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Biomedical subjects

H Shi

Publications and source records attributed to H Shi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Neurochemical phenotype of sympathetic nervous system outflow from brain to white fat.

The sympathetic innervation of white adipose tissue (WAT) appears to be a dominant mechanism triggering lipolysis. The purpose of this study was to determine the neurochemical phenotype of neurons comprising the sympathetic outflow from brain to WAT. This was accomplished by injecting Siberian hamster WAT with a viral retrograde transneuronal tract tracer, the pseudorabies virus (PRV), in combination with immunocytochemical characterization of several neurotransmitters or their synthetic enzymes in the brain. Catecholaminergic (tyrosine hydroxylase [TH] and dopamine-beta-hydroxylase [DBH] immunoreactivity) and peptidergic (arginine vasopressin [AVP] and oxytocin [OXY] immunoreactivity) neurons were part of this outflow, but the percentage of double-labeled cells was small, consistent with previous studies. Brainstem PRV + TH- or PRV + DBH-labeled cells were in previously identified noradrenergic areas (A5, A6, and subcoeruleus, rostroventrolateral medulla [RVL], some reticular nuclei). Forebrain double labeling was greatest in the paraventricular (TH, AVP, OXY) and suprachiasmatic (AVP) nuclei, both implicated in the central control of lipolysis. Differences between the PRV double labeling reported here for WAT versus that of other sympathetic peripheral targets were PRV + DBH in A5 and RVL, and PRV + TH in RVL and in the lateral paragigantocellular and lateral reticular nuclei. Collectively, these results begin to identify the neurochemical identity of the sympathetic outflow from brain to WAT.

Adipose Tissue↗
PubMed2001

Display of green fluorescent protein on Escherichia coli cell surface.

In this study, expression of green fluorescence protein (GFP) on the external surface of Escherichia coli was achieved by construction of a fusion protein between Lpp-OmpA hybrid and a GFP variant, GFPmut2. The GFP was fused in frame to the carboxyl-terminus of Lpp-OmpA fusion previously shown to direct various other heterologous proteins to E. coli cell surface. Western blot analysis of membrane fractions identified the Lpp-OmpA-GFP fusion protein with the expected size (43 kDa). Immunofluorescence microscopy, immunoelectron microscopy, protease and extracellular pH sensitivity assays further confirmed that GFP is anchored on the outer membrane. The GFP displayed on the E. coli outer surface retained its fluorescence and was not susceptible to the indigenous outer membrane protease OmpT even though there are two putative OmpT proteolytic sites present in GFP. Optimization of the expression conditions was conducted using fluorometry, eliminating cumbersome immuno-labeling procedures. Surface-displayed GFP could be used in a variety of applications including screening of polypeptide libraries, development of live vaccines, construction of whole cell allosteric biosensors, and signal transduction studies.

Journal Article↗
PubMed2001

Cloning, expression, purification, and characterization of rat MMP-12.

Macrophage metalloelastase (MMP-12) is implicated in the pathology of many diseases such as emphysema, aortic lesions and cancer. Recently, MMP-12 was cloned and purified from mouse and human macrophages. We report here the expression of the full-length and catalytic domain of rat MMP-12 in Escherichia coli and characterization of the purified enzyme. Inclusion bodies of expressed rat MMP-12 catalytic domain were denatured and refolded using a new method, and then affinity purified to near homogeneity with zinc-chelating Sepharose. The purified rat MMP-12 catalytic domain was highly active in digesting substrates, having a K(m) of 12 microM and optimal pH of 7.5--8.5. During investigation of natural substrate specificity, we found that rat MMP-12 catalytic domain was able to completely degrade collagen-V, partially degrade collagen-I, but it was unable to digest collagen-IV. The enzyme could also degrade osteonectin, vitronectin, and fibronectin, but not laminin and albumin. The catalytic properties and natural substrate specificity of rat MMP-12 catalytic domain differed from those of human MMP-12 catalytic domain.

Animals↗
PubMed2001

Expression and localization of luteinizing hormone receptor in the female mouse reproductive tract.

The presence of the LH receptor (LHR) in nongonadal tissues of the reproductive tract has been reported, but localization studies have not been performed. Our objectives were to demonstrate the presence of LHR in the reproductive tract and to localize receptor expression. Reproductive age rats and mice were obtained and (125)I-hCG binding assays were performed on membrane preparations from the uterus, ovary, liver, and testis. In situ hybridizations were performed using (35)S-labeled antisense and sense RNA probes prepared from nucleotides 1-591 of the mouse LHR cDNA. Specific hCG binding was detected in membrane preparations from the ovary, uterus, and testis but not in the liver in both the rat and mouse. In the ovary, LHR mRNA was localized in theca cells, large follicles, and corpora lutea as expected. In the uterus, LHR mRNA was expressed in stromal cells of the endometrium and in the uterine serosa. Uterine smooth muscle cells had low levels of expression, and the endometrial epithelium was negative. In the oviduct, high levels of LHR expression were noted on the serosa and in subepithelial cells. Oviductal smooth muscle had low expression, and the epithelium was negative. We conclude that functional, nongonadal LHR are expressed in the mouse reproductive tract. The presence and localization of LHR expression in the mouse reproductive tract lay the foundation for transgenic models to address the physiologic role of these receptors.

Animals↗
PubMed2001

Expression of multiple subtypes of muscarinic receptors and cellular distribution in the human heart.

Five isoforms of the muscarinic acetylcholine receptor (mAChR) have been identified by molecular cloning and designated m(1)-m(5), of which four correspond to the functional subtypes M(1), M(2), M(3), and M(4) in primary tissues. The presence of M(5) receptors in tissues remains uncertain. The present study was designed to explore the diversity and cellular distribution of various mAChR subtypes in human hearts. Competition binding of [N-methyl-(3)H]-scopolamine methyl chloride with various mAChR antagonists yielded data consistent with the presence of multiple subtypes (M(1)/M(2)/M(3)/M(5)) of mAChRs in both human atrial (HA) and ventricular (HV) tissues. Expression of mRNAs encoding all five subtypes was readily detected by reverse transcription-polymerase chain reaction in both HA and HV samples. Immunoblotting with subtype-specific antibodies confirmed the presence of M(1), M(2), M(3), and M(5), but not M(4), proteins in membrane preparations from both HA and HV. The protein levels of M(1) and M(2) were comparable between HA and HV. Although the density of M(3) appeared approximately 10-fold higher in HV than HA, that of M(5) was approximately 5 times lower in HV than in HA. Positive immunostaining of single ventricular myocytes by M(1), M(2), M(3), and M(5) antibodies, respectively, was consistently detected. Under confocal microscopy, M(5) showed characteristic localization to the intercalated discs, whereas other subtypes were more evenly distributed throughout the surface membrane. Our results provide the first molecular evidence for the presence of multiple subtypes of mAChR, including endogenous M(5) receptors, in human hearts and suggest that different subtypes have different tissue distributions and cellular localization.

Binding, Competitive↗
PubMed2001

Membrane topology and immunolocalization of CHIF in kidney and intestine.

Corticosteroid hormone-induced factor (CHIF) is an aldosterone-induced gene, the function of which is yet unknown. It is specifically expressed in kidney collecting duct (CD) and distal colon and is upregulated by either Na+ deprivation or K+ loading. Hence, it may play a role in epithelial electrolyte transport. Previous studies have characterized regulation and tissue distribution of CHIF mRNA but provided no information on the protein itself. The present paper addresses this issue by using Western blotting, immunochemistry, and in vitro translation. CHIF is an approximately 8-kDa membranal protein, and protease digestion experiments suggest that its COOH tail faces the cell interior. The protein is abundant in distal colon, kidney medulla, and papilla but cannot be detected in a variety of other tissues. Confocal immunocytochemistry demonstrates that CHIF is present in the basolateral membrane of CD principal cells and distal colon surface cells, with occasional intracellular staining. Dexamethasone and low Na+ intake increase the abundance of CHIF. Unlike previous Northern data, induction of CHIF protein by low-Na+ intake was apparent not only in the distal colon but also in the kidney.

Animals↗
PubMed2001

In vitro phosphorylation of COOH termini of the epithelial Na(+) channel and its effects on channel activity in Xenopus oocytes.

Recent findings have suggested the involvement of protein phosphorylation in the regulation of the epithelial Na(+) channel (ENaC). This study reports the in vitro phosphorylation of the COOH termini of ENaC subunits expressed as glutathione S-transferase fusion proteins. Channel subunits were specifically phosphorylated by kinase-enriched cytosolic fractions derived from rat colon. The phosphorylation observed was not mediated by the serum- and glucocorticoid-regulated kinase sgk. For the gamma-subunit, phosphorylation occurred on a single, well-conserved threonine residue located in the immediate vicinity of the PY motif (T630). The analogous residue on beta(S620) was phosphorylated as well. The possible role of gammaT630 and betaS620 in channel function was studied in Xenopus laevis oocytes. Mutating these residues to alanine had no effect on the basal channel-mediated current. They do, however, inhibit the sgk-induced increase in channel activity but only in oocytes that were preincubated in low Na(+) and had a high basal Na(+) current. Thus mutating gammaT630 or betaS620 may limit the maximal channel activity achieved by a combination of sgk and low Na(+).

Animals↗
PubMed2001

Temperature-induced expression of phb genes in Escherichia coli and the effect of temperature patterns on the production of poly-3-hydroxybutyrate.

The plasmid pNDTM2 was constructed to contain the p(R)-p(L) promoter and the phbC, A, and B genes which code for PHB synthase, beta-ketothiolase, and acetoacetyl-CoA reductase, respectively. This plasmid was transformed into Escherichia coli XL1-Blue. The effect of several thermal induction patterns on the production of poly-3-hydroxybutyric acid (PHB) was investigated based on fermentor experiments. Based on the experimental results with different induction patterns, it was found that the temperature should be controlled at 34 degrees C during the initial 10 h of cultivation to promote cell growth, and then it should be increased to 40 degrees C for induction. Then the temperature should be lowered to 37 degrees C after 5 h to relieve the effect of the heat shock.

Journal Article↗
PubMed2001

[Gene mapping on Blepharophimosis Epicanthus Inversus and Ptosis syndrome type I in Chinese family].

OBJECTIVE: To map the gene responsible for Blepharophimosis Epicanthus Inversus and Ptosis syndrome(BPES) type I in a Chinese family. METHODS: Polymorphisms of 4 satellite markers of 3q were analyzed and linkage analysis was performed using linkage software (MLINK, Version 5.2). RESULTS: No deletion was detected for the four markers. The maximum lod scores were: 0.77 (theta = 0.00) at D3S3045; 3.61 (theta = 0.00) at D3S1764; 0.11 (theta = 0.3) at D3S3053 and -0.03 (theta = 0.4) at D3S2436. CONCLUSION: The gene responsible for BPES in the Chinese family was tightly linked to D3S1764.

Abnormalities, Multiple↗
PubMed2001

[Hydrodynamic property of internal airlift loop bioreactor with cells immobilized onto ceramic honeycomb support(IALBR-CICHS)].

An internal airlift loop biorector with cells immobilized onto ceramic honeycomb support(IALBR-CICHS) was developed based on the bubble columns(BC) and airlift(AL) bioreactor by installing a ceramic honeycomb support in the draught tube. Their hydrodynamics were respectively studied by the tracer element to determine their retention time distribution (RTD). Experiment and theory analysis indicated that the IALBR-CICHS had more efficacious reactive volume rate(eta) and less short-circuit rate(lambda) for fluid flow compared with the BC and AL bioreactor.

Bioreactors↗
PubMed2001

[Quinoline removal in fluidized-bed bioreactor using immobilized cells].

Burkholderia pickettii, capable of using quinoline as sole source of carbon, nitrogen and energy, was immobilized by an innovative PVA-H3BO3-gauze method. A fluidized-bed bioreactor, in which immobilized cells were added, was constructed to degrade quinoline in wastewater. When the initial concentrations of quinoline were 100, 350 and 500 mg/L, the bioreactor can remove it completely within 2.5, 6 and 12 hours respectively. A series of zero-order reaction equations were proposed to describe quinoline biodegradation process in this bioreactor kinetically. In continuous flow experiments, the performance of the bioreactor was investigated at different HRT (dilution rate) for different quinoline concentrations in wastewater and the tolerance against shock loading was determined by increasing quinoline concentration from 100 to 300 to 500 mg/L at HRT 4 hours.

Bioreactors↗
PubMed2001

[Genotype polymorphism and its implications of mannose-binding protein allele in 5 Chinese nationalities].

OBJECTIVE: To detect the genotypes and sequences of the exon 1 of human mannose-binding protein (MBP) allele in 5 Chinese nationalities. METHODS: The genotypes of MBP gene of 5 Chinese nationalities were detected by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP). The exon 1 of the MBP gene of 22 Chinese Hans was analyzed by using ABI 310 genetic analyzer. RESULTS: The DNA sequences of exon 1 of Chinese MBP gene were acquired. The allele frequencies of the codon 54 of the MBP gene (MBP-54) of 5 Chinese nationalities were 0.181(Hans), 0.128(Uygurs), 0.181(Mongols), 0.179(Tibetans) and 0.181(Yis). The allele distribution for MBP-54 mutation of 5 Chinese nationalities was in good agreement with Hardy-Weinberg equilibrium. Compared with the Hans, Uygurs had a lower MBP-54 mutation rate. There were no differences in the allele frequencies between the chronic hepatitis B patients and health controls in Chinese Hans. The mutations of the codons 52 and 57 were not detected in this study. CONCLUSION: A higher prevalence of MBP-54 mutation was found in 5 Chinese nationalities, MBP-54 mutation was not associated with the persistence of hepatitis B.

Adolescent↗
PubMed2001

[Kinetic study on photocatalytic degradation of p-chlorobenzoate at different light intensities].

Kinetics of photocatalytic degradation were investigated at different light intensities using para-chlorobenzoate as a model pollutant. It was experimentally found that the Langmuir-Hinshelwood model could satisfactorily describe all the kinetic processes. However, the two crucial parameters involved in the L-H model were dependent of the incident light intensity. With elevated light intensity, the rate constant, kr, increased whereas the apparent adsorption constant, Ks, decreased. Grossly, both kr and Ks-1 were correlated with the light intensity in a power law. The experimental discovery implies that the photonic efficiency would be much deteriorated with increased radiation intensity although the reaction rate can be enhanced. Applying mild light intensity might be one of the critical strategies in photocatalytic reactor design to improve the photonic efficiency.

Catalysis↗
PubMed2001

[Comparison of 2D-CT and 3D-CT in diagnosing mid-facial fractures].

OBJECTIVE: The aim of this study is to measure the value of 2D-CT and 3D-CT in diagnosing mid-facial fractures. METHODS: 50 patients who suffered from facial trauma were scanned with both conventional axial-CT (3 mm thickness) and 3D reconstruction (surface shaded display, SSD). The scanning region was ranged from the upper teeth to superior edge of the orbit. Coronal-CT imaging was performed in 21 patients in order to compare with that of axial and 3D CT images. RESULTS: Axial 2D-CT can be better to identify facial fractures than 3D reconstruction in such sites that are medial wall of the maxilla (5/0 sides), lateroposterior wall of the maxilla (49/44 sides), upper alveoli (14/12 sides), lateral wall of the orbit (34/31 sides), and pterygoid process of the sphenoid bone (19/9 sides). Three-dimensional reconstruction was superior to 2D-CT in demonstrating fracture of anterior wall of the maxilla (60/57 sides) and shapes of the facial fracture. 2D-CT is similar to 3D-CT in diagnosing fractures of nasal bone (20 sides), zygomatic bone and arch (24 sides). Owing to the partial volume effect, the medial wall of normal or abnormal orbit could not be correctly evaluated on 3D reformation images. CONCLUSION: It is concluded that 2D-CT should be regarded as the foundations of diagnosing facial fractures, and 3D-reconstruction as a useful complementary tool.

Adolescent↗
PubMed2001

RNA interference in Trypanosoma brucei: cloning of small interfering RNAs provides evidence for retroposon-derived 24-26-nucleotide RNAs.

In animals and protozoa, gene-specific double-stranded RNA (dsRNA) triggers degradation of homologous cellular RNAs, a phenomenon known as RNA interference (RNAi). In vitro and in vivo dsRNA is processed by a nuclease to produce 21-25-nt small interfering RNAs (siRNAs) that guide target RNA degradation. Here we show that activation of RNAi in Trypanosoma bruceiby expression or electroporation of actin dsRNA results in production of actin siRNAs and that 10% of these RNAs sediment as high-molecular-weight complexes at 100,000 x g. To characterize actin siRNAs, we established a cloning and enrichment strategy starting from 20-30 nt RNAs isolated from high-speed pellet and supernatant fractions. Sequence analysis revealed that actin siRNAs are 24-26 nt long and their distribution relative to actin dsRNA was similar in the two fractions. By sequencing over 1,300 fragments derived from the high-speed pellet fraction RNA, we found abundant 24-26-nt-long fragments homologous to the ubiquitous retroposon INGI and the site-specific retroposon SLACS. Northern hybridization with strand-specific probes confirmed that retroposon-derived 24-26-nt RNAs are present in both supernatant and high-speed pellet fractions and that they are constitutively expressed. We speculate that RNAi in trypanosomes serves a housekeeping function and is likely to be involved in silencing retroposon transcripts.

Actins↗
PubMed2001

Genotypes and polymorphisms of mutant CCR5-delta 32, CCR2-64I and SDF1-3' a HIV-1 resistance alleles in indigenous Han Chinese.

OBJECTIVE: To evaluate the frequencies and polymorphisms of CCR5-delta 32, CCR2-64I and SDF1-3' A alleles conferring resistance to HIV-1 infection in Chinese population from Han ethnic origin. METHODS: This cohort was comprised of 1251 subjects (915 men and 336 women) aged 15-80 years and none was HIV-1 positive. Genotyping of allelic CCR5-delta 32, CCR2-64I and SDF1-3' A variants was performed using PCR or PCR/RFLP assay, and further confirmed by direct DNA sequencing. RESULTS: Our finding shows that the delta 32 deletion mutation in the CCR5 gene does occur in this population and can be inherited in a Mendelian fashion in indigenous Han Chinese at a very low frequency of 0.00119 (n = 1254). The frequencies of mutant CCR2-64I and SDF1-3' A alleles were 0.20023 (n = 1251) and 0.2873 (n = 893), in this population, which are higher than those found in American Caucasians. Furthermore the polymorphisms of CCR2-64I and SDF1-3' A alleles in the Han Chinese population were different from those in American Caucasians. Statistical analysis showed that the genotype distribution of CCR5-delta 32, CCR2-64I and SDF1-3' A alleles was in equilibrium according to the Hardy-Weinberg equation. CONCLUSION: The CCR5-delta 32 mutation may not be a major resistant factor against HIV-1 infection in indigenous Han Chinese. The significance of higher frequencies of CCR2-641 and SDF1-3' A alleles (0.20023 and 0.2791) in the Han population remains to be clarified in HIV-1-positive carriers and AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Prevalence of CMV in arterial walls and leukocytes in patients with atherosclerosis.

OBJECTIVE: To investigate the association of cylomegalovirus with atherosclerosis. METHODS: The presence of cylomegalovirus (CMV) nucleic acids was demonstrated in carotid and coronary arteries of patients with and without atherosclerosis by polymerase chain reaction (PCR). CMV was detected by PCR in the blood of patients with and without atherosclerosis. RESULTS: 83.3%-86.7% of the samples obtained from atherosclerotic patient arterial walls were shown to contain viral nucleic acids (CMV), CMV could be found among 6.7% of patients' arterial wall without atherosclerosis, significant difference can be found between them (P < 0.01). In blood CMV could be found in 42.4% of patients with atherosclerosis, in the control group, only 3% of samples had CMV, P < 0.01. CONCLUSION: CMV plays an important role in the pathologic process of the atherosclerosis and the atherosclerotic cerebral infarction.

Aged↗