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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↗
PubMed1991

Bronchopulmonary dysplasia in very low birthweight infants.

The incidence, clinical presentation and severity of bronchopulmonary dysplasia (BPD) in 110 consecutive very low birthweight (VLBW) infants admitted to the National University Hospital Neonatal Intensive Care Unit between October 1985 and January 1989 is reviewed. Thirty-two infants died, giving an overall survival rate of 70.9%. Sixty infants (54.4%) required mechanical ventilation in the first week of life; 24 (40%) of these infants died. Of the 36 survivors, 23 required oxygenation at 28 days of life and 21 fulfilled the criteria for BPD (35% of the 60 ventilated and 58% of the survivors). The incidence of BPD in all VLBW infants is 19% and of VLBW survivors 27%. Birthweight and gestational age appear to be important determinants. All the survivors in the 501-750 g birthweight group developed BPD compared to 6.25% in those above 1250 g. None of those greater than 30 weeks gestation developed BPD. Two forms of BPD were observed; the 'severe' group presented radiologically with chest radiographs characteristic of Stage IV BPD, while the 'mild' group with small or normal sized lungs demonstrated irregular strands of radio-densities alternating with areas of normal or increased lucency. The duration of mechanical ventilation and oxygen dependency were significantly longer in the 'severe' group, with the mean maximum peak inspiratory pressure, mean airway pressure, and FiO2 required in the first week of life being also significantly higher. Hyaline membrane disease was the main cause of respiratory failure requiring ventilation. The other causes were persistent pulmonary hypertension (1) and apnoea of prematurity (3); all of the latter developed only mild BPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Weight↗
PubMed1991

Effect of blood transfusion on acid base, glucose and electrolyte status in very low birth weight infants.

The effect of citrate phosphate dextrose (CPD) blood transfusion on the acid base, glucose and electrolyte status of VLBW infants was studied in infants aged 1-7, 8-20 and greater than 20 days; a 4th group composed of infants greater than 20 days subjected to a second transfusion was also studied. All the infants remained clinically well during and after the transfusion. Only the infants in the group 1-7 days experienced a significant fall in ionic Ca and PO2. No significant change in all the other parameters studied was observed. In the other groups of infants studied, the changes observed were not significant, and became less with increasing age and repeat transfusion. VLBW infants apparently tolerate CPD blood transfusion well.

Acid-Base Equilibrium↗
PubMed1991

High frequency oscillatory ventilation in neonates with respiratory distress.

High frequency oscillatory ventilation (HFOV) was attempted in ten infants with severe respiratory failure not responding to conventional ventilation (CV); it was, therefore, used as a rescue measure. HFOV was successful in improving the respiratory status of seven infants, all with hyaline membrane disease (HMD). Five of these infants survived, of the remaining two, one died of massive peri/intra-ventricular haemorrhage and the other of cholestasis associated with total parenteral nutrition. It was unsuccessful in three infants, one with meconium aspiration, the second died within two hours commencing HFOV and the third with severe depression and hypotonia.

Blood Gas Analysis↗
PubMed1991

Drug therapy of the fetus and neonate.

The fetus and neonate are very sensitive and delicate. Events occurring during this period can therefore, have a very significant influence on later life. Drugs given to the pregnant women may have a significant impact on the fetus, as the thalidomide disaster has shown. Drug therapy of the fetus via the mother has also been proven to be effective in certain situations, especially with regard to improving lung maturity. With advances in visualisation of the fetus by ultrasonography, direct fetal treatment has been successfully performed. The neonate immediately after delivery is in a very precarious state, especially if premature. Drug therapy is sometimes indicated then to ensure his well-being. Such drug therapy will have to take into consideration absorption problems in relation to a prolonged gastrointestinal transit time as well as hepatic and renal immaturity, together with a relatively greater volume of distribution of the drug (Vd). When these considerations are taken into account, effective therapy can be instituted with successful results. Drug treatment for specific conditions in the premature baby, when tailored to their needs and limitations, have indeed been successful.

Drug Administration Routes↗
PubMed1991

Phototherapy for neonatal jaundice.

Phototherapy is now the preferred method of treatment for neonatal hyperbilirubinemia by virtue of its noninvasive nature and its relative freedom from major complications. It is also convenient, easy to use, and inexpensive in terms of personnel, equipment, and disposals. Long-term experience with phototherapy has demonstrated its safety as well as efficacy. With high-intensity phototherapy at saturation dose, even severe hemolytic hyperbilirubinemia can be adequately controlled; only pack-cell transfusions are required to correct the resulting anemia. It should be stressed, however, that adequate monitoring of the well-being of the baby together with the bilirubin levels should always be observed carefully. The lamps should be kept cool during phototherapy and be changed regularly after every 2000 hours of use. Observing such precautions will ensure the efficacy and safety of phototherapy.

Age Factors↗
PubMed1990

A multivariate analysis of factors predictive of parenteral nutrition-related cholestasis (TPN cholestasis) in VLBW infants.

To identify the factors predictive of development of TPN-related cholestasis, we conducted a historical cohort analysis of 62 VLBW infants who received TPN of which 17 developed cholestasis (27.4%). In the cholestatic group, the mean duration of TPN administration was significantly longer (25.7 days vs 8 days, p less than 0.001), the maximum daily amino-acids and lipids in the TPN infusate was significantly higher (amino-acids 2.25 vs 1.25 gm/kg/day, p less than 0.001; lipids 2.0 gm/kg/day vs 1.25 gm/kg/day, p less than 0.01), the duration of fasting was significantly longer (20.7 days vs 6.3 days, p less than 0.001) and the incidence of necrotizing enterocolitis was significantly higher (58.8% vs 15.5%, p 0.02). Using a linear discriminant analysis model with development of cholestasis as the dependent variable, the duration of TPN (p 0.0000) and the maximum daily amino-acid in infusate (p 0.0000) were found to be independent variables predictive of development of cholestasis. This model may serve to identify VLBW infants who will develop cholestasis during TPN.

Amino Acids↗
PubMed1989

Efficacy of fluorescent daylight, blue, and green lamps in the management of nonhemolytic hyperbilirubinemia.

The efficacy of fluorescent daylight, green, and blue lamps in reducing bilirubin levels was compared in two groups of infants with nonhemolytic hyperbilirubinemia: healthy infants in a term nursery and infants in an intensive care unit. The decline of serum bilirubin concentration was most rapid with the blue lamps, with the duration of exposure required being significantly shorter than that with the other two types of light in both groups. The rate of decline over the first 24 hours, as well as the overall rate of decline for the whole duration of phototherapy, was also significantly greater with the blue lamps, the rate being about twice that for the green lamps in the infants in the intensive care unit; the daylight lamps were intermediate in efficacy. The daylight lamps permitted easy clinical monitoring with minimal side effects, whereas the green and blue lamps were equally disturbing to the attending personnel. The green lamps caused severe erythema and tanning in the initial 200 hours of phototherapy. It appears preferable to use either daylight lamps, which permit enhanced clinical monitoring with adequate efficacy, or special blue lamps, which provide maximal therapeutic effect, rather than green lamps, which offer neither.

Erythema↗
PubMed1989

The hepatitis B immunization programme in Singapore.

A voluntary immunization programme to prevent perinatal transmission of hepatitis B virus (HBV) infection in Singapore was implemented on 1 October 1985 as an integral component of the national childhood immunization programme. Up to April 1988, a total of 68,845 mothers who attended government maternal and child health clinics were screened for the disease. Of these, 2432 (3.5%) were positive for hepatitis B surface antigen (HBsAg) and 904 (1.3%) for hepatitis B e antigen (HBeAg). Virtually all the babies born to carrier mothers completed the full immunization schedule; and in addition, those of HBeAg-positive mothers were given a dose of hepatitis B immunoglobulin at birth. The hepatitis B immunization programme was extended on 1 September 1987 to cover all newborns. About 90% of the 15,943 babies delivered in government institutions from September 1987 to April 1988 were immunized at birth, with the subsequent doses being administered at maternal and child health clinics at 4-6 weeks and 5 months later. More than 85% of the children given the full course of plasma-derived and yeast-derived hepatitis B vaccine from birth continued to have protective antibody to HBV two years after immunization. The programme is being closely monitored to assess the duration of immunity and the need for booster doses, while seronegative adults are also being encouraged to be vaccinated.

Adolescent↗
PubMed1989

The prevalence of unilateral mastication in a non-patient population: a pilot study.

One hundred and twenty-seven dental undergraduates participated in a questionnaire survey containing questions relating to their experience with craniofacial pain, jaw function, oral habits and other predisposing factors. The prevalence of chronic habitual unilateral chewers (10%) in the above selected non-patient population was significantly lower than that reported in the patients suffering from craniomandibular disorders (CMD). Lateral masticatory preference was also shown to be significantly associated with symptoms such as "noises from the joints", "difficulty in opening the mouth wide", "an uncomfortable bite", "neckpains", "soreness in the teeth", "painful cheek muscles", "pain in the temples" and/or "tension in the muscles of the face and jaws". The interrelationship between unilateral mastication and CMD is discussed.

Adult↗
PubMed1989

Management of neonatal jaundice.

Neonatal jaundice is the commonest complication among newborn infants in Singapore. Treatment is only required when the jaundice becomes severe. The trans-cutaneous bilirubinometer is useful in screening for neonatal jaundice; it is fairly reliable at levels less than or equal to 200 mumol/l in fullterm babies. Phototherapy is the commonest form of treatment and is effective in almost all cases if high intensity phototherapy is also used. Exchange transfusion is now only rarely used in view of its known complications and relatively high mortality rate.

Exchange Transfusion, Whole Blood↗
PubMed1989

Clinical experience with phototherapy.

Clinical experience with phototherapy in 3,999 infants with non-haemolytic hyperbilirubinaemia and 427 infants with hyperbilirubinaemia associated with G6PD deficiency is presented. For non-haemolytic hyperbilirubinaemia, phototherapy was extremely effective in extremely preterm infants with very low birth weight (gestation less than or equal to 32 weeks, birth weight less than or equal to 1,500 gm) and least effective in full term infants with very low birth weight (gestation greater than 37 weeks, birth weight less than or equal to 1,500 gm) and large preterm infants (gestation less than 37 weeks, birth weight greater than 2,270 gm). The failure rate of phototherapy for non-haemolytic hyperbilirubinemia was only 2.00/1,000 infants. The bilirubin rebound was usually mild; repeat phototherapy was required in only 30 infants (7.50/1,000) with the response to the second exposure comparable to that of the first. No infant required a third exposure. Phototherapy was effective in reducing bilirubin levels in hyperbilirubinaemia associated with G6PD deficiency, the effectiveness being, however, less than in babies with non-haemolytic hyperbilirubinaemia (G6PD normal status). There was no failure in this group of babies. Only a small proportion of infants required a second exposure (4.68/1,000). All the infants tolerated phototherapy well with none developing any illness that could be attributed to the exposure. This clinical experience demonstrates that phototherapy is effective and safe for the treatment of non-haemolytic hyperbilirubinaemia or hyperbilirubinaemia associated with G6PD deficiency.

Bilirubin↗