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Biomedical subjects

L Wong

Publications and source records attributed to L Wong.

280 records · Page 16Linked to original sources
PubMedDate not supplied

Radiolabelled unprocessed bran: validation of a practical labelling technique and evaluation of gastrointestinal transit profiles in health.

Using a radiolabelled bran preparation, a large field of view gamma-camera and a computer, a method has been developed to define and analyse the gastrointestinal transit profile of solids. Unprocessed bran, labelled with technetium (99mTc) sulphur colloid is incorporated into biscuits cooked in a microwave oven. With this preparation, less than 3.4% of the isotope dissociated from the bran in a gastric milieu, and more than 90% of recovered radionuclide activity, were retained with the solid phase during small intestinal transit in subjects with stable ileostomy function. A normal range for gastric emptying (GE), small intestinal transit (IT) and colonic filling (CF) was established in 15 healthy volunteers. Anterior and posterior images were taken until all isotope was present in the colon. Using regions of interest for the stomach and colon, decay corrected geometric mean curves for GE and CF were generated. GE was characterized by a lag phase followed by a linear emptying phase. The GE profile (mean and standard deviation) was described by 'power exponential' parameters of half-emptying time (1.6 +/- 0.4 h) and beta (1.5 +/- 0.2). The IT time was 3.9 +/- 1.5 h. The onset of CF was determined visually (4.1 +/- 1.5 h), and the time of 50% CF filling was determined from the colonic filling curve (5.5 +/- 1.4 h). This technique should provide a useful, practical, clinical and research test to study the pathophysiology and pharmacology of intestinal motor disorders.

Adult↗
PubMedDate not supplied

Combined adjuvant cisplatin and ifosfamide chemotherapy and radiotherapy for malignant mixed müllerian tumors of the uterus.

The role of adjuvant therapy for malignant mixed müllerian tumors of the uterus has not been established. Our aim was to review our experience with sequential adjuvant therapy using cisplatin and ifosfamide chemotherapy and radiotherapy after surgical staging. A retrospective study of 43 patients from 1995 to 2004 was undertaken. Survival was calculated using the Kaplan-Meier method and compared by the log-rank test. The Cox proportional hazard regression model was used to assess the effect of treatment on survival after adjustment for age and stage. Twenty-eight patients received adjuvant chemotherapy and 28 patients had adjuvant radiotherapy. Twenty-one patients underwent sequential adjuvant chemotherapy and radiotherapy. Tumor recurrence occurred in 14 patients at a median duration of 10 months. The overall 2- and 5-year survival was 64% and 60%, respectively. The 2- and 5-year survival for stage I and II diseases was both 95%, while the 2-year survival for stage III and IV diseases was 25%. Patients who underwent sequential adjuvant therapy had an improved survival compared with patients who did not follow the protocol (P= 0.024). Our results with sequential adjuvant therapy are encouraging and justify future randomized trials.

Adult↗
PubMedDate not supplied

The effect of sucrose application frequency and basal nutrient conditions on the calcium and phosphate content of experimental dental plaque.

A reduced pool of calcium in dental plaque would be expected to increase the ability of plaque fluid to dissolve the underlying enamel when the pH falls during sugar exposure. We have examined the relationship between frequency of sugar application and Ca and P(i) concentrations in artificial mouth plaque microcosm biofilms. Ten plaques were grown simultaneously from a human saliva inoculum using a continuous flow of simulated saliva, DMM, supplemented with either urea or glucose to modulate the resting pH. In addition the plaques received sucrose applications of varying frequency: 12-, 8-, 6-, or 4-hourly, or not at all. After 15 days the plaques were sampled by taking 4 full-thickness specimens of each, and acid-extractable Ca and P(i), and alkali-soluble protein and carbohydrate were determined. Ca and P(i) concentrations were in a range comparable with those in human plaque, except in the DMM + urea plaque receiving no sucrose, when concentrations were higher. Plaque Ca concentration decreased significantly as sucrose application frequency increased. Increasing sucrose application frequency also reduced the protein, i.e. the cell biomass, content of the plaques and, in the case of DMM + urea plaques, increased the water-insoluble hexose content, presumably extracellular polysaccharide. Reduced biomass was partly due to the bulking of plaque with extracellular polysaccharide, but the marked effect of urea on polysaccharide formation is not understood. This study shows that increasing frequency of sugar application alters dental plaque by reducing its mineral protection capacity.

Analysis of Variance↗
PubMedDate not supplied

Lipoprotein lipase and hepatic triacylglycerol lipase activities in peripheral and skeletal muscle lymph.

We studied the interstitial fluid concentration of two lipid-metabolizing enzymes (lipoprotein lipase and hepatic triacylglycerol lipase) to determine their importance in interstitial modification of filtered lipoproteins. Despite the use of a very sensitive lipase assay (1 nmol of fatty acid release/ml/hr), lipase activities in plasma and in peripheral and skeletal muscle lymph from control dogs were below the sensitivity of our assay. After heparin injection, hepatic triacylglycerol lipase and lipoprotein lipase activities in plasma were similar. However, the postheparin hepatic triacylglycerol lipase activities in peripheral and skeletal muscle lymph were only 1.4% and 1.1%, respectively, those of plasma. This concentration is considerably less than the lymph concentration of albumin, which has a similar size to the lipases but has a lymph concentration of 30% to 40% of plasma. Lipoprotein lipase activity in peripheral lymph and skeletal muscle lymph was 2.7% and 4.8%, respectively, of plasma activity. Since lipoprotein lipase has a similar size as hepatic triacylglycerol lipase, the disproportionate amount of lipoprotein lipase in lymph as compared to hepatic triacylglycerol lipase could be due to heparin crossing the capillary endothelium and displacing lipoprotein lipase from peripheral cells. Injection of radioactive heparin confirmed that it does cross into the interstitial space in sufficient concentrations to displace lipase from peripheral cells. We conclude that most of the lipase found in lymph after heparin injection is derived from peripheral cells and not from plasma. Furthermore, hepatic triacylglycerol lipase does not play a role in high density lipoprotein remodeling in interstitial fluid. Therefore, it seems likely that the considerable remodeling of high density lipoprotein that we found previously results from its interaction with peripheral cells.

Animals↗
PubMedDate not supplied

Burns and associated nonthermal trauma: an analysis of management, outcome, and relation to the Injury Severity Score.

Nonthermal trauma in patients with burns necessitates additional considerations in management. The charts of all patients with nonthermal trauma admitted to a regional burn center from 1977 to 1987 were reviewed. The causative events and types of injury were determined. The most common injuries were fractures caused by jumping from burning buildings. Fracture management varied, and the only complications that occurred among the 15 of 61 patients with fractures were associated with overlying burns. The mortality rate was 20%, which is comparable to that predicted from the patients' ages and the percent of total body surface area burned. The mortality rate predicted from the Injury Severity Score is much lower, which brings into question its use for analysis of this patient population.

Adult↗
PubMedDate not supplied

Toxicity of phencyclidine and ethanol in combination.

The role of ethanol in phencyclidine-related death and loss of motor co-ordination was studied in male ICR albino mice. LD50s, and ED50s for loss of righting reflex, and for the "rotarod" test were determined for each drug in the presence of various doses of the other. Isobolograms (plots of equieffective dose combinations) of these LD50s and ED50s showed that low doses of ethanol reduced the LD50 of phencyclidine (PCP) by about 20%, while higher doses (1-3 g/kg) of ethanol were without further effect. In contrast to effects on lethality, there was synergism (potentiation) of loss of motor co-ordination. Doses of ethanol above 1 g/kg reduced the ED50 of PCP for loss of righting from about 60 mg/kg to 1-3 mg/kg. Similarly, low doses of PCP (less than 40 mg/kg) reduced the ED50 of ethanol from 3 g/kg to 1 g/kg. There was a slight but consistent synergism between the drugs in the rotarod test over the range of effective doses (0.25-2.0mg/kg PCP and 0.1-1.2 g/kg ethanol). It is concluded that consumption of ethanol does not greatly increase the risk of death from PCP overdose; however the severe adverse effects on motor co-ordination of moderate doses of PCP together with moderate doses of ethanol are greatly potentiated by doses of the other drug. It is estimated that commonly used doses could result in total loss of motor ability, which could explain the prevalence of accidental deaths (especially drowning) when PCP and ethanol have been consumed together.

Animals↗
PubMedDate not supplied

Occupational exposure to Mycobacterium bovis infection in deer and elk in Ontario.

In late 1991, two herds of deer and elk were depopulated at a slaughtering plant in Ontario, followed by processing of infected animals at a rendering plant. We conducted a questionnaire plus tuberculin skin-test survey of 104 exposed slaughtering and rendering plant workers, and government veterinarians and inspectors. Overall, 17 participants were skin-test positive, one of 51 initially skin-test negative subjects tested a second time three months later became positive, consistent with the risk associated with occupational exposure during the depopulation of tuberculous elk previously observed in Alberta. Deer farming is widespread, with 263 herds in Ontario. The likely route of transmission is through aerosols. Possible reasons for the low conversion rate include the use of respiratory protection, absence of a tanning plant, an enclosed rendering plant process, and late skin testing which may have underestimated the number of conversions. Recommendations for prevention are summarized; in particular, respiratory protection for work with infected herds should probably include high efficiency particulate face masks.

Abattoirs↗