A new frameshift mutation 460delG in exon 4 of the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
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Adult↗
Biomedical subjects
M Yang
Publications and source records attributed to M Yang.
TPN-induced fulminant beriberi: a report on our experience and a review of the literature.
Fulminant beriberi, once considered a rare disease, is now being encountered more frequently, yet little is known about its clinical features. This study was undertaken to determine the clinical features of total parenteral nutrition (TPN)-induced fulminant beriberi by reviewing the clinical data on 10 of our own patients who developed this complication, and 33 cases documented in the literature. TPN-induced fulminant beriberi became evident 4-40 days after the initiation of TPN, and was more likely to develop in patients with malignancies, ulcerative colitis, and short bowel syndrome, as well as in those receiving chemotherapy. Although the patients manifested various symptoms, very few developed the classical signs of beriberi or the constant findings seen in alcoholic patients. The severity of metabolic acidosis was extremely high and refractory to bicarbonate administration, but it responded quickly to intravenous (i.v.) thiamine. Thus, rapid i.v. administration of at least 100 mg of thiamine is imperative, and the patient must be transferred to the intensive care unit when TPN-induced fulminant beriberi develops.
Acidosis↗
Mechanics of ventricular torsion.
Recent research suggests that left ventricular torsion is an important indicator of cardiac function. We used two theoretical models to study the mechanics of this phenomenon: a compressible cylinder and an incompressible ellipsoid of revolution. The analyses of both models account for large- strain passive and active material behavior, with a muscle fiber angle that varies linearly from endocardium to epicardium. Relative to the end- diastolic configuration, the predicted torsion exhibits several experimentally observed features, including a peak near end systole, rapid untwisting during isovolumic relaxation, and increased twist near the apex. The magnitude of the twist is sensitive to the fiber architecture, the ventricular geometry, and the compressibility and contractility of the myocardium. In particular, the model predicts that the systolic twist increases with increasing compressibility, contractility, and wall thickness, while it decreases with increasing cavity volume. The peak twist approximately doubles (from about 0.02 to 0.04 rad cm(-1)) with a doubling of myocardial compressibility or with a change in the endocardial/epicardial muscle fiber angles from 90/ -90 degrees to 60/ -60 degrees. The twist is less sensitive to changes in contractility and ventricular geometry. These findings provide a basis for interpreting measurements of ventricular torsion in the clinical setting.
Animals↗
Immunologic mechanisms in mosquito allergy: correlation of skin reactions with specific IgE and IgG antibodies and lymphocyte proliferation response to mosquito antigens.
BACKGROUND: Allergic reactions to mosquito bites are a common problem. Although IgE-mediated hypersensitivity has been reported, other immunologic mechanisms may be involved. OBJECTIVES: To study the relationship between skin bite reactions and immunologic parameters. METHODS: Forty-one subjects were experimentally exposed to mosquito (Aedes vexans) bites. Immediate and delayed skin reactions were traced at 20 minutes and 24 hours, respectively, after the bites. Sera were analyzed for mosquito salivary gland-specific IgE (mosquito-IgE) and IgG (mosquito-IgG) by ELISA. Lymphocyte proliferation assays with mosquito extract were also performed. RESULTS: One of 41 subjects had only a delayed skin reaction to the bite, 23 had both immediate and delayed reactions, 6 had only immediate reactions, and 11 had no reaction. The mean mosquito-IgE and -IgG concentrations were higher in the subjects with immediate reactions than in those without immediate reactions (P < .007). The mean lymphocyte proliferation stimulation index was higher in the subjects with delayed reactions than in those without delayed reactions (P < .015). Further, both mosquito-IgE and -IgG levels correlated with skin immediate and delayed reactions (P < .04), while lymphocyte proliferation indices only correlated with skin delayed reactions (P < .006). Inverse correlations were found between the size of skin reactions and the number of years lived in Canada (P < .04), but not with age. CONCLUSION: These results indicate that IgE-, lymphocyte- and, probably, local IgG immune-complex-mediated hypersensitivities are involved in mosquito allergy. Naturally acquired desensitization to mosquito bites occurs during long-term exposure.
Adult↗
Adriamycin stimulates proliferation of human lymphoblastic leukaemic cells via a mechanism of hydrogen peroxide (H2O2) production.
It is becoming clear that adriamycin cytotoxicity may be mediated by semiquinone-free radicals derived from the drug itself and reactive oxygen species (ROS). Recent evidence supports the concept that low concentrations of ROS are able to stimulate cell proliferation, and, based on the observation that subtoxic concentrations of adriamycin can also induce cell proliferation, we hypothesize that low concentrations of adriamycin stimulate cell proliferation by a ROS generation mechanism. We have employed spin-trapping and electron spin resonance (ESR) spectroscopy to investigate the nature of the adriamycin-generated ROS. The spin trap 3,5-dibromo-4-nitrosobenzenesulphonate (DBNBS), which is oxidized in the presence of H2O2 and peroxidase enzymes, was used to produce a characteristic three-line spectrum, and it was found that an identical spectrum was produced by human lymphoblastic leukaemic cells (CCRF-CEM cells) after exposure to adriamycin. We tested our hypothesis further by exposing CCRF-CEM cells to subtoxic concentrations of adriamycin (10(-8), 10(-9) and 10(-10) M) and low concentrations of H2O2 (10(-8), 10(-9) and 10(-10) M) and subsequently monitored cell proliferation. We found that low concentrations of both adriamycin and H2O2 significantly stimulate CCRF-CEM cell proliferation. We therefore conclude that subtoxic concentrations of adriamycin are likely to induce cell proliferation via an H2O2 mediated mechanism.
Cell Division↗
Multiple B- and T-cell epitopes on a major allergen of Kentucky Bluegrass pollen.
The B- and T-cell epitopes of a recombinant grass allergen, rKBG60, were delineated using a set of overlapping synthetic peptides. Direct binding by enzyme-linked immunosorbent assay (ELISA) utilizing serum pools led to the identification of 13 murine immunoglobulin-, and nine to 13 human IgG- and five to seven human IgE-reactive overlapping peptides. Of the peptides which bound to human IgE antibodies, all but three peptides bound to human and/or murine IgG antibodies. Furthermore, eight out of 12 synthetic peptides induced antigen-specific antibodies in mice, suggesting that these peptides contained epitopes that recognized and/or induced T cells. These results, in conjunction with cross-recognition of different peptides at the C-terminus of rKBG60 by antibodies to neighbouring or non-overlapping peptides suggest that the C-terminus of this antigen represents a dominant antigenic and allergenic site. Peripheral blood mononuclear cell (PBMC) proliferation studies using these synthetic peptides for 13 grass allergic individuals indicated that seven potential human T-cell epitopes exist on this allergen. Taken together, the results demonstrate that multiple B- and T-cell epitopes exist on this major group of grass allergens, the majority of which are localized at the C-terminus of this antigen.
Allergens↗
Serotonin stimulates megakaryocytopoiesis via the 5-HT2 receptor.
It is known that platelet alpha-granule constituents including platelet-derived growth factor (PDGF), platelet factor 4 (PF4) and transforming growth factor-beta (TGF-beta) can affect megakaryocytopoiesis. Serotonin, a platelet dense granule constituent has been shown to have a mitogenic effect on fibroblasts and smooth muscle cells but whether it has the same effect on megakaryocytes remains unclear. In this study, we investigated the effect of serotonin on megakaryocytopoiesis and the possible mechanism of its effect using the mouse plasma clot culture method. The results show that: (a) serotonin significantly stimulates megakaryocyte colony formation with maximum stimulation at 100 nM; (b) enhanced action is found between serotonin and interleukin-3 (IL-3), interleukin-6 (IL-6), granulocyte macrophage-colony stimulating factor (GM-CSF), erythropoietin (EPO) and PDGF; (c) ketanserin, a 5-HT2 receptor antagonist, blocks the mitogenic effect of serotonin on megakaryocytopoiesis; and (d) Meg-01 cells (a megakaryocyte cell line) express 5-HT2 receptors. This study demonstrates that serotonin has a mitogenic effect on megakaryocytopoiesis and this effect may be mediated via the 5-HT2 receptor which is known to be coupled to G protein. It is suggested that serotonin may also be involved in the feedback control of megakaryocytopoiesis.
Animals↗
The bglX gene located at 47.8 min on the Escherichia coli chromosome encodes a periplasmic beta-glucosidase.
A new Escherichia coli gene, bgIX, encoding a beta-D-glucosidase (EC 3.2.1.21) has been characterized. The bgIX gene is located adjacent to the dld gene at 47.8 min or 2225 kb on the E. coli chromosome. The sequence of a 2.6 kb DNA fragment from this region revealed a large open reading frame encoding a protein of 765 amino acids. The BgIX protein was purified from the periplasm, and amino-terminal sequencing suggests that the mature protein is derived from cleavage of a 20 residue signal peptide. A search of the sequence databases revealed that BgIX is a member of a large family of beta-glucosidases from a variety of bacteria and fungi, and the plant Arabidopsis thaliana. It differs from the other four E. coli phospho-beta-glucosidases in sequence and in its periplasmic rather than cytoplasmic location. The BgIX enzyme has a Km of 18 +/- 1 mM and a Vmax of 3 +/- 0.7 mumol min-1 for the colorimetric substrate o-nitrophenyl beta-D-glucopyranoside.
Amino Acid Sequence↗
Suppressing effects of 6-(2,5-dichlorophenyl)-2,4-diamino-1,3,5-triazine and related synthetic compounds on azoxymethane-induced aberrant crypt foci in rat colon.
The modifying effects of dietary administration of 6-(2,5-dichlorophenyl)-2,4-diamino-1,3,5-triazine and 5 related compounds on the occurrence of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) were investigated in rats. Male F344 rats were given s.c. injections of AOM (15 mg/kg body weight) once a week for 3 weeks to induce ACF. They also received the diet containing 200 ppm test compound for 5 weeks, starting one week before the first dosing of AOM. At the termination of experiment, all of the compounds had caused a significant reduction in ACF frequency, which might be associated with suppression of the expression of proliferation biomarkers. The apoptotic index in the colonic mucosal epithelium of rats killed at 6 h after the first AOM exposure revealed no blocking activity of the compounds.
Animals↗
Immunocytochemical study of the NMDA receptor in the visual cortex of strabismic cat.
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Animals↗
Expression of the human cell surface glycoconjugates Lewis x and Lewis y by Helicobacter pylori isolates is related to cagA status.
Monoclonal antibodies were used in an enzyme-linked immunosorbent assay for the detection of human Lewis immunodeterminants in the lipopolysaccharide of Helicobacter pylori. In 94 H. pylori isolates, expression of Lewis(x) (Le(x)) and Le(y) was a stable phenotypic marker independent of the growth medium and cell age; 46 (49%) of the isolates expressed both and 34 (36%) of the isolates expressed either Le(x) or Le(y); 14 (15%) were negative for both determinants. Twelve (13%) isolates expressed Le(b), 3 (3%) expressed Le(a), and 2 (2%) expressed sialyl-Le(x). H. pylori isolates positive for both Le(x) and Le(y) were predominantly cagA+ (P < 0.001) and possessed the s1 signal sequence (P < 0.05) and the m1 midregion type (P = 0.033) of vacA. Isogenic mutants of H. pylori CPY3401 were created by interruption of the cagA, picB, or ureA gene. The cagA-ablated strain (but not the picB- and ureA-ablated mutant strains) had significantly (P < 0.01) diminished expression of Le(y) compared with that of the wild-type strain; for all four strains, expression of Le(x) was similar. In conclusion, 89% of H. pylori isolates express Le determinants in their lipopolysaccharide, mimicking human cell surface glycoconjugates. Strong expression of Le(x) and Le(y) by cagA+ isolates could counterbalance their enhanced proinflammatory activities and thereby facilitate persistence.
Antibodies, Monoclonal↗
Cross-reactivity and molecular mass of the epsilon chains of the IgE antibodies in dogs, humans, rats, and mice.
We report the cross-reactivities and comparative molecular masses of the IgE epsilon chains in humans, rats, mice, and dogs. Monoclonal human, rat, and mouse IgE, and our purified polyclonal dog IgE were used in the study. IgE of the 4 species, separated by SDS-PAGE, were analyzed by immunoblotting with polyclonal and monoclonal antihuman IgE, polyclonal and monoclonal antimouse IgE, monoclonal antirat IgE, and polyclonal antidog IgE antibodies. The polyclonal antihuman and polyclonal antimouse IgE cross-reacted with the IgE of the other 3 species, while their monoclonal forms cross-reacted with dog IgE only. Polyclonal antidog IgE cross-reacted with human and mouse IgE, while the monoclonal antirat IgE did not cross-react with any other species. "Reverse' passive cutaneous anaphylaxis in ragweed-sensitized dogs revealed that polyclonal antihuman and polyclonal antimouse IgE were able to elicit positive skin responses, and monoclonal antihuman, antirat, and antimouse IgE antibodies were not. The molecular masses of the epsilon chains were 77 kDa for mice, 75 kDa for rats and dogs, and 70 kDa for humans.
Animals↗
Host genetic and adjuvant factors influence epitope specificity to a major recombinant grass allergen.
The role of host genetic and adjuvant factors in the induction of immune responses to a major recombinant Kentucky bluegrass allergen was examined utilizing five strains of mice and two different adjuvants. Analysis of the recombinant allergen-specific antibodies induced in these strains indicated that the antibodies of various isotypes were differentially regulated. In terms of IgE antibody response, BDF1 and DBA/2 were characterized as high responder, whereas BALB/C, CBA/J and C57BL/6 were intermediate and SJL was a low responder. In different strains, both dextran sulfate (DS) and complete Freund's adjuvant (CFA), as adjuvants, induced recombinant allergen-specific IgE antibodies of similar titer, however, CFA induced higher IgG2a and lower IgM antibodies compared to DS. Further, analysis of T cell proliferative responses of the splenocytes of different strains demonstrated that these strains varied also in their capacity to respond to synthetic peptides. Furthermore, utilizing a panel of synthetic peptides corresponding to the recombinant allergen, we demonstrated that the antibodies induced by the recombinant allergen with CFA in different strains vary with respect to their epitope specificity. In the BDF1 strain, compared to DS, CFA as adjuvant induced recombinant allergen-specific antibodies of additional peptide specificity. Taken together, these results suggest that both host genetic background and adjuvants govern the fine specificity of antibodies produced against this recombinant Kentucky bluegrass allergen.
Adjuvants, Immunologic↗
Wortmannin inhibits the production of reactive oxygen and nitrogen intermediates and the killing of the Saccharomyces cerevisiae by isolated chicken macrophages.
The direct effects of wortmannin (0 to 1280 nM) on several functions in cultured macrophages isolated from Sephadex-elicited Leghorn chicken peritonea were studied. Under concentrations not affecting cell viability, wortmannin, as low as 5 nM, inhibited lipopolysaccharide (LPS)-induced nitric oxide production (P < 0.01). However, wortmannin (as high as 1280 nM) exposure 5 hours post LPS induction had no effect on nitric oxide production in macrophages, indicating a blockade of LPS-induction of a signaling pathway related to nitric oxide formation. Phorbol myristate acetate (PMA)-induced superoxide production was only inhibited (P < 0.001) by concurrent exposure to 1280 nM wortmannin. Prior exposure to 160 nM and higher of wortmannin for 24 hours reduced the average number of yeast cells ingested by or attached to a single macrophage (P < 0.001) and the ability of the macrophage to kill the baker's yeast (P < 0.05), while wortmannin itself did not affect the yeast. These data provide direct evidence for macrophages being the target cell of wortmannin and further support the notion that impaired macrophage functions are responsible for the immunosuppressive effect of wortmannin previously observed in birds.
Androstadienes↗
The effects of ascorbic acid and iron co-supplementation on the proliferation of 3T3 fibroblasts.
Exposure of 3T3 fibroblasts to FeII reveals a concentration-dependent inhibition of cell proliferation compared to control cells, the apparent threshold for this iron-mediated effect being 5 microM FeII. The inhibition of cell proliferation was accompanied by an enhancement of total malondialdehyde (MDA) levels (as detected directly by hplc) in the cells at higher iron concentrations. The co-supplementation of FeII with varying concentrations of ascorbic acid over the range 5 microM to 240 microM had no significant effect on the threshold for iron toxicity or lipid peroxidation. These results show that there is neither a significant exacerbation of the pro-oxidant effect of FeII nor any protective effect of ascorbate when cultures of 3T3 mouse fibroblasts are exposed to co-supplementation regimes of iron with ascorbic acid.
3T3 Cells↗
Improved procedure for eluting DNA from dried blood spots.
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Alzheimer Disease↗
[Expression of PCNA and protooncogenes during experimental hepatocarcinogenesis in rats].
The expression of PCNA and the protooncogenes of ras family (N-ras, H-ras and Ki-ras) in hepatocarcinoma cells and the proliferating liver cells in precancerous, hyperplastic nodules during experimental hepatocarcinogenesis, induced by diethylnitrosamine in rat liver was observed immunohistochemically and by in situ hybridization. The results indicated that there was a positive expression of PCNA in both the carcinomas cells and precancerous liver cells. The amount of PCNA-positive cells exhibited a negative correlation with the amount of infiltrating mast cells surrounding carcinoma cell nests and the hyperplastic, precancerous nodules. These results basically coincided with that of the separate observation of the expression of protooncogenes in the same study.
Animals↗
Serotonin uptake, storage and metabolism in megakaryoblasts.
Serotonin (5-hydroxytryptamine, 5-HT) uptake, storage and metabolism in human megakaryoblastic cell line (Meg-01) which acts as a model for megakaryocyte precursors, megakaryoblasts were investigated by using biochemical (HPLC) and morphological (electron microscope, EM) techniques. Results showed that Meg-01 cells were able to take up 5-HT. The intracellular 5-HT level was 2.8 +/- 0.4 and 51.8 +/- 4.9 (1 h) or 59.0 +/- 4.4 (2 h) ng/10(6) cells, before and after incubation with 5-HT, respectively, but no dense bodies were visualized after incubation with excess 5-HT by electron microscope observation. This uptake was inhibited by 28% on pre-incubation with fluoxetine and 60% of 5-HT in the cells was released on incubation with reserpine. 5-Hydroxyindoleacetic acid (5-HIAA) concentration of Meg-01 cells was increased after incubation of the cells with 5-HT (0 and 17.6 +/- 2.1 or 19.9 +/- 1.9 ng/10(6) cells, before and after incubation 1 or 2 h, respectively). The study suggests that: (1) 5-HT uptake ability is well established in megakaryocytes precursors, megakaryoblasts and the uptake ability is affected by reserpine and fluoxetine; (2) however, the capacity to store the amine is not well developed in megakaryoblasts and (3) megakaryoblasts may contain monoamine oxidase (MAO) which converts 5-HT to 5-HIAA.
Cells, Cultured↗