Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 307 records · Page 17Linked to original sources

PubMed2000

Id-2 regulates critical aspects of human cytotrophoblast differentiation, invasion and migration.

During early human placental development, the conceptus attaches itself to the uterus through cytotrophoblast invasion. Invasive cytotrophoblast cells differentiate from precursor villous cytotrophoblasts, but the essential regulating factors in this process are unknown. Basic helix-loop-helix (bHLH) transcription factor dimers are essential regulators of mouse trophoblast development. We therefore examined the importance of this family of factors in the human placenta. In many cell lineages, bHLH factors are sequestered by members of the Id family, HLH proteins that lack the basic DNA binding domain (Inhibitor of DNA binding proteins (Id-1 to Id-4)). During differentiation of some tissues, Id expression declines, allowing bHLH factors to dimerize, bind DNA and trans-activate lineage-specific genes. To begin to study the role of bHLH transcription factors in human placental development, we first characterized Id expression in cytotrophoblast cells. The cells expressed Id-3 constitutively; Id-2 was downregulated, at the mRNA and protein levels, as the cells differentiated in culture and in situ, respectively. In cases when cytotrophoblast differentiation was compromised (in placentas from women with preeclampsia, or in cells grown under hypoxic conditions in culture), Id-2 expression was maintained. To assess the functional relevance of these correlations, we used an adenovirus vector to maintain Id-2 protein expression in cultured cytotrophoblasts. Compared to control (lacZ-expressing) cells, cytotrophoblasts transduced to constitutively express Id-2 retained characteristics of undifferentiated cells: (alpha)1 integrin expression was low and cyclin B expression was retained. Furthermore, invasion through Matrigel was partially inhibited and migration was strikingly enhanced in Id-2-expressing cells. These results suggest that Id-2 and the bHLH factors that it partners play important roles in human cytotrophoblast development.

Animals↗

PubMed2000

Regulation of the UNC-5 netrin receptor initiates the first reorientation of migrating distal tip cells in Caenorhabditis elegans.

Cell migrations play a critical role in animal development and organogenesis. Here, we describe a mechanism by which the migration behaviour of a particular cell type is regulated temporally and coordinated with over-all development of the organism. The hermaphrodite distal tip cells (DTCs) of Caenorhabditis elegans migrate along the body wall in three sequential phases distinguished by the orientation of their movements, which alternate between the anteroposterior and dorsoventral axes. The ventral-to-dorsal second migration phase requires the UNC-6 netrin guidance cue and its receptors UNC-5 and UNC-40, as well as additional, UNC-6-independent guidance systems. We provide evidence that the transcriptional upregulation of unc-5 in the DTCs is coincident with the initiation of the second migration phase, and that premature UNC-5 expression in these cells induces precocious turning in an UNC-6-dependent manner. The DAF-12 steroid hormone receptor, which regulates developmental stage transitions in C. elegans, is required for initiating the first DTC turn and for coincident unc-5 upregulation. We also present evidence for the existence of a mechanism that opposes or inhibits UNC-5 function during the longitudinal first migration phase and for a mechanism that facilitates UNC-5 function during turning. The facilitating mechanism presumably does not involve transcriptional regulation of unc-5 but may represent an inhibition of the phase 1 mechanism that opposes or inhibits UNC-5. These results, therefore, reveal the existence of two mechanisms that regulate the UNC-5 receptor that are critical for responsiveness to the UNC-6 netrin guidance cue and for linking the directional guidance of migrating distal tip cells to developmental stage advancements.

Animals↗

PubMed2000

Genetic determination of Colles' fracture and differential bone mass in women with and without Colles' fracture.

Osteoporotic fractures (OFs) are a major public health problem. Direct evidence of the importance and, particularly, the magnitude of genetic determination of OF per se is essentially nonexistent. Colles' fractures (CFs) are a common type of OF. In a metropolitan white female population in the midwestern United States, we found significant genetic determination of CF. The prevalence (K) of CF is, respectively, 11.8% (+/- SE 0.7%) in 2471 proband women aged 65.55 years (0.21), 4.4% (0.3%) in 3803 sisters of the probands, and 14.6% (0.7%) in their mothers. The recurrence risk (K0), the probability that a woman will suffer CF if her mother has suffered CF is 0.155 (0.017). The recurrence risk (Ks), the probability that a sister of a proband woman will suffer CF given that her proband sister has suffered CF is 0.084 (0.012). The relative risk lambda (the ratio of the recurrence risk to K), which measures the degree of genetic determination of complex diseases such as CF, is 1.312 (0.145; lambda 0) for a woman with an affected mother and 1.885 (0.276; lambda s) for a woman with an affected sister. A lambda-value significantly greater than 1.0 indicates genetic determination of CF. The terms lambda 0 and lambda s are related to the genetic variances of CF. These parameters translate into a significant and moderately high heritability (0.254 [0.118]) for CF. These parameters were estimated by a maximum likelihood method that we developed, which provides a general tool for characterizing genetic determination of complex diseases. In addition, we found that women without CF had significantly higher bone mass (adjusted for important covariates such as age, weight, etc.) than women with CF.

Absorptiometry, Photon↗

PubMed2000

Mycelial pellet formation by Rhizopus oryzae ATCC 20344.

Factors in a cultivation medium affecting fungal growth morphology and fumaric acid production by Rhizopus oryzae ATCC 20344 were investigated. These factors included the initial pH value and trace metals such as zinc, magnesium, iron, and manganese in the cultivation medium. It was found that a significant change in the growth morphology of R. oryzae ATCC 20344 occurs when the initial pH value is varied. A lower initial pH value in the cultivation medium was inhibitory to fungal growth, and fast growth in the cultivation medium at a higher initial pH value promoted the formation of large pellets or filamentous forms. Trace metals in the cultivation media also had significant effects on pellet formation and fumaric acid fermentation.

Cations, Divalent↗

PubMed2000

Altered chicken thyroid hormone metabolism with chronic GH enhancement in vivo: consequences for skeletal muscle growth.

In contrast to most vertebrates, GH reportedly has no effect upon somatic growth of the chicken. However, previous studies employed only one to two dosages of the hormone, and limited evidence exists of a hyperthyroid response that may confound its anabolic potential. This study evaluated the effects of 0, 10, 50, 100 and 200 microgram/kg body weight per day chicken GH (cGH) (0-200 GH) infused i.v. for 7 days in a pulsatile pattern to immature, growing broiler chickens (9-10 birds/dosage). Comprehensive profiles of thyroid hormone metabolism and measures of somatic growth were obtained. Overall (average) body weight gain was reduced 25% by GH, with a curvilinear, dose-dependent decrease in skeletal (breast) muscle mass that was maximal (12%) at 100 GH. This profile mirrored GH dose-dependent decreases in hepatic type III deiodinase (DIII) activity and increases in plasma tri-iodothyronine (T(3)), with bot! h also maximal (74 and 108% respectively) at 100 GH. No effect on type I deiodinase was observed. At the maximally effective dosage, hepatic DIII gene expression was reduced 44% versus controls. Despite dose-dependent, fold-increases in hepatic IGF-I protein content, circulating IGF-I was not altered with GH infusion, suggesting impairment of hepatic IGF-I release. Significant, GH dose-dependent increases in plasma non-esterified fatty acid and glucose, and overall decreases in triacylglycerides were also observed. At 200 GH, feed intake was significantly reduced (19%; P<0.05) versus controls; however, additional control birds pair-fed to this level did not exhibit any responses observed for GH-treated birds. The results of this study support a pathway by which GH impacts on thyroid hormone metabolism beginning at a pretranslational level, with reduced hepatic DIII gene expression, translating to reduced protein (enzyme) ex! pression, and reflected in a reduced level of peripheral T(3)-degrading activity. This contributes to decreased conversion of T(3) to its inactive form, thereby elevating circulating T(3) levels. The hyper-T(3) state leads to reduced net skeletal muscle deposition, and may impair release of GH-enhanced, hepatic IGF-I. In conclusion, GH has significant biological effects in the chicken, but profound metabolic actions predominate that may confound positive, IGF-I-mediated skeletal muscle growth.

Adipose Tissue↗

PubMed2000

Evidence of a role for neuropeptide Y and monoamines in mediating the appetite-suppressive effect of GH.

Among the many responses to GH administration is suppression of voluntary feed intake (FI) in some species, attributed to improvement in the efficiency of nutrient utilization and, therefore, reduced need for ingested substrates. Commercial broiler chickens have been genetically selected for generations for rapid growth, realized largely via the major correlated response of increased voluntary feed consumption. Neuropeptide Y (NPY) and monoamines play very important roles in the central regulation of feeding. Preliminary studies from our laboratory suggest that the appetite-suppressive effect of GH may be independent of its actions as a repartitioning agent, and may involve alterations in NPY expression at the pre-translational level. The purpose of this investigation was to explore the dose-response nature of the appetite-suppressive effect of GH in juvenile broilers, and the possible involvement of NPY and monoamines in this process. A GH dose-response study was conducted using 8-week-old female broilers infused i.v. with GH in a pulsatile pattern for 7 days at 0, 10, 50, 100 or 200 microgram/kg body weight per day. Hypothalamic NPY and epinephrine (EP) concentrations decreased in a dose-related manner with GH. At the highest dosage, voluntary FI decreased 19% (P<0.05) and hypothalamic NPY mRNA decreased approximately 50% in the infundibular nuclei and midline region (P<0.0001). In contrast, birds pairfed to the high-GH dosage group did not differ from controls, verifying that changes in NPY and monoamines were not secondary to reduced FI. We conclude that hypothalamic NPY and EP are likely candidates to explore further as mediators of the appetite-suppressive effect of GH.

Animals↗

PubMed2000

Comparison of two PCR techniques used in amplification of microdissected plant chromosomes from rice and wheat.

Linker adaptor-mediated PCR (LAM-PCR) and degenerate oligonucleotide primed PCR (DOP-PCR) are major ways to generate chromosome-specific libraries. In this study, these two PCR techniques were used to amplify the microdissected mitotic and meiotic chromosomes from rice and wheat. The results of amplifications were compared, and the advantages and limitations between the two techniques are presented.

Blotting, Southern↗

PubMed2000

Fragment size difference between multiplex and singleplex PCR products and their practical implications.

By simultaneously amplifying several loci in the same reaction, multiplex PCR has been used in gene mapping and DNA typing with polymorphic short tandem repeat loci. Previous studies have discussed in detail the various parameters and conditions that influence the quantity of individual products generated by multiplex PCR. In practice, when a primer pair fails to amplify in a multiplex PCR for some individuals, singleplex PCR is often employed as a supplement to amplify the primer pair. However, the reliability of this procedure is unknown. In this study, we used six primer pairs from ABI PRISM Linkage Mapping Set version 2 to perform multiplex and singleplex reactions. The fluorescence-labeled amplification products were separated and detected on ABI PRISM 310 Genetic Analyzer. We found that for the marker D1S468, multiplex and singleplex reactions for the majority of individuals yielded reactions of different sizes. Therefore, the potential size difference between multiplex and singleplex reactions needs to be investigated. This investigation is essential to employ multiplex PCR supplemented with singleplex PCR in gene mapping and DNA typing.

DNA↗

PubMed2000

Dehydroepiandrosterone sulfate and beta-cell function: enhanced glucose-induced insulin secretion and altered gene expression in rodent pancreatic beta-cells.

Administration of dehydroepiandrosterone (DHEA), or its sulfated form (DHEAS), controls hyperglycemia in diabetic rodents without directly altering insulin sensitivity. We show that DHEAS enhanced glucose-stimulated insulin secretion when administered in vivo to rats or in vitro to beta-cell lines, without changing cellular insulin content. Insulin secretion increased from 3 days of steroid exposure in vitro, suggesting that DHEAS did not directly activate the secretory processes. DHEAS selectively increased the beta-cell mRNA expression of acyl CoA synthetase-2 and peroxisomal acyl CoA oxidase in a time-dependent manner. Although DHEAS is a peroxisomal proliferator, it did not alter the mRNA expression of peroxisomal proliferator-activated receptor (PPAR) alpha or beta, or enhance the activity of transfected PPAR alpha, beta, or gamma in vitro. Thus, DHEAS directly affected the beta-cell to enhance glucose-stimulated insulin secretion and increased the mRNA expression of specific beta-cell mitochondrial and peroxisomal lipid metabolic enzymes. This effect of DHEAS on insulin secretion may contribute to the amelioration of hyperglycemia seen in various rodent models of diabetes.

Acyl-CoA Oxidase↗

PubMed2000

Effect of reproductive status on plasma oxytocin concentrations and the renal response to oxytocin in the conscious rat.

The magnitude of diuresis and natriuretis produced by oxytocin in the female rat has been shown to be dependent on the stage of the oestrous cycle. A study has been performed to determine the role of ovarian steroids in modulating the renal response to oxytocin infused at a rate of 100 fmol min-1 in hypotonic saline. Observations were performed on ovariectomised rats with and without steroid treatment and rats with suppressed oestrous cycles following treatment with the long-acting gonadotrophin-releasing hormone analogue Zoladex, given as a 100 mg S.C. depot, or the antioestrogen tamoxifen, given as three daily injections of 1 mg. Steroid treatment comprised a single dose of 10 microgram oestradiol benzoate or 2.0 mg progesterone, or a combination of the two hormones given 30 h apart. Ovariectomy had no significant effect on plasma oxytocin concentrations, although progesterone treatment produced an increase. The natriuresis in ovariectomised animals of 27% was smaller (P < 0.05) than that seen on the day of pro-oestrus and closer to that seen in the intact rat at oestrus. The responses in animals with suppressed oestrous cycles following treatment with tamoxifen were not significantly different from those observed following ovariectomy, neither was the diuresis following Zoladex. The renal responses were greater following treatment with oestradiol than in the ovariectomised group. Thus ovarian steroids do influence the renal responsiveness to oxytocin with oestradiol augmenting the response.

Animals↗

PubMed2000

Polymorphisms in CTLA-4 but not tumor necrosis factor-alpha or interleukin 1beta genes are associated with Wegener's granulomatosis.

OBJECTIVE: The genetic factors predisposing to Wegener's granulomatosis (WG) are largely unknown. T cells are clearly involved in the disease, as are the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin 1beta (IL-1beta). The cytotoxic T lymphocyte associated antigen-4 (CTLA-4) suppresses antigen-specific immune responses by opposing the CD28 pathway, and is crucial for a balanced T cell activation. Genetic variations in the TNF-alpha, IL-1beta, and CTLA-4 genes could thus be important in WG. METHODS: Polymorphisms in the genes coding for TNF-alpha, IL-1beta, and CTLA-4 were analyzed in 32 Swedish Caucasian patients and 109 ethnically matched controls. Results. A strong association of Ctla-4 (AT)n microsatellite to WG contrasts to the negative finding of associations between TNF-alpha NcoI, IL-1beta TaqI restriction fragment length polymorphism, and WG. The prevalence of the shortest Ctla-4 allele was decreased in patients with WG compared with healthy individuals (p < 0.0001, pc < 0.0016). CONCLUSIONS: This is the first report of a T cell related gene in association with WG. The Ctla-4 itself, or a gene close to Ctla-4, may thus contribute to the pathogenesis of WG by allowing an increased T cell activation by antigen.

Abatacept↗

PubMed2000

Upregulation of human cytotrophoblast invasion by hepatocyte growth factor.

Mesenchymal-epithelial interactions exert powerful influences on tissue architecture. At the molecular level, hepatocyte growth factor (HGF; produced by mesenchyme) and its c-met tyrosine kinase receptor (expressed on epithelial cells) participate in this paracrine dialogue. In the present study, anti-HGF immunoreactivity was usually detected in association with the mesenchymal cores of chorionic villi in situ, whereas cytotrophoblasts (CTBs) stained for c-met. In pre-eclampsia, mesenchymal HGF staining was either very low or was not observed, whereas CTB c-met expression was unchanged compared with control samples. These findings suggest that faulty signals emanating from the villus mesenchyme may contribute to the failure of CTB invasion that is associated with pre-eclampsia. In the present study, this hypothesis was tested and it was found that HGF treatment stimulates CTB invasion in vitro by four times. These immunolocalization and functional data indicate that HGF-c-met interactions play a key role in regulating the depth of CTB invasion in normal pregnancy and pre-eclampsia.

Case-Control Studies↗

PubMed2000

1376G-->T mutation of G6PD gene in Han and Li nationalities in Hainan, China.

OBJECTIVE: To investigate the 1376G-->T mutation of G6PD gene in the cases of G6PD deficiency in the Han nationality and the Li nationality of Hainan, China. METHODS: DNAs were extracted from the white blood cells of G6PD deficient cases by salt-out method. Allelic specific polymerase chain reaction was used to detect the 1376G-->T mutation. RESULTS: Fifty-nine Han nationality cases and 32 Li nationality cases were analysed; the 1376G-->T mutation was found in 19 Han cases(32.2%) and 18 Li cases(56.2%). CONCLUSION: 1376G-->T is a common mutation which causes G6PD deficiency in the Han nationality and the Li nationality in Hainan, China. Based on the phylogenetic tree of populations in China, these results indicate that the mutation might occur prior to the divergence of the Han and Li nationalities. It is of significance to study the mutations of G6PD gene in different nationalities in China for elucidating the origin, migration and evolution of the nationalities.

Biological Evolution↗

PubMed2000

An experimental study of effect of zheng tai instant powder on grand mal epilepsy.

Zheng Tai Instant Powder [symbol: see text] is a complex prescription of traditional Chinese medicine indicated for grand mal epilepsy. Its effect on central nervous system, energy metabolism, neurotransmitters and hemorheology were studied in animal models. The results demonstrated that the effect of Zheng Tai Instant Powder is mild, long-lasting and effective in treatment and prevention of epilepsy without any side effects.

Animals↗

PubMed2000

Reduced hypothalamic POMC and anterior pituitary CRF1 receptor mRNA levels after acute, but not chronic, daily "binge" intragastric alcohol administration.

BACKGROUND: Endogenous corticotropin-releasing factor (CRF), its pituitary CRF1 receptor, and proopiomelanocortin (POMC) may be involved in the hypothalamic-pituitary-adrenal (HPA) responses to alcohol. METHODS: Alcohol (1.5 g/kg) or water was administered intragastrically to male Fischer rats after the "binge" pattern regimen, that is, three times daily at 1 hr intervals at the beginning of the light cycle. The levels of CRF, CRF1 receptor, and POMC mRNAs in the hypothalamic-pituitary axis were measured after acute (1 day) or chronic (14 days) binge pattern alcohol administration. Plasma levels of ACTH and corticosterone were measured to examine time-dependent alterations of HPA responses. RESULTS: Plasma ACTH and corticosterone levels were elevated dramatically after 1 day of acute binge pattern alcohol administration. After 14 days of chronic alcohol, however, no elevation in plasma ACTH levels and an attenuated elevation in plasma corticosterone levels were found. CRF mRNA levels in the hypothalamus were not altered after either acute or chronic alcohol administration. CRF1 receptor mRNA levels in the anterior pituitary were decreased significantly after acute administration, with no change after chronic alcohol administration. POMC mRNA levels in the anterior pituitary were not altered by either acute or chronic alcohol administration. In the hypothalamus, POMC mRNA levels were decreased significantly after acute but not chronic binge alcohol administration. CONCLUSIONS: These results suggest that (1) rats exposed to chronic binge alcohol develop tolerance in HPA activity, as shown by no elevation of ACTH and an attenuated corticosterone response to chronic alcohol after initial dramatic elevations by acute alcohol administration; (2) a concurrent acute decrease in CRF1 receptor mRNA levels in the anterior pituitary is associated with increased HPA activity, and (3) alterations of POMC gene expression in the hypothalamic region may have implications for a molecular understanding of the neuroendocrine response to alcohol.

Administration, Oral↗

PubMed2000

[Application of intermittent-feeding of growth-limiting nutrients in suspension culture of insect cells(Sf21)].

On the basis of the growth and metabolism behavior inherent in suspended Sf21 insect cells, the intermittent feeding of growth-limiting nutrients(glucose and protein hydrolysates) was employed in the regulation of cellular growth during the cultivation by using the residual glucose concentration as a reference point. It was shown that as compared with the batch cultivation, the intermittent-feeding of growth-limiting nutrients effectively prolonged the growth and stationary phase for Sf21 insect cells grown in two representative culture medium(TC-100 and IPL-41). The maximum cell density was increased from 3.0 x 10(6) cells/ml to 6.5 x 10(6) cells/mL in TC-100 medium, and in IPL-41 medium, the maximum cell density was increased from 7.05 x 10(6) cells/mL to 9.0 x 10(6) cells/mL. As the defined nutrient solution was used for feeding in lieu of the complicated and expensive base medium, the technique would find prospects in large scale high-density cultivation of insect cells.

Animals↗

PubMed2000

Flow injection analysis of fluoride: optimization of experimental conditions and non-linear calibration using artificial neural networks.

This paper deals with the application of artificial neural networks (ANNs) to two common problems in spectroscopy: optimization of experimental conditions and non-linear calibration of the result, with particular reference to the determination of fluoride by flow injection analysis (FIA). The FIA system was based on the formation of a blue ternary complex between zirconium(IV), p-methyldibromoarsenazo and F- with the maximum absorption wavelength at 635 nm. First, optimization in terms of sensitivity and sampling rate was carried out by using jointly a central composite design and ANNs, and a neural network with a 3-7-1 structure was confirmed to be able to provide the maximum performance. Second, the relationship between the concentration of fluoride and its absorbance was modeled by ANNs. In this process, cross-validation and leave-k-out were used. The results showed that good prediction was attained in the 1-4-1 neural net. The trained networks proved to be very powerful in both applications. The proposed method was successfully applied to the determination of free fluoride in tea and toothpaste with recoveries between 96 and 101%.

Calibration↗

PubMed2000

[Monitoring dopamine release by fast cyclic voltammetry: an in vivo study].

AIM AND METHODS: Using fast cyclic voltammetry (FCV) and carbon fibre microelectrode (CFMe), we monitored dopamine (DA) release from caudate putamen(CPu), nucleus accumbens(Acb) and central amygdaloid nucleus(CAN) of normal rats in vivo, in order to find out the suitable parameters to evoke DA release of certain area. DA release was evoked by electrical stimulation of medial forebrain bundle(MFB) or ventral tegmental area(VTA). RESULTS: DA release from CPu, Acb or CAN were different in contents and the characteristics of dynamics. CONCLUSION: Different parameters should be used according to the different sites of stimulation in order to get the maximal DA release during the experiment.

Animals↗