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Biomedical subjects

K W Lai

Publications and source records attributed to K W Lai.

14 recordsLinked to original sources
PubMed2003

Changes in heart rate and R-wave amplitude with posture.

BACKGROUND: Effect of gravity on heart rate and blood pressure are well documented but the effect of posture on R-wave amplitude has not been studied. AIM: To investigate the effect of posture on the heart rate (HR) and R-wave amplitude (RWA). METHODS: The electrocardiograph (ECG) was recorded in 20 young subjects on two occasions. A 5 minute recording of resting ECG was taken with the subject adopting the following postural cycle: lying, sitting, standing, sitting and lying positions. RESULTS: The standing HR was significantly higher than that in sitting and lying positions, but the RWA was significantly lower in standing compared to the sitting and lying postures. The HR significantly increased at the initial phase of postural changes, irrespective of the position. For example, the HR increased from lying to sitting (66.6+/-2.3 to 85.0+/-10.9 beat x min(-1)) but also increased when changed from sitting to lying (70.6+/-10.6 to 85.2+/-8.7 beat x min(-1)). CONCLUSION: Body posture has an effect on HR and RWA. The changes are probably related to orthostatic haemodynamic stress as well as changes in cardiac electrical axis. Whether the cause of the initial increase in the HR during postural change was attributed to skeletal muscle reflex or venous return requires further investigation.

Adult↗
PubMed2003

Inhibitor of apoptosis proteins and ovarian dysfunction in galactosemic rats.

Galactosemia is a genetic disease with deficiency of galactose-1-uridyltransferase, resulting in the accumulation of galactose or galactose-1-phosphate in the blood and tissues. Rats were fed with normal rat chow and with a high-galactose diet for 4 weeks to give control and galactosemic groups, and their ovarian function was studied. The two groups of rats were injected with pregnant mare's serum gonadotrophin (PMSG) and were killed at different time points after human chorionic gonadotrophin (hCG) injection. The number of oocytes ovulated in the controls was significantly higher than in the galactosemic group. Morphometric studies of the ovaries also showed a higher number of corpora lutea in the controls. Western blot analysis of granulosa cells showed that the overall expressions of Fas and FasL were lower in the control group and their expressions of inhibitor of apoptosis proteins (IAPs) were higher than in the galactosemic group, especially at 8 h post hCG injection. TDT-mediated dUTP-biotin nick end-labeling (TUNEL) and immunohistochemical staining of ovarian sections with Ki-67 and IAPs showed more apoptotic granulosa cells in the galactosemic group and the expressions of IAPs in granulosa cells also confirmed the result of the Western blot. These findings support our hypothesis that ovarian dysfunction in galactosemic rats is due to increased apoptosis in granulosa cells of maturing follicles.

Animals↗
PubMed2003

Knowledge of cardiopulmonary resuscitation among the public in Hong Kong: telephone questionnaire survey.

OBJECTIVES: To evaluate the knowledge of basic life-support and training experience in cardiopulmonary resuscitation among the public in Hong Kong and to identify areas for improvement in public education. DESIGN: Telephone interview using a structured multiple-choice questionnaire. SETTING: Random cross-section of the Hong Kong public, from mid-March to May 2002. PARTICIPANTS: Men and women aged 16 years and older selected using random telephone dialling. MAIN OUTCOME MEASURE: Overall score in the cardiopulmonary resuscitation knowledge questionnaire. RESULTS: Of the 357 participants, approximately 12% had received cardiopulmonary resuscitation training. Cardiopulmonary resuscitation knowledge in Hong Kong was poor, even among the previously trained and especially with regard to circulatory maintenance. The most common reason for not taking cardiopulmonary resuscitation training was lack of time. CONCLUSION: The degree of citizen preparedness in initiating cardiopulmonary resuscitation is very poor in Hong Kong. Intensified educational efforts and exploration of new approaches to improve this first stage in the chain of survival are warranted.

Adolescent↗
PubMed2001

Plasma nitric oxide level in heart failure secondary to left ventricular diastolic dysfunction.

Nitric oxide (NO) is a free radical that is elevated in the plasma of patients with systolic heart failure. However, its relation to diastolic function is unknown. This study investigated the relation between the level of stable end-products of plasma NO (NOx level) and diastolic function in patients with heart failure. We performed echocardiographic Doppler studies in 76 patients (mean age of 66 +/- 10 years, 75% men) with congestive heart failure. Left ventricular (LV) diastolic dysfunction was classified as either a restrictive (RFP) or nonrestrictive filling pattern (non-RFP). Same day venous total nitrite plus nitrate levels were measured by chemiluminscence. Both patients with isolated diastolic heart failure (ejection fraction >50%) (77 +/- 9 micromol/L, n = 33) and systolic failure (ejection fraction < or = 50%) (115 +/- 17 micromol/L, n = 43) had significantly higher plasma NOx levels than controls (37 +/- 2 micromol/L, both p <0.001). RFP coexists mostly in patients with systolic heart failure (15 of 18), and these patients had a higher NOx level than patients with systolic failure and a non-RFP (n = 28) (163 +/- 35 vs 88 +/- 16 micromol/L, p <0.05). Patients who were not on oral nitrate drugs had insignificant lower plasma NOx levels than those on regular nitrate therapy, although it was still higher than controls. Plasma NOx level did not correlate with LV ejection fraction. Stepwise multiple regression analysis confirmed that the presence of RFP was the only independent predictor of NOx, and hence NO production. Plasma NOx level is elevated in patients with isolated diastolic heart failure. In addition, in patients with LV systolic failure, the severity of LV diastolic dysfunction determines the amount of NO production.

Aged↗
PubMed1999

Methylation of p16INK4A in primary gynecologic malignancy.

The p16INK4A gene mapped on band p21 of chromosome 9 can be inactivated via multiple mechanisms including homozygous deletion, point mutation and promoter hypermethylation in various human tumors. A polymerase chain reaction (PCR) based analysis was performed to examine methylation of the p16INK4A gene promoter in 196 primary gynecologic malignancies including 98 cervical, 49 endometrial and 49 ovarian carcinomas. Methylation of p16INK4A was detected in 31% of cervical, 20% of endometrial, and 4% of ovarian carcinomas, respectively. The incidence of p16INK4A methylation in patients with cervical and endometrial carcinomas at advanced stages (stages III-IV) was statistically higher than those at early stages (stages I-II). There were also significant differences in the incidence of p16INK4A methylation in both cancers between the patients who had died of their disease or were alive with evidence of disease, and those without evidence of disease. The results indicate that methylation of the p16INK4A gene is present in a proportion of primary gynecologic malignancies and this alteration may be associated with poor outcome in cervical and endometrial carcinomas.

Adult↗
PubMed1999

A comparative study of a digital radiography system.

The present study aimed to examine the efficiency of a new digital radiography system that was installed in the Royal Adelaide Hospital in September 1997, as compared to the existing conventional radiography system. A total of 55 examinations were observed over a 3-week period in January, and these consisted of 18 digital and 10 conventional chest examinations, and 27 conventional orthopaedic examinations. These were combined with 18 digital orthopaedic examinations recorded from a prior study. Total examination time was broken into several components, of which reporting time was of the most interest. The mean reporting times for digital and conventional chest examinations were 17 and 25 min, respectively, a significant (P < 0.1) 8-min difference. The orthopaedic examinations revealed mean reporting times of 8 and 26 min for digital and conventional systems, respectively; a significant (P < 0.001) 18-min difference. These results demonstrate that the digital system is a faster, more efficient system for the reporting of X-rays.

Data Collection↗
PubMed1997

p16INK4 and p15INK4B alterations in primary gynecologic malignancy.

Chromosome 9 abnormalities have been found in primary tumors and cell lines from human gynecologic malignancy. Alterations of p16INK4 and p15INK4B genes mapped on the band p21 of chromosome 9 have been detected in various human tumors, but the role of these genes as tumor suppressors in vivo appear to be dependent on tumor type. Polymerase chain reaction (PCR)-based analysis was performed to search for lesions of these genes in 202 primary gynecologic malignancies. Homozygous deletions of p16INK4 were detected in 7 of 128 (5%) cervical, 1 of 41 (2%) endometrial, 2 of 27 (7%) ovarian, and 3 of 6 (50%) vulvar carcinomas, while homozygous deletions of p15INK4B were detected in 19 of 128 (15%) cervical, 1 of 41 (2%) endometrial, 9 of 27 (33%) ovarian, and 3 of 6 (50%) vulvar carcinomas, respectively. No mutations were found in exon 2 of p16INK4 from 161 cases of gynecologic malignancy without deletion of p16INK4. All 3 cases of vulvar carcinoma showing homozygous deletions of p16INK4 and p15INK4B were at advanced clinical stage (stage III-IV), while all 7 cases of cervical carcinoma and 2 cases of ovarian carcinoma showing homozygous deletion of p16INK4 were at early stage (stage I-II). The results indicate that homozygous deletions of p16INK4 and/or p15INK4B genes may play a role in a subset of primary gynecologic malignancy.

Carrier Proteins↗
PubMed1995

Sister-chromatid exchanges in lymphocytes from methimazole-induced hypothyroid mice.

The inhibitory effect of an antithyroid drug on mouse T lymphocytes was investigated. Inbred C57BL/6 mice were provided with an antithyroid drug, methimazole, for 2, 4 and 6 weeks and the in vitro responses of the lymphocytes were studied. The proliferative responses of T lymphocytes from the spleen of methimazole (MMI)-treated mice significantly (p < 0.05) decreased following concanavalin A stimulation, and the inhibitory effect became prominent with the increased duration of MMI treatment. A concomitant increase in the frequency of induced sister-chromatid exchanges was also observed in these T lymphocytes. When the splenocytes were stimulated with concanavalin A for 24 h, their ability to produce interleukin-2 (IL-2) was significantly decreased (p < 0.05). The results indicated that methimazole interfered with the normal proliferation of T lymphocytes by suppressing the production of IL-2, a cytokine also known as T cell growth factor, as well as inducing a higher incidence of sister-chromatid exchange during cell division.

Animals↗