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Biomedical subjects

W Shen

Publications and source records attributed to W Shen.

At least 235 records · Page 13Linked to original sources
PubMed1991

[Quantitative analysis of coronary arteriogram by a computer-assisted method].

A computer-assisted method for quantitating coronary arteriograms was applied to measure the diameter of major epicardial coronary arteries in 58 normal subjects and 25 hypertensive patients, and to determine the percentage of relative stenosis of coronary lesions in 109 patients with coronary artery disease. Average coronary size was larger than normal in patients with hypertension. The left coronary artery was larger than the right coronary artery in the majority of patients. The degree of coronary stenosis can be measured accurately with good reproducibility. Thus this inexpensive microprocessor system provides rapid quantitation of coronary artery diameter and lesions.

Angina Pectoris↗
PubMed1990

Presenting the diagnosis of pseudoseizure.

Simultaneous video-EEG monitoring has allowed pseudoseizures to be effectively diagnosed. Discussing the results of the monitoring with the patient is the 1st step in treatment. We outline a protocol for presenting the diagnosis of pseudoseizure with the goal of conveying to the patient the importance of knowing the nonepileptic nature of the spells and the need for psychiatric follow-up. The protocol also allows elicitation of sexual abuse history and the use of suggestion to aid in controlling the pseudoseizures.

Clinical Protocols↗
PubMed1990

[Changes in left ventricular volumes after acute transmural myocardial infarction: clinical, angiographic and prognostic correlations].

The relation of left ventricular (LV) volume changes to clinical and angiographic features was assessed in 57 patients with a first transmural myocardial infarction. LV volumes were measured by two-dimensional echocardiography within 72 hours of admission and repeated at one month. The infarct-related artery (IRA) patency and collateral circulation were determined by coronary arteriography performed before discharge. LV end-diastolic and end-systolic volumes increased (155 +/- 44 vs 203 +/- 65 ml; 96 +/- 32 vs 134 +/- 57 ml, all P less than 0.01), and ejection fraction decreased (0.38 +/- 0.06 vs 0.34 +/- 0.09, P less than 0.05) in patients with totally occluded IRA without collaterals. In contrast, LV volumes and systolic function were unchanged in those who had subtotally occluded IRA or with collaterals. LV dilation (greater than or equal to 20% increase in LV end-diastolic volume) occurred more frequently in patients without residual flow to the infarct region (77%) than in those with (9%) (P less than 0.01). Thirteen patients with LV dilation developed congestive heart failure, 3 of whom having cardiac death. However, congestive heart failure was found in only 11 patients without LV dilation and no death occurred. Thus, the cardiac event rate was higher in patients with (65%) than in those without (30%) LV dilation (P less than 0.05). The study indicates that the changes in LV volumes following acute myocardial infarction are largely related to the status of residual flow to the infarct region and affect the clinical outcome of the patients.

Adult↗
PubMed1990

HIPDM-SPECT brain imaging in the presurgical evaluation of patients with intractable seizures.

We report the results of interictal and ictal HIPDM-SPECT brain imaging in 34 patients who eventually underwent temporal lobectomy for treatment of medically intractable complex partial seizures. Interictal studies revealed decreased regional cerebral perfusion (rCP) in the temporal lobe corresponding to the eventual site of surgery in 73% of the patients. Similarly, ictal study demonstrated increased rCP in 93% of the patients. In 69% of the patients, the SPECT studies were able to demonstrate both increased rCP on the ictal scan and decreased rCP on the interictal scan in the same location, corresponding to the eventual site of surgery. These results suggest that interictal and ictal SPECT brain imaging can be easily obtained and provide reliable localizing information in the presurgical evaluation of patients with medically intractable epilepsy.

Adolescent↗
PubMed1989

The efficacy of triclabendazole (Fasinex) against immature and adult Fasciola hepatica in experimentally infected cattle.

Eighteen Chinese cattle were experimentally infected with metacercariae of Fasciola hepatica and randomly assigned to 6 groups. Five groups of cattle were treated with a single oral dose of triclabendazole at a dose rate of 12 mg kg-1. At necropsy, the reduction in fluke burden compared with the untreated group was 85, 99.6, 99.8, 100 and 100% for cattle treated 2, 6, 8, 12 and 16 weeks after infection, respectively. Data are also presented on body weight changes during the experimental period and on serum gamma-GT activity in cattle from selected groups. Triclabendazole is considered to be safer and more efficacious than currently available fasciolicides in China.

Animals↗
PubMed1989

Disappearance of exogenously administered human chorionic gonadotropin.

Concentrations of human chorionic gonadotropin (hCG) were measured after intramuscular hCG administration in 34 patients undergoing ovarian stimulation in an in vitro fertilization program. Serum hCG levels were detectable by an immunoenzymetric assay up to 14 days after injection. Individual variation in hCG concentration after injection could be minimized by expressing the daily hCG level as a fractional distribution of the value observed 36 hours after hCG administration (hCG0). In nonpregnant patients, less than 10% of the hCG0 value was found on day 10. The disappearance rate measured 36 hours after injection of hCG was exponential with a mean half-life of 2.32 days. These findings are significant for ovarian stimulation protocols, including exogenous hCG, with respect to timing and accuracy of quantitative pregnancy testing.

Adult↗
PubMed1989

[A preliminary study on serum alpha-L-fucosidase assay in the diagnosis of hepatocellular carcinoma].

Serum alpha-L-fucosidase (AFU) was determined in 33 patients with hepatocellular carcinoma (HCC), 4 with secondary metastatic liver cancer, 61 with various liver diseases, 12 with gastrointestinal tumor and 50 healthy controls. The results showed that AFU level was significantly higher in HCC (14.48 +/- 5.77) than that in the controls (3.33 +/- 0.72) and in patient with other diseases (P less than 0.01). Serum AFU level was also increased in fulminant hepatitis (8.96 +/- 3.99), acute hepatitis (8.94 +/- 4.94) and chronic hepatitis (7.27 +/- 2.58), P less than 0.01 or 0.05. There was no significant difference in AFU level between the controls and patients with secondary metastatic liver cancer (6.25 +/- 0.84), cirrhosis (6.30 +/- 3.17), gastrointestinal tumor (4.43 +/- 1.64), liver hemangioma and liver abscess (4.86 +/- 2.22). A level exceeding 10.5u was a useful marker for the diagnosis of HCC with 78.8% sensitivity and 90.0% specificity. The diagnostic positivity was 81.8% in low AFP producing HCC, whereas 93.9% in those with elevated AFP. Our data indicate that serum AFU is a useful tumor marker for HCC, particularly in detection of AFP-low or negative HCC patients.

Adult↗
PubMed1987

A rat uterine horn model of genital tract wound healing.

A rat uterine horn model of genital tract wound healing is described. Healing was reflected by acquisition of strength and elasticity, measured by burst strength (BS) and extensibility (EX), respectively. A tensiometer (Instron Corp., Canton, MA) was used to assess these characteristics in castrated and estrogen-supplemented or nonsupplemented animals. While the horn weights (HW), BS, and EX of contralateral horns were not significantly different, the intra-animal variation of HW was 7.2%, BS was 17.7% and EX was 38.2%. In a second experiment, one uterine horn was divided and anastomosed, and the animal given estrogen supplementation or a placebo pellet. Estrogen administration was found to increase BS and EX of anastomosed horns prior to 14 days, but had no beneficial effect at 21 or 42 days. The data suggest that estrogen may be required for optimal early healing of genital tract wounds.

Animals↗
PubMed1987

Cryotherapy for the treatment of proximal urethral condyloma acuminatum.

Between March and November 1985 we treated 89 female patients with condyloma acuminatum of the lower genital tract. All patients were evaluated with colposcopy, urethroscopy and anoscopy. Carbon dioxide laser vaporization was used to treat condylomata in the cervix, vagina, vulva, anus and distal urethra. Urethral involvement by condylomata was found in 31 patients (35 per cent). Eight patients had biopsy proved proximal urethral condylomata (9 per cent). Cryotherapy was used to treat these lesions. Six patients required only 1 treatment, while 2 required 2 treatments to cure the proximal urethral condylomata.

Adult↗
PubMed1984

Vaccination of bovines against schistosomiasis japonica with highly irradiated schistosomula in China.

Vaccination of Chinese bovines (cattle and buffaloes) against schistosomiasis japonica with 36 kR gamma-irradiated schistosomula was done for laboratory challenge and for field trials in China. Altogether, 61 bovines were used. All experimental animals were vaccinated 2-3 times with 10,000 irradiated schistosomula per time. For the laboratory challenge, all experimental and control cattle were challenged with 500 normal cercariae and each buffalo, with 2,000 cercariae. The laboratory-challenged bovines were killed after 54-57 days of challenge; the bovines for the field trial in the lightly endemic area, after 5 months in the field; and the bovines for the field trial in the heavily endemic area, after 58-63 days. When the animals were killed, the number of mature worms in the vaccinated (experimental) and non-vaccinated (control) animals was recorded and the percentage of worm reduction in each group was calculated. The first group, consisting of three vaccinated and three non-vaccinated cattle, was given a laboratory challenge; the worm reduction was 71.6%. The second group, consisting of two vaccinated and three non-vaccinated buffaloes, was also given a laboratory challenge; the worm reduction was 74.4%. The third group, consisting of seven vaccinated and eight non-vaccinated buffaloes, was utilized in a field trial in a lightly endemic area; the worm reduction was 75.6%. The fourth group, consisting of eight vaccinated and nine non-vaccinated cattle, and the fifth group, consisting of nine vaccinated and nine non-vaccinated buffaloes, were pastured in a heavily endemic area. The worm reduction was 65.1% in the fourth group and 75.7% in the fifth group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Innovations in bayes and empirical bayes methods: estimating parameters, populations and ranks.

By formalizing the relation among components and 'borrowing information' among them, Bayes and empirical Bayes methods can produce more valid, efficient and informative statistical evaluations than those based on traditional methods. In addition, Bayesian structuring of complicated models and goals guides development of appropriate statistical approaches and generates summaries which properly account for sampling and modelling uncertainty. Computing innovations enable implementation of complex and relevant models, thereby substantially increasing the role of Bayes/empirical Bayes methods in important statistical assessments. Policy-relevant statistical assessments involve synthesis of information from a set of related components such as medical clinics, geographic regions or research studies. Typical assessments include inference for individual parameters, synthesis over the collection of components (for example, the parameter histogram) and comparisons among parameters (for example, ranks). The relative importance of these goals depends on the context. Bayesian structuring provides a guide to valid inference. For example, while posterior means are the 'obvious' and optimal estimates for individual components under squared error loss, their empirical distribution function (EDF) is underdispersed and never valid for estimating the EDF of the true, underlying parameters. Effective histogram estimates result from optimizing a loss function based in a distance between the histogram and its estimate. Similarly, ranking observed data usually produces poor estimates and ranking posterior means can be inappropriate. Effective estimates should be based on a loss function that caters directly to ranks. Using examples of 'borrowing information', shrinkage and the variance/bias trade-off we motivate Bayes and empirical Bayes analysis. Then, we outline the formal approach and discuss 'triple-goal' estimates with values that when ranked produce optimal ranks, for which the EDF is an optimal estimate of the parameter EDF and such that the values themselves are effective estimates of co-ordinate-specific parameters. We use basic models and data analysis examples to highlight the conceptual and structural issues.

Animals↗
PubMedDate not supplied

Triple-goal estimates for disease mapping.

Maps of regional morbidity and mortality rates play an important role in assessing environmental equity. They provide effective tools for identifying areas with potentially elevated risk, determining spatial trend, and formulating and validating aetiological hypotheses about disease. Bayes and empirical Bayes methods produce stable small-area rate estimates that retain geographic and demographic resolution. The beauty of the Bayesian approach lies in its ability to structure complicated models, inferential goals and analyses. Three inferential goals are relevant to disease mapping and risk assessment: (i) computing accurate estimates of disease rates in small geographic areas; (ii) estimating the distribution of disease rates over the region; (iii) ranking the disease rates so that environmental investigation can be prioritized. No single set of estimates can simultaneously optimize these three goals, and Shen and Louis propose a set of estimates that perform well on all three goals. These are optimal for estimating the distribution of rates and for ranking, and maintain a high accuracy in estimating area-specific rates. However, the Shen/Louis method is sensitive to choice of priors. To address this issue we introduce a robustified version of the method based on a smoothed non-parametric estimate of the prior. We evaluate the performance of this method through a simulation study, and illustrate it using a data set of county-specific lung cancer rates in Ohio.

Algorithms↗
PubMedDate not supplied

Contribution of the ventricles and the atrial appendages to the elevation of plasma atrial natriuretic factor (ANF) during pacing-induced heart failure in conscious dogs.

The goal of our study was to determine whether the elevation in plasma ANF was produced by the atrial appendages or ventricular tissue during pacing-induced heart failure in chronically instrumented conscious dogs (sham) or dogs with bilateral atrial appendectomy. Acute volume expansion caused a significant elevation of plasma ANF from 80 +/- 8 to 149 +/- 26 pg/ml (p < 0.01) in sham dogs, but caused no significant change from 67 +/- 7 to 84 +/- 8 pg/ml in atrial appendectomized dogs. There were increases in left ventricular end-diastolic pressure (LVEDP) and left atrial pressure (LAP) in both groups of dogs. After rapid left ventricular pacing (210-240 beats/min) for 4 weeks to induce heart failure, dogs in both groups had tachycardia, elevated LVEDP and higher LAP. Plasma ANF was increased by 250% to 283 +/- 64 pg/ml (p < 0.01) in sham dogs, and only 40% to 94 +/- 15 pg/ml (p > 0.05) in atrial appendectomized dogs. In response to volume expansion, there were further increases in LVEDP and LAP in both groups of dogs, but plasma ANF was not elevated (288 +/- 39 pg/ml) in sham dogs and only slightly increased (132 +/- 7 pg/ml) in atrial appendectomized dogs. Our results suggest that, during pacing-induced heart failure, the atrial appendages are the major source of elevated plasma ANF, and the remaining atrial and ventricular tissue, even when maximally stretched, can only modestly increase plasma ANF.

Animals↗