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Biomedical subjects

C Ng

Publications and source records attributed to C Ng.

At least 55 records · Page 3Linked to original sources
PubMed1996

Autoregulation of myocardial glycogen concentration during intermittent hypoxia.

During hypoxia, the heart consumes glycogen to generate ATP. Tolerance of repetitive hypoxia logically requires prompt replenishment of glycogen, a process whose regulation is not fully understood. To examine this, we imposed a defined hypoxic stimulus on the rat heart while varying its workload. In intact rats, hypoxia reduced myocardial glycogen approximately 30% and increased both the fraction of glycogen synthase in its physiologically active (GS I) form (from 0.24 +/- 0.06 to 0.82 +/- 0.07; P < 0.005) and glycogen synthesis (from 0.087 +/- 0.011 to 0.375 +/- 0.046 mumol.g-1.min-1; P < 0.005). Reducing cardiac work (with propranolol or heterotopic transplantation) reduced glycogen breakdown, glycogen synthase activation, and glycogen synthesis in parallel, stepwise fashion in intact rats. Correspondingly, hypoxia increased GS I activity in the perfused heart in vitro, but only under conditions where glycogen was consumed. This suggests myocardial glycogen synthase is activated by systemic hypoxia and catalyzes rapid posthypoxic glycogen synthesis. Hypoxic glycogen synthase activation appears to be a proportionate, wholly intrinsic response to local glycogenolysis, operating to preserve myocardial glycogen stores independent of any extracardiac mediator of carbohydrate metabolism.

Animals↗
PubMed1995

Effects of 5 alpha-dihydrotestosterone (DHT) on the transcription of nm23 and c-myc genes in human prostatic LNCaP cells.

Proliferation of the androgen-dependent human prostate LNCaP cells was increased by the androgen DHT. Changes in the steady state level of the nm23 and c-myc mRNA in LNCaP cells, with or without 10 nM DHT, showed the nm23 mRNA to change rapidly, beginning to rise after 2 h and reaching its peak by 4 h of DHT treatment. In contrast, increases in the c-myc gene only became apparent after 4 h of treatment. Maximal increase of nm23 mRNA was observed at 10(-9) M DHT. The basal expression of c-myc and nm23 mRNAs was between 30-70% lower in the LNCaP cells, as compared with the androgen-independent PC-3 and JCA-1 human prostatic human carcinoma cells. Thus nm23 may be classified as a member of the early androgen-responsive genes.

Cell Division↗
PubMed1995

Treatment of hepatitis B surface antigen carriers in the early stage of the infection using recombinant alpha-interferon with steroid priming.

BACKGROUND: Alpha-interferon has been found to inhibit hepatitis B virus (HBV) replication in Chinese patients with chronic HBV infection although a sustained effect was rarely achieved in those with normal pretreatment serum alanine amino transferase (ALT) levels. Prednisolone priming has been found to be beneficial over treatment with interferon alone in these subjects. We studied the effect of steroid pre-treatment followed by recombinant interferon alpha-2a in the treatment of asymptomatic HBV carriers with positive hepatitis Be antigen (HBeAg), hepatitis B viral DNA (HBV-DNA) and minimal changes in liver histology. METHODS: The treatment regimen included a 6-week prednisolone priming, a 2 week rest followed by 14 weeks of three times weekly 9 mega units of interferon alpha-2a injection and 52 weeks of follow-up. There were seven patients in the treatment group and seven controls. RESULTS: The mean age, pre-treatment ALT (normal in all except for one in each of the treatment and control groups), HBV-DNA levels and histological scores were similar in the two groups. Serum HBV-DNA levels fell in six patients during treatment and became undetectable in two of them by the end. During follow-up, serum HBV-DNA returned to pre-treatment levels in all patients. None of the treated patients had HBeAg sero-conversion and none of the controls had spontaneous clearance of HBV-DNA or sero-conversion of HBeAg. No improvement of liver histology was observed in any of the treated patients. There were only mild flu-like side-effects noted and interferon alpha-2a was well tolerated at the doses given among treated patients. CONCLUSION: Prednisolone priming followed by interferon alpha-2a treatment has no beneficial effect on HBV carriers in the early stages of chronic hepatitis B infection.

Adult↗
PubMed1995

The synthetic retinoid N-(4-hydroxyphenyl) retinamide (4-HPR) exerts antiproliferative and apoptosis-inducing effects in the androgen-independent human prostatic JCA-1 cells.

A significant reduction in JCA-1 cell proliferation was observed as a result of treatment with 4-HPR. This was accompanied by the down-regulated expression of the proliferating cell nuclear antigen PCNA, cyclins D and E, and p34cdc2. Unexpectedly, p53 and pRB was also suppressed in response to 4-HPR. A prolonged exposure to 4-HPR (6 days) promoted the appearance of non-adherent cells showing morphological features and DNA fragmentation patterns indicative of apoptosis.

Androgens↗
PubMed1995

Immunogenicity and safety of an inactivated hepatitis A vaccine amongst Singaporeans.

The immunogenicity and reactogenicity of an inactivated hepatitis A virus (HAV) vaccine was studied in healthy Singaporean adult volunteers. One hundred and forty healthy volunteers with normal alanine (ALT) and aspartate (AST) transaminases and no previous exposure to HAV, received three 1 ml doses (720 ELISA units) of an inactivated HAV vaccine (Smithkline Beechams Biologicals) following a 0, 1, 6 months vaccination schedule. All subjects were asked to record and grade the severity of any reactions for three consecutive days after each dose. Serum ALT and AST as well as anti-HAV were measured at 0, 1, 2, 6 and 7 months after the first vaccine dose. Anti-HAV seroconversion occurred when levels rose above 40 mIU/ml. Eighty-five percent of vaccinees seroconverted after the first innoculation and 99% after the second injection. All vaccinees seroconverted after the third dose. Geometric mean anti-HAV titers (GMTs) were, respectively, 119, 391, 4406 mIU/ml one month after each of the three doses. The most common side effect was transient pain and tenderness at the vaccination site. No elevation of ALT or AST levels were noted during the study period. The inactivated hepatitis A vaccine used in this study is safe and highly immunogenic in the local adult population. Two doses one month apart appeared to give adequate protection.

Adult↗
PubMed1994

Cyclooxygenase gene expression in human endometrium and decidua.

The objective of this study was to determine if genes for cyclooxygenase (COX) and 5-lipoxygenase, key enzymes in the synthesis of eicosanoids, are expressed in human endometrium and to determine if the level of expression is affected by decidualization or preeclampsia, a form of pregnancy-induced hypertension. RT-PCR was used to detect mRNA in tissues obtained from various patients. Results demonstrated that COX and 5-lipoxygenase genes are expressed in endometrium and decidua. COX gene expression in endometrium is 2-3-fold greater than in decidua while 5-lipoxygenase gene expression is similar. Neither COX nor 5-lipoxygenase gene expression in decidua is altered by changes resulting from preeclampsia. Thus, genes for key enzymes in the synthesis of eicosanoids are expressed in human endometrium and decidua. Selective down-regulation is evident as decidualization results in a significant reduction in the gene expression of COX, while 5-lipoxygenase gene expression remains unchanged.

Arachidonate 5-Lipoxygenase↗
PubMed1994

An analysis of referral routes and diagnostic accuracy in cases of suspected glaucoma.

Over a nine-month period two hundred and thirteen referrals to the Department of Ophthalmology of the Leicester Royal Infirmary, England, for suspicion of glaucoma were examined by a single ophthalmologist. Ninety-nine percent of referrals resulted from the findings at an optometric visit. Despite this, less than 32% were confirmed as having glaucoma and less than 23% had ocular hypertension. Twenty-nine percent showed no abnormality. Of those with glaucoma 19% showed advanced field loss in their worse eye. The guidelines relating to referral practices as a result of optometric examinations need to be reviewed and agreed upon by ophthalmologists, optometrists and general practitioners.

Adult↗
PubMed1993

Can a divided digital nerve on one side of the finger be left unrepaired?

72 fingers with divided digital nerves on one side alone had their nerves repaired and the sensory recovery assessed at different intervals of up to 2 years. Another 36 fingers with similar digital nerve injuries had their divided nerves left unrepaired and sensory recovery similarly assessed for comparison. In the "repaired" group, the result continued to improve and by 2 years, 90% reached S3+ or above. In the "unrepaired" group, improvement plateaued after 6 months, and at 2 years only 6% reached S3+ or above, although all had regained some protective sensibility.

Adolescent↗
PubMed1993

Hand function after digital amputation.

127 patients with amputated thumbs or fingers between the level of the DIP and MP joints were followed up at regular intervals until one year after injury. Sensory disturbances subsided rapidly except for numbness which was still present in 50% at one year. Range of movement was regained early. Although pronation and supination improved to 70% only a few months after injury, it took a year for power grip and key pinch to regain 70%. Further analysis showed that power grip was worst in amputees of multiple fingers, thumb, and the middle finger through the proximal phalanx. For key pinch, almost all were impaired to a level of 50% to 60%. Multiple finger amputees also had decreased pronation, and thumb amputees had decreased supination. Other factors were not significant. One-quarter had to change their jobs and one-fifth showed concern with the appearance.

Activities of Daily Living↗
PubMed1992

Polycystic liver disease with obstructive jaundice: treatment with ultrasound-guided cyst aspiration.

A 59-year-old woman with polycystic liver (PCLD) and kidney disease (PCKD) presented with jaundice, fever, and abdominal pain. A computered tomographic (CT) scan performed immediately after an endoscopic retrograde cholangiopancreatogram (ERCP) clearly demonstrated a hepatic cyst obstructing the biliary system. The cyst was then aspirated under ultrasound guidance with complete relief of obstruction.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1992

Cytomegalovirus gastritis: protean radiologic features.

Infection with cytomegalovirus (CMV) is a major feature of acquired immunodeficiency syndrome (AIDS). Gastrointestinal involvement is being seen more frequently. Our collective experience involves nine patients with stomach involvement. Seven patients were intravenous drug abusers or homosexuals with AIDS. One developed CMV gastritis as a complication of leukemia and one patient was a West African with lymphoma and human immunodeficiency virus (HIV) infection. All our patients had biopsy-proven CMV inclusion bodies. The radiographic appearances varied widely. The findings included markedly thickened edematous folds, erosive gastritis with aphthous ulceration, and superficial and deep ulceration. One patient had deep ulceration with fistula formation. Computed tomographic (CT) scans confirmed the greatly thickened gastric wall and coarsened folds in two patients. Associated gastrointestinal infections included candida and herpes, and, in addition, pneumocystis carinii pneumonia (PCP) was present in two patients. CMV gastritis may mimic several other conditions including erosive gastritis, peptic ulceration, lymphoma, and carcinoma. It should be strongly considered in immunosuppressed patients.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Early hepatic stages of Plasmodium berghei: release of circumsporozoite protein and host cellular inflammatory response.

After injection of Plasmodium berghei sporozoites into Norway-Brown rats, we were able to localize these sporozoites and the early hepatic trophozoites developing from them in histological sections of the liver stained with a sensitive immunogold-silver procedure. Sporozoites invading hepatocytes released substantial quantities of circumsporozoite protein into the hepatocyte cytoplasm. This intrahepatic cytoplasmic distribution reached a maximal level at about 4 h post-sporozoite injection. As the hepatic parasites continued to differentiate, circumsporozoite protein became undetectable within the cytoplasm of the hepatocytes and became localized around the periphery of each parasite. There was generalized cellular inflammation within the liver of the host, which first became evident at around 4 h post-sporozoite injection and progressed to the formation of well-defined granulomas by 24 h. Such histopathological changes were not seen in rats injected with killed sporozoites, indicating that the cellular inflammation was induced by viable, infective sporozoites. We did not observe cellular infiltration specifically associated with any of the developing hepatic stages that we observed, even up to 28 h post-sporozoite inoculation. These results indicate that viable sporozoites induced rapid and generalized hepatic inflammation in host rats. However, sporozoites that successfully invaded hepatocytes and then proceeded to develop further did not appear to be the target of inflammatory cells until a period beginning at around 40 h post-sporozoite inoculation.

Acute-Phase Reaction↗
PubMed1992

Partial weight bearing after operations for hip fractures in elderly patients.

Factors affecting a patient's ability to carry out partial weight bearing after operation for hip fracture were studied in 100 patients. Seventy-six were able to do so. Significant factors included the muscle power of the good limbs and the mental state, whereas age, body-weight and type of operation were not significant. Logistical regression analysis showed that it was possible to predict a patient's partial weight bearing potential by simply testing the left hand grip and the 'Set' test score.

Aged↗