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Y Ma

Publications and source records attributed to Y Ma.

At least 199 records · Page 11Linked to original sources
PubMed2000

Cell type-specific regulation of fetal fibronectin expression in amnion: conservation of glucocorticoid responsiveness in human and nonhuman primates.

The appearance of oncofetal fibronectin (FFN) in cervical and vaginal secretions is predictive of human labor. Levels of FFN in amnion increase with the onset of labor in rhesus monkeys. Since glucocorticoid (GC) levels in serum and amniotic fluid increase in association with parturition, we compared GC-mediated regulation of FFN expression in cultures of amnion epithelial cells and fibroblasts isolated from human and baboon amnions. Cells were maintained with and without dexamethasone (DEX), and levels of FFN in the conditioned media were determined by ELISA. We observed that DEX treatment suppressed FFN levels in both human and baboon amnion epithelial cells, whereas it increased FFN levels in amnion fibroblasts. DEX treatment reduced FFN levels in cytotrophoblasts from human placenta and increased FFN levels in placental fibroblasts. Northern blots revealed that DEX reduced levels of fibronectin (FN) mRNA in amnion epithelial cells and cytotrophoblasts, whereas it increased FN mRNA in amnion and placental fibroblasts. We conclude that GC differentially regulates FFN expression in epithelial and mesenchymal cells from amnion and placenta. In addition, this pattern of cell type-specific FFN regulation by GC is conserved in human and nonhuman primates and may be responsible for parturition-dependent changes in FFN expression in gestational tissues.

Amnion↗
PubMed2000

Histology of the gastroesophageal junction: an autopsy study.

Current diagnostic criteria for reflux disease and Barrett's esophagus are based on the belief that the gastroesophageal junction normally contains 2 cm of cardiac mucosa composed of mucous glands devoid of parietal cells. This autopsy study disproves this belief. Even when the entire circumference of the gastroesophageal junction is examined, pure cardiac mucosa was completely absent in 56% of patients. All patients had oxyntocardiac mucosa, in which glands contained a mixture of mucous and parietal cells. Cardiac and oxyntocardiac mucosae were present only in part of the circumference of the junction in 50% of patients. The measured maximum length of cardiac plus oxyntocardiac mucosa was less than 0.5 cm in 76% of patients. There was a tendency for the presence and extent of cardiac mucosa to increase with age. Cardiac mucosa at the junction is therefore frequently absent, has considerable individual variation, is very small in extent when present, is commonly absent from some part of the circumference of the junction, and increases in prevalence and length with age. These characteristics of cardiac mucosa make it highly unlikely that it is a normal structure. We develop the hypothesis that cardiac mucosa represents an early histologic manifestation of gastroesophageal reflux.

Adolescent↗
PubMed2000

Seroprevalence and risk factors of hepatitis B, hepatitis C, and human cytomegalovirus among HIV-infected and high-risk uninfected adolescents: findings of the REACH Study. Adolescent Medicine HIV/AIDS Research Network.

BACKGROUND AND OBJECTIVES: In adolescents and young adults, multiple studies have identified sexual activity and behaviors as significant risk factors for acquiring both human cytomegalovirus (HCMV) and hepatitis B virus (HBV). However, there are no reports on the prevalence or risk factors for infection of these viruses and hepatitis C virus (HCV) in an adolescent population with sexually acquired HIV. GOALS: To examine the seroprevalence and risk factors of HBV, HCV, and HCMV infection in a population of HIV-infected male and female adolescents and in an age- and risk behavior-matched HIV-uninfected cohort. STUDY DESIGN: A cross-sectional analysis of HBV, HCV, and HCMV infections in a cohort of HIV-infected and HIV-uninfected adolescents. RESULTS: Adolescent males infected with HIV were more likely to have evidence of HBV and HCMV infection than HIV-uninfected males (23.7% versus 0%, respectively, for HBV, P = 0.008; 79.7% versus 50%, respectively, for HCMV, P = 0.004). HIV-infected females were more likely to have evidence of HCMV infection (78.5% versus 61.4%, P = 0.003) than HIV-uninfected females. No significant difference was found for HBV infection in the two groups of females. The rate of HCV infection (1.6%) was too small to make comparisons between the groups. To determine whether the differences in infection rates for HBV and HCMV could be explained by factors other than HIV status, a variety of possible risk factors were examined using univariate and multivariate analyses. A significant risk factor for HBV and HCMV infections for males was a homosexual or bisexual orientation. For females, a risk factor for HBV infection was having more than 10 lifetime sexual partners; for HCMV infection, HIV infection was the only risk factor. In addition, in the HIV-infected cohort, 15% of females and 36% of males who were seropositive for HBV had evidence of active HBV infection. CONCLUSIONS: These results emphasize the need for continued development of primary and secondary prevention programs and clinical screening and treatment for HBV and HCMV in adolescents.

Adolescent↗
PubMed2000

Characterization of Micrococcus antarcticus sp. nov., a psychrophilic bacterium from Antarctica.

A Gram-positive, cold-adapted, aerobic, spherical actinobacterium (strain T2T) with a quite low cardinal growth temperature was isolated from Chinese Great-Wall station in Antarctica. Sequence comparisons of the 16S rDNA indicated the isolate to be a phylogenetic member of the genus Micrococcus, family Micrococcaceae, in which it represents a novel lineage. The phylogenetic distinctness of the isolate with respect to the type strains Micrococcus luteus and Micrococcus lylae was supported by DNA-DNA similarity values of less than 40%. Chemotaxonomic properties supported the placement of the isolate in the genus Micrococcus. The diagnostic diamino acid of the cell-wall peptidoglycan is lysine. The predominant menaquinones are MK-8 and MK-8(H2). The G + C content of the DNA of the isolate is 66.4 mol%. Genotypic, morphological and physiological characteristics were used to describe a new species of Micrococcus, for which the name Micrococcus antarcticus is proposed. The type strain is T2T (= AS 1.2372T).

Amino Acids↗
PubMed2000

Most retroviral recombinations occur during minus-strand DNA synthesis.

Retroviral RNA molecules are plus, or sense in polarity, equivalent to mRNA. During reverse transcription, the first strand of the DNA molecule synthesized is minus-strand DNA. After the minus strand is polymerized, the plus-strand DNA is synthesized using the minus-strand DNA as the template. In this study, a helper cell line that contains two proviruses with two different mutated gfp genes was constructed. Recombination between the two frameshift mutant genes resulted in a functional gfp. If recombination occurs during minus-strand DNA synthesis, the plus-strand DNA will also contain the functional sequence. After the cell divides, all of its offspring will be green. However, if recombination occurs during plus-strand DNA synthesis, then only the plus-strand DNA will contain the wild-type gfp sequence and the minus-strand DNA will still carry the frameshift mutation. The double-stranded DNA containing this mismatch was subsequently integrated into the host chromosomal DNA of D17 cells, which were unable to repair the majority of mismatches within the retroviral double-strand DNA. After the cell divided, one daughter cell contained the wild-type gfp sequence and the other daughter cell contained the frameshift mutation in the gfp sequence. Under fluorescence microscopy, half the cells in the offspring were green and the other half of the cells were colorless or clear. Thus, we demonstrated that more than 98%, if not all, retroviral recombinations occurred during minus-strand DNA synthesis.

Cell Line↗
PubMed2000

Sequencing a specific kinetoplast DNA fragment of Leishmania donovani for polymerase chain reaction amplification in diagnosis of leishmaniasis in bone marrow and blood samples.

A set of oligonucleotide primers I and II was developed by analyzing the specificity of a cloned kinetoplast DNA (kDNA) fragment of Leishmania donovani and sequencing the fragment. Polymerase chain reaction (PCR) was conducted with the primers to amplify a minicircle kDNA fragment (297 bp) to detect L. donovani in the bone marrow (22 samples), whole blood (16 samples), and serum (17 samples) of 22 patients with visceral leishmaniasis. All of 22 patients were diagnosed by microscopic identification. Control samples of bone marrow, whole blood, and serum were obtained from patients with leukemia and from healthy volunteers. In addition, 12 dogs were infected with L. donovani promastigotes for the PCR test. The total number of patients positive by PCR testing was 95.5% (21/22), with 91.0% (20/22) from the bone marrow, 68.8% (11/16) from the blood, and 29.4% (5/17) from the sera. Similar results were obtained in infected dogs. No amplification products were seen in control samples from humans or dogs. Our results suggest that PCR may be useful in detecting kDNA in the bone marrow and blood of patients with visceral leishmaniasis.

Animals↗
PubMed2000

Effects of somatic cell count on quality and shelf-life of pasteurized fluid milk.

Milk was collected from eight Holstein cows four times before and four times after intramammary infection with Streptococcus agalactiae. Postinfection milk had significantly higher somatic cell count (SCC) (849,000 cells/ml) than preinfection milk (45,000 cells/ml). High SCC raw milk had more lipolysis and proteolysis than low SCC raw milk. Pasteurized, homogenized, 2% fat milks from pre- and postinfection periods were stored at 5 degrees C and analyzed for lipolysis, proteolysis, microbial quality, and sensory attributes at 1, 7, 14, and 21 d post processing. During refrigerated storage, the average rates of free fatty acid increase (i.e., lipolysis) and casein hydrolysis in high SCC milk were, respectively, three and two times faster than those in low SCC milk. In general, standard plate counts, coliform counts, and psychrotrophic bacterial counts of both the high and low SCC milks remained low (<100,000 cfu/ ml) during 5 degrees C storage. Low SCC milk maintained high organoleptic quality for the entire 21-d shelf-life period. However, for high SCC milk, between 14 and 21 d, sensory defects were detected, which resulted in low overall quality ratings. The sensory defects mainly included rancidity and bitterness and were consistent with higher levels of lipolysis and proteolysis. Hence, mastitis adversely affected the quality of pasteurized fluid milk. It is recommended that the fluid milk industry consider implementation of premium quality payment programs for low SCC milks.

Animals↗
PubMed2000

Gravity separation of raw bovine milk: fat globule size distribution and fat content of milk fractions.

This project determined effects of time and temperature on changes of fat globule size distribution and fat content in milk fractions during gravity separation. Fresh raw bovine milk was gravity separated at 4 or 15 degrees C. After 2, 6, 12, and 48 h, seven fractions, from bottom fraction (F1) to top fraction (F7), were successively drained from a separation column. Higher temperature resulted in a faster rate of fat separation. Within 2 h, large fat globules had already moved to the top, and the volume mean diameter of F7 increased from 3.13 microm (without separation) to 3.48 and 3.64 microm, respectively, at 4 and 15 degrees C. In F7, there was little change in globule size distribution after 2 h, but fat content continued to increase with separation time. The fat content of F7 reached 26.6% after 48 h at 4 degrees C, achieving a 58.8% creaming capacity. For F1 to F6, longer separation time resulted in smaller fat globule sizes and lower fat contents, especially for F1. After 48 h at 4 degrees C, the volume mean diameter of F1 decreased from 3.23 microm (without separation) to 1.16 microm, and fat content decreased from 3.75% (without separation) to 0.20%. Gravity separation may have unique applications in the dairy industry today. Its simplicity makes it an effective procedure for small-scale dairy product manufacturers to produce milks with a range of fat contents without using a centrifugal cream separator.

Animals↗
PubMed2000

Expression of vascular endothelial growth factor in liver tissues of hepatitis B.

OBJECTIVE: To study the relationship between vascular endothelial growth factor (VEGF) and grading (G) and staging (S) of hepatitis B (HB). METHODS: Immunohistochemical staining was performed with VEGF monoclonal antibody in 250 biopsies of HB. RESULTS: The types of VEGF expression in liver tissues were of plasma type, sinusoidal membrane type and sinusoidal endothelial cell type. VEGF was mainly secreted by hepatocytes, and was also positively expressed in liver sinusoidal endothelial cells, fat-storing cells, myofibroblast and monomorphological nuclear cells. And it was negative in vascular endothelial cells and hepatocytes which had not significant damage, suggesting that the expression of VEGF was enhanced with the increase of G (chi(2)=90.43, P<0.01). VEGF was positively expressed on those whose scores of S were lower, while strongly positively expressed on those whose scores of S were higher. There was also a significant difference between them (chi(2)=115.74, P<0.01). CONCLUSION: The expressions of VEGF are related to G and S of HB

Endothelial Growth Factors↗
PubMed2000

[Disorders of hepatic sinusoids and perisinusoidal space in chronic viral hepatitis B and its relationship to hepatic fibrosis].

OBJECTIVE: To explore the disorders of the hepatic sinusoids and perisinusoidal space in chronic viral hepatitis B and its relationship to hepatic fibrosis. METHODS: The histopathology, the expression of smooth muscle actin (SMA), fibronectin (FN), laminin (LN) and collagen type IV (C-IV), and deposition of reticular, collagenous and elastic fibers in the sinusoids and perisinusoidal space in 160 liver biopsy specimens of viral hepatitis B were examined by haematoxyln and eosin (HE), immunohistochemistry and special stains techniques, respectively. RESULTS: The pathological changes of the hepatic sinusoids were collapsing, expansive, occlusive and narrowing. The changes in SMA distribution were characteristic. The spotty activated stellate cells were proliferating, transiting, expressing SMA, and stretching down the wall of sinus or forming fine bundles in G(1) or G(2); they were more active in proliferation, transition, forming bridging and even wide fibrous septa constituted by myofibroblast cells in G(3) or G(4). The other 3 elements, FN, IV-C, LN and reticular, collagenous and elastic fibers deposited in the sinusoids and perisinusoidal space following SMA. The higher the gradings were, the more the depositing elements were. They mainly deposited in the areas of degeneration, inflammation, necroses and fibrous bundles (septa) where the pathologic changes of sinusoids happened. CONCLUSION: The sinusoids and perisinusoidal space is the original sites of fibrosis. Special attention should be paid to the pathological changes in the sinusoids and perisinusoidal space when to evaluate the gradings of histopathology and stagings of hepatic fibrosis.

Actins↗
PubMed2000

[The adsorption on attapulgite and cross-linked agar beads entrapped attapulgite(CAA)].

The adsorption of four drugs with certain toxicity, i.e. chlorpromazine, quinidine, diazepam and phenobarbital on attapulgite and Cross-linked Agar Beads Entrapped Attapulgite(CAA) was determined in this study. The results revealed that attapulgite possessed high adsorption for the cation drugs(chlorpromazine and quinidine), moderate adsorption for diazepam, and slight adsorption for phenobabital. The adsorption in attapulgite was quite quick and came to equilibrium in about 30 min. No significant difference(P > 0.05) of adsorption on attapulgite was observed at 30 min and 60 min. The adsorbent selectivity on CAA was the same as that on attapulgite. The speed of the adsorption was slower on CAA than on attapulgite, but the quantity adsorpted on CAA and that on attapulgite had no marked difference(P > 0.05) after 60 min. CAA preserved the adsorption property of attapulgite fundamentally. CAA overcame the dispersibility of attapulgite distinctly and showed good hemocompatibility and a fair blood flow rate in hemoperfusion. It may play an important role in the separation of blood components and in hemopurification.

Adsorption↗
PubMed2000

[The characteristics of clinical course of chronic hepatitis B and liver cirrhosis pathology of child patient].

OBJECTIVE: To study the characteristics of clinical course of chronic hepatitis B and liver cirrhosis pathology of the child patients. METHODS: The serum test for hepatitis A/B/C/E, the liver function test and the liver puncture for pathological examination were performed in 66 child patients with chronic hepatitis B. RESULTS: The age, clinical course and form of disease onset, showed no-obvious difference between S0 group (without liver cirrhosis) and group > or = S3 (with evident liver cirrhosis). The cases with splenomegaly accounted for 2.9% in S0 group, but 32.3% in group > or = S3. The Hbe Ag positive rate of group S0 was apparently higher than that of group > or = S3 (74.29% and 29.03%, respectively). The higher the activity of liver inflammation, the more serious the extent of liver cirrhosis. CONCLUSIONS: The liver cirrhosis of child patients with chronic hepatitis B has nothing to do with their age, clinical course, form of disease onset and virus replication, but it is in direct connection with the liver inflammation activity. If splenomegaly occurs and thrombin acts abnormally, albumin in serum decreases while gamma-globulin increases, the liver cirrhosis should be highly watched out for.

Alanine Transaminase↗
PubMed2000

[An investigation on gynecology of 29 generations of Zheng's medical family in Kunshan].

Passing through different dynasties of Song, Yuan, Ming, Qing and Republican period, the Zheng's medical family of Kunshan, Jiangsu, specialized in gynecology has a history of nearly 800 years, 29 generations, being a rare miracle in world medical history and parallel with the He's family of Jiangnan, also a medical family of 29 generations. This paper, by making use of written materials including geneological tree, epitaph, local annals, medical works and manuscripts, summarizes the genecoloyg, biographies, medical know-how, and medical works, of Zheng's family, and draws illustration for the geneological tree of the family.

China↗
PubMed2000

[Horizontal thermal characteristics at forest edge in calm tropical region of China].

The temperature measurement at southwest-facing edge of a rubber forest was conducted in a calm tropical region of Xishuangbanna, Yunnan, China in January 1998, and the daytime thermal characteristics and their time-space variations nearby the edge of the rubber forest were discussed. There was an obviously thermal effect at forest edge. The depth of edge influence on soil surface temperature was up to 13 m from the edge into the forest. Soil surface temperature reached its highest at 4.5 m outside the forest. The highest air temperature occurred at 0 m of the edge. The heat transfer nearby the edge was quite different in number and in direction. Outside the forest, the heat was transferred from ground to air on almost daytime, while at interior of forest, was opposite after the noon. The heat was transferred from the rubber canopy to the ground. At the forest edge, such variation was complex, depended mainly on location and time.

China↗
PubMed2000

[Interaction of Se and S forms in rhizospheric soil and their absorption by tobacco].

Pot experiment with tobacco shows that the amount of total, solube, exchangeable and organic Se in rhizospheric soil appeared depletory, while that of total, adsorbed and organic S appeared enriched. The influence of added S on Se depletion depended on the level of Se application, and that of added Se on S enrichment depended on the rate of S applicagtion. In the absence of added Se, the addition of S decreased the depletion of several Se forms; while in its presence, the reverse result was obtained. The addition of Se increased the enrichment of total S when the S was not added. With S application, the added Se reduced the enrichment of total S. At early stage, teh Se content of tobacco was mainly influenced by the soluble Se in rhizospheric soil, while the accumulated amount of Se in tobacco was also influenced by exchangeable, organic and acid soluble Se. The S content in the aboveground part of tobacco at its early stage was mainly influenced by soluble and organic S in the rhizosphere.

Absorption↗
PubMed2000

Co-modification of IL-2-TNF alpha fusion gene and B7.1 gene to murine breast tumor cells leads to improved tumor rejection and vaccine effect.

OBJECTIVE: To improve the vaccine potency of gene-modified tumor cells. METHODS: Using recombinant adenoviruses, we expressed the B7.1 gene in murine breast tumor cell line EMF6 and a subline previously transfected with retrovirus vector XdF harboring the IL-2-TNF alpha fusion gene. RESULTS: Immunization/challenge experiments demonstrated that IL-2-TNF alpha/B7.1 co-modified tumor cells possessed a lower tumorigenicity in vivo and an improved tumor-specific vaccine potency compared with single gene transfectant (P < 0.05). Three weeks after immunization with a variety of tumor cells, the mixed lymphocyte and tumor cells reaction assay (MLTB) and 51Cr-release assay were performed to test cellular immunity function. The results indicated that IL-2-TNF alpha and B7.1 together induced a more potent antitumor immune response than either molecule alone, 25% higher than IL-2-TNF alpha and 20% higher than B7.1, respectively. CONCLUSION: The IL-2-TNF alpha fusion gene and B7.1 gene act in concert to improve their antitumor effectiveness.

Animals↗
PubMed2000

[Study on perinatal group B Streptococcus carriers and the maternal and neonatal outcome].

OBJECTIVE: To investigate the group B streptococcus (GBS) colonization rate and the relationship between vaginal colonization of GBS and the maternal and neonatal outcome. METHODS: 3% TH selective broth media were used for culture of GBS. The vaginal samples were collected during different pregnant periods (before 20 weeks' gestation; 20-28 weeks; after 34 weeks' gestation) and other samples from different sites after labor (including neonatal throat, ear, umbilicus and placenta, umbilical blood, maternal blood, etc). RESULTS: The GBS carrier rate in 1 039 pregnant women was 11.07% (115/1,039). The colonization rate of different treating times was 29.73% (test three times), 15.50% (test twice) and 9.86% (test one time) respectively. The carrier rate of three-time-test was significantly higher than that of two times test (P < 0.01) and that of only one time (P < 0.01). The carrier rate in three periods was 16.84% (< 20 weeks), 18.40% (20-28 weeks) and 14.90% (> 34 weeks) respectively. Obstetric complications associated with GBS carrier were similar with those of non-carrier. Neonatal carrier rate was 9.95%. The neonatal carrier rate in the group of carrier mothers was higher than that of non-carrier mothers (14.29%:7.26%). The rate of neonatal pneumonia and the upper respiratory tract infection in GBS-carrier-mother was higher than that of non-carrier mothers (11.01%:9.71%; 8.27%: 6.07%) while it was similar in neonatal carrier group and non-carrier group (20.00%:14.92%; 10.00%:4.97%). CONCLUSION: GBS might be one of vaginal pathogens in Chinese women, but it is not severe enough to threaten the health of pregnant women and their newborns.

Carrier State↗