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Biomedical subjects

H Chiu

Publications and source records attributed to H Chiu.

At least 37 records · Page 2Linked to original sources
PubMed1996

Apolipoprotein E genotype and Alzheimer's disease in Hong Kong elderly Chinese.

We studied the apolipoprotein E (apoE) allele frequencies in 65 Chinese patients with late-onset Alzheimer's disease (AD) and 82 age- and sex-matched controls. The apoE epsilon 4 allele frequency was significantly higher in the AD group than in the control group (0.169 versus, p < 0.01). There were five homozygotes for epsilon 4 in the AD group but none among the controls. The odds ratio for AD was 1.6 for epsilon 4 heterozygotes. The age at onset was lower in the presence of the epsilon 4 allele and higher with the epsilon 2 allele, although neither of these differences reached statistical significance. The association between apoE alleles and AD previously reported in Caucasian populations was also present in this reports of lower prevalence of AD compared with the prevalence of multi-infarct dementia.

Aged↗
PubMed1995

An audit study of defaulters of regular psychiatric outpatient appointments in Hong Kong.

This paper describes an audit study of general psychiatric outpatient defaulters in Hong Kong. Defaulters were increased among those who were married, unemployed, housewives, seen within one year, receiving medications and previously admitted to hospital. Clinical diagnoses (ICD-10 Axis-1) of the F1, F2, F3 and F7 groups were also associated with increased defaulting behaviour. However, fewer defaulters were found among those who were aged below 19, single, employed, students, and had diagnostic groups of F4 and F9. These results added new information on the non-attendance behavioral pattern of Chinese patients.

Adolescent↗
PubMed1994

Regulation of the avidity of integrin alpha 4 beta 7 by the beta 7 cytoplasmic domain.

Integrins are cell-surface heterodimeric receptors with adhesive and transmembrane signaling properties. Their cytoplasmic domains can affect receptor avidity, cytoskeletal association, and post-receptor occupancy events. The alpha 4 beta 7 integrin mediates cell adhesion to Peyer's patch high walled endothelial venules (HEV), VCAM, and CS-1/fibronectin. To determine the role of the beta 7 cytoplasmic domain in these interactions, wild-type and truncated beta 7 subunits were stably expressed in the alpha 4+/beta 1-/beta 7- B cell lymphoma 38C13. The cell line delta 727 lacks the entire beta 7 cytoplasmic domain, delta 753 lacks the 34 C-terminal residues, and LXSN is vector-transfected 38C13. Cells expressing wild-type beta 7 bound Peyer's patch HEV, fibronectin, and immobilized VCAM constitutively and did not require prior activation with phorbol esters. Interestingly, delta 753 displayed no ligand binding activity, while delta 727 was constitutively active for all ligands and displayed greater avidity for fibronectin and Peyer's patch HEV than the wild-type beta 7. beta 7, delta 753, delta 727, and LXSN were also tested for the ability to bind soluble VCAM in the presence of various divalent cations. In the presence of Ca2+, but not Mg2+, delta 727 constitutively bound soluble VCAM, whereas beta 7, delta 753, and LXSN did not. beta 7 and delta 753 could bind soluble VCAM if first activated with Mn2+. The results suggest that: (i) alpha 4 beta 7 can be expressed in a constitutively active state, (ii) the beta 7 cytoplasmic domain regulates the avidity of alpha 4 beta 7, and (iii) 38C13 cell lines expressing wild-type and truncated beta 7 subunits define three stable activation states of alpha 4 beta 7: inactive (delta 753), partially active (beta 7), and fully active (delta 727) receptors.

Amino Acid Sequence↗
PubMed1994

The prevalence of depressive symptoms and predisposing factors in an elderly Chinese population.

In a survey of elderly Chinese aged 70 years and over living in Hong Kong selected by stratified random sampling, the prevalence of depression was determined using the 15-item Geriatric Depression Scale using a cut-off point of 8 (sensitivity 96.3% and specificity 87.5% for this population). Subjects with moderate to severe cognitive impairment (CAPE I/O score < or = 7) were excluded. There were 877 men and 734 women. The adjusted overall prevalence for this population was 29.2% for men and 41.1% for women. The prevalence increased with age in men and was higher in women than in men. Univariate analysis identified many factors in the following areas that were associated with depression: socioeconomic characteristics, functional ability, physical health and social support. Stepwise logistic regression identified 16 factors predictive of depression: socioeconomic characteristics, such as borderline living expenses and dissatisfaction with living arrangement; poor social support, such as absence of an informal carer when ill, few relatives to turn to, and infrequent contact with neighbours and friends; functional disability, as indicated by a Barthel Index < 15, urinary incontinence and inability to do housework; and poor physical health--poor self perceived health, poor vision, difficulty with chewing, history of mental illness, frequent hospital admissions and increased level of symptoms such as poor memory, constipation and dizziness. Some of these factors may be amenable to intervention, and such measures may be important in reducing the high prevalence of depression in elderly people.

Aged↗
PubMed1993

Biosynthesis and function of membrane bound and secreted forms of recombinant CD11b/CD18 (Mac-1).

Full-length (membrane bound) and truncated (secreted) forms of the beta 2 integrin heterodimer, CD11b/CD18 (Mac-1), were expressed in a human kidney cell line (293) that normally does not express leukocyte adhesion molecules (Leu-CAMs). The biosynthesis of recombinant Mac-1 in 293 cells differed from that reported for leukocytes in that heterodimer formation was not required for CD11b to be exported to the cell surface. A stable cell line was constructed that constitutively secreted the recombinant, truncated Mac-1 heterodimer into growth conditioned cell culture medium. A novel monoclonal antibody that enabled an immunoaffinity method for the selective purification of recombinant Mac-1 heterodimers was identified. Sufficient protein was purified to allow the first measurement of the 50% inhibitory concentration (IC50) for CD11b/CD18 and for the direct comparison of the inhibitory activity of recombinant soluble Mac-1 with that of various CD18 and CD11b specific monoclonal antibodies. Purified recombinant soluble Mac-1 inhibited the binding of neutrophils, activated by opsonized zymosan or fMet-Leu-Phe peptide, to human umbilical vein endothelial cells. Similarly, the recombinant integrin was effective in inhibiting the binding of unactivated neutrophils to tumor necrosis factor (TNF-alpha) activated endothelial cells. The availability of an abundant source of purified, biologically active Mac-1 will enable direct physical and chemical investigations into the relationship between the structure and function of this leukocyte adhesion molecule.

Carbohydrates↗
PubMed1993

Evidence supporting a role for cathepsin B in the generation of T cell antigenic epitopes of human growth hormone.

The elucidation of the enzymatic processing mechanism associated with the formation of antigenic peptide fragments that combine with MHC class II molecules is fundamental to our understanding of the immune system. We have investigated a structurally well defined protein, recombinant human growth hormone (rhGH), as an antigen, and present data supporting the hypothesis that the enzyme cathepsin B can produce peptide fragments bearing T cell epitopes associated with lymphocyte proliferative response to hGH in Balb/c (H-2dhaplotype) mice. Minimal T cell epitopes are not generated; rather the cathepsin cleavage sites flank the three antigenic peptide regions, amino acid residues 31-41, 81-100, and 166-181.

Amino Acid Sequence↗
PubMed1993

Association of negative symptoms with tardive dyskinesia in schizophrenic patients.

In recent years, a great deal of interest has been focused on the association between negative symptoms of schizophrenia and tardive dyskinesia, but the literature is far from conclusive. Thirty-six schizophrenic patients with tardive dyskinesia and 76 without were surveyed using the Scale for Assessment of Negative Symptoms. On univariate analysis, the composite score and scores of certain subscales were associated with tardive dyskinesia, but this association was lost on multivariate analysis. After adjusting for confounding variables like age, education and antipsychotic dose, no association of negative symptoms and tardive dyskinesia was found.

Adult↗
PubMed1992

Prevalence of tardive dyskinesia, tardive dystonia, and respiratory dyskinesia among Chinese psychiatric patients in Hong Kong.

OBJECTIVE: Only scanty information on the prevalence of tardive dyskinesia in Chinese patients has been available. This study was undertaken to examine the prevalence of tardive dyskinesia, tardive dystonia, and respiratory dyskinesia in Chinese psychiatric patients in Hong Kong. METHOD: All inpatients of a mental hospital in Hong Kong, except those in the admission and children's wards, were surveyed with the Abnormal Involuntary Movement Scale, and standard research criteria were used to establish the diagnosis of tardive dyskinesia. In addition, patients were screened for tardive dystonia, according to published criteria, and for respiratory dyskinesia by physical examination and laboratory tests. RESULTS: Among the 917 patients surveyed, the prevalence rates were 9.3% for tardive dyskinesia, 0.4% for tardive dystonia, and 1.2% for respiratory dyskinesia. With multivariate analysis, greater age and a lower current dose of antipsychotic, but not the presence of mood disorder, were factors found to be significantly associated with tardive dyskinesia. CONCLUSIONS: The prevalence rates were much lower than those found in Western studies. This may indicate that there is an ethnic difference in the prevalence of these conditions. Prospective cross-cultural studies are necessary to explore this possibility.

Adolescent↗
PubMed1992

Neuroleptic prescription for Chinese schizophrenics in Hong Kong.

There are very few studies on the pattern of neuroleptic prescription for schizophrenics in Asia. 106 schizophrenic patients in a psychiatric unit of a general teaching hospital in Hong Kong were surveyed. The mean daily dose (in chlorpromazine equivalent) was low (568.5mg). The mean daily dose of high potency agents was four times that of low potency agents. A high frequency of use of anticholinergic drugs may indicate that Chinese are more susceptible to acute extrapyramidal side-effects.

Adult↗
PubMed1992

Studies on efficacy and stability of a vaccine bait containing ERA strain of rabies virus propagated in a BHK-21 cell line.

In a dose response study in foxes, the median protective dose of ERA BHK21 vaccine in a blister pack bait was 10(6.0) tissue culture infective doses (TCID)/mL, while artificially aged baits with titers of 10(6.3) TCID/mL induced seroconversion in 78% of foxes. There was no significant difference in the development of antibodies in foxes receiving 1, 2 or 3 mL volumes of vaccine in the bait. When baits were exposed to the elements and fed to foxes over a 21 day period, 85% of the animals seroconverted. Age, sex and the way in which the vaccine container was contacted did not appear to be factors in the responses of these animals. Juvenile foxes, approximately six months of age, were marked more readily with the tetracycline bait marker than older animals. Approximately 25% of foxes did not appear to respond well to vaccination and the titer of the vaccine was a critical factor in producing seroconversion in these animals.

Age Factors↗
PubMed1990

Sleep apnoea presenting as severe hypertension and silent occipital haemorrhage.

A 39-year old Chinese man presented with an acute onset of severe headache, accelerated hypertension and subsequently an unexpected extensive right occipital haemorrhage. These were found to be related to a sleep apnoea syndrome which had been unrecognized for many years despite its typical symptoms of loud snoring and excessive daytime sleepiness. Weight reduction led to significant clinical but not polysomnographic improvement of the sleep apnoea syndrome.

Adult↗
PubMed1984

Modulation by a human interferon of antitumor effects of cyclophosphamide against a lymphosarcoma in hamsters.

Administration to hamsters of a highly purified human leukocyte interferon subtype, IFN-alpha A, obtained by recombinant DNA methods, abolished the efficacy of high doses of cyclophosphamide (2.5 mg/hamster) against the TBD 932 lymphosarcoma. The effect was more pronounced with concomitant than with sequential treatments and did not occur with melphalan. Antagonistic effects occurred at high interferon doses (10(5) I.U./treatment), but an additive or synergistic positive effect occurred at lower interferon doses (10(3) I.U./treatment) and at lower, non-protective, doses of cyclophosphamide. These effects may be due to immunomodulatory responses induced by the drugs involved.

Animals↗
PubMed1984

The synergistic anti-proliferative effect of gamma-interferon and human lymphotoxin.

Highly purified preparations of rHuIFN-gamma and HLT synergistically inhibit the in vitro proliferation of WI38VA13 cells, a SV40 virus-transformed derivative of the human cell line W138. The growth of nontumorigenic WI38 cells, established from normal diploid embryonic lung tissue, was not inhibited under identical incubation conditions; rMuIFN-gamma and HLT have the same in vitro effects on the murine melanoma B16. Thus, the combination of rMuIFN-gamma and HLT synergistically inhibits the growth of B16 cells, although incubation with either lymphokine alone has no significant anti-proliferative effect. Flow cytometric analysis of the cell cycle of asynchronous cells indicates that when B16 melanoma cells are treated with rMuIFN-gamma and HLT in combination, more cells accumulate in the G0/G1 phase than when the cells are treated with rMuIFN-gamma alone. It appears that populations of rapidly proliferating tumor cells, which normally contain a large percentage in the S+G2+M phases of the cell cycle, become arrested in the quiescent G0/G1 phase by the combination of IFN-gamma and HLT, resulting in the inhibition of cell growth.

Animals↗
PubMed1983

Importance of treatment regimen of interferon as an antitumor agent.

A highly purified hybrid human leukocyte interferon, IFN-alpha AD, produced in Escherichia coli, has been used to define optimum treatment conditions for L1210 leukemia in mice. Treatments prior to tumor inoculation were ineffective. Treatments from the third day post-tumor inoculation were most effective, and treatments every third day were more effective than were regimens involving more frequent treatments. IFN-alpha AD was effective in vivo against tumors formed from a line of L1210 cells resistant to IFN-alpha AD in cell cultures. These and other results indicate the importance and nature of indirect mechanisms of action for efficacy of interferons against tumors.

Animals↗
PubMed1982

Stimulation of natural killer cell activity and inhibition of proliferation of various leukemic cells by purified human leukocyte interferon subtypes.

One of several human leukocyte interferon subtypes A (LeIF-A), obtained in purified form from a gene cloned in Escherichia coli, stimulated human peripheral blood natural killer cell activity, whereas another human leukocyte interferon subtype D (LeIF-D) had no effect with the use of K562 as target cells. With Daudi as target cells, both LeIF-A and LeIF-D stimulated natural killer cell activity. A hybrid human leukocyte interferon, NH2-terminal 61 amino acids and COOH-terminal 104 residues of LeIF-A and LeIF-D, respectively (LeIF-AD) showed greater stimulation than did LeIF-A, but the stimulation did not exceed that of natural buffy coat interferon. A mixture of equal antiviral units of LeIF-A and LeIF-D was no more effective than was LeIF-A alone. The cloned interferon subtypes showed differential effects on the proliferation of three human leukemic cell lines: Daudi (B-cell lymphoblastoid leukemia); BALL 1 (B-cell acute lymphoblastic leukemia); CCRF-HSB-2 (T-cell acute lymphoblastoid leukemia). Growth of Daudi cells was generally most sensitive to all the interferons tested, LeIF-A, -D, -AD, and a buffy coat preparation; no viable cells remained after 120-hr exposure to 1000-unit/ml doses of the interferons. BALL 1 was relatively resistant to the interferon subtypes tested including LeIF-AD, but this cell lines was very sensitive to a preparation of natural buffy coat interferon. CCRF-HSB-2 showed some sensitivity to all the interferons with greatest sensitivity to LeIF-A (10% of the viable cells were detected after 1000 units/ml exposure for 120 hr). In contrast to the leukemic cell lines tested, human amnion cells (WISH) and the human erythroid leukemia, K562, were resistant to the antiproliferative activity of the interferons.

Cell Division↗