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Biomedical subjects

H M Cheng

Publications and source records attributed to H M Cheng.

At least 37 records · Page 2Linked to original sources
PubMed1998

OphthWeb---cost-effective telemedicine for ophthalmology.

'OphthWeb' is an ophthalmic electronic medical record that can be accessed locally and globally via the Internet. OphthWeb can provide secure multimedia patient data to doctors, patients, and health care providers at any time and in any place. Patients have secured access to their own records in the convenience of their homes or during any emergency at any time or place around the world. OphthWeb provides interactive educational information and answers frequently asked questions by way of multimedia images on the Worldwide Web. A data transmission trial was conducted between the Xiamen Eye Centre in the Fujian province in southern China and Singapore. Clinical records, voice messages, and fundus and slit-lamp images were transmitted from Xiamen, and an off-line dialogue by e-mail and Internet-relay chat was conducted. The time delay from transmission to receipt was 30 minutes, which would be adequate to respond to most ophthalmic emergencies. This pilot project will promote computer literacy among doctors, and inter-institutional interaction in the health care profession. OphthWeb can provide telemedicine and electronic medical records at a low cost and great convenience.

Journal Article↗
PubMed1998

An investigation of aeroallergens affecting urban Malaysian asthmatics.

We investigated the aeroallergens affecting 200 asthmatics from the University Hospital in Kuala Lumpur, Malaysia and found 164 (82%) patients with skin prick test (SPT) reactivity to one or more of a panel of 14 allergens, which included indoor and outdoor animal and plant aeroallergens. Reactivity was most frequent to the indoor airborne allergens, with 159 (79.5%) reacting to either or both house dust mite (Dermatophagoides) species and 87 (43.5%) to cockroach. The SPT reactivity to house dust mites corresponded with the finding that patients found house dust to be the main precipitant of asthmatic attacks.

Air↗
PubMed1997

Magnetic resonance imaging of cyclodialysis clefts.

BACKGROUND: Our purpose was to determine whether cyclodialysis clefts can be imaged with magnetic resonance imaging (MRI). METHODS: Surgical cyclodialysis clefts extending approximately 3 clock hours were created in four New Zealand white rabbits. Eyes were scanned with an ocular MRI coil. Images obtained after intravenous gadolinium, topical godalinium, and gadolinium injected into the cleft were compared to images obtained without contrast. Two human eyes were also scanned for cyclodialysis clefts with MRI. RESULTS: Direct injection of gadolinium into the suprachoroid space yielded definitive localization and delineation of the cyclodialysis cleft. Cyclodialysis clefts could also be imaged following enhancement with topical or intravenous gadolinium. Without contrast medium, the clefts could not be clearly identified in rabbits. In a patient with hypotony and choroidal effusion following cataract surgery, a cyclodialysis cleft and enhancement of the suprachoroidal space were found with intravenous administration of gadolinium. MRI from a patient with a trabeculo-suprachoroidal shunt also demonstrated gadolinium enhancement of the suprachoroidal space. CONCLUSION: Cyclodialysis clefts can be imaged using gadolinium-enhanced MRI in rabbits and humans.

Aged↗
PubMed1997

Gall-bladder wall thickening in patients with liver cirrhosis.

Gall-bladder wall thickening is commonly seen in patients with cirrhosis, but its exact causes have not been well established. We evaluated clinical, biochemical and haemodynamic data of patients with cirrhosis with respect to the presence of thickening of the gall-bladder wall. After excluding patients who presented with gallstones, acute or chronic cholecystitis, heart failure, a serum creatinine level greater than 2 mg/dL and/or a serum alanine aminotransferase level greater than 400 U/L, 77 patients with cirrhosis (75 male, two female; mean age 58 +/- 8 years) were enrolled in the study. Clinical, biochemical, ultrasound and haemodynamic data were obtained in every patient. Forty-one (53%) of 77 patients with cirrhosis had gall-bladder wall thickening (> 4 mm). Compared with patients with a normal gall-bladder wall, patients with gall-bladder wall thickening had significantly lower serum albumin levels (3.6 +/- 0.6 vs 2.9 +/- 0.7 gm/dL, respectively; P < 0.05), a longer prothrombin time (13 +/- 6 vs 16 +/- 6 s, respectively; P < 0.05), more patients with Child-Pugh class C (6 vs 37%, respectively; P < 0.05) and more patients with ascites (8 vs 50%, respectively; P < 0.05). In addition, compared with patients with a normal gall-bladder wall, those patients with gall-bladder wall thickening had a higher hepatic venous pressure gradient (13.9 +/- 4.5 vs 17.1 +/- 4.1 mmHg, respectively; P < 0.01) and a lower systemic vascular resistance (SVR; 1144 +/- 332 vs 1010 +/- 318 dyn.s/cm5, respectively; P < 0.05). Using a multivariate analysis, the presence of ascites and SVR lower than 900 dyn.s/cm5 were independently correlated with the presence of gall-bladder wall thickening, while a hepatic vein pressure gradient greater than 10 mmHg had only a marginally significant association. The presence of ascites, decreased SVR and portal hypertension are related to the occurrence of gall-bladder wall thickening in patients with cirrhosis, indicating that the development of gall-bladder wall thickening may be multifactorial.

Ascites↗
PubMed1997

Primary hyperparathyroidism with cardiac abnormalities: a case report.

Primary hyperparathyroidism, characterized by hypersecretion of parathyroid hormone (PTH) leading to hypercalcemia and relative hypophosphatemia, is quite common in the elderly. Most patients with primary hyperparathyroidism have only mild hypercalcemia and are symptomless. But others experience various other organ diseases. Primary hyperparathyroidism is also associated with cardiovascular abnormalities, including QT interval shortening, heart block, cardiac arrhythmias, hypertension, myocardial hypertrophy, myocardial calcification and, though rarely, with valvular heart disease. We described a case of primary hyperparathyroidism associated with cardiac abnormalities. An 82-year-old male presented with the complaints of chest discomfort, fatigue, general weakness, nausea and vomiting over a period of months and was admitted in July 1996. Physical examination with heart auscultation showed a pansystolic murmur over the right sternal border and apex region, and a blowing diastolic murmur over the left sternal border. Biochemistry profiles revealed elevations of serum calcium (14.3 mg/dl) and chloride/phosphate ratio (> 33). Endocrinological studies showed elevations of serum PTH-C (4.8 ng/ml) and PTH-intact (705 pg/ml) concentrations. Kidney ultrasonography revealed a left renal stone. A spine X-ray revealed spondylosis and a compression fracture of the lumbar-spine with osteoporotic change. Thyroid ultrasonography and Thallium (Tl201)-technetium (Tc99m) subtraction scan showed parathyroid adenoma in the low pole of the right thyroid bed. Parathyroid aspiration cytology revealed few and discrete cells. Echocardiogram revealed moderate to severe aortic valvular calcification as well as stenosis with moderate aortic regurgitation, mitral regurgitation and myocardial calcification. The patient received parathyroidectomy one month later. During his postoperative days, he suffered from muscle twitching with positive Trousseau's sign and Chvostek's sign. The patient received calcium carbonate and vitamin D for hypocalcemia, diltiazem and capoten for his heart problems. A repeated echocardiogram two months after surgery showed no improvement of valvular calcification.

Aged↗
PubMed1996

The further metabolism of sorbitol-3-phosphate and fructose-3-phosphate in the mature rat lens.

Glucose and phosphorus metabolism in mature (8-month-old) rat lenses were examined with NMR spectroscopy. Nondiabetic mature lenses contained sorbitol-3-phosphate (S3P) and fructose-3-phosphate (F3P) which were absent from young (1- to 2-month-old) normal rat lenses. The concentrations of these two phosphates can be changed through (1) diabetes induction with streptozotocin - this results in a dramatic increase in both compounds; and (2) oral dosing with a drug known to prevent sorbitol production - both metabolites disappeared. When normal mature lenses were incubated in 35.5 mM 13C1-glucose, both 13C1-lactate and 13C3-lactate were produced. Preservation of the 13C label at C1 is likely through the formation of 13C1-S3P and -F3P, which were then split through an aldolase-like mechanism into two 3-carbon compounds, one an unlabeled glycerol and the other 13C1-alpha-glycerophosphate (from S3P) and 13C1-dihydroxyacetone phosphate (from F3P). These reactions can contribute to the increase in alpha-glycerophosphate observed in both the streptozotocin-induced diabetic lenses and lenses incubated in high glucose.

Aging↗
PubMed1996

Nuclear magnetic resonance studies of sugar metabolism in the human infant lens.

We investigated sugar metabolism in lenses isolated from infants with stage-5 retinopathy of prematurity (ROP). The lenses were incubated in 13C-labeled glucose (35.5 mM) or galactose (30 mM) for 24 h at 37.5 degrees C. Six to 8 lenses were pooled for each experiment. 13C-nuclear magnetic resonance spectroscopy was then performed on perchloric acid extracts of these lenses. Active aldose metabolism was indicated by the production of lactate. However, neither sorbitol nor dulcitol was detected. On the other hand, an experimental aldose reductase inhibitor, sorbinil, caused a decrease in the hexose monophosphate shunt activity suggesting an active polyol pathway. Both polyols therefore appeared to have been metabolized further. In addition, galactose metabolism was unique in that it not only involved a galactose-->glucose epimerization, but also a direct galactose-->ribose conversion, and a production of galactose-3-phosphate. Although it is possible that the ROP lenses have adapted to oxidative stress during the postnatal high-oxygen incubation for premature infants, we believe the observed sugar metabolism is representative of the developing human lens.

Aldehyde Reductase↗