Biochemical profiling to predict disease severity in metachromatic leukodystrophy.

Metachromatic leukodystrophy is a neurodegenerative disease that is characterized by a deficiency of arylsulfatase A, resulting in the accumulation of sulfatide and other lipids in the lysosomal network of affected cells. Accumulation of sulfatide in the nervous system leads to severe impairment of neurological function with a fatal outcome. Prognosis is often poor unless treatment is carried out before the onset of clinical symptoms. Pre-symptomatic detection of affected individuals may be possible with the introduction of newborn screening programs. The ability to accurately predict clinical phenotype and rate of disease progression in asymptomatic individuals will be essential to assist selection of the most appropriate treatment strategy. Biochemical profiling, incorporating the determination of residual enzyme protein/activity using immune-based assays, and metabolite profiling using electrospray ionization-tandem mass spectrometry, was performed on urine and cultured skin fibroblasts from a cohort of patients representing the clinical spectrum of metachromatic leukodystrophy and on unaffected controls. Residual enzyme protein/activity in fibroblasts was able to differentiate unaffected controls, arylsulfatase A pseudo-deficient individuals, pseudo-deficient compound heterozygotes and affected patients. Metachromatic leukodystrophy phenotypes were distinguished by quantification of sulfatide and other secondarily altered lipids in urine and skin fibroblasts; this enabled further differentiation of the late-infantile form of the disorder from the juvenile and adult forms. Prediction of the rate of disease progression for metachromatic leukodystrophy requires a combination of information on genotype, residual arylsulfatase A protein and activity and the measurement of sulfatide and other lipids in urine and cultured skin fibroblasts.

Parasitological and serological surveys for malaria among the inhabitants of an aborigine village and an adjacent Malay village.

Malaria surveys in an Orang Asli (aborigine) and an adjacent Malay village showed significantly higher parasite rates in the age-group 0-9 years in the former. Parasite rates declined progressively from a maximum at 0-4 years in the Orang Asli to zero at 30-39 years while in the Malays it rose progressively with age. Indirect fluorescent antibody test (IFAT) titres against schizont antigens of Plasmodium falciparum and P. cynomolgi were higher in the Orang Asli in all age-groups with a statistically significant inverse relationship between IFAT titres and parasite rates. IFAT titres in the Malay population also increased with age but were very much lower. Antibody levels detected by the enzyme-linked immunosorbent assay (ELISA) using soluble schizont antigens were also much higher in the Orang Asli and values with P. cynomolgi were higher than those with P. falciparum antigens. These differences are attributed to the higher malaria transmission in the younger age-groups of the Orang Asli and presumably greater immunological experience to a wider diversity of antigens than the Malays, thus explaining the presence of "protective" antibodies in the former but not the latter group.

Applications of biotechnology in parasitic diseases in Malaysia.

Biotechnological tools are being used in malaria, filariasis and dengue research. The main emphasis has been on the production of reagents for immunodiagnosis and research. In this respect monoclonal antibodies (McAbs) against various species and stages of the above pathogens have been produced. It is hoped that these McAbs will be useful not only in immunodiagnosis but also for seroepidemiological applications. A DNA probe against Brugia malayi has been tested in Malaysia and was found to be sensitive and specific.

Diffusion-in-gel enzyme-linked immunosorbent assay, ELISA and IFA test in the detection of malarial antibodies.

Malarial antibodies in 80 patients were measured using the diffusion-in-gel enzyme linked immunosorbent assay (DIG-ELISA), enzyme-linked immunosorbent assay (ELISA) and the indirect fluorescent antibody (IFA) test. Good correlations were obtained between all three tests in terms of sensitivity and reliability. DIG-ELISA has the advantage of being a rapid diagnostic tool for the detection of malarial antibodies.

In vitro activity of some monoclonal antibodies against Brugia malayi microfiliariae and infective larvae.

Two out of six monoclonals (McAbs) produced against subperiodic Brugia malayi infective larva (L3) antigens impaired B. malayi L3 motility independently of human buffy coat cells. Scanning electron microscopy studies showed damage to L3 surface and loss of regular cuticular annulations. The two McAbs (BML 1a and BM1 8b) did not affect B. malayi microfilaria (mf). They were IFAT-positive with B. malayi adult and L3 antigens; other McAbs which did not affect mf or L3 motility were IFAT-negative. All six McAbs did not promote cellular adherence of normal human buffy coat cells to mf or L3.

Survey of bacteria in private swimming pools.

In a survey of the bacteria in swimming pools treated with either chlorine or Baquacil in private gardens in Melbourne, the water was frequently found to be at the incorrect pH and to contain biocides at suboptimal concentrations. The general bacterial flora count was commonly greater than 200 per mL; only 14% of chlorine-treated pools and 27% of Baquacil-treated pools consistently gave counts of less than 200 per mL. Coliforms were detected in 66% of chlorine-treated pools and in 22% of Baquacil-treated pools. Escherichia coli was detected in 32% of chlorine-treated pools and 8% of Baquacil-treated pools. Staphylococcus aureus was detected in 36% of chlorine-treated pools and in 8% of Baquacil-treated pools. Pseudomonas aeruginosa was detected in 7% of chlorine-treated pools, but not at all in Baquacil-treated pools. When the biocides were maintained at the correct concentration, the indicator organisms were well controlled by both biocides. This survey indicates that owners of pools need to be made aware that their pools can harbour potentially pathogenic bacteria unless biocides are constantly maintained at the correct concentration. Baquacil generally remains above the minimum recommended concentration for approximately 14 days between routine additions, whereas chlorine can dissipate from the pool within hours of addition on hot sunny days. This probably contributed to the superior over-all performance of Baquacil in this survey.

Chromosomal abnormalities in couples with recurrent abortions.

Out of 126 couples seeking genetic advice for abortions, 95 couples have experienced 2 or more spontaneous abortions. Of these, chromosome banding studies were carried out in one or both partners (92 women and 85 men). Abnormal karyotypes were found in 2 males. Both abnormalities were balanced translocations: 46 XY t(5q+ 11q-) and 45 XY t(13/14). This represents an overall frequency of 1.1% which is comparable to the reported incidence in the literature.

Modulation of MHC expression on human endothelial cells by sera from patients with systemic lupus erythematosus.

Major histocompatibility complex (MHC) antigen expression on cells is a prerequisite for immune interaction with activated T-cells. This study examined the ability of sera from patients with systemic lupus erythematosus (SLE) to modulate MHC expression on vascular endothelial cells. SLE sera were able to selectively upregulate MHC class I antigen expression on cultured human umbilical venous endothelial (HUVE) cells, without concomitant induction of MHC class II antigen. The stimulation index (SI) for MHC class I expression produced by SLE sera (1.21 +/- 0.23) was significantly higher than those for normal controls (1.01 +/- 0.10) (P < 0.0001) and non-SLE patients (1.12 +/- 0.14) (P < 0.05). Additionally, active SLE patients had higher mean SI than inactive patients (P < 0.001). Preincubation of SLE sera with Protein A-Sepharose beads conjugated with antibodies against tumor necrosis factor-alpha and interferon-alpha was able to significantly reduce their ability to upregulate class I MHC expression by HUVE cells, indicating that these cytokines were responsible for the modulatory effect. This could be an important mechanism for the immune-mediated vascular injury seen in SLE.