Search PubMed⌕ Search

Biomedical subjects

L L Chan

Publications and source records attributed to L L Chan.

89 records · Page 5Linked to original sources
PubMed1996

Fractionated high-dose cyclophosphamide for advanced pediatric solid tumors.

PURPOSE: The objective of this study was to determine the tolerance and toxicities of high-dose cyclophosphamide (CPA) at 7 g/m2 given in four fractions over 8 h in children with advanced solid tumors. PATIENTS AND METHODS: Twenty children aged 1 1/2-19 years (median, 12 years) received 24 courses of high-dose CPA at 7 g/m2 for the treatment of advanced malignant solid tumor. CPA was given in four 1-h infusions of 1.75 g/m2 each, with 1 h of rest between each dose. MESNA was used as a uroprotective agent and was continued for 24 h after the final dose of CPA. With only one exception, all patients were discharged at the end of MESNA infusion and received granulocyte colony-stimulating factor, prophylactic ciprofloxacin, and co-trimoxazole. RESULTS: Severe but transient myelosuppression was observed. The median time to neutrophil and platelet recovery was 17 and 19 days, respectively. Fever developed after 13 of the 24 courses, and hospitalization was required. Extramedullary toxicities were mild. No patient showed cardiomyopathy or hemorrhagic cystitis. Forty-six percent of the courses were managed entirely on an outpatient basis. Objective tumor response was seen in five patients. CONCLUSIONS: CPA at 7 g/m2 is well tolerated by children with advanced malignancies and should be considered in earlier phases of antineoplastic therapy.

Adolescent↗
PubMed1996

HIV infection and AIDS in China, 1985 through 1994.

OBJECTIVES: This paper analyzes data on the distribution of and risk factors for the acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection in China. METHODS: Ten years of data on persons tested for HIV infection and AIDS and the proportion who tested positive were analyzed against the background of China's population count. The Chinese- and English-language literature on HIV and AIDS from 1985 through 1995 was also reviewed. RESULTS: Overall, more males than females had HIV infection. Intravenous drug use was the primary source of transmission, followed by heterosexual contacts. Only a small number of the persons tested were homosexual, but their proportion of HIV seropositivity ranked third to that of drug users; that of general hospital patients ranked fourth. CONCLUSIONS: HIV infection and AIDS in China began as a highly regionalized and largely rural problem in Yunnan Province. However, HIV infection and AIDS have become an emerging urban problem. HIV seropositivity is low among several groups thought to have an elevated risk.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Successful allogeneic bone marrow transplantation in severe chronic mucocutaneous candidiasis syndrome.

We report the successful HLA-identical sibling bone marrow transplantation (BMT) of a 12-year-old boy with chronic mucocutaneous candidiasis (CMC) syndrome who also had Coomb's positive haemolytic anaemia and recurrent bronchopneumonia with resulting bronchiectasis. Conditioning was with busulfan and cyclophosphamide. Engraftment was slow but complete. Selective red cell haemopoietic failure was encountered soon after transplantation but resolved spontaneously. The patient remains alive 3 years after transplantation and now has normal immune, haemopoeitic and pulmonary functions. No manifestation of CMC has been evident since transplantation.

ABO Blood-Group System↗
PubMed1995

p16INK4A and p15INK4B gene deletions in primary leukemias.

The 9p21 locus has been deleted at a high frequency in a wide variety of tumors. Recently, two genes, p16INK4A and p15INK4B (also called MTS1 and MTS2), have been localized in close proximity at the 9p21 locus, encoding cyclin-dependent kinases 4/6 inhibitors of relative molecular mass 16 kD and 15 kD, respectively and also found to be deleted at a high frequency in tumor cell lines. We analyzed p16INK4A and p15INK4B genes in 178 cases of primary leukemias including 81 cases of chronic lymphocytic leukemia (CLL), seven of hairy cell leukemia (HCL), seven of chronic myelogenous leukemia (CML), 43 of acute myelogenous leukemia (AML), 27 of acute lymphoblastic leukemia (ALL), and 13 of myelodysplastic syndrome (MDS) by Southern blot analyses. The ALL cases showed a relatively high frequency of homozygous deletions (22%, 6 of 27) at the p16INK4A gene locus. Interestingly, of the six cases with p16INK4A homozygous deletions, only three showed homozygous deletions at the p15INK4B gene. In 81 CLL patients, we detected one homozygous and five heterozygous deletions at both the p16INK4A and p15INK4B genes and two heterozygous deletions at the p16INK4A gene alone. Deletion of these two genes in AML cases is relatively low (9%). We did not detect deletions in any of the MDS, HCL, and CML cases examined. Sequence analyses of p16INK4A gene of six CLL cases with heterozygous deletion at this locus showed a 27-bp deletion at the splice acceptor site of intron 1 in one case and changes in the coding sequence in three other cases. The data presented in this report showed that (1) p16INK4A and p15INK4B genes are preferentially deleted homozygously in ALL and heterozygously in CLL cases with frequent mutation in the second allele, and (2) p16INK4A gene appears to be more frequently deleted than p15INK4B gene.

Base Sequence↗
PubMed1994

Bone marrow transplantation in Malaysia.

The sole BMT centre in Malaysia caters only for children. Since 1987, 89 transplants have been performed using reverse barrier nursing techniques. The overall survival rate is 73% with the majority of survivors leading normal lives. The early and late infection rates of 46% and 13%, respectively, are comparable to those of other centres. Although the early septicaemia rate is 36% the immediate mortality rate is < 10%. GVHD is less frequent and severe and the interstitial pneumonitis rate lower than that in the West. The average cost of US $8000 per transplant is much lower than the cost of a transplant performed overseas. Thus we believe that our paediatric BMT programme is simple and cost-effective.

Adolescent↗
PubMed1993

Factors affecting hair regrowth after bone marrow transplantation.

Permanent alopecia after BMT has been reported as a side-effect associated with GVHD or after busulphan conditioning therapy, primarily in adults. We have reviewed children undergoing BMT to document the frequency of incomplete hair regrowth and to evaluate factors associated with this problem. Hair regrowth was studied in 74 children who survived > 6 months following BMT undertaken for malignant and non-malignant diseases. Alopecia was categorised as severe (< 50% of pre-transplant status), moderate (50-75%) or mild (> 75% but less than normal). Overall, 18 (24.3%) of 74 patients had mild (n = 5), moderate (n = 4) or severe (n = 9) alopecia. Risk factors for alopecia were presence of chronic GVHD (67%; p < 0.001), older age (p < 0.001) and prior cranial irradiation (42%; p = 0.03). Alopecia occurred in children receiving either busulphan (31%) or total body irradiation (16%; p = 0.15) as conditioning therapy. The highest frequency was seen in patients conditioned with busulphan with or without melphalan and who received prior cranial irradiation and/or developed chronic GVHD (75%). These data indicate that alopecia after BMT in children is a significant problem and confirm, in children, the previously noted association between alopecia and chronic GVHD and busulphan. Further risk factors of older age and prior cranial irradiation are identified. Consideration needs to be given to the use of an alternative to busulphan in children who are of older age, have received prior cranial irradiation and/or are at increased risk of GVHD.

Adolescent↗
PubMed1992

Prenatal diagnosis of intestinal obstruction due to ileal atresia.

A case of intestinal obstruction due to ileal atresia where the diagnosis was made prenatally by ultrasound is presented. Close monitoring of the fetus was done ultrasonographically to look for any evidence of meconium peritonitis. The baby was delivered preterm but weighed 3.3 kg. Laparotomy and enterostomy was done and the baby is currently well.

Female↗
PubMed1991

Public health--in search of a knowledge domain and expert reference advisory system.

The rationale, development, and implementation of a computer-based reference advisory system (RAS) in public health called Public Health Librarian (PHL) are described. The general purpose of RAS is to provide reference tool suggestions to students in the highly diversified studies of public health in San Diego State University's Graduate School of Public Health. The multidisciplinary nature of public health lends itself to the design of RAS, which brings together key resources across the boundaries of social and medical sciences.

Expert Systems↗
PubMed1981

Plasma "prorenin"-renin in Bartter's syndrome, cystic fibrosis, and chloride deficiency, and the effect of prostaglandin synthetase inhibition.

In Bartter's syndrome and in other states with ECFV contraction, very high active plasma renin (PRA greater than 78 ng/ml/hr) is associated with an essential absence of prorenin. In patients whose PRA is less than 50 ng/ml/hr, prorenin accumulates significantly. Patients with Bartter's syndrome treated with PG synthetase inhibitors for 1 week respond with a profound drop in renin, together with a rise in prorenin. Thus, in general, highest active renin values coexist with virtually no prorenin, moderately high renins with rising prorenin, and renins "blocked" by PG synthetase inhibitors with highest prorenin levels. Such a reciprocity between prorenin and renin suggests systemic conversion by means of a convertase mechanism apparently susceptible to PG synthetase inhibitors in vivo but not in vitro. It is also possible that these inhibitors suppress in vivo, but not in vitro, renal renin release more than prorenin release, so that the relative level of prorenin increases. This, coupled with decreased conversion to renin, may contribute to the observed elevation of prorenin.

Adolescent↗
PubMed1981

Net acid excretion during first week of life.

Metabolic acidosis occurs frequently in newborns. Net acid excretion (NAE) in 34 preterm and 12 term infants was measured during the first week of life. Twenty preterm infants received breast milk or formula; the remaining infants received total parenteral nutrition (TPN) -- synthetic amino acids or casein hydrolysate solution. NAE for breast milk vs formula fed infants was 5.4 +/- 0.4 and 7.8 +/- 0.6 muEq/min/m2 (mean +/- SEM). The corresponding values for the two TPN solutions in preterm infants were significantly higher at 12.5 +/- 1.4 and 19.4 +/- 3.5 muEq/min/m2. Term infants produced even greater amount of net acid, 20.6 +/- 2.9 and 35 +/- 3.7 muEq/min/m2 respectively for the two TPN solutions. Milk fed infants are less prone to acidosis because of base generated from milk consumption. Due to its inherent acidogenic effect, TPN solutions induce acidosis more readily. Infants receiving TPN are therefore required to generate a higher NAE rate to maintain acid-base homeostasis compared to milk fed infants.

Acid-Base Equilibrium↗
PubMed1977

Essential hypertension in childhood.

Fifteen patients, aged 8 to 17 years, were found to have hpertension and were studied from February 1974 to Decemober 1975. Hypertension was defined as supine diastolic blood pressure repeatedly above 90 mm Hg. Five patients had a family history of hypertension. Extensive diagnostic evaluation performed in all cases failed to show an underlying cause for the hypertension. Patients with target-organ involvement were treated with hydrochlorothiazide; five of them are currently normotensive. Of the remaining nine untreated patients, four became spontaneously normotensive within eight to 14 months of the initial evaluation. These results suggest that extensive studies in children with hypertension may not be necessary in every case if clinical findings meet the critiera for the diagnosis of essential hypertension. These studies might be desirable, however, if target-organ involvement is present.

Adolescent↗
PubMed1977

Changes in the composition of plasma membrane proteins during differentiation of embryonic chick erythroid cell.

Erythroid cells which are homogeneous with regard to stage of maturation are naturally available from the circulation of chick embryos at various times of development. This provides a convenient system for examining the changes in plasma membrane protein composition during red cell maturation. Plasma membranes are isolated from chick embryonic erythroid cells at various stages of maturation. Extensive characterization of the isolated membranes show that they are pure and their proteins undegraded. Analyses by sodium dodecyl sulfate/polyacrylamide gel electrophoresis show that both qualitative and quantitative changes occur in membrane protein composition during the early stage of erythroid differentiation. Specific proteins of red cell membrane such as "spectrin" and band three proteins are present in low levels in early erythroblasts but increase in their relative amounts with maturation. A steady-state membrane protein composition seems to be established by the late polychromatophilic erythroblast stage.

Age Factors↗
PubMedDate not supplied

Chronic isolated vertigo.

Vertigo can be the first manifestation of vertebrobasilar ischaemia or brainstem and cerebellar stroke. Chronic isolated vertigo may pose a diagnostic dilemma. We report the case of a patient who presented with chronic isolated vertigo, and highlight the clinical use of magnetic resonance imaging and angiography in his management.

Brain Ischemia↗