Twenty authentic steroids, derivatized as O-methyl oximes (MO), trimethylsilyl (TMS) ethers or as MO-TMS ethers have been subjected to capillary gas chromatography using two different columns. Virtually all of the steroid derivatives have been resolved, one difficult pair to separate being 5,16-androstadien-3 beta-ol and 5 alpha-androst-16-en-3 beta-ol on the non-selective phase OV-1. Where syn and anti forms of MO derivatives arose, these were also resolved under the conditions utilised. This technique of 'steroid profiling' has been applied to the separation and quantification of metabolites of pregnenolone which were formed during incubations of the microsomal and cytosolic fractions from rat testes. The majority of the metabolites were found in the microsomal incubation. These compounds included some odorous 16-androstenes as well as other C21 and C19 steroids, the formation of which was consistent with the 5-ene and 4-ene pathways of testosterone biosynthesis being operative. In addition, evidence was obtained for 16 alpha-hydroxylation of C21 steroids. Very much less metabolic activity was found in the cytosolic fraction of rat testes. Metabolic pathways have been proposed which both confirm and extend earlier work. We conclude that the rat testis can only form some of the odorous, possibly pheromonal, 16-androstenes and that these are quantitatively less important than in the porcine testis.
Lung capacity and maximum oxygen uptake (VO2max) were measured directly in 167 healthy males, from all the main races in Malaysia. Their ages ranged from 13 to 59 years. They were divided into five age groups (A to E), ranging from the second to the sixth decade. Lung capacities were determined using a dry spirometer and VO2max was taken as the maximum rate of oxygen consumption during exhaustive exercise on a cycle ergometer. Mean forced vital capacity (FVC) was 3.3 +/- 0.5 l and it correlated negatively with age. Mean VO2max was 3.2 +/- 0.2 l.min-1 (56.8 +/- 3.5 ml.kg-1.min-1) in Group A (13-19 years) compared to 1.7 +/- 0.2 l.min-1 (28.9 +/- 2.9 ml.kg-1.min-1) in Group E (50-59 years). Regression analysis revealed an age-related decline in VO2max of 0.77 ml.kg-1.min-1.year-1. Multiple regression of the data gave the following equations for the prediction of an individual's VO2max: VO2max (l.min-1) = 1.99 + 0.035 (weight)-0.04 (age), VO2max (ml.kg-1.min-1) = 67.7-0.77 (age), where age is in years, weight in kg. In terms of VO2max as an index of cardiopulmonary performance. Malaysians have a relatively lower capacity when related to the Swedish norms or even to those of some Chilean workers. Malaysians were, however, within the average norms of the American Heart Association's recommendations. Age-related decline in VO2max was also somewhat higher in the Malaysians.
The nutritional status of 641 children between the ages of 0 to 4 years old, from 835 households in 41 randomly selected rural villages with water supply in Sarawak were determined. Based on Waterlow's classification and the National Center for Health Statistics (NCHS) standards, 61% of the children were stunted and 44.1% were wasted. Based on Gomez's classification and the NCHS standards 81.9% of the children were malnourished. There was no sex difference in nutritional status. The percentage of malnourished children increased continuously with age while the percentage of children who were wasted increased from 6 to 36 months and then it leveled off. The percentage of stunted children also increased with age but the increase was sharpest in children who were 12 to 23 months old. It is noted that the Gomez classification overestimates the prevalence of undernutrition.
Fish has been known as a source of nonoccupational mercury exposure to fish-consuming population groups. In this study, hair samples collected from fishermen and their families residing in an industrialized area in Penang and a nonindustrialized area in Terengganu were analyzed for mercury by neutron activation. The range, arithmetic mean, geometric mean, and median of the mercury concentrations for the groups in Penang and in Terengganu were 0.45-16.68, 3.61, 3.49, and 2.96 and 6.79-18.31, 12.08, 11.69, and 12.05 mg/kg, respectively. Somewhat lower values than from the Penang group were found in a group from Selangor consisting mainly of office workers. The group in Penang took about 40-100 g of fish/d, whereas the group in Terengganu consumed twice as much. This shows that hair mercury levels depend on a fish consumption pattern, and not on the location of the population. The levels of mercury found in this study were similar to those reported by other workers for fish-consuming population groups worldwide.
For the diagnosis of IgE-mediated (immediate) hypersensitivity to natural rubber latex (NRL), skin prick testing with extracts of latex gloves has been widely used, but such extracts are difficult to standardize. The present study aimed to produce on an industrial scale an NRL extract from freshly collected NRL and to evaluate, calibrate, and standardize the extract by both in vivo and in vitro testing. The source material, latex of the rubber tree, Hevea brasiliensis (clone RRIM 600), was frozen immediately after collection in Malaysia and shipped in dry ice to Stallergènes SA, France. Protein and allergen profiles were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting, isoelectric focusing (IEF), crossed immunoelectrophoresis (CIE), and crossed radioimmunoelectrophoresis (CRIE). Allergen quantification was effected by RAST inhibition. The capacity of the preparation to elicit immediate hypersensitivity reactions in vivo was measured by skin prick testing in 46 latex-allergic patients and 76 nonallergic control subjects. SDS-PAGE and immunoblot profiles of the extract and an NRL standard (E8) provided by the US Food and Drug Administration were almost identical, disclosing several distinct IgE-binding proteins with apparent molecular weights of 14, 20, 27, 30, and 45 kDa, conforming to reported molecular weights of several significant NRL allergens. An arbitrary index of reactivity (IR) of 100 was assigned to the extract at 1:200 dilution (w/v), having a protein content of 22 micrograms/ml. Skin prick testing of latex-allergic patients and controls using the extract at 100 IR revealed 93% sensitivity, 100% specificity, 100% negative predictive value, and 96% positive predictive value. In conclusion, a skin prick test reagent for diagnosis of type I NRL allergy was successfully standardized. The reagent was demonstrated to contain most, if not all, of the currently known clinically significant NRL allergens, and it showed high sensitivity and specificity.
An analytical method using HPLC with UV detection was developed to investigate the quassinoid content of Eurycoma longifolia Jack (Simaroubaceae) collected from various sources. Eurycomanone (1), longilactone (2), 14,15beta-dihydroxyklaineanone (3), 15beta-acetyl-14-hydroxyklaineanone (4), 6alpha-hydroxyeurycomalactone (5), and eurycomalactone (7) were isolated as reference standards and together with the synthesized 1beta,12alpha,15beta-triacetyleurycomanone (6, internal standard), were identified by NMR, MS, UV and IR spectroscopies. Their coefficient of variation values for 0.50-35 microg ml(-1) concentrations of quassinoids and their retention times measured within- and between-day were small. The recoveries of the spiked quassinoids in E. longifolia samples and their detection limits at 8.5 times signal to noise ratio were 99.75-109.13% and 0.01 microg ml(-1), respectively. From the root samples analysed, 1 had the highest concentration, being about 16.8-39.6 fold higher than the other quassinoids 2, 3, 5, 7 but 145.3 fold higher than 4 which showed the lowest concentration.
Saliva collection is non-invasive and less stressful when compared with blood collection. Extensive studies on saliva has been carried out and the use of saliva as a biological sample in clinical diagnosis and for monitoring hormones, drugs and pollutants and viruses has been recommended. The complexities associated with saliva such as proper collection device and strict standardisation of a number of factors which include time of collection, types of saliva and storage made it less favourable to blood.
This paper focuses on the evaluation of the k0 method of instrumental neutron activation analysis in biological materials. The method has been applied in multielement analysis of human hair standard reference materials from IAEA, No. 085, No. 086 and from NIES (National Institute for Environmental Sciences) No. 5. Hair samples from people resident in different parts of Malaysia, in addition to a sample from Japan, were analyzed. In addition, human kidney stones from members of the Malaysian population have been analyzed for minor and trace elements. More than 25 elements have been determined. The samples were irradiated in the rotary rack (Lazy Susan) at the TRIGA Mark II reactor of the Malaysian Institute for Nuclear Technology and Research (MINT). The accuracy of the method was ascertained by analysis of other reference materials, including 1573 tomato leaves and 1572 citrus leaves. In this method the deviation of the 1/E1+ alpha epithermal neutron flux distribution from the 1/E law (P/T ratio) for true coincidence effects of the gamma-ray cascade and the HPGe detector efficiency were determined and corrected for.
An activity supportive of the MOH QA Programme, the National EQAS for clinical chemistry monitors for analytical performance in core routine biochemical testing by the pathology laboratories, with unsatisfactory performance scores serving to alert against deficiencies or problems and the scores in subsequent challenges providing the feedback of effectiveness of remedial actions taken. While unacceptable individual analyte performance score (variance index score, VIS) indicated problems in instruments, reagent and calibrators, or the use of inherently poorer methods, repeated occurrence of unsatisfactory OMRVIS was traceable to generally poor laboratory management of usually inadequately-equipment small laboratories. The outcome has been one of slow but gradual improvement in the overall performance of participating laboratories, with a move towards methods upgrading and standardization to achieve greater concordance of results. Presently, the programme is limited to 61 government and 4 private hospital laboratories in the country for 12 commonly assayed clinical biochemistry analytes. It is hoped that the NEQAS could be extended to the other private laboratories and that of academic institutions. However, this is dependent to a large extent on the manpower and financial support obtainable by the organizing body of the programme in the future. Belk and Sunderman, 1947 demonstrated that laboratories participating in an quality assessment scheme could rapidly and dramatically improve their analytical performance. In some countries, participation has become mandatory, and acceptable performance is a requirement in laboratory accreditation. The need and value of the NEQAP is, therefore, evident. While there may be limitations in the national programme. efforts are being made at improving the programme within the means and resources of the organising body. The goals of the NEQAP are not just to monitor performance but also to educate. On this, matters related to and supportive of these goals have also been pursued. The annual workshop/forum on quality controls had allowed exchange of information between representatives of participating laboratories and the organising body. Recently in the 1997 MOH Quality Improvement evaluation, Quality Control has been evaluated together with the other 17 such activities. The study on knowledge, attitude and practice has provided the necessary feedback and will be used for future planning in making efforts at increasing the effectiveness and benefits of the all QC activities including this NEQAP for clinical chemistry. In addition, there is a need to look into areas such as selection of methods and test systems, and improvement of continuing education, training as well as research in quality improvement as suggested by the Quality Improvement evaluation.
In direct age-adjustment, a common age-structured population is used as standard. This population may actually exist (e.g., United States population, 1999) or may be fictitious (e.g., two populations may be combined to create a standard). In indirect age-adjustment, a common set of age-specific rates is applied to the populations whose rates are to be standardized. The simplest and most useful form of indirect adjustment is the standardized mortality ratio (SMR) (5).
A HPLC method was validated for quantification of (+)-calanolide A (1), a novel anti-HIV agent, in rat, dog and human plasma. The synthetic intermediate (+/-)-12-oxocalanolide A (2) was found to be a suitable internal standard. Compounds were extracted from plasma using a solid-phase C(18) cartridge and quantified over the assay range of 12.5 to 800 ng/ml. The method was utilized to determine (+)-calanolide A pharmacokinetics in rats, dogs and humans. This is the first report of a validated HPLC assay for determination of (+)-calanolide A concentrations in rat and dog plasma as well as human plasma obtained from clinical trials. There was no evidence of in vivo epimerization of (+)-calanolide A to its inactive epimer (+)-calanolide B (3).
A simple, sensitive and reproducible high-performance liquid chromatography (HPLC) method was developed for the determination of terazosin in human plasma. The method involves a one-step single solvent extraction procedure using dichloromethane with a 0.25 ml plasma sample. Recovery values were all greater than 90% over the concentration range 0.25-100 ng/ml. Terazosin was found to adsorb to glass or plastic tubes, but this could be circumvented by using disposable plastic tubes. Also, rinsing the injector port with methanol after each injection helped to prevent any carry-over effect. The internal standard, prazosin, did not exhibit this problem. The method has a quantification limit of 0.25 ng/ml. The within- and between-day coefficient of variation and accuracy values were all less than 7% over the concentration range 0.25-100 ng/ml and hence the method is suitable for use in pharmacokinetic studies of terazosin.
Quantitative structure-retention relationship(QSRR) method was used to model reversed-phase high-performance liquid chromatography (RP-HPLC) separation of 18 selected amino acids. Retention data for phenylthiocarbamyl (PTC) amino acids derivatives were obtained using gradient elution on ODS column with mobile phase of varying acetonitrile, acetate buffer and containing 0.5 ml/l of triethylamine (TEA). Molecular structure of each amino acid was encoded with 36 calculated molecular descriptors. The correlation between the molecular descriptors and the retention time of the compounds in the calibration set was established using the genetic neural network method. A genetic algorithm (GA) was used to select important molecular descriptors and supervised artificial neural network (ANN) was used to correlate mobile phase composition and selected descriptors with the experimentally derived retention times. Retention time values were used as the network's output and calculated molecular descriptors and mobile phase composition as the inputs. The best model with five input descriptors was chosen, and the significance of the selected descriptors for amino acid separation was examined. Results confirmed the dominant role of the organic modifier in such chromatographic systems in addition to lipophilicity (log P) and molecular size and shape (topological indices) of investigated solutes.
An investigation was conducted on the usage of a single-step extraction procedure involving the retention of a phenylboronate-salbutamol complex on an end-capped C18 solid-phase sorbent to determine the level of salbutamol in human plasma samples. Propranolol, a beta-blocker, was chosen as the internal standard for this assay. In this solid-phase clean-up method, 50 mM sodium carbonate buffer, pH 9.60, was used for conditioning the column as well as washing the endogenous interference. Under the optimal conditions, the recovery of salbutamol from spiked plasma samples was found to be high and reproducible with mean recoveries (n = 3) of more than 90% after elution by using 50% 1 M trifluoroacetic acid in methanol. This sample clean-up step was effectively analyzed under reversed-phase high-performance liquid chromatography with fluorimetric detection. The method was successfully applied to the routine measurement of salbutamol in human plasma from the bioequivalence study on the different administration route of salbutamol. Quantification of salbutamol was convincingly reported with the correlation of coefficient of 0.9980 for the concentration range from 0 to 1000 ng ml(-1). An adequate precision was achieved with both between- and within-day precisions of less than 10% (n = 6) for 100 and 1000 ng ml(-1) and less than 15% (n = 6) for 10 ng ml(-1).
A simple and sensitive high-performance liquid chromatographic (HPLC) method using ultraviolet detection was developed for the determination of testosterone in human plasma. Testosterone and the internal standard, griseofulvin, were extracted from 0.50 ml plasma sample using a mixture of dichloromethane-2,2,4-trimethylpentane (3:2, v/v). The mobile phase, consisted of 0.02 M sodium dihydrogenphosphate-acetonitrile-methanol (51:47:2, v/v) adjusted to pH 3.1 and delivered to a C(18) analytical column (150 x 4.6 mm I.D., 4 microm particles) at a flow-rate of 1 ml/min while the detection wavelength was set at 240 nm with a sensitivity range of 0.005 a.u.f.s. The method has a quantification limit of 1.6 ng/ml. Recoveries of testosterone were all greater than 92% over the linear concentration range of 1.6-400 ng/ml while that of griseofulvin was approximately 95%. The within- and between-day RSD values were all less than 8% while the accuracy values ranged from 96.0 to 106.0% over the concentration range studied. The method was applied to the analysis of early morning plasma testosterone levels of 12 healthy human male volunteers. The levels were found to range from 3.1 to 8.4 ng/ml, within the normal range reported in the literature.
A sensitive and selective high-performance liquid chromatographic method was developed for the determination of itraconazole and its active metabolite, hydroxyitraconazole, in human plasma. Prior to analysis, both compounds together with the internal standard were extracted from alkalinized plasma samples using a 3:2 (v/v) mixture of 2,2,4-trimethylpentane and dichloromethane. The mobile phase comprised 0.02 M potassium dihydrogen phosphate-acetonitrile (1:1, v/v) adjusted to pH 3.0. Analysis was run at flow-rate of 0.9 ml/min with excitation and emission wavelengths set at 260 and 365 nm, respectively. Itraconazole was found to adsorb on glass or plastic tubes, but could be circumvented by prior treating the tubes using 10% dichlorodimethylsilane in toluene. Moreover, rinsing the injector port with acetonitrile helped to overcome any carry-over effect. This problem was not encountered with hydroxyitraconazole. The method was sensitive with limit of quantification of 3 ng/ml for itraconazole and 6 ng/ml for hydroxyitraconazole. The calibration curve was linear over a concentration range of 2.8-720 ng/ml for itraconazole and 5.6-720 ng/ml for the hydroxy metabolite. Mean recovery value of the extraction procedure for both compounds was about 85%, while the within-day and between-day coefficient of variation and percent error values of the assay method were all less than 15%. Hence, the method is suitable for use in pharmacokinetic and bioavailability studies of itraconazole.
A thermoluminescent dosimetry (TLD) postal dose inter-comparison was carried out amongst radiotherapy centres in Malaysia. The aim of this TLD inter-comparison was to compare the uniformity involved in the measurement of absorbed dose among the participating centres. A set of 5 TLD chips placed within acrylic trays were mailed to all participating centres for irradiation to an absorbed dose to water of 2 Gy. Measurements were made for 6 MV and 60Co photon beams. Results show an agreement of +/- 5% for all but three radiotherapy centres. The ratios of the TLD readings to that of the reference centre are comparable with other national/regional dose inter-comparisons. The importance of a proper ongoing quality assurance program is essential in maintaining the consistency and uniformity of doses delivered.
Linear polymers have been commonly used as dental composite. However the aim of this work is to use hyperbranched polymer in an attempt to produce dental composite. The reason is because the dendritic molecules have shown low viscosity at higher molecular weight compared to the linear counterparts. Therefore, this work attempts to substitute the linear polymer with as much of hyperbranched polymer in the dental composite that would pass the required ISO 4049:1998(E) "Dentistry - Resin-based filling material". Several formulations of dental composites were used, i.e. combinations of linear-linear and linear-hyperbranched polymers for comparison. Following this, physical and mechanical characterisation were conducted based on the ISO standards such as water sorption and water solubility. Other characterisation such as polymerisation shrinkage and Vickers hardness were also evaluated. It was found that different types of resins give different physical and mechanical properties. The maximum achievable hyperbranched polymer, which passes the required ISO standard, that can be incorporated in the linear polymer to form dental composite is 43% wt.