Induced oxidative stress and cell death in the A549 lung adenocarcinoma cell line by ionizing radiation is enhanced by supplementation with docosahexaenoic acid.

Both ionizing radiation and docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid (PUFA), have been shown to inhibit tumor cell growth at least in part by increasing oxidative stress. In this study, the effects of ionizing radiation, DHA, or a combination of the two on cell proliferation, anchorage-independent growth, apoptosis, and lipid peroxidation in A549 lung adenocarcinoma cells were examined. In this study, significant decreases in cell proliferation and colony formation were noted for ionizing radiation or DHA treatments, whereas a combination of the two showed significant reductions over either treatment alone. Conversely, lipid peroxidation and apoptotic cell death showed significant increases with ionizing radiation and DHA treatments, whereas cells receiving both treatments demonstrated further significant increases. Moreover, addition of vitamin E, an antioxidant, was able to completely reverse lipid peroxidation and cell death due to ionizing radiation and partially reverse these changes in DHA treatments. Finally, the preferential incorporation of DHA into lung and xenograft compared to liver tissue is demonstrated in an in vivo model. These findings confirm the potential of DHA supplementation to enhance the treatment of lung cancer using ionizing radiation by increasing oxidative stress and enhancing tumor cell death.

Racial variation of factor VII activity and antigen levels and their correlates in healthy Chinese and Indians at low and high risk for coronary artery disease.

Plasma factor VII activity (FVIIc) is one of the independent risk factors of coronary artery disease (CAD) and is controlled by both genetic and environmental factors. South Asians including Indians have one of the highest prevalence and mortality rates from CAD while the Chinese have a much lower risk. Generally accepted risk factors cannot explain the high mortality from CAD in Indians. We examined two hundred and seventy seven Chinese (124 m, 153 f); and 216 healthy Indian (150 m, 66 f) adults for serum lipids; plasma FVIIc and FVIIag levels in order to examine racial variations of these and their correlates in these two populations. Both Indian men and women had significantly higher FVIIc levels (12% and 11%, respectively) than the Chinese even after adjustments of age, BMI and lipids (P < 0.01). In contrast, Indians had significantly lower plasma FVIIag levels than Chinese (8% and 9%, respectively in men and women; P < 0.01). Multiple linear regression analysis shows a strong correlation of FVIIc with serum triglycerides accounting for 4-8% of the total variability of FVIIc in different groups. Further, there was a stronger correlation between FVIIc and FVIIag in Indians than that in the Chinese (0.43 vs. 25) suggesting a greater activation resulting in higher FVIIc in Indians inspite of lower FVIIag levels. The higher FVIIc and stronger activation by triglycerides observed in this study partly explain the higher risk of CAD in Indians.

Serious head injuries from lawn darts.

Serious injuries secondary to lawn darts have not been reported. In this article two cases of penetrating skull injuries are reported. One patient developed a polymicrobial brain abscess necessitating surgical drainage and a prolonged hospitalization. Psychologic function was diminished at discharge. The second child required surgical repair of a depressed skull fracture. Thirteen lawn dart head injuries have been reported to the Consumer Product Safety Commission between 1983 and 1985. These injuries are summarized along with the reported cases to point out the seriousness (neurologic impairment in 5/10 head injuries) of such injuries and warn parents and physicians of the potential dangers of this game.

Lack of association of the dopamine D3 receptor gene polymorphism (BalI) in Chinese schizophrenic males.

Dopamine receptors have been implicated in the aetiology of schizophrenia and mode of action of antipsychotic drugs. A finding of increased homozygosity at the D3 receptor gene (BalI locus) has recently been reported. We have investigated the distribution of D3 receptor gene polymorphism (BalI) in 137 schizophrenic Chinese males and 125 healthy matched controls. The frequency of the rare allele was 0.30 and 0.31 in the patient and the control series. The distribution of genotypes in the patient series did not deviate significantly from Hardy-Weinberg equilibrium in the present series.

Role of adipose tissue in free fatty acid metabolism in hemorrhagic hypotension and shock.

This study was designed to observe the effects of hemmorrhage on the mobilization of free fatty acids from adipose tissue under a variety of experimental conditions. Experiments were conducted in fasting rabbits and dogs. A significant fall in arterial plasma free fatty acids was observed in rabbits following hemorrhage of 4 ml every 2 min and after inducing acute hemmorrhaged to a mean arterial blood pressure of 40 mm mercury. Adipose-tissue free fatty acids and arterial-plasma free fatty acids were simulatneously measured before and after hemorrhagic hypotension until death. Afterial free fatty acids fell significantly following hemorrhage, while the concentration of adipose-tissue free fatty acids rose significantly. In the next series of experiiments, dogs were pretreated with an alpha-receptor blocking agent phenoxybenzamine and acutely hemorrhaged. The results showed a significant rise in arterial free fatty acids concentration and an insignificant increase in adipose-tissue free fatty acids. These results suggest that hypoperfusion of adipose tissue plays an important role in the decreased supply of a major body fuel following hemorrhagic hypotension. The results are compatible with the view that metabolic fuel failure may be an important factor in the development of the complications of acute hemorrhage and suggest the concept that adipose tissue may be an important target organ in hemorrhagic shock.

DNA amplification by the polymerase chain reaction for the rapid diagnosis of tuberculous meningitis. Comparison of protocols involving three mycobacterial DNA sequences, IS6110, 65 kDa antigen, and MPB64.

DNA amplification of three Mycobacterium tuberculosis-specific DNA sequences by the polymerase chain reaction (PCR) were evaluated as a means for rapid diagnosis of tuberculous meningitis (TBM). The DNA sequences amplified were a 123 bp region of the IS6110 insertion elements which occur in multiple copies in the mycobacterial genome, a 240 bp region (nts 460-700) from the MPB 64 protein coding gene, and the 383 bp region of the 65 kDa heat shock protein (HSP) antigen. Twenty-seven cerebrospinal fluid (CSF) specimens were studied. Six were obtained from patients with TBM diagnosed by culture (4/6) or by the patients' response to anti-tuberculous therapy (2/6). The remaining 21 specimens were obtained from patients with febrile seizures (3/21), aseptic meningitis (3/21), septic meningitis (14/21), and cryptococcal meningitis (1/21), and these served as negative controls. Our results indicate that although the protocols involving the 3 DNA sequences were able to detect TB DNA in the 6 TBM specimens, the main drawback was their extreme sensitivity, thus giving rise to false positive results. In particular, the repeat copy sequence, IS6110, and the 65 kDa HSP gave unacceptably large numbers of false positive results (62% and 33%, respectively).

Malignant eccrine spiradenoma. Case report and review of the literature.

Malignant eccrine spiradenoma is an exceedingly rare tumor. A case of a 72-year-old women with this highly aggressive malignancy arising from a long-standing lower leg lesion is reported. Management during the course of disease included surgery, radiation therapy (RT), hyperthermic limb perfusion chemotherapy, and chemotherapy. The patient died of her disease, with widespread metastatic disease 20 months after the diagnosis. A review of the literature is presented, and treatment considerations are summarized.

Apolipoprotein H polymorphism and serum lipoprotein and apolipoprotein levels in two Asian populations.

The apolipoprotein H (apo H) is a constituent of several lipoprotein particles and, therefore, may play an important role in lipid metabolism. In this study, we have investigated the role of common apo H structural polymorphism in determining serum total cholesterol; high-density lipoprotein cholesterol; triglycerides; and apolipoproteins A-I, A-II, and B in 655 Chinese and 126 Dravidian Indians from Singapore. Serum lipoprotein and apolipoprotein levels were adjusted for significant concomitant variables for age and body mass index, and the quantitative mean values between different apo H genotypes were compared by an analysis of covariance. The distributions of serum lipoprotein and apolipoprotein levels were found to be comparable between the three common apo H genotypes in both ethnic groups, indicating that the apo H polymorphism may not play a significant role in lipid metabolism.

Reliability of transcutaneous oxygen monitoring of critically ill children in a general pediatric unit.

While transcutaneous continuous monitoring of partial pressure of oxygen (TcPO2) is a proven valuable diagnostic tool in intensive care of sick neonates, its use in older children is less well defined. The purpose of this study is to establish the accuracy and reliability of TcPO2 as a reflection of arterial partial pressure of oxygen (PaO2) in critically ill pediatric patients. Twenty-six children, age ranging from 4 days to 13 years, were studied. The main diagnostic categories were cardiac 54 per cent, respiratory 27 per cent, gastrointestinal 15 per cent, and neurologic 4 per cent. Forty three estimations of PaO2 (by radial arterial sampling) and TcPO2 (by cutaneous monitor) were obtained simultaneously. Their correlation coefficient, regression equation, and confidence limits were calculated by standard statistical methods with the aid of a microcomputer. Our data show that the high degree of correlation between TcPO2 and PaO2 is highly significant (r = 0.90, p less than 0.001) for the full range of PaO2 between 0 to 200 mm Hg. At the lower range of PaO2 (0-79 mm Hg), the degree of correlation (r = 0.91, p less than 0.001) is better than that (r = 0.77, p less than 0.001) at the higher range (80-200 mm Hg), although the difference between the two correlation coefficients is not significant (p greater than 0.05). It is important to note that TcPO2 consistently underestimates the PaO2 and the 95% confidence limits are rather wide. We conclude that TcPO2 is a reasonably accurate reflection of PaO2 in critically ill pediatric patients. Its main advantage is in predicting and showing trends in tissue oxygenation by noninvasive means. However, when critical assessment of the degree of hypoxemia is required, TcPO2 is no substitute for PaO2.

Ultrasonic systolic blood pressure gradient between upper and lower limbs in normal term Chinese neonates.

The determination of a normal pattern of systolic blood pressure (SBP) gradient between upper limbs (UL) and lower limbs (LL) in neonates is important in the diagnosis of the coarctation syndrome. The scarcity of studies of normal neonates and the conflict of opinion prompted us to evaluate this problem. The UL and LL systolic blood pressures of 100 normal term Chinese neonates were measured by the Doppler Ultrasonic method (Roche Arteriosonde 1020). Under resting condition, the majority (89%) of our neonates had a negative SBP gradient (LL greater than UL). The mean LL SBP (70.1 mmHg) was significantly higher than that of the UL (59.5 mmHg), p less than 0.001. Eleven out of 100 of our neonates had a positive (UL greater than LL) SBP gradient. Eight of these were less than 1 week old. None had a positive gradient of more than 20 mmHg. According to the results of our study, during the first week of life, normal neonates may have upper limb pressure greater than lower limb of up to 20 mmHg.

The diagnosis of tuberculous meningitis using the polymerase chain reaction.

AIM: DNA amplification by the polymerase chain reaction (PCR) was evaluated as a means for rapid diagnosis of tuberculous meningitis (TBM). METHODS: A 240 bp region (nts 460-700) from the MPB 64 protein coding gene specific for Mycobacterium tuberculosis (TB) was selected for amplification. Nineteen clinical samples were studied. Six were obtained from patients with TBM diagnosed by culture (4/6) or by response to therapy (2/6). The remaining 13 samples were obtained from patients with febrile seizu es (8/13), aseptic meningitis (3/13) and septic meningitis (2/13), and these served as negative controls. RESULTS: We detected TB DNA in all the 6 CSF specimens obtained from patients with TBM. PCR alone was sufficient to detect TB DNA in 5 of these 6 samples. However, one sample was positive only when PCR was followed by oligonucleotide hybridisation. In the 2 patients whose CSF were obtained only after commencement of TB therapy, TB cultures were negative but positive on PCR nd oligoprobe labelling. The diagnosis of TBM was confirmed based on their remarkable response to therapy. Twelve of the thirteen negative controls were TB DNA negative. There was one false positive sample, which was thought to be due to TB DNA contamination. CONCLUSION: Taken together, our results indicate that DNA amplification using PCR, followed by oligonucleotide hybridisation offers a rapid (5 working days) means of diagnosis of TBM, provided care is taken to ensure that cross contamination of DNA samples is avoided.

Medical genetics in Singapore.

This paper is a brief review of the scope of research and clinical work in human genetics in Singapore. Clinical genetics and karyotyping were established in the early sixties. G6PD deficiency was discovered then as the commonest cause of kernicterus in the newborn. Screening of all newborns was instituted. The measures taken have been very successful and kernicterus is virtually unknown since the early 1970s. Numerous G6PD variants have been discovered and characterized. During the 1980s the emphasis shifted to molecular genetics. Work on the molecular genetics of alpha- and beta-thalassemias, Duchenne muscular dystrophy, hemophilia and retinoblastoma have been established, and good progress on diseases such as neurofibromatosis, leukemias, and lymphoid malignancies. The diagnosis of tuberculosis by DNA amplification (PCR) has been successfully implemented. Numerous papers have been published on the molecular genetics of coronary artery disease, as well as in population genetics.

Usefulness of dinucleotide polymorphism markers in genetic analysis of Duchenne's muscular dystrophy cases in Singapore.

Dinucleotide polymorphisms are short tandem repeat sequences that can be used as probes for haplotype analysis in Duchenne's muscular dystrophy (DMD). There are approximately a total of 50,000 to 100,000 such loci in the human genome, and they are highly informative due to the variability of allele lengths at these loci. Primers can be designed to amplify across such repeats located in the dystrophin gene to provide diagnostic information when RFLP analysis is uninformative. We report the usefulness of three such loci for analysis of DMD families in Singapore. The STR50 marker consists of (CA)n repeats located in intron 50 of the dystrophin gene while DYS1 marker is located upstream to the transcriptional start site for the brain dystrophin promoter and BSTRH marker is identified in the 3' untranslated region of the gene. End-labeled PCR products were resolved on 6% denaturing polyacrylamide sequencing gel. Alleles were identified by comparison with sequencing markers. PCR product typically ranged between 174 bp to 255 bp with five to six alleles observed. The heterozygosity rates estimated from 50 X chromosomes of unrelated individuals were 76.0% (BSTRH), 86.6% (DYS1) and 93.3% (STR50). In 38 DMD families studied, the results obtained show that these markers were highly informative and reveal Mendelian mode of inheritance. They were useful for linkage analysis, identification of deletion mutations, confirmation of paternity and mapping of gene recombination.

Molecular analysis of Hb Q-H disease and Hb Q-Hb E in a Singaporean family.

Hb Q (alpha 74Asp-His) results from a mutation in the alpha-gene such that abnormal alpha Q-chains are synthesized. The alpha Q-chains combine with the normal Beta A-chains to form abnormal Hb alpha 2Q beta 2A (Hb Q). Hb Q-H disease is rare, and has been reported only in the Chinese. We report here a Chinese family, were the mother diagnosed with Hb Q-H disease and the father with Hb E heterozygosity and a child with Hb Q-E-thalassemia. Thalassemia screening of the mother's blood revealed a Hb level of 6.8g/dl with low MCV and MCH. Her blood film was indicative of thalassemia. Cellulose acetate electrophoresis showed Hb H and Hb Q with the absence of Hb A. Globin chain biosynthesis was carried out and alpha Q- and beta-chains were detected. Normal alpha- chains were absent. Digestion of the mother's DNA with Bam HI and Bgl II followed by hybridization with the 1.5 kb alpha-Pst probe showed a two alpha-gene deletion on one chromosome and the -alpha Q chain mutant with the -alpha 4.2 defect on the other chromosome. DNA amplification studies indicated the two-gene deletion to be of the -SEA/ defect. The patient was concluded to possess Hb Q-H disease (--SEA/-alpha 4.2Q). Cellulose acetate electrophoresis of the father's blood showed the presence of Hb A, F and E. Molecular analysis of the father's DNA confirmed an intact set of alpha-genes (alpha alpha/alpha alpha). Globin chain biosynthesis of fetal blood of their child showed gamma, beta A, beta E, alpha A and alpha Q-chains. Molecular analysis of the child's DNA showed one alpha-gene deletion, thus giving a genotype of alpha alpha/-alpha 4.2Q beta beta E.

Glucose-6-phosphate dehydrogenase deficiency in Singapore.

Glucose-6-phosphate dehydrogenase (G6PD) in man is an X-linked enzyme. The deficiency of this enzyme is one of the most common inherited metabolic disorders in man. In Singapore, three clinical syndromes associated with G6PD deficiency had been described: severe haemolysis in neonates with kernicterus, haemoglobinuria and "viral hepatitis"-like syndrome. The human G6PD monomer consists of 515 amino acids. Only the tetrameric or dimeric forms composed of a single type subunit are catylitically active. The complete amino acid sequence of G6PD had been elucidated in man and various other animals. The region of high homology among the enzymes of various animals is presumably functionally active. Among the Chinese in Singapore, three common molecular variants had been identified: Canton (nt 1376 G --> T), Kaiping (nt 1388 G --> A) and Mediterranean (nt 563 C --> T) in frequencies of 24%, 21% and 10% respectively. In addition, two common mutants (Gaozhou, nt 95 A --> G and Chinese 5, nt 1024 C --> T) have been detected in Singapore Chinese in low frequencies. In Malays, 6 different deficient variants are known in Singapore (3 new, 1 Mahidol, 1 Indonesian and 1 Mediterranean).

Plasma lipids and lipoprotein(a) levels in the Chinese from China and Singapore.

This study compared the influence of environmental factors on plasma lipid levels between the descendants of immigrant southern Han Chinese (Singapore Chinese, n = 275) and the native Chinese from southern China (n = 277). Their lipid profiles including lipoprotein (a) [Lp(a)] were measured and compared. The alpha level was set at 0.05 throughout the analysis. Body mass index (BMI), plasma total cholesterol (TC), low density lipoprotein cholesterol (LDLC), high density lipoprotein cholesterol (HDLC) and triglycerides (TG) levels were significantly elevated in the Singapore Chinese. Plasma Lp(a) however, was comparable in both groups for concentrations as well as frequency distributions. Since both groups were genetically identical, the similar Lp(a) level was in agreement with studies which reported that the apolipoprotein(a) [apo(a)] gene explained as much as 70% of the plasma Lp(a) variations in Chinese. No correlation of plasma Lp(a) level was observed with age and BMI while significant positive linear correlations were observed with TC and LDLC in the male subjects only. We concluded that environmental factors (possibly affluent lifestyle and westernised diet) have significantly influenced the lipid risk factor levels of the Singapore Chinese whereas Lp(a) levels, which are predominantly under genetic control, were not altered significantly.

Automated blood pressure reading--its claims and its reliability.

Advances in technology have made available automated devices for rapid and easy measurements of arterial blood pressure. This study evaluates the performance of one such device, the Hitachi Digital Blood Pressure and Pulse Monitor, Model HME-20, against a standard mercury sphygmomanometer, the Accoson . Fifty four sets of systolic and diastolic readings were simultaneously obtained using the two instruments. The readings obtained by both methods correlated significantly with each other (p less than 0.001). However, the mean diastolic pressure obtained by HME-20 is significantly lower than that obtained by the Accoson (p less than 0.05). There is also a consistent underestimation of systolic and diastolic pressures of 8 mm Hg by HME-20. Moreover, linear correlation studies between HME-20 and Accoson readings reveal that the 95% confidence limits are fairly wide, which limit, therefore, the value of a single reading by HME-20. Our preliminary evaluation suggests that HME-20 is more suited to monitor the trend of blood pressure changes rather than to provide precise determination of arterial blood pressures.

Percutaneous transluminal balloon valvuloplasty: the treatment of choice for congenital valvar pulmonary stenosis.

Forty-eight children with suspected isolated pulmonary valvar stenosis were evaluated clinically and echocardiographically between January 1987 and December 1988. Fourteen patients with significant transpulmonary peak systolic pressure gradient greater than 30 mmHg on continuous-wave Doppler interrogation were subjected to right heart catheterisation. Percutaneous transluminal balloon valvuloplasty was performed in 11 of these patients with peak systolic pressure gradient than 40 mmHg across the pulmonary valve at cardiac catheterisation. Satisfactory reduction of systolic right ventricular pressure (110 +/- 43 to 46 +/- 17 mmHg, p less than 0.001) and peak systolic pressure gradient across pulmonary valve (92 +/- 44 to 27 +/- 16 mmHg, p less than 0.001), were achieved in all cases. The reduction of peak systolic pressure gradient (64 +/- 37 mmHg, range = 29-158 mmHg), was positively correlated with the initial right ventricular systolic pressure (r = 0.92, p less than 0.0002). There was no significant complication in this series and all patients were discharged the day after the procedure. Percutaneous transluminal balloon valvuloplasty is effective and safe. It should be the treatment of choice for significant valvar pulmonary stenosis in children.

Transcutaneous estimation of oxygen tension in unusual clinical situations.

Transcutaneous oxygen monitoring has been used successfully in the assessment of trend in tissue oxygenation in neonates and children. This study highlights the application of transcutaneous oxygen monitoring in three unusual clinical situations: dual channel oxygen monitoring in persistent foetal circulation, hyperoxia test in the differentiation of cardiac or pulmonary central cyanosis and the effect of endotracheal intubation on tissue oxygenation. Its usefulness and potential application in these situations are discussed.

Normal standards of in vitro induced platelet aggregation.

Measurement of in vitro induced platelet aggregation by turbidimetric method is a very important investigative tool when patients are evaluated for bleeding diasthesis due to possible underlying platelet functional disorders. As commercial controls are not available, it is important that each laboratory establishes its own normal pattern of platelet aggregation induced by standard aggregating agents. The aggregation curves in terms of maximal % aggregation, Vmax and lag time in 50 normal Chinese controls are reported. The final concentrations of the aggregating agents used, namely adenosine diphosphate, adrenaline, collagen and ristocetin, are 20 microM, 10 microM, 0.2 mg/ml and 1.0 mg/ml, respectively. 20% of the controls had either no aggregation or only primary aggregation with adrenaline. Lag time by collagen-induced aggregation is significantly longer, but other parameters of platelet aggregation by adenosine diphosphate, adrenaline and collagen in Chinese are comparable to one reported control study. The maximal % aggregation induced by ristocetin in Chinese does not differ significantly from the reported values in whites but is significantly higher than in Blacks at a concentration of 1.0 mg/ml. Interpretation of platelet aggregometry in patients with bleeding tendency should be based on the normal patterns established from a group of normal controls in each laboratory rather than by comparison with a single control alone.