitriles 12-45 and (E),(Z)-[6-(aminoalkoxy)-11H-dibenz[b,e]azepin-11-ylidene] acetonitriles 46-51 are described. The introduction of the cyanomethylene group into the 11-position of the 11H-dibenz[b,e]azepine framework has been carried out by a Wittig-Horner reaction under mild conditions. The (E),(Z) isomers were separated by fractional crystallization, assignment being achieved by X-ray analysis. A number of (E),(Z)-[6-(alkylamino)-11H-dibenz-[b,e]azepin-11-ylidene] acetonitriles (12, 14, 16, 20) show potent neuroleptic activity (2-7 times that of clozapine) in animal tests. The screening included tests for sedative and anticholinergic activity in mice, apomorphine and tryptamine antagonism in rats, and muscle-relaxing activity in rabbits. The divergence in the activity profile in the case of the separated (E),(Z) isomers has been observed as an interesting new aspect: the (Z) isomers show a significantly higher sedative and muscle-relaxant activity, whereas the (E) isomers possess a higher anticholinergic efficacy and somewhat greater apomorphine antagonism. Broad changes in the basic side chain were made in order to investigate structure-activity relationships. The important geometrical parameters for the molecules, obtained by X-ray analysis, were compared with the corresponding features in dopamine agonists and antagonists.

Animals↗
PubMed1986

[Analysis of the NMR signal for biological information in spinal diagnosis].

Discs of 23 patients and volunteers were examined for the purpose of obtaining T1 and T2-relaxation times. First of all, the signal characteristics of the surface coil were evaluated. The relaxation times of 100 discs were then measured by using standard spin echo sequences. There was a correlation between age and T2-values for healthy discs (R = -0.744). This was not found in case of degenerated discs. The mean value of T1 for healthy discs was found to be 825 ms. The results show a possibility of using relaxation measurements in routine diagnosis for the early identification of disc degeneration.

Adult↗