Aortic and coronary atherosclerosis in the Malaysian Orang Asli

Metabolomics and partial least square discriminant analysis to predict history of myocardial infarction of self-claimed healthy subjects: validity and feasibility for clinical practice

Background

The dynamics of metabolomics in establishing a prediction model using partial least square discriminant analysis have enabled better disease diagnosis; with emphasis on early detection of diseases. We attempted to translate the metabolomics model to predict the health status of the Orang Asli community whom we have little information. The metabolite expressions of the healthy vs. diseased patients (cardiovascular) were compared. A metabotype model was developed and validated using partial least square discriminant analysis (PLSDA). Cardiovascular risks of the Orang Asli were predicted and confirmed by biochemistry profiles conducted concurrently.

Results

Fourteen (14) metabolites were determined as potential biomarkers for cardiovascular risks with receiver operating characteristic of more than 0.7. They include 15S-HETE (AUC = 0.997) and phosphorylcholine (AUC = 0.995). Seven Orang Asli were clustered with the patients’ group and may have ongoing cardiovascular risks and problems. This is supported by biochemistry tests results that showed abnormalities in cholesterol, triglyceride, HDL and LDL levels.

Conclusions

The disease prediction model based on metabolites is a useful diagnostic alternative as compared to the current single biomarker assays. The former is believed to be more cost effective since a single sample run is able to provide a more comprehensive disease profile, whilst the latter require different types of sampling tubes and blood volumes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13336-015-0018-4) contains supplementary material, which is available to authorized users.

Plasma lipids and apolipoproteins in a population of Orang Asli ('aborigines') from West Malaysia

Plasma total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDLC) and apolipoproteins Al (apo Al) and B (apo B) were measured in a sample of subjects from the Semai tribe of Orang Asli in peninsular Malaysia. They appeared to exhibit the lowest TC ever recorded (1.6 for males and 1.9 mmol/l for females) and relatively high TG (1.4 mmol/l for males and 1.5 mmol/l for females)(means for the whole sample). There was little apparent aging gradient in any of the plasma analytes. but the group of men aged 21-40 had lower HDLC than the corresponding female group. Both low density lipoprotein cholesterol (LDLC) (calculated) and HDLC as well as their corresponding apolipoproteins were correspondingly very low. There was a significant correlation between apo AI and HDLC in both sexes.

Amyloidosis in Malaysian aborigines (Orang Asli)

Material from 334 consecutive autopsies on Orang Asli subjects performed in the University Hospital, Kuala Lumpur between May 1967 and June 1978 was examined for amyloidosis. Nine positive cases were found, all in patients above 40 years of age, giving an age-corrected incidence of about 9%. In 6 cases, amyloidosis was probably secondary to tuberculosis. The remaining 3 cases exhibited a pericollagenous distribution characteristic of primary amyloidosis. Involvement of the heart and lungs was prominent. However, there were considerable similarities in the distribution and staining properties of the amyloid in the 2 groups. Though both the heart and kidney were frequently affected, the kidney was the most common organ to give rise to clinical symptoms. Infection probably plays a major contributory role in amyloidosis in the Orang Asli.

Hepatocellular carcinoma in the Malaysian Orang Asli

Necropsies were performed on 285 consecutively unclaimed Orang Asli bodies from Gombak Orang Asli Hospital during an eight-year period from May 1967 to April 1975. Of the 25 malignant neoplasms, hepatocellular carcinoma was by far the commonest (36%). The nine patients with this neoplasm had coexistant macronodular cirrhosis. There were 20 cases of cirrhosis; 45% of these had coexistant hepatocellular carcinoma. The 53,000 Orang Aslis living in West Malaysia comprise three tribes, the Negrito, Senoi, and Melayu Asli (Proto Malays). The Sinoi appear to have a high predilection for liver cancer, all our nine cases occurring in this group. These aboriginal people live in the jungles where they practice shifting cultivation and maintain their own dietary and social customs. Detailed studies of their dietary habits may provide a clue to the etiology of liver cancer in these people.

Diet-induced aortic atherosclerosis in Malaysian long-tailed monkeys (Macaca irus)

Moderate hypercholesterolaemia has been produced in eight adult male M. irus monkeys by feeding an egg-toast preparation containing butter and 0.14 per cent. total cholesterol. At autopsy, after two to four years of persistent hypercholesterolaemia, there was massive fatty streaking of the aorta involving 21 to 78 per cent. of the intimal surface. The distribution and morphology of the fatty streaks was similar to that in man. In addition, there were fibrous plaques including "soft" lipid-rich atherosclerotic plaques identical to their human counterpart. There was no grossly detectable thromobosis, haemorrhage or ulceration. Atherosclerotic lesions were also present in the coronary, carotid, subclavian, iliac and femoral arteries. In a control group of monkeys fed a low-fat, cholesterol-free diet, arterial lesions were identical in type and extent to those in freshly captured wild monkeys.