MyMedR

Fulltext Detection of circulating plasmodial antigens in human sera by sandwich ELISA with monoclonal antibodies

Lim PK, Mak JW, Yong HS

Southeast Asian J. Trop. Med. Public Health, 1992 Dec;23(4):735-9.

Two monoclonal antibodies (MAbs), one produced against Plasmodium falciparum (PF-IG8) and the other against P. cynomolgi (PC-IE12) schizont antigens were used in a sandwich ELISA for the detection of circulating plasmodial antigens in sera of patients infected with either P. falciparum, P. vivax or P. malariae. The mean +/- SD optical density (OD) values for the normal control group using PF-108 and PC-1E12 were 0.351 +/- 0.036 and 0.205 +/- 0.044, respectively. Mean OD values for the three infected groups were found to be significantly higher than those of the normal control group for both MAbs. However, ELISA values for individual serum specimens did not correlate with the level of parasitemia in the infected blood. Using a cut-off point of mean OD +/- 3 SD of the normal control group as indicating a positive reading, the specificity of this assay with both MAbs was 100%. The sensitivity of the assay using PF-1G8 was 95% while that obtained with PC-1E12 was 98%.

Strain differences in Blastocystis isolates as detected by a single set of polymerase chain reaction primers

Init I, Mak JW, Lokman Hakim S, Yong HS

Parasitol Res, 1999 Feb;85(2):131-4.

PMID: 9934962

A total of 20 isolates of Blastocystis were characterized using a single set of polymerase chain reaction (PCR) primers. The amplification product revealed five types of pattern. All four isolates from Singapore yielded PCR products quite different from those of the local isolates. However, most of the local isolates showed a major product at either 280 or 500 bp, or both. We also suspected that the amplification product detected at 280 bp might be an indicator of the pathogenicity of this parasite. One isolate (M12) obtained from a monkey showed patterns similar to those of human isolates (10203 and KP1) and probably belongs to the same strain. The results indicate that the intraspecific or interstrain variations in these 20 Blastocystis isolates belong to 5 different patterns. The differences among isolates of the same strain revealed by the presence or absence of certain amplification products showed further intrastrain variations in this parasite.

A study of the sensitivity of Plasmodium falciparum to chloroquine and mefloquine using the in vitro microtechnique in Peninsular Malaysia

Ho KB, Mak JW, Ramadas M

Trans R Soc Trop Med Hyg, 1987;81(2):257-9.

PMID: 3303483

Plasmodium falciparum drug sensitivities to chloroquine and mefloquine were assessed with WHO in vitro microtechnique test kits in 5 localities near the border with Thailand in Peninsular Malaysia. 105 of 113 (92.9%) parasite isolates were successfully tested and 103 (98.1%) showed resistance to chloroquine with parasite growth even at greater than or equal to 5.7 pmol of the drug. All these isolates were sensitive to mefloquine, parasite growth being inhibited at less than or equal to 11.3 pmol of the drug.

Armigeres subalbatus incriminated as an important vector of the dog heartworm Dirofilaria immitis and the bird Cardiofilaria in urban Kuala Lumpur

Cheong WH, Mak JW, Naidu S, Mahadevan S

Southeast Asian J. Trop. Med. Public Health, 1981 Dec;12(4):611-2.

PMID: 6124044

Long term maintenance of Toxoplasma gondii (Rh strain) in Vero cell line and use of harvested antigens for immunodiagnosis

Suresh K, Mak JW, Yong HS

Southeast Asian J. Trop. Med. Public Health, 1991 Dec;22 Suppl:124-8.

PMID: 1822869

Thirty in vitro serial passages of Toxoplasman gondii cultures in Vero cell line performed once in every five days had a mean increase in parasite count of 74.4 +/- 14.8 times from that of initial counts. Long term cultures in Vero cell line did not alter the virulence of the parasite. The good correlation (r = 0.99) between the IFA titer and ELISA OD values using the parasite antigens from in vitro sources indicates that long term maintenance of T. gondii in culture does not affect significantly the ability to recognize antibodies to surface and soluble antigens. The results also show that soluble antigens containing host cells can be directly used for immunodiagnostic purposes without purification. The in vitro maintenance of T. gondii is safer and cheaper when compared to the in vivo method.

Immunoglobulin levels in various clinical groups of human Brugian filariasis in Malaysia

Sim BK, Mak JW, Kwa BH

Z Parasitenkd, 1983;69(3):371-5.

PMID: 6880344

Quantitation of serum immunoglobulin M, G, A, D and E levels was carried out in Malaysians with Brugia malayi infections. Results showed highly elevated levels of IgM and IgE as well as moderately elevated levels of IgG. These were most significant in patients with tropical pulmonary eosinophilia or elephantiasis. Serum IgE levels were extremely high in microfilaraemic patients (6,060 +/- 3,958 IU ml) probably due to a constant antigenic stimulation by dead and dying microfilariae.

Fulltext Immune response in acute Toxoplasma infection of Balb/C, ICR and CBA/J mice

Suresh K, Mak JW, Yong HS

Southeast Asian J. Trop. Med. Public Health, 1991 Sep;22(3):452-4.

PMID: 1818401

Fulltext In vitro culture of Toxoplasma gondii

Suresh K, Mak JW, Yong HS

Southeast Asian J. Trop. Med. Public Health, 1991 Sep;22(3):449-51.

PMID: 1818400

Experimental chemotherapy of lymphatic filariasis. A review

Mak JW, Navaratnam V, Ramachandran CP

Ann Trop Med Parasitol, 1991 Feb;85(1):131-7.

PMID: 1888210

An intense global collaborative effort under the leadership of the Steering Committee of the Filariasis Scientific Working Group of the Tropical Diseases Research Programme, World Health Organization, has brought together researchers, pharmaceutical chemists and clinicians in the development and search for antifilarial compounds which are more effective and more convenient to administer than diethylcarbamazine citrate, the current drug of choice for lymphatic filariasis. The Brugia spp.-rodent model has been used extensively for the primary screening and B. pahangi infections in the dog or cat for the secondary screening, of potential filaricides. Recently, the leaf-monkey (Presbytis spp.) infected with subperiodic B. malayi or Wuchereria kalimantani has been used for the tertiary evaluation and pharmacokinetic studies of compounds which have shown effectiveness in the primary and secondary screens. Both P. cristata and P. melalophos are extremely susceptible to subperiodic B. malayi infection, but the former is a better host as a higher peak microfilaremia and adult worm recovery rate were obtained. Although more than 30 potential filaricides have been evaluated in the tertiary screen, only a few compounds have shown some promise against lymphatic filariasis. CGP 20376, a 5-methoxyl-6-dithiocarbamic-S-(2-carboxy-ethyl) ester derivative of benzothiazole, had complete adulticidal and microfilaricidal activities against the parasite at a single oral dose of 20 mg kg-1. However, as the compound or its metabolites caused hepatotoxicity, its clinical use in the present formulation is not recommended.(ABSTRACT TRUNCATED AT 250 WORDS)

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

Tan MA, Mak JW, Yong HS

Trop. Med. Parasitol., 1989 Sep;40(3):317-21.

PMID: 2617040

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.

Fulltext Cutaneous larva migrans--report of three probable cases

Hanjeet K, Ow Yang CK, Mak JW

Med J Malaysia, 1988 Sep;43(3):263-6.

PMID: 3241589

[Description of Onchocerca dewittei n. sp. (Filarioidea), parasite of Sus scrofa, in Malaysia (author's transl)]

Bain O, Ramachandran CP, Petter F, Mak JW

Ann Parasitol Hum Comp, 1977 7 1;52(4):471-9.

PMID: 931324

Onchocerca dewittei n. sp. was collected from a wild Boar at the metatarse level (tendons and subcutaneous connective tissue); it can be differentiated from other species by the female cuticle showing straight ridges which overlap in the lateral fields, and by its relatively thick microfilaria (length 228-247 mu and width 6-7 mu). This suidean Onchocerca displays some primitive characters such as straight ridges and persistency of ten pairs of caudal papillae in the male; but as a whole this species is undoubtedly more highly evolved than O. raillieti Bain, Müller and coll., 1976, a parasite of Equidae.

Experimental infection of Rattus sabanus and Rattus muelleri with subperiodic Brugia malayi

Sivanandam S, Mak JW, Lai PF

Southeast Asian J. Trop. Med. Public Health, 1975 Mar;6(1):68-73.

PMID: 1145240

R. sabanus and R. muelleri are very common in the lowland forests of Malaysia. In nature they are infected with Breinlia sp. and D. ramachandrani. In an attempt to determine whether they are also susceptible to subperiodic B. malayi and thereby being potential reservoirs of infection of the disease, 24 R. muelleri and 17 R. sabanus were experimentally infected with the parasite. Results show that although they can support the full development of the parasite, they are poor hosts. This confirms the observation that in Malaysia natural infection of Rattus spp. with the parasite has not been seen. These rats therefore are probably not important in the zoonotic transmission of subperiodic B. malayi in Malaysia.

Susceptibility studies of Plasmodium falciparum isolates and clones against cycloguanil and pyrimethamine using the modified in vitro microtechnique

Ang HH, Chan KL, Mak JW

J Parasitol, 1996 Dec;82(6):1029-31.

PMID: 8973418

Six clones were derived from each Malaysian Plasmodium falciparum isolate and characterized for their susceptibilities against type II antifolate drugs, cycloguanil and pyrimethamine. Results showed that these isolates were of a heterogeneous population, with average IC50 values of Gombak C clones at 0.012-0.084 microM and 0.027-0.066 microM, ST 9 clones at 0.019-0.258 microM and 0.027-0.241 microM, ST 12 clones at 0.015-0.342 microM and 0.012-0.107 microM, ST 85 clones at 0.022-0.087 microM and 0.024-0.426 microM, and ST 148 clones at 0.027-0312 microM and 0.029-0.690 microM against cycloguanil and pyrimethamine, respectively. Generally, most of these clones displayed susceptibility patterns similar to their parent isolates except ST 9/A4, ST 9/A7, ST 9/B5, ST 9/D9, ST 9/D10, ST 148/A4, ST 148/A5, ST 148/A7, ST 148/F7, ST 148/F8 clones, which were sensitive at 0.027 microM, 0.019 microM, 0.022 microM, 0.063 microM, 0.037 microM, 0.031 microM, 0.042, microM, 0.042 microM, 0.062 microM, and 0.027 microM, whereas, ST 12/D7 clone was resistant at 0.342 microM, against cycloguanil respectively. However, ST 9/A4, ST 9/D8, ST 12/D5, ST 85/A5, ST 85/B3, ST 85/B4, ST 85/D3, ST 85/D7, ST 148/A6, and ST 148/A7 clones were resistant to pyrimethamine at 0.158 microM, 0.241 microM, 0.107 microM, 0.223 microM, 0.393 microM, 0.402 microM, 0.426 microM, 0.115 microM, 0.690 microM, and 0.520 microM, respectively.

Effect of 7-day daily replacement of culture medium containing Eurycoma longifolia Jack constituents on the Malaysian Plasmodium falciparum isolates

Ang HH, Chan KL, Mak JW

J Ethnopharmacol, 1995 Dec 15;49(3):171-5.

PMID: 8824743 DOI: 0.1016/0378-8741(95)01321-0

Six Malaysian chloroquine-resistant Plasmodium falciparum isolates were cultured in vitro following the candle-jar method. Antimalarial evaluations of daily replacement of culture medium containing chloroquine and a semi-purified extract of Eurycoma longifolia Jack (containing 13 beta, 18-dihydroeurycomanol (1), eurycomanol-2-O-beta-D-glucopyranoside (2), eurycomanol (3) and eurycomanone (4)) were performed on 6-well plates at 37 degrees C for a week. Presence or absence of the parasites was determined microscopically on thin-film Giemsa-stained preparations. Results showed that the antimalarial activity of Eurycoma longifolia Jack was dose-dependent and reached a maximum of < 50% at 0.07-5.00 micrograms ml-1 after 1 day post-treatment. However, complete inhibitions were observed at 1.25-5.00 micrograms ml-1 extract after 3 days post-treatment and 0.62 and 0.31 micrograms ml-1 after 4 and 6 days post-treatment, respectively. Further results indicated that chloroquine exhibited total inhibition at concentrations > 2.50 and 0.62 micrograms ml-1 after 1 and 2 days post-treatment, respectively and at all concentrations after 3 days post-treatment.

Fulltext Immediately modifiable risk factors attributable to colorectal cancer in Malaysia

Naing C, Lai PK, Mak JW

BMC Public Health, 2017 08 04;17(1):637.

PMID: 28778191 DOI: 10.1186/s12889-017-4650-8

BACKGROUND: This study aimed to estimate potential reductions in case incidence of colorectal cancer attributable to the modifiable risk factors such as alcohol consumption, overweight and physical inactivity amongst the Malaysian population.

METHODS: Gender specific population-attributable fractions (PAFs) for colorectal cancer in Malaysia were estimated for the three selected risk factors (physical inactivity, overweight, and alcohol consumptions). Exposure prevalence were sourced from a large-scale national representative survey. Risk estimates of the relationship between the exposure of interest and colorectal cancer were obtained from published meta-analyses. The overall PAF was then estimated, using the 2013 national cancer incidence data from the Malaysian Cancer Registry.

RESULTS: Overall, the mean incidence rate for colorectal cancer in Malaysia from 2008 to 2013 was 21.3 per 100,000 population, with the mean age of 61.6 years (±12.7) and the majority were men (56.6%). Amongst 369 colorectal cancer cases in 2013, 40 cases (20 men, 20 women), 10 cases (9 men, 1 woman) or 20 cases (16 men,4 women) would be prevented, if they had done physical exercises, could reduce their body weight to normal level or avoided alcohol consumption, assuming that these factors are causally related to colorectal cancer. It was estimated that 66 (17.8%;66/369) colorectal cancer cases (42 men, 24 women) who had all these three risk factors for the last 10 years would have been prevented, if they could control these three risk factors through effective preventive measures.

CONCLUSIONS: Findings suggest that approximately 18% of colorectal cancer cases in Malaysia would be prevented through appropriate preventive measures such as doing regular physical exercises, reducing their body weight to normal level and avoiding alcohol consumption, if these factors are causally related to colorectal cancer. Scaling-up nationwide public health campaigns tailored to increase physical activity, controlling body weight within normal limits and avoid alcohol intake are recommended. Future studies with other site-specific cancers and additional risk factors are needed.

Fulltext Comparison of the quantitative buffy coat technique with the conventional thick blood film technique for malaria case detection in the field

Mak JW, Normaznah Y, Chiang GL

Singapore Med J, 1992 Oct;33(5):452-4.

PMID: 1455266

The quantitative buffy coat (QBC) technique was compared with the conventional thick blood film technique in a malaria survey carried out in a mesoendemic area of malaria in Betau, Pahang, Malaysia. The QBC technique was found to be a rapid technique but had a sensitivity of about 56% and a specificity of 95%, using the thick blood film method as the "gold standard". Malaria species identification was unsatisfactory with the QBC technique as it could identify parasites correctly in only about 60% of specimens. It was unable to detect as positive about 58% of specimens which had parasite counts < or = 500 per ul but could detect about 94% of those with counts > 500 per ul. This difference in positive detection rate was significantly different (p < 0.05). It cannot quantify parasitemia easily and the specimens cannot be stored for future reference and for quality control purposes. It is therefore concluded that the QBC technique cannot replace the classical thick blood film technique for use in malaria control programmes. Its use may be appropriate in situations like busy blood banks and outpatient clinics where rapid screening of malaria infection is needed but where experienced malaria microscopists may not be available.

Efficacy of ivermectin against Parastrongylus malaysiensis infection in rats

Ambu S, Mak JW, Ng CS

J Helminthol, 1992 Dec;66(4):293-6.

PMID: 1293196

The efficacy of ivermectin on experimental infections of P. malaysiensis in rats was determined. Ivermectin was 99.4% and 97.9% effective at a dosage of 400 meg and 800 meg respectively at seven days post-infection. The same two dosages of ivermectin when given at 14 days post infection had an efficacy of 100%. However, as an adulticide it had only 40.7% efficacy. Ivermectin may therefore be useful for the treatment of parastrongyliasis due to the larval stages of the worm which can cause significant pathology in man and animals.

Identification of some common infective filarial larvae in Malaysia

Yen PK, Zaman V, Mak JW

J Helminthol, 1982 Mar;56(1):69-80.

PMID: 7069185

Infective larvae of Wuchereria, Brugia, Breinlia, Dirofilaria and Setaria species from an experimental vector, Aedes togoi, are compared. The distinctive bubble-like caudal papillae of Wuchereria bancrofti are readily distinguishable from the protuberant ones of Brugia spp; the 'ear-like' papillae of Breinlia are distinct from the 'knob-like' ones of Dirofilaria or the 'thorn-like' terminal papilla of Setaria.

Fulltext Is Plasmodium vivax malaria a severe malaria?: a systematic review and meta-analysis

Naing C, Whittaker MA, Nyunt Wai V, Mak JW

PLoS Negl Trop Dis, 2014 Aug;8(8):e3071.

PMID: 25121491 DOI: 10.1371/journal.pntd.0003071

BACKGROUND: Plasmodium vivax is one of the major species of malaria infecting humans. Although emphasis on P. falciparum is appropriate, the burden of vivax malaria should be given due attention. This study aimed to synthesize the evidence on severe malaria in P. vivax infection compared with that in P. falciparum infection.
METHODS/PRINCIPAL FINDINGS: We searched relevant studies in electronic databases. The main outcomes required for inclusion in the review were mortality, severe malaria (SM) and severe anaemia (SA). The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Overall, 26 studies were included. The main meta-analysis was restricted to the high quality studies. Eight studies (n = 27490) compared the incidence of SM between P. vivax infection and P. falciparum mono-infection; a comparable incidence was found in infants (OR: 0.45, 95% CI:0.04-5.68, I2:98%), under 5 year age group (OR: 2.06, 95% CI: 0.83-5.1, I2:83%), the 5-15 year-age group (OR: 0.6, 95% CI: 0.31-1.16, I2:81%) and adults (OR: 0.83, 95% CI: 0.67-1.03, I2:25%). Six studies reported the incidences of SA in P. vivax infection and P. falciparum mono-infection; a comparable incidence of SA was found among infants (OR: 3.47, 95%:0.64-18.94, I2: 92%), the 5-15 year-age group (OR:0.71, 95% CI: 0.06-8.57, I2:82%). This was significantly lower in adults (OR:0.75, 95% CI: 0.62-0.92, I2:0%). Five studies (n = 71079) compared the mortality rate between vivax malaria and falciparum malaria. A lower rate of mortality was found in infants with vivax malaria (OR:0.61, 95% CI:0.5-0.76, I2:0%), while this was comparable in the 5-15 year- age group (OR: 0.43, 95% CI:0.06-2.91, I2:84%) and the children of unspecified-age group (OR: 0.77, 95% CI:0.59-1.01, I2:0%).
CONCLUSION: Overall, the present analysis identified that the incidence of SM in patients infected with P. vivax was considerable, indicating that P. vivax is a major cause of SM. Awareness of the clinical manifestations of vivax malaria should prompt early detection. Subsequent treatment and monitoring of complications can be life-saving.

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