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Biomedical subjects

J Tang

Publications and source records attributed to J Tang.

At least 163 records · Page 9Linked to original sources
PubMed2000

Transgenic mice with increased hexosamine flux specifically targeted to beta-cells exhibit hyperinsulinemia and peripheral insulin resistance.

Hexosamines have been shown to mediate effects of hyperglycemia and so-called "glucose toxicity" in insulin-sensitive tissues. To determine the effects of hexosamines on insulin synthesis and secretion, transgenic mice were created to overexpress the rate-limiting enzyme for hexosamine synthesis, glutamine:fructose-6-phosphate amidotransferase (GFA), specifically in beta-cells. GFA activity in islets of heterozygous transgenic mice was elevated 76% compared with littermate controls. The increased GFA activity led to 1.4- and 2.1-fold increased pancreatic insulin content in 2- and 10-month-old transgenic mice, respectively (P < 0.005). Fasting insulin levels were 1.6-fold higher than in littermate controls (P < 0.05). Hyperinsulinemia was evident despite a 28% reduction in insulin mRNA levels. The fasting glucose levels in the transgenic mice equaled that of controls aged 2-4 months but exceeded that of the controls aged 6-10 months (means +/- SE 6.9 +/- 0.2 vs. 5.9 +/- 0.2 mmol/l, P < 0.001). By 8 months, the males were overweight and mildly diabetic (fasting glucose 8.8 +/- 0.5 mmol/l) despite persistent hyperinsulinemia. Insulin resistance was confirmed in both males and females using the euglycemic-hyperinsulinemic clamp technique; glucose disposal rates decreased by 48% in transgenic mice (P < 0.01). Triglyceride levels did not differ, and free fatty acid levels were lower in the transgenic animals. ATP levels were unchanged in the transgenic islets. We conclude that hexosamine biosynthesis is involved in the regulation of insulin content in beta-cells by glucose. Increased hexosamine flux in the beta-cell results in hyperinsulinemia, insulin resistance, and (in males) mild type 2 diabetes.

Animals↗
PubMed2000

[A convenient method of recovering DNA from agarose electrophoretic gels].

OBJECTIVE: Construct a simple unit to efficiently recover DNA from agarose electrophoretic gels. METHODS: With the use of 1.5ml microcentrifuge tube, 1 ml tip, nylon web membrane and dialysis membrane, the authors made a clever yet simple DNA recovering gadget, tested this gadget by using it to recover specific electrophoretic DNA bands of lambdaDNA/EcoR I+Hind III markers, and then examined the recovery ratio through agarose gel electrophoresis. A restriction enzyme's digestion product was taken as another sample to test the recovered product's quality by means of DNA ligation and subsequent agarose gel electrophoresis. RESULTS: Under such electroelution conditions as with an electrophoretic buffer of 1xTBE, a voltage grade of 3V/cm and an elution time of 0.5h, the final recovery ratio of 564bp DNA was up to 80%, and that of 21227bp DNA was about 30%. Judged either by the agarose gel electrophoresis performance or by the DNA ligation result, the recovered DNA proved to be of excellent quality. CONCLUSION: It is an easy, quick, efficient and cheap method of recovering DNA from agarose electrophoretic gels. The recovering unit can be a permanent one, provided that the dialysis membrane in this unit is changed for recovering different DNA samples.

DNA↗
PubMed2000

[The association between A55V variant in UCP2 gene and body fat distribution, serum lipid profile in Chinese].

OBJECTIVE: Uncoupling protein 2(UCP2) could play an important role in energy metabolism and body weight regulation. The aim of this study was to investigate Ala55Val(A55V) variant in the UCP2 gene has effects on serum lipid profile, body fat and its distribution in Chinese. METHODS: The genotypes of A55V variant in the UCP2 gene were determined by a PCR-RFLP assay in 359 unrelated Chinese [including 193 normal glucose tolerance(NGT) and 166 type 2 diabetic subjects by ADA 97' criteria]. The parameters for regional adipose tissue distribution were measured by magnetic resonance imaging(MRI). RESULTS: In NGT group, an association between A55V variant in the UCP2 gene and body mass index(BMI) (P=0.0246), as well as femoral subcutaneous adipose tissue area (FA) (P=0.0017), was noted in females. A55V variant in the UCP2 gene was also associated with serum triglyceride (TG) level (P=0.0072) in males. However, in type 2 diabetes group, an association between A55V variant in the UCP2 gene and FA (P=0.0150) was replicated in females too. Those females who were homozygotes of AA in the UCP2 gene had decreased FA not only in NGT group but also in type 2 diabetes group. Furthermore, logistic regression analysis indicated that FA (P=0.0098 in NGT females, P=0.0071 in type 2 diabetic females) and BMI (P=0.0016 in NGT females), as well as TG level (P=0.0040 in NGT males) were associated with this variant in the UCP2 gene. CONCLUSION: A55V variant in the UCP2 gene is associated not only with FA (in NGT females and type 2 diabetic females) but also with BMI (in NGT females). Therefore A55V variant in the UCP2 gene appears to play a role in body fat and its distribution in Chinese females.

Adipose Tissue↗
PubMed2000

[Genetic polymorphisms of eight STR loci in a Chinese Han population].

OBJECTIVE: To understand the allele structure and genetic polymorphism at eight STR loci in Chinese Han population and construct a preliminary database. METHODS: EDTA-blood specimens were collected from the unrelated individuals in Chengdu, China. The DNA samples were extracted with Chelex method and were amplified by PCR technique. The PCR products were analyzed by the PAG horizontal electrophoresis with discontinuous buffer system and by the approach of the automated fluorescence detection. RESULTS: Five STR loci consist of simple repeat motifs, while three STR loci contain complex repeat structures. The STR polymorphisms at all of the eight loci have been observed in Chinese Han population. According to the obtained data, the combined exclusion probability and the combined discrimination power for these STR markers in Chinese population are 0.9978 and 0.999 999 992, respectively. CONCLUSION: The obtained data are beneficial to understanding the population genetics of the eight STR loci in Chinese Han population. For forensic genetics, the obtained data can be used to calculate the probabilities dealing with the paternity test and the individual identification.

China↗
PubMed2000

[High-level expression of human vascular endothelial growth factor in Pichia pastoris].

The gene of VEGF165 was subcloned into the P. pastoris secretive expression vector pHIL-S1 and the recombinant expression plasmid pHIL-S1-VEGF165 was constructed. After transformation into yeast GS115, the positive transformants were obtained through phenotype selection and DNA Dot blotting. After induction by methanol, soluble dimer VEGF165 were expressed and secreted into the culture supernatant with its expression occupying 47% of the total protein in the supernatant. Dot blot analysis showed that the expressed human VEGF165 could bind to its receptors flt-1 and KDR.

Endothelial Growth Factors↗
PubMed2000

Response of capillary cell death to aminoguanidine predicts the development of retinopathy: comparison of diabetes and galactosemia.

PURPOSE: To examine the relationship between early retinal capillary cell apoptosis and late histologic lesions of diabetic retinopathy and to compare the effects of aminoguanidine (AMG) on the retinopathies caused by diabetes and galactose feeding. METHODS: Rats with alloxan-induced diabetes and rats fed a 30% galactose diet (known to induce diabetic-like retinopathy) were assigned randomly to receive diet with (2.5 g/kg diet) or without AMG. After 6 to 8 months of diabetes or galactosemia, retinal trypsin digests were prepared, and capillary cell apoptosis was quantitated using the Tdt-mediated dUTP nick-end labeling (TUNEL) reaction in association with morphologic evidence of nuclear fragmentation. At 18 months duration, pericyte ghosts and acellular capillaries were quantitated in the isolated vasculature. Several advanced glycation end products (AGEs) were measured at 4 months of study and at 18 months of study by established methods to assess biochemical effects of AMG. RESULTS: As expected, both diabetic and galactosemic rats showed increased frequency of TUNEL-positive capillary cells at 6 to 8 months and vascular lesions characteristic of retinopathy at 18 months. AMG inhibited both the early apoptosis and late histopathology in the diabetic rats, but neither of these abnormalities in the galactosemic rats. In contrast to its preventative effect on retinopathy in the diabetic rats, AMG showed no inhibitory effect on levels of hemoglobin AGE, or tail collagen pentosidine, fluorescence, and thermal breaking time. Diabetes of 4 months' duration did not cause a detectable increase in retinal levels of several AGEs. CONCLUSIONS: The frequency of early apoptosis in retinal microvascular cells predicted the development of the histologic lesions of retinopathy in diabetes as well as in galactosemia. The beneficial effect of AMG on retinal lesions in diabetes is exerted on pathways that are either not operative or are less important in galactosemia and that may not relate to the accumulation of AGEs.

Animals↗
PubMed2000

[Tolerance of various geographic populations of brown planthopper to adverse environmental stresses].

The populations of brown planthopper(BPH), Nilaparvata lugens, were collected from Zhejiang, Guangxi and Yunnan provinces to study their tolerance to various adverse environmental stresses. The results indicated that all of these three populations could adapt to the rice variety IR26 bearing resistant gene 1 (Bph1), and Guangxi and Yunnan populations could successfully infest rice varieties ASD7 bearing bph2 and Rathu Heenati bearing Bph3, implying that these two populations had a higher adaptability to resistant rice varieties. The significantly negative relationship between female brachypterous rate and nymphal density in Zhejiang population showed a lower tolerance to high nymphal density of Zhejiang population than that of Guangxi and Yunnan populations. A higher resistance to high temperature and a lower tolerance to starvation were obviously found in Guangxi and Yunnan populations. The resistance to insecticide (Omethoate) of Zhejiang population was little higher than that of Guangxi population. It was suggested that the tolerance of different geographic populations of BPH to various adverse environmental stresses be closely related to their habitat characteristics.

Animals↗
PubMed2000

Cloning of Chinese obese cDNA and its expression in E. coli.

OBJECTIVE: To obtain the sequence of Chinese obese (OB) cDNA and establish a method of leptin production in China. METHODS: Han Chinese OB cDNA fragment was obtained by reverse transcriptase-polymerase chain reaction (RT-PCR) with total RNA extracted from human adipocytes and was inserted into the expressing vector pBV220. Then the constructed recombinant plasmid pBV220-OB was transformed to E. coli DH5 alpha for leptin expression. The recombinant expressing system was confirmed by restriction endonuclease digestion, DNA sequencing and protein expression. E. coli cells were lysed by high-pressure homogenization. After cell membrane was extracted, the inclusion bodies were mainly renatured and purified primarily by precipitation with ammonium sulfate and gel chromatography through a Sephadex G75 column. The activity of recombinant leptin was determined by its influence on the satiety and weight gain of mice. RESULTS: Analysis of DNA sequence showed that Han Chinese OB cDNA included the glutamine codon at 49. The amount of recombinant leptin expressed in E. coli accounted for 31%-47% of total cellular proteins. From 1 L of fermentative bacteria about 40 mg of pure recombinant human leptin was isolated with a purity of being above 95%. The recombinant human leptin could reduce food intake and inhibit weight gains in mice. CONCLUSION: The glutamine codon at 49 is not missing in Chinese OB gene. The biologically active human leptin can be obtained by a relatively simple method of recombinant DNA technology.

Animals↗
PubMed2000

Stimulatory activity of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptors.

OBJECTIVE: To study the activity of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptors on cAMP production and inward calcium currents (Ica) in guinea pig ventricular myocytes. A comparison was also made with those of a muscarinic receptor agonist. METHODS: cAMP content was determined by radioimmunoassay and the Ica in guinea pig single ventricular cells were recorded by the whole-cell patch clamp technique. RESULTS: Both the muscarinic receptor agonist, carbachol (Carb 10 mumol/L), and anti-peptide antibodies (Abs 100 nmol/L) could decrease basal cAMP levels (by 46.9% +/- 4.2% and 60.2% +/- 4.6%, respectively) and basal Ica. Both Carb (10 mumol/L) and Abs (100 nmol/L) could also inhibit the isoprenaline-induced (Iso 0.8 mumol/L) increases in cAMP production (from 108.2 +/- 7.0 to 88.4 +/- 7.2 pmol/mg.protein/min for Carb and 88.6 +/- 5.1 pmol/mg.protein/min for Abs, respectively) and the increases in Ica. The muscarinic receptor antagonist atropine (Atr) was able to prevent these effects of Carb and Abs. CONCLUSIONS: Anti-peptide antibodies against an epitope located in the second extracellular loop of human M2 muscarinic receptors, similar to muscarinic receptor agonist, could decrease the basal Ica and beta-receptor agonist stimulated increase of Ica by decreasing the basal and beta-receptor agonist stimulated increase of cAMP production, and therefore could have an effect on their target receptor. These results further suggest that autoimmunity may participate in the pathogenesis of human cardiomyopathy and the second extracellular loop of human M2 muscarinic receptor could be the main immunodominant region.

Amino Acid Sequence↗
PubMed2000

Chinese-made electrolytic detachable coil in the embolization of a dog aneurysmal model.

OBJECTIVE: To develop a Chinese-made electrolytic detachable coil (CEDC) that would allow patients to enjoy the benefit of electrolytic detachable coil without having to rely on the expensive Guglielmi detachable coil (GDC), and to test the safety and efficiency of CEDC. METHODS: Radiopacity of the marker of the CEDC was tested. The anti-strain force of coils and connection points were measured. In vitro and in vivo electrolyses were conducted. We produced 21 aneurysm models including lateral, bifurcation, and terminal aneurysm models, and embolized 18 models with CEDC. RESULTS: Radiopacity of the marker was satisfactory. Anti-strain of the coil and the connection point have shown the safety and efficiency of CEDC. Electrolysis in vitro and vivo, was similar to that of GDC. 83% of the aneurysm models were completely occluded. Coils were found to induce thrombosis in the aneurysm cavity, and could lead to a new endothelium over the entrance of the aneurysm, with organized tissue replacing thrombosis in 2 months. CONCLUSIONS: CEDC is as efficient and safe as GDC. The marker, the ability to induce thrombosis inside the sac and the growth of new endothelium over the orifice are very satisfactory.

Animals↗
PubMed2000

[The inhibition of prourokinase gene transfer on deposition of platelets on rabbit carotid artery intima].

OBJECTIVE: To observe the expression of pro-urokinase (proUK) gene in rabbit carotid artery transfected with replication-deficient adenovirus vector containing proUK gene (Ad/prouk) and the deposition of platelet on the same injured vessel. METHODS: Ad/proUK (Ad/proUK, 3 x 10(10) pfu/ml) was injected into the right carotid artery locally. Wild type adenovirus (Ad) was locally injected into the left carotid artery as self-control. The expression of proUK gene was investigated by immunohistochemistry assay. After injury of the gene-transfected vessel by electric stimulation, the deposition of (111) In-labeled platelet was quantitatively observed. The thrombosis was observed with HE-stained vessel section. RESULTS: There were lots of proUK granules in the endothelium of Ad/proUK gene-transfected vessel. The differences in (111) In-platelets deposition per gram dry weight vessel segment were significant between Ad/proUK and Ad transfected control vessels [(4.60 +/- 0.93) x 10(7)/g vs control (27.95 +/- 4.93) x 10(7)/g, P < 0.01)]. The HE-stained vessel section showed that there were only small thrombi in proUK gene-transfected vessel but massive thrombi almost blocked up the whole vessel in control vessel. CONCLUSION: The proUK gene-transfected vessel can obviously inhibit (111) In-labeled platelet deposition on injured vessel and thus thrombosis.

Adenoviridae↗
PubMed2000

[Plasmid pcDNA3 enhances Ca(2+) transport of sarcoplasmic reticulum in ischemic skeletal muscle of rats].

The effects of plasmid pcDNA3 on Ca(2+) transport of sarcoplasmic reticulum (SR) in ischemic skeletal muscle was investigated. The results show that Ca(2+) transport (including Ca(2+) uptake and Ca(2+) release) rate of SR in ischemic skeletal muscle was markedly increased compared with that in non-ischemic muscle (P<0.01 or P<0.05). After plasmid pcDNA3 bound to the DNA binding proteins of SR, Ca(2+) transport of SR was further increased. The results suggest that the effect of plasmid DNA on the ability of Ca(2+) transport in SR of ischemic skeletal muscle is the same as is observed in normal skeletal muscle. The pathophysiological significance of the present finding deserves further exploration.

Animals↗
PubMed2000

[A study on the clinical classification of oral submucous fibrosis].

OBJECTIVE: To increase the positive rate and sensitivity of the diagnosis for oral submucous fibrosis (OSF). METHODS: A general oral survey of 11,046 persons was carried out in Xiangtan, Hunan. According to Pindborg's diagnostic standard to epidemiological studies of OSF, 335 cases of OSF were found. The prevalence was 3%. According to different clinical manifestations, 335 cases of OSF were divided into two types: diffuse type and localized type. The cases with typical features of OSF, such as burning pain and discomfort, dryness of the mucosa, progressive inability to open the mouth and presence of palpable bands in the oral mucosa and so on, were in the diffuse type. Those with non-typical features, only having presence of palpable bands in the oral mucosa, were in the localized type. 72 cases were followed-up for ten years. RESULTS: 335 cases of OSF were divided into two types. 13 cases (3.9%) were in the diffuse type, and 322 cases (96.1%) were in the localized type. Most of the OSF in this region belonged to the localized type. It was also discovered that without proper treatment, the subjects sticked to one type of OSF without changing from one type to another after ten years of follow-up. CONCLUSION: Localized type of OSF is the major type of OSF in Xiangtan. It is an independent clinical type. To classify OSF, it is good for the clinicians to pay attention to non-typical OSF. If the non-typical OSF cases are taken into consideration, the prevalence of OSF will increase considerably.

China↗
PubMed2000

[Prevention and release of epidural-morphine-induced urinary retention with phenoxybenzamine and neostigmine].

OBJECTIVE: To study the effects of preoperative phenoxybenzamine (o.p) on preventing epidural-morphine-induced urinary retention and effects of neostigmine on releasing it. METHODS: 80 patients who received epidural morphine to release postoperative pain were divided into 4 groups randomly and received preoperative phenoxybenzamine (group P, n = 20), neostigmine (i. m) when urinary retention happened (group N, n = 20), both drugs (group U, n = 20), and without drugs (Control, n = 20), respectively. The incidences of urinary retention and release were observed. RESULTS: No significant decrease (P > 0.05) happened after operation in the incidence of epidural-morphine-induced urinary retention both in the group P and in the group N. Neostigmine(i. m) could significantly release (P < 0.001) the epidural-morphine-induced urinary retention when phenoxybenzamine was administrated preoperatively. CONCLUSION: Preoperative phenoxybenzamine can not prevent epidural-morphine-induced urinary retention. Neostigmine can release the urinary retention only when preoperative phenoxybenzamine is used.

Adolescent↗
PubMed2000

[Re-evaluation of an embolic material for aneurysm cellulose acetate polymer].

OBJECTIVE: To re-evaluate the safety, effect, and pathological reactions of cellulose acetate polymer (CAP). METHODS: 30 right carotid arteries of rats were embolized and got two embolized vessels for histological study in each of the seven stages within four months. Fifteen canine aneurysmal models were created by transplantation of venous pouches. Twelve of them were occluded with CAP. Digital Subtraction Angiography (DSA) follow-ups of occluded aneurysmal models were carried out 1, 2 and 8 weeks after occlusion. One animal was sacrificed randomly at each stage for pathological study. RESULTS: Only five of the 12 aneurysmal models were completely or partially occluded within the patency of parent arteries within two months of observation after embolization with CAP. Stenosis of one branch of aneurysmal parent artery was occurred. The residual cavity of one partially occluded model artery was enlarged. Two models ruptured on four and five days after embolization. Three embolized models and their parent arteries were all occluded. PATHOLOGICAL FINDINGS: acute pathological reaction occurred within vessels embolized with CAP. Endothelial cell and basal membrane were damaged and vanished. Elastic lamina was exposed to arterial lumen and attached by thrombus layer. Fibrous cells and smooth muscle cells showed obvious degeneration. CAP and thrombus were gradually organized in two months after thrombosis. The orifices of aneurysmal models were covered with newly developed fibrous tissue and endothelial cells in two months after thrombosis. CONCLUSIONS: We think that acute chemical erosive effect of CAP was evident. A strong effect could lead to rupture of some of the CAP thrombosed aneurysmal models. Besides, stenosis or occlusion of the parent arteries could be induced in some cases after embolization with CAP. For the above shortcomings and limitations, it should be improved carefully before it is applied in clinic.

Aneurysm↗
PubMed2000

[A novel apoptotic related gene--homocysteine-induced gene HCY-2].

OBJECTIVE: To investigate the mechanisms resulting in cardiovascular diseases and birth defect. METHODS: Induced screening and differential display, Northern blot, and immunohistochemistry assay were applied to clone the homocysteine-induced gene HCY-2 and detect the expression of HCY-2 gene respectively. RESULTS: A novel HCY-induced full length cDNA--HCY-2 which encodes 142 amino acids was obtained from vascular smooth muscle cells of rats. Results of the Northern blot and immunohistochemistry assays suggest that it widely expresses in many kinds of tissues such as heart, kidney, brain, liver, and lung. In vitro, we transferred recombinant HCY-2 gene into endothelial cells and found that it could induce apoptosis and DNA injury. In vivo, HCY-2 gene could induce chicken embryo cells apoptosis and embryo malformation. CONCLUSIONS: The results indicated that HCY-2 gene might be a novel apoptosis-inducing gene and might be involved in the pathogenesis of cardiovascular diseases and birth defects induced by hyperhomocysteinemia.

Amino Acid Sequence↗