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Biomedical subjects

S K Lo

Publications and source records attributed to S K Lo.

At least 109 records · Page 6Linked to original sources
PubMed1994

Cognitive dysfunction in early onset parkinsonism.

Cognitive functions of 24 patients with early onset parkinsonism (age of onset before 40 years) and 24 controls were investigated by a battery of neuropsychological tests. Patients were shown to be impaired in performance IQ (PIQ), conceptual ability and regulation behavior, memory, visuospatial perception, and manual dexterity. Patients were also shown to have a higher Zung Depression score. However, analysis of the testing scores appeared to indicate that only a small portion of poor performance on neuropsychological tests are depression related. The results demonstrated that patients with early onset parkinsonism, in whom the factor of aging is not as important, still show cognitive dysfunction and suggested that Parkinson's disease itself can cause cognitive impairment.

Adult↗
PubMed1993

Congenital infection by human cytomegalovirus with a 65bp deletion in the morphological transforming region II.

Human cytomegalovirus (HCMV) infection is an important cause of neonatal death. Using primers derived from sequences within the morphological transforming region II (mtrII), HCMV DNA was amplified by polymerase chain reaction (PCR) from fixed tissues of infants who had died of congenital HCMV infection. In one neonate, HCMV DNA with reduction in the expected size was detected in the liver, spleen, kidney, adrenal, und thyroid tissues by gel electrophoresis. Nucleotide sequencing of the PCR product revealed a 65bp frame-shift deletion within the 79 amino acid open reading frame (ORF) of the mtrII. Based upon this observation, it is likely that viral genomic rearrangement involving the mtrII may occur in some cases of congenital HCMV infection.

Base Sequence↗
PubMed1993

DNA flow cytometric study of thymic epithelial tumors with evaluation of its usefulness in the pathologic classification.

A DNA flow cytometric study was performed on 64 thymic epithelial tumors using the modified Hedley method with formalin-fixed, paraffin-embedded tissues to evaluate whether ploidy analysis can be a useful aid in differentiating invasive thymoma (IT) from non-invasive thymoma (NT) and in understanding the ploidy pattern of various histologic types of thymic carcinomas (TCs). The IT group was further subdivided into macroinvasive thymoma (macro-IT) and microinvasive thymoma (micro-IT). Six cases were excluded due to a coefficient of variation greater than 6. Aneuploidy with a DNA index greater than 1.05 was found in every group: two of 16 NTs, two of nine micro-ITs, 11 of 13 macro-ITs, and 12 of 20 TCs were aneuploid. However, the proportions of aneuploidy of macro-IT and TC were statistically significantly higher than those of NT and micro-IT (P < .001). Similarly, the DNA indexes of macro-IT and TC were significantly higher than those of NT and micro-IT (P < .004). Therefore, micro-ITs were cytometrically similar to NTs and could be grouped with the NTs. Although ploidy analysis cannot predict whether an individual thymoma is invasive, aneuploidy and a high DNA index would favor a macro-IT, which also has a significantly higher S-phase fraction. Thymic carcinoma and IT cannot be differentiated by DNA flow cytometry. No definite ploidy pattern was observed for various histologic types of TC, but transition from diploid to aneuploid was demonstrated in thymomas undergoing malignant transformation into TC.

Aneuploidy↗
PubMed1993

Thymoma: a study of the pathologic classification of 71 cases with evaluation of the Muller-Hermelink system.

A pathologic study of 71 consecutive cases of thymoma was conducted to determine the value of histologic classification for predicting the invasive potential of thymomas. The traditional and newly proposed Muller-Hermelink classification systems were studied for correlation with thymomas of the three clinicopathologic stages identified as noninvasive thymoma, microinvasive thymoma, and macroinvasive thymoma. None of the histologic types classified by the traditional system were correlated specifically with invasive growth. In contrast, the cortical-type thymoma of the Muller-Hermelink system correlated strongly with both microinvasive thymoma and macroinvasive thymoma (P < .001 for both). Although not all cortical thymomas manifested invasive growth and not all invasive thymomas were of the cortical type, the statistical data suggested that cortical thymomas should be regarded as potentially malignant tumors with the propensity for invasive growth. Spindle-cell thymoma of the traditional system or medullary thymoma of the Muller-Hermelink system, on the other hand, was not associated with invasiveness and behaved as a benign tumor. All other thymomas that were not purely spindle cell or medullary cell in nature had a potential for invasion and aggressive behavior, and this potential seemed to be inversely proportional to the percentage of fusiform cells in such neoplasms. Nevertheless, the results of this study support the usefulness of the Muller-Hermelink classification system in predicting the aggressive potential of thymomas. A group of microinvasive thymomas was identified as a separate group for analysis in this study. Although no recurrences were observed during the follow-up period, microinvasive thymomas deserve further study as a separate group because they correlated strongly with cortical thymoma. The association of thymoma with myasthenia gravis was rather high (63.4%) in this study. Both the mixed-type thymoma of the traditional classification system and the cortical-type thymoma of the Muller-Hermelink system showed statistically significant correlation with myasthenia gravis (P = .002 and .001, respectively).

Adult↗
PubMed1993

Antineutrophil antibody: a test for autoimmune primary sclerosing cholangitis in childhood?

The detection of an antineutrophil antibody which is highly sensitive and specific for adult primary sclerosing cholangitis using indirect immunoalkaline phosphatase has been previously described. In this study, the diagnostic potential of this method in childhood primary sclerosing cholangitis is described. A range of 72 blinded children's sera (36 boys), aged six months to 21 years (10 primary sclerosing cholangitis, eight autoimmune chronic active hepatitis, 10 alpha-1 antitrypsin deficiency, 12 extrahepatic bile duct atresia, 11 ulcerative colitis and 21 normal subjects) was assayed. Eight of the 10 primary sclerosing cholangitis patients were correctly identified. Three patients with chronic active hepatitis also showed the characteristic primary sclerosing cholangitis pattern of staining. No ulcerative colitis patients or any other patients showed this pattern of staining. All normal subjects were negative. As in adult primary sclerosing cholangitis, there is a specific antineutrophil antibody in childhood primary sclerosing cholangitis and this provides further evidence towards an autoimmune aetiology of this condition. The test may have diagnostic potential.

Adolescent↗
PubMed1993

Tissue distribution of autoantigen specific for primary sclerosing cholangitis.

AIM: To investigate the tissue distribution of the autoantigen specific for primary sclerosing cholangitis. METHODS: A range of normal frozen tissues including nervous system, muscle, uterus, ovary, prostate, pancreas, thyroid, salivary gland, adrenal gland, colon, gall bladder, stomach, jejunum, aorta, skin, kidney, liver, spleen and thymus was sectioned, fixed with acetone, and air-dried. Normal bone marrow and HL60, K562, and U937 cells were cytocentrifuged on to slides, air-dried, and alcohol fixed. Four sera from primary sclerosing cholangitis with high titre antibody (> 1/100) were used to screen the tissues using either two-step or APAAP immunohistochemistry. Normal sera were used as controls. RESULTS: Positive signal was detected in neutrophils in spleen with three out of four primary sclerosing cholangitis sera while one out of four primary sclerosing cholangitis sera stained spindle cells in the liver. All four sera stained mature neutrophils of the normal bone marrow. Some bone marrow neutrophil precursors (metamyelocytes and myelocytes) were also positive. All other tissues, including HL60, K562, and U937 cells, were negative. Normal sera were negative on all tissues. CONCLUSION: Antigen specific for primary sclerosing cholangitis seems to be unique to neutrophil polymorphs and is present only after myeloblast differentiation of the myeloid cell line. The antigen may be within the secondary granule of the neutrophil polymorph.

Adult↗
PubMed1993

Positive bowel contrast agent for MR imaging of the abdomen: phase II and III clinical trials.

PURPOSE: To evaluate the efficacy and safety of two dose levels of an orally administered ferric ammonium citrate-based contrast agent for bowel enhancement on T1-weighted spin-echo magnetic resonance (MR) images in 222 patients with known or suspected abnormality of the upper abdomen. MATERIALS AND METHODS: Adverse reactions were graded for intensity, frequency, duration, and relationship to the contrast agent. Twelve unblinded readers compared enhanced with unenhanced images; all MR images were evaluated by two independent offsite radiologists in a blinded review. RESULTS: No statistically significant changes in mean vital signs or laboratory values were seen. Forty-eight of 220 patients (22%) reported minor side effects. The readers found increased intraluminal signal intensity and improved contrast enhancement of the gastrointestinal tract and distention and improved signal homogeneity in 101-107 cases (89%-98%) after ingestion; the blinded reviewers' findings were similar. CONCLUSION: The contrast agent provided new or additional radiologic information in 142 patients (64%), specific additional information in a detected abnormality in 46 of 142 patients (32%), and information that changed diagnosis, management, or surgical approach in 22 of 142 patients (15%).

Abdomen↗
PubMed1993

Hydrogen peroxide-induced increase in endothelial adhesiveness is dependent on ICAM-1 activation.

Reactive oxygen radicals (ROS) generated by phagocytes promote human polymorphonuclear leukocyte (PMN) adhesion to human umbilical vein endothelial cells (EC). We determined the effects of hydrogen peroxide (H2O2), a phagocyte-derived ROS, on EC adhesiveness by determining steady-state intracellular adhesion molecule 1 (ICAM-1) mRNA and ICAM-1 protein expression. The adhesion of PMN to H2O2-treated EC was concentration dependent with maximal adhesion achieved at 0.1 mM H2O2. PMN adhesion occurred rapidly, reaching its maximum value within a 1-h treatment time. The PMN adhesion was dependent on the interaction between CD11/CD18 integrins on PMN and ICAM-1 on EC, since either anti-CD18 or anti-ICAM-1 monoclonal antibodies (MAbs) inhibited (by > 90%) the adhesive interaction between PMN and EC. In parallel with the increases in EC adhesivity, we detected a two- to threefold increase in EC surface expression of ICAM-1 between 0.5 and 1 h after H2O2 challenge. Northern analysis revealed an increase in the steady-state ICAM-1 mRNA signal within 0.5 h after H2O2 exposure, and the response was sustained up to 2 h. Inhibition of intracellular catalase in H2O2-treated EC by 3-amino-1,2,3-triazole augmented the PMN adhesion by 20%, whereas enhancement of EC H2O2-scavenging activity by addition of catalase abrogated the H2O2-induced PMN adhesion, indicating that oxidant-antioxidant balance at the EC interface is a critical factor modulating PMN-EC adhesive interactions. The results suggest that H2O2-induced PMN adhesion is dependent on the rapid induction of the ICAM-1 mRNA signal and the surface expression of ICAM-1 on EC.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1993

Adolescent cigarette consumption: the influence of attitudes and peer drug use.

Predictors of tobacco consumption were investigated with path analytic techniques using household survey data from 1,093 teenagers aged 13-17. When current smokers are compared to past or never smokers, pro-tobacco attitudes are always the most important predictor variable followed by friends' use of marijuana and own use of marijuana, suggesting that pro-tobacco attitudes are responsible for maintaining tobacco consumption. We infer that peer illicit drug use has the greatest effect in taking up smoking because it is the most important predictor of past smoker status compared to never smoking and it does not appear as such an important predictor of current use compared to never smoker status. Pro-tobacco attitudes are a consequence of smoking rather than an influence upon taking up smoking.

Adolescent↗
PubMed1993

DNA polymorphisms of apolipoprotein B in the population of Taiwan.

Four apolipoprotein B (apoB) genetic polymorphisms, the AluI, XbaI, MspI and EcoRI restriction fragment length polymorphisms (RFLPs), were analyzed for 162 individuals in Taiwan by polymerase chain reaction. Allele frequency determination revealed that this population has 0.86 AluI- (A-), 0.99 XbaI- (X-), 1.0 MspI+ (M+), and 0.98 EcoRI+ (E+) alleles. Major genotypes were A-/A- (0.75), X-/X- (0.98), M+/M+ (1.0) and E+/E+ (0.96). There were 0.22 A-/A+, 0.02 X-/X+ and 0.04 E+/E- heterozygous genotypes and one minor homozygous A+/A+ (0.03) genotype. The XbaI allele frequency is similar to that found in the Japanese population (XbaI- 0.96), but is significantly different from that in Caucasians (XbaI- 0.31-0.54). Significant differences (p < 0.001) between the Taiwanese and Caucasians were also observed for the AluI, EcoRI and MspI RFLP alleles of the apoB gene. More heterozygous genotypes are observed in Caucasians than in the Taiwanese.

Adult↗
PubMed1993

First alveolar-arterial oxygen gradient (AADO2) in mechanical ventilation as a predictor for duration of intubation in respiratory distress syndrome.

From January 1988 to May 1992, 33 premature infants (inborn, gestational age less than 35 weeks), put on respirator therapy (before six hours of age) due to severe respiratory distress syndrome (RDS), were studied to examine if the first alveolar-arterial oxygen gradient (AaDO2) after initiating mechanical ventilation could be used as a predictor of intubation duration. They were divided into three groups: nine cases without associated diseases or severe complications who were successfully extubated (group I), 10 cases with associated diseases or severe complications who were successfully extubated (group II), and 14 cases where death occurred before extubation (group III). After intubation, the relationship between the first AaDO2 and the intubation duration thereafter was examined. A significant correlation between AaDO2 and the number of days of intubation was demonstrated only in group I (r = 0.93, p < 0.001). Among the groups, the means of the gestational ages, Apgar scores, data of the first arterial blood gas sample and ventilator settings after intubation, and AaDO2 were not statistically different. The results suggest that the first AaDO2 cannot be used to predict mortality and morbidity, but it can be used as a predictor of the number of days of intubation in surviving RDS infants without associated diseases or severe complications. If a surviving patient with RDS is not extubated by the expected date, one should search for possible associated diseases or severe complications.

Blood Gas Analysis↗
PubMed1992

Sense and antisense cDNA transfection of CD36 (glycoprotein IV) in melanoma cells. Role of CD36 as a thrombospondin receptor.

Thrombospondin (TSP) is a multifunctional matrix and platelet glycoprotein that interacts with cell surfaces and may play a role in mediating cell adhesion, platelet aggregation, platelet-monocyte interactions, cell proliferation, angiogenesis, tumor metastasis, and protease generation. To clarify and confirm the function of CD36 (glycoprotein IV) as a TSP receptor, we now describe a transfected cell model using human melanoma cells genetically manipulated by sense or antisense cDNA transfection to express either high or near zero levels of CD36. Surface expression was confirmed by flow cytometry with monoclonal anti-CD36 IgG and quantified by measuring radiolabeled antibody binding. Bowes melanoma cells, which in their wild type did not express CD36 and did not bind radiolabeled TSP, when transfected with the sense construct bound TSP in a 1:1 stoichiometric ratio with CD36 expression. Conversely, C32 melanoma cells, which in their wild type expressed high levels of CD36 and bound radiolabeled TSP at a 1:1 stoichiometric ratio, did not express CD36 and did not bind TSP when transfected with an antisense construct. In addition, transfected Bowes cells and wild type C32 cells, unlike wild type Bowes cells, adhered to activated platelets in a TSP-dependent manner. These data, i.e. the gain of function with sense cDNA transfection and loss of function with antisense transfection, strongly support the TSP receptor function of CD36. The distribution of this protein in vascular cells and tissues and observations that it may participate in signal transduction events suggest that TSP-CD36 interactions may play a role in mediating some of the pathophysiological processes associated with TSP.

Antibodies, Monoclonal↗
PubMed1992

Childhood pedestrian injuries in the Perth metropolitan area.

OBJECTIVE: To examine the characteristics of childhood pedestrian injuries in the Perth metropolitan area from 1980 to 1989. DESIGN: Retrospective descriptive study. SETTING: Perth metropolitan area, Western Australia. PARTICIPANTS: Child pedestrians aged 0 to 14 years who were injured during the period 1 January 1980 to 31 December 1989. MAIN OUTCOME MEASURES: An extensive database which reported fatal and non-fatal motor vehicle collisions was used to obtain details on the child pedestrian, the vehicle involved in the collision, and the environmental factors related to these injuries. RESULTS: A total of 1282 child pedestrian injuries were reported in the 10 year period. Children aged between 5 and 9 years, and were overrepresented among those injured. This study also demonstrated a similar proportion of injuries involving the 10-14 year age group. Injuries frequently occurred mid block, on local urban roads, between the hours of 3 p.m. and 7 p.m., and a greater than expected proportion of drivers involved in these collisions were in the under-21 age category. To describe the pattern of childhood pedestrian injuries we calculated both age-specific injury rates, and injury rates based on the number of registered motor vehicles. The latter revealed a greater than 20-fold variation between local government areas. CONCLUSIONS: Further analytical research, incorporating a measure of the child pedestrian's exposure to roads and traffic is required to identify those features in the individual and the environment which have a significant influence on the likelihood of a collision. Such research is required to institute effective preventive measures.

Accidents↗
PubMed1992

Fibrin contact increases endothelial permeability to albumin.

We studied the effects of contact of bovine pulmonary artery endothelial cell monolayers with fibrin on the endothelial barrier function. Fibrin formed by clotting purified fibrinogen (0.5 to 3.0 mg/ml) with alpha-thrombin (1 U/ml) was added to endothelial monolayers and permeability measurements were made after fibrin removal. Fibrin incubation for 3 hours resulted in 2- to 5-fold increases in transendothelial 125I-albumin permeability. Permeability returned to baseline value within 3 hours after fibrin removal. Direct contact with fibrin was necessary for the response, since fibrin separated from the endothelium did not increase permeability. Contact with agarose (2 mg/ml) or fibrinogen (0.5 to 3.0 mg/ml) also did not increase endothelial permeability. Transmission electron microscopic examination indicated normal appearance of interendothelial junctions at a time when albumin permeability was increased and no overt evidence of endothelial injury. Incubation of fibrin with endothelial monolayers at 4 degrees C prevented the increase in albumin permeability. We examined the possibility that increased albumin transcytosis was responsible for fibrin's effect using 14C-sucrose (Mr = 342D), a lipid insoluble tracer. Fibrin increased sucrose flux by 1.5-fold compared to 2- to 5-fold increases in albumin flux. The results indicate that fibrin contact with the endothelial cell increases endothelial permeability. The effect of fibrin may involve activation of temperature-sensitive bulk phase transcytosis of albumin.

Albumins↗
PubMed1992

Neutrophil adhesion to TNF alpha-activated endothelial cells potentiates leukotriene B4 production.

Since adhesion of neutrophils (PMN) to endothelial cells may influence PMN activation responses, we examined whether adhesion of PMN to TNF alpha-activated human umbilical vein endothelial cells (HUVEC) stimulates leukotriene B4 (LTB4) production. Endothelial adhesivity towards PMN increased after HUVEC pretreatment with TNF alpha for 4 h. LTB4 production increased markedly in response to stimulation with arachidonic acid (20 microM) when PMN were added to the hyperadhesive HUVEC. In contrast, stimulation of PMN in suspension did not potentiate LTB4 production. LTB4 production persisted when PMN were applied to TNF alpha-pretreated HUVEC fixed with 1% paraformaldehyde excluding the possibility that metabolic activity of endothelium participates in this response. PMN adhesion to plastic and gelatin also enhanced LTB4 indicating that adhesion was a critical event in inducing LTB4 production. We used monoclonal antibodies (mAb) to adhesion molecules on endothelial cells (i.e., endothelial leukocyte adhesion molecule-1 (ELAM-1) and intercellular adhesion molecule-1 (ICAM-1)) or on PMN (CD18) to assess the role of PMN adhesion to the activated endothelium on LTB4 potentiation. Both anti-ELAM-1 mAb and anti-ICAM-1 mAb inhibited PMN adhesion (by 55 and 41%, respectively) as well as LTB4 production (by 65 and 50%, respectively). Anti-CD18 mAb also reduced the adhesion (65%) and the LTB4 production (66%). Furthermore, combination of anti-ELAM-1 mAb (H18/7) and anti-ICAM-1 mAb (RR1/1) or of anti-ELAM-1 mAb (H18/7) and anti-CD18 mAb (IB4) had an additive effect in inhibiting both PMN adhesion as well as LTB4 production. PMN adherence to immobilized recombinant soluble rELAM-1 or rICAM-1 also increased LTB4 production, which was prevented with relevant mAbs. However, neither rELAM-1 nor rICAM-1 stimulated LTB4 production of PMN in suspension. We conclude that PMN adhesion to TNF alpha-stimulated endothelial cells enhances LTB4 production by PMN, a response activated by binding of PMN to expressed endothelial cell surface adhesion molecules.

Antigens, CD↗
PubMed1992

Stages of drug use: a community survey of Perth teenagers.

A Guttman stages of drug use model was confirmed for Australian youth in this systematic household survey of 13-17-year-olds in Perth (n = 1093). The same model held for both sexes and all ages although the model was more efficient for the older youth. General drug use prevalence, expansion of drug repertoire and frequency of use all increased with age. Multiple drug use was prevalent. Marijuana use was not a necessary stage for the progression to other illicit drug use as 29% of current users of other illicit drugs reported never using marijuana. The hazard rate for use of marijuana or other illicit drugs, if one was a current tobacco smoker, was high. Alcohol and tobacco were implicated as important 'gateway' drugs though hazard rates showed tobacco to be the more important of the two. Implications of the study are that delaying or eliminating the onset of tobacco use are important goals of prevention programmes and that multiple drug use should be recognized and addressed in health education programmes for youth.

Adolescent↗
PubMed1992

Landing patterns in netball: analysis of an international game.

The passing and landing patterns among netball players were investigated by examining all the 595 passes in an international match between Australia and New Zealand. Intra-class correlations were used to test inter-observer reliability. The independence of two variables was tested using a Pearson chi 2 test and a contingency coefficient was used to assess the degree of association between variables. An inter-rater reliability in the identification of movement patterns was 0.99. Most of the landings observed in this match were on the forefoot and not the hindfoot as generally reported in controlled experiments. Only 14% of the players leapt to receive a pass compared with 76% reported earlier under controlled environments. The distribution of passing techniques unexpectedly showed that approximately 50% of all the players did not reach for the ball as it was thrown directly to them. However, over 70% of the players threw straight passes which were mainly received in the chest quadrant and other types of passes such as loop, bounce and rebound were used less frequently. Nearly 50% of all players used a right-handed pass to dispose of the ball, while the next most popular pass was to use both hands (40.2%). Landing and passing patterns differed between players in different positions. Footfall patterns on landing after a catch were associated with the trajectory of the ball.

Australia↗