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Biomedical subjects

C W Chan

Publications and source records attributed to C W Chan.

At least 91 records · Page 5Linked to original sources
PubMed1986

Carcinoma of the esophagus. An autopsy study of 231 cases.

Autopsy findings for 231 cases of carcinoma of the esophagus are presented. Cases with tumour resection constituted 57% of the series. Residual malignancy was present in 81% of all cases. Local residual or recurrent tumour was found in 53%, lymph node metastases in 65% and visceral metastases in 54% of cases. Intrathoracic lymph node metastases were present in 41% of patients after tumour resection and were probably significant in the failure of radical surgery. Adequate clearance of intrathoracic lymph nodes during radical surgery may reduce the incidence of tumour recurrence in this group of patients. Survival was poor in patients with or without resection of the primary tumour. Less than 12% were alive 1 yr after presentation. The average duration of dysphagia at presentation was 2.5 mth. The poor survival of our patients suggests that, by the time they presented clinically, the disease was already advanced. Early disease detection is important for a chance of cure in patients with esophageal cancer.

Adult↗
PubMed1985

Intestinal leiomyosarcoma in childhood.

A 4-month-old boy with leiomyosarcoma of the ileum presented to us with complete intestinal obstruction. Small gut resection was done. The child was well 9 months after surgery with no evidence of a recurrence.

Humans↗
PubMed1985

Case of angiosarcoma of the nasal passage of the horse--ultrastructure and differential diagnosis from progressive haematoma.

An angiosarcoma involving the right frontal and maxillary sinuses in a nine-year-old Thoroughbred mare was studied post mortem by light and electron microscopy. Important diagnostic features included malignant endothelial cells lining ill-defined vascular spaces, supported by other vasoformative elements. Rhabdomyoblasts were also found. The tumour is apparently rarely seen in the nasal passages of the horse.

Animals↗
PubMed1985

Methods of measuring energy utilization in broilers: effect of genetic line and presence of supplemental dietary fat.

A commercial line (CL) and genetically-selected lean (LL) and fat (FL) lines were fed a purified diet containing either 2% corn oil or 2% corn oil plus 7% animal-vegetable fat. Both diets contained 23% crude protein and 3150 kcal nitrogen-corrected apparent metabolizable energy (AMEn)/kg. Apparent fat digestibility (AFD), apparent metabolizable energy (AME), AMEn, true metabolizable energy (TME), and nitrogen-corrected TME (TMEn) were determined on birds fed ad lib or restricted to 25 g for 36 hr. The birds on the ad lib program were than killed for net energy of production (NEp) determination. Apparent fat digestibility increased (P less than .05) from 1 to 3 weeks of age for both diets. This resulted in significantly lower AME, AMEn, and TMEn at 1 week than at 3 weeks. True metabolizable energy was not affected (P greater than .05) by age. The AMEn and TMEn at 1 kg body weight were less precise on the restricted than on the ad lib program. The AME, AMEn, TME, and TMEn determined by ad lib feeding at 1 kg body weight were not affected by line (P greater than .05) by line or diet. However, AME and AMEn from the same program were affected by line and diet. Nitrogen-correction of ME was only necessary for TME on the restricted program. Net energy of production was only different (P less than .05) among lines. Because of its greater precision, the AME assay with ad lib-fed birds is the preferred assay, at least at a young age.

Adipose Tissue↗
PubMed1985

Effect of dietary fat supplementation on the carcass composition of three genetic lines of broilers.

Three genetic lines of broilers - a commercial line (Ross X Arbor-Acres), and lines selected for low abdominal fat (lean line), and high abdominal fat (fat line) were fed one of two isocaloric and isonitrogenous purified diets differing in total fat content (2 vs. 9%). Carcass composition (crude protein, ether-extract, ash, and total dry matter content) was determined on four broilers/line/diet at 21 days of age and at 1 kg body weight. Carcass protein and ether-extract were not significantly (P less than .05) affected by diet at 21 days of age or at 1 kg weight. Carcass ash was significantly (P less than .01) affected by diet at 21 days of age but not at 1 kg body weight. Genetic line of broiler significantly (P less than .05) affected carcass protein, ether-extract, and ash at 21 days of age and at 1 kg body weight. Lean line broilers had a significantly (P less than .05) higher percentage of carcass protein and a significantly (P less than .05) lower percentage of carcass ether-extract than the fat line or commercial broilers.

Adipose Tissue↗
PubMed1984

The controversy over the influence of static tilt on soleus motoneuron excitability in man.

The influence of static fore-aft body tilts on the excitability of the human soleus motoneuronal pool had been studied by mapping the H reflex amplitude as a function of head positions by two groups of investigators with different results. In 11 of 13 subjects studied, we (C.W.Y. Chan and R.E. Kearney, 1982, Neurosci. Lett. 33: 333-338) found that the H reflex was a minimum when the head was near the vertical position, and often increased as a sinusoidal function of tilt to a maximum of 60 degrees forward or backward. In contrast, I.G. Aiello, G. Rosati, G. Serra, V. Jugnoli, and M. Manca (1983, Exp. Neurol. 79: 18-26) reported a linear decrease in the H reflex amplitude in all their subjects when the body was tilted from the vertical to the horizontal supine position. The differences in these findings were discussed from the point of view of methodology and in light of recent animal and human studies.

H-Reflex↗
PubMed1983

Experimental microarterial grafts: freeze-dried allografts versus autografts.

A segment of the femoral artery from a Sprague-Dawley rat was removed and freeze-dried. It was then used as a graft for a defect in the femoral artery of another rat. The femoral artery on the other side of this recipient rat had a similar grafting procedure using a segment of its own femoral artery, thus acting as a control. The patency rate, histopathology and scanning electron microscopy studies showed that freeze-dried allografts behave in the same way as autografts in this experimental model. They were easy to preserve, readily available on rehydration and were somewhat easier to handle because of their mild rigidity.

Animals↗
PubMed1983

Comparison of the effectiveness of placebo, clomiphene citrate, mesterolone, pentoxifylline, and testosterone rebound therapy for the treatment of idiopathic oligospermia.

Forty-six subfertile men with idiopathic oligospermia were randomly assigned to 6 months of treatment with a placebo, clomiphene citrate (25 or 50 mg/day), mesterolone (100 mg/day), or pentoxifylline (1200 mg/day) or 4 months of testosterone enanthate treatment (100 or 250 mg on alternate weeks). Treatment with the placebo, mesterolone, pentoxifylline, and testosterone rebound therapy did not result in a significant increase in the mean sperm concentration or pregnancy in the partners. Clomiphene citrate at both dosages significantly increased the mean sperm concentration without improving sperm motility or morphology during the 6-month treatment period. Pregnancy rates of 36.4% and 22.2% were observed in partners of men receiving clomiphene citrate 25 mg/day and 50 mg/day, respectively. This study also illustrates the difficulties in identifying suitable patients for and assessing the efficacy of different treatment regimens.

Adult↗
PubMed1983

The healing of freeze-dried rabbit flexor tendon in a synovial fluid environment.

Deep flexor tendons from the forepaws of rabbits were removed and cut into two segments, sutured and freeze-dried. About one week later each tendon was placed in a knee joint of the same rabbit from which the tendon had been removed. At one, two, three and six weeks the tendons were retrieved and examined grossly, histologically and by electron microscopy. For comparison a control group using non freeze-dried tendons was also studied. Although there was evidence of central necrosis, superficial healing of the freeze-dried tendons occurred and was presumably due to cells from the synovial fluid.

Animals↗
PubMed1983

Effects of floor and cage housing of male turkeys on semen production and fertility of fresh and stored semen.

Broiler-type male turkeys housed in individual cages were compared with those housed in litter floor pens with respect to fertility, semen volume, concentration of spermatozoa, body weight, foot abnormality, and mortality. The effect of short-term storage of semen on fertility was also examined. There was no significant difference (P greater than .05) between the fertilities of the males in cages and those on floor when semen was diluted and inseminated fresh (92 vs. 88%) or diluted and stored for 6 hr at 15 (79 vs. 84%) or 3 C (77 vs. 85%). The males in cages produced as much semen as those on floor and with similar concentrations of spermatozoa. Those in cages had significantly (P less than 01) reduced body weight, higher incidence of foot abnormality, and higher percent mortality. Storage of semen for 6 hr reduced fertility.

Animals↗
PubMed1982

Influence of static tilt on soleus motoneuron excitability in man.

The influence of whole head-body rotations with respect to gravity on the excitability of the human soleus motoneuron pool, was studied by mapping the H reflex amplitude as a function of static head displacements. In most subjects, the H reflex reached a minimum when the head was near the vertical position (90 degrees), and often increased as a sinusoidal function of tilt in the sagittal plane. These changes were attributed to the tonic labyrinthine reflexes which, unlike some findings in decerebrate cats, generally increase the extensor tone of the human lower limb when the head is displaced from the upright position.

H-Reflex↗
PubMed1982

Is the functional stretch response servo controlled or preprogrammed?

Recent findings in humans and primates suggest that the long latency electromyographic (EMG) responses, evoked by opposing sudden limb displacements, might be mediated via a transcortical pathway. However, it is not clear whether these "late" responses are servo controlled or preprogrammed. We have addressed these questions in two interrelated experimental series. Firstly, the late EMG responses (termed the FSR) evoked in the ankle muscles of 8-12 normal human subjects were mapped as a function of displacement amplitude and velocity. Secondly, the FSR evoked by sustained ramp displacements (lasting 500 msec) were compared with those elicited by transient pulse displacements (lasting 60 msec) having entirely different amplitude and velocity profiles. The findings demonstrated a general lack of a systematic relationship between the characteristics of the initial component of the FSR and displacement parameters, although exceptions were noted in individual subjects. Furthermore, no marked difference was found in either the latency or the rise time of the FSRs evoked by ramp and pulse displacements. The similarity of the FSRs in spite of widely different input patterns is not consistent with the behaviour of a servo response. However, such a finding is in agreement with the concept of a preprogrammed pattern of activity which, once triggered, has to run its full course without the possibility of modification. It is therefore concluded that, at least the initial part of the FSR is generated by the triggered release of a preformulated pattern of intended movement relatively independent of the specific pattern of limb displacement, rather than acting in the manner of a servo mechanism.

Ankle↗