Biomedical subjects

Liping Zhao

Publications and source records attributed to Liping Zhao.

27 records · Page 2Linked to original sources

PubMed2003

[Biodiversity of bacterial isolates on three different media from coking wastewater treatment system].

Bacteria from coking wastewater treatment sludge samples were directly plated on three different isolation media (YPG, LB and WW) and the biodiversity of isolates was examined with DNA fingerprinting. Plate counts with YPG, LB and WW media were 1.6 x 10(6) CFU/mL, 7.0 x 10(5) CFU/mL and 9.8 x 10(5) CFU/mL respectively. 137 single colony isolates were obtained from these three media. ARDRA with enzymes Hinfl revealed 14 operational taxonomic units (OUT) which were dominated by YPG-OTU1 group accounting for 34 isolates and WW-OTU6 group for 25 isolates. The biodiversity of isolates from these two dominant OUT groups was further investigated by a genomic fingerprinting technique, ERIC-PCR. The results indicated that there were 20 different ERIC-PCR types present among the YPG-OTU1 group and only 3 among the WW-OTU6 group. The data showed that the populations of bacteria isolated on three different media were significantly different from each other and a higher degree of genetic diversity was observed among strains isolated from YPG media. So YPG may be recommended to be used for a non-selective medium for isolating more diversified bacteria from wastewater bio-treatment systems.

Bacteria↗

PubMed2002

Leptin regulates bone formation via the sympathetic nervous system.

We previously showed that leptin inhibits bone formation by an undefined mechanism. Here, we show that hypothalamic leptin-dependent antiosteogenic and anorexigenic networks differ, and that the peripheral mediators of leptin antiosteogenic function appear to be neuronal. Neuropeptides mediating leptin anorexigenic function do not affect bone formation. Leptin deficiency results in low sympathetic tone, and genetic or pharmacological ablation of adrenergic signaling leads to a leptin-resistant high bone mass. beta-adrenergic receptors on osteoblasts regulate their proliferation, and a beta-adrenergic agonist decreases bone mass in leptin-deficient and wild-type mice while a beta-adrenergic antagonist increases bone mass in wild-type and ovariectomized mice. None of these manipulations affects body weight. This study demonstrates a leptin-dependent neuronal regulation of bone formation with potential therapeutic implications for osteoporosis.

Adrenergic beta-Antagonists↗

PubMed2002

Development of a transgenic green fluorescent protein lineage marker for steroidogenic factor 1.

Knockout (KO) mice lacking steroidogenic factor 1 (SF-1, officially designated Nr5a1) have a complex phenotype that includes adrenal and gonadal agenesis, impaired function of pituitary gonadotropes, and abnormalities of the ventromedial hypothalamic nucleus (VMH). To develop a lineage marker for cells that express SF-1, we used bacterial artificial chromosome (BAC) transgenesis. A BAC fragment containing 50 kb of the mouse Nr5a1 gene was placed upstream of the coding sequence for enhanced green fluorescent protein (eGFP) and used to generate SF-1/eGFP transgenic mice. These sequences directed eGFP expression to multiple cell lineages that express SF-1, including steroidogenic cells of the adrenal cortex, testes, and ovaries, VMH neurons, and reticuloendothelial cells of the spleen. Despite the essential role of SF-1 in gonadotropes, eGFP was not expressed in the anterior pituitary. These studies show that 50 kb of the mouse Nr5a1 gene can target transgenic expression to multiple cell lineages that normally express SF-1. The SF-1/eGFP transgene provides a valuable tool to expand our understanding of the actions of SF-1 in endocrine development and function.

Adrenal Cortex↗

PubMed2002

The roles of circulating high-density lipoproteins and trophic hormones in the phenotype of knockout mice lacking the steroidogenic acute regulatory protein.

The steroidogenic acute regulatory protein (StAR) is essential for the regulated production of steroid hormones, mediating the translocation of intracellular cholesterol to the inner mitochondrial membrane where steroidogenesis begins. Steroidogenic cells lacking StAR have impaired steroidogenesis and progressively accumulate lipid, ultimately causing cytopathic changes and deterioration of steroidogenic capacity. Developmental studies of StAR knockout (KO) mice have correlated gonadal lipid deposits with puberty, suggesting that trophic hormones contribute to this lipid accumulation. To delineate the role of gonadotropins in this process, we examined double mutant mice deficient in both StAR and gonadotropins [StAR KO/hpg (hypogonadal)]. Lipid accumulation was ameliorated considerably in StAR KO/hpg mice but was restored by treatment with exogenous gonadotropins, directly linking trophic hormones with gonadal lipid accumulation. To define the relative roles of exogenous vs. endogenous cholesterol in the lipid accumulation, we also examined mice lacking both StAR and apolipoprotein A-I (StAR KO/Apo A-I KO). Steroidogenic tissues of StAR KO/Apo A-I KO mice had markedly decreased lipid deposits, supporting the predominant role of high-density lipoprotein-derived cholesterol in the lipid accumulation caused by StAR deficiency. Finally, we used electron microscopy to compare mitochondrial ultrastructure in StAR KO and cholesterol side-chain cleavage enzyme (Cyp11a1) KO mice; despite comparable lipid accumulation within adrenocortical cells, the effects of StAR deficiency and Cyp11a1 deficiency on mitochondrial ultrastructure were markedly different. These findings extend our understanding of steroidogenic cell dysfunction in StAR KO mice and highlight key roles of trophic hormones and high-density lipoprotein-derived cholesterol in lipid deposits within StAR-deficient steroidogenic cells.

Adrenal Cortex↗

PubMed2002

Development of a transgenic green fluorescent protein lineage marker for steroidogenic factor 1.

Knockout mice lacking steroidogenic factor 1 (SF-1, officially designated Nr5a1) have a complex phenotype that includes adrenal and gonadal agenesis, impaired expression of pituitary gonadotropins, and structural abnormalities of the ventromedial hypothalamic nucleus. To explore further how SF-1 regulates endocrine function, we used bacterial artificial chromosome transgenesis to develop a lineage marker for SF-1-expressing cells. A genomic fragment containing 50 kb of the mouse Nr5a1 gene was used to target enhanced green fluorescent protein (eGFP) in transgenic mice. These sequences directed eGFP to multiple cell lineages that express SF-1, including steroidogenic cells of the adrenal cortex, testes, and ovaries, neurons of the ventromedial hypothalamic nucleus, and reticuloendothelial cells of the spleen. Despite the proven role of SF-1 in gonadotrope function, eGFP was not expressed in the anterior pituitary. These experiments show that 50 kb of the mouse Nr5a1 gene can target transgenic expression to multiple cell lineages that normally express SF-1. The SF-1/eGFP transgenic mice will facilitate approaches such as fluorescence-activated cell sorting of eGFP-positive cells and DNA microarray analyses to expand our understanding of the multiple actions of SF-1 in endocrine development and function.

Adrenal Glands↗

PubMed2002

Steroidogenic factor 1: an essential mediator of endocrine development.

The orphan nuclear receptor steroidogenic factor 1 (SF-1, also called Ad4BP and officially designated NR5A1) has emerged as an essential regulator of endocrine development and function. Initially identified as a tissue-specific transcriptional regulator of the cytochrome P450 steroid hydroxylases, SF-1 has considerably broader roles, as evidenced from studies in knockout mice lacking SF-1. The SF-1-knockout mice lacked adrenal glands and gonads and therefore died from adrenal insufficiency within the first week after birth. In addition, SF-1 knockout mice exhibited male-to-female sex reversal of their internal and external genitalia, impaired expression of multiple markers of pituitary gonadotropes, and agenesis of the ventromedial hypothalamic nucleus (VMH). These studies delineated essential roles of SF-I in regulating endocrine differentiation and function at multiple levels, particularly with respect to reproduction. This chapter will review the experiments that established SF-1 as a pivotal, global determinant of endocrine differentiation and function. We next discuss recent insights into the mechanisms controlling the expression and function of SF-1 as well as the current status of research aimed at delineating its roles in specific tissues. Finally, we highlight areas where additional studies are needed to expand our understanding of SF-1 action.

Animals↗

PubMed2002

[Drug resistance of Mycobacterium tuberculosis in a nationwide epidemiological survey in China in the year of 2000].

OBJECTIVE: To determine the state of anti-tuberculosis drug resistance, and to analyze the trend of drug resistance rate and assess its impact on National TB Programme (NTP). METHODS: 392 Mycobacterium tuberculosis (MTB) isolates from a nationwide epidemiological survey were subjected to susceptibility testing against 6 anti-tuberculosis drugs using the absolute concentration method. RESULTS: The resistant rate to any drug was 27.8% in all MTB isolates, 18.6% in 263 new cases and 46.5% in 129 previously treated cases. Multi-drug resistant rate (MDR) was 10.7%. Initial and acquired MDR was 7.6% and 17.1%. Any resistance to INH, SM, RFP, PAS-Na, EMB and TB(1) was 17.6%, 17.3%, 16.6%, 2.8%, 1.5% and 1.3%, respectively. The resistant rates to 1, 2, 3 and 4 or more drugs were 7.6%, 4.6%, 4.6% and 1.9% in new cases and 14.7%, 19.4%, 10.1% and 2.3% in previously treated cases. The initial drug resistant rate did not show significant difference (P > 0.05) among different sex and age groups. CONCLUSIONS: Compared to the previous data, the total drug resistance and initial drug resistance decreased significantly, but were still high. More attention should be paid to the trend of resistance of MTB to first-line drugs and especially the high incidence of MDR-TB.

Age Factors↗

PubMed2002

[Type III secretion system in Se9R can recognize and secret harpin in Erwinia amylovora].

Bacterial pathogens of both animals and plants use type III secretion machines to secret virulence proteins. The signal that leads to tye type III secretion is encoded as stem loop structure in the messenger RNA. Harpin, produced by Erwinia anylovora is secreted via type III secretion. Erwinia carotovora Se9R and Erwinia amylovora belong to the same genus and they use type III secretion machines to secret virulence proteins. We used PCR to amplify hrpN from pCPP430 which harbors hrpN gene cluster, and cloned it to pGEM-T vector to get pWGF1, which was then chemically transformed into DH5 alpha (pCPP430hrpN-) and electrotransformed into Se9R. DH5 alpha (pCPP430hrpN-/pWGF1) induced hypersensitive response on tomato leaf and Se9R(pWGF1) showed significantly reduced virulence than Se9R on Chinese cabbage leaf. Western-blotting analysis of the CFEP of Se9R(pWGF1) showed production of harpin protein. These results suggest the type III secretion machine in Se9R can recognize secretion singal in the gene of harpin in Erwinia amylovora and secret it as a biologically native form.

Bacterial Outer Membrane Proteins↗

PubMedDate not supplied

Metabonomic study on the biochemical profiles of a hydrocortisone-induced animal model.

This work describes the metabonomic study of a biochemical modification in vivo induced by high dose of hydrocortisone, which led to a unique pathologic condition similar to the 'kidney deficiency syndromes', an early stage of obesity and diabetes in traditional Chinese medicine. The methodology of the metabonomic approach consisted of GC/MS and multivariate statistical technique for the establishment of urine metabolic patterns of the treatment rats. In the study, 24-h urine was collected pre-dose and at days 1, 3, 7, and 10 post-dose after rats were injected with hydrocortisone at 1.5 mg/100 g. The acquired data were transferred into Matlab to be processed using principal components analysis (PCA). The results indicated that clear and consistent biochemical changes following hydrocortisone intervention under controlled conditions could be identified using chemometric analysis. The work suggests that this metabonomic approach could be used as a potentially powerful tool to investigate the biochemical changes of certain physiopathologic conditions such as metabolic syndrome, as an early diagnostic means.

Animals↗