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Biomedical subjects

J Woo

Publications and source records attributed to J Woo.

At least 19 recordsLinked to original sources
PubMed1992

Preformed lymphocytotoxic antibodies: the effects of class, titer and specificity on liver vs. heart allografts.

The effect on liver and heart allograft survival (ACI rats to Lewis rats) was studied after three methods of recipient presensitization and after different intervals between sensitization and transplantation. With comparable lymphocytotoxic antibody titers, liver allografts always survived longer than heart grafts. The titer, class and specificity of the antibodies varied with the method of sensitization. Four skin grafts produced IgG and IgM lymphocytotoxic antibody titers of 1:2,000 to 4,000. The IgG fraction was shown to have hepatic vascular endothelial specificity by indirect immunofluorescence. These primed recipients hyperacutely rejected both heart and liver allografts, which showed vascular deposition of IgG antibodies. Survival of either kind of graft was inversely proportional to the lymphocytotoxic antibody titer and length of time after placement of the last skin graft. Presensitization with a single heterotopic heart graft produced an even higher mixed IgG and IgM lymphocytotoxic antibody titer of 1:8,000 but with less IgG vascular endothelial specificity. These animals also hyperacutely rejected heart or liver grafts with tissue deposition of IgG but less consistently and with a weaker correlation with lymphocytotoxic antibody titers and time after sensitization. Sensitization with two pretransplant blood transfusions produced the lowest titer (1:500 to 1,000) and the least IgG vascular endothelial specificity. Liver allograft survival was routinely enhanced in these animals, and little effect was seen on heart grafts. Collectively, the experiments showed that the liver is not only resistant to antibody-mediated rejection relative to the heart but is more easily enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Serum intact parathyroid hormone levels in elderly Chinese females with hip fracture.

Serum intact parathyroid hormone (PTH), 25 hydroxyvitamin D(25OHD), 1,25 dihydroxyvitamin D (1,25(OH)2D), albumin, and ionized calcium were measured in 61 Chinese female patients with hip fracture and 61 control subjects. Hip fracture patients had low albumin, ionized calcium, and 250HD levels. Serum PTH and 1,25(OH)2D values were not different between the two groups. We conclude that although 250HD level in hip fracture patients is low, there is no evidence of secondary hyperparathyroidism, suggesting that the low 250HD levels may be a secondary phenomenon in response to the fracture.

Aged↗
PubMed1992

The effects of calcium supplementation and exercise on bone density in elderly Chinese women.

A randomized controlled trial was carried out to determine whether calcium supplementation and load-bearing exercise can increase or maintain bone mass in the elderly. Fifty Chinese women, aged 62-92 years, living in a hostel for the elderly in Hong Kong were randomized to enter one of four treatment groups: (I) calcium supplementation of 800 mg (as calcium lactate gluconate) daily; (II) load-bearing exercise four times a week plus a daily placebo tablet; (III) calcium supplementation daily and load-bearing exercise four times a week; (IV) a placebo tablet daily. The interventions went on for 10 months. The bone mineral density (BMD) was measured at three sites in the hip (femoral neck, Ward's triangle and intertrochanteric area) and the L2-4 level of the spine. The percentage change in BMD in 10 months was used as the main outcome measurement. The parathyroid hormone level and indices of bone metabolism were also measured before and after 10 months of intervention. The BMD at Ward's triangle and the intertrochanteric area increased significantly in subjects on calcium supplement (p less than 0.05), but there was no significant change at the spine and femoral neck. Exercise had no effect on bone loss at any site. However, the results of two-way analysis of variance showed a significant joint effect of calcium supplements and exercise at the femoral neck (p less than 0.05), but not at the other sites. The parathyroid hormone levels fell significantly in subjects on calcium supplements (p less than 0.01). Calcium supplement in the form of calcium lactate gluconate was adequately absorbed in elderly Chinese women with a calcium intake of less than 300 mg per day. It was effective in reducing bone loss at the hip, and there may be interaction effects with exercise in maintaining bone density.

Aged↗
PubMed1992

Microalbuminuria and other cardiovascular risk factors in nondiabetic subjects.

The association between urinary albumin:creatinine ratio and other cardiovascular risk factors such as age, blood pressure, obesity, glycemic indices, insulin and lipid profile was examined in a population in a Chinese community consisting of 795 men (mean age 35.8 +/- 8.8 yr) and 538 women (mean age 37.9 +/- 8.9 yr) with a normal glucose tolerance defined by WHO criteria. Men with a urinary albumin:creatinine ratio above the 90th percentile had higher systolic and diastolic blood pressures, fasting plasma glucose, 2-h glucose after a 75 g oral glucose load, and fasting serum insulin. Women with high urinary albumin:creatinine values had higher systolic and diastolic blood pressures, body mass index, waist-hip ratio, fasting insulin and triglycerides. Multivariate analysis showed that only systolic blood pressure and fasting glucose in men, and diastolic blood pressure and fasting insulin in women, independently contributed to urinary albumin:creatinine. When the effect of blood pressure was eliminated by excluding subjects with systolic blood pressure > 140 and diastolic > 90 mm Hg, only fasting insulin was associated with urinary albumin:creatinine in women. No associations were found for men. We conclude that microalbuminuria may be a marker for cardiovascular disease only because of its association with blood pressure in men, while in women, there is an additional independent association with fasting serum insulin.

Adult↗
PubMed1992

Compliance with infection control procedures among California orthodontists.

We conducted a survey of a random sample of California orthodontists and of general dentists to compare their infection control procedures. Questionnaires were returned by 124 orthodontists (56% response rate) and 126 general dentists (61% response rate). Eighteen questions were asked covering practice profile, perception of risk from hepatitis B virus (HBV) and human immunodeficiency virus (HIV), exposure to blood, barrier protection used, and sterilization and disinfection procedures. Gloves always were worn by 80% of the orthodontists sampled, 63% always wore glasses, and 59% changed gloves between patients. Orthodontists sterilized their instruments 66% of the time and pliers 49% of the time. Compared with general dentists, orthodontists' perception of risk, use of barrier protection, and sterilization and disinfection procedures were lower in all areas. Our data suggest that poorer performance may be because orthodontists: (1) perceive their younger population of patients at less risk for HBV and HIV; (2) treat 2.5 times as many patients, which increases the costs of infection control; (3) do not use invasive procedures; and (4) perceive that glove use decreases dexterity. Orthodontists should follow the American Dental Association/Council on Dental Therapeutics infection control guidelines for universal precautions. To meet these guidelines, orthodontists still need improvement in all aspects of their infection control procedures.

Adolescent↗
PubMed1992

A prospective evaluation of prehospital 12-lead ECG application in chest pain patients.

The objective of this study was to prospectively determine the utility, efficiency, and reliability of early prehospital 12-lead electrocardiogram (ECG) application, the improvement in prehospital diagnostic accuracy, and paramedic and base physician opinions regarding early application of prehospital 12-lead ECGs in a broad range of stable chest pain patients. The patient population consisted of cooperative, stable adult prehospital patients with a chief complaint of nontraumatic chest pain of presumed ischemic origin. From July 17, 1989 through January 1, 1990 paramedics acquired prehospital 12-lead ECGs on 680 stable adult chest pain patients. Factors affecting prehospital 12-lead ECG application were evaluated. Paramedic application of prehospital 12-lead ECGs was found to be efficient and reliable, and it can be applied to most cooperative stable adult prehospital chest pain patients. Prehospital 12-lead ECGs significantly improve base physicians' diagnostic accuracy in myocardial infarction, angina, and nonischemic chest pain patients. Paramedic and base physicians' opinions regarding early application of prehospital 12-lead ECGs during patient evaluation were favorable.

Chest Pain↗
PubMed1992

The effects of rapamycin on humoral immunity in vivo. Suppression of primary responses but not of ongoing alloantibody synthesis or memory responses.

The effect of rapamycin on primary and secondary alloantibody responses to major histocompatibility complex class I antigens was investigated in inbred rat strains. Primary anti-MHC class I alloantibody responses, detected by indirect hemagglutination and complement-dependent cytotoxicity assays, were abrogated in high-responder WAG (RT1u) recipients of DA (RT1a) blood transfusions, given on days 0 and 7 of a 14-day course of rapamycin (3 mg/kg/day). Antibody class studies showed that both IgM and IgG responses were equally effectively inhibited. Moreover, when these animals were rechallenged with DA transfusions, 28 days after drug withdrawal, they exhibited donor-specific humoral unresponsiveness. Similar results were observed in cyclosporine-treated rats. In preimmunized high-responder LEW (RT1(1)) rats with high titer anti-DA class I alloantibodies, a 35-day course of rapamycin (3 mg/kg/day) had no significant suppressive effect on serum alloantibody levels when compared with untreated preimmunized control animals. WAG rats were immunized by DA transfusions and serum antibody levels then allowed to decay over 16 weeks. The animals were then challenged with a further DA transfusion given on the second day of a 14-day course of rapamycin (3 mg/kg/day). Alloantibody responses to the challenge transfusion in this group were not, however, significantly suppressed when compared with a non-drug-treated control group. The results of this study indicate that rapamycin is a potent inhibitor of primary alloantibody synthesis in high-responder rat strains, but does not significantly suppress alloantibody synthesis in animals with established humoral reactivity. These results may be of relevance if rapamycin is to be used in clinical renal transplantation, because in man similar antibodies mediate hyperacute rejection, and when they develop after transplantation are associated with very high rates of rejection.

Animals↗
PubMed1992

Age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of bone metabolism in Chinese women.

OBJECTIVE: To study the age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of calcium metabolism in Chinese women who habitually have a low calcium intake. DESIGN: Cross-sectional study. SUBJECTS: One hundred and fifty-six healthy Chinese women aged 20-83 years. None were on any medication or vitamin supplements. Subjects over the age of 60 years were all living in a hostel; younger subjects were nurses or subjects attending a family clinic for minor illnesses. MEASUREMENTS: Fasting blood and urine samples were collected for biochemical measurements and calcium absorption was measured using 45Ca by the method of Marshall and Nordin. Bone density was measured by dual energy X-ray densitometry (Norland X R20 X-ray bone densitometer) at the left hip and lumbar spine. Serum parathyroid hormone was measured by a chemiluminometric assay. RESULTS: Plasma ionized calcium concentration, alkaline phosphatase, bicarbonate, plasma creatinine and serum B2 microglobulin were significantly higher in the elderly than in the young, whereas plasma phosphate and the anion gap were higher in the young. Urinary excretion of calcium, phosphate and hydroxyproline were all higher in older women. Plasma parathyroid hormone concentration was positively correlated with age even after taking into account the decline in renal function (as indicated by the rise in B2 microglobulin (r = 0.506, P less than 0.001). Serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were not lower in the older women. Fractional calcium absorption from an oral load of radiolabelled calcium was significantly lower in the older women and 37% of the older women were below the 2.5 percentile found in the younger women. Bone density measured by dual energy X-ray densitometry was also significantly lower in the elderly. CONCLUSION: In Chinese women there is an increase in PTH and a decrease in calcium absorption with age in spite of the presence of normal vitamin D metabolites.

Absorption↗
PubMed1992

Elderly subjects aged 70 years and above have different risk factors for ischemic and hemorrhagic strokes compared to younger subjects.

OBJECTIVE: To compare risk factors for ischemic and hemorrhagic strokes in subjects aged 70 years and above with those in younger subjects. DESIGN: Case control study, with controls matched for age and sex in 5-year age groups. SETTING: A general district hospital in Hong Kong with a catchment population of over 1 million. PATIENTS: All patients admitted consecutively over a 6-month period. Classification of stroke was by neurological examination and CT scan, or autopsy if death occurred before CT scanning could be performed. EXCLUSION CRITERIA: onset of ictus greater than 48 hours before admission, those with previous stroke, subarachnoid hemorrhage, or embolic stroke from rheumatic heart disease, and those with liver, renal, biliary, or thyroid diseases. For ischemic strokes, 78 pairs less than 70 years and 121 pairs greater than or equal to 70 years were recruited. For hemorrhagic strokes, the numbers were 40 and 39, respectively. RESULTS: For ischemic strokes, atrial fibrillation and the presence of ischemic heart disease were risk factors only for those aged 70 years and above, while smoking and left ventricular hypertrophy were risk factors only for those below 70 years. Hypertension and glucose intolerance were risk factors for both age groups, although the effect of glucose intolerance was less marked in the older group. No marked difference in serum lipids and lipoproteins as risk factors was observed between the two age groups. Hypertension was the only demonstrable risk factor for hemorrhagic stroke in the younger, but not in the older, group. CONCLUSION: Risk factors for ischemic and hemorrhagic strokes are different in elderly compared with younger subjects, with the possibility that certain risk factors for ischemic strokes, in contrast to those for hemorrhagic strokes, may be modifiable even in subjects aged 70 years or above.

Age Factors↗
PubMed1992

Hospital arrival time after onset of stroke.

To estimate the proportion of patients with stroke likely to be eligible for a trial of anticoagulant treatment for acute ischaemic stroke, the interval between onset of symptoms and arrival at hospital was analysed prospectively. Of 773 patients with stroke admitted in one year, 63% arrived at hospital within 12 hours, 76% within 24 hours, and 85% within 48 hours of ictus. The arrival time varied significantly with stroke subtype. Patients with intracerebral haemorrhage tended to arrive earlier than those with cerebral infarct, who arrived sooner than those with lacunar infarct. The results suggest that about half of all patients with ischaemic stroke in Hong Kong would present within 12 hours of ictus, in time for inclusion in a therapeutic trial.

Aged↗
PubMed1992

Prediction of mortality in patients in acute medical wards using basic laboratory and anthropometric data.

The value of anthropometric and biochemical indices in predicting short-term mortality among patients in general medical wards was assessed in 294 patients admitted consecutively to a district hospital over a one month period. Using a stepwise logistic regression model and supported by the linear discriminant analysis method, mortality within 3 months could be predicted with sensitivity of 83% and specificity of 84% using the following variables: sex, functional ability, urea, total protein, alkaline phosphatase and albumin-adjusted calcium. Addition of anthropometric values and biochemical nutritional indices did little to improve the accuracy of the prediction, contrary to previous findings among surgical patients and elderly residents of long-term care institutions.

Activities of Daily Living↗
PubMed1992

Factors influencing long-term survival and disability among three-month stroke survivors.

216 survivors of acute stroke were studied 3 months postictus to determine predictors of long-term survival and disability 20 months after the initial stroke. Factors predicting mortality were, in order of importance, old age, a history of ischaemic heart disease, low mental-test score, low serum cholesterol concentration, low Glasgow Coma Score on admission, and the presence of left ventricular hypertrophy. 73% of subjects were correctly classified by discriminant function analysis using these variables. Factors predicting poor functional outcome (Barthel Index 15) were a low Barthel Index at 3 months, old age, low mental-test score at 3 months and a low Glasgow Coma Score on admission. 70% of subjects were correctly classified into 3 functional-outcome groups using these variables. Stroke subtype and size, position, and the territory of the lesion on brain CT did not influence long-term outcome. We conclude that factors affecting long-term survival and disability are different from those affecting outcome immediately after stroke.

Aged↗
PubMed1992

Stroke subtypes among Chinese living in Hong Kong: the Shatin Stroke Registry.

The Shatin Stroke Registry is a prospective study of all patients admitted with acute stroke to a general hospital in Hong Kong where the population is predominantly Chinese. Each patient was examined by a neurologist and 95.5% of the patients had a brain CT. Of 777 patients included in the study, 44.0% had a cortical/subcortical infarct, 18.5% a supratentorial lacunar infarct, 24.2% a supratentorial intracerebral hemorrhage, 5.8% brainstem/cerebellar infarct, 2.9% a brainstem/cerebellar hemorrhage, and 4.5% an uncertain diagnosis. The overall 30-day case fatality rate was 25.4%. Comparison with five stroke registries from the West suggests that intracerebral hemorrhage occurs between two and three times more frequently in the Chinese than in Westerners. Whether there is any difference in the relative frequencies for lacunar infarction remains unclear.

Adult↗
PubMed1992

Assessment of glucose tolerance test criteria for diagnosis of diabetes in Chinese subjects.

OBJECTIVE: To examine and compare WHO diagnostic criteria for diabetes mellitus. RESEARCH DESIGN AND METHOD: The relationship between FPG and 2-h glucose are examined in 680 OGTTs with a quadratic regression model and ROC analysis. Simultaneous measurements of HbA1 and fructosamine are also compared with multiple linear regression. RESULTS: Two hundred eighteen subjects (32%) had 2-h glucose greater than or equal to 11.1 mM, of which only 86 had FPG greater than or equal to 7.8 mM. Only 2 subjects had FPG greater than 7.8 mM and 2-h glucose less than 7.8 mM. Of subjects with 2-h glucose less than 7.8 mM (n = 332), only 9 had FPG greater than 6.0 mM. From the quadratic model, the predicted FPG corresponding to 2-h glucose = 11.1 mM was 5.7 mM, whereas the predicted 2-h glucose corresponding to FPG = 7.8 mM was 15.2 mM. ROC analysis showed that, with 2-h glucose greater than or equal to 11.1 mM as indicating diabetes, an FPG of 5.6 mM gave an intersect for sensitivity and specificity of 87%. HbA1 and fructosamine correlated more closely with 2-h glucose and area under the OGTT curve than with FPG. CONCLUSIONS: Given that a 2-h glucose cutoff of 11.1 mM can be justified from other studies, our results suggest that the FPG cutoff of 7.8 mM when used for screening purposes should be reduced. At a suggested value of 7.0 mM, specificity remains 98.5%, whereas sensitivity increases to 57%.

China↗