Search PubMed⌕ Search

Biomedical subjects

M Yang

Publications and source records attributed to M Yang.

At least 271 records · Page 15Linked to original sources
PubMed1998

Neglect and constructive disorder.

A 61 year-old right handed man, who suffered from right cerebral infarction with evidences of visual-spatial neglect and constructive disorder, was reported. When copying simple geometric designs, he omitted to copy figures on the left side of the page; he tended to bisect the line to the right of the line's real center; after memorizing the familiar pictures he mainly mentioned the pictures on the right side of the page; when copying the "Rey Complex" he also ignored the structures on the left side. The relations of the neglect and construction disorder are discussed.

Apraxias↗
PubMed1998

Comparison of human alpha1-adrenoceptor subtype coupling to protein kinase C activation and related signalling pathways.

The coupling of human alpha1-adrenoceptor subtypes to protein kinase C (PKC) and PKC-related signalling events were investigated in rat-1 fibroblasts stably expressing alpha1A-, alpha1B- or alpha1D-adrenoceptors at densities of 1328+/-200, 5030+/-703 and 150+/-14 fmol/mg protein respectively. In functional assays the alpha1-adrenoceptor agonist phenylephrine significantly stimulated PKC (assessed as increased activity in the membrane fraction) in cells expressing alpha1A- or alpha1B- but not alpha1D-adrenoceptors. In immunoblot assays phorbol ester treatment enhanced membrane-associated immunoreactivity of PKCalpha, PKCdelta and PKCepsilon to a similar extent in all three cell lines. Stimulation of alpha1A- and alpha1B-adrenoceptors also increased immunoreactivity of PKCalpha, PKCdelta and PKCepsilon in the membrane fraction, while alpha1D-adrenoceptor stimulation yielded only very small and inconsistent alterations. Immunoreactivity of PKCzeta was not consistently affected by phorbol ester or phenylephrine in any of the cell lines. Stimulation of all three alpha1-adrenoceptors time- and concentration-dependently increased inositol phosphate formation. Maximum activation occurred with the order alpha1A approximately = alpha1B > alpha1D. Phenylephrine also concentration dependently elevated free intracellular [Ca2+] in all three cell lines with the order of efficacy alpha1A > alpha1B > alpha1D. In the presence of ethanol, phenylephrine stimulated phosphatidylethanol formation in alpha1A- and alpha1B-adrenoceptor-expressing cells time and concentration dependently but only weakly and inconsistently in alpha1D-adrenoceptor-expressing cells. The efficacy of phenylephrine (100 microM) relative to that of noradrenaline (100 microM) for stimulation of phosphatidylethanol formation was similar (> or = 75%) for all three subtypes. The alkylating agent phenoxybenzamine concentration dependently reduced alpha1A-adrenoceptor density and phenylephrine-stimulated Ca2+ elevations to levels seen with alpha1D-adrenoceptors but reductions of phenylephrine-stimulated phosphatidylethanol formation were weaker. We conclude that human alpha1A- and alpha1B-adrenoceptors expressed in rat-1 cells couple to activation of PKCalpha, PKCdelta and PKCepsilon but not PKCzeta; this may involve stimulation of phospholipases C and D and intracellular Ca2+ elevations. Activation of these pathways by alpha1D-adrenoceptors appears to be much weaker and was not detected consistently; this was not fully explained by weak partial agonism of phenylephrine at this subtype or by lower receptor densities. Overall the alpha1A-adrenoceptor may have the highest efficiency of stimulus-response coupling among human alpha1-adrenoceptor subtypes.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1998

Contribution of carbon monoxide-producing cells in the gastric mucosa of rat and monkey.

Recent studies have shown that carbon monoxide (CO) may function as a gaseous signaling molecule in a similar way to nitric oxide. In the gastrointestinal tract, immunoreactivity against a CO-producing enzyme, heme oxygenase-2 (HO-2), was reported in epithelial cells and neurons of submucosal and myenteric plexus. However, details of the epithelial cells in the gastric mucosa remain unknown. The aim of this study was to clarify if mRNA for HO-2 is expressed in the rat stomach, if HO-2 protein is present in the mucosa, and to define the cell types of the HO-2-immunoreactive cells. HO-2 mRNA and protein were detected in fundic and pyloric mucosa of rat stomach using an RNA protection assay and western blot analysis. Immunohistochemical study showed that HO-2 was localized in parietal cells of the fundic glands and gastrin cells of the pyloric glands of both rat and monkey. The results suggest that HO-2 enzyme is produced in the gastric mucosa, and that CO is released from parietal cells and gastrin cells.

Amino Acid Sequence↗
PubMed1998

Divergent regulation of stomatal initiation and patterning in organ and suborgan regions of the Arabidopsis mutants too many mouths and four lips.

Stomata are consistently patterned so that they are not in contact. This patterning is violated in the too many mouths (tmm) and four lips (flp) mutations of Arabidopsis thaliana (L.) Heynh. which have stomatal clusters in the first-formed leaves. To clarify the function of both genes in stomatal initiation and patterning, the phenotypes of many different organs were quantified. The flp mutation affects dorsiventral and cylindrical organs differentially with respect to the frequency of clustering. The tmm mutation has a more complex region-specific phenotype in that some regions lack stomata entirely, other regions have excess stomata, and the flower stalk exhibits an apex-to-base gradient from excess to no stomata. This suggests that TMM represents an unusual type of gene regulating plant cell development in that it can either influence stomatal initiation in a positive or negative fashion depending on region. Since the frequencies of initiation and clustering can be uncoupled in tmm, these two functions are under separate region-specific control. Analysis of double mutants shows that tmm and flp in some cases show region-specific interactions in both cluster formation and initiation, and that there may be subpopulations of stomata under different genetic control.

Arabidopsis↗
PubMed1998

Synthesis of aryl 3'-sulfo-beta-lactosides as fluorogenic and chromogenic substrates for ceramide glycanases.

We have previously reported that 4-methylumbelliferyl 6'-O-benzyl-beta-lactoside (2) is a useful substrate for a fluorometric assay of ceramide glycanase (CGase) (L.-X. Wang, N. V. Pavlova, S.-C. Li, Y.-T. Li and Y. C. Lee, Glycoconjugate J., 13 (1996) 359-365). The introduction of a 6-O-benzyl group at the terminal Gal efficiently protected the substrate from its hydrolysis by exo-galactosidase, permitting the assay of CGase in crude biological materials. However, a drawback of this substrate is its low water-solubility and relatively high Km (at a mM level). Introduction of a sulfate group into 4-methylumbelliferyl beta-lactoside (1) led to the formation of 4-methylumbelliferyl 3'-O-sulfo-beta-lactoside (3), which was found to be a more effective substrate than 2. Moreover, the presence of a 3'-O-sulfate group not only increases the water solubility tremendously, but also protects the substrate from cleavage by exo-beta-galactosidase as the 6'-O-benzyl group in 2 does. In addition to the fluorogenic substrate (3), two sulfated chromogenic substrates, N-tetradecanoyl-4-O(3'-sulfo-beta-lactosyl)-3-nitro-L-tyrosine methyl ester (9) and 2-N-(tetradecanoylamino)-4-nitro-phenyl 3'-sulfo-beta-lactoside (12), were synthesized and their suitability for a photometric assay of CGase was evaluated. Substrates 9 and 12, with a long fatty acid chain attached to the aglycon part, have a Km value close to that of the natural substrate GM1 (at a microM level).

Chromogenic Compounds↗
PubMed1998

Evaluation of seven PCR-based assays for the analysis of microchimerism.

OBJECTIVE: The presence of small numbers of cells of donor origin in the circulation of recipients of organ transplants (microchimerism) may correlate with immunologic tolerance. As part of our ongoing studies on microchimerism, we evaluated the utility of seven PCR-based assays for the detection of the less abundant DNA in paired mixtures (100 ng total DNA). DESIGN AND METHODS: DNA samples were screened to identify pairs informative for one or more PCR assays. DNA mixtures from the informative pairs were then analyzed using at least one assay. The assays were based on the X-Y homologous region; a Y chromosome microsatellite locus; three autosomal microsatellite loci; the D1S80 minisatellite locus; and sequence specific oligonucleotide probe (SSOP) analysis of the HLA DRB1 locus. RESULTS: About 0.1% of male DNA against a background of female DNA was detectable using primers for the X-Y homologous region, but the sensitivity was increased to 0.0001% using nested primers for the Y chromosome microsatellite marker. Analysis of the minor DNA component was difficult with the three autosomal microsatellite assays because of the presence of shadow bands. Similar problems with the D1S80 assay were resolved using more stringent PCR conditions, and the sensitivity was 0.1%. Using the DRB1 locus, we were able to detect 1% DNA in the mixed samples. CONCLUSIONS: These studies show that: (a) nested PCR for the Y chromosome is the most sensitive assay for the detection of microchimerism; (b) D1S80 is a useful marker for microchimerism; (c) additional optimization of analytical conditions is required if autosomal microsatellite markers and the SSOP assay are to be used for microchimerism analysis.

Female↗
PubMed1998

CD8+ T cells inhibit immunoglobulin E synthesis in low responder SJL/J mice.

In an effort to examine the basis for low IgE responsiveness of SJL/J strain mice, we analysed the profiles of cytokines, such as interleukin-2 (IL-2), IL-4 and interferon-gamma (IFN-gamma), in SJL/J and A.SW/SnJ mice following immunization. Splenocytes of ovalbumin (OVA)-immunized SJL/J mice, secreted significantly higher levels of IL-4 and lower levels of IFN-gamma than those of A.SW/SnJ mice. A time-course analysis of cytokine expression in in vitro cultures of spleen cells indicated that the levels of IL-4 and IL-2 remained persistently high throughout in the cultures of SJL/J splenocytes as opposed to those of A.SW/SnJ. Depletion of CD4+ T cells in vivo suppressed the production of IL-2, IL-4 and IFN-gamma suggesting that CD4 T cells are the producers of most cytokines in both SJL/J and A.SW/SnJ mice. Depletion of CD8+ T cells in vivo not only induced productive epsilon transcript but also enhanced IgE production in SJL/J mice. Moreover, CD8 depletion in SJL/J mice led to decreased production of IFN-gamma, resulting in a net decrease in the ratio of IFN-gamma to IL-4. A similar shift in the IFN-gamma/IL-4 ratio was found in splenocytes of SJL/J mice following irradiation, which is known to enhance IgE synthesis in these mice. Taken together, it is concluded that low IgE responsiveness in SJL/J mice is not due to a defect in IL-4 production per se. Increased IFN-gamma production by the CD8+ T cells inhibits class switch and suppresses IgE antibody production in SJL/J mice.

Animals↗
PubMed1998

Prolactin-induced expression of TATA-less cyclin D3 gene is mediated by Sp1 and AP2.

The TATA-less cyclin D3 gene is stimulated by prolactin (PRL) in rat Nb2 T-lymphocytes. DNA mobility shift assay and luciferase transfection analysis revealed that the gene has a potential promoter region, two enhancer domanins and a silencer region. The promoter region possessed three Sp1 sites and two AP2 sites, and both enhancer regions had one AP2 binding site each. Analysis using oligonucleotide probes and purified AP2 protein has suggested that the expression of rat cyclin D3 gene is promoted by Sp1 and AP2 factors.

Animals↗
PubMed1998

Predictors of overweight and overfatness in a multiethnic pediatric population. Child and Adolescent Trial for Cardiovascular Health Collaborative Research Group.

The goal of the study was to determine whether overweight or overfatness were predicted from sex, race or ethnicity, school site, and intervention or control status for children who were 9 y old at the outset of the Child and Adolescent Trial for Cardiovascular Health (CATCH). In this ethnically and geographically diverse group of 5106 students, height, weight, and triceps skinfold thickness were measured at 9 (baseline) and 11 y (follow-up) of age. The strongest predictors of status at follow-up were baseline overweight (odds ratio: 69.0; 95% CI: 54.9, 96.3) and overfatness (odds ratio: 27.4; 95% CI: 22.4, 33.4); site, African American race or ethnicity, and male sex were also significant independent associations. Children in the overweight (> 85th percentile for body mass index) group had significantly higher adjusted means for total blood cholesterol, higher apolipoprotein B concentrations, lower mean HDL-cholesterol concentrations, and lower performance on the 9-min run than those in other groups (< 15th, 15-49th, or 50-85th body mass index percentiles). Similar results were found for these factors for those subjects with greater triceps skinfold-thickness measurements. Groups of children who were overweight and overfat at baseline were more likely to be overweight and overfat at follow-up and to have more cardiovascular risk factors than their peers.

Apolipoproteins B↗
PubMed1998

Light promotion of hypocotyl gravitropism of a starch-deficient tobacco mutant correlates with plastid enlargement and sedimentation.

Dark-grown hypocotyls of a starch-deficient mutant (NS458) of tobacco (Nicotiana sylvestris) lack amyloplasts and plastid sedimentation, and have severely reduced gravitropism. However, gravitropism improved dramatically when NS458 seedlings were grown in the light. To determine the extent of this improvement and whether mutant hypocotyls contain sedimented amyloplasts, gravitropic sensitivity (induction time and intermittent stimulation) and plastid size and position in the endodermis were measured in seedlings grown for 8 d in the light. Light-grown NS458 hypocotyls were gravitropic but were less sensitive than the wild type (WT). Starch occupied 10% of the volume of NS458 plastids grown in both the light and the dark, whereas WT plastids were essentially filled with starch in both treatments. Light increased plastid size twice as much in the mutant as in the WT. Plastids in light-grown NS458 were sedimented, presumably because of their larger size and greater total starch content. The induction by light of plastid sedimentation in NS458 provides new evidence for the role of plastid mass and sedimentation in stem gravitropic sensing. Because the mutant is not as sensitive as the WT, NS458 plastids may not have sufficient mass to provide full gravitropic sensitivity.

Darkness↗
PubMed1998

Experimental infection of Mongolian gerbils with wild-type and mutant Helicobacter pylori strains.

Experimental Helicobacter pylori infection was studied in Mongolian gerbils with fresh human isolates that carry or do not carry cagA (cagA-positive or cagA-negative, respectively), multiply passaged laboratory strains, wild-type strain G1.1, or isogenic ureA, cagA, or vacA mutants of G1.1. Animals were sacrificed 1 to 32 weeks after challenge, the stomach was removed from each animal for quantitative culture, urease test, and histologic testing, and blood was collected for antibody determinations. No colonization occurred after >/=20 in vitro passages of wild-type strain G1.1 or with the ureA mutant of G1.1. In contrast, infection occurred in animals challenged with wild-type G1.1 (99 of 101 animals) or the cagA (25 of 25) or vacA (25 of 29) mutant of G1.1. Infection with G1.1 persisted for at least 8 months. All 15 animals challenged with any of three fresh human cagA-positive isolates became infected, in contrast to only 6 (23%) of 26 animals challenged with one of four fresh human cagA-negative isolates (P < 0.001). Similar to infection in humans, H. pylori colonization of gerbils induced gastric inflammation and a systemic antibody response to H. pylori antigens. These data confirm the utility of gerbils as an animal model of H. pylori infection and indicate the importance of bacterial strain characteristics for successful infection.

Animals↗
PubMed1998

Expression and distribution of heme oxygenase-2 mRNA and protein in rat kidney.

Recent studies suggest that carbon monoxide (CO), which is formed by the enzyme heme oxygenase (HO) during the conversion of heme to biliverdin, shares some of the chemical and biological properties of nitric oxide (NO) and may play roles similar to those of NO. Heme oxygenase activity in the kidney has been reported for many years, and there are some reports on the expression of mRNA for two HO isozymes (HO-1 and HO-2) and cellular localization of HO-1 protein. However, cellular localization of HO-2 protein in the kidney under normal conditions has not been reported. In the present study we examined the expression and distribution of HO-2 mRNA and HO-2 protein in rat kidney using RNA protection assay and light and electron immunocytochemistry. RNA protection assay confirmed constitutive expression of HO-2 transcript in rat kidney. HO-2 immunoreactivity was selectively found in epithelial cells of the thick ascending limb and distal convoluted tubule, connecting tubule cells, and principal cells of the collecting duct. These results suggest that HO-2 is synthesized in the kidney and that HO-2 in the epithelial cells of renal tubules may serve as a source for CO generation under normal conditions.

Animals↗
PubMed1998

[Changes in serum levels of total amino acids in young children with congenital heart diseases].

OBJECTIVE: To study the implication of early surgical operation on the improvement of protein malnutrition in young children with congenital heart diseases. METHODS: Sixteen kinds of serum free amino acids were determined with an automatic analyzer for 72 cases with congenital heart diseases before and after surgical operation and 51 healthy children. RESULTS: Serum total amount of essential amino acids reduced in children with congenital heart diseases, mainly of branch-chained amino acids, especially significant in young ones. Serum amino acids restored to normal level one month after surgical operation. CONCLUSION: There existed protein malnutrition in children with congenital heart diseases, especially in young ones. Surgical operation for them in a suitable time will improve their protein nutritional status.

Adolescent↗
PubMed1998

[Reconstruction of the floor of mouth with facial artery musculocutaneous flap].

In order to study the clinical efficacy of facial artery musculocutaneous flap on repairing the defect of the floor of mouth, 21 patients had received this type of treatment from 1991 to 1997. The size of the flaps ranged from 8.0 x 3.4 cm to 12.1 x 5.4 cm and the average age of these patients was 59.5 years old. The donor site was closed directly. Nineteen flaps survived completely, while necrosis occurred at the apex of the other 2 flaps, which healed by ordinary management. The applied anatomy of the flap and the design and the main points of the operation were reported in details. The advantage of the flap and the prevention of facial malformation following operation were discussed. The conclusion was that this type of flap was ideal for reconstruction of the defects of floor of the mouth.

Adult↗
PubMed1998

[One stage repair of intraoral defects after radical operation of oral carcinoma by facial vessels pedicled naso-labial myocutaneous flap].

In order to repair the intraoral defects after extensive resection of oral carcinoma with radical neck lymph nodes dissection, the nasolabial myocutaneous flap was prepared with its pedicle which only contained the facial artery and anterior facial vein. After removal of the tumor, the flap was used to cover the intraoral defect. Altogether 15 cases of oral squamous cell carcinoma were treated by this method. Seven out of 15 cases had their cervical lymph nodes involved. The tumor in all cases were located in one anatomical region, without involvement of accessory nerve or metastasis. All the flaps survived after the operation. There was no recurrence of tumor in any case after being followed up from 0.5-2 years. Removal of tumor and repaire of the defect by pedided naso-labial myocutaneous flap could be done in one stage. The detail of the process was introduced. Its feasibility and application were discussed. It was suggested that preserving the facial vessels be a kind of modified method of radical neck lymph nodes dissection, and the nasolabial myocutaneous flap have some clinical value in repair of the defect after radical operation of oral carcinoma.

Adult↗
PubMed1998

[The flag venous flap in the dorsal finger].

OBJECTIVE: To improve the design and application of the flag flap. METHOD: Based on the anatomical characteristics of the dorsal digital veins and the venous arch, the flag flap pedicled with the veins in the dorsum of the finger was used to repair the skin defects of the ventral finger and hand in six cases. RESULTS: All flaps survived with primary healing. Three months' follow-up showed that the function and appearance of the finger were satisfactory. CONCLUSION: The design of the flap broadens its application in repairing the defects on the ventral finger and hand.

Adolescent↗
PubMed1998

[The changes of maternal and umbilical serum nitric oxide in patients with pregnancy induced hypertension].

OBJECTIVE: To determine whether levels of maternal and umbilical serum nitric oxide (NO) were changed in patients with pregnancy induced hypertension (PIH). METHODS: 40 women with PIH, 40 normal late trimester pregnant women and 20 nonpregnant women were studied. Maternal venous blood were collected from all the cases and umbilical venous blood were collected from 28 of the first two groups respectively. Serum NO2-/NO3-, the endproducts of NO, were measured with the Griess reaction after reduction with nitrate reductase. RESULTS: The mean NO2-/NO3- in maternal venous serum were 23.30 +/- 5.60 mumol/L in nonpregnant group, 26.42 +/- 4.54 mumol/L in normal pregnant group and 32.58 +/- 5.06 mumol/L in PIH group. Umbilical serum NO2-/NO3- were 12.26 +/- 4.91 mumol/L in normotensive groups and 14.64 +/- 3.90 mumol/L in PIH group. Maternal serum NO2-/NO3- in nonpregnant group were lower than that both in normal pregnant group (P < 0.05) and in PIH group (P < 0.01). Compared with the normotensive group, maternal serum NO2-/NO3- in PIH group was significantly higher (P < 0.01), while significantly higher serum NO2-/NO3- were also found in umbilical venous blood in PIH group (P < 0.05). There were no correlations between serum NO2-/NO3- level and blood pressure or birth weight. The total nitrite levels in fetal circulation was lower than that in maternal circulation in both pregnant groups (P < 0.01). CONCLUSION: Total nitrites are increased both in maternal and fetal circulation in PIH. The result indicates that the increase of NO may be secondary compensative reaction in PIH.

Female↗