Biomedical subjects

G Wu

Publications and source records attributed to G Wu.

At least 487 records · Page 27Linked to original sources

PubMed1995

Effects of different sampling strategies on predictions of blood cyclosporine concentrations in haematological patients with multidrug resistance by Bayesian and non-linear least squares methods.

The Bayesian method (BM) can use previous information for the optimization of dosage regimen. However, Bayes' law remains true when the parameters are obtained from the infinite population. Therefore a bias might exist in the previous information and affect BM predictive performance. To overcome this shortcoming, the blood drug concentration of a patient can be used to individualize his pharmacokinetic parameters. Until now, at least two sampling strategies, i.e. steady-state and non-steady-state sampling strategies, have been developed to individualize and predict blood drug concentration. In the present study we used five sampling strategies: (1) all samples; (2) post-infusion samples; (3) during-infusion samples; (4) samples within 95% confidence interval/interquartile range of a steady-state concentration; (5) the sample of the mean/median at the mid-time-point of a steady-state to individualize and predict blood cyclosporine concentrations in haematological patients with multidrug resistance. We investigated the effects of different sampling strategies on BM and the nonlinear least squared method (NLLSM) predictive performances. The results showed that BM predictive performance was better than NLLSM. But the results did not prove that the steady-state sampling strategies were superior to the non-steady-state ones.

Adult↗

PubMed1995

GM1 ganglioside in the nuclear membrane modulates nuclear calcium homeostasis during neurite outgrowth.

GM1 in the nuclear membrane, previously shown to be up-regulated during neurite outgrowth, has been found to influence nuclear Ca2+ flux during differentiation of Neuro-2a cells. Nuclei were isolated from cultured Neuro-2a cells before and after neuraminidase-induced neuritogenesis and incubated with 45Ca2+ for varying periods to determine uptake/efflux of Ca2+. At 5, 10, and 15 min 45Ca2+ levels in nuclei from differentiated cells were significantly lower than those in nuclei from untreated cells. The same result was obtained when the GM1 level was elevated artificially by preincubation of the nuclei in 10 microM GM1. In experiments designed to measure efflux specifically, isolated nuclei preincubated in GM1 released 45Ca2+ more rapidly than untreated nuclei. We conclude that one role of GM1 in the nuclear membrane is to alter Ca2+ regulatory mechanisms in the nucleus following onset of neuronal process outgrowth.

Adenosine Triphosphate↗

PubMed1995

Developmental changes of free amino acid concentrations in fetal fluids of pigs.

Free amino acid concentrations were determined in amniotic and allantoic fluids and in fetal and maternal uterine plasma of pigs during gestation. Glycine and glutamine were the most abundant free amino acids in maternal uterine arterial and fetal umbilical venous plasma, respectively. Plasma fetal/maternal ratios were remarkably < 1 for glycine, > 2 for glutamine and = 1 for total free alpha-amino acids. Glutamine was the most abundant free amino acid in amniotic fluid during the first 3 mo of gestation. The concentrations of most amniotic fluid amino acids progressively decreased with increasing gestational age from 45 to 110 d. Glycine was the most predominant amino acid in allantoic fluid on d 30 of gestation but decreased on d 45 and 60 of gestation. This decrease in allantoic fluid glycine coincided with a marked increase in concentrations of both ornithine and arginine, which accounted for 34-36% of total free alpha-amino acids in allantoic fluid. Such an abundance of ornithine and arginine in allantoic fluid has not been reported for any other biological fluid. On d 90 and 110 of gestation, glycine again became the most abundant amino acid in allantoic fluid, or 47 and 29% of total free alpha-amino acids, respectively. Urea concentrations in amniotic and allantoic fluids progressively increased during the second half of pregnancy, indicating enhanced fetal protein metabolism. Our results demonstrate the abundance of glutamine in fetal plasma, the unusual abundance of ornithine, arginine and glycine in allantoic fluid and developmental changes in plasma fetal/maternal ratios of amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1995

The induction of citrulline synthesis from glutamine in enterocytes of weaned pigs is not due primarily to age or change in diet.

This study was designed to determine the roles of age and diet in the induction of citrulline synthesis from glutamine in enterocytes of weaned pigs. Enterocytes were prepared from the jejunum of suckling pigs (14-29 d old), 23- and 29-d-old pigs weaned at 21 d of age to either a conventional corn-soybean meal-based or a milk-based diet, and 23-d-old pigs weaned at 21 d of age and food-deprived for 2 d. Cells were incubated at 37 degrees C for 30 min in Krebs-Henseleit bicarbonate buffer (pH 7.4) in the presence of 5 mmol/L glucose with or without 2 mmol/L glutamine. The rate of citrulline production from glutamine was similar in enterocytes from 14-, 21- and 29-d-old suckling pigs, and was 10-fold greater in cells from 29-d-old weaned pigs. After weaning, enterocytes from 23-d-old pigs fed the milk-based diet had a 33% higher rate of citrulline production from glutamine than cells from age-matched pigs fed a corn-soybean meal-based diet or food-deprived for 2 d. Our findings suggest that the major determinant of the induction of citrulline synthesis from glutamine in enterocytes of weaned pigs may not be age or change in diet, although the extent of the induction may be slightly influenced by diet composition.

Aging↗

PubMed1995

Disease resistance conferred by expression of a gene encoding H2O2-generating glucose oxidase in transgenic potato plants.

Plant defense responses to pathogen infection involve the production of active oxygen species, including hydrogen peroxide (H2O2). We obtained transgenic potato plants expressing a fungal gene encoding glucose oxidase, which generates H2O2 when glucose is oxidized. H2O2 levels were elevated in both leaf and tuber tissues of these plants. Transgenic potato tubers exhibited strong resistance to a bacterial soft rot disease caused by Erwinia carotovora subsp carotovora, and disease resistance was sustained under both aerobic and anaerobic conditions of bacterial infection. This resistance to soft rot was apparently mediated by elevated levels of H2O2, because the resistance could be counteracted by exogenously added H2O2-degrading catalase. The transgenic plants with increased levels of H2O2 also exhibited enhanced resistance to potato late blight caused by Phytophthora infestans. The development of lesions resulting from infection by P. infestans was significantly delayed in leaves of these plants. Thus, the expression of an active oxygen species-generating enzyme in transgenic plants represents a novel approach for engineering broad-spectrum disease resistance in plants.

Base Sequence↗

PubMed1995

Screening of potential transport systems for methyl mercury uptake in rat erythrocytes at 5 degrees by use of inhibitors and substrates.

The current study was designed to screen the potential transport systems for methyl mercury (MeHg) uptake by isolated erythrocytes from rats at 5 degrees. Several inhibitors and substrates were used to test which potential transport system might be involved in MeHg uptake. Probenecid was used to test the organic anion transport system, valinomycin was used to test the effect of the membrane potential, D-glucose and cytochalasin B were used to test the facilitated diffusive D-glucose transport system and colchicine and vinblastine were used to test the microtubule system. The effects of Ca++, Mg++ and Na+ on MeHg uptake have been examined. Ouabain, ATP and glucose were used to test the active transport system, cysteine for the cysteine-facilitated transport system, glycine for system Gly, DL-methionine for system L, and MeHgCl and 4',4-diisothiocyano-2',2-stilbenedisulfonic acid (DIDS) for the Cl- ion transport system. The results showed that MeHg uptake might be involved in the following transport systems at 5 degrees: 1) organic anion transport system; 2) facilitated diffusive D-glucose transport system; 3) cysteine-facilitated transport system; 4) Cl- ion transport system. Moreover, the transport systems for MeHg uptake were sensitive to the membrane potential. Although the mechanisms of interaction of transport systems have not been fully clarified, evidence has been presented which support the existence of several simultaneous transport systems for MeHg uptake.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1995

Characterization of the cycHJKL genes involved in cytochrome c biogenesis and symbiotic nitrogen fixation in Rhizobium leguminosarum.

Mutants of Rhizobium leguminosarum bv. viciae unable to respire via the cytochrome aa3 pathway were identified by the inability to oxidize N,N'-dimethyl-p-phenylenediamine. Two mutants which were complemented by cosmid pIJ1942 from an R. leguminosarum clone bank were identified. Although pea nodules induced by these mutants contained many bacteroids, no symbiotic nitrogen fixation was detected. Heme staining of cellular proteins revealed that all cytochrome c-type heme proteins were absent. These mutants lacked spectroscopically detectable cytochrome c, but cytochromes aa3 and d were present, the latter at a higher-than-normal level. DNA sequence analysis of complementing plasmids revealed four apparently cotranscribed open reading frames (cycH, cycJ, cycK, and cycL). CycH, CycJ, CycK, and CycL are homologous to Bradyrhizobium japonicum and Rhizobium meliloti proteins thought to be involved in the attachment of heme to cytochrome c apoproteins; CycK and CycL are also homologous to the Rhodobacter capsulatus ccl1 and ccl2 gene products and the Escherichia coli nrfE and nrfF gene products involved in the assembly of c-type cytochromes. The absence of cytochrome c heme proteins in these R. leguminosarum mutants is consistent with the view that the cycHJKL operon could be involved in the attachment of heme to apocytochrome c.

Amino Acid Sequence↗

PubMed1995

Improvement by guan-mu-tong (Caulis aristolochiae manshuriensis) of lactation in mice.

Free access of 0.5% Guan-mu-tong (Gmt) as drinking water inhibited lactation of mice estimated by pup growth rate, which was associated with a decrease in RNA content and RNA/DNA ratio in the mammary glands. 0.05% Gmt improved pup growth rate and mammary DNA content. No pups were lost during the experiment. Similar results were obtained by 0.5% Xia-ru-yong-quan-tang (Xryqt), a Chinese herbal medicine, which contained 0.05% Gmt. Xryqt further prevented a decline in ovarian weight seen by 0.05% Gmt treatment and significantly increased mother weight. These findings revealed two opposite effects of Gmt on mammary glands, stimulative and inhibitory, at low- and high-dose levels, respectively.

Animals↗

PubMed1995

Humoral factor(s) in hypertensive rats trophic for cultured aortic smooth muscle cells.

Humoral factors in one-kidney, one-clip (1K,1C) hypertension in rats increase growth of smooth muscle cells cultured from rat arteries. To further characterize the plasma factor or factors involved, we prepared male rats with early, benign 1K,1C hypertension and paired them with one-kidney (1K) normotensive controls. In the presence of growth stimulated by background levels (1%) of fetal calf serum (FCS), plasma-derived serum (PDS), fresh or frozen, from 99 1K,1C rats differentially increased [3H]thymidine incorporation of growth-arrested rat aortic cells; increases were up to 93% more than those evoked by the paired 1K PDS and were concentration related (P < 0.01). However, there was no evidence for a differential effect of 1K,1C PDS in the absence of FCS nor of PDS after boiling. On the other hand, neither treatment of PDS with proteolytic enzymes nor charcoal absorption ablated this differential trophic effect. Thus this study provides evidence that the humoral factor(s) in hypertension are resistant to freezing, proteolysis, and charcoal absorption, but sensitive to boiling, and they require background levels of growth for expression.

Animals↗

PubMed1995

Impaired arginine metabolism and NO synthesis in coronary endothelial cells of the spontaneously diabetic BB rat.

Arginine metabolism via nitric oxide (NO) synthase and other pathways was studied in coronary endothelial cells (EC) from the spontaneously diabetic BB rat, an animal model of human type I diabetes mellitus (IDDM). EC were prepared from insulin-treated diabetic BB (BBd) and non-diabetes-prone BB (BBn) rats. Basal NO synthesis was studied in EC cultured for 48 h in medium containing 0.4 mM L-arginine. At the end of the culture period, the medium was analyzed for nitrite and nitrate (two major end stable oxidation products of NO), and the cells were used to determine arginine uptake and metabolism and the activities of some arginine-degrading enzymes. For studies of arginine metabolism, cells were incubated at 37 degrees C for 1 h in Krebs-Henseleit bicarbonate buffer (pH 7.4) containing 1 mM L(-)[1-14C]arginine or L(-)[1-14C]ornithine. The rates of production of nitrite plus nitrate by BBd EC were only 15% of those of BBn cells. This impaired NO synthesis in BBd EC was not due to alterations in arginine uptake, NO synthase activity, or intracellular arginine concentrations but might have resulted from a limited intracellular availability of cofactors of NO synthase. In addition to the arginine-NO pathway, arginine was found to be metabolized to urea, ornithine, and, to a much lesser extent, CO2 via arginase and ornithine aminotransferase. The activities of arginase and the formation of ornithine and urea from arginine were decreased by 90% in BBd compared with BBn cells. These results, coupled with the reduced NO synthesis, indicate metabolic defects in arginine metabolism in BBd EC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Glutamine and glucose metabolism in enterocytes of the neonatal pig.

Glutamine and glucose metabolism was studied in 0- to 21-day-old pig enterocytes. Cells were incubated at 37 degrees C for 30 min in Krebs-Henseleit bicarbonate buffer (pH 7.4) in the presence of 2 mM [U-14C]glutamine with or without 5 mM glucose, or 5 mM [U-14C]glucose with or without 2 mM glutamine. Glutamine was metabolized to ammonia, glutamate, alanine, aspartate, CO2, citrulline, ornithine, and proline, whereas glucose was converted to lactate, pyruvate, and CO2 in pig enterocytes. CO2 production from glutamine accounted for 32-36% and 3-4% of utilized glutamine carbons in 0- to 7-day-old and 14- to 21-day-old pigs, respectively. The rates of O2 consumption and metabolism of glutamine and glucose decreased in enterocytes from 2- to 14-day-old pigs compared with 0-day-old pigs. By day 14 after birth, the oxidation of glutamine and glucose as well as citrulline production had decreased by 90-95%. Arginine synthesis from glutamine occurred in cells from 0- to 7-day-old pigs but not 14- to 21-day-old ones. Glucose (5 mM) had no effect on glutamine utilization and oxidation or the production of glutamate and arginine but stimulated the formation of alanine, citrulline, and proline at the expense of aspartate. In contrast, glutamine (2 mM) inhibited glycolysis and glucose oxidation in cells from 0- to 7-day-old pigs and had no effects in 14- to 21-day-old pigs. As a result, glutamine contributed approximately 2-fold greater amounts of ATP to 0- to 7-day-old pig enterocytes than glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1995

Arginine synthesis in enterocytes of neonatal pigs.

Arginine is deficient in porcine colostrum and milk, and yet the piglet has a particularly high requirement for this essential amino acid for rapid postnatal growth. To explain this paradox, arginine synthesis was quantified in enterocytes from newborn (0-day-old) and 2- to 7-day-old suckling pigs. Arginine was found to be synthesized from glutamine in 0- to 7-day-old pig enterocytes, but the rates of arginine synthesis were three- to fourfold greater in 0- to 2-day-old pigs than in 7-day-old pigs. To elucidate the developmental change of the intestinal arginine synthesis, the metabolism of glutamine to citrulline, the conversion of citrulline to arginine, and the activities of the enzymes involved were measured. The rates of metabolism of glutamine to citrulline were 2.5- to 3.5-fold greater in enterocytes from 0- to 2-day-old pigs than in cells from 7-day-old pigs, as were the rates of conversion of citrulline to arginine. The activities of all enzymes that synthesize arginine from glutamine, except pyrroline-5-carboxylate synthase and argininosuccinate lyase (ASL), increased in enterocytes from 2-day-old pigs compared with 0-day-old pigs. The activities of all these enzymes decreased by approximately 75% in 7-day-old pigs compared with 2-day-old pigs. Arginase activity was negligible in enterocytes from 0- to 7-day-old pigs, thus minimizing intestinal hydrolysis of newly synthesized arginine and maximizing the endogenous provision of arginine. The results of this study demonstrate the presence of arginine-synthesizing enzymes and their developmental changes in postnatal pig enterocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1995

Nitric oxide synthesis and the effect of aminoguanidine and NG-monomethyl-L-arginine on the onset of diabetes in the spontaneously diabetic BB rat.

Nitric oxide (NO) synthesis and the effect of aminoguanidine (AG) and NG-monomethyl-L-arginine (NMMA) (inhibitors of NO synthase) on the onset of diabetes were studied in the spontaneously diabetic BB rat. To measure in vivo NO production, 20 male 50-day-old diabetes-prone BB (BBdp) rats and age-matched non-diabetes-prone BB (BBn) rats were individually placed in metabolism cages. The animals had free access to a casein-based semipurified diet and deionized and double-distilled water. Urine excretion was collected every other day for 70 days, and urinary excretion of nitrate was measured as an index of in vivo NO synthesis. The urinary excretion of nitrate was enhanced by 150-200% in BBdp rats 4-6 days before the onset of diabetes, compared with aged-matched BBn rats. There was no difference in urinary excretion of nitrate between BBn rats and those BBdp rats that did not develop diabetes by the age of up to 120 days. To determine a role of NO in the development of spontaneous diabetes, 40-day-old male BBdp rats (30 rats per group) received daily subcutaneous injections of NMMA (acetate salt) (5 mg/kg body wt) or equal amounts of acetate (control) or oral administration of AG (0 or 3 g/l of drinking water) for 80 days. Both NMMA and AG delayed the onset of diabetes in BBdp rats by 13-15 days without altering the rate of incidence of diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1995

Humoral factors trophic for vascular smooth muscle during the development of hypertension in rats.

There is evidence that a humoral factor or factors in rats with one-kidney, one-clip (1K1C) hypertension increase growth of cultured vascular smooth muscle cells. Such humoral trophic factors may contribute to the abnormal growth of arterial muscle in hypertension. To further study the longitudinal expression of this trophic factor or factors, we prepared rats with 1K1C hypertension of different durations. To determine if the factor or factors are also expressed in other forms of experimental hypertension, we additionally prepared rats with two-kidney, one-clip (2K1C) hypertension and paired two-kidney (2K) normotensive controls; we also studied Spontaneously Hypertensive Rats (SHR) plus appropriate controls. In the presence of growth stimulated by background levels (1%) of fetal calf serum, 20% platelet-poor, plasma-derived serum (PDS) from 1K1C rats 8-14 days (n = 10) and 28 days (n = 12) after clipping increased [3H]-thymidine incorporation of growth-arrested cultured rat aortic smooth muscle cells more than the paired 1K PDS, by up to +67% and +40%, respectively (P < 0.01). However, with PDS from 1K1C rats 4 days (n = 11) and 38 days (n = 6) after clipping there was no evidence for a differential effect (P > 0.5 and P > 0.1, respectively). PDS from seven 2K1C rats (at 9 days) also increased [3H]-thymidine incorporation of the assay cells more than PDS from the paired 2K rats, by up to +19% (P < 0.05). However, there was no evidence that PDS from SHR differentially increased cellular thymidine incorporation. Thus, evidence from this study suggests that the humoral factor or factors trophic for vascular smooth muscle are expressed in both low- and high-renin forms of experimental renovascular hypertension, but not in the very early or in the late complicated stages of the hypertension, or in genetic hypertension in rats.

Animals↗

PubMed1995

[Textual research on genealogy and related problems of Xu Lingtai].

This paper deals with Xu Lingtai's genealogy from his grand-grand father down to six generations with the short biographical acounts of each generation. From these, one can learn the origin, development of the literary and medical aspects of Xu's family. It also discusses the name, nickname, other names, dates of birth and death, tombs of Xu Lingtain by studies on relics and literatures, intending to solve the puzzles and errors of the above problems.

China↗

PubMed1995

[The value of serum myelin basic protein in assessment of severity of acute closed head trauma].

Serum levels of myelin basic protein (MBP) were measured in 112 patients after acute head injury by enzyme linked immuno-absorbent assay (ELISA). Patients with cerebral concussion showed no significant change in serum MBP. Patients with cerebral contusion, extradural hematoma or intracerebral hematoma had a mean serum MBP concentration much higher than that of patients with cerebral concussion. And patients with extradural hematoma had a mean serum MBP concentration much lower than that of patients with cerebral contusion and intracerebral hematoma; the differences were significant (P < 0.05). But there was no significant difference between patients with cerebral contusion and intracerebral hematoma (P > 0.05). The amount of serum MBP was significantly correlated with the volume of extradural hematoma, intracerebral hematoma and with the extent of the cerebral contusion (P < 0.05). This study suggested that the serum MBP may reflect the type and severity of closed head injury patients.

Adolescent↗

PubMed1995

[Analysis of hepatitis B virus X antigen expression in chronic hepatitis B and cirrhosis].

It has been shown that hepatitis B virus (HBV) X antigen (HBxAg) functioned as a transactivating element which can act on the enhancer of HBV in an in vitro system and elevate the transcriptional level of HBV. In this study we investigate the relationship between HBxAg expression and HBV replication in patients with chronic hepatitis B and cirrhosis. Rabbit IgG against recombinant HBxAg which was synthesized in E. coli were prepared and used for the detection of HBxAg. HBV DNA was amplified by polymerase chain reaction technique by using primers from HBx gene sequence. Liver tissue samples and sera from the patients were examined immunohistochemically for HBxAg and serologically for HBxAg/anti-HBx respectively. We focused on its expression in these samples in comparison with markers of HBV replication. It was found that in liver HBxAg was present in 72.7% of the patients with chronic active hapatitis (CAH) and 92.6% of those with cirrhosis, while the positivity rate of HBcAg in cirrhosis patients was only 47.8%. In the sera of the patients with CAH, chronic persistant hepatitis and cirrhosis HBxAg was present in 44.4%, 66.6% and 33.3% respectively. It was similar to that observed with HBeAg. Moreover in these HBxAg positive sera HBV DNA can also be detected. It was shown that higher rate of positivity of HBxAg was found in patients with replicative markers (serum HBeAg, serum HBV DNA or liver tissue HBcAg positive). Our results indicate that expression of HBxAg is closely correlated with HBV replication and HBxAg may be an important marker in chronic HBV infection.

Animals↗

PubMed1995

[Effect of intralipid on patients with acute necrotic pancreatitis: a prospective clinical study].

17 patients with acute necrotic pancreatitis were proved by CT or operation. These patients were randomly assigned to fat-glucose-based group (n = 9) and glucose-based group (n = 8). Their PN regimen consisted of nonprotein calories (NPC) 35-40KJ (146-167KJ)/kg/d and nitrogen 0.19-0.29g/kg/d. NPC was supplied by either dextrose or dextrose and intralipid. The PN duration was 2 weeks. The following measurements were performed: triglyceride, chorestrol, HDL, LDL, Apo-A, Apo-B and free fatty acids. The results showed that there was no hypertriglyceridemia developed after fat emulsion was administered for two weeks. It confirmed that fat emulsion could be rapidly oxidigzed. In our group, the patients with hyperglycemia were 64% at the admission time, and hyperglycemia was difficult to control in early period (10 days). But hyperglycemia was easly to control when patients received fat emulsion. There was no harmful effect on liver function during 2 weeks of intralipid administration. The data showed no difference between the two groups on conventional measurements, lysosomal enzymes and blood gas analysis. Intralipid infusion did not make ANP deterioration. These results indicated long-term intravenous intralipid in patients with ANP was safe and useful.

Acute Disease↗