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Biomedical subjects

J Khoo

Publications and source records attributed to J Khoo.

10 recordsLinked to original sources
PubMed2000

Low level expression of hormone-sensitive lipase in arterial macrophage-derived foam cells: potential explanation for low rates of cholesteryl ester hydrolysis.

Conversion of arterial macrophages into foam cells is a key process involved in both the initiation and progression of atherosclerotic lesions. Foam cell formation involves the progressive accumulation and storage of lipoprotein-derived cholesteryl esters. The resulting imbalance in cholesterol metabolism in arterial foam cells may be due in part to an inadequately low level of cytoplasmic neutral cholesteryl ester hydrolase (NCEH) activity. In this study, we have demonstrated that hormone-sensitive lipase (HSL) mRNA is expressed at very low levels in macrophage-derived foam cells, using the unique approach of extracting mRNA from macrophage-derived foam cells purified from human and rabbit atherosclerotic plaques coupled with reverse transcriptase polymerase chain reaction (RT-PCR). We also demonstrate that macrophage-derived foam cells isolated from rabbit atherosclerotic lesions exhibit a resistance to high density lipoprotein (HDL)-mediated cholesterol efflux along with reduced levels of NCEH activity compared to lipid-loaded mouse peritoneal macrophages. Thus, low level expression of HSL may partially account for the reduced NCEH activity observed in arterial foam cells isolated from atherosclerosis-susceptible species.

Aged↗
PubMed1997

Perceived masticatory function among elderly people.

This study investigated the status and associations of perceived chewing ability of a group of 891 elderly people, aged 55-91 years (average age 66 years). The majority of subjects (69%) considered that they could chew well. Only 9% reported poor chewing ability. This judgement was not associated with age. More men (11%) than women (6%) had reported poor chewing ability. Subjects with better perceived general and craniomandibular health reported better chewing ability. However, although related to permanent tooth loss, the perception of chewing ability was not seemingly associated with prosthetic rehabilitation. All elderly subjects with complete dental arches had no complaints of perceived chewing difficulty. Freedom from symptoms of craniomandibular pain when chewing, bilateral chewing activity and a wide choice of food range or textures were associated with favourably perceived chewing ability. This study identifies several suitable criteria for judging masticatory function and suggests that these may be used to complement chewing ability as an alternative measure of masticatory performance. These criteria are applicable to the elderly person, in particular, and warrant adequate clinical application.

Adaptation, Psychological↗
PubMed1995

Pregnancy screening by uterine artery Doppler velocimetry--which criterion performs best?

OBJECTIVE: To test whether repeating Doppler studies of the uteroplacental circulation late in gestation will improve the test's power for predicting pregnancy-induced hypertension and fetal growth restriction (FGR), and whether analysis based on a combination of quantitative and qualitative assessments of the uterine arterial waveforms will yield better results than analysis based on either alone. METHODS: A total of 358 patients considered to be at medium risk for the development of pregnancy-induced hypertension and FGR were recruited. Continuous-wave Doppler studies of the uterine arteries were performed serially at 20, 28, and 36 weeks' gestation. The values of various Doppler indices in the prediction of subsequent pregnancy complications were tested at different gestations and different cutoff levels. The overall significance of performance of the Doppler indices was assessed by the Cohen kappa index, which tests the extent of agreement between the test and the "truth" over that by random chance agreement. RESULTS: A total of 974 examination results on 334 patients were available for analysis. We found that Doppler studies of the uterine arteries at 28 and 36 weeks were less useful than studies performed at 20 weeks. Serial studies at 20 and 28 weeks showed only marginal improvement when compared with a single study at 20 weeks. The best criteria were a mean resistance index (RI) of uterine arteries above the 90th percentile and the presence of diastolic notches in both uterine arteries at 20 weeks. Although the overall kappa index only suggested fair to good agreement beyond chance, the positive predictive value for subsequent complications was good: 57% for severe complications and 93% for any complications. CONCLUSION: Doppler studies of the uterine artery as a test for the subsequent development of pregnancy complications are best performed at 20 weeks with a combination of RI measurements and the assessment of the presence of diastolic notches.

Adult↗
PubMed1995

Symptoms of craniomandibular disorder among elderly people.

This study investigated the subjective symptoms of craniomandibular disorder and the restriction in maximal mandibular opening of 891 elderly Singaporean citizens. A distribution of 22% of subjects (20% of the women and 26% of the men) reported subjective symptoms of craniomandibular disorders. The most common single symptom reported was occasional to frequent clicking sounds from the temporomandibular joints (in 15% of subjects). The other single symptoms were reported only occasionally in 2-6% of subjects. Nineteen per cent of the subjects had some restriction in maximal interincisal opening (30-39 mm) and about 1% of subjects were severely restricted in maximal opening (less than 30 mm). Subjectively evaluated limitation of wide mandibular opening was recorded for only 2% of the subjects. Background factors included general musculo-skeletal problems (54%), perceived fair to poor general health (29%), headaches (33%), work-related stress (24%), oral parafunctional clenching (4%) and grinding activity (4%). This paper confirms earlier reports that the subjective signs and symptoms of craniomandibular disorder tend to diminish in elderly people.

Age Factors↗
PubMed1991

Ossification of posterior longitudinal ligament of the cervical spine in non-Japanese Asians.

"The Japanese disease," ossification of the posterior longitudinal ligament, is not confined to the Japanese only. A similar incidence of 0.8% was found in this study among non-Japanese Asians. Of 5167 patients who attended the Mount Elizabeth Hospital in Singapore for cervical spine complaints, 43 patients were found to have ossification of the posterior longitudinal ligament, forming the largest non-Japanese series. All but one patient were of Mongolian origin, and males were affected four times more commonly than females. Diabetes mellitus was present in 16%. There was a significant association between ossification of the posterior longitudinal ligament and calcification of other cervical paraspinal ligaments. It is suggested that a generalized tendency to calcification may be an important etiological factor in ossification of the posterior longitudinal ligament. Four of the patients required surgery, and in our experience, anterior spinal fusion with removal of the ossified ligament or multilevel laminoplasty gives satisfactory results.

Adult↗
PubMed1991

A comparative study of continuous- and pulsed-wave Doppler velocimetry in fetal and uteroplacental circulation.

Continuous-wave and pulsed-wave Doppler ultrasonography are the two common methods used to study the fetal and uteroplacental circulation. We used both methods in the same patient population in three different gestations and in various fetal and uteroplacental vessels to compare the results from both machines. Thirty-one normal patients were studied at 20, 28, and 36 weeks gestation. The results showed significant correlation with no statistically significant differences between the two types of machines for the peak systolic/end-diastolic ratios and resistance index for the umbilical artery and uterine arteries. Significant differences, however, were demonstrated when the arcuate artery was studied, or when the pulsatility index was used for comparison. We therefore conclude that when different machines are used for study, comparison of the results is only valid for selected vessels and indices. Results for arcuate arteries and pulsatility index should be compared with caution.

Blood Flow Velocity↗
PubMed1985

An unusual case of sacrococcygeal teratoma and a short review.

While sacrococcygeal teratoma presents typically at birth as a mass lesion, we had a case of late presentation with the classical triad of urinary retention, constipation and weakness of legs. Interesting enough, a tuft of hair together with a small lump was noted at birth and an associated small meningocoele was found at operation. We review the literature with regard to pathogenesis, clinical features, differential diagnosis, malignant change and treatment of the tumour.

Constipation↗
PubMedDate not supplied

Hormonal requirements for growth and differentiation of ob17 preadipocyte cells in vitro.

The ob17 cell line is a clonal line established from epididymal fat pads of C57 BL/6J ob/ob mice. After conversion into adipose-like cells, ob17 presents both the morphological and biochemical properties of mature rodent fat cells. The adipose conversion process is best represented by a stochastic model in which a pool of stem cells (adipoblasts) gives rise to clusters of adipose cells and to additional stem cells that remain in the population. The role of the different factors involved in the adipose conversion process of ob17 cells is discussed, i.e. 1) mitogenic factors, that enhance the number of committed cells (ACF or adipose conversion factor(s)) 2) lipogenic factors, that enhance the expression of adipocyte enzyme markers (insulin) and 3) adipogenic factors, that are obligatory requirements for adipose conversion (triiodothyronine, growth hormone and other pituitary factors).

Adipose Tissue↗