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Biomedical subjects

D Leung

Publications and source records attributed to D Leung.

12 recordsLinked to original sources
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

Serodiagnosis of Lyme borreliosis by western immunoblot: reactivity of various significant antibodies against Borrelia burgdorferi.

The significance of various antibodies against Borrelia burgdorferi was studied by Western blot (immunoblot) by using 578 human serum samples. The proteins regularly detected by using samples from patients with Lyme borreliosis were those with bands with molecular masses of 94, 83, 75, 66, 60, 55, 46, 41, 39, 34, 31, 29, 22, and 17 kDa. The detectable frequencies of most of these proteins appeared to be significantly different between the sera from patients with Lyme borreliosis and those from normal control individuals as well as from the group with syphilis. The 39-kDa protein band recognized by polyvalent antibody was found to be the most significant marker for Lyme borreliosis. Furthermore, an anti-39-kDa immunoglobulin M response was detected in the samples from patients with early-stage Lyme borreliosis. Results from the use of monoclonal antibodies and patient sera revealed that the 39- and 41-kDa proteins may be structurally related but are immunologically distinct antigens. The significance of antibody reactivities to the 41-, 94-, 22-, 31-, and 34-kDa protein bands is also discussed.

Antibodies, Bacterial↗
PubMed1991

Are demented patients with Parkinson's disease accurately reflected in prevalence surveys? A survival analysis.

We re-reviewed 257 patient records previously reviewed for an incidence study of dementia in Parkinson's disease (PD) to determine the frequency, date of death, and cause of death. We posited that if disease duration is shortened when dementia occurs, then dementia may be far more common than reflected in prevalence studies. There were 17 deaths among 65 demented patients and 28 deaths among 168 nondemented patients. When we matched a subset of the nondemented patients to the demented patients by age and disease duration distributions, the demented subjects had significantly more deaths (p less than 0.02), and survival among demented subjects was decreased (p less than 0.05). Dementia was a significant predictor of death in this sample. We conclude that dementia reduces survival in patients with PD. Incidence is a much better measure of dementia in PD than prevalence because shortened duration makes it less likely to detect dementia in prevalence surveys.

Aged↗
PubMed1990

The ANB1 locus of Saccharomyces cerevisiae encodes the protein synthesis initiation factor eIF-4D.

The Saccharomyces cerevisiae anaerobic gene (ANB1) is negatively regulated both by oxygen and heme. We have shown recently that an upstream repressor site located in the 5'-flanking region of this gene controls its expression (Mehta, K.D., and Smith, M. (1989) J. Biol. Chem. 265, 8670-8675). In this paper, we present the complete genomic sequence of the ANB1 locus of S. cerevisiae. The ANB1 locus encodes a protein of 157 residues with an Mr of 17, 134. The deduced amino acid sequence of the ANB1 gene product shows strikingly extensive sequence and structural homology (63.5% identical residues and an additional 15% conservative substitutions) to the 154-amino-acid-long human and rabbit eukaryotic translation initiator factor (eIF)-4D. Factor eIF-4D is the only known mammalian protein that undergoes a unique post-translational modification of Lys-50 to the amino acid hypusine, and interestingly the same lysine is also present in the ANB1 gene product. Results presented provide strong evidence that the ANB1 locus that encodes a transcript, tr-2, and a second locus encoding a transcript, tr-1, together encode two forms of yeast eIF-4D. Interestingly, heme regulates both the loci in an opposite manner; as a result it can dictate the isoform available under conditions of high and low oxygen tension. The ROX1 locus of S. cerevisiae is known to regulate CYC1, COXVb, and ANB1 genes at the transcriptional level; the ROX1 locus thus regulates all known anaerobically expressed genes that are involved in different cellular functions such as respiration and protein synthesis.

Amino Acid Sequence↗
PubMed1981

Antiviral activities of hybrids of two major human leukocyte interferons.

Four hybrid human leukocyte interferon (LeIF or IFN-alpha) genes have been constructed by in vitro recombination of LeIF-A (IFN-alpha 2) and LeIF-D (IFN-alpha 1) genes at common restriction endonuclease sites located within their coding regions. These hybrid genes have been expressed in E. coli under trp promoter control. The interferons produced [LeIF-AD (BglII), -AD (PvuII), -DA (BglII), -DA (PvuII)] have antiviral properties distinct from the parental molecules LeIF-A and -D, varying considerably in their abilities to inhibit plaque formation by different viruses in a range of mammalian cells. All six of the cloned LeIFs exhibit the heat stability, pH 2 stability and antigenic specificity of natural leukocyte interferons.

Animals↗
PubMed1981

Bacterial synthesis of a novel human leukocyte interferon.

A novel human leukocyte interferon cDNA clone (LeIF B) was identified in a cDNA library prepared using polyadenylated mRNA of a myeloblastoid cell line. The nucleotide sequence of LeIF B differs significantly from other published leukocyte interferon cDNA sequences. An expression plasmid was constructed which directs the synthesis in E. coli of 8 x 10(7) interferon units per liter of culture. LeIF B exhibits markedly different specificities from another bacterially synthesized human leukocyte interferon, LeIF A.

Base Sequence↗
PubMed1980

Synthesis of human fibroblast interferon by E. coli.

A cDNA library was constructed using mRNA from human fibroblasts induced with poly(I):poly(C). A bacterial clone containing fibroblast interferon cDNA sequences was identified by hybridization to a cDNA probe synthesized using deoxyoligonucleotide primers which hybridize to fibroblast interferon mRNA specifically. Expression plasmids were constructed which permitted the synthesis in E. coli of 8 x 10(7) units of human fibroblast interferon per liter of culture. The bacterially produced fibroblast interferon is indistinguishable from authentic human fibroblast interferon by several criteria.

Amino Acid Sequence↗
PubMed1978

Plasma concentrations of isosorbide dinitrate and its metabolites after chronic high oral dosage in man.

1 We have previously reported that vasodilator headache due to isosorbide dinitrate (ISDN) can be circumvented by using small 'priming' doses for an induction period of 1-2 weeks, after which it is possible to increase to dose rapidly to 360-720 mg, daily without recurrence of headache and without toxicity. The present study corroborates this earlier finding. 2. Chronic oral administration of doses of ISDN of this order of magnitude results in prolonged high plasma concentrations of the parent compound, as well as higher levels of the metabolites 2-ISMN and 5-ISMN. 3. It is our thesis that chronic high oral dosage of ISDN saturates the intrahepatic biotransformation process, and allows high concentrations of ISDN and its metabolites to enter the systemic circulation.

Administration, Oral↗
PubMed1975

Effect of DNA delay mutations of bacteriophage T4 on genetic recombination.

Studies have been made of the effect of the DNA delay mutations of bacteriophage T4 on growth and genetic recombination in a number of Escherichia coli hosts. DNA delay mutations in genes 39, 52, 58 (61), and 60 result in abnormally high recombination frequencies. These high recombination frequencies are discussed in the context of other observations.

Coliphages↗
PubMed1974

Acupuncture.

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Acupuncture Therapy↗