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C Yang

Publications and source records attributed to C Yang.

At least 505 records · Page 28Linked to original sources
PubMed1986

[Effect of dexamethasone-A synthetic glucocorticoid hormone on the immune response in pigs].

These experiments were designed to study the effects of a synthetic drug--dexamethasone (DEX) on the immune response of weaned pigs against viral antigen (hog cholera vaccine) and bacterial antigen (formalin inactivated Salmonella enteritis vaccine). Twenty-three five-week-old pigs were divided into eight groups, six of which were injected twice daily with DEX at 1.0 mg or 0.1 mg per Kg of body weight for either four or five days. The other two groups served as controls. During this period, the two 0.1 mg/Kg DEX-treated groups were injected with live hog cholera vaccine at 1.0 or 0.1 dosage respectively. This same treatment was applied to the two 1.0 mg/Kg DEX-treated groups. One control group was injected with a dose of hog cholera vaccine, while the other was given 1.0 ml of Sal. enteritis vaccine. The hog cholera antibody response in DEX-treated pigs was significantly suppressed (p less than 0.01). However, consistent levels of antibody titers were maintained, indicating a slight antibody production. But in pigs injected with one tenth of the normal dose of hog cholera vaccine, there was little or no immune response (p less than 0.01). A comparison of the response of pigs given different levels of DEX concentrations to those with different doses of hog cholera vaccine showed that dexamethasone significantly suppressed antibody production when antigen concentrations were lower. Significant suppression of agglutinating antibody in response to bacterial antigen was also observed at 14 days post-vaccination (p less than 0.05).

Animals↗
PubMed1985

Suppression of defective-sporulation phenotypes by mutations in the major sigma factor gene (rpoD) of Bacillus subtilis.

Mutations (crsA47 and crsA4) in the major sigma factor gene (rpoD) of Bacillus subtilis RNA polymerase have been found to be powerful intergenic suppressors of spoOB, spoOE, spoOF, spoOK and spoIIG mutations. The crsA47 suppressor restores sporulation of spoOE, spoOF, spoOK and spoIIG mutants to levels near those of wild type bacteria and substantially improves the sporulation of a spoOB strain. The crsA mutations are shown to prevent the induction by aliphatic alcohols of SpoO phenocopies in wild type B. subtilis cells.

Bacillus subtilis↗
PubMed1985

Effect of irradiation on immobilized enzymes compared with that on enzymes in solution.

Glucose oxidase and catalase were immobilized by attaching them to nylon fibers that had been treated with triethyloxonium-tetrafluoroborate, diaminohexane and glutardialdehyde according to Morris, Campbell and Hornby (1975). This method assures that the enzymes are bound to a side chain of the polyamide structure. Enzyme activity (as measured by the O2-uptake and by microcalorimetry) was found to be unchanged after 2 years. The apparent Km-constants of the immobilized enzymes with glucose were the same as those for enzymes in solution. GOD and catalase immobilized in poly(acrylamide) gel had the same Km-value. Despite the high stability during storage, the radiation induced inactivation of enzymes immobilized on gel or chromosorb, an inorganic carrier, was of the same order of magnitude as that of the dissolved enzymes. The enzymes bound to nylon fibers showed a higher radiation sensitivity. This might have been caused by an additional attack on the binding site of the carrier.

Catalase↗
PubMed1985

Seroepidemiology of hepatitis B in a population of children in central Tunisia.

The prevalence rate of HBV markers in the overall population was 18.0%. The prevalence rates of HBsAg and anti-HBs were 3.3% and 12.2% respectively. 2.5% of the children were negative for these markers but positive for anti-HBc alone. Of the 17 HBsAg positive children, 10 were HBeAg positive and four were anti-HBe positive. The statistical study using multifactorial correspondence analysis and the chi 2 test showed a positive relationship between the prevalence rate of anti-HBs and age, and a negative relationship between the prevalence rate of 'absence of markers' and age. The male sex and urban dwelling were related to higher prevalence rates of HBsAg and anti-HBc alone and to a lower prevalence rate of 'absence of markers'. No relationship was found between geographical zone, father's education and HBV markers. The implications of these results in terms of prevention are discussed.

Age Factors↗
PubMed1985

Intestinal flora in the second week of life in hospitalized preterm infants fed stored frozen breast milk or a proprietary formula.

Twenty infants fed stored frozen breast milk or a proprietary formula only had both aerobic and anaerobic cultures performed at a chronologic age of 8 to 14 days. Nine out of 10 stools from the infants fed stored frozen breast milk contained Enterobacteriaceae and one stool was sterile. One contained a Pseudomonas species; one contained anaerobic gram-positive rods; one contained anaerobic gram-negative rods; and four contained anaerobic gram-positive cocci. No anaerobes were found in six stools. Six stools had aerobic gram-positive cocci, none of which was hemolytic. Nine out of 10 stools from infants fed a proprietary formula had Enterobacteriaceae. Six stools had anaerobic gram-positive rods, three had anaerobic gram-negative rods, and four had gram-positive cocci. Four stools had no anaerobic bacteria. All 10 stools had nonhemolytic aerobic gram-positive cocci. Enterobacteriaceae were predominant in the stools of the infants fed either stored frozen breast milk or a proprietary formula, and the colony counts of aerobic bacteria were similar in both groups. This pattern of intestinal flora in hospitalized preterm infants in the second week of life is very different from that of normal term infants and may contribute to their increased incidence of systemic and localized infections. The use of stored frozen breast milk for the purpose of suppressing coliform and other potentially pathogenic organisms may not be effective in hospitalized preterm infants who have been treated previously with broad-spectrum, parenteral antibiotics.

Bacteria↗
PubMed1984

[Primary structure of human class II histocompatibility antigens (HLA-D). I. Isolation, purification and characterization of the HLA-D alpha/beta chain complex from a homozygous lymphoblastoid B cell line, H2LCL (HLA-A3,3;B7,7;Dw2, 2;DR2,2;MT1,1;DC1,1;MB1,1].

The complex of alpha and beta chains of HLA-D membrane antigens has been isolated from a lymphoblastoid homozygous B cell line, H2LCL (HLA-A3,3; B7,7; Dw2,2; DR2,2; MT1,1; DC1,1; MB1,1), by an exclusively chemical two-step procedure and characterized by electrophoresis as well as isoelectric focusing in polyacrylamide gel. Cells were gained using long term cultivation in large scale, the crude membrane by differential centrifugation. The proteins of the crude membrane were then solubilized in NP-40, pH 5.0. The first purification step for HLA-D antigens consisted in an ion-exchange chromatography on carboxymethyl cellulose using the solubilization buffer. By this procedure the complex of proteins with relative molecular masses of Mr approximately 34 000 and Mr approximately 29 000 was in a high percentage not bound to the carboxymethyl cellulose. The bound fraction contained the HLA-A, -B and -C antigens and a component with Mr approximately 31 000 corresponding to the well known Ii-fraction. The bound proteins could be recovered from the column by a sodium chloride gradient. The proteins not bound to the carboxymethyl cellulose were precipitated with acetone, dissolved, dialysed against SDS buffer, pH 7.2 and then submitted to the second purification step, the Sephacryl S-300 chromatography. By this procedure the corresponding complex could be further separated from higher and lower molecular proteins. The complex was used as the starting material for the separation of alpha and beta chains. Amino-acid sequences established of the isolated chains have already been communicated.

Amino Acid Sequence↗
PubMed1983

Purification of the group-specific antigen of bluetongue virus by chromatofocusing.

A method for the purification of the precipitating antigen of bluetongue virus (BTV) is described. The results obtained indicate that the precipitating antigen is identical with a core protein of BTV having a molecular weight of 39,000 (P7). So far all bluetongue virus serotypes have been shown to possess this protein. It is evident therefore that a group-specific reaction could be based on the presence of antibodies against this core protein. The purification of this protein by chromatofocusing proved relatively easy to perform and immunodiffusion tests revealed a group-specific reaction.

Antigens, Viral↗
PubMed1983

Primary structure of human class II histocompatibility antigens 3rd communication. Amino acid sequence comparison between DR and DC subclass antigens derived from a lymphoblastoid B cell line homozygous at the HLA loci (HLA-A3,3; B7,7; Dw2,2; DR2,2: MT1,1; Dc1,1: MB1,1).

Class II histocompatibility antigens from a homozygous human lymphoblastoid B cell line (HLA-A3,3; B7,7; Dw2,2; DR2,2; MT1,1; DC1,1; MB1,1) were isolated by an exclusively chemical procedure. After the separation of the alpha and beta chains the amino acid sequences of the extracellular parts of the DR2 alpha and the DR2 beta chains could be determined, in spite of the heterogeneity of both fractions. Peptides isolated in considerably lower yields indicated at least one more alpha chain and 6 further beta chains. By the investigation of these lower-yield enzymatic fragments, in addition to the DR2 alpha and DR2 beta chains, we can now report on the partial amino acid sequences of a DC alpha chain, a second beta chain of DR type and one beta chain of DC type. Furthermore, the isolation of a characteristic glycopeptide suggests the existence of a second beta chain of DC type. The following class II antigens are therefore identified: DR2 alpha/DR2 beta 1, DR2 alpha/DR2 beta 2, DC1 alpha/DC1 beta 1, DC1 alpha/DC1 beta 2, indicating that each subclass can be subdivided into two antigens because each alpha chain type can associate with at least either beta 1 or beta 2. Further investigations must clarify whether the remaining three beta chains are of the DR, DC, or of a third beta chain type. Amino acid sequence comparisons confirm that the human DR antigens are the equivalent of mouse I-E antigens, while human DC antigens are the equivalent of mouse I-A antigens.

Amino Acid Sequence↗
PubMed1982

The operation of autoregulatory feedback loops in noradrenergic transmission to cardiovascular effector tissues.

The effects of alpha-adrenoceptor blocking drugs on circulating catecholamines or neurogenically released noradrenaline will depend on their relative selectivity for prejunctional or postjunctional alpha-adrenoceptors. Relatively selective prejunctional alpha-adrenoceptor antagonists will block the inhibitory feedback mechanism at sympathetic nerve terminals, thus increasing transmitter release, which will tend to overcome any postjunctional alpha-adrenoceptor blockade, and responses to sympathetic nerve stimulation will be resistant to blockade. They will have noradrenolytic activity in doses which are not sympatholytic; they may even enhance sympathetic nerve activity. In contrast, selective postjunctional alpha-adrenoceptor blocking drugs will be noradrenolytic and sympatholytic. Prazosin has weak prejunctional alpha-adrenoceptors blocking activity, but is relatively selective for postjunctional alpha-adrenoceptors. Yohimbine is relatively selective for prejunctional alpha-adrenoceptors, and phentolamine is not highly selective. Selectivity for postjunctional alpha-adrenoceptors appears to be a desirable action for an antihypertensive drug of this type.

Adrenergic alpha-Antagonists↗
PubMed1982

[Primary structure of class II human histocompatibility antigens. 2nd Communication. Amino acid sequence of the N-terminal 179 residues of the alpha-chain of an HLA-Dw2/DR2 alloantigen (author's transl)].

From a lymphoblastoid homozygous cell-line (HLA-A3,3; B7,7; Dw2,2; DR2,2) the alpha-chain of the HLA-Dw2/DR2 antigen was isolated by an exclusively chemical procedure. The alpha- was separated from the beta-chain by chromatography with hydroxylapatite in Na-dodecyl sulfate. Here we describe the amino acid sequence of the alpha-chain up to Position 179. The molecule is divided into two domains which do not appear homologous to each other but show a significant homology to the beta-chain (21.2%). The similarity is larger in the second (27%) than in the first (15.5%) domain, indicating a different evolutionary relationship for both parts. In contrast to the beta-chain both domains contain an N-glycosidically linked carbohydrate. The methionines are positioned only in the N-terminal, the cysteines exclusively in the C-terminal domain. Only the latter can therefore be stabilized by a disulfide bridge. As with the beta-chain the regions around the cysteines show a remarkable similarity with the constant C-terminal domains of k-, lambda-, alpha-, gamma-, sigma-, epsilon- and mu-chains of immunoglobulins. Although to a considerably lesser extent, the alpha-chain preparation also shows a heterogeneity at the protein level. Since the employed cell-line is homozygous with regard to HLA-D/DR, our results indicate that at least two alpha-chain genes exist in the HLA-D/DR-region. Together with the already published sequence of the beta-chain, the extracellular part of an histocompatibility antigen of the HLA-D type is now known.

Amino Acid Sequence↗
PubMed1982

Methyldopa: single daily dose versus multiple daily dose.

A single-blind, prospective, crossover study of 27 ambulatory hypertensive outpatients was conducted to compare the antihypertensive effects of single daily dose versus multiple daily dose methyldopa regimens. Patients were randomly assigned to the two treatment modalities for a four-week study period. After four weeks patients were crossed over to the other study regimen. Each patient's blood pressure was determined three times daily, once each week. At the end of the study both treatment modalities were equally effective in controlling blood pressure levels. No serious adverse reactions were detected. This study has shown that patients currently on divided daily doses of methyldopa can be effectively treated on a single total dose of the medication.

Adult↗