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Biomedical subjects

L Zhao

Publications and source records attributed to L Zhao.

At least 397 records · Page 22Linked to original sources

Effect of 2,3-butanedione monoxime on myocyte resting force during prolonged metabolic inhibition.

The chemical phosphatase 2,3-butanedione monoxime (BDM) has been reported to inhibit both Ca(2+)-induced myofilament force development and rigor due to ATP depletion. However, during prolonged hypoxia in cultured ventricular myocytes BDM delays but does not prevent a marked increase in resting force. To investigate the mechanisms involved we measured the effects of BDM on intracellular Ca2+ concentration ([Ca2+]i; indo 1), force development (video motion detector), and ATP contents (luciferase assay) in cultured embryonic chick ventricular myocytes and adult rabbit ventricular myocytes subjected to prolonged metabolic inhibition with 1 mM NaCN and 20 mM 2-deoxyglucose. In the absence of metabolic inhibition, 20 mM BDM depressed force development even when [Ca2+]i was markedly elevated by exposure to zero-Na solution or 10 mM caffeine in chick cells, and 30 mM BDM completely inhibited Ca(2+)-induced force development in rabbit myocytes. During metabolic inhibition, 20 mM BDM delayed the onset of an increase in resting force (from 5.44 +/- 0.87 to 13.67 +/- 1.34 min in chick myocytes; from 19.13 +/- 2.23 to 32.43 +/- 3.30 min in rabbit myocytes, means +/- SE, n = 8-9). However, the rates of ATP depletion and rise in [Ca2+]i after metabolic inhibition were not altered by BDM. In the presence of BDM, during prolonged metabolic inhibition in both chick and rabbit myocytes, abrupt spontaneous or evoked alterations in [Ca2+]i were associated with corresponding changes in force. During the initial increase in resting force induced by metabolic inhibition, exposure to BDM caused a partial transient relaxation. We conclude that the delayed increase in resting force during metabolic inhibition in the presence of BDM is due to redevelopment of Ca2+ sensitivity of the myofilaments in the presence of an increased [Ca2+]i as a consequence of severe ATP depletion, whereas in the absence of BDM the more rapidly developing increase in resting force during metabolic inhibition is initially due to a rise in [Ca2+]i followed by development of rigor.

Adenosine Triphosphate↗

Reduced mercury vapor release from dental amalgams prepared with binary Hg-in liquid alloys.

For the past ten years, the amounts of mercury vapor released from dental amalgams and the possibility of side-effects caused by these amounts have been discussed. Although no adverse health effects have been substantiated from these minute amounts, besides rare cases of allergies, this release should be reduced. The aim of this study was to reduce the mercury evaporation from a high-copper amalgam during setting by triturating the alloy powder with binary Hg-In liquid alloys having various indium concentrations set at 0, 5, 10, 20, 30, 40, and 50 wt%. Specimens (n = 4) were made for each amalgam according to ANSI/ADA Specification #1 and placed into a measuring chamber kept at 36.5 +/- 0.5 degrees C, through which a continuous air flow of 0.75 L/min was pumped. The total mercury release was measured during the setting period, according to the method described by Ferracane et al. (1992). Four additional specimens were prepared from a modified 14% Indisperse amalgam powder for the purpose of comparison. The results showed that the release of mercury vapor decreased with increasing indium concentrations, and that the amalgams made with the Hg-In liquid alloy with 10% In or more released significantly less mercury than the modified 14% Indisperse. The method of mixing indium in mercury prior to trituration appeared to be another effective method for reducing mercury evaporation during setting. The reduced mercury release may be explained by a reduction of mercury concentration in the structure, a reduction of vapor pressure for the mercury in the matrix phases, or more efficient formation of a surface oxide layer.

Dental Amalgam↗

Effects of insulin on protein kinase-C (PKC) in HIRC-B cells: specific activation of PKC epsilon and its resistance to phorbol ester-induced down-regulation.

We evaluated the role of protein kinase-C (PKC) during insulin action in HIRC-B cells. Insulin provoked rapid increases in 1) diacylglycerol; 2) translocation of PKC epsilon, but not PKC alpha, PKC delta, or PKC zeta, from the cytosol to the membrane fraction; 3) membrane PKC enzyme activity; and 4) phosphorylation of immunoprecipitable 80-kilodalton (kDa) myristylated alanine-rich C-kinase substrate (MARCKS) protein and heat-stable 80-kDa protein (also probably MARCKS). Phorbol esters stimulated the translocation of PKC alpha and PKC delta as well as PKC epsilon, but not PKC zeta. The effects of phorbol esters on 80-kDa MARCKS phosphorylation were approximately 4 times as strong as those of insulin. Treatment of HIRC-B cells with phorbol esters for 20-24 h resulted in complete loss of immunoreactive PKC alpha and PKC delta in cytosol and membrane fractions, but substantial amounts of PKC epsilon were persistently translocated to the membrane fraction of down-regulated cells. This persistently translocated, residual PKC epsilon in down-regulated cells was associated with increased basal hexose uptake, but this was not due to PKC activation, as it was not inhibited by the PKC inhibitor, RO 31-8220. Acute insulin treatment, on the other hand, increased hexose uptake in down-regulated cells, and this insulin-stimulated uptake was inhibited by RO 31-8220 in down-regulated cells as well as in nondown-regulated cells. Insulin also stimulated the phosphorylation of the heat-stable 80-kDa protein in down-regulated cells, suggesting that the residual PKC epsilon in these cells can be activated by insulin.

Animals↗

[The anti-HCV assay in viral hepatitis and hepatoma and the relationship between HCV infection and blood transfusion].

Two hundred cases of various kinds of viral hepatitis and hepatocellular carcinoma were tested for serum anti-HCV. The positive rates of anti-HVC in patients with severe hepatitis and patients with cirrhosis were 42.86% and 46.15%, respectively. They were significantly higher than those in patients with other kinds of hepatitis (P < 0.05). The positive rate of anti-HCV was 67.5% in patients with posttransfusion hepatitis, 20.47% in healthy blood donors. In posttransfusion hepatitis B it was only 2.5%. Our results demonstrated that blood transfusion played an important role in transmitting HCV. Our findings also indicated that dual infection of HBV and HCV was important in the course of chronic hepatitis, cirrhosis and severe hepatitis. 50% of the anti-HCV positive patients with chronic hepatitis had slightly elevated serum alanine aminotransferase level. This showed that liver damage caused by HCV may be a chronic course.

Adult↗

[Studies on morphological superstructure of inactivated rabies virus and uninactivated rabies virus].

Rabies is widely epidemic in human and animals. It is a very dangerous disease at present. In 1919, semple has shown that antigenicity was not destroyed by chemicals. After that inactivated rabies vaccine was widely used in human being up to more than seventy years. But the afferration of morphological superstructure between inactivation and uninactivated, we have not see any report on the world.

Formaldehyde↗

[The mechanism and clinical significance of decreased anion gap in patients with COPD and acid-base imbalance].

The blood-gas and electrolytes of 427 blood samples from patients with COPD and acid-base imbalance were analysed. The results showed that 14 types of acid-base imbalance were present in patients with COPD and the anion gap decreased in 8 types of acid-base imbalance, especially in respiratory acidosis, metabolic alkalosis and coexistence of both. The anion gap in respiratory acidosis and metabolic alkalosis were 0.8 +/- 6.6mmol/L and 2.1 +/- 7.3mmol/L, respectively. The anion gap in respiratory acidosis with metabolic alkalosis was negative. In all patients the HCO3- increased, and the total anion and total cation diminished. The anion gap decreased owing to the diminution of unmeasured anion. Clinically, the criterion for judging metabolic acidosis with increased anion gap is a value of anion gap over 16 mmol/L. But in case respiratory acidosis (or metabolic alkalosis) and metabolic acidosis coexist in a patient, the anion gap for judging metabolic acidosis should be decreased appropriately.

Acid-Base Equilibrium↗

[Evolution of biomechanical changes and microstructural components in autogenous vein grafts].

We evaluated the compliance characteristics of autogenous vein grafts clinically and experimentally. The image analysis instrument was applied in measuring the relative contents of elastin and collagen of the grafts. The results showed the consistent compliance mismatch between the vein graft and the host artery, but no definitive bearing on abnormal blood flow velocity waveform by the compliance mismatch. The compliance characteristics of the vein graft resembled these of the vein rather than those of the artery. The relative contents of elastin and collagen within the graft wall and the ratio of collagen to elastin (C/E) did not change significantly as a function of time. The vein graft and vein had the similar value of C/E, which was lower than that of the artery.

Adolescent↗

Effect of albendazole on the larvae and eggs of Necator americanus in golden hamster.

When golden hamsters infected with adult Necator americanus were treated ig with albendazole(Alb) 75 or 150 mg/kg, the efficacy rates were 83.8% and 100%, respectively. Three days before treatment, the mean numbers of larvae recorded from the incubation of feces from 2 treated groups were 29,716 +/- 3,299 and 28,256 +/- 118 per gram of feces, while in the control group, it was 8,828 +/- 2,659. Within 3 days after treatment, no larva was detected in the 2 treated groups, but in the control group the mean larva number was 9,066 +/- 7,416. Furthermore, in 2 treated groups none or only a few degenerated eggs could be found using saturated saline solution method. when infected golden hamsters were treated ig with Alb at a single dose of 150 or 300 mg/kg on day 3, 7 or 14 after infection with the third stage larvae, the egg positive rates in the feces were 0-9.1%, while the worm reduction rates were 96.8-100%.

Albendazole↗

Effect of albendazole on Ancylostoma caninum larvae migrating in the muscles of mice.

When mice inoculated with 1,000 third-stage larvae of Ancylostoma caninum for 1 week were treated intragastrically (ig) with albendazole (Alb) 75, 150 or 300 mg/kg.d for 3 days, the mean larva numbers collected from the muscles of each group were 2.7 +/- 1.7, 2.0 +/- 1.5 and 1.0 +/- 1.0, respectively, being much less than that 205 +/- 68 of the control group. In mice treated ig with Alb 150 mg/kg.d for 3 days, the concentrations of Alb and its effective metabolite, albendazole sulfoxide (AlbSO), were determined in plasma and the muscles at different intervals after the last medication using high performance liquid chromatography. The results showed that only low concentrations of Alb were detected in both plasma and the muscles. However, higher concentrations of AlbSO were found not only in the plasma (5.4-10.5 micrograms/ml), but also in the muscles (2.2-4.6 micrograms/g). The higher contents of AlbSO in the muscles would be helpful for killing the Ancylostoma larvae migrating in the muscles of mice.

Albendazole↗

Jackknife estimators of variance for parameter estimates from estimating equations with applications to clustered survival data.

An estimate of a parameter vector beta is often obtained by setting a "score" vector equal to zero and solving for beta. Estimating equations of this type include maximum likelihood, quasi-likelihood (McCullagh, 1983, Annals of Statistics 11, 59-67), and generalized estimating equations (Liang and Zeger, 1986, Biometrika 73, 13-22). White (1982, Econometrica 50, 1-26) proposed a variance estimator for beta that is robust to model misspecification. We show that a "one-step" jackknife estimator of variance is asymptotically equivalent to the variance estimator proposed by White. The one-step variance estimator may be preferred when the appropriate computer packages are not available to compute White's estimator directly. This jackknife estimator is very useful in our example with clustered survival data.

Analysis of Variance↗

[7 elements in patients with heart diseases and their relationship with blood pressure and biochemical target].

The trace elements Zn, Cu, Fe, and ordinary elements K, Na, Ca, Mg in serum of 711 patients with heart disease (HD) were determined with GGX-II atomic absorption spectrophotometer and flame photometer. It was found that the contents of K, Ca/Mg in HD were significantly lower than those in the control, while the content of Na, Mg, Zn, Fe, and Zn/Cu, Na/K were significantly higher than those in the control. There was a significantly negative correlation between K, Ca/Mg and blood pressure (BP), between Zn/Cu and HDL-ch, and a significantly positive correlation between Na, Zn, Fe, Zn/Cu, Na/K and BP, between Fe and Hct, between Zn/Cu and Hct, TG, VLDL-ch.

Adult↗

Familial predisposition to precancerous gastric lesions in a high-risk area of China.

Aggregation of intestinal metaplasia and dysplasia was investigated among families participating in a population-based gastroscopic screening survey in an area of China with one of the world's highest rates of stomach cancer. The prevalence of gastric dysplasia was significantly increased among those with dysplasia among siblings or spouses, but not parents. The odds of dysplasia were nearly doubled if an eldest brother or a spouse was affected. Sibling and spousal associations for intestinal metaplasia were much less pronounced and not statistically significant. The specificity of the findings suggests that familial risk of advanced precancerous lesions (dysplasia) is influenced not only by genetic factors, but also by environmental factors operating in childhood and early adult life.

Adult↗

[Clinical effect and experimental study of xijian tongshuan pill].

Xijian Tongshuan pill (XJTS), consisted of Siegesbeckia orientalis, Moschus moschiferus, Hirudo nipponica, Prunus Persicae, Carthamus tinctoruis, Ligusticum wallichi, Panax notoginseng, Angelica Sinensis, Borneolum, etc, were used in treating 70 patients with cerebral thrombosis. The marked effective rate was 82.9%, total effective rate was 96.7%. In control group A, Dextranum and Venoruton were used, in control group B cyclandelate capsule were used. The marked effective rate was 61.7% and 61.1% respectively, the total effective rate was 81.7% and 83.3%. The differences were significant (P < 0.01). The improvement of blood rheology and CT of brain were also significant (P < 0.01). The experiment proved that XJTS pill could inhibit and delay the thrombosis of rabbit, inhibit the platelet aggregation. Acute and subacute toxicity tests proved that XJTS pill was safe and effective.

Adult↗

Effects of insulin and phorbol esters on MARCKS (myristoylated alanine-rich C-kinase substrate) phosphorylation (and other parameters of protein kinase C activation) in rat adipocytes, rat soleus muscle and BC3H-1 myocytes.

To evaluate the question of whether or not insulin activates protein kinase C (PKC), we compared the effects of insulin and phorbol esters on the phosphorylation of the PKC substrate, i.e. myristoylated alanine-rich C-kinase substrate (MARCKS). In rat adipocytes, rat soleus muscle and BC3H-1 myocytes, maximally effective concentrations of insulin and phorbol esters provoked comparable, rapid, 2-fold (on average), non-additive increases in the phosphorylation of immunoprecipitable MARCKS. These effects of insulin and phorbol esters on MARCKS phosphorylation in intact adipocytes and soleus muscles were paralleled by similar increases in the phosphorylation of an exogenous, soluble, 85 kDa PKC substrate (apparently a MARCKS protein) during incubation of post-nuclear membrane fractions in vitro. Increases in the phosphorylation of this 85 kDa PKC substrate in vitro were also observed in assays of both plasma membranes and microsomes obtained from rat adipocytes that had been treated with insulin or phorbol esters. These insulin-induced increases in PKC-dependent phosphorylating activities of adipocyte plasma membrane and microsomes were associated with increases in membrane contents of diacylglycerol, PKC-beta 1 and PKC-beta 2. Our findings suggest that insulin both translocates and activates PKC in rat adipocytes, rat soleus muscles and BC3H-1 myocytes.

Adipocytes↗

Use of site-directed mutagenesis of allele-specific PCR primers to identify the GSTM1 A, GSTM1 B, GSTM1 A,B and GSTM1 null polymorphisms at the glutathione S-transferase, GSTM1 locus.

We describe the identification of the GSTM1 null, GSTM1 A, GSTM1 B and GSTM1 A,B polymorphisms at the glutathione S-transferase GSTM1 locus using a single-step PCR method. Target DNA was amplified using primers to intron 6 and exon 7 with site-directed mutagenesis being used to introduce a restriction site in DNA amplified from GSTM1 *A, thereby allowing differentiation of this allele and GSTM1 *B. The accuracy of this approach in identifying the GSTM1 A, GSTM1 B, GSTM1 A,B and GSTM1 null polymorphisms was confirmed by comparison with, firstly, an established PCR method that distinguishes GSTM1 *0 homozygotes from individuals with the other GSTM1 genotypes and, secondly, GSTM1 phenotypes determined using chromatofocusing.

Alleles↗

Defective stimulation of cyclic AMP by prostaglandin E2 in colonic epithelial cells in colitis.

The present study investigated the effect of vasoactive intestinal peptide and prostaglandin E2 on cyclic adenosine monophosphate levels in isolated colonocytes during experimental colitis. Intra-rectal trinitrobenzenesulfonic acid induced a colitis-like inflammation in the rabbit distal colon. Basal levels of cyclic adenosine monophosphate were similar in control and colitic colonocytes. Levels were increased by prostaglandin E2 and vasoactive intestinal peptide in control cells. Colonocytes from colitic tissue responded to vasoactive intestinal peptide normally, but exhibited an attenuated response to prostaglandin E2. We conclude during colitis the epithelium exhibits a specific alteration in prostaglandin E2 receptor number, affinity or adenylate cyclase coupling.

Animals↗