Biomedical subjects

G Tang

Publications and source records attributed to G Tang.

At least 55 records · Page 3Linked to original sources

PubMed2000

Characterization of the two saccharopine dehydrogenase isozymes of lysine catabolism encoded by the single composite AtLKR/SDH locus of Arabidopsis.

Arabidopsis plants possess a composite AtLKR/SDH locus encoding two different polypeptides involved in lysine catabolism: a bifunctional lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) enzyme and a monofunctional SDH enzyme. To unravel the physiological significance of these two enzymes, we analyzed their subcellular localization and detailed biochemical properties. Sucrose gradient analysis showed that the two enzymes are localized in the cytosol and therefore may operate at relatively neutral pH values in vivo. Yet while the physiological pH may provide an optimum environment for LKR activity, the pH optima for the activities of both the linked and non-linked SDH enzymes were above pH 9, suggesting that these two enzymes may operate under suboptimal conditions in vivo. The basic biochemical properties of the monofunctional SDH, including its pH optimum as well as the apparent Michaelis constant (K(m)) values for its substrates saccharopine and nicotinamide adenine dinucleotide at neutral and basic pH values, were similar to those of its SDH counterpart that is linked to LKR. Taken together, our results suggest that production of the monofunctional SDH provides Arabidopsis plants with enhanced levels of SDH activity (maximum initial velocity), rather than with an SDH isozyme with significantly altered kinetic parameters. Excess levels of this enzyme might enable efficient flux of lysine catabolism via the SDH reaction in the unfavorable physiological pH of the cytosol.

Arabidopsis↗

PubMed2000

Crystallization and preliminary X-ray crystallographic analysis of water channel AQP1.

Aquaporin-1 (AQP1), a water channel from bovine red blood cells has been deglycosylated, purified to homogeneity and crystallized in a form suitable for X-ray crystallographic study. Crystals are grown using polyethylene glycol as precipitant and belong to the tetragonal space group I422, with unit-cell parameters a = b = 93.4, c = 180.4 A. The crystals diffract beyond 2.2 A resolution.

Animals↗

PubMed2000

Perimortem Caesarean section: two case reports and a management protocol.

Perimortem Caesarean section is a rare clinical event. Two cases are reported. Both cases had poor outcomes. The impact of this was traumatic for the trainee specialists who managed the two cases. The relevant literature has been reviewed and a protocol for the management of this rare emergency is presented.

Adult↗

PubMed2000

Altered L-type Ca(2+) channel currents in vascular smooth muscle cells from experimental diabetic rats.

Vascular complications of diabetes are associated with abnormal Ca(2+) handling by vascular smooth muscle cells (SMCs) in which the alteration in L-type voltage-dependent Ca(2+) channel (VDCC) currents may play an important role. In the present study, the characteristics of L-type VDCC currents in tail artery SMCs from streptozotocin-induced diabetic rats were examined. The densities, but not the voltage dependence, of L-type VDCC currents were reduced as diabetes progressed from 1 wk to 3 mo. The inhibitory effect of dibutyryl-cAMP on L-type VDCC currents was greater in diabetic SMCs than in age-matched control cells (P < 0.01). Both the stimulatory effect of BAY K 8644 and the inhibitory effect of nifedipine on L-type VDCC currents were significantly enhanced in diabetic cells. The diabetes-related abnormalities in L-type VDCC currents were mimicked by culturing SMCs with a high concentration of glucose. Our results suggest that the properties of L-type VDCC in diabetic vascular SMCs were significantly altered, partially related to the increased L-type VDCC sensitivity to cAMP and hyperglycemia.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed2000

[Evaluation for biocompatibility of poly-(3-hydroxypropyl)-DL-aspartamide].

To evaluate the biocompatibility of poly-(3-hydroxypropyl)-DL-aspartamide(PHPA), we utilized the laboratory methods, including subcutaneous implantation, histological examination, blood biochemical and micronucleus test. Histological examination revealed a nonspecific foreign body reaction around the PHPA and a slight inflammation around the small blood vessels of the liver on the 13th day, but all these reactions diminished or disappeared gradually after 34 days of implantation. The structures and functions of liver and kidney were normal. The results indicate that PHPA possesses a good nature in biocompatibility.

Alanine Transaminase↗

PubMed2000

Location of the vertebral artery in the cervicothoracic junction.

Eight sectioned specimens and 8 cadavers were used to evaluate the location of the vertebral artery in the cervicothoracic junction. The results of the measurements showed that there was no significant difference between either sides at the C7-T1 junction in terms of all distances taken. The mean width of the vertebral artery was 2.9 mm at the levels of the C-7 and T-1. The sagittal distance between the vertebral artery and the posterior cortex was 16.8+/-3.0 mm at the C7 and 21.7+/-2.8 mm at T-1. The coronal distance between the vertebral artery and the midline of the vertebra was 17.5+/-1.8 mm at the C7 and 22.3+/-2.9 mm at the T-1. The mean angle between the line connecting the lateral border of the vertebral artery with the posterior midway of the lateral mass and the parasagittal line at C-7 was 14.1+/-6.1 degrees. The mean angle of the vertebral artery with respect to the midline was 22.8+/-6.4 degrees. This study suggests that the vertebral artery has closer anatomic relationship to the C-7 lateral mass. Care should be taken to avoid injury to the vertebral artery if lateral mass screw fixation at the C-7 is intended.

Bone Screws↗

PubMed2000

[Experimental study on the influence of Gynostemma pentaphyllam Mak upon point mutation of Ha-ras oncogene in blocking leukoplakia from canceration].

OBJECTIVE: To study the influence of Gynostemma pentaphyllam Mak (GP) upon point mutation of Ha-ras oncogene the molecular mechanism of GP in blocking canceration, and the relationship between Ha-ras oncogene and canceration of leukoplakia. METHODS: DMBA induced carcinogeneses of the buccal pouch mucosa of the hamsters were divided into leukoplakia model group(LKG) and GP treated group(GPG). Point mutation (codon 61) of Ha-ras oncogene was detected by PCR-SSCP in both groups. RESULTS: The mutation incidence of LKG was 22.96%, while the mean incidence of GPG was 7.59% (The incidences of C20-OH group, glucoside group and aglucon group were 5.32%, 6.25% and 11.00% respectively). When treated with DMBA for 4 to 8 weeks, the mutation incidence of LKG ranged from 11.10% to 40.00%, while GPG ranged from 0 to 10.70%. CONCLUSIONS: GP has outstanding cancer blocking effect chiefly affected by free C20-OH. Mutation of Ha-ras oncogene plays an important role in leukoplakia canceration.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2000

[Detection of numerical chromosome aberrations in sperm of workers exposed to benzene series by two-color fluorescence in situ hybridization].

OBJECTIVE: To study the numerical aberrations of sex chromosomes in sperm of workers exposed to benzene series. METHODS: The interphase sperm from workers of exposed and control groups were hybridized using two color fluorescence in situ hybridization with X and Y(alpha)-satellite chromosome specific DNA probes, and the aneuploidy frequencies of X and Y chromosome in X and Y sperms were detected simultaneously. RESULTS: Geometric mean concentration of benzene in workplace air was 83.95 mg/m(3), one fold higher than national maximum allowable concentration. A total of 74,517 sperm nuclei in 13 benzene-exposed workers and 89,662 sperm nuclei in 13 control workers were counted. Frequencies of disomic sperm for X, Y and XY were (0.15 +/- 0.05)%, (0.13 +/- 0.05)% and (0.20 +/- 0.11)% in workers exposed to benzene series, and (0.10 +/- 0.04)%, (0.10 +/- 0.04)% and (0.13 +/- 0.06)% in control workers. There was statistical difference in disomic frequency of X sperm and overall disomic frequency between the benzene series-exposed workers (0.15% and 0.48%, respectively) and the control workers (0.10% and 0.33%, respectively). CONCLUSION: Exposed to benzene at higher concentration may induce increase in aneuploidy frequency of sperm sex chromosome in exposed workers.

Adult↗

PubMed2000

[Effect of green and yellow vegetables on serum carotenoid in children].

OBJECTIVE: To assay the effect of green and yellow vegetables on serum carotenoid concentration and its relation to serum retinol level in children. METHODS: A ten-week green and yellow vegetable intervention study was conducted in children aged 5.3 to 6.4 years of two classes in a kindergarten in Tai'an City of Shandong Province in early September 1996, one class of light-colored vegetable supplemented with daily 193 grams of light colored vegetables, such as cabbage, Chinese cabbage, potato, cucumber, cauliflower and turnip, and 56 grams of yellow-green vegetables, such as spinach, Chinese chive, carrots and red yams; and the other one of yellow-green vegetables with daily 238 grams of yellow-green vegetables and 34 grams of light colored vegetables, both without change in regular diet. Venous blood specimens were collected before and after the experiment from each of the subjects. Serum retinol and carotenoid were determined with high performance liquid chromatography. RESULTS: Serum level of carotenoid, including all-trans-beta-carotene, cis-beta-carotene, cryptoxanthin and lutein were significantly higher after intervention in yellow-green vegetable group, as compared to their baseline levels. However, in the light-colored vegetable group, all those components, including all-trans-beta-carotene, 13-cis-beta-carotene and lutein, decreased significantly after intervention, as compared with those at their baseline levels. Serum carotene level correlated significantly with that of retinol, and their coefficient of correlation was greater in the winter than in the autumn. CONCLUSION: Carotenoid nutrition status can be improved by supplementation of green and yellow vegetables.

Carotenoids↗

PubMed2000

[Effects of maxillary growth of Wistar rats with bilateral artificial cleft palate after premaxillary orthopedic treatment on expression of proliferating cell nuclear antigen(PCNA)].

OBJECTIVE: Being based on the principle of Latham's appliance, this experiment is designed to detect activity of osteoblasts in the maxillary sutures of Wistar rats with bilateral artificial cleft palate by immunohistochemistry technique, and evaluate the effects of this appliance on the growth and development of the maxilla. METHODS: The animal models of male infant Wistar rats with bilateral cleft palate were made by removing some palatal bones, splitting a "V" gap of 1.5 cm wide at the line between premaxilla and segments of maxilla. A sort of appliances, which could be fixed in the mouth of Wistar rats with bilateral cleft palate for correcting protrusion premaxilla was constructed basing on the principle of Latham's appliance. Then the diferent pathological changes of osteoblast proliferation between the experimental group and the two controlled groups were examined. The jugomaxillary sutrues, temporomalar sutures and sphenoipalatine suture were harvested 7, 14 days after premaxillar orthopedic treatment, followed by 4% paraformaldehyde fixing about 1 hour, demineralization with 15% EDTA and 0.5% paraformaldehyde for 48 hours, distilled water washing for a night, dimethylbenzene transparant dealing, and paraffin wax embeding. Proliferating Osteoblasts in all these sutures were investigated using immunohiostochemical technique with monoclonal antibodies of proliferating cell nuclear antigen (PCNA). RESULTS: Seven days after orthopedic treatment, no significant difference was observed between the experimental group and the two controlled groups. While after fourteen days, obvious PCNA-positive expression were observed in cells of all these sutures of the experimental group. CONCLUSION: The distribution of proliferating cells and the degree of cell proliferation change after premaxillary orthopedic treatment. And significant cell proliferation is observed in the experimental group, but there are no significant differences between the two controlled groups.

Animals↗

PubMed2000

[Studies on urinary metabolites of perlolyrine in rats].

OBJECTIVE: To study the metabolism of perlolyrine in rats, which is an active ingredient from the traditional Chinese herb, Ligusticum Wallichii Franch. METHODS: After administration of perlolyrine and deuterated perlolyrine, the rat urines were hydrolyzed with glucuronidase, basified with NaHCO3-Na2CO3, extracted with ethyl ether--iso-propyl alcohol. The organic phases (neutral and basic fractions) were concentrated for trimethylsilyl (TMS) derivatives. The aqueous phase were acidified with sulfuric acid, taken to dryness and extracted with methanol (water soluble acidic fractions) and concentrated for TMS derivatives. The TMS derivatives were determined by gas chromatograph mass spectrometry (GC-MS). RESULTS: Perlolyrine and one metabolite were found from the neutral and basic fractions, and two different metabolites were found from the water soluble acidic fractions. CONCLUSIONS: It was proposed that the major metabolic pathways of perlolyrine were that the hydroxylation of perlolyrine and the oxidation of its hydroxylmethyl group.

Animals↗

PubMed2000

[Spectroscopic properties of 7-hydroxyquinoline in polymeric matrices].

In this paper, the absorption and fluorescence spectra of 7-Hydroxyquinoline (7HQ) in the copolymer of methyl methacrylate (MMA) and methacrylic acid (MAA) monomers were observed. The influence of different matrices on the species of 7HQ and the excited state proton transfer effect were investigated. The results showed that, as the number of carboxylic group in the matrix was increased, the relative contents of different species of 7HQ should be changed and the excited state proton transfer effect of 7HQ was enhanced.

Adsorption↗

PubMed1999

Studies of the DXS7 polymorphism at the MAO loci in unipolar depression.

From the fact that DXS7 polymorphism is closely related to monoamine oxidase (MAO) genes and MAO inhibitors are widely used in the treatment of unipolar depression, it is of particular interest to study the relationship between the DXS7 polymorphism and unipolar depression. Thus, this study examined the possible association between DXS7 polymorphism and unipolar depression in 66 cases versus 85 controls from Shanghai. Polymerase chain reaction and amplification fragment length polymorphism techniques were used for genotyping of the DXS7 locus in this study. Four alleles at the DXS7 locus were detected with length generated by polymerase chain reaction amplification ranging from 157 to 167 bp. Comparison of allele frequency in the DXS7 locus showed no difference between unipolar depression cases and normal controls in the total population set. When subclassified by age, a significant difference of allele frequency distribution was observed between early onset (before age 40) and late onset (after age 40) patients. The frequency of the 157-bp allele was decreased, whereas the frequency of the 165 allele was increased in late onset patients (0.3810 for the 157-bp allele and 0.5238 for the 165-bp allele) compared with that of early onset patients (0.6304 for the 157-bp allele and 0. 3261 for the 165-bp allele). There was also a difference of allele frequency between patients and normal controls with age over 40 years. The frequency of 165-bp allele increased significantly in late onset patients (0.5238) compared with that of controls within the same age range (0.3454). Association studies suggested that in the population with age over 40 years, presence of the 165-bp allele of DXS7 locus was significantly associated with unipolar depression (relative risk = 2.08, P < 0.05), whereas in the total population set, this association did not exist. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:598-600, 1999.

Adolescent↗

PubMed1999

[The relation between alpha1-antichymotrypsin gene polymorphism and epsilon4 allele of apolipoprotein E gene in Alzheimer disease in Chinese]

OBJECTIVE: To detect the relation between alpha1-antichymotrpsin(AACT)gene polymorphism and epsilon4 allele of apolipoprotein E (ApoE) gene in Alzheimer disease (AD) in Chinese. METHODS: The gene polymorphisms of ApoE and AACT were genotyped in 125 AD cases and 140 controls with PCR methods and RFLP typing. Then the association between AACT polymorphism and ApoE epsilon4 was analysed. RESULTS: There was no association between AD and any allele or genotype of AACT polymorphism; AACT polymorphism was not associated with AD ApoE epsilon4 or without ApoE epsilon4. In AACT* AT and AACT* TT genotypes, ApoE epsilon4 allele was associated with AD, but no association was observed in AACT* AA genotype. CONCLUSION: AACT may not be associated with AD in Chinese, and this effect can not be influenced by ApoE epsilon4, but AACT gene polymorphism may affect the association between ApoE epsilon4 allele and AD.

Journal Article↗

PubMed1999

[Presinilin 1 gene polymorphism and Alzheimer's disease in Chinese].

OBJECTIVE: To detect the relationship between Presinilin 1(PS1) intronic polymorphism and Alzheimer's disease(AD) in Chinese. METHODS: PS1 intronic polymorphism was genotyped in 58 early-onset AD cases(EOAD), 65 late-onset AD cases (LOAD) and 157 age-matched controls by using PCR methods and RFLP typing. Then the association between PS1 polymorphism and AD was analyzed. RESULTS: (1) In EOAD cases, the frequency of allele 1 increased and the frequencies of allele 2 and genotype 2/2 decreased markedly, but in LOAD cases, no differences were observed. (2) EOAD was significantly associated with allele 1 (RR=2.29), P< 0.05), allele 2 (RR=0.44) and genotype 2/2(RR=0.23, P<0.05) of PS1 polymorphism, while LOAD showed no association with PS1 polymorphism. (3)PS1 polymorphism was associated with AD predominantly in non-ApoE epsilon4, female, early-onset cases. CONCLUSION: PS1 polymorphism was only associated with EOAD in Chinese, and this may be influenced by age of onset and sex.

Aged↗

PubMed1999

No association between the intronic presenilin 1 polymorphism and Alzheimer's disease in the Chinese population.

Wragg et al. [1996: Lancet 347:509-512] recorded an association between the intron-based presenilin 1 (PS1) genotype 1/1 and late-onset Alzheimer's disease (AD). This study was performed to determine if there is a similar association in the Chinese population. Ninety-one AD cases, 50 multiinfarct dementia (MID) patients, and 73 age-matched normal controls were recruited. Genotyping of PS1 and apolipoprotein E (APOE) was performed by the methods of polymerase chain reaction and restriction fragment length polymorphism. In AD, MID, and normal controls PS1 allele 1 frequency was 0.6703, 0.5600, and 0.6301, respectively; PS1 allele 2 frequency was 0.3297, 0.4400, and 0.3699, respectively. No association was detected between these diseases and any PS1 allele or genotype. There was only a nearly significant negative association between MID and PS1 genotype 1/1 in the subgroup population bearing APOE allele E4 (odds ratio = 0.2753, P = 0.0776). Our results do not support the conclusion that the intronic PS1 polymorphism is associated with Alzheimer's disease.

Aged↗

PubMed1999

Effects of nicotine on K+ channel currents in vascular smooth muscle cells from rat tail arteries.

Intake of nicotine has been related in many cases to acute or chronic hypertension. Using the patch-clamp technique the effect of nicotine on voltage-dependent K+ channel currents in rat tail artery smooth muscle cells was studied. Nicotine at concentrations of 1-100 microM or 0.3-3 mM increased or decreased, respectively, the amplitude of the tetraethylammonium-sensitive K+ currents. Pretreatment of cells with 10 microM dihydro-beta-erythroidine hydrobromide, a nicotinic receptor antagonist, abolished the excitatory effect (n=6), but not the inhibitory effect (n=10), of nicotine on K+ channel currents. The activation of nicotinic receptors with 100 microM 1,1-dimethyl-4-phenylpiperazinium iodide increased K+ channel currents by 27.4+/-3.8% (n=13, P < 0.01). Our results indicate that the excitatory and inhibitory effects of nicotine on K+ channels are respectively mediated by a nicotinic receptor-dependent mechanism and by a direct interaction of nicotine with K+ channels.

4-Aminopyridine↗

PubMed1999

Long-term depot-medroxyprogesterone acetate and bone mineral density.

The association between long-term use of depot-medroxyprogesterone acetate (DMPA) and bone mineral density (BMD) has been controversial, as seen in three case-control studies in New Zealand, Thailand, and the United Kingdom. In the present case-controlled study of BMD, a group of 67 Chinese women who had used DMPA from 5-15 years was compared with 218 women of the same age range who had not used any steroidal hormones. DMPA users were found to have a significantly lower BMD at lumbar vertebra (L2-4) (0.93 g/cm2), neck of femur (0.69 g/cm2), trochanter (0.59 g/cm2), and Ward's triangle (0.58 g/cm2), as compared with the control group, whose corresponding BMD values were 1.03 g/cm2, 0.83 g/cm2, 0.71 g/cm2, and 0.78 g/cm2, respectively (p < 0.001). The average percentage of bone loss per year was estimated to be 1.1% in L2-4, 2.3% in neck of femur, 2.4% in trochanter, and 3.5% in Ward's triangle. The percentage of bone loss in L2-4 was found to be more pronounced with age. This study provided information that the use of DMPA in a Chinese group for > 5 years in associated with bone loss, and a prospective study is needed to confirm these data, which are different from two case-control studies.

Absorptiometry, Photon↗