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Biomedical subjects

C W Chan

Publications and source records attributed to C W Chan.

At least 73 records · Page 4Linked to original sources
PubMed1991

Quantitative analysis of the accuracy of linear array transrectal ultrasound in measurement of the prostate.

In 61 prostate autopsy specimens, linear array transrectal ultrasound and electronic vernier calipers were used to measure 3 maximal diameters along the longitudinal, anterior-posterior and transverse axes. The results were comparable. We assessed the reliability of empirical formulae, derived from various combinations of these 3 diameters, for the prediction of prostatic volume and weight. Formulae using all 3 diameters were accurate. The combination of longitudinal and anterior-posterior diameters, which was used clinically for prostate measurement, was less accurate.

Anthropometry↗
PubMed1991

Effect of feeding palmitic, oleic, and linoleic acids to Japanese quail hens (Coturnix coturnix japonica). 1. Reproductive performance and tissue fatty acids.

A study was conducted to evaluate the effects of diets containing 3% of either palmitic acid (Diet PA), oleic acid (Diet OA), or linoleic acid (Diet LA) on reproductive performance, fatty acid composition of egg yolk, plasma, and liver, and total plasma phosphorus of Japanese quail. Each diet was fed to 20 individually caged hens from 5 wk of age. A 24-wk production period started at 8 wk of age. Fertile eggs for incubation were obtained by placing at random a male in the cage with the female for 15 to 20 min twice per week. The males were kept in separate individual cages and fed a turkey grower diet throughout. Feed consumption, egg production, egg output, and the number of chicks per hen were higher (P less than .05) in birds fed Diet PA than in those fed Diet OA or Diet LA. Hatchability was not different (P greater than .05) between Diet PA and Diet OA, but they were higher (P less than .05) than that of Diet LA. Quail weight at hatch from birds fed Diet LA was heavier (P less than .05) than those from Diet OA, but not different (P greater than .05) from those fed Diet PA. Total plasma phosphorus concentration was higher (P less than .05) in birds fed Diet PA than in those fed Diet LA. High levels of oleic and linoleic acids were found in egg yolk, plasma, and liver lipids from birds fed Diet OA and Diet LA, respectively. Feeding Diet PA resulted in elevated levels of palmitoleic acid in all three tissues. The highest overall reproductive performance on Diet PA suggests that palmitic acid has some physiological role in reproduction. The sustained near-maximal levels of egg production and fertility achieved in this trial indicate the superiority of the mating procedure, which would also permit testing the response of male and female birds while minimizing injuries incurred by the females.

Animal Feed↗
PubMed1990

Dissecting aneurysm of coronary artery presenting as cardiac tamponade.

Primary dissecting aneurysm of the coronary arteries usually presents as sudden death or complications of myocardial infarction. The most common site of the dissection has been the anterior descending branch of the left coronary artery. A Chinese woman with primary dissecting aneurysm of the right coronary artery presenting as cardiac tamponade is reported. This is the first case of ruptured coronary aneurysm reported in the Chinese and the only case presenting as cardiac tamponade since 1931.

Aortic Dissection↗
PubMed1990

Nasopharyngeal carcinoma. Pattern of tumor regression after radiotherapy.

The primary tumor regression pattern of 50 patients with nasopharyngeal carcinoma was reported. The tumor regression was monitored either by indirect nasopharyngeal mirror examination and biopsy or fiberoptic endoscope and biopsy. Fiberoptic endoscope and biopsy was found to be more accurate in noting residual tumor. It is recommended that booster radiation dose to the residual primary tumors be withheld unless positive biopsy samples persist at 10 or more weeks after radiotherapy.

Biopsy↗
PubMed1990

Age-related glomerular sclerosis: baseline values in Hong Kong.

A study was undertaken to estimate the incidence of glomerular sclerosis in the normal population in Hong Kong. The percentage glomerular sclerosis in 100 cadavers without clinical evidence of kidney disease or hypertension was determined by histologic examination of the kidneys. The mean percentage values in the normal population at all age groups were calculated based on this sample. The subcapsular cortical area generally had a higher proportion of sclerotic glomeruli than the deeper cortex. Statistical analysis showed that 95% of the normal population up to 40 years of age would be expected to have less than 6% sclerotic glomeruli. After the age of 55, the upper limit containing 95% of the normal population would exceed 10% sclerosis. A broad scatter of observed percentage glomerular sclerosis was present in the elderly after the age of 70 years. The data obtained provide the baseline values of glomerular scarring that would allow age-related involutional changes to be distinguished from those due to disease.

Adolescent↗
PubMed1990

The influence of supplemental corn oil and free fatty acids on the reproductive performance of Japanese quail (Coturnix coturnix japonica).

An experiment was conducted to evaluate the effects of dietary corn oil (CO) and commercial free fatty acids on the fatty acid composition of blood plasma and egg yolk lipids and on the reproductive performance of Japanese quail. When quail were fed a semi-purified low-fat basal mix, the substitution of 3% of CO for corn starch (CS) improved egg weight (11.2 versus 10.8 g), reduced late embryonic mortality (16.7 versus 28.4%), and improved hatchability (75.7 versus 64.1%). Diets in which palmitic acid or oleic acid were substituted on a weight basis for 3% of CS performed as well as those in which CO was used. When linoleic acid replaced 3% of CS, late embryonic mortality was reduced (13.7 versus 28.4%) and hatchability was improved (80.1 versus 64.1%), but fertility was depressed (85.8 versus 93.6%). The substitution of linolenic acid for 3% of CS depressed feed consumption, body weight, and egg weight relative to the low-fat CS diet and did not improve the low 18-day embryonic livability and low hatchability. The fatty acid compositions of plasma and yolk were influenced by the lipid composition of the diets. Quail fed 3% of CO deposited more linoleic acid in the egg than those fed 3% of linoleic acid (15.2 versus 11.7%). Thus, quail fed a simplified basal breeder diet containing .6% of linoleic acid showed decreased embryonic livability and hatchability and these parameters achieved normal levels in response to the substitution of 3% of either CO, palmitic acid, oleic acid, or linoleic acid for CS.

Animals↗
PubMed1989

Fiberoptic endoscopic examination and biopsy in determining the extent of nasopharyngeal carcinoma.

This is a prospective study on the use of flexible endoscope and multiple biopsies in the assessment of nasopharyngeal carcinoma in 72 patients. This study confirmed the presence of submucosal growth pattern in nasopharyngeal carcinoma in 72 patients. This study confirmed the presence of submucosal growth pattern in nasopharyngeal carcinoma and this occurred in 13.8% of patients. Occult microscopic extension of tumor not detectable by fiberoptic endoscopy occurred in another 51.4% of patients. It has also been shown that multiple biopsy is superior to clinical examination in evaluating the extent of disease in nasopharyngeal carcinoma. Multiple biopsies are suggested for the early detection of nasopharyngeal carcinoma in high-risk cases. Although the better-defined tumor extent do not currently influence the treatment policy of nasopharyngeal carcinoma, and it is too early to assess its prognostic significance, it betters our understanding of the behavior of this tumor. Future analysis in correlation with long-term follow-up data may help to improve the stage classification systems and treatment strategy.

Biopsy↗
PubMed1989

Colorectal carcinoma in Hong Kong Chinese. A pathological survey of 1,117 cases, 1972-1981.

Hong Kong Chinese, when compared with the world population, have an intermediate incidence rate for colorectal carcinoma. The purpose of this retrospective analysis of a large number of colorectal carcinomas (1,117 cases) was to explore possible differences between this series and others, and to re-examine the divergent features reported in a smaller series. The present study revealed a distribution by age, sex, site and Dukes' stage, as well as histopathological features, which were analogous to those reported from other countries. Thus, while the incidence is lower in this group, the other manifestations of the disease are very similar to those seen elsewhere. The implication is that, apart from varying incidence, there is a global similarity among colorectal tumours.

Adult↗
PubMed1989

Subjective pain sensation is linearly correlated with the flexion reflex in man.

In an attempt to define the relationship between physiological and psychological correlates of pain during low-level voluntary contraction, electrical stimuli between threshold and maximally tolerable intensities were delivered to the sole of the foot in 7 normal subjects. The two measures used to assess the response magnitude are: (1) the flexion reflex (FR) in the ipsilateral biceps femoris (BF), and (2) the estimate of perceived intensity reported on a visual analog scale (VAS). Our results showed that both BF FR area and VAS ratings bore a direct linear relationship with stimulus intensity and with each other, suggesting that at least under our paradigm, the sensory component of a nociceptive stimulus may already be largely set at the spinal interneuronal level.

Adult↗
PubMed1989

In situ detection of Epstein-Barr virus markers in nasopharyngeal carcinoma patients.

Cryosections of nasopharyngeal tissue from 9 patients suspected of having nasopharyngeal carcinoma (NPC) were examined for the presence of Epstein-Barr virus (EBV) markers in situ to assess virus infection in the nasopharynx. Viral DNA, EB nuclear antigen, and/or early antigens (EA.D and EA.R) were detected in 5 NPC specimens. EBV infection was not confined to the tumor areas of the biopsy specimens. Lymphoid cells and nontumor areas of these specimens contained EBV markers. In addition, nasopharyngeal tissues obtained from 3 of 4 patients in clinical remission for the disease showed evidence of EBV infection.

Antibodies, Monoclonal↗
PubMed1988

Motor planning is impaired in Parkinson's disease.

Reaction times (RTs) were assessed in parkinsonian and normal subjects under simple ballistic (bRT), simple tracking (tRT), and choice tracking (CRT) ankle plantarflexion RT paradigms. While RTs were prolonged in both groups for tracking versus bRT movements, between-group differences were not detectable for the simple RT (either ballistic or tracking) tasks. In contrast, parkinsonians demonstrated significantly greater CRT and CRT-bRT delays than normals, suggesting that parkinsonian akinesia may involve a disturbance in central processing related to motor planning.

Aged↗
PubMed1987

Evaluation of monoclonal antibodies for the detection of exfoliative nasopharyngeal carcinoma cells.

Exfoliative cells were aspirated from 15 patients suspected of having nasopharyngeal carcinoma (NPC) and showing the presence of lesions or other abnormalities in the nasopharynx. They were tested for binding with a 125I monoclonal antibody (MAb) (MA6) which is selectively reactive against human B lymphocytes and a variety of carcinomas. A positive result was obtained from 6/9 patients with, and from 0/5 patients without, histologically confirmed disease. One patient with eskimoma also gave a negative binding result. Cytology was specific but less sensitive, tumour cells being detected in 3 of the patients with confirmed disease. Immunocytology using MA6 was limited, like cytology, by poor recovery of the tumour cells and the results were in complete concordance with cytology. The other MAbs used were raised against carcinoembryonic antigen (CEA) and a carcinoma cell line (Ca2), respectively. The latter was not reactive against the NPC tumour cells while the CEA antibody was not sufficiently selective to be useful.

Adult↗
PubMed1987

Characterization of a murine monoclonal-antibody-defined B-lymphocyte carcinoma cross-reacting antigen (BLCa) from nasopharyngeal carcinoma tissues.

Biopsies were obtained from 12 patients suspected of having nasopharyngeal carcinoma (NPC). A portion of the tissue was submitted for histopathology and another for Western blotting using a murine monoclonal antibody (MAb), MA6. Touch smears of the tissues were also prepared immediately prior to extraction and Western blotting for immunoenzymic staining. The results showed that a B-lymphocyte carcinoma cross-reacting antigen (BLCa), or an antigen similar to it, was the major antigen in the tumor tissue recognized by MA6. The antigen was detected in tissues from 8 patients, of whom 7 had confirmed NPC and one had eskimoma, but not in tissue from the remaining 4 patients who did not have histologically confirmed malignancy. Immunocytology showed that tumour cells were present in the touch smears from all but one of the tumour patients but not in the other patients, and that the tumour cells comprised the large majority of the MA6-reactive cell population. The other MA6-reactive cell types present included certain weakly reactive epithelial cells and occasional lymphoid cells, presumably B lymphocytes. However, these cell types were similarly distributed between the tissues obtained from patients with or without malignant diseases. It was concluded, therefore, that the tumour cells in these tissues are the principal source of BLCa and, as such, the antigen may constitute an objective and reliable marker of NPC.

Animals↗
PubMed1986

Telangiectatic osteosarcoma of the mandible.

A telangiectatic variant of osteosarcoma of the mandible was seen in a 15-year-old Chinese girl. It was first diagnosed as an aneurysmal bone cyst both radiologically and pathologically. There were local recurrences despite repeated surgery, and subsequent response to chemotherapy and radiotherapy was poor. The patient died 16 months later with direct cerebral invasion, but no distant metastases. Diagnostic and clinicopathologic correlative aspects of this tumor variant are discussed, but more study of this tumor variant in the jaw is needed because this is probably the first case fully reported.

Adolescent↗
PubMed1986

Could parkinsonian akinesia be attributable to a disturbance in the motor preparatory process?

To test the hypothesis that parkinsonian akinesia could be due to a disturbance in motor preparatory process, we measured the extent to which the normal pattern of H-reflex excitability prior to a ballistic movement, in a simple reaction time (RT) paradigm, is modifiable by akinesia. Nine age-matched normals and 11 parkinsonians were examined. They were instructed to plantarflex their ankle rapidly in response to a visual signal (RS) following a bleep (WS), while EMGs were recorded from soleus and tibialis anterior (TA) simultaneously with ankle position. Under this 'control' condition: mean soleus EMG and movement RTs were significantly longer in parkinsonians than normals. Given no evidence of fatigue or other effects, this finding indicated that our patients were akinetic. Furthermore, the normal pattern of agonist-antagonist bursts was often delayed, reduced or prolonged in these patients. Next, we measured changes in soleus motoneuronal pool excitability at 4 predetermined intervals relative to the RS but prior to EMG onset, by means of H-reflex testing. Three findings emerged: mean soleus EMG and movement RTs were again significantly delayed in parkinsonians. However, no intersensory facilitation/inhibition of the RTs occurred between H-reflex and visual stimuli, in that these values remained unchanged within the group, despite the addition of H-test stimulation. More importantly, facilitation of H-reflex was similarly time-locked to EMG onset for the two groups, with increases in H-reflex amplitude commencing some 60 ms prior to agonist discharge. Bearing in mind the prolonged RTs in parkinsonians, these findings pointed to a delay in the facilitation of the H-reflex relative to the RS as a cause of akinesia. Our proposition that parkinsonian akinesia could be attributable to an impairment in the motor preparatory process therefore remains a tantalizing possibility.

Aged↗