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W Powers

Publications and source records attributed to W Powers.

12 recordsLinked to original sources
PubMed2006

Effect of dietary phosphorus, phytase, and 25-hydroxycholecalciferol on broiler chicken bone mineralization, litter phosphorus, and processing yields.

Three floor pen experiments (Exp) were conducted to evaluate low nonphytin P (NPP) concentrations and the NPP sparing effect of phytase (PHY) and 25-hydroxycholecalciferol (25D) on bone mineralization, bone breaking during commercial processing, litter P, and water-soluble P (WSP) concentrations. Tested treatments (TRT) were control, National Research Council NPP; University of Maryland (UMD) NPP; UMD + PHY, UMD NPP reduced by 0.064% NPP + 600 U of PHY/kg; UMD + PHY + 25D, UMD NPP reduced by 0.090% NPP + 600 U of PHY and 70 microg of 25D/kg; control + PHY mimicked the industry practice of diets by 0.1% when PHY is added; and negative control with 90% UMD NPP concentrations. UMD + PHY and control + PHY diets contained 600 U of PHY/kg, and UMD + PHY + 25D contained 600 U of PHY + 70 microg of 25D/kg. Performance results were presented separately. After each Exp, litter P and WSP were determined, and bone measurements were obtained on 8 or 10 broilers per pen. Tested TRT did not affect broiler BW. Femur ash weight of broilers fed the UMD and UMD + PHY + 25D was lower in all Exp compared with that of broilers fed the control diet. Femur ash was similar for control and UMD + PHY broilers, yet averaged over all Exp, UMD + PHY broilers consumed 39% less NPP and required less NPP per gram of femur ash than those on the control (4.87 and 7.77 g of NPP/g of ash, Exp 3). At the end of Exp 3, broilers were processed in a commercial facility. Despite reductions in NPP intake and bone mineralization, no differences were observed in measurements of economic importance (parts lost, carcass yield, and incidence of broken bones). The P excretion per bird was lowest for birds fed the UMD + PHY + 25D diet followed by those fed the UMD + PHY and negative control diets (10.44, 12.00, and 13.78 g of P/bird, respectively) and were highest for those fed the control diet (19.55 g of P/bird). These results suggest that feeding diets low in P together with PHY and 25D will not affect performance or increase losses at processing while resulting in improved P retention and reductions in P and WSP excreted.

6-Phytase↗
PubMed2005

The role of radiotracer imaging in Parkinson disease.

Radiotracer imaging (RTI) of the nigrostriatal dopaminergic system is a widely used but controversial biomarker in Parkinson disease (PD). Here the authors review the concepts of biomarker development and the evidence to support the use of four radiotracers as biomarkers in PD: [18F]fluorodopa PET, (+)-[11C]dihydrotetrabenazine PET, [123I]beta-CIT SPECT, and [18F]fluorodeoxyglucose PET. Biomarkers used to study disease biology and facilitate drug discovery and early human trials rely on evidence that they are measuring relevant biologic processes. The four tracers fulfill this criterion, although they do not measure the number or density of dopaminergic neurons. Biomarkers used as diagnostic tests, prognostic tools, or surrogate endpoints must not only have biologic relevance but also a strong linkage to the clinical outcome of interest. No radiotracers fulfill these criteria, and current evidence does not support the use of imaging as a diagnostic tool in clinical practice or as a surrogate endpoint in clinical trials. Mechanistic information added by RTI to clinical trials may be difficult to interpret because of uncertainty about the interaction between the interventions and the tracer.

Biomarkers↗
PubMed2005

Effects of dietary phosphorus, phytase, and 25-hydroxycholecalciferol on performance of broiler chickens grown in floor pens.

Three 49-d experiments (Exp 1, 2, and 3) with broilers in floor pens were conducted to test the applicability of nonphytin phosphorus (NPP) requirements and the NPP-sparing effect of phytase (PHY) and 25-hydroxycholecalciferol (25D) determined previously in battery Exp. Six dietary NPP treatments were tested using a 4-phase feeding program. Treatments 1 to 6 were NRC (1994) NPP (C); University of Maryland (UMD) NPP; UMD NPP - 0.064% (UMD+PHY); UMD NPP - 0.09% (UMD+PHY+25D); NRC - 0.10% (C+PHY), and 90% UMD NPP (NC), respectively. Treatments 3, 4, and 5 had 600 U of PHY/kg of diet. Treatment 4 also had 70 microg of 25D/kg of diet; NPP concentrations were reduced to account for the sparing effect of these additives. No differences in hatch to 49 d BW were observed between treatments in Exp 1 and 2, and only in Exp 3 were the BW of the NC broilers (2.86 kg) different (P < 0.05) from those fed the C, UMD, and UMD+PHY treatments (2.96, 2.94, and 2.98 kg, respectively). Cumulative NPP consumption per bird was lowest (P < 0.05) for broilers fed the UMD+PHY+25D treatment (8.65 g in Exp 3) compared with those fed the C, NC, UMD, and UMD+PHY treatments (18.19, 10.60, 13.63, and 11.01 g, respectively for Exp 3). Application of any of these treatments reduced total P and NPP consumption compared with C. The results of this series of floor pen Exp validate the UMD NPP recommendations for a 4-phase feed program and the PHY and 25D NPP-sparing effects observed in battery trials without negatively affecting broiler performance.

6-Phytase↗
PubMed1998

A slant on cloning.

Human cloning may be the most difficult moral dilemma posed by science since splitting of the atom. But recent stories in The New York Times suggest the ethical debate is all but over. Now, along comes Dr. Seed.

Cloning, Organism↗
PubMed1996

Gastric adenocarcinoma in patients 40 years of age or younger.

BACKGROUND: Gastric adenocarcinoma is considered a disease of the middle aged and elderly and has been infrequently reported in patients under 40 years of age. The purpose of this study was to determine the proportion of young patients diagnosed with gastric adenocarcinoma and to compare the demographic, clinical and pathologic features of younger and older patients with gastric adenocarcinoma. METHODS: A retrospective cohort study using tumor registry records of all patients with gastric adenocarcinoma diagnosed from 1982 through 1996 at a public teaching hospital. Demographic, clinical, and pathologic comparisons were made between patients younger than 41 years of age and race- and sex-matched older patients with gastric adenocarcinoma. RESULTS: Thirty of 203 (15%) cases of gastric adenocarcinoma were diagnosed in patients less than 41 years (range 23 to 40). Male to female ratio was 1:1. Young patients were more likely to be black (33% versus 17%, P = 0.04) Both younger and older patients presented with advanced disease, with nearly half of each group having metastases. Twelve of 29 (41%) younger patients were operated on without a histologic diagnosis of gastric adenocarcinoma in contrast to only 1 older patient (P < 0.001). One of 30 (3%) young patients is alive 39 months following gastrectomy. Twenty patients died and the remaining 9 were lost to follow-up, all with known residual or recurrent disease. Six-month survival of young patients (23%) was less than older patients (42%) (P = 0.14). Young patients were more likely to have diffuse histology (80% versus 55%, P = 0.12). Overt infection with Helicobacter pylori was uncommon in both groups. CONCLUSIONS: Young patients accounted for an unusually high proportion of patients with gastric adenocarcinoma diagnosed at our public teaching hospital. Young patients were significantly more likely to be black and less likely to have an accurate preoperative histologic diagnosis. Both young and older patients presented with advanced disease and had poor survival. Young patients were more likely to have diffuse histology and had poorer 6-month survival, suggesting a more aggressive variety of the disease in this group.

Adenocarcinoma↗
PubMed1991

Electron microscopic characterization of neonatal platelet ultrastructure: effects of sampling techniques.

Detailed ultrastructure of 720 neonatal platelets was systematically examined in 200-300 microliters cord blood samples from four normal term infants. There were no differences in platelet organelles between samples collected into standard sodium citrate anticoagulant and minimally heparinized samples collected into sodium citrate. Samples collected into EDTA showed significant differences from the other two solutions. There were also differences in organelle characteristics within a solution group, as time from sample collection to EM fixation varied. These results verify utilization of small minimally heparinized blood samples for examination of platelet ultrastructure. This system can now be expanded to the premature infant, where small blood sample requirements are essential, and minimally heparinized blood may be more readily available.

Anticoagulants↗
PubMed1988

Administration of indomethacin for the prevention of periventricular-intraventricular hemorrhage in high-risk neonates.

One hundred twenty-two preterm infants were enrolled in a placebo-controlled, double-blind trial using intravenous indomethacin for the prevention of periventricular-intraventricular hemorrhage (PVH-IVH). Before random assignment, data on the infants were stratified according to low-weight (500 to 999 g) or high-weight (1000 to 1500 g) subgroups. Cranial sonography was used to document the absence of PVH-IVH before enrollment and the occurrence of PVH-IVH during the 7-day protocol. Indomethacin, 0.1 mg/kg, or placebo was administered before 12 hours of age and at 24, 48, and 72 hours of age. Five patients receiving indomethacin and six receiving placebo were withdrawn before completion of the study. In the remaining 111 patients, the indomethacin and placebo groups were comparable with respect to gestational ages, maternal complications, Apgar scores, ventilatory requirements, complications of prematurity, and mortality rate. PVH-IVH developed in six of 56 infants who received indomethacin and 11 of 55 infants who received placebo (P = 0.174). Analysis of the individual strata showed that the indomethacin-treated infants in the low-weight subgroup sustained a higher mortality rate (11/17 vs 3/16; P = 0.008) without a reduction in the incidence of PVH-IVH. Infants in the indomethacin-treated high-weight subgroup demonstrated a significantly lower incidence of PVH-IVH (2/39 vs 8/39; P = 0.04), but the frequency of high-grade hemorrhages was comparable for both indomethacin- and placebo-treated groups. In summary, the prophylactic administration of intravenous indomethacin for the prevention of PVH-IVH cannot be recommended for infants less than 1000 g. In preterm infants between 1000 and 1500 g birth weight, indomethacin significantly reduced the incidence of PVH-IVH.

Birth Weight↗
PubMed1988

Polyethylene-lead tissue compensators for megavoltage radiotherapy.

Tissue compensators afford one the opportunity of producing idealized dose distributions in radiotherapy. We have developed a technique which may be used to produce fast, accurate and inexpensive compensators within a few minutes and requires minimal patient involvement. Three dimensional contour data is acquired using a moire fringe photograph taken at the time of simulation. The photograph is projected to the size needed for the actual compensator and a sketch of the compensator is made. The sketch is placed in a specially designed small portable pantographic unit and the design is traced while the unit cuts the compensator from an indexed polyethylene-lead blank which is premounted on an acrylic tray. The polyethylene-lead material proves to have an ideal combination of properties for compensator construction including relatively high density, ease of machining, good handling characteristics and low cost.

Humans↗
PubMed1980

Combined modality therapy for advanced head and neck cancer.

Seventy-five patients with stage III and IV squamous cell cancer of the head and neck, previously untreated, had two courses of chemotherapy with cis-platinum, Oncovin and bleomycin, followed by radical surgery, radiotherapy or both. Response to chemotherapy (complete and partial) was high (80 percent). In 36 patients radical surgery became possible. The overall survival improved statistically in patients who achieved complete or partial response to chemotherapy compared with those who had minimal or no response. Patients with well to moderately well differentiated cancer, or stage III disease, had a statistically better prognosis than patients with poorly differentiated cancer, or stage IV disease.

Bleomycin↗
PubMed1978

Are there two logistic regressions for retrospective studies?

A comparison is made between two different approaches to the linear logistic regression analysis of retrospective study data: the prospective model wherein the dependent variable is a dichotomous indicator of case/control status; and the retrospective model wherein the dependent variable is a binary or polychotomous classification of exposure. The two models yield increasingly similar estimates of the relative risk with increasing degrees of covariate adjustment. When the covariate effects are saturated with parameters, the relative risk estimates are identical. The prospective model is generally to be preferred for studies involving multiple quantitative risk factors.

Child↗