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Biomedical subjects

M Wong

Publications and source records attributed to M Wong.

At least 307 records · Page 17Linked to original sources
PubMed1985

Expression of murine 21-hydroxylase in mouse adrenal glands and in transfected Y1 adrenocortical tumor cells.

The S region of the murine major histocompatibility complex contains two structurally related genes (21-OHase A and 21-OHase B) that encode 21-hydroxylase (21-OHase), an enzyme essential for the synthesis of adrenal steroids. Expression of these two genes has been analyzed by using oligonucleotide probes specific for the 21-OHase A and B genes and by DNA-mediated gene transfer. Hybridization of the oligonucleotides to blots of BALB/c adrenal RNA demonstrated that all 21-OHase mRNA is derived from the 21-OHase A gene. Cosmids bearing either the 21-OHase A or B gene were introduced into Y1 adrenocortical tumor cells by cotransfection with pSV2-neo. Cells transfected with the 21-OHase A gene expressed 21-OHase as determined by steroid metabolism and by RNA blot hybridization; 21-OHase transcripts were not detected in parent Y1 cells or in cells transfected with the 21-OHase B gene. Treatment of 21-OHase A transfectants with adrenocorticotropin increased 21-OHase mRNA levels by up to 10-fold, thus mimicking the observed effect of this hormone on 21-OHase levels in primary adrenal cultures. The regulated expression of the 21-OHase A gene in transfected Y1 cells should provide a useful system for the investigation of factors controlling the adrenal-specific regulation of 21-OHase activity.

Adrenal Cortex Neoplasms↗
PubMed1985

Improved graft patency in patients treated with platelet-inhibiting therapy after coronary bypass surgery.

One hundred forty-seven consecutive coronary bypass patients were enrolled in a randomized, double-blind, risk-stratified, placebo-controlled prospective trial evaluating the effect on graft patency of 325 mg tid aspirin (ASA) plus 75 mg tid dipyridamole (DP) or ASA alone. One hundred twenty-seven patients (399 total grafts) underwent surgery, initiation of drug therapy 67 +/- 27 (SD) hr postoperatively, five clinic visits, and repeat angiography at 1 year. A logistic regression statistical model was used to determine the effects of 28 different measured variables on graft patency and to adjust for these effects in determining the relationship between antiplatelet therapy and graft occlusion. No patient-specific variable contributed significantly to the prediction of occlusion in either the placebo or the treated group. Six graft-specific variables (arterial diameter, severity of stenosis, graft flow, reactive hyperemia, presence or absence of collaterals, and graft type) did contribute and were included in the model. Twenty-one percent of placebo-treated grafts became occluded. Compared with placebo, the relative risk of graft occlusion with ASA was 0.47 (p = .04); with ASA + DP, it was 0.50 (p = .04). This benefit was principally due to reduction of occlusion in the most common and presumably most important groups of grafts, those in which flow exceeded 40 ml/min, or supplying arteries having luminal diameters greater than 1.5 mm. Grafts lacking reactive hyperemia had a 32% occlusion frequency in placebo-treated patients; relative risk of their occlusion averaged 0.26 (p less than .01) with platelet-inhibiting therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Glycolipid transfer protein from bovine brain.

Glycolipid transfer protein from bovine brain has been purified partially by ammonium sulfate precipitation, CM-52 ion-exchange, and Sephadex G-75 column chromatography. Both pyrene-labeled and tritium-labeled glucocerebrosides have been used to study the kinetics of protein-mediated transfer between donor and acceptor vesicles. Protein accelerates glucocerebroside transfer but does not accelerate phospholipid transfer. In colyophilized small sonicated vesicles (10% glucocerebroside, 90% 1-palmitoyl-2-oleoyl-phosphatidylcholine) about two-thirds of the glycolipid is transferred in 2 h and the remaining one-third does not transfer (up to 5 h). For donor and acceptor vesicles made of dipalmitoylphosphatidylcholine or 1-palmitoyl-2-oleoyl-phosphatidylcholine, glucocerebroside (10% in donors) is transferred rapidly only when both the donor and acceptor matrix phospholipids are in the liquid-crystalline state. If either donor or acceptor vesicles are in the gel state, transfer protein mediated transfer is much reduced. The amount of transfer protein bound specifically to glucocerebroside-containing vesicles is nearly equal above and below the matrix phospholipid phase transition temperature. Bound protein transfers glucocerebroside upon addition of acceptor vesicles.

Animals↗
PubMed1984

A relationship between nuclear poly(adenosine diphosphate ribosylation) and acetylation posttranslational modifications. 2. Histone studies.

In the accompanying paper [Malik, N., & Smulson, M. (1984) Biochemistry (preceding paper in this issue)], we report that certain acetylated domains of chromatin were selectively retained by an anti-poly(ADP-Rib) antibody column. In this paper, we describe investigations of this phenomenon at the molecular level of protein interactions. We observed that the majority of endogenously hyperacetylated histones have a high affinity toward the polymer antibody column. It is speculated that these proteins were bound to the column via endogenous poly(adenosine diphosphate ribose) [poly(ADP-Rib)] since the binding was reversed upon treatment of the histones with alkali prior to immunofractionation. In order to analyze the distribution of acetate and poly(ADP-Rib) on histone proteins, [3H]acetylated nuclei were incubated in vitro with [32P]NAD. Acetate was incorporated mainly into H3 and H4 while H1 was the major acceptor protein for poly(ADP-Rib). These results suggest that a correlation may exist in vivo between the two posttranslational modification processes and that identical histone molecules may be accessible to both modifications.

Acetylation↗
PubMed1984

The mechanism of histone H1 cross-linking by poly(ADP-ribosylation). Reconstitution with peptide domains.

One of the major products of the poly(ADP-Rib) polymerase reaction is the H1 dimer, formed by cross-linking two H1 molecules with a 15-unit poly(ADP-Rib) chain. In the present study we have attempted to characterize those regions of H1 molecules which participate in cross-linking, and in particular, to determine whether the reaction involves two NH2-terminal domains, two COOH-terminal domains, or a combination of these two. When we used reconstituted chromatin, formed by the addition of various H1 peptides to H1-depleted chromatin, we observed poly(ADP-ribosylation) in those complexes containing fragments of the NG-H1 domain (i.e. NH2-terminal tail plus the globular (G) region). Furthermore, with this material, increasing NAD concentration and incubation time led to a progressive elongation of poly(ADP-Rib) on the peptide approaching a chain length of 11-12 units. Reconstituted chromatin that contained other H1-derived peptides, such as C-H1 and G-H1 (i.e. only carboxyl or only globular domains respectively), were not poly(ADP-ribosylated). CG-H1 was noted to be a substrate in the reconstituted system. However, in contrast to NG-H1, where extensive chain elongation was observed, only very short chain, probably mono(ADP-ribosylation) occurred on this H1 peptide. In a complementary approach, the H1 dimer complex or its precursors were cleaved with N-bromosuccinimide, and peptide fragments isolated. This analysis confirmed that both the NH2- and COOH-terminal domains of H1 are poly(ADP-ribosylated) and that elongation of the ADP-ribose chain occurred primarily at the NH2 terminus during H1 dimer synthesis.

Amino Acid Sequence↗
PubMed1984

Insulin resistance with acanthosis nigricans and acral hypertrophy.

Two patients are described with obesity, acanthosis nigricans, acral hypertrophy, basal hyperinsulinism and exaggerated insulin responses to oral glucose. One patient, a diabetic female showed features of virilisation due to polycystic ovarian disease and underwent gonadectomy with some resolution of her androgenisation and acanthosis nigricans. Binding of labelled insulin to erythrocytes was significantly decreased in both patients compared with normal or obese control subjects. In contrast, the receptor concentration in adipose tissue obtained from the patient undergoing gonadectomy was higher than seen in obese control subjects. Thus, somatic growth may be stimulated by insulin in some tissues in these hyperinsulinaemic patients due to relative preservation of receptor numbers.

Acanthosis Nigricans↗
PubMed1984

Schizophyllan (SPG)-treated macrophages and anti-tumor activities against syngeneic and allogeneic tumor cells. I. Characteristics of SPG-treated macrophages.

We tested anti-tumor activities of macrophages treated with a neutral polysaccharide, schizophyllan (SPG), against syngeneic and allogeneic tumor cell lines. SPG was a macrophage stimulant which was not mitogenic to lymphocytes. That made a sharp contrast with the data that Corynebacterium parvum, BCG, and muramyl dipeptide (MDF) were macrophage stimulants which had lymphocyte-activating properties. Treatment of SPG-treated PEC with Thy12 monoclonal antibody and guinea pig complement did not affect the capabilities of tumor-cell-growth suppression by the treated PEC. Thus, the effector cells were peritoneal adherent cells (macrophages morphologically) and effector-to-target contact seemed to be necessary for effective tumor-cell-growth inhibition, although contradictory data exist for this. Murine peritoneal adherent cells harvested 4 days after a single IP injection of SPG at a dose of 100 mg/kg body weight of mouse showed the most prominent cytostatic and cytotoxic activities against syngeneic and allogeneic tumor cells. The distribution of anti-tumor activity in macrophages of various sizes followed the same pattern as macrophages treated with C. Parvum, i.e., larger macrophages showed more remarkable anti-tumor activity. Crude nonadherent peritoneal cells incubated with SPG at a concentration of 10 micrograms/ml, 100 micrograms/ml, or 1 mg/ml did not secrete lymphokine that rendered macrophages cytotoxic, while ConA-treated nonadherent cells did so. Furthermore, spleen cells treated with SPG in vivo did not secrete macrophage-activating lymphokine in the presence of SPG. On the other hand, addition of 1 mg/ml of SPG-treated peritoneal adherent cells and bone-marrow-derived macrophages in vitro rendered them cytotoxic to a moderate degree. This implies that SPG may activate macrophages directly, allowing them to become cytotoxic in the peritoneal cavity. Lastly, SPG could induce production of II-1-like factor to a moderate degree. SPG, whose molecular structure is well elucidated, will provide us with a strong tool to analyze the mechanism of macrophage activation both in vitro and in vivo.

Animals↗
PubMed1984

Multiple assessment of coping strategies used by volunteer blood donors: implications for preparatory training.

The coping strategies used by volunteer blood donors were assessed in two studies. A general trait measure and a specific process measure of coping were administered in both studies. A state measure of coping was added in the second study. The relationships among these measures and their relationships with anxiety measures and demographic variables [e.g., sex and prior donation frequency] were examined. Moderate correspondence was found among the coping indices, but the process measure was most predictive of anxiety ratings. An avoidant coping strategy appeared to be most effective in terms of managing the stress of blood donation. Implications of the results for the conceptualization and assessment of coping are noted, and suggestions are made regarding factors which may affect the preparation of patients for stressful medical or dental treatment.

Adult↗
PubMed1984

Collagen in the egg shell membranes of the hen.

Collagen-like proteins have been found in the egg shell membranes of the hen. Materials similar to types I and V collagens were detected in each of the two layers of this membrane, the thick outer membrane and the thin inner membrane. Collagen was extracted by acid-pepsin digestion and isolated by differential salt precipitation. Identification of type-specific collagen-like material was established by coelectrophoresis on SDS-polyacrylamide gels using known collagen standards. These bands were susceptible to digestion by bacterial collagenase. From differential staining of the gels it was estimated that the ratio of collagen types I:V was approximately 100:1. Further confirmation of these biochemical results was obtained with immunofluorescence microscopy using type-specific antisera against chicken types I and V collagen with the indirect sandwich technique. Both the inner and outer shell membranes contained the two types of collagen. Within each membrane, the large, coarse 2.5-micron fibers contained predominantly type I collagen-like material, while type V collagen was mainly associated with the delicate narrower fibers of approximately 0.6-micron diameter. These tended to be concentrated in the inner membrane. At the electron microscopic level, both types of fibers were coated with glycoproteins that stained positively with ruthenium red. The deposition of these collagen-like substances by the hen oviduct on to the surface of the developing egg is an additional example of interstitial-type collagen synthesis and secretion by epithelial rather than by mesenchymal cells.

Animals↗
PubMed1984

Neon-20 depth-dose relations in water.

The dose from heavy ion beams has been calculated using a one-dimensional transport theory and evaluated for 670 MeV/ amu 20Ne beams in water. The result is presented so as to be applicable to arbitrary ions for which the necessary interaction data are known. The present evaluation is based on the Silberberg - Tsao fragmentation parameters augmented with light fragment production from intranuclear cascades, recently calculated nuclear absorption cross sections, and evaluated stopping power data. Comparison with recent experimental data obtained at the Lawrence Berkeley Laboratory reveals the need for more accurate fragmentation data.

Ions↗
PubMed1984

A comparison of the stimulatory activities of lymphoid dendritic cells and macrophages in T proliferative responses to various antigens.

The identities of murine accessory cells and the mechanism by which they process antigen and stimulate T cell proliferation have been examined with cell separation techniques and specific agents to block antigen catabolism. Using preparations of splenic dendritic cells (DC) and macrophages (M phi) with minimal cross-contamination, we found that only DC could induce syngeneic mixed leukocyte reaction (MLR), whereas both DC and M phi could initiate allogeneic MLR. This observation may have significant implications for syngeneic MLR as a manifestation of self Ia recognition, and for the cell type that defines self Ia during ontogeny. DC and M phi could present soluble antigens such as purified protein derivative of tuberculin (PPD) and Salmonella flagellin about equally well to antigen-specific T cell lines. M phi, however, were much more effective than the non-phagocytic DC at inducing T cell proliferation to whole Corynebacterium parvum organisms. These differences could not be attributed to differences in antigen uptake. The results suggest that the bacteria must be ingested and processed by phagocytes before T cell activation. Using the lysosomotropic agent chloroquine to inhibit antigen catabolism in accessory cells, we found that the presentation of large antigens by M phi and DC was abolished by chloroquine treatment, whereas T cell activation by antigens (such as PPD or integral membrane Ia for MLR) that apparently required no processing was relatively insensitive to chloroquine. Thus, in addition to differences between cells, discrete functions within each cell type can also be distinguished.

Animals↗
PubMed1984

Detection of Goodpasture antigen in fractions prepared from collagenase digests of human glomerular basement membrane.

Preparations of human glomerular basement membrane (GBM) were digested with collagenase, and a Goodpasture (GP) antigen rich pool from gel filtration column runs was identified by antibody inhibition radioimmunoassay. The components of the GP antigen pool were separated on polyacrylamide gels, and transferred to nitrocellulose sheets by the 'western' blotting technique. The blots were separately reacted with thirteen GP sera as primary antibody, followed by peroxidase labelled goat anti-human IgG and revealed 45-50K (two bands) and 25-28K (one-three bands) components. No corresponding reactivity was observed using convalescent GP sera or other control sera (normal human serum, rapidly progressive glomerulonephritis with or without pulmonary haemorrhage, and lupus erythematosus) as primary antibody.

Amino Acids↗
PubMed1983

Echocardiographic evaluation of normal and prolapsed tricuspid valve leaflets.

The tricuspid valve was examined by 2-dimensional (2-D) echocardiography in 14 patients with tricuspid valve prolapse (TVP) and in 16 normal subjects. Individual leaflets were identified anatomically and for frequency of prolapse. Maximal and minimal anular sizes were measured. Multiple tomograms of the tricuspid anulus were recorded at 30 degrees intervals around the tricuspid anulus with the transducer placed at the right ventricular apex. Anuli were reconstructed from the 6 planes and corrected for body surface area. Three leaflets of the tricuspid valve could be anatomically identified in all patients. Prolapse of all 3 leaflets was observed in 6 patients, 2 leaflets in 5 and 1 in 3. Frequency of individual leaflet prolapse was 93% for the septal cusp, 86% for the anterior and 43% for the posterior. Maximal anular circumference and area in TVP were 7.9 +/- 0.6 and 8.9 +/- 1.3 cm2/m2, respectively--significantly larger than values in normal subjects (6.4 +/- 0.5 cm/m2 and 6.1 +/- 0.9 cm2/m2, respectively) (p less than 0.001). Percent reductions in circumference and area in TVP were 14 +/- 3 and 25 +/- 5%, respectively--significantly smaller values than in normal subjects (19 +/- 4 and 33 +/- 4%, respectively). Tricuspid regurgitation (TR) was detected by contrast echocardiography in 7 of 14 patients with TVP. The severity of TR appeared to be minimal in 6 of the 7 patients, and was not associated with an increase in anular size. Thus, TVP is associated with anular dilatation irrespective of associated TR, probably as a primary pathologic characteristic.

Adult↗
PubMed1983

Relationship between histone H1 poly(adenosine diphosphate ribosylation) and histone H1 phosphorylation using anti-poly(adenosine diphosphate ribose) antibody.

The chromatin-associated enzyme poly(ADP-Rib) polymerase catalyzes the posttranslational modification of histones. Antibody to poly(ADP-Rib) has been coupled to Sepharose, and the resultant immunoadsorbent was used to fractionate, specifically, histone H1 subpopulations undergoing this nuclear protein modification. When this method of separation was used, it was additionally observed that poly-(ADP-ribosylated) H1 species were highly accessible to in vitro phosphorylation by nuclear protein kinase. Phosphorylated H1 molecules were retained by the anti-poly(ADP-Rib)-Sepharose column due to the presence of endogenous poly-(ADP-Rib) components. Degradation of the latter moieties on phosphorylated H1 reversed their adsorption to the column.

Adenosine Triphosphate↗
PubMed1983

Immunological evidence for the in vivo occurrence of a crosslinked complex of poly(ADP-ribosylated) histone H1.

The poly(ADP-ribosylation) of histones, which occurs within a limited and functionally specific domain of chromatin, is a novel post-translational modification. However, in the past it has been difficult to study this process in living cells because the substrate of the reaction (NAD) does not permeate the plasma membrane. In the current study, antibodies specific for histone H1 and poly(ADP-ribose) were used to study the occurrence of poly(ADP-ribose)+ species of H1 in vivo. Perchloric acid-extracted proteins from synchronously growing HeLa cells were fractionated by electrophoresis and transferred to nitrocellulose, and the transferred moieties were allowed to react with the specific antibodies and then with 125I-labeled protein A. The results conclusively demonstrate the natural occurrence of poly(ADP-ribose)-crosslinked complexes of histone H1 (i.e., H1 dimer), at the S/G2 phase transition of the cell cycle.

Cell Cycle↗