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Biomedical subjects

M J Wang

Publications and source records attributed to M J Wang.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Diagnosis of subclinical hepatic encephalopathy: a parallel and comparative study between the evoked potentials and the performance psychometric tests].

The authors report the results of a parallel study between the three kinds of evoked potentials (EP) i.e. visual, brainstem auditory and somatosensory evoked potentials (VEP, BAEP and SEP) and psychometric tests in 30 posthepatitic cirrhotic patients. The results were compared with those from 20 peptic ulcer patients in healing stage. Psychometric tests were abnormal in 65.5% of the cirrhotic and in none of the peptic ulcer patients. The three kinds of evoked potentials were abnormal in 58.6% of the cirrhotic patients and in 5% of the peptic ulcer patients. The VEP, BAEP and SEP was abnormal in 13.3%, 10% and 50% of the cirrhotics respectively. The results of this study showed: of the three kinds of evoked potentials, SEP is the most sensitive one. The evoked potentials and the performance psychometric tests are complementary in the diagnosis of subclinical hepatic encephalopathy.

Adult↗
PubMed1992

Augmentation of the systemic host anti-tumor response through laser excision.

This study examines whether primary laser excision results in augmentation of the systemic host anti-tumor response to tumor rechallenge. Single R3230AC mammary tumor implants, (0.5 x 0.5 x 1.0 mm), were grown in 112 female Fisher 344 rats. The animals were randomized. Group S tumors were excised by scalpel. Group E was excised with a Surgistat electrocautery (Valley Labs, Boulder, CO). Group CS was excised with a Sharplan 1100 CO2 laser (Sharplan, Allendale, NJ) at 25 watts (W) continuous wave (CW) (0.2 mm spot size) and the wound was "sterilized" with a 5-mm spot size by gently heating the tissue without blanching. Group K was excised with a KTP/532 laser (Laserscope, San Jose, CA) at 17 W CW using a 400 microns fiber. Group Y was excised with a Sharplan 2100 Nd:YAG laser set at 15W CW using a 0.2 mm clear sapphire tip. A second tumor implant, (0.5 x 0.5 x 1.0 mm), was placed at a remote site 14 days postoperatively. An unoperated control group was implanted. Secondary tumor volumes were measured for 36 days and the mean tumor volumes (MTV) were statistically compared. The MTV in groups CS, K, Y, and E was less than control (P less than 0.01). The MTV in groups CS, K, Y, and E was less than group S, although this was not statistically different. Lasers and cautery appear to increase the host response against subsequent tumor challenge. This study corroborates earlier studies of other modalities. Further studies to determine whether this host sensitization is an immune response and to elucidate the mechanisms of this effect are warranted.

Animals↗
PubMed1992

The effect of Nd:YAG laser-induced hyperthermia on local tumor recurrence in experimental rat mammary tumors.

The influence of Nd:YAG laser hyperthermia (45 degrees C for 20 min) on local tumor recurrence followed by CO 2 laser or scalpel excision was studied on 150 F344 female rats that were implanted with R3230AC mammary tumor in the mammary ridge. The development of local tumor recurrence was observed for 39 days postoperatively. All groups undergoing CO 2 laser excision showed a significant reduction in local tumor recurrence (p less than 0.05) compared with the scalpel technique. Animals that underwent CO 2 laser excision and wound sterilization 48 h following laser hyperthermia demonstrated the lowest recurrence when compared with scalpel excision (p less than 0.01). These results indicate that the local thermal effect achieved by laser hyperthermia or laser sterilization plays an important role in the reduction of local tumor recurrence and augments complete local tumor resection.

Aluminum↗
PubMed1992

Rat liver microsomal and mitochondrial metabolism of primaquine in vitro.

The profiles of major metabolites of primaquine (PQ) produced from liver microsomal (MC) and mitochondrial (MT) metabolism were investigated in vitro by silica gel thin layer and reverse phase high pressure liquid chromatography (HPLC). The results indicated that 5-hydroxy primaquine (5-OH PQ) and carboxyprimaquine (CPQ) were simultaneously produced by either microsomes or pure mitochondria preparations. However, the quantitative study showed that microsomes produced approximately 19 times more 5-OH PQ but only 1/34 of the CPQ by mitochondria.

Animals↗
PubMed1992

[In vitro liver microsomal metabolism of antimalarial primaquine].

The profile of the major metabolites of primaquine produced by in vitro liver microsomal metabolism was investigated with silica gel thin-layer and high performance liquid chromatography (HPLC) analysis. The results indicated that the liver microsomal metabolism could simultaneously produce both 5-OH PQ (quinoline ring oxidation product) and CPQ (side-chain oxidative deamination product). However, the quantitative comparative study of microsomal metabolism showed that the production of 5-OH PQ was far much higher than that of CPQ.

Animals↗
PubMed1992

T lymphocyte changes in open heart surgery.

To investigate the effect of open heart surgery on T lymphocytes and their subpopulations, 20 patients, who had undergone moderate- to high-dose fentanyl anesthesia and a cardiopulmonary bypass (CPB), were studied using flow cytometry techniques and monoclonal antibodies during and after surgery. The ages of these patients ranged from four to 61 years with eight being male and 12 being female. The disease entity consisted of four with coronary, six with congenital and 10 with valvular heart disease. No cyanotic patients were included in this study. Peripheral blood samples were collected before anesthesia, immediately before the surgical incision, on the first postoperative day (POD1) and on the second postoperative day (POD2), respectively. We found no significant changes in the percentage of total T cells (T3), or helper (T4) and suppressor (T8) T cells during anesthesia before the surgical incision. On POD1, all T lymphocyte subset percentages decreased significantly when compared to pre-operative values (total T cells: 58.4 +/- 12.6 vs 24.4 +/- 8.4, helper T cells: 33.3 +/- 10.1 vs 15.4 +/- 6.3, suppressor T cells: 23.0 +/- 6.4 vs 10.0 +/- 4, all p less than 0.001) but returned to preoperative levels on POD2. Throughout the study period, there were no significant changes in the T helper cell to T suppressor cell ratio. In spite of the transient decrease in T lymphocytes and their subpopulations, no clinical evidence of infection was noted in any patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Pharmacokinetics of four benzimidazoles administered intragastrically to mice infected with secondary cysts of Echinococcus granulosus].

Mice infected with secondary cysts of Echinococcus granulosus were treated ig with mebendazole (Meb), albendazole (Alb), albendazole sulfoxide (AlbSO) or albendazole sulphone (AlbSP) at equal effective dosage. The blood concentrations-time courses of the four drugs were adequately fitted to a liner one-compartment open model analysed with a modified NONLIN program, and the major pharmaco- kinetic parameters were then calculated (Table 1). When Alb was given ig to the infected mice, 76.2-84.5% of the drug absorbed was metabolized to AlbSO. There fore, the pharmacokinetics of AlbSO in Alb group was determined. After ig administration of Meb to the infected mice, the ratio of the drug contents in cyst wall to corresponding plasma concentrations of Meb was 10.6-26.9%, but much less in cyst fluid. In Alb and AlbSO groups, similar AlbSO contents in cyst wall and cyst fluid with higher ratio to plasma concentrations were observed (Fig 3). The results suggest that E granulosus cysts were more susceptible to Meb than to Alb or AlbSO, and improvement of Meb absorption would be favourable for enhancement of efficacy in the treatment of hydatid disease.

Albendazole↗
PubMed1990

Substrate masking: binding of RNA by EGTA-inactivated micrococcal nuclease results in artifactual inhibition of RNA processing reactions.

Inhibition of an RNA processing reaction after treatment with the Ca2(+)-dependent micrococcal nuclease (MN) is often used as a criterion for the presence of a required RNA or ribonucleoprotein component in the system. Following MN digestion, the nuclease is inactivated with EGTA and radiolabeled substrate is added to assay for remaining RNA processing activity. We found previously that inhibition of RNA processing by MN need not involve RNA hydrolysis: EGTA-inactivated MN can suppress RNA processing if the assay is performed in the absence of carrier RNA. We now demonstrate both by native gel electrophoresis and by nitrocellulose filter retention that EGTA-inactivated MN forms a complex with free RNA which can be dissociated by addition of synthetic polynucleotides or heparin. In the absence of Ca2+, nuclease binds to precursor tRNA with an apparent KD congruent to 1.4 x 10(-6) M, comparable to its reported affinity for DNA. In an assay for endonucleolytic tRNA maturation, inactivated MN bound to radiolabeled pre-tRNA physically blocks the sites of endonuclease cleavage and prevents tRNA processing. We call this phenomenon 'substrate masking'. Addition of excess carrier RNA competes with pre-tRNA for MN binding and restores normal processing.

Chloroplasts↗
PubMed1990

General anesthesia with propofol (continuous intravenous infusion) supplemented with nitrous oxide: comparison with isoflurane.

Thirty adult surgical patients (ASA I-II) undergoing superficial operations of short duration (about 1h) were arbitrarily divided into two groups. In group A (n = 15), anesthesia was induced with propofol, 2 mg/kg, iv. After endotracheal intubation with the aid of succinylcholine (1 mg/kg, iv), anesthesia was maintained by continuous iv infusion of propofol (0.05-0.2 mg/kg/min) with nitrous oxide and oxygen (2:1). In group B (n = 15), induction and endotracheal intubation were accomplished using thiopental (4 mg/kg, iv) and succinylcholine (1 mg/kg). Anesthesia was maintained with isoflurane (0.5-2.0%), nitrous oxide and oxygen (2:1). Atracurium was used in both groups as muscle relaxant. Hemodynamic responses to laryngoscopy and endotracheal intubation and during operation were not significantly different between the two groups. However, recovery to verbal command and orientation was significantly more rapid in the propofol group (7.8 +/- 4.8 min and 11.2 +/- 5.1 min) than in the isoflurane group (15.6 +/- 4.9 min and 22.6 +/- 6.0 min). In conclusion, continuous propofol infusion combined with nitrous oxide and muscle relaxant is suggested as a better method compared with isoflurane for short operations because of more rapid complete recovery.

Adult↗
PubMed1989

Passive protection of mice, goats, and monkeys against Japanese encephalitis with monoclonal antibodies.

Six monoclonal antibodies (McAbs) against Japanese encephalitis virus (JEV) were tested for passive protection in JEV-infected mice, goats, and rhesus monkeys. mG9 and nG2 had no protective effect; mG3 and 2D2 had some protective effect, but not sufficient to be of therapeutic significance; and 2H4 and 2F2 had excellent protective efficacy in mice even 120 hr after infection when most of the mice in the virus control group were sick. The mixture of 2H4, 2F2, mC3 (M-McAb), and their F(ab')2 fragments showed excellent protection in mice, goats, and monkeys and was safe. The protective effects of McAbs correlated with their neutralization titers, but cytotoxicity-mediated activities also played a role in protection.

Animals↗
PubMed1989

A method of evaluating inspector's performance differences and job requirements.

Large individual differences are among the most consistent findings in the study of industrial inspection. From a statistical point of view, a large proportion of the variation in inspection performance is attributed to this individual factor. Based on the conclusions obtained from the review of previous papers, the relations between subjects' cognitive factors and inspection performance were shown to be in need of further exploration. The objective of this paper is to introduce a method that can explore this large proportion of variation by concentrating on individuals' cognitive attributes and how each contributes to the efficiency and effectiveness of inspection performance. In an experiment, three inspection tasks and 11 cognitive pretests were included. Through factor analysis and Pearson correlations, some significant predictive relationships were found. The findings can be applied to set up selection criteria as well as training schemes for industrial inspectors.

Journal Article↗
PubMed1988

Novel mechanisms for maturation of chloroplast transfer RNA precursors.

Despite the prokaryotic origins of chloroplasts, a plant chloroplast tRNA precursor is processed in a homologous in vitro system by a pathway distinct from that observed in Escherichia coli, but identical to that utilized for maturation of nuclear pre-tRNAs. The mature tRNA 5' terminus is generated by the site-specific endonucleolytic cleavage of an RNase P (or P-type) activity. The 3' end is likewise produced by a single precise endonucleolytic cut at the 3' terminus of the encoded tRNA domain. This is the first complete structural characterization of an organellar tRNA processing system using a homologous substrate. In contrast to eubacterial RNase P, chloroplast RNase P does not appear to contain an RNA subunit. The chloroplast activity bands with bulk protein at 1.28 g/ml in CsCI density gradients, whereas E.coli RNase P bands as ribonucleoprotein at 1.73 g/ml. Chloroplast RNase P activity survives treatment with micrococcal nuclease (MN) at levels 10- to 100-fold higher than those required to totally inactivate the E.coli enzyme. The chloroplast system is sensitive to a suppression of tRNA processing, caused by binding of inactive MN to pre-tRNA substrate, which is readily overcome by addition of carrier RNA to the assay.

Journal Article↗
PubMed1988

Defibrillation current and impedance are determinants of defibrillation energy requirements.

The relationship between various electrical descriptors of shocks for cardiac defibrillation is incompletely understood. Defibrillating energy, current, impedance and pulse duration were measured in 18 dogs. They were subject to repeated fibrillation--defibrillation through epicardial patches, with shocks of preset energy and voltage and variable pulse duration, impedance and peak current. Current and energy requirements for defibrillation were calculated. Energy requirements were positively correlated with pulse duration and interelectrode impedance (r = .70, P less than 0.01). Correcting for heart weight, these correlations were no longer present. However, peak current was correlated with energy requirements both before (r = -0.62, P less than 0.05) and after (r = 0.76, P less than 0.01) correcting for heart weight, with energy requirement decreasing as peak current/g heart increased. Current requirements were significantly less variable between animals than energy requirements (.027 +/- .012 joules/g vs .016 +/- .003 Amps/g), suggesting that current per unit heart weight may be a better descriptor than energy for the ability to defibrillate.

Animals↗
PubMed1985

Dose finding double-blind clinical trial with praziquantel in schistosomiasis japonica patients.

A double-blind clinical trial with praziquantel was carried out. A total of 400 cases was treated with four different dosages, namely, 60, 50, 40 and 30 mg/kg body weight of praziquantel. The drug was given in one day divided into two doses. Identical placebo tablets were used to make up a total of 60 mg/kg. Tolerance was good in all with the exception of one case suffering from asthmatic attack with papule rashes over large area of the body surface. 394 patients were able to be followed up parasitologically six months post-treatment. 79.8%, 71.7%, 78.8% and 70.1% of the patients were negative in the groups with the total dose of 60, 50, 40 and 30 mg/kg respectively. The cure rates as well as the side effects were similar for the four groups. The efficacy was lower than that reported by other authors and the possibility of reinfection was incriminated. In villages with few snails the negative hatching rates in aforementioned four groups were 89.1%, 91.1%, 88.9% and 81.8%, while in villages with abundant snails the rates were 68.2%, 46.5%, 66.7% and 54.8%. The difference between the two areas was statistically significant. Higher efficacy was observed in adults with an average cure rate of 80.0% than in children under 15 years of age, the average cure rate being 57.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗