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Biomedical subjects

D Wong

Publications and source records attributed to D Wong.

At least 235 records · Page 13Linked to original sources
PubMed1989

Respiratory syncytial virus alters electrophysiologic properties in cotton rat airway epithelium.

The effect of respiratory syncytial virus (RSV) infection on the electrophysiologic properties of the airway epithelium was studied in tracheas obtained from cotton rats, after in vivo exposure to the virus. RSV infection was documented by tissue culture infectivity and immunofluorescent antibody techniques. Light microscopic studies of the tracheas 72 hours after exposure to RSV revealed normal epithelial morphology. RSV infection produced a 28% decrease in short-circuit current (Isc) and an almost 100% increase in tissue resistance. The decrease in Isc was partially attributed to a decrease in Cl secretion, while the increase in tissue resistance was associated with significant restriction to sodium and chloride movement through the paracellular pathway in RSV-infected tracheas. We conclude from these studies that RSV infection in the cotton rat trachea produces significant changes in active and passive ion flows. Alterations in ion transport across the airway epithelium may result in changes in secondary water transport across the airways and may contribute to the pathophysiology of RSV bronchiolitis and other locally invasive mucosal viral infections in children.

Airway Resistance↗
PubMed1989

Studies on the accumulation of serum proteins in zymosan-induced inflammation in mouse peritoneum.

Inflammatory responses were induced in mice by intraperitoneal (i.p.) injection of zymosan. This resulted in a rapid accumulation of protein in the peritoneum that was dependent on the time of the injection and concentration of zymosan used. Though other stimuli, e.g., phorbol myristate acetate, lipopolysaccharide, carrageenan and latex beads, caused the accumulation of proteins, the maximum response was obtained only with zymosan. Injection of free fatty acids were unable to induce protein accumulation in peritoneum. Factors which decreased leukotriene production in mouse peritoneum, i.e., dietary n-3 fatty acids essential fatty acid deficient diets, did not affect protein accumulation. Direct injection of leukotrienes also failed to induce protein accumulation. Analyses revealed that the proteins were similar to serum proteins, indicating that zymosan causes the leakage of serum proteins into peritoneum.

Animals↗
PubMed1989

A closed microsurgical technique for anterior vitrectomy using a continuous air infusion.

A new technique of anterior vitrectomy using a continuous air infusion is described. It has a number of advantages over conventional techniques and is recommended for the management of vitreous loss during cataract extraction. The vitreous gel is displaced posteriorly by the surface tension of an air bubble. The identification of vitreous strands is facilitated by the air/vitreous interface. Air in the anterior chamber reduces the refractive power of the cornea, providing direct visualisation of the posterior segment.

Air↗
PubMed1989

Risk factors for basal cell carcinoma.

Completed questionnaires regarding suspected risk factors for basal cell carcinoma (BCC) were completed by 538 basal cell carcinoma patients and 738 age-, sex-, and location-matched controls in Saskatchewan. Significant risk factors were identified using chi2 analyses. Relative risks were subsequently computed. The following relative risks were identified: occupation of farming, 1.29; prominent freckles in childhood, 1.23; family history of skin cancer, 1.22; sunburn, 1.19; Irish, Scottish, Welsh mother, 1.19; light skin color, 1.18; red/blond hair color, 1.16; and working outdoors more than 3 hours/day in winter, 1.13: The average age of cases of BCC with a family history of skin cancer was significantly lower than cases of BCC with no family history of skin cancer (63.86 vs. 67.02 years, p = 0.018). No association was noted between BCC and psoriasis.

Adult↗
PubMed1989

Chart for visual acuity screening.

The statistical basis underlying the use of several visual acuity charts is examined. A new chart which offers theoretical and practical advantages for visual acuity screening is described.

Humans↗
PubMed1989

Nuclear magnetic resonance study of regional metabolism after forebrain ischemia in rats.

Proton nuclear magnetic resonance (NMR) spectroscopy of perchloric acid tissue extracts has been used to follow serial postischemic changes in the levels of metabolites in the hippocampus, cerebellum, frontal lobes, and parietal/occipital lobes in a rat model of short-duration (10 minutes) forebrain ischemia. Shortly (10 minutes, 1 hour) after the ischemic insult, the levels of the amino acids alanine and gamma-aminobutyric acid are elevated and that of glutamate is depressed in all regions except the cerebellum. The levels of these species return to control values by 24 hours postischemia. No changes are observed in the levels of aspartate or N-acetylaspartate. Greatly elevated levels of acetate 10 minutes postischemia, particularly in the hippocampus, may be due in part to metabolic degradation of fatty acids released due to membrane breakdown. Elevated levels of lactate persist for up to 7 days postischemia, suggesting that normal mitochondrial functioning is not fully restored following the ischemic insult.

Acetates↗
PubMed1989

Postpartum immunization with rubella virus vaccine and antibody response in breast-feeding infants.

Women who were susceptible to rubella, whether they had elected to breast-feed or formula-feed their infants, received immunization with subcutaneously administered rubella antibody 27/3 live, attenuated rubella virus vaccine in the postpartum period. The breast-fed or formula-fed infants of these mothers who had been immunized subsequently received active immunization with the rubella antibody 27/3 vaccine at 15 to 18 months of age. A second group of naturally immune women who were seropositive for rubella did not receive immunization after childbirth. However, infants of naturally immune mothers who did not receive immunization received immunization with the rubella vaccine and served as controls. Seroconversion for rubella antibody developed in over 94% of susceptible women who were seronegative for rubella after postpartum immunization. The infants of these mothers had no rubella antibody activity in the cord blood; however, 13% of such infants exhibited rubella antibody in serum at 6 months of age. On the other hand, 44% of breast-fed infants of naturally immune mothers (controls) demonstrated rubella antibody activity at 6 months of age. Subsequent immunization with rubella vaccine in breast-fed infants whose mothers had received postpartum immunization resulted in a serum antibody response that was similar to the response observed in the formula-fed infants or the infants of naturally immune mothers who had not received immunization. These data suggest that early neonatal exposure to the rubella virus in breast milk does not enhance or suppress subsequent responses to current programs of rubella vaccination in early childhood.

Antibodies, Viral↗
PubMed1988

Functional zones in the auditory cortex of the echolocating bat, Myotis lucifugus.

Neurophysiological mapping experiments in the auditory cortex of the frequency-modulated bat, Myotis lucifugus, reveal 3 functional subregions: a tonotopic zone located dorsally, a delay-sensitive zone more ventrally, and an intermediate zone of major overlap. The unique finding of an overlapping cortical region representing both spectral and time-delay information of echoes is intriguing in view of a recent behavioral study suggesting the convergence of such echo cues in auditory perception. (Simmons et al., Soc. Neurosci. Abstr., 13 [1987] 870).

Acoustic Stimulation↗
PubMed1988

Ultrasonic Doppler studies of the vitreous.

Simultaneous 'real-time' B-mode and doppler ultrasound techniques were used to study movements of the detached vitreous gel which occurred during duction movements of the eye. The velocity of sound scatterers within the vitreous gel were measured and it was possible to differentiate quantitatively gels which were 'stiff' from those which were 'sloppy'. Information obtained using this technique may throw light on the pathogenesis of rhegmatogenous retinal detachment and assist in the quantitative assessment of retinal mobility in eyes with vitreoretinopathies.

Eye Diseases↗
PubMed1988

Non-contact retinal photocoagulation using the Volk +90 dioptre lens.

The Volk +90 dioptre lens offers a stereoscopic, wide-field (60 degrees) retinal view without the disadvantage of contact funduscopy. Used in conjunction with the slit-lamp, the lens gives a bright, inverted, magnified image of the posterior segment. Its uses in the diagnosis of posterior pole pathology, detailed examination of the optic disc and fundus photography are well established.

Humans↗
PubMed1988

Contact allergy to gold after systemic administration of gold for rheumatoid arthritis.

A patient with seropositive, nodular rheumatoid arthritis (RA) developed contact allergy to gold jewellery following a severe skin rash which occurred after 13 weeks of treatment with sodium aurothiomalate. Patch testing confirmed that the contact allergy was due to gold. This is the first proved case of contact allergy to gold or any other compound initiated by systemic administration of the allergen.

Arthritis, Rheumatoid↗
PubMed1988

Neuropsychological and neuroradiological correlates in Huntington's disease.

Measurements of cortical and subcortical atrophy were made on CT scans of 34 patients with Huntington's disease. Significant correlations were found between the bicaudate ratio (BCR) and an eye movement scale (r = 0.44, p less than 0.01), and activities of daily living scale (r = 0.57, p less than 0.001) and the Mini-Mental State Exam (r = 0.49, p less than 0.01). No correlations were found between BCR values and severity of chorea or voluntary motor impairment. A detailed neuropsychological evaluation of 18 Huntington's disease patients showed significant correlations between the BCR and Symbol Digit Modalities test (r = 0.65, p less than 0.01), and parts A (r = 0.72, p less than 0.001) and B (r = 0.80, p less than 0.0001) of the Trail Making Test. These data support work in primates that demonstrates the role of the caudate nucleus in cognitive and oculomotor functions, but not in motor control (which is governed by putamino-subthalamic systems). The specific cognitive skills correlated with caudate atrophy in Huntington's disease are those reported in primate work to be served by the frontal-caudate loop system: eye movements, conceptual tracking, set shifting and psychomotor speed.

Adolescent↗
PubMed1988

Interactive effects of systemically administered salbutamol and aminophylline in patients with chronic obstructive pulmonary disease.

It has been previously shown that inhaled salbutamol (S) and intravenous aminophylline (A) have an additive effect as bronchodilators in patients with chronic obstructive pulmonary disease (COPD). This additive effect could be due to different modes of action or different distributions of drug. In order to investigate the additive effect of S and A when administered by the same route, we studied eight patients 63.4 +/- 1.84 yr of age (mean +/- SEM), with long-standing COPD (FEV1, 0.96 +/- 0.12 L) by giving them intravenous A and S. A double-blind, cross-over study was performed on two separate days by administering either A followed by S or vice versa. Each drug when given alone increased the FEV1 significantly (p less than 0.01). The mean increase was 0.17 +/- 0.06 L (18% of baseline) for S and 0.15 +/- 0.05 L (17% of baseline) for A. The FEV1 increased 0.07 +/- 0.02 L when S was added to A (95% confidence interval, 0.02 to 0.12, 7% of baseline), and when A was added to S 0.05 +/- 0.03 L (95% confidence interval, -0.02 to 0.12, 6% of baseline). Neither change was significant. Heart rate (HR) was increased significantly (p less than 0.01) by S (22 +/- 3.4%), but not by A when it was given first. However, addition of the second drug increased HR significantly (p less than 0.01) from HR with one drug alone; the mean increase was 31 +/- 8.5% of baseline with the addition of S, and 19 +/- 4.06% of baseline with the addition of A.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuterol↗
PubMed1988

Fundus biomicroscopy: a comparison of four methods.

Funduscopic examination utilizing the biomicroscope is extremely valuable in the detection, diagnosis, and management of ocular disease. A variety of lenses are currently available for detailed examination of the posterior vitreous cavity and the retina. This paper discusses the optical principles and the various attributes of four lenses relative to magnification, field of view, clinical application and ease of use.

Contact Lenses↗
PubMed1987

Serial acquisition of data to predict one-year mortality rate after acute myocardial infarction.

Eight hundred sixty-six patients with acute myocardial infarction (AMI) were enrolled in a prospective study to determine optimal predictors of long-term prognosis. During 12-month (mean) follow-up there were 65 cardiac deaths and 21 nonfatal repeat AMIs. Twenty-nine variables (from the history, physical examination, serum chemistries, ambulatory monitor, radionuclide ventriculogram and exercise test) were arranged into in 5 sequential groups according to the time at which results became available during hospitalization. Multivariate analysis (logistic regression) and receiver-operator characteristic curves were used to assess improvement in prediction of mortality or repeat AMI by addition of each group of variables. The first group of independent predictors included rales, left bundle branch block and symptom status at 1 month before admission. Addition of information from ambulatory monitoring or serum chemistry did not improve prediction. Radionuclide ejection fraction made a statistically significant, independent contribution to mortality prediction. Of the final group the only exercise test variable that contributed independently to prediction was whether the patients took the test. However, receiver-operator characteristic curves showed that improvement in sensitivity and specificity by addition of information from the radionuclide scan and exercise test was clinically insignificant. Our results imply that costly tests after AMI should be reserved for specific indications and not applied universally for prognosis. Although these tests were highly predictive individually, each test generally added little to preexisting prognostic information.

Follow-Up Studies↗
PubMed1987

Pars plana vitrectomy for retinal detachment with unseen retinal holes.

A study was made of a consecutive series of 47 cases of rhegmatogenous retinal detachment treated by pars plana vitrectomy in which no holes were identified preoperatively. The view of the fundus during preoperative examination varied from being totally clear to completely obscured by media opacities. The role of pars plana vitrectomy in finding retinal holes peroperatively is considered. The incidence of discovering holes and the locations of those found at the time of surgery are presented. The significance of these findings is discussed. Where the preoperative view was good and the extent of proliferative vitreoretinopathy (PVR) did not exceed grade C2, retinal reattachment was achieved in 75% of the cases. A review made of a similar group of patients treated with conventional retinal buckling before the introduction of pars plana vitrectomy revealed that successful retinal reattachment was achieved in 70% of cases. The study concludes that pars plana vitrectomy, while being necessary for cases of rhegmatogenous retinal detachment when the view of the retina is obscured, will not always reveal the presence of a retinal break. If the preoperative view of the retina was good and the extent of PVR did not exceed grade C2, pars plana vitrectomy did not seem to offer obvious advantages over conventional buckling procedures.

Humans↗
PubMed1987

Expression of pre-S gene-encoded proteins in liver and serum during chronic hepatitis B virus infection in comparison to other markers of active virus replication.

Pre-S gene-encoded proteins of the hepatitis B virus (HBV) were studied in the liver by immunofluorescence and in serum by radioimmunoassay in 30 patients with chronic HBV infection. The results were compared with molecular hybridization analysis of HBV-DNA in liver and serum, with serum hepatitis B e antigen/antibody (HBeAg/anti-HBe) status and with underlying liver histology. Pre-S peptides were detected in the serum of 11 patients, 10 of whom were positive for serum HBV-DNA and/or liver hepatitis B core antigen. Only 4 of these patients were HBeAg positive. The prevalence of serum pre-S among HBV replicating carriers was 59% (10/17) compared to only 8% (1/13) among those with non-replicating virus (P less than 0.01). All patients with circulating pre-S peptides had active liver disease. Anti-pre-S was detected in the serum of only 4 patients, 3 with integrated HBV-DNA. In contrast to serum findings, pre-S peptides were detected in the liver of all patients with histochemically demonstrable hepatitis B surface antigen (HBsAg), regardless of HBV replicative status. HBsAg carriers with integrated HBV-DNA had abundant cytoplasmic pre-S1 and pre-S2 localized in numerous ground-glass hepatocytes. It is concluded that pre-S peptides are usually displayed in the liver simultaneously with histochemically detectable HBsAg; they are secreted in the serum in association with high HBV replication and release of HBV particles, but in the absence of episomal HBV replication, pre-S peptides seem to be largely retained within hepatocytic membranes.

Adult↗