Biomedical subjects
W L Lim
Publications and source records attributed to W L Lim.
Is vaccination of donor adequate for clearance of hepatitis B virus after bone-marrow transplantation?
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Parvovirus B19 infection in Hong Kong.
Human parvovirus B19 is a small DNA virus that can cause a number of diseases, notably erythema infectiosum in children, and aplastic crisis in patients with chronic haemolytic disorders. With the availability of serological tests for parvovirus infection, much is known about the prevalence of this virus in the Western population. However, there have not been any data on the epidemiological pattern of parvovirus B19 infection in Hong Kong and its surrounding region. In this report we have studied the sero-prevalence of parvovirus B19 in Hong Kong in 1983 and 1993, and were able to show a low incidence of parvovirus infection in the intervening 10 years, leading to a shift in the prevalence rate of parvovirus infection in the general population. From 1991 to 1996, of 276 patients presenting with illness which might have been caused by B19, only 2.5% were positive for IgM and 19.6% for IgG anti-B19. The prevalence of IgG anti-B19 among patients with thalassaemia major requiring frequent blood transfusion in 1995 was similar to those in the same age group in the general population, substantiating the observation that B19 infection was not common in Hong Kong in recent years.
Breastfeeding at 6 weeks and predictive factors.
Despite the numerous changes made in accordance with the Baby Friendly Hospital Initiative at the University Hospital, Kuala Lumpur, the low rates of breastfeeding have persisted. This study aims to examine the current trend in infant feeding, and the influences of some perinatal and sociodemographic factors on breastfeeding. Five-hundred mothers with singleton pregnancies and healthy infants were interviewed at 6 weeks post-partum. Only 124 (25 per cent) mothers were practising exclusive breastfeeding (EBF), and 132 (26 per cent) mothers were using exclusive infant formula feeding (EIF). On logistic regression analyses, mothers who followed EBF were more likely to have had antenatal plans to breastfeed (Odds ratio 2.44, 95 per cent confidence interval 1.75-3.45), not in paid employment post-natally (OR 1.76, 95 per cent CI 1.31-2.36), of older age group (> 27 years) (OR 1.48, 95 per cent CI 1.13-1.93), had female infants (OR 1.38, 95 per cent CI 1.05-1.80) and of Indian ethnicity (compared to Chinese) (OR 3.87, 95 per cent CI 2.16-6.89). Breastfeeding difficulties were associated with decreased odds of EBF (OR 0.21, 95 per cent CI 0.13-0.34). Parental education, fathers' ages and incomes, primigravida status, Caesarean section, present of episiotomy, late first breastfeed, phototherapy, and length of hospital stay were not significant predictors of failure of EBF. In comparison, predictive factors for increased use of EIF were mothers who have had breastfeeding difficulties, < or = 9 years of schooling, and of Chinese descent. In conclusions, the overall rate of EBF by 6 weeks of age in infants born in this urban hospital had remained poor. The adverse factors for EBF identified in this study warrant further in-depth studies to determine effective ways of improving EBF rates.
Epstein-Barr virus associated parotitis.
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Persistence of hepatic hepatitis B virus after serological clearance of HBsAg with autologous peripheral stem cell transplantation.
Delayed clearance of hepatitis B surface antigen was previously reported in a 38 year old woman after high dose chemotherapy with autologous peripheral blood stem cell rescue. Sixteen months later, this patient remained hepatitis B surface antigen negative, hepatitis B surface antibody positive, and serum hepatitis B DNA negative by polymerase chain reaction. Serial liver biopsies (one at hepatitis B e antigen positive stage, one at hepatitis B e antibody positive stage, and one at hepatitis B surface antigen negative and hepatitis B surface antibody positive stage) showed a gradual resolution of the inflammatory activity with loss of hepatitis B e antigen and then hepatitis B surface antigen in the serum. However, the degree of fibrosis, though mild, remained the same. With the serological clearance of hepatitis B surface antigen, a small amount of hepatitis B virus DNA was still detectable in the nuclei of liver cells.
Inactivated hepatitis A vaccine in healthy Chinese adults.
OBJECTIVES: To study the safety, tolerability of and immune response to an inactivated hepatitis A vaccine in healthy Chinese adults. DESIGN: Seronegative subjects were randomized to receive formalin-inactivated, alum-adjuvanted hepatitis A vaccine (25 units, MSD) at 0, 24 weeks (group I) or 0, 2, 24 weeks (group II). SUBJECTS: Healthy Chinese adults aged 18 years or above were recruited. All subjects were staff of a regional hospital and primary care clinic in Hong Kong. MAIN OUTCOME MEASURES: Side-effects, tolerance, seroconversion rate and geometric mean titre (GMT) of the two groups were noted and compared. RESULTS: Thirty-two and 28 people were recruited into group I and group II, respectively. Antibody against hepatitis A developed in 100% of the recipients 1 month after the last dose of either regimen, with a GMT of around 450 IU L-1. High antibody levels were maintained at the end of one year. There was no statistically significant difference in the seroconversion rates and GMTs between the two regimens of vaccination. All subjects in group I seroconverted at 24 weeks after one single dose of the vaccine. No adverse effects were reported except for complaints of some mild local and constitutional symptoms. CONCLUSIONS: The inactivated hepatitis A vaccine is highly immunogenic, safe and well-tolerated.
Anamnestic responses of infants after regular or reduced doses of hepatitis B vaccine.
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A reduced dose approach to hepatitis B vaccination for low-risk newborns and preschool children.
The effectiveness of a 2.5 micrograms dose of the hepatitis B vaccine (B-Hepavac II) was compared with that of 5 micrograms in 587 low-risk neonates and 777 preschool children of age 3-8 years. The vaccines were administered at months 0, 1 and 3, with postvaccination serology tested at months 4 and 12. The seroconversion rates of the 2.5 microgram recipients (newborn: 93.5%; preschool children: 97.4%) are comparable with the 5 micrograms group (newborn: 95.7%; preschool children: 98.7%). The seroconversion rates of the newborns are, however, significantly lower in the 2.5 micrograms group if positive response is taken as a titre > 10 IU l-1, instead of > 0 IU l-1. The older children, on the other hand, achieved a higher seroconversion rate and geometric mean titre (GMT) when compared with the newborns. irrespective of the dose received.
Changing prevalence of hepatitis B virus and hepatitis D virus infection among injecting drug users in Hong Kong indicating a change in high-risk behaviour.
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Five-year follow-up of a prospective randomized trial of hepatitis B recombinant DNA yeast vaccine vs. plasma-derived vaccine in children: immunogenicity and anamnestic responses.
In a prospective randomized trial, 318 children aged between 3 mo and 11 yr who were negative for all hepatitis B markers were randomized to receive two 5-micrograms doses of hepatitis B recombinant DNA yeast vaccine at 0 and 1 mo (group 1), three 5-micrograms doses of hepatitis B recombinant DNA yeast vaccine at 0, 1 and 6 mo (group 2) or three 10-micrograms doses of plasma-derived hepatitis B vaccine (group 3). The HBs antibody response rate at 8 mo was between 93% and 99%; it was still 75% to 87% at 5 yr in all three groups. Geometric mean titers at 1 yr were 83, 1,085 and 858 mIU/ml in groups 1, 2 and 3, respectively. These values had decreased after 5 yr to 47, 131 and 250 mIU/ml. Subjects in group 1 showed a significantly less proportional drop in geometric mean titer at the fifth year than did subjects in group 2 (p = 0.05) or group 3 (p = 0.015). None of the children developed HBc antibody, even after 5 yr of follow-up. We noted 42 episodes of significantly increased HBs antibody titers, probably due to anamnestic response, even when the titers had dropped to low levels. The mean age at which anamnestic response occurred was 8.7 yr.(ABSTRACT TRUNCATED AT 250 WORDS)
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.
Antibody-capture particle-adherence test for antibody to HIV-1 in urine.
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Interactions between callosal, thalamic and associational projections to the visual cortex of the developing rat.
The patterns of callosal interconnections between the visual cortices of rats display considerable plasticity in response to various neonatal manipulations. In the present study, many neurones in the principal visual thalamic relay nuclei, the dorsal lateral geniculate nucleus (DLG) and to a lesser extent those in the lateral posterior nucleus (LP) were destroyed by injections of the neurotoxin - kainic acid - on the first day of postnatal life. Four weeks later, as demonstrated with the anterograde and retrograde transport of the enzyme horseradish peroxidase (HRP) injected into the occipital lobe of one hemisphere, callosally projecting neurones and terminals were distributed more widely in the retinotopically organized areas 17, 18a and 18b of the visual cortex ipsilateral to the lesioned visual thalamus than in unoperated control animals of the same age. By contrast, in the visual cortex contralateral to the lesioned visual thalamus the areal distribution of callosally projecting neurones and terminals was similar to that of the controls, that is, largely but not exclusively restricted to the common border of areas 17 and 18a. Both in unoperated and operated animals, cells in lamina V of several cytoarchitectonically defined areas that are not retinotopically organized (area 8 in the frontal lobe, area 29d in the retrosplenial limbic cortex and perirhinal areas 35/13 in the temporal lobe) also project to contralateral visual cortices. In areas 8 and 29d, the total numbers, laminar distributions and densities of labelled callosal cells both ipsilateral and contralateral to the kainate-injected visual thalamus were similar to those in the controls. However, in the temporal lobe, the areal distribution of the labelled callosal neurones was more extensive than that in the controls and labelled cells in areas 35/13 of the cortex contralateral to the kainate-lesioned visual thalamus merged with those in the neighbouring areas 20 and 36. By contrast, the areal distribution of associational neurones in area 18a and in nonretinotopically organized areas projecting to area 17 were very similar in controls and in operated animals (neonatal kainate lesion of the visual thalamus, neonatal section of the corpus callosum or both procedures combined). However, in operated animals, the labelled associational neurones projecting from the supragranular laminae (II/III) of area 18a to area 17 constituted a higher proportion of all cells than did those in the unoperated control animals. Thus, overall the number of associational neurones projecting from area 18a to area 17 was slightly increased by the experimental manipulations performed.(ABSTRACT TRUNCATED AT 400 WORDS)
Pyogenic meningitis in hospitalized children in Kelantan, Malaysia.
A 2.5-year retrospective study of pyogenic meningitis in hospitalized children in Kelantan was carried out with regard to aetiology, clinical features, investigation, treatment and outcome. There were 58 children with 43 cases (74.1%) occurring below the age of 1 year. Frequent presenting symptoms included fever (98.3%), fits (77.6%), anorexia (39.7%), vomiting (34.5%) and drowsiness (12.1%). On admission, 37 (63.7%) had neck stiffness, 10 (17.2%) had Kernig's sign and 32 (55.2%) had coma. CSF cultures were positive for Haemophilus influenzae in 29 (50%), Streptococcus pneumonia in 13 (22.4%) and Neisseria meningitidis in 3 (5.2%). The antibiotic sensitivity profiles showed that the three main organisms were 100% sensitive to Chloramphenicol, Streptococcus pneumoniae was 100% sensitive to penicillin, Neisseria meningitidis was 100% sensitive to penicillin and ampicillin, and Haemophilus influenzae was 90% sensitive to penicillin and ampicillin. The total hospital mortality was 18.9%. All but two of the eleven deaths occurred in children younger than 1 year. Nineteen of the 35 (54.3%) survivors attended for at least one follow-up after discharge from hospital. Of these 19 children, 47.4% had neurological sequelae.
Role of target tissue in regulating the development of retinal ganglion cells in the albino rat: effects of kainate lesions in the superior colliculus.
Kainic acid or ibotenic acid was injected unilaterally into the major target regions of the axons of retinal ganglion cells--the superior colliculus (SC) or dorsal lateral geniculate nucleus (DLG)--of rat pups ranging in age from postnatal day 0 to postnatal day 10 (P0 - P10). While the collicular or geniculate neurons within the injection site died within 48 hours of the injection, damage to axons and terminals of extrinsic origin within the injected region was not apparent. The neuronal degeneration induced by the neurotoxins, observed at both the light and electron microscopic levels, resembled the neuronal degeneration that occurs in the colliculus during normal development. Macrophages were identified in the regions containing degenerating cells. Two to three weeks after the injections of neurotoxin, massive injections of the enzyme, horseradish peroxidase (HRP), were made into the retinorecipient nuclei. After about 24-hour survival time the numbers of retinal ganglion cells were estimated by counting the number of neurons containing HRP reaction products in sample areas distributed in a regular rectangular array across the entire retinal surface. In the animals in which the neurotoxin was injected into the SC during the first 4 postnatal days, there was a substantial reduction (on average 41.5%; the range: 27.5-65.5%) in the normal number (mean value of 113,000--Potts et al.: Dev. Brain Res. 3:481-486, '82) of retinal ganglion cells surviving the period of "naturally occurring ganglion cell death" in the retinae contralateral to the injected SC. By contrast, injections of neurotoxins into the DLG and/or the optic tract of newborn rats did not result in a significant reduction in the numbers of retinal ganglion cells surviving the period of naturally occurring ganglion cell death. The period of sensitivity of retinal ganglion cells to the injection of neurotoxin into the colliculi extends from birth to about the end of the first postnatal week; the greatest sensitivity seems to be restricted to the first 3-4 postnatal days. In the retinae in which the total number (and density) of ganglion cells was substantially reduced by the selective destruction of their target cells, the centro-peripheral difference in the somal diameters of the ganglion cells (apparent in normal animals) was abolished, both amongst the whole population of ganglion cells and amongst the ganglion cells with the largest somata, relatively thick axons, and large-gauge primary dendrites (Class I cells). The number and distribution of the Class I cells in the depleted retinae were, however, unaltered.(ABSTRACT TRUNCATED AT 400 WORDS)
Scanning electron-microscopic evidence for attachment of a nonpersistently transmitted virus to its vector's stylets.
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