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Biomedical subjects

K L Tan

Publications and source records attributed to K L Tan.

At least 19 recordsLinked to original sources
PubMed1992

Descriptive profile of birth defects among livebirths in Singapore.

A case-control study of birth defects was carried out in Kandang Kerbau Hospital in Singapore for a three-year period from January 1986 until December 1988. This paper presents the descriptive profile of birth defects among livebirths seen in that hospital. Out of 44,842 livebirths, 678 babies were found to have birth defects, giving a prevalence of 15.13 per 1000 livebirths (95% CI 14.0-16.2). The musculoskeletal system was the most frequently affected system accounting for 161 cases with a prevalence of 3.59 per 1,000 livebirths (95% CI 3.06-4.19), followed by 111 cases with defects of the gastrointestinal system (2.47 per 1,000 livebirths 95% CI 2.04-2.98), 88 cases of chromosomal disorders (prevalence of 1.96 per 1,000 livebirths 95% CI 1.57-2.42), 78 cases with defects of the cardiovascular system (1.74 per 1,000 livebirths 95% CI 1.38-2.17), 73 cases with defects of the urogenital system (1.63 per 1,000 livebirths 95% CI 1.28-2.05), and 52 cases with defects of the central nervous system (1.16 per 1,000 livebirths 95% CI 0.87-1.52). The prevalence of cleft lip, cleft palate in isolation, and cleft lip and palate combined was 1.72 per 1,000 livebirths and the occurrence of Down's syndrome was 1 in 700 livebirths. When reviewed 6 weeks postpartum, the rate of false positives at birth was 4%. In a control group of 709 "normal" cases at birth, the rate of cases not detected at birth but detected at 6 week follow-up, false negatives was 0.84%.

Case-Control Studies↗
PubMed1992

Phototherapy and the brain-stem auditory evoked response in neonatal hyperbilirubinemia.

The latencies of peak V and interpeaks I-V and III-V in the brain-stem auditory evoked response of infants with hyperbilirubinemia before phototherapy were significantly greater than those in a control group of infants. These values of the brain stem auditory-evoked response improved significantly during phototherapy and correlated significantly with the declining bilirubin levels. Improvement continued after phototherapy, despite a rebound of serum bilirubin concentrations.

Bilirubin↗
PubMed1992

Efficacy of "high-intensity" blue-light and "standard" daylight phototherapy for non-haemolytic hyperbilirubinaemia.

We report our clinical experience with phototherapy in 3802 infants; 3629 were exposed to "standard" daylight phototherapy and 173 to "high-intensity" blue-light phototherapy. High-intensity blue-light phototherapy was twice as effective as standard daylight phototherapy in decreasing bilirubin concentrations. No failures occurred with high-intensity phototherapy compared with an overall failure rate of 1.84/1000 with daylight lamps; these cases were transferred to high-intensity phototherapy with prompt response. Rebound after cessation of phototherapy was greater in those exposed to high-intensity blue light with a significantly greater number requiring a second exposure. However, the incidence was still low. No third exposure was required in any infant. Nursing of infants under high-intensity blue light was more difficult and inconvenient as was clinical monitoring. The light also caused more stress on the nursing and medical personnel. However, the infants tolerated both types of phototherapy equally well. High-intensity blue-light phototherapy would seem to be the treatment of choice for infants with rapidly increasing or very high bilirubin levels, as well as in those not responding adequately to daylight phototherapy.

Bilirubin↗
PubMed1992

Phototherapy for ABO haemolytic hyperbilirubinaemia.

The efficacy of 'standard' daylight phototherapy and 'high intensity' blue light phototherapy for neonatal jaundice from ABO-HD, or of a non-haemolytic nature was evaluated. Altogether 77 full-term infants with ABO-HD and 3,020 with non-haemolytic jaundice were studied. Both groups of infants responded well to standard daylight phototherapy; the response in non-haemolytic hyperbilirubinaemia was significantly greater. High intensity blue light phototherapy was significantly more effective in reducing bilirubin levels than standard daylight phototherapy in both group of infants with no failure being encountered. Four infants with non-haemolytic jaundice did not respond adequately to white light (1.4/1,000); they needed high intensity blue light for adequate response. Bilirubin rebound was mild. Four infants in the blue light group needed a second exposure (28.3/1,000) compared with 20 in the white light group (6.9/1,000), a difference that was significant. Standard white light phototherapy is usually adequate for ABO-HD as well as non-haemolytic hyperbilirubinaemia. High intensity blue light would be preferable where a more rapid and greater response is desirable.

ABO Blood-Group System↗
PubMed1992

Immunolabelling of prolactin at ultrastructural level using the protein A-gold technique on Epon-embedded tissue.

The use of the colloidal-gold technique in electron microscopy immunocytochemistry has provided important information on the in situ localisation of intracellular antigens. We have developed a post-embedding technique for prolactin localisation on resin-embedded human pituitary tissue sections by the use of the protein-A gold conjugate. Human pituitary tissue obtained at autopsy was processed for electron microscopical study without post-osmication and then embedded in Epon. The indirect immunoperoxidase method was used for light microscopical targetting of lactotroph cells for subsequent electron microscopical antigen localisation. Ultra-thin sections were labelled with human anti-human prolactin followed by protein-A gold conjugate. Specific labelling was observed over secretory granules with a density of 15-30 particles per granule, as determined by the Quantimet 570 image analysis system. This technique provides a means of studying the pathophysiology of hormonal secretion at ultrastructural level and can be a useful tool in diagnostic and research investigations.

Epoxy Resins↗
PubMed1992

Comparison of the immune response of four different dosages of a yeast-recombinant hepatitis B vaccine in Singapore children: a four-year follow-up study.

The immunogenicity of four different dosages of yeast-derived hepatitis B vaccine (Merck, Sharp & Dohme: 0.6 micrograms, 1.25 micrograms, 2.5 micrograms and 5.0 micrograms), administered at 0, 1 and 6 months (0-1-6 schedule) intramuscularly, was evaluated in 122 seronegative healthy children 1-12 years of age. Three months after the first dose, 83.9-100% of the vaccinees seroconverted. Peak geometric mean titres (GMT) of between 1088 mlU/ml and 1699 mlU/ml were attained 3 months after completion of the vaccination schedule. After 24 months, anti-HBs (antibody to hepatitis B surface antigen) was detected in 93.1-100% of the vaccinees, but the GMT dropped to between 214.3 mlU/ml and 303.5 mlU/ml. After 48 months, 88.8-100% of the vaccinees continued to possess anti-HBs and 70.3-87% had titres above 10 mlU/ml. As expected, the GMT declined further to between 72.6 mlU/ml and 118.8 mlU/ml. There were no significant differences in seroconversion rates and GMT among the different dosage groups. All the vaccinees remained asymptomatic and free from hepatitis B virus infection. The study showed that reduced dosages of the vaccine (0.6 micrograms, 1.25 micrograms and 2.5 micrograms) were as immunogenic as the standard dose (5 micrograms); the 2.5-micrograms dose was recommended for the national childhood immunization programme in Singapore. No booster is necessary for at least four years after vaccination.

Antibody Formation↗
PubMed1979

The pathology of cartilage in chondrodysplasias.

The pathology of four types of chondrodysplasias, viz., type II achondrogenesis, thanatophoric dwarfism, Saldino-Noonan syndrome, and chondrodysplasia punctata were studied. In each of these disorders, cells with features similar to the chief and dark chondrocytes of normal hyaline cartilage were seen to be altered in different ways. There was a total absence of chief cells in type II achondrogenesis. All the chondrocytes present were of one variety at different states of maturation, with the fully matured cell having features of dark chondrocytes. The absence of chief cells was associated with marked diminution of interlacunar matrix and failure of growth plate development. The chief chondrocytes in thanatophoric dwarfism appeared diminished in number. They were probably abnormal functionally as evident by their lack of cytoplasmic vacuolation and the formation of thick, occasionally branched collagen in the matrix. The growth plate was stunted and poorly developed. Striking changes involving the dark cells were noted in Saldino-Noonan syndrome, where unusually elongated dark cells were found in groups within abnormal cystic spaces. The chief cells were large and contained abnormal cytoplasmic filaments. There was no formation of a growth plate. In chondrodysplasia punctata, the chief cells were enlarged and abnormally vacuolated. The matrix showed excessive aggregates of coarse granular material. In addition, there were focal accumulations of highly abnormal chief and dark cells with abnormal matrix which contained increased amount of keratan sulphate and culminated in spotty calcification.

Achondroplasia↗
PubMed1979

Phototherapy and neonatal liver function.

Two groups of 'healthy' full-term infants with hyperbilirubinemia exposed to phototherapy for 72 h demonstrated no significant change in serum glutamic pyruvic transaminase (SGPT), isocitric dehydrogenase (SICD), alkaline phosphatase (SAP), heat stable alkaline phosphatase (HSAP), total protein and albumin values; these values were similar to those of a comparable group of control infants without hyperbilirubinemia. The bilirubin levels, however, decreased significantly during this period. In a separate group of full-term infants with hyperbilirubinemia, the bromsulphalein (BSP) test before and after 72 h of phototherapy also demonstrated no signficant alteration; the results were comparable to a control group of infants. Phototherapy, even for a duration of 72 h apparently does not seem to affect liver function in infants with hyperbilirubinemia.

Alanine Transaminase↗
PubMed1978

Neonatal serum bilirubin levels in spontaneous and induced labour.

An investigation was made into the onset and severity of neonatal jaundice in 114 patients following spontaneous labour and labour induced by (a) amniotomy, (b) amniotomy and simultaenous infusion of oxytocin, (c) amniotomy and simultaneous administration of oral prostaglandin E2 (PGE2). No significant difference in serum bilirubin levels in the first five days of life was found in the four groups.

Bilirubin↗
PubMed1977

The nature of the dose-response relationship of phototherapy for neonatal hyperbilirubinemia.

The nature of the dose response relationship of phototherapy for neonatal hyperbilirubinemia was studied in 110 infants divided into ten comparable groups; each group was subjected to phototherapy of different intensity. The response to phototherapy increases with increasing dose, but the rate of this response progressively decreases with increasing radiance till a "saturation point" is reached, beyond which no further increase in response occurs to further increase in radiance, i.e., an asymptotic regression was demonstrated. The minimal radiance at which phototherapy begins to be effective for neonatal hyperbilirubinemia was also determined. The rebound after cessation of phototherapy was similar in all groups of infants, despite the shorter duration of exposure required for the groups subjected to intense phototherapy.

Bilirubin↗