Search PubMed⌕ Search

Biomedical subjects

S Zheng

Publications and source records attributed to S Zheng.

At least 55 records · Page 3Linked to original sources
PubMed2001

Regulation of plant water loss by manipulating the expression of phospholipase Dalpha.

Phospholipase D (PLD) has been implicated in various processes, including signal transduction, membrane trafficking, and membrane degradation. Multiple forms of PLD with distinct biochemical properties have been described in the cell. In Arabidopsis, PLDalpha and PLDgamma, but not PLDbeta, were detected in guard cells, and antisense suppression resulted in a specific loss of PLDalpha. The abrogation of PLDalpha rendered plants less sensitive to abscisic acid and impaired stomatal closure induced by water deficits. PLDalpha-depleted plants exhibited accelerated transpirational water loss and a decreased ability to tolerate drought stress. Overexpression of PLDalpha enhanced the leaf's sensitivity to abscisic acid. These findings provide molecular and physiological evidence that PLDalpha plays a crucial role in regulating stomatal movement and plant-water status.

Abscisic Acid↗
PubMed2001

Differential expression of adenylyl cyclases in the rat nephron.

BACKGROUND: Adenylyl cyclases (ACs) are a family of enzymes that catalyze the formation of the second-messenger cyclic adenosine 3',5'-monophosphate (cAMP). At least nine isoforms of AC have been cloned. These isoforms differ in their tissue distribution and basal activity. AC isoforms also differ in their capacity to be stimulated or inhibited by G protein alpha(i), alpha(s) and beta/gamma subunits, protein kinase C, and intracellular calcium. The distribution of ACs in the kidney is only partially known, although it is known that ACs play important roles in kidney signal transduction. Several receptors are known to couple to AC, but their linkage to individual AC isoforms in the kidney is not known. METHODS: This study investigated the tissue distribution of AC isoforms along the nephron of Wistar-Kyoto rats using reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry, and immunoblotting. RESULTS: While AC VI and IX mRNA were found in all nephron segments, there was no expression of AC VIII mRNA. ACs II through V and VII mRNA were variably found in specific nephron segments. mRNA for AC isoforms II, III, VI, VII, and IX were expressed in renal proximal tubules. All of the AC isoforms studied, except VIII, were found in glomeruli. Immunoblotting and immunohistochemistry confirmed the mRNA results. AC isoforms II, III, IV, and IX were expressed in luminal rather than in basolateral membranes. However, immunohistochemical studies were not feasible for the other isoforms that could be expressed in basolateral membranes. CONCLUSION: Knowledge of the distribution of ACs may help establish the linkage between receptors and specific AC isoforms and define their functions.

Adenylyl Cyclases↗
PubMed2001

Compensatory phospholipid digestion is required for cholesterol absorption in pancreatic phospholipase A(2)-deficient mice.

BACKGROUND AND AIMS: Numerous studies have suggested phospholipid inhibition of dietary cholesterol absorption through the gastrointestinal tract. This study addressed the importance of luminal phospholipid hydrolysis in this process. METHODS: The effect of phospholipase inhibition on cholesterol transport from intestinal lumen to the lymphatics was evaluated in lymph fistula rats. Cholesterol and phospholipid absorption efficiency in intact animals was evaluated in control and phospholipase A(2) (PLA2) gene-targeted mice. RESULTS: The PLA2 inhibitor FPL 67047XX retarded cholesterol absorption in a lymph fistula rat model. Under basal chow-fed dietary conditions, cholesterol absorption efficiency from a single bolus meal, and plasma lipid levels, were similar among PLA2+/+, PLA2+/-, and PLA2-/- mice. Interestingly, the nonhydrolyzable phospholipid dioleoyl ether phosphatidylcholine suppressed cholesterol absorption by 10% to 18% in mice without regard to their PLA2 genotype. When 1-palmitoyl-2-[(14)C]oleoyl-phosphatidylcholine was used as the substrate, the radiolabeled phospholipid was found to be hydrolyzed and absorbed with equal efficiency in PLA2+/+, PLA2+/-, and PLA2-/- mice. CONCLUSIONS: These results suggested that although phospholipid digestion in the intestinal lumen is a prerequisite for efficient cholesterol absorption, additional enzyme(s) can compensate for pancreatic PLA2 in catalyzing phospholipid digestion and facilitating cholesterol absorption in PLA2 knockout mice.

Animals↗
PubMed2001

Surfactant and inhaled nitric oxide in rats alleviate acute lung injury induced by intestinal ischemia and reperfusion.

BACKGROUND: Respiratory distress and acute lung injury (ALI) are severe complications of intestinal ischemia and reperfusion injury (I/R). The authors hypothesize that a combined surfactant and inhaled nitric oxide (iNO) may alleviate I/R-induced ALI. METHODS: Adult rats (body weight 285 to 315 g, n = 45) were allocated randomly to either a negative control group (N-Control, n = 9) with only sham laparotomy, or groups (n = 9 each) for induction of I/R by occlusion of superior mesenteric artery, followed by treatment with (1) surfactant at 100 mg/kg (Surf), (2) iNO at 20 ppm (NO), (3) both surfactant and iNO (SNO), or (4) no surfactant no iNO (a positive control, P-Control). Mechanical ventilation was provided for 120 minutes with variable peak insufflation pressure and FIO2 to achieve adequate arterial pH, PaO2, and PaCO2. Blood gas values, dynamic lung compliance (Cdyn), and airway resistance (Raw) were measured during the 2-hour treatment. Lung wet-to-dry weight ratio (W/D), histopathology, and morphometric analysis of alveolar expansion (V(V)) were determined at the end of the experiment. RESULTS: After 120 minutes of treatment, the SNO group had the highest PaO2 and Cdyn values, close to that of the N-Control group. The Surf, NO, and SNO groups had higher V(V) and lower CV (V(V)) values than the P-Control, but modest decrease of W/D values. The NO group had moderately improved PaO2 but Cdyn and V(V) were as low as that of the P-Control. The lungs of the SNO group had significantly alleviated edema and neutrophil infiltration compared with the P-Control. CONCLUSIONS: The combined surfactant and iNO treatment alleviated rat ALI induced by I/R, and exerted effects better than the use of surfactant or iNO alone.

Administration, Inhalation↗
PubMed2001

Study on sludge expansion during treatment of salad oil manufacturing wastewater by yeast.

Five yeast strains, namely Rhodotorula rubra, Candida tropicalis, Candida utilis, Candida boidinii, Trichosporon cutaneum, were isolated from soil spots of a salad oil factory, and applied for continuous treatment of salad oil manufacturing wastewater. The oil and COD removal performance of the mixed cultures were comparable to the results other researchers obtained. Sludge expansion, accompanied with sludge morphology change from pseudomycelia to true mycelia, occurred during continuous treatment of wastewater. The true mycelia dominated sludge had a much higher water content and SVI value than that of the yeast pure cultures, although the two kinds of sludge had similar oil removal performance. A mold, Geotrichum candidum, was isolated from the expanded sludge, and was suspected to be a reason for sludge expansion. Addition of 0.3% sodium propionate into batch cultures degraded SVI value from around 100 to 60. In a continuous running, addition of 10 mg l-1 sodium hypochlorite decreased SVI value from over 200 to below 100. The yeast activity, however, was weakened to a large extent at the same time.

Industry↗
PubMed2001

Th1/Th2 predominance and proinflammatory cytokines determine the clinicopathological severity of IgA nephropathy.

BACKGROUND: IgA nephropathy is one of the most common forms of primary glomerulonephritis in adults. Its pathogenesis is complex. The nature of infiltrating and proliferating cells and of cellular mediators could contribute to the progression of IgA nephropathy towards end-stage renal failure. METHODS: To evaluate this hypothesis, we attempted to quantify the magnitude of intrarenal gene expression of various cytokines (IL-1 beta, TNF-alpha, IL-6, IL-15, IL-2, IFN-gamma, IL-10) and chemokines (IL-8, RANTES, MCP-1) in 48 renal core biopsy specimens, diagnosed as IgA nephropathy by immunofluorescence microscopy. Semi-quantitative reverse-transcriptase polymerase chain reaction using internal competitors was used for the quantification of gene transcripts. RESULTS: The expression of intrarenal gene transcripts of various cytokines and chemokines was closely interrelated, but not associated with the pathological grading system. The IFN-gamma/IL-10 ratio was higher in patients with renal dysfunction than in those with normal renal function (P=0.0483). Gene transcript levels of proinflammatory cytokines were related to the amount of proteinuria. In patients with severe glomerular sclerosis, the ratio of IFN-gamma/IL-10 gene transcripts was high (P=0.04). IL-10 gene transcript level was related to the severity of tubulointerstitial damage. The levels of gene expression of IL-10 (P=0.009), IFN-gamma (P=0.03), and TNF-alpha (P=0.005) were related to the degree of mesangial matrix expansion and the extent of intrarenal arteriolar changes correlated with the expression of the IL-8 gene transcript (r=0.43, P=0.004). CONCLUSIONS: We propose that Th1/Th2 predominance and the level of proinflammatory cytokines could determine the pathogenetic processes and the severity of the clinical manifestations of IgA nephropathy.

Adolescent↗
PubMed2001

Intestinal satiety protein apolipoprotein AIV is synthesized and regulated in rat hypothalamus.

Apolipoprotein AIV (apo AIV) is a satiety protein secreted by the small intestine. We demonstrate for the first time that apo AIV protein and apo AIV mRNA are present in rat hypothalamus, a site intimately involved in the integration of signals for regulation of food intake and energy metabolism. We further characterized the regulation of hypothalamic apo AIV mRNA levels. Food-deprived animals showed a pronounced decrease in gene expression of apo AIV in the hypothalamus, with a concomitant decrease in the jejunum. Refeeding fasted rats with standard laboratory chow for 4 h evokes a significant increase of apo AIV mRNA in jejunum but not in hypothalamus. However, lipid refeeding to the fasted animals restored apo AIV mRNA levels both in hypothalamus and jejunum. Intracerebroventricular administration of apo AIV antiserum not only stimulated feeding, but also decreased apo AIV mRNA level in the hypothalamus. These data further confirm the central role of apo AIV in the regulation of food intake.

Animals↗
PubMed2001

D(1) dopamine receptor regulation of NHE3 during development in spontaneously hypertensive rats.

To determine if the defective interactions among D(1)-like receptors, G proteins, and Na(+)/H(+) exchanger 3 (NHE3) are consequences of hypertension, we studied these interactions in rats, before (2--3 wk) and after (12 wk) the establishment of hypertension. To eliminate the confounding influence of second messenger action on D(1) receptor-NHE3 interaction, studies were performed in renal brush-border membranes (BBM) devoid of cytoplasmic second messengers. NHE3 activity increased with age in Wistar-Kyoto (WKY) rats (3 wk = 1.48 +/- 0.39, n = 13; 12 wk = 2.83 +/- 0.15, n = 16, P < 0.05) but not in spontaneously hypertensive rats (SHRs; 3 wk = 2.52 +/- 0.37, n = 11; 12 wk = 2.81 +/- 0.20, n = 16). D(1) receptor protein tended to decrease, whereas NHE3 protein tended to increase with age in both WKY and SHRs. However, the inhibitory effect of a D(1)-like agonist, SKF-81297, on NHE3 activity increased with age in WKY rats (3 wk = -40.7 +/- 5.3%, n = 10, 12 wk = -58.7 +/- 4.6%, n = 12, P < 0.05) but not in SHRs (3 wk = -27.6 +/- 5.9%, n = 11, 12 wk = -25.1 +/- 3.2%, n = 11). The decreased inhibitory effect of another D(1)-like agonist, fenoldopam, on NHE3 activity in SHRs was not caused by increased activity and binding of G beta gamma to NHE3 as has been reported in young WKY rats. G(s)alpha mediates, in part, the inhibitory effect of D(1)-like agonists on NHE3 activity. In WKY rats, fenoldopam increased G(s)alpha/NHE3 binding to the same extent in 2-wk-old (1.5-fold, n = 4) and adult (1.5-fold, n = 4) rats. In contrast, in SHRs, fenoldopam decreased the amount of G(s)alpha bound to NHE3 in 2-wk-old SHRs and had no effect in 4-wk-old and adult SHRs. These studies indicate that the decreased inhibitory effect of D(1)-like agonists on NHE3 activity in SHRs (compared with WKY rats) precedes the development of hypertension. This may be caused, in part, by a decreased interaction between G(s)alpha and NHE3 in BBM secondary to impaired D(1)-like receptor function.

Aging↗
PubMed2001

Whole genome amplification increases the efficiency and validity of buccal cell genotyping in pediatric populations.

The collection of buccal cells provides a noninvasive method for obtaining DNA for genetic studies. Here we report the results on buccal cell genotyping from our ongoing study of childhood leukemia in Northern California. We have collected buccal samples from children ranging in age from 4 months to 15 years using an interviewer- or nurse-administered protocol using a cytology brush. Initial results of the genotyping, including the glutathione S-transferase mu, glutathione S-transferase theta, NAD(P)H:quinone oxidoreductase, and methylenetetrahydrofolate reductase polymorphisms, were disappointing because many specimens contained little DNA, failed repeated attempts at PCR amplification, and produced unreliable results. Here we evaluate a solution to the problem that involves whole genome amplification using the improved primer extension preamplification methodology. Sixty cases of pediatric acute leukemia were studied; five PCR-based genotypes were attempted using buccal cell DNA and whole genome amplified (WGA) buccal DNA. Results were compared with genotyping results using DNA isolated from peripheral whole blood or bone marrow for each child. The standard buccal protocol failed to yield successful PCR reactions in 30-57% of specimens, whereas WGA-buccal was markedly more efficient (2-5% failed PCR). A success rate of 100% was achieved with one repeat test of the failed WGA-PCR reactions. Misclassification of genotype was common for the glutathione S-transferase theta marker using the standard buccal procedure. The WGA-buccal protocol, however, produced genotyping results fully concordant with the referent blood or bone marrow DNA results for all five loci. DNA yields were increased by WGA to allow for approximately 900 PCR reactions/brush. WGA is very useful for improving the efficiency and validity of PCR-based genotyping in pediatric populations.

Adolescent↗
PubMed2001

[Detection of positive-strand of transfusion transmitted virus fragment in the liver of cryptogenic hepatitis].

OBJECTIVE: To evaluate whether transfusion transmitted virus (TTV) replicates in the liver and to analyze the relationship between TTV and cryptogenic hepatitis. METHODS: A 3.2 kb TTV fragment was detected by nested polymerase chain reaction (PCR) in 31 serum samples of patients with cryptogenic hepatitis who came from a school where was in an outbreak area of cryptogenic hepatitis during 1996 and in 30 healthy individuals. A hybridization/nuclease protection assay was used to detect positive-strand TTV fragment from the liver specimens of the 7 patients. RESULTS: TTV DNA was detected in serum samples from 30 of 31 (96.9%) patients and from 18 of 30 (60%) healthy individuals, respectively. There was significant difference in the prevalence of TTV infection between the two groups. Based on hybridization/ nuclease protection assays, we detected positive-strand TTV fragment in all of 7 liver specimens of the patients. CONCLUSIONS: TTV is related possibly to cryptogenic hepatitis. TTV can replicate in the liver. Although TTV only causes mild liver damage, a few patients will suffer from chronic hepatitis.

Adult↗
PubMed2001

[Characteristics of APC gene mutations in colorectal tumors].

OBJECTIVE: To investigate the mutational features of adenomatous polyposis coli (APC) gene and their possible arising mechanism in colorectal tumors. METHODS: PCR-based IVSP assay (in vitro synthesized protein test) and sequence analysis were used to determine somatic mutations of whole APC gene in 115 cases with non familial adenomatous polyposis(non-FAP) colorectal tumors. RESULTS: Seventy-six mutated cases with 101 mutations were confirmed in the study. Analysis of the spectra of APC mutations revealed that frameshift mutations were more common than point ones(56% vs 44%), ninety-one percent of them being insertions/deletions of 1-2 bp, particularly single A (61%) and 51% of point mutations locating at CpG sites. In comparison with sporadic tumors, hereditary nonpolyposis colorectal cancer (HNPCC) was found to have more frameshift mutations (69% vs 52%, P<0.05), less point mutations at CpG site (31% vs 50%, P<0.05), and a slightly lower frequency of mutations(53% vs 67%, P>0.05). There was no difference in mutational distribution of segment 3 between them (38% vs 46%, P>0.05). It was also found that 15 cases(20%) had double mutations with distance ranging from 7 to 1443 bp, suggesting the coexistance of allelic and non-allelic mutations. CONCLUSION: Based on the mutational spectra of APC gene in colorectal tumors, it can be concluded that most of gene mutations are probably related to DNA mismatch repair deficiency, and the APC mutational patterns of HNPCC and sporadic tumors are quite different. The reason of coexistance of allelic and non-allelic mutations needs to be investigated.

Colorectal Neoplasms↗
PubMed2001

Differential expression of various cytokine and chemokine genes between proliferative and non-proliferative glomerulonephritides.

BACKGROUND: Intraglomerular cellular proliferation is one of the major determinants for dividing various glomerulonephritis (GN) into two groups, such as proliferative versus non-proliferative. Cytokines and chemokines are involved in the pathogenetic pathways and would affect the functional and histologic sequelae. We hypothesized that the morphological difference might be based on the differential intrarenal expression of various cytokines and chemokines. We quantified the intrarenal gene expression of various cytokines and chemokines, and correlated it with clinical parameters. METHODS: Total RNA was extracted from 54 proliferative GN (PGN) core biopsy specimens and 42 non-proliferative GN (NPGN) specimens. Using the internal competitors, RT-PCR was instituted to quantify mRNAs. RESULTS: The magnitude of the gene expressions of IL-2, IFN-gamma, and IFN-gamma/IL-10 ratio were significantly higher in PGN than in NPGN. RANTES and IL-8 had more abundant gene messages in PGN. It was shown that Th1 cytokine was upregulated if GN was mediated by immune complexes regardless of cellular proliferation. But chemokines had the elevated levels of expression in PGN among immune complex-mediated GN. Up-regulation of the IFN-gamma/IL-10 ratio and TNF-alpha was associated with poor renal function at the time of biopsy. Renal tissues from the patients with a non-nephrotic range of proteinuria showed abundant messages for proinflammatory cytokines and chemokines. CONCLUSION: Th1, proinflammatory cytokines, and chemokines were more abundant in proliferative GN, and correlated with unfavorable clinical parameters. We propose that the clinical manifestations and diverse histologic features of human GN are associated with differential expressions of specific cytokines and chemokines.

Adolescent↗
PubMed2001

A novel serine protease SNC19 associated with human colorectal cancer.

OBJECTIVE: To study the structure and function of a novel serine protease gene associated with human colorectal cancer SNC19. METHODS: The cDNA sequence was determined by both manual and automatic sequencing techniques. The full length cDNA sequence was obtained by the 5'-Rapid Amplification of cDNA Ends technique and web-based analysis. Open reading frame analysis and protein function prediction were also performed. Northern blot was used to detect the expression of SNC19 in various human normal tissues and tumor cell lines. Fluorescent in situ hybridization combined with fluorescent R-banding technique was employed to map the SNC19 gene on human chromosome. RESULTS: Full length SNC19 cDNA, size 3152 bp, encodes a protein highly homologous to a mouse serine protease epithin. In normal human tissues, high SNC19 expression levels were observed in the kidney, pancreas, prostate, small intestine and colon; moderate SNC19 expression levels were observed in the placenta, lung, liver, spleen thymus, testis and peripheral blood lymphocytes; and extremely low expression levels were observed in the heart, brain, skeletal muscle and ovary. In tumor cell lines, colorectal cancer cells SW480, SW620, SW1116 and Colo205, breast cancer cell Bcap37 and gastric cancer cells MKN28 and SGC7901 showed high levels of SNC19 expression; cervical cancer cell HeLa-S3, lung cancer PAA, oral epithelial cancer cell KB and lymphoma cell Raji showed moderate levels of SNC19 expression; and tongue squamous cancer cell Tca8113, leukemia cells HL-60, K562, MOLT-4, lung cancer cell A549 and melanoma cell G361 showed very low levels of SNC19 expression. SNC19 was mapped to human chromosome 11q24-25. CONCLUSION: SNC19 encodes a novel human serine protease with 855 amino acid residues. As a novel serine protease associated with human colorectal cancer, the expression of SNC19 in various tissues and cell lines may have very important impact on their phenotypes and biological behaviors.

Amino Acid Sequence↗
PubMed2001

[The effects of nifedipine on proliferation and DNA synthesis of gingival fibroblasts].

OBJECTIVE: To investigate the effects of nifedipine, a calcium channel blocker, on cellular proliferation in gingival fibroblasts in vitro. METHODS: Gingival fibroblasts were cultured and incubated with various concentrations of nifedipine (1,200.0, 360.0, 108.0 and 32.4 micrograms/L) for up to 7 days. H-TdR incorporation assay in vitro taken was used to evaluate the amount of DNA synthesis. RESULTS: Cell numbers were significantly different among these groups on sixth and seventh day, especially higher in 1,200.0 micrograms/L and 360.0 micrograms/L groups. The incorporation percentage in high concentration groups were significantly higher than those in others. CONCLUSION: Nifedipine can influent proliferation of gingival fibroblasts in high concentration.

Adolescent↗
PubMed2001

[Treatment of ion-exchange monosodium glutamate wastewater by yeast].

Two strains of yeasts, Candida halophila and Rhodotorula glutinis, were acquired through screening from ion-exchange monosodium glutamate wastewater (IEMGW) which was characterized by its high contents of COD (40,690 mg/L), NH(4+)-N (16,914 mg/L) and SO(4)2- (18,000 mg/L). The mixture of the two species had a good COD removal performance for treating IEMGW in a pH rang of 4-9. The yeast technology was superior to the conventional activated sludge in terms of COD removal and COD decomposition rate, In a dilution rate range of wastewater from 1:1 to 1:9, a COD removal of 84.5% and an average COD decomposition rate of over 1.0 kg/(kg.d) were obtained under an initial pH of 4.

Candida↗
PubMed2001

[Localization and analysis of 1A6 gene by dual-color fluorescence in situ hybridization on gastric carcinoma tissue and tumor cell lines].

OBJECTIVE: To locate 1A6 gene on the chromosome and study its copy number by dual-color fluorescence in situ hybridization (FISH) on three tumor cell lines and 22 gastric tumors patients. METHODS: The single-color FISH of small size biotin-labeled cDNA cloned in plasmid was used to locate the 1A6 gene on one of the chromosomes in C group. Genomic DNA of 1A6 gene was screened by polymerase chain reaction (PCR) in PAC library according to the sequence. The florenscence of green and orange was incorporated into the target gene-1A6 cloned in PAC and chromosome-12-specific alpha-satellite repeat DNA by nick translation, followed by dual-color FISH. 1A6 gene was located in the metaphase chromosome of the normal peripheral lymphocytes. 1A6 gene and chromosome 12 copy numbers were analyzed on touch slide of gastric cancer tissue and cell lines. RESULTS: 1A6 gene was located in 12q23.2-23.3. The chromosome 12/1A6 signal ratio was 0.96-1.01 in breast, ovarian and gastric cancer cell lines. The ratio was 0.93-1.11 in gastric cancer tissue touch slides. The number of chromosome 12 is disomic (87.7%), triploid (7.4%) in BMI cell line; multisomic(100%), including pentasomic (67.6%) in SKOV3; the multisomic (83.1%), including trisomic (71%) in SGC823. There are highly disomic rate in 86. 4% (19/22) of patients. CONCLUSION: 1A6 gene is in 12q23.2-23.3. Neither 1A6 amplification nor deletion in gastric cancer tissue and three cell lines was found. Further study is needed for the understanding of chromosome 12 copy number variation in different cancer cell lines.

Chromosome Mapping↗
PubMed2001

[Analysis of group composit of crude oil by on-line coupling of capillary HPLC-HTGC].

The group composition of crude oil was analyzed by on-line coupled capillary HPLC-HTGC. After removal of asphaltenes, the oil sample was separated by capillary HPLC into aliphatics, aromatics and resins. The interface cut and stored each fraction, and transfered them into GC sequentially. The group contents of oil were determined by FID. The error of reproducibility(RSD) was less than 3%. The method is accurate, time saving, and easy for operation. It is very important for quality control and development of new and better products in crude oil.

English Abstract↗