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Biomedical subjects

L Wong

Publications and source records attributed to L Wong.

At least 199 records · Page 11Linked to original sources
PubMed1989

The expression of T cell receptor-associated proteins during T cell ontogeny in man.

The expression of TCR-associated molecules was examined in human fetal and postnatal tissues. From gestational wk 7 onward in the fetal liver, putative prothymocytes have been identified with cytoplasmic CD3 positivity (cCD3+). These immature cells are TdT- and do not express membrane CD3 (mCD3-) or TCR beta identified by beta F1, but show CD7 and CD45 positivity without CD1, CD2, CD5, CD4, CD8, CD10, and class II Ag. Their high proliferative activity is indicated by greater than 85% Ki67 positivity. After the 10th wk, beta F1+, mCD3+ cells also appear in the liver and these are mostly Ki67- but no TCR gamma delta-bearing cells can be identified at such an early stage of extrathymic development. In the mCD3- TdT-fetal thymus (10 1/2 to 18th wk) cCD3+, mCD3- CD1-blasts proliferate (Ki67+) and lack TCR-beta or TCR-gamma delta. The TdT-, CD1+ cortical thymocytes develop into TCR-beta + and WT31-positive (TCR-alpha beta +) cells. Subsequently TdT-positive thymocytes become detectable around 19 to 20 wk, and in such glands the peak of proliferative activity is seen among TdT+, cCD3+ cells which appear to acquire, in a regular sequence, cytoplasmic beta F1 (TCR-beta), mCD3, and TCR-alpha beta (WT31 positivity) together with the loss of TdT and Ki67 positivity. A newly described transitional population of cells is TdT-, beta F1+ but exhibits no detectable WT31 positivity. These cells correspond to the CD1+, mCD3+ thymocytes and are probably the targets of thymic selection. The cells of the TCR-gamma delta lineage, detected by mAb TCR-delta-1 and delta TCS1, are rare (0.02 to 0.5%) among thymocytes from gestational wk 10 1/2 onward through the whole span of thymic development, but these cells include a proportion (18 to 59%) of cells expressing CD1 Ag, suggesting that these TCR-gamma delta cells differentiate in the thymus. Among the CD1+, TCR-gamma delta + thymocytes, no TdT positivity can be detected.

Adolescent↗
PubMed1989

Contribution of endosomes to intrahepatic distribution of apolipoprotein B and apolipoprotein E.

The endosomal contribution of apolipoprotein B and apolipoprotein E to the intrahepatic distribution of these 2 apolipoproteins was studied. The endosomal contribution of the apolipoproteins was estimated by comparing the specific radioactivities of the injected apolipoproteins with that of apolipoproteins in the liver. The endosomal contribution is further validated by using a least-squares linear combination method that has been described previously (Wong and Pino: European Journal of Biochemistry 164:357-367, 1987). The results using these two independent analyses were similar. There was no difference in endosomal contribution of the apolipoproteins between the fasted and fed rats. In both cases, total endosomal contribution in the microsomal fraction of apolipoprotein B was estimated at 7-10% and that for apolipoprotein E was estimated at 62-66%. The molecular weights of the two apolipoproteins in the endosomes closely resembles those of the injected apolipoproteins in the very low density lipoproteins, indicating little or no apolipoprotein loss during receptor-mediated endocytosis. It is concluded that while there was no substantial contribution of apolipoprotein B to the intrahepatic distribution of that protein, the contribution of extrahepatic apolipoprotein E to intrahepatic apolipoprotein E distribution is substantial.

Animals↗
PubMed1989

A sensitive, inexpensive method for determining minute quantities of lipase activity.

We describe a sensitive and reproducible lipase assay based on the binding of 63Ni to fatty acid. This method can detect down to 1 nmol of fatty acid per milliliter of solution. It has been adapted for measuring low concentrations of lipoprotein lipase and hepatic triacylglycerol lipase. Furthermore, in the presence of tritiated triolein, the method is insensitive to radiolabel interference, even when the fatty acid is labeled.

Fatty Acids↗
PubMed1989

Hygiene aspects of occupational exposure to waste anaesthetic gases in Ontario hospitals.

Exposure of workers to waste anaesthetic gases in the operating and recovery rooms of hospitals is an ongoing concern because a number of epidemiological and mortality studies have reported significant adverse effects. To evaluate the health risks if any, and to assist in the development of guidelines or regulations for the hospital sector in Ontario, the Health and Safety Support Services Branch of the Ontario Ministry of Labour conducted this extensive study. The results of the hygiene study show that exposure to waste anaesthetic occurs because of leaks in the anesthetic equipment. The three major sources of leaks (i.e. exhalation valves, masks and high-pressure fittings) produced concentrations above the limit of detection of nitrous oxide (1000 ppm of N2O) in a significant number of samples. Of the samples taken at leak sources those taken at the exhalation valve had the highest percentage of samples above 1000 ppm, which suggested that scavenging systems were not receiving proper service and maintenance. Only 23% of the operating rooms surveyed met the Ontario Ministry of Health Criterion of 24 air changes per hour. Dilution ventilation was less effective than scavenging in keeping down concentrations of air contaminants. The sampling data show that the anaesthetists have the highest time-weighted average exposure (median value range 56-79 ppm) of the major group of occupations surveyed and that the general surgeons' TWA is much lower (28 ppm). It was concluded that the dilution ventilation rate of 24 air changes per hour should be maintained in all operating rooms and that there should be no recirculation of exhaust air when operations are in progress. To keep down concentrations of anaesthetic gases scavenging systems should be provided in all operating rooms. In each hospital maintenance should be the responsibility of a qualified staff member who has been adequately trained in the repair and maintenance of anaesthetic delivery systems. Finally, a qualified staff member should be responsible for conducting periodic personal monitoring in operating rooms (ORs) and recovery rooms (RRs) and the sampling strategy should include individuals and the exhaust grilles.

Air Pollutants, Occupational↗
PubMed1989

CD2 expression and function in lepromatous leprosy.

Leprosy is a spectral disease in which clinical presentation is thought to be related to the host immune response. Previous investigations have suggested that selective unresponsiveness to Mycobacterium leprae in patients with lepromatous leprosy is due to the presence of M. leprae-specific T-suppressor cells. However, it has recently been suggested that CD2 modulation was the mechanism for the observed impaired immune response in lepromatous patients. Therefore, we studied the expression of CD2 and CD3 on lymphocytes in lepromatous skin lesions and peripheral blood mononuclear cells (PBMC). Using immunohistochemical techniques, we found that virtually all of the CD3+ cells in leprosy skin lesions expressed CD2. In addition, indirect immunofluorescence flow cytometry demonstrated that most CD3+ cells in the peripheral blood possessed the CD2 marker, suggesting that CD2 expression of T-lymphocytes is normal. T-cell activation using paired anti-T11(2) and anti-T11(3) or anti-CD3 monoclonal antibodies demonstrated similar 3H-thymidine incorporation and gamma interferon production in the PBMC of lepromatous patients in comparison with the PBMC of their contacts and tuberculoid patients. However, lepromatous PBMC did not proliferate or produce gamma interferon in response to M. leprae. Our data suggest not only that CD2 expression is normal on T lymphocytes in lepromatous leprosy skin lesions but also that CD2 expression in peripheral blood lymphocytes is functional in T-cell activation. Defective CD2 modulation does not appear to be the mechanism for specific unresponsiveness in lepromatous leprosy.

Antibodies, Monoclonal↗
PubMed1989

The preterm rat: a model for studies of acute and chronic neonatal lung disease.

A preterm rat model has been developed for studies of acute and chronic neonatal lung disease. Premature delivery 24 h before the normal time of delivery is associated with immature pulmonary phospholipid and antioxidant enzyme profiles. The premature lung is more fragile and ruptures at a lower lung vol (172 +/- 8 microL) than the full-term fetal lung (259 +/- 14 microL). Only 7% of premature lungs will float in liquid, after inflation to 85% of the rupture vol, compared with 87% of term fetal lungs. This lung immaturity was reflected in a survival rate of only 6% by 36 h after delivery if the preterm pups were placed in air, which increased to 47% when they were placed in greater than 95% oxygen. Though greater than 95% oxygen enhanced survival of preterm pups during the 1st wk of life, these survivors had a 50% mortality during the 2nd wk of exposure to greater than 95% oxygen. The preterm pup will tolerate intraperitoneal injection of antioxidant enzymes entrapped in liposomes and has a better retention of these liposomes in the lung compared with the term pup. We conclude that the preterm rat is a suitable model for studies of acute and chronic neonatal lung disease.

Acute Disease↗
PubMed1989

Evidence of viral replication in HBsAg positive patients with hepatocellular carcinoma: measurement of serum hepatitis B virus deoxyribonucleic acid (HBV-DNA).

Sera from 60 consecutive patients with hepatocellular carcinoma (HCC) diagnosed by either a positive histology or at least two of the following: CT scan, hepatic ultrasound, hepatic angiogram and raised alpha-foetoprotein levels, were studied to determine their Hepatitis B surface antigen (HBsAg) status and the frequency of continuing viral replication. Markers of Hepatitis B virus (HBV) infection were detected using enzyme and radioimmunoassays. Hepatitis B DNA (HBV-DNA) was measured by molecular hybridization using a labelled recombinant HBV-DNA probe. Sera from 30 HBsAg positive 'healthy' carriers were used as controls. Forty-seven (78%) patients were HBsAg positive. Evidence of previous HBV infection was present in 12 of 13 HBsAg negative patients. 30% of HBsAg positive patients were HBeAg positive, 62% were anti-HBe positive and 8% had no 'e' markers. Serum HBV-DNA was present in 21 (45%) HBsAg positive patients: 10 (71%) HBeAg positive patients, 10 (35%) anti-HBe positive patients and 1 (25%) patient without any 'e' markers. Serum HBV-DNA levels were less than 0.6 ng/ml in 16 (76%) patients. HBV-DNA was absent in all HCC patients who were HBsAg negative. The frequency of serum HBV-DNA positivity was higher in 30 patients with HCC when compared with 30 age and sex matched healthy HBsAg positive individuals (57% vs 13% p less than 0.01). A sizeable proportion of HBsAg positive HCC patients have on-going viral replication and this is present in patients who were thought to have stopped replicating (anti-HBe positive patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Effect of total parenteral nutrition on hepatic histology.

We evaluated the effect of total parenteral nutrition (TPN) on abnormalities of hepatic histology. Liver biopsies of 93 patients who were concurrently receiving TPN were compared with a control group of 35 patients. The control patients were matched for extent of preexisting liver disease and degree of illness. The liver biopsy specimens were blindly graded on 19 histopathologic findings, including fatty change, portal inflammation, and cholestasis. Twenty-seven clinical variables, such as preexisting liver disease, the presence or absence of sepsis or shock, and number of days receiving TPN before biopsy, were recorded. Individual and partial correlations were established between the clinical variables and histopathologic findings. The control and TPN groups proved to have been closely matched regarding the extent of risk factors for hepatic histopathologic features. Positive correlations were repeatedly found between abnormal hepatic histologic features and preexisting liver disease, abdominal sepsis, renal failure, and blood transfusion but not with the administration of TPN. We conclude that clinical phenomena, such as existing liver disease, renal failure, and abdominal sepsis, rather than administration of TPN, had a predominant effect on histopathologic features in this group of patients.

Humans↗
PubMed1988

Lactate dehydrogenase activity in cultured neonatal rat heart cells exposed to doxorubicin.

Doxorubicin (Adriamycin, ADR) is an anthracycline antineoplastic with the serious side effect of dose-related cardiomyopathy. A model of ADR cardiotoxicity was created to examine some subcellular toxic effects of ADR with cultured cardiac myocytes (CMCs) exposed to 1 x 10(-7) to 1 x 10(-5) M ADR for 24 to 48 hr. Lactate dehydrogenase (LDH) activity was monitored in the CMC medium to monitor CMC damage as a function of ADR concentration. A four- to eightfold elevation of LDH activity in medium of CMCs exposed to 1 x 10(-6) to 1 x 10(-5) M ADR was found. No change in LDH activity was detected in medium of CMCs exposed to 1 x 10(-7) M ADR or in control CMCs after 24 or 48 h ADR exposure. Data suggest a dose-dependent effect of ADR on LDH activity in CMC medium. Serial monitoring of LDH in media of ADR-exposed CMCs may correlate with other evidence of ADR cardiotoxicity in vitro.

Animals↗
PubMed1988

Breath hydrogen testing in bacterial overgrowth of the small intestine.

The indirect, noninvasive technique of breath hydrogen (H2) analysis was evaluated in 45 patients suspected of having bacterial overgrowth of the small intestine. Bacterial overgrowth, defined as a jejunal culture yielding at least 10(5) organisms/ml, was present in 27 patients. After dietary preparation and a 12-h fast, subjects received in random order and on separate days 50 g of glucose or 50 g of rice flour in the form of two pancakes. Normal values were established in 20 healthy controls. Twelve of 27 patients with proven bacterial overgrowth had an elevated (greater than 15 ppm) fasting breath H2 level on at least 1 test day. Fifteen of 18 patients with negative cultures had low fasting breath H2 levels. Based on values in controls, a positive breath test was defined as an increase in breath H2 of greater than or equal to 12 ppm after glucose or greater than or equal to 14 ppm after rice flour. A 2-h glucose breath H2 test had a sensitivity of 93% and a specificity of 78% in the diagnosis of overgrowth. The predictive value of a positive test was 86% and that of a negative test was 88%. The combination of both a high fasting breath H2 level and a diagnostic rise of breath H2 after glucose was present in 41% of patients with overgrowth and in none of the patients without overgrowth. Extending the test to 4 h did not increase sensitivity, but decreased specificity. Rice flour was a less satisfactory substrate in predicting the presence of bacterial overgrowth. In conclusion, a high fasting breath H2 level after dietary preparation suggests bacterial overgrowth but lacks sensitivity. The finding of a rise in breath H2 of at least 12 ppm within 2 h of a 50-g glucose challenge is a simple screen for bacterial overgrowth. The combined criteria of a high fasting breath H2 level and a significant rise after glucose are specific for bacterial overgrowth.

Adult↗
PubMed1988

Selective messenger RNA reduction in Alzheimer's disease.

The relative abundance of 7 messenger RNAs extracted from Alzheimer and control neocortex were examined by Northern and quantitative dot blot analysis. The average yield of mRNA coding for NF-L, the 68-kDa moiety of neurofilament protein, was reduced to 27% of control when expressed as the percentage of total RNA or 14% when expressed per gram of neocortex. In contrast, the yields of 6 other messenger RNAs fell into two categories: those which were statistically significantly reduced to about 65% of control and those which were not reduced when expressed as percentage of total RNA. The anomalous low abundance of neuron specific NF-L mRNA, coding for the lowest molecular weight moiety of neurofilament proteins, in cerebral cortex of Alzheimer's disease cannot be adequately accounted for by a non-specific effect of brain damage, neuron cell loss or neurons with neurofibrillary degeneration. We speculate that this mRNA decrease is related to a functional deficit of gene expression in Alzheimer's disease, perhaps related to the non-random increase in chromatin compaction previously reported from this laboratory. The inability of neurons to maintain homeostatic amounts of NF-L transcription products may be linked to the accumulation of abnormal filamentous components characteristically associated with the diseased cytoskeleton.

Adult↗
PubMed1988

Transformations of maps to investigate clusters of disease.

An approach is presented to display and analyze epidemiologic data using population density equalized maps (cartograms). The algorithm for generating these maps is discussed. A specific method for statistically analyzing plotted data is given, followed by an application of maps and analysis to 73 sets of age-, race-, sex-, and site-specific cancer incidence data. The data were obtained from the Surveillance, Epidemiology and End Results project for San Francisco City/County (1978-1981) and combined with 1980 U.S. Census data.

Adult↗
PubMed1988

The role of IVP in blunt trauma.

To investigate the role of the IVP, we studied 139 patients with blunt abdominal trauma and hematuria. Multivariate analysis of clinical parameters was utilized in attempt to predict which patients would have abnormal IVP's and which would eventually require genitourinary operation. Thirty-four patients (25%) demonstrated abnormalities on IVP; however, no combination of clinical findings (including degree of hematuria) could reliably predict which patients would have abnormal IVP's. On the other hand, in 90% of the patients, the necessity for genitourinary operation could be reliably predicted based on: presence of blood at the urethral meatus, degree of hematuria, patient age, Injury Severity Score, and number of rib fractures. We conclude that to detect IVP abnormalities, IVP's need to be performed on all blunt trauma patients with hematuria. However, patients likely to have injuries requiring operative repair can be predicted. Those patients unlikely to have genitourinary injury requiring repair, therefore, may have IVP performed on a nonurgent basis.

Abdominal Injuries↗
PubMed1988

Visual acuity changes with age: some new perspectives.

Snellen chart visual acuity is thought to change very little up to age 60 years. However, any changes in contrast in the retinal and/or neural image with age may only be detected in low contrast and low luminance testing conditions. Only under these conditions does contrast significantly influence visual acuity measurements. In this pilot experiment we show that low contrast visual acuity is considerably worse (two lines of Snellen acuity) for an older group (N = 8, mean age 57) than for a younger group (N = 9, mean age 24.6) in spite of the fact that each subject was referred to the study with 6/6 (20/20) or better acuity. At conventional contrast and luminance levels there is no significant difference between the two groups. The results also suggest that a simple measurement of contrast sensitivity for a small spot of light may allow a contrast correction factor to account for both age and luminance level differences in the contrast vs. acuity function.

Adult↗
PubMed1988

Stress fractures of the tarsal navicular in long-distance runners.

The authors report on a study that attempted to (1) determine anatomic variations that predispose runners to tarsal navicular stress fractures; (2) study that loading responses of runners with stress fractures and of uninjured runners; (3) study the mechanical factors and biomechanics of the foot during running; (4) define a population at risk for developing stress fractures; and (5) propose an alteration in footwear that may reduce the force across the talonavicular joint.

Adolescent↗
PubMed1987

Gradient acrylamide/agarose gels for electrophoretic separation of intact human very low density lipoproteins, intermediate density lipoproteins, lipoprotein a, and low density lipoproteins.

An exponential gradient gel with 0-10% acrylamide and 0.5% agarose was developed for electrophoresis of intact high molecular weight lipoproteins. This system resolves very low density lipoproteins, intermediate density lipoproteins, lipoprotein a, and low density lipoproteins in a size-dependent fashion. The characteristic relative mobility of these species can be determined in relation to protein and colloidal gold reference materials. Electron microscopy of selected lipoprotein fractions confirmed that relative mobility was related to apparent lipoprotein diameter. The composite gel medium can be used with prestained lipoproteins and permits immunoelectroblotting for qualitative analysis of apolipoprotein constituents.

Electrochemistry↗