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Biomedical subjects

C M Yuan

Publications and source records attributed to C M Yuan.

23 records · Page 2Linked to original sources
PubMed1989

Computed tomography in the management of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is one of the common cancers in China. According to mass surveys, the incidence of NPC in some areas of Guangdong is 39.84/100,000. Due to its high contrast resolution CT has the ability to show not only superficial abnormality but also deep infiltration of the fasciae and muscles of the parapharyngeal region. Computed tomography scanning was performed on more than 1000 patients with NPC in the Tumour Hospital in the 2 years from 1984 to 1986. The role of CT scanning in NPC can be summarised as: (1) detection of primary lesions not accessible to pharyngoscopy; (2) determination of the extent of disease; (3) clinical staging; (4) radiotherapy planning; (5) follow up evaluation; (6) the differentiation of recurrence and radiation damage to the brain; and (7) the demonstration of distant metastasis. In contrast to the concept of jugular chain metastasis via the postero-lateral pharyngeal lymph nodes, our material has demonstrated that the lesion most probably spreads to the carotid sheath area directly from the pharyngeal lesion. The tendency of submucosal spread of NPC is emphasised.

Carotid Arteries↗
PubMed1988

Regional heterogeneity in the distal motor axon: three zones with distinctive intrinsic components.

In this study we examined the distribution of cytoskeletal and other intrinsic axonal elements in motor nerve terminals in vivo. Components of axons were visualized with immunocytochemical staining of frozen longitudinal sections of muscle. Using these methods we compared the distribution of neurofilaments, tubulin, MAP2, actin and synaptic elements in distal regions of axons at and near neuromuscular junctions in rat muscles. Our results show that three discrete regions can be defined based on the anatomy and intrinsic components of distal axons. The preterminal axon, extending from its exit from the intramuscular nerve toward the neuromuscular junction, has a cytoskeletal composition similar to the more proximal axon with abundant staining of neurofilaments, tubulin, MAP2 and actin. The terminal arborization, a branched region of the axon extending through the endplate region, contains neurofilaments but little tubulin, actin, MAP2 or synaptic elements. Finally, the synaptic zone, demonstrated with antibodies to the synaptic vesicle protein synaptophysin, contains few cytoskeletal elements. We conclude that there is considerable regional heterogeneity in the composition of distal motor axons. The distribution of neurofilaments, other cytoskeletal elements and synaptic vesicle proteins varies among different discrete zones of terminal motor axons.

Animals↗
PubMedDate not supplied

The impact of bleeding times on major complication rates after percutaneous real-time ultrasound-guided renal biopsies.

BACKGROUND: Previous studies have shown that bleeding times have positive predictive values of only 5% for perioperative bleeding in unselected populations. Nevertheless, performing bleeding times prior to all renal biopsies is common in nephrology practice. METHODS: We report complications of 112 renal biopsies done at Walter Reed Army Medical Center (WRAMC) from 1996-99 performed without preceding bleeding times. Renal biopsies were done only on normotensive (<140/90) patients who had not recently been taking aspirin or non-steroidal anti-inflammatory agents, under real-time ultrasound guidance with automated 16 g (WRAMC) spring-loaded guns. High-risk patients (with serum creatinine > or = 3 mg/dl or creatinine clearance < or =30 cc/min by Cockroft-Gault formula, N=18, 16%) at WRAMC were treated with pre-renal biopsy estrogens or DDAVP. Factors were tested for their association with complications after renal biopsy using Chi Square testing for categorical variables and student's t-test for continuous variables. A stepwise logistic regression model was used to test for independent significance of factors. RESULTS: There were two cases each of gross hematuria and inadequate tissue (1.8% each). There were no transfusions or deaths. In univariate analysis, male gender and lower serum creatinine level at time of biopsy were significantly associated with increased risk of complications after biopsy. However, these factors were not significant in logistic regression analysis. CONCLUSION: This study suggests that the use of bleeding times does not significantly alter the major complication rates associated with percutaneous real-time ultrasound guided renal biopsy.

Adolescent↗
PubMedDate not supplied

The impact of renal transplantation on the incidence of congestive heart failure in patients with end-stage renal disease due to diabetes.

BACKGROUND: Patients with end stage renal disease (ESRD) are at increased risk for cardiovascular disease. We hypothesized that the clinical incidence of congestive heart failure (CHF) would be lessened after successful renal transplantation, as many of the metabolic and intravascular volume abnormalities associated with dialysis-dependent ESRD would resolve. METHODS: Using data from the USRDS, we studied 11,369 patients with ESRD due to diabetes enrolled on the renal and renal-pancreas transplant waiting list from 1 July 1994-30 June 1997. Cox non-proportional hazards regression models were used to calculate adjusted, time-dependent hazard ratios (HR) for time to the most recent hospitalization for CHF (including acute myocardial infarction, unstable angina, or other CHF, ICD9 Code 428.x) for a given patient in the study period, controlling for both demographics and comorbidities in the medical evidence form (HCFA 2728). RESULTS: In comparison to maintenance dialysis, renal transplantation was independently associated with a lower risk for CHF (HR 0.64, 95% confidence interval, 0.54-0.77) in a model including age, gender, race, and year of first dialysis, but not in a model including comorbidities from the medical evidence form, although the sample was much smaller. CONCLUSIONS: Patients with ESRD due to diabetes on the renal transplant waiting list were much less likely to be hospitalized for congestive heart failure after renal transplantation, despite post transplant complications due to immunosuppression.

Adult↗