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We lead multidisciplinary applied research and training to rethink the way health care is delivered in general practice and across the community.
A 3-year follow-up study of social, lifestyle and health predictors of cognitive impairment in a Chinese older cohort.
BACKGROUND: Longitudinal data on the older population in the Asian setting are limited. This paper reports the factors associated with the development of cognitive impairment (CI) in a cohort of Chinese elderly aged > or =70 years. METHODS: The study cohort comprising 2030 subjects aged > or =70 years was assembled in 1991-1992 and followed for 36 months. Baseline information on cognitive function, as well as a number of social and health variables were obtained through face-to-face interview at the respondent's place of residence. The outcome variable was the development of CI among 988 cohort members who were initially free from CI, and who could be contacted at the 36-month follow-up. The instrument used to assess CI was based on the information/orientation part of the Clifton Assessment Procedure for the elderly (CAPE), using a cut-off point of 7. RESULTS: Of the men, 6.7%, but 22.2% of women had CI at 3-year follow-up. The age-adjusted annual incidence of CI was 1.52% in men, and 6.37% in women. Multivariate logistic regression analysis showed that women had a 2.5-fold increased risk of having CI, compared with men. The risk increased by about 1.5-fold with every 5-year increase in age. Slow gait time, as assessed by the 16-foot walk, was a predictor of CI in both sexes (odds ratio [OR] = 1.03 per second increase, 95% CI : 1.0-1.07). Men residing in institutions had a 4.4-fold increased risk of having CI (95% CI : 1.7-11.1) compared with those residing in community, while the OR among women was 2.5 (95% CI : 1.3-4.9). Among women, no formal education increased the risk of having CI by 3.2-fold (95% CI : 1.8-5.5). Income dependency also increased the risk of CI by about fourfold, and no exercise at baseline was associated with a twofold increased risk of CI. Incident stroke during follow-up also increased the risk of CI (OR = 8.4, 95% CI : 1.2-59.4). CONCLUSIONS: Older age and female sex were independent factors associated with CI. No formal education, slow gait time and institutionalization increased the risk of CI in both sexes. While education had a stronger effect in women, institutionalization had a stronger effect in men. Financial dependency, lack of exercise and incident stroke played a significant role in women.
An estimate of long-term care needs and identification of risk factors for institutionalization among Hong Kong Chinese aged 70 years and over.
BACKGROUND: The goal of this study is to estimate the long-term care needs of the Hong Kong Chinese population age 70 years and older, and to identify risk factors for institutionalization. METHODS: A three-year prospective follow-up study was carried out in Hong Kong Special Administrative Region, China. 2,032 subjects aged 70 years and older were recruited territory-wide by stratified random sampling of the Old Age and Disability Allowance register, covering over 90% of the elderly population. A questionnaire was administered at baseline to obtain information on social, functional, physical, and mental health status, and place of residence. A repeat interview was carried out at 36 months. The number of subjects moving from home to institution or vice versa, and the number who had died, were noted. Univariate analysis was performed to determine risk factors for institutionalization, and backward stepwise multiple logistic regression was used to identify independent factors predisposing to institutionalization. RESULTS: The institutionalization rate per year is estimated to be 0.7% for the 70-79 age group, and 1.5% for the 80+ age group. Using population figures projected by the Hong Kong Census, the corresponding number of places required will be 24,150 and 42,000, respectively, for the two age groups by 2005, whereas the number of government subvented places projected to be available is unlikely to be more than 40,000 for the whole population. Age, being a woman, being single, not having a formal education, cognitive impairment, physical dependency, and the presence of depressive symptoms were factors predisposing to institutionalization. In multivariate analysis, age, marital status, and dependency were identified as independent factors. CONCLUSION: The requirement for institutional places is unlikely to be met by government, the shortfall likely to be met by the private sector. Maintenance of functional independence, good social support network, engagement in social activities, and good informal carer support may reduce demand for institutional care.
The influence of income on morbidity, mortality and dependency in elderly Hong Kong Chinese.
The association between income and mortality, morbidity and dependency is examined in a 3-year prospective follow-up study of 2032 subjects aged 70 years and above in the Hong Kong Special Administrative Region, China. Subjects were recruited using stratified disproportional random sampling of the Old Age and Disability Allowance Schemes, covering over 90% of the population. Subjects were interviewed at baseline and after 36 months. Presence or absence of disease was based on self-report of doctor diagnosis together with a check of medication taken. Functional status was measured using the Barthel Index. For the disease analysis, subjects with the disease being analyzed at baseline were excluded; similarly for the dependency analysis, subjects who were dependent at baseline were excluded. Chi-square test, univariate and multiple logistic regression were used to examine the association between income and mortality, development of new disease, and dependency. There was no association between income and mortality, or with development of new disease. Development of dependency was associated with lower income at baseline. An income of less than 1000 HK dollars per month increased the risk of dependency by 1.8-fold (95%CI 1.1-2.9). However, this association disappeared after adjustment for age and sex. Absolute income is not an important factor contributing to mortality, morbidity and dependency in elderly Chinese aged 70 years and above. A freely accessible health and social service at low or no cost, the survivor effect, or other factors may account for the lack of association with income, contrary to findings from studies of whole populations worldwide. Therefore manipulating income alone is unlikely to affect these outcomes in the elderly.
Diluted venous blood appears arterial: implications for central venous cannulation.
IMPLICATIONS: There is always a danger of arterial puncture during central venous access. One can usually identify an inadvertent arterial puncture when the aspirated blood is bright red. This sign is removed if one were to put saline in the aspirating syringe, as dusky venous blood turns bright red on dilution.
Ten-year trends in CD4 cell counts at HIV and AIDS diagnosis in a London HIV clinic.
OBJECTIVE: To examine temporal trends (1986-1996) in the CD4 cell count at first HIV-1 positive test and initial AIDS diagnosis, and the influence of selected patient characteristics and treatment factors on these trends. DESIGN: A retrospective clinic-based study. SETTING: Three hospital-based clinics in West London. PATIENTS: A group of 5921 adult HIV-1-seropositive persons and 2835 reported patients with AIDS over a 10-year period from 1 January 1986 to 1 October 1996. METHODS: The CD4 cell count at HIV diagnosis (CD4HIV) was defined as the nearest CD4 cell count to within 2 months of HIV diagnosis; and the CD4 cell count at AIDS diagnosis (CD4AIDS) as the last CD4 cell count in the two months prior to the development of AIDS. Simple and multiple linear regression analysis were used to examine the influence of selected covariates on CD4HIV and CD4AIDS. RESULTS: The percentage of patients with an available CD4HIV and CD4AIDS increased from less than 5% in 1987 to 53% and 40%, respectively, in 1990, and 79% and 48%, respectively, in 1996. Patients with a missing CD4HIV or CD4AIDS were younger and less likely to have received antiretroviral therapy or prophylaxis for Pneumocystis carinii pneumonia (PCP). There was no significant change in CD4HIV over a 10-year period (median 334 x 10(6) cells/l), but a lower CD4HIV was associated with older age at presentation and injecting drug use. There was a delay in the onset of clinical AIDS, with a fall in the median CD4AIDS value from 99 x 10(6) cells/l prior to 1987, to 58 x 10(6) cells/l in 1990, 68 x 10(6) cells/l in 1994 and 60 x 10(6) cells/l in 1996; this decline in onset was seen for PCP as well as for cytomegalovirus and atypical mycobacterial infections. At all time periods, a lower CD4AIDS was associated with combined use of antiretroviral therapy and PCP prophylaxis. After adjustment for use of antiretroviral therapy and PCP prophylaxis prior to AIDS diagnosis, year of diagnosis was no longer associated with CD4AIDS. There was a significant trend towards an improved survival following AIDS diagnosis from 20.1 months prior to 1988, to 20.3 months (1989-1990), 21.0 months (1991-1992) and 22.1 (1993-1994) (P < 0.0005). CONCLUSIONS: The observed decline in CD4AIDS value was related to the introduction of antiretroviral therapy in 1988, and PCP prophylaxis in 1989. Temporal changes in the CD4 cell count at HIV and AIDS diagnosis among different demographic groups can provide insights into the changing natural history of the HIV epidemic and access to medical care. We recommend monitoring of the CD4 cell count at new HIV and AIDS diagnosis and at initiation of antiretroviral therapy as additional measures in national HIV/AIDS surveillance.
Walking speed and stride length predicts 36 months dependency, mortality, and institutionalization in Chinese aged 70 and older.
BACKGROUND: Increasing emphasis is being placed on physical performance measures as an outcome predictor. It is uncertain whether one or two simple measurements will have predictive value compared with a battery of tests. OBJECTIVES: To assess whether simple performance measures such as walking speed and stride length will predict dependency, mortality, and institutionalization. DESIGN: A 3-year longitudinal study of a random sample of subjects. SETTING: Older people living in the community in Hong Kong, Special Administrative Region, China. SUBJECTS: A total of 2032 Chinese subjects aged 70 years and older were recruited territory-wide by proportional random sampling and followed for 3 years. MEASUREMENTS: Functional status was measured using the Barthel Index at baseline and follow-up. The time taken to walk a distance of 16 feet and the number of steps taken were measured at baseline. Stride length is estimated by dividing 16 by the average number of steps needed to complete the walk. Outcomes regarding dependency, mortality, and institutionalization at 36 months were recorded. RESULTS: After excluding subjects lost to follow-up and those who had died, data were available for 559 men and 612 women. Univariate analysis showed that reduced walking speed and stride length were associated with increased risk of dependency, mortality, and institutionalization. In multivariate analysis for dependency and mortality, stride length, walking speed, age, and sex were included in the best prediction model (ROC = 0.798 and 0.707, respectively), whereas only stride length was included in the prediction for institutionalization (ROC = 0.764). CONCLUSIONS: In terms of prevention or modifying outcomes, these two simple performance measures may be used as indicators for checking for occult disease and for interventional measures such as exercise prescription.
Use of color Doppler EUS in assessing azygos blood flow for patients with portal hypertension.
BACKGROUND: Azygos blood flow is an index of blood flow through gastroesophageal collateral vessels and varices in portal hypertension. Conventional measurement of azygos blood flow involves catheterization of the azygos vein. We studied the feasibility of assessing azygos blood flow with color Doppler endosonography and of monitoring the effects of vasoactive agents on azygos blood flow. METHODS: Patients with portal hypertension were examined by means of linear array color Doppler endoscopic ultrasonography (EUS). Patients who had taken propranolol or nitrates in the 4 weeks before the day of measurement of azygos blood flow were excluded. After identification of the azygos vein and recording of baseline readings of mean arterial blood pressure, pulse rate, and azygos blood flow, patients were selected in a random manner to receive a bolus injection of 2 mg terlipressin, 250 microg somatostatin, or saline solution (control). Azygos blood flow was measured 1, 5, and 10 minutes after injection (AzBF-1, AzBF-5, AzBF-10). RESULTS: Six patients were recruited in each treatment group. Basal azygos blood flow showed a positive association with the Child-Pugh grade of cirrhosis (p < 0.005). After bolus injection of terlipressin and somatostatin, there was a marked decrease in AzBF-1 (24% and 37%), AzBF-5 (42% and 19%), and AzBF-10 (40% both) compared with baseline. The control group showed no significant change in azygos blood flow. CONCLUSIONS: Color Doppler EUS is useful in assessing azygos blood flow in portal hypertension and in monitoring the effects of vasoactive agents.
Are HIV-infected patients with rapid CD4 cell decline a subgroup who benefit from early antiretroviral therapy?
We have developed a model to determine whether asymptomatic HIV-infected individuals who have a rapid CD4 cell decline are a subgroup who might benefit from early antiretroviral therapy. Data were obtained from a subgroup of participants in the Concorde and EACG020 trials, two randomized, double-blind, comparative trials of immediate (IMM) versus deferred (DEF) zidovudine therapy in asymptomatic HIV-infected individuals. The subgroup comprised 297 patients (IMM = 154, DEF = 143) who had at least one CD4 cell count before and after randomization. The median CD4 cell count at randomization was 491 x 10(6)/L, and the median follow-up was 61 months. The rate of CD4 decline before and after randomization was estimated using multi-level linear regression analysis, and patients were stratified into quartiles according to the rate of CD4 cell decline before randomization. Outcome measures were the development of AIDS, a 50% drop in CD4 count from the baseline, and death. A Cox proportional hazards model was used to examine whether the effect of zidovudine on disease progression varied according to the previous rate of CD4 decline. We found that a more rapid rate of CD4 decline before randomization was associated with a greater reduction in the rate of CD4 decline following IMM antiretroviral therapy (r = -0.5, P = 0.03). The greatest risk reduction in disease progression with IMM antiretroviral therapy was seen in the quartile of patients with the highest rate of CD4 decline (> or = 26 x 10(6) cells/L per 6 months) (hazards ratio (HR) = 0.61, 95% CI = 0.35-1.05). However, this effect was statistically significant in only the Concorde trial (HR = 0.48, 95% CI = 0.29-0.89). In contrast, we found no evidence in the EACG020 trial of any trend towards greater benefit in those with the most rapid CD4 cell decline. These findings suggest that asymptomatic patients with rapid CD4 cell decline are a subgroup likely to benefit from early antiretroviral therapy. This analytic approach should now be replicated in trials of combination therapy, and these should include viral load data.
Body composition in Chinese subjects: relationship with age and disease.
Body composition measurement by dual energy absorptiometry was carried out in 160 men (age 45-87 years) and 407 women (age 20-88 years) consisting of volunteers and 25 men and 14 women with chronic obstructive airways disease (COAD) not receiving steroids from a hospital respiratory clinic. The objectives of this study were to provide normal reference values for adult Chinese including the elderly; to examine the effect of age and COAD on body composition; and to compare the use of body mass index (BMI) as a measure of obesity or malnutrition compared with body composition measurements. Values for body composition were different when compared with studies in the Caucasian population. In both sexes, height and lean mass decreased in a linear fashion with aging. In men, total body water increased till the 55-65 age group and then decreased. In women, total body water and bone mineral content also decreased with aging in a linear fashion. Changes in weight, BMI, fat mass and percentage fat with aging were also present in women and followed a quadratic trend. BMI was not a sensitive index of obesity or undernutrition, having approximately only 50-60% sensitivity in detecting high percentage fat or low standardised lean mass values. COAD was associated with low BMI only. Body composition measurements changes with aging, and should be used instead of BMI as a better indication of obesity or undernutrition. Reference values derived from the appropriate ethnic group should be used.
Cardiovascular risk factors and 18-month mortality and morbidity in an elderly Chinese population aged 70 years and over.
OBJECTIVE: To determine the influence of some cardiovascular risk factors (hypertension, diabetes mellitus, smoking habit, physical activity, obesity, adverse lipid profile) in elderly Chinese aged 70 years and over, on overall mortality and morbidity from stroke and ischaemic heart disease. DESIGN: Longitudinal study relating 18-month outcome to baseline values. SUBJECTS: 2,032 subjects (999 men, 1,033 women), mean age 80 years, recruited by random sampling of the Old Age and Disability Allowance Schemes, which covers 90% of the Hong Kong elderly subjects, stratified by sex and 5-year age groups from 70 years onwards. METHODS: At baseline, subjects were visited by interviewers to collect information regarding medical conditions, smoking habit, physical activity, and to measure their height, weight, skinfold thickness, and waist/hip ratio. A follow-up survey was carried out 18 months later to establish the development of any new stroke or ischaemic heart disease, and to note any deaths and the cause of such deaths from death certification. RESULTS: In multivariate analysis overall mortality was negatively associated with body mass index and participation in physical activity, after adjusting for age and sex. Death from stroke was associated with a higher systolic blood pressure at baseline. Among survivors, the only significant associations observed were a negative association between body mass index and the development of heart disease, and a positive association between systolic blood pressure and development of stroke. CONCLUSIONS: Few associations between cardiovascular risk factors and morbidity and mortality were demonstrated in elderly Chinese with a mean age of 80 years. The only modifiable risk factor appears to be systolic blood pressure.
Impact of chronic diseases on functional limitations in elderly Chinese aged 70 years and over: a cross-sectional and longitudinal survey.
OBJECTIVE: To examine the association of some common medical conditions with functional limitation in elderly Chinese aged 70 years and over, to estimate the percentage of disability attributable to individual diseases, and to attempt to identify predisposing factors by documenting the development of functional limitation over an 18-month period in those subjects with a particular disease who were independent initially. SUBJECTS AND METHODS: The cross-sectional data set consisted of 2,032 (999 M, 1,033 F) subjects aged 70 years and over recruited by random sampling (stratified by age and sex) of all recipients of old-age and disability allowance, which covers over 90% of the elderly population. Information regarding medical condition and functional assessment of ten basic activities of daily living using the Barthel Index were obtained by personal interviews and physical assessment of the respondents at their places of residence. The longitudinal data set consisted of 1,334 subjects with no functional limitation at baseline who were alive after 18 months. Functional status was reassessed. RESULTS: After adjusting for age and sex, diseases associated with severe functional limitation (Barthel Index < 15) were dementia, stroke, Parkinson's disease, and fractures. Those associated with mild to moderate functional limitation (Barthel Index 15-19) were the same, with the addition of asthma and diabetes mellitus. The attributable fraction for severe limitation was highest for stroke, dementia, and fractures. Stroke and arthritis were identified as diseases predisposing to mild to moderate functional limitation over an 18-month period among those subjects who were independent initially. CONCLUSION: Stroke, dementia, and fractures were the main chronic diseases associated with severe functional limitation in elderly Hong Kong Chinese. Attempts to reduce the disability burden in this population should target these diseases.
Red cell age and susceptibility to malaria during pregnancy.
BACKGROUND: Increased susceptibility to malaria in pregnancy is well recognized, and has generally been assumed to be due to hormonal changes resulting in altered immunity. Based on previous work demonstrating enhanced parasite growth in young normal and thalassemic red blood cells, we hypothesized that in pregnancy increased malaria susceptibility may be due, in part, to the increase in the population of young red cells. METHODS: FC27 strain of Plasmodium falciparum was cultured in the red cells and sera from healthy primigravida pregnant (n=9) and non-pregnant (n=9) women. Red cells from both pregnant and non-pregnant women were each placed in three cultures containing the sera from pregnant, non-pregnant and pooled control samples. Cultures were set up in triplicate and incubated for 144 hours. Parasite development and growth were assessed by slide microscopy. RESULTS: At 96 hours the median parasite growth in cells from pregnant samples (5.7%) was significantly better than that in the non-pregnant cells (4.8%) (p=0.01). There was no significant difference in parasite growth in cultures with pregnant and non-pregnant sera. As expected, there were significant differences in parameters measuring red cell age between the cells from pregnant and nonpregnant samples: median red cell creatine (11.09 mg/dl) versus (6.90 mg/dl) (p=0.004) and median reticulocyte count (2.3%) versus (1.4%) (p=0.0006). CONCLUSIONS: These preliminary results are consistent with the hypothesis that an increased population of young red cells may contribute to increased malaria susceptibility during pregnancy.
Postconcussion syndrome following mild head injury: how significant when it is work-related?
Postconcussional complaints are common after mild head injury. These symptoms can be so severe that some patients are unable to return to their previous employment. The purpose of this study is to investigate how important is work-related injury as a factor in determining the degree of disability caused by postconcussional symptoms. We studied 67 patients suffering from postconcussion syndrome after a mild head injury. These patients were divided into two groups, work-related injury and non-work-related injury. The results of this study demonstrated that the median duration of sick leave and the median amount of compensation were significantly higher in the work-related group (8 months vs. 1 month, P = 0.0007; US$9000 vs. US$500, P = 0.0035, respectively). Only 41% of the work-related injured patients returned to work, compared with 85.7% in the nonwork-related injury group (P = 0.0022). The results of this study strongly suggested that work-related injury is a significant factor in determining the degree of disability associated with postconcussion syndrome.
Relationship between CD4 count and CD4% in HIV-infected people.
OBJECTIVE: To describe the relationship between absolute CD4 count and CD4%, and the influence on this of gender, risk group, age, a diagnosis of AIDS, use of zidovudine (ZDV) therapy and PCP prophylaxis. METHODS: 9203 paired serial measurements of CD4 count and CD4% on 1017 initially AIDS-free and ZDV-naive HIV positive patients from a London-based cohort were available for analysis. Multi-level regression procedures were used on log-transformed data to relate values of CD4 count to a given level of CD4%. We estimated the effect of selected covariates on this relationship from the exponent of the covariate coefficient. RESULTS: A strong linear relationship was found between log CD4 and log CD4%, CD4 = e 1.78(CD4%)1.26 or 5.93 (CD4%)1.26 (excluding covariates). Based on this model, a CD4% of 5%, 15%, and 30% corresponded to an estimated CD4 count (95% confidence interval [CI]) of 45 cells/mm3 (17-117 cells/mm3), 182 cells/mm3 (64-499 cells/mm3) and 438 cells/mm3 (132-1395 cells/mm3), respectively. However, after adjustment for selected covariates, the predicted CD4 count for a given CD4% was found to be lower among heterosexuals and injecting drug users as compared with homosexual men by 30% and 17% respectively; following an AIDS diagnosis by 21%; and after initiation of ZDV therapy and PCP prophylaxis by 19% and 10%, respectively. CONCLUSION: This analysis should be useful to clinicians and researchers in relating values of CD4 count to CD4%, although we have demonstrated that this is not a simple relationship. The wide CI observed in the estimated CD4 count particularly at high CD4% values, and the adjustments necessary according to risk group, following an AIDS diagnosis and use of ZDV and PCP therapy limit its application in the clinical setting.
Prevalence and effectiveness of treatment of hypertension on cardiovascular morbidity and mortality in an elderly population aged 70 years and over.
The prevalence of hypertension, effectiveness of blood pressure control and compliance, and the effectiveness of treatment on 18-month overall mortality and development of cardiovascular disease in an elderly Chinese population were studied. The study group examined were aged 70 years and over, and consisted of a random sample of subjects on the Old Age and Disability Allowance register. They were stratified by sex and 5-year age groups from 70-74 to 90+ years. Information obtained at baseline included medical history, use of drugs, and measurement of blood pressure. Subjects with a blood pressure > 160/90 were classified as hypertensive. The overall prevalence of hypertension was 48%, 19% being undiagnosed. Among subjects with a known history of hypertension and taking drugs, only approximately half had adequate control (BP < or = 160/90). One fifth of those with a known diagnosis of hypertension were not taking drugs. Subjects who developed stroke had a higher mean systolic and pulse pressure at baseline; no difference in mean pressures was observed for overall mortality or development of heart disease. No difference in mortality or development of cardiovascular disease was observed between the following groups: known history of hypertension and taking medication with controlled blood pressure, known history and taking medication and blood pressure poorly controlled or not taking drugs, and normal blood pressure with no history of hypertension.
An estimate of chronic disease burden and some economic consequences among the elderly Hong Kong population.
OBJECTIVES: To estimate the burden of chronic disease for an elderly Chinese population aged 70 years and over, and to illustrate the use of this information in estimating the economic consequences of disease burden using stroke as an example. PARTICIPANTS: A total of 1902 subjects recruited by random sampling of the old age and disability allowance schemes, which cover over 90% of the Hong Kong elderly population, stratified by sex and five year age groups from age 70 years onwards. METHOD: Information was collected on 10 medical conditions at baseline: arthritis, hypertension, cardiac disease, stroke, chronic obstructive airways disease, peptic ulcer, diabetes mellitus, osteoporotic fracture, malignancy, and dementia. A follow up survey was carried out after 18 months to determine the occurrence of new disease and the number with disease who had died. Disease burden is calculated as the number with disease at baseline plus the number developing new disease minus the number who had died. RESULTS: Disease burden figures were highest for arthritis, hypertension, cardiac disease, and peptic ulcer, and were higher in the 70-79 age group than the 80+ age group for some diseases. For stroke, the economic cost based on a population projection for 2001 was estimated to be around HK$1,900,000,000, or US$250 million. CONCLUSION: Information on the burden of chronic disease is important. It enables the economic consequences to be estimated so that strategies can be developed to prevent diseases with high costs and known effective preventive methods.
Invasion and growth of Plasmodium falciparum is inhibited in fractionated thalassaemic erythrocytes.
Epidemiological and clinical studies have indicated that the thalassaemias may confer protection against malaria. The study reported here investigated this protective effect in vitro, using a new approach which controls for the potential effect of red cell size and age on the virulence of the parasite. A Percoll density gradient method was used to separate alpha- and beta-thalassaemic trait, haemoglobin H and normal red blood cells (RBC) into fractions of different density. Correlations between RBC density, age and size in fractions of all genotypes were established using red cell creatine as an index of cell age. The development of Plasmodium falciparum over 3 erythrocytic cycles (144 h) in whole blood as well as fractionated samples was monitored by slide microscopy and flow cytometry. A significantly reduced rate of parasite invasion and growth was demonstrated in RBC from all thalassaemic genotypes tested. Poor reinvasion rates were noted in the second and third cycles. Increased duration of culture and red cell age also had a greater negative impact on parasite growth in thalassaemic RBC. This poor growth rate was also associated with the arrest of parasite growth at the schizont stage (schizont maturation arrest) and the accumulation of abnormal, trophozoite/schizont stage parasites in the older thalassaemic RBC fractions. These findings suggest a defect in the number and viability of merozoites generated by parasites growing in thalassaemic RBC. Age related factors such as oxidant stress may play a key role in mediating this kind of protective mechanism and deserve further investigation.
The time course and regional variations of lipid peroxidation after diffuse brain injury in rats.
Free radicals are generated after head injury. These radicals rapidly react with polyunsaturated fatty acids in the cell membrane and cause membrane destruction. This process is called lipid peroxidation. Malondialdehyde (MDA) is one of the end products of lipid peroxidation, and it is a frequently used indicator of lipid peroxidation in biological tissues. Using a diffuse head injury animal model, we studied the time course of lipid peroxidation in different regions of injured rat brains. In the present study, the MDA levels were 36.7%, 41.8%, and 35.1% greater than sham at one hour after injury at the frontal, parietal, and brain stem, respectively (p < 0.0001). The MDA levels in these regions continued to increase and peaked a 4 hours after the injury. The levels slowly decreased, and by 24 hours, they were still significantly higher than the sham control's. The elevation of MDA levels was less in the striatum and the temporal regions at one hour. They were 16.9% and 13.3%, respectively (p < 0.002). The MDA levels in these two regions continued to increase even after 4 hours of injury, but the degree of elevation never exceeded 35%. The results demonstrate that there is an immediate, posttraumatic burst of MDA production, suggesting the formation of free radicals after diffuse head injury. Even though all the regions sampled show the same effect, certain regions are less affected by this diffuse head injury animal model.
An estimation of the functional disability burden in elderly Chinese age 70 years and over.
A cross-sectional survey of functional status among elderly Hong Kong Chinese aged 70 years and over was carried out to estimate the current burden of disability. Two thousand and thirty-two subjects (999 men, 1033 women) were recruited by random sampling of the old age and disability allowance schemes covering over 90% of the elderly population, stratified by sex and 5-year age groups. Functional ability was administered using the Barthel Index. The duration of disability, if any, was also noted. The prevalence of disability for different activities of daily living varied from 0.8% to 26% (lowest for feeding and highest for climbing stairs and bathing). The prevalence was higher for women than men, and higher in the older age group for both sexes. Men in the 80+ age group had shorter duration of disability compared with those in the 70-79 age group, and compared with women. Using disability years (estimated number of elderly with disability in the population x median duration of disability) as an estimate of disability burden, the number ranges from approximately 19,000 (inability to feed) to 100,000 (inability to climb stairs). This estimate may be useful in the planning of service provisions for the formal and informal care sector.