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Biomedical subjects

C F Chan

Publications and source records attributed to C F Chan.

15 recordsLinked to original sources
PubMed1997

Remanipulation of forearm fractures in children.

AIMS: To determine whether operator experience or time of operation affects the outcome of fractures of the forearm in the paediatric age group as measured by the need for remanipulation. METHODS: A retrospective analysis of 1155 children with forearm fractures requiring manipulation was undertaken. RESULTS: The remanipulation rate for these 1155 children was 136 or 11.7%. There was a significant difference in those fractures requiring remanipulation dependent upon the experience of the operator and the time of day the procedure was performed. The lowest rate of remanipulation was obtained by senior registrars operating between the hours of 0800-1700 (6/113 or 5.3%). The highest rate was found to be junior registrars between the hours of 1700-2200 (39/167 or 23.3%). It is especially interesting to note the relatively low rate (31/437 or 7.1%) obtained by junior registrars during the night shift (2200-0800 hours). CONCLUSIONS: The current overall remanipulation rate is acceptable. The low rate between 2200-0800 hours means rescheduling of these patients is unnecessary. The rate for junior registrars between 1700-2200 hours needs to be improved.

Adolescent↗
PubMed1996

Hyperhomocysteinaemia and premature coronary artery disease in the Chinese.

OBJECTIVES: To examine the prevalence of hyperhomocysteinaemia and compare it with the classic risk factors and vitamin status in Hong Kong Chinese patients with premature atherosclerotic coronary artery disease. DESIGN: Case-control study. SETTING: General hospital and community. SUBJECTS: Forty five patients (39 males) with significant coronary artery disease confirmed by angiography (32 post myocardial infarction) and 23 healthy volunteers (17 male), all aged less than 55 years. INTERVENTION: Standardised methionine-loading test. MAIN OUTCOME MEASURES: Coronary artery disease, risk factors. RESULTS: More patients than controls had fasting hyperhomocysteinaemia (10/45 v 2/23, P = 0.122), post-methionine hyperhomocysteinaemia (17/45 v 1/23, P = 0.008), and an abnormal response to methionine (15/45 v 1/23, P = 0.015). A history of smoking was more frequent in patients (3/23 v 25/45, P = 0.002). Sixteen of 17 patients with hyperhomocysteinaemia but only nine of 28 with normohomocysteinaemia were smokers (P = 0.0002). Fasting plasma cholesterol concentrations (mean (SD)) were higher in hyperhomocysteinaemic patients (6.41 (1.58) mmol/l) than in controls (5.53 (0.90) mmol/l) (P = 0.042). Serum vitamin B-12 was not reduced and serum folate was higher in hyperhomocysteinaemic patients (35 (4) nmol/l) than normohomocysteinaemic patients (26 (9) nmol/l) (P = 0.009). CONCLUSIONS: Although the prevalence of hyperhomocysteinaemia in Hong Kong Chinese is similar to that in white subjects, hyperhomocysteinaemia is not an independent risk factor for coronary artery disease and is associated with smoking. This may be of some consequence in view of the change to a more Western diet with more animal protein, and therefore methionine, coupled with a high frequency of cigarette smokers in this region. The causes of the hyperhomocysteinaemia are multifactorial but in this pilot study a deficiency of folate and/or vitamin B-12 did not seem to be one of them.

Adult↗
PubMed1995

Candidate genes for the phycoerythrocyanin alpha subunit lyase. Biochemical analysis of pecE and pecF interposon mutants.

The rod substructures of the Anabaena sp. PCC 7120 phycobilisome contain the light harvesting proteins C-phycocyanin and phycoerythrocyanin (PEC). Even at low light intensities, PEC represents no more than 5% of the phycobilisome protein. The beta subunits of both proteins carry thioether-linked phycocyanobilin (PCB) at beta-Cys-82 and beta-Cys-155; however, C-phycocyanin has PCB at alpha-Cys-84 whereas PEC alpha subunit carries phycobiliviolin at this position. The Anabaena sp. PCC 7120 pec operon is made up of five genes. PecB and pecA encode the beta and alpha subunits of PEC, pecC encodes a linker polypeptide associated with PEC in the rod substructure, and pecE and pecF are genes of unknown function that show a high degree of homology to cpcE and cpcF, that encode a C-phycocyanin alpha subunit PCB lyase (Fairchild, C. D., Zhao, J., Zhou, J., Colson, S. E., Bryant, D. A., and Glazer, A. N. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 7017-7021). Insertional mutants in pecE and pecF, and an interposon mutant in which a portion of both pecE and pecF was deleted, were constructed. All three types of mutants grew 1.3 times slower than wild-type under limiting light conditions and showed a 20% reduction in the PCB content of whole cells relative to chlorophyll alpha. Holo-PEC was missing from the phycobilisomes of all three types of mutants and the level of the PEC linker polypeptide was reduced relative to the wild-type. However, approximately 30% of the wild-type level of the PEC beta subunit was present in all of these phycobilisomes. In contrast, the PEC alpha subunit was barely detectable in the pecE and pecF mutants, but was present in the pecEF deletion mutant as a PCB-adduct in a 1:1 ratio with the PEC beta subunit. The identity of this "unnatural" adduct was confirmed by isolation of the subunit and amino-terminal sequencing. These biochemical results support the inference that pecE and pecF encode a PEC alpha subunit phycobiliviolin lyase, and, in conjunction with earlier findings, demonstrate that phycobiliprotein bilin lyases show high selectivity (rather than absolute specificity) for both the bilin and the polypeptide substrate.

Amino Acid Sequence↗
PubMed1995

A cross-sectional study of growth, puberty and endocrine function in patients with thalassaemia major in Hong Kong.

METHODOLOGY: A cross-sectional study of growth, puberty and endocrine function was performed on 35 girls and 33 boys with thalassaemia major. RESULTS: Despite regular transfusion and chelation therapy, 75% of the girls and 62% of the boys over the age of 12 years were below the third percentile for height. Hypogonadotropic hypogonadism was found in a similar percentage of patients. Moderate to marked zinc deficiency secondary to chelation therapy was considered unlikely because normal serum zinc levels were found in all but three of our patients, but we could not exclude the possibility of a marginal status of zinc nutrition causing growth failure. Growth hormone deficiency and diabetes mellitus were sometimes encountered but hypothyroidism, hypoparathyroidism and adrenal insufficiency were rare among our patients. Most of the patients with growth failure had normal growth hormone (GH) response to insulin induced hypoglycaemia. The serum insulin-like growth factor-1 (IGF-1) levels were low in our patients and no significant difference in the serum IGF-1 levels was found between prepubertal children with or without growth failure (0.4 +/- 0.1 mU/mL vs 0.37 +/- 0.11 mU/mL, P = 0.39). Similarly, no difference in the serum IGF-1 levels was found between pubertal children with or without growth failure (0.48 +/- 0.2 U/mL vs 0.56 +/- 0.14 U/mL, P = 0.26). CONCLUSIONS: Delayed sexual maturation and a possible defect in growth unrelated to the GH-IGF-1 axis may be responsible for the growth failure in adolescent children with thalassaemia major.

Adolescent↗
PubMed1995

Mixed chimerism following bone marrow transplantation for severe combined immunodeficiency: a study by DNA fingerprinting and simultaneous immunophenotyping and fluorescence in situ hybridisation.

We report a girl with severe combined immunodeficiency (SCID) who had a paternal T-depleted bone marrow transplant (BMT) when 11 months old. Engraftment was documented but karyotyping of marrow cells 1 year after BMT showed recipient metaphases (XX) only. However, she remained clinically well and further analysis y karyotyping of PHA-cultured peripheral blood mononuclear cells (PBMC) showed donor metaphases (XY) only. DNA fingerprinting confirmed mixed chimerism in the peripheral blood. The granulocytes were of recipient origin and the PBMC of mixed origin, the donor proportion of which increased after culture with PHA. Using simultaneous immunophenotyping and fluorescence in situ hybridisation (FISH) with chromosomes X and Y-specific probes, circulating T cells were demonstrated to be of donor origin whereas B cells and myeloid cells were mostly of recipient origin.

Adult↗
PubMed1994

Somatostatin therapy in L-asparaginase-induced pancreatitis.

L-Asparaginase-induced pancreatitis is an uncommon but potentially lethal complication. An 8-year-old girl with acute lymphoblastic leukaemia developed acute pancreatitis following treatment with asparaginase. Clinical and laboratory improvements were evident after treatment with somatostatin, with no complications of pancreatitis. Induction therapy for the leukaemia was able to be continued and complete remission was documented during the course of pancreatitis and somatostatin treatment, suggesting a beneficial role of somatostatin in the management of asparaginase-induced pancreatitis.

Acute Disease↗
PubMed1994

Intracellular calcium and myosin light chain phosphorylation during U46619-activated vascular contraction.

We investigated the relationship between [Ca2+]i, myosin light chain (LC20) phosphorylation and isometric force in guinea pig aortic strips during contractions activated by a thromboxane A2 analogue, (15S)-hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5Z, 13E-dienoic acid (U46619). Isometric force and [Ca2+]i were measured simultaneously using preloaded aequorin as the intracellular calcium indicator. LC20 phosphorylation levels were determined by two dimensional polyacrylamide gel electrophoresis in parallel preparations. Contractions induced by U46619 were accompanied by increases in [Ca2+]i and LC20 phosphorylation. The chelation of extracellular calcium with 2.5 mM EGTA significantly inhibited U46619-induced increases in [Ca2+]i, isometric force and LC20 phosphorylation. Steady-state force assumed a similar dependence on LC20 phosphorylation for contractions stimulated by potassium depolarization, alpha 1-adrenergic agonist phenylephrine and U46619 either in the presence or absence of extracellular calcium. On the contrary, the [Ca2+]i/force relation revealed that both U46619 and phenylephrine stimulated greater isometric force at lower [Ca2+]i than did KCl depolarization. The addition of a protein kinase C inhibitor, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), decreases force without significantly affecting either [Ca2+]i or LC20 phosphorylation levels. These results suggest that in guinea pig aortic smooth muscle U46619 increases the calcium sensitivity of the contractile apparatus but does not change the LC20 phosphorylation/force relation in comparison to K+ depolarization. Protein kinase C is activated during U46619-stimulated contraction and might be involved in mechanisms other than LC20 phosphorylation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

An outbreak of Pneumocystis carinii pneumonia in children with malignancy.

An outbreak of Pneumocystis carinii pneumonia (PCP) in three patients within a 6 week period was reported. Two patients had acute lymphoblastic leukaemia and one had brain-stem glioma. They shared common features of immunosuppression and absence of cotrimoxazole prophylaxis and had been nursed in the same room. The severity of PCP and its response to treatment may be related to the degree of immunosuppression. Because of the morbidity and mortality of PCP, chemoprophylaxis should be given to all at-risk cases. Furthermore, isolation of patients with PCP should be considered in view of increasing evidence of nosocomial transmission.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Hepatitis C virus antibody in multiply transfused Chinese with thalassaemia major.

Thirty-four of 99 multiply transfused Chinese (49 females, 50 males) with thalassaemia major were positive for antibody to hepatitis C virus. There was no sex predominance in seropositivity with 18 females and 16 males positive. The mean (+/- SD) age and units of blood transfused were significantly higher in the seropositive patients (167 +/- 48 months, 206 +/- 82 units respectively) than the seronegative patients (113 +/- 56 months, 124 +/- 80 units respectively). The seropositive patients had higher mean (+/- SD) serum alanine aminotransferase, aspartate aminotransferase and ferritin concentrations (91 +/- 82 IU/L, 67 +/- 38 IU/L, 4797 +/- 2522 ng/ml respectively) than the seronegative patients (38 +/- 29 IU/L, 48 +/- 28 IU/L, 3620 +/- 2140 ng/ml respectively). Serum ferritin had an independent and significant effect on serum alanine aminotransferase in addition to that of seropositivity to hepatitis C virus.

Alanine Transaminase↗
PubMed1993

Acetylpolyamines decrease blood pressure, [Ca++]i and isometric force of vascular smooth muscle.

Polyamines are polycations in cells and acetylation is the first step in their intracellular metabolism. We investigated the effects of the acetylated polyamines on arterial blood pressure and vascular reactivities in rats. Acetylspermine and acetylspermidine, administered at concentrations ranging from 12.5 to 50 mmol/kg b.wt., both induced a transient decrease in mean arterial blood pressure. The magnitudes of the hypotensive effects of these acetylpolyamines and polyamines were in the order of spermine > acetylspermine > acetylspermidine = spermidine. Pretreatment of rats with calcium diminished polyamine-induced hypotensive effects. The effects of spermine and acetylspermine on isolated vascular smooth muscle were examined in rat aortic rings and tail artery strips. Both compounds relaxed precontracted arterial preparations, and this relaxation could be counteracted by increasing extracellular calcium concentration. Tail artery strips were more sensitive to acetylspermine when compared to aortic rings. In tail artery strips preloaded with the bioluminescent protein aequorin, both spermine and acetylspermine caused a concomitant decrease in intracellular calcium and isometric force activated by 36 mM of KCl. These results demonstrate clearly that acetylspermine and spermine alike decrease intracellular calcium concentration of vascular smooth muscle, which is likely to account for the relaxation of vasculature. The relaxation of smooth muscle in the vascular wall in turn might lead to decreased arterial blood pressure.

Animals↗
PubMed1993

Bone marrow transplantation for thalassemia in Hong Kong: the early experience.

The first experience of bone marrow transplantation (BMT) for thalassemia in Hong Kong is reported. Of the three children transplanted using a matched allogeneic donor, two have been surviving disease free 291 and 256 days post-BMT respectively. The other child rejected the graft and remained transfusion dependent. Mild graft versus host disease occurred in one of the children which subsided on cyclosporin A alone. The regimen-related toxicities were mild and easily manageable. Thus the result is encouraging and the procedure is now accepted as an option of treatment for good risk patients in Hong Kong.

Bone Marrow Transplantation↗
PubMed1977

Acute haemorrhagic conjunctivitis in Hong Kong 1971-1975.

Acute haemorrhagic conjunctivitis occurred in epidemic in Hong Kong in 1971 and 1975 respectively. Two picornaviruses, the Enterovirus type 70 and an antigenic variant of Coxsackie virus type A24, were isolated during the 1971 outbreak, while only the latter virus was detected in the 1975 outbreak. In 1972 and 1974, sporadic cases of conjunctivitis associated with Enterovirus type 70 were observed. Serological survey in late 1975 showed a high proportion of the population might still be susceptible to both viruses. Recrudescence of the disease is conceivable when environmental condition is favourable for the spread of these viruses.

Adenoviruses, Human↗