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Biomedical subjects

C Wyatt

Publications and source records attributed to C Wyatt.

At least 19 recordsLinked to original sources
PubMed2006

Safety of low-dose radiocontrast for interventional AV fistula salvage in stage 4 chronic kidney disease patients.

The Dialysis Outcomes Quality Initiative emphasizes increasing arteriovenous fistula prevalence, by promoting referral for fistula creation in patients with stage 4 chronic kidney disease (CKD). The aim is to provide an optimal access for initiation of dialysis, thus avoiding central venous catheter use. The endovascular management of nonmaturing fistulas is more complicated in these patients, where the expected benefit of catheter avoidance must be weighed against the risk of contrast induced nephropathy (CIN). This study reports on the safety of a low-dose radiocontrast regimen, used in performing endovascular fistula salvage procedures in patients with stage 4 CKD. All consecutive endovascular procedures performed over a 2-year period in patients with stage 4 CKD and nonmaturing access were identified. Data collected included the type of procedure, contrast volume per procedure, pre, 2- and 7-day creatinine, need for acute dialysis, and the type of access used to initiate dialysis. Total of 65 procedures were performed in 34 patients. The mean contrast volume was 7.8 ml per procedure. The incidence of CIN (25% increase in serum creatinine) was 4% at 2 days and 4.6% at 1 week. All values returned to baseline within 2 weeks, and no patient required acute dialysis. Among the 33 patients with nonmaturing fistulas, 20 initiated dialysis during the follow-up period, 15 (75%) using their fistula, and five (25%) using a catheter. This study demonstrates that in patients with advanced CKD, fistulas can be successfully salvaged using small contrast volumes with a low incidence of CIN.

Aged↗
PubMed2003

Methionine and cystine requirements of slow- and fast-feathering male broilers from zero to three weeks of age.

Two experiments were conducted with fast- (Ross x 3F8) and slow- (Ross x 308) feathering broiler males from 0 to 3 wk of age to determine Met and Cys requirements. A corn-soybean meal basal diet was formulated to be deficient in Met and Cys but was adequate in all other nutrients (22.0% CP; 3,050 kcal ME/kg). In experiment 1, diets contained 0.50% dietary Cys with 0.35, 0.40, 0.45, and 0.50% total Met. Feed conversion (FC) of slow- and fast-feathering males improved in a similar manner to 0.50% Met (linear, P < 0.05). Nitrogen retention measured from 20 to 21 d of age optimized at 0.46% Met (quadratic, P < 0.01), regardless of feathering rate. Experiment 2 examined the response to feeding 0.35, 0.40, 0.45, and 0.50% total Cys in diets having total Met at 0.45%. Increasing Cys improved FC that optimized at 0.40% with fast-feathering birds (quadratic, P < 0.01), whereas slow-feathering broilers were not responsive. Nitrogen retention measured from d 20 to 21 did not indicate a difference attributable to feathering but a Cys optimization at 0.43% with both broiler sources. Present experimentation indicates a Met requirement approximating 0.50% is appropriate for broilers 0 to 3 wk of age, regardless of feather rate; however, the estimated Cys requirement for slow-feathering males (0.39%) was less than for fast-feathering (0.44%) males.

Animal Feed↗
PubMed1999

The effect of dietary wheat middlings and enzyme supplementation II: apparent nutrient digestibility, digestive tract size, gut viscosity, and gut morphology in two strains of leghorn hens.

An experiment was conducted with two strains of Leghorn hens, DeKalb Delta (D) and Hisex White (H), to investigate the effect of a commercial poultry enzyme preparation (EZ; xylanase plus protease) on the digestibility of protein, fat, Ca, and P and to determine any changes in the relative size of the digestive tract, gut morphology, and gut viscosity (GV) of birds fed wheat middlings (WM) over an 18-wk period. Three hundred birds (150 birds per strain) were randomly assigned to six diets: Diet 1, control (corn-soybean); Diets 2 and 3, 8% and 16% WM, respectively; Diet 4, 8% WM and 0.1% enzyme (EZ); and Diets 5 and 6, 16% WM and 0.1% and 0.2% EZ, respectively. There were five replicates per diet per strain. At 50 wk, protein digestibility increased significantly with supplementation of EZ, but, at 60 wk, all responses were similar. Protein digestibility was greater in DeKalb Deltas for WM with EZ compared with Hisex on the same treatment. Fat digestibility was greater for Diet 1 than the other diets at 50 wk but showed a similar response at 60 wk. The H strain showed a reduction in fat digestibility with WM diets with EZ. The control diet showed greater Ca digestibility than the other diets at 50 wk but did not differ at 60 wk. Phosphorus digestibility increased significantly for WM diets with or without EZ at 60 wk. Intestinal weight was significantly higher for WM with or without EZ at 50 wk, but was equal to the control diet at 60 wk. At 60 wk, gizzard weights (GW) were also lower in birds fed WM and WM with EZ compared with birds fed the control, but GV was not affected by dietary treatments. Histological observations on jejunum of birds fed WM without EZ showed shortening, thickening, and atrophy of the villi, all of which improved when EZ was included in the diet. Availability of some nutrients in WM diets was improved with supplementation of enzyme. Gastrointestinal (GI) tract and organ size were increased, and gut morphology appeared to be improved.

Animals↗
PubMed1999

The effect of dietary wheat middlings and enzyme supplementation. 1. Late egg production efficiency, egg yields, and egg composition in two strains of Leghorn hens.

A study was conducted to test the effects of wheat middlings (WM) with and without enzyme (xylanase and protease) supplementation on late egg production (EP), egg yields, and egg composition in two strains of Leghorn hens (DeKalb Delta and Hisex White). Six diets were randomly assigned to 300 birds (150 birds per strain) from 42 to 60 wk of age. Diet 1 was a corn-soybean meal control, Diets 2 and 3 had 8 and 16% WM, respectively, Diet 4 had 8% WM with 0.1% enzyme, and Diets 5 and 6 had 16% WM with 0.1 and 0.2% enzyme, respectively. Each dietary treatment was replicated five times per strain. Egg production, feed consumption (FC), feed efficiency (FE), percentage dirty eggs, specific gravity (SP), egg weight (EW), and egg mass (EM) were measured on a weekly basis. Egg components (EC) were measured biweekly and birds were weighed every 4 wk. Egg production was not significantly affected by diet, with averages of 83.7, 85.7, 84.1, 84.2, 82.3, and 84.0% for Diets, 1, 2, 3, 4, 5, and 6, respectively. Strain had a marked effect on FC, with Hisex having higher FC than DeKalb hens. Feed consumption also showed a significant diet by strain effect, being lower for Hisex hens fed diets with enzyme compared to diets without enzyme. DeKalb hens had better FE than Hisex hens, and addition of enzyme to 16% WM improved it further. Strain and diet had a significant effect on EC with higher percentages of albumen and yolk for diets with enzyme and for DeKalb hens. Percentage shell was lower for DeKalb hens than for Hisex hens but was not affected by diet. There was also a significant increase in EW for Diets 4 (63.1 g), 5 (63.8 g), and 6 (63.2 g) compared to Diets 1 (62.1 g), 2 (62.4 g), and 3 (63.0 g), with DeKalb hens showing an increase with Diet 5 compared to Hisex hens. Egg mass improved with the higher rate of enzyme in 16% WM diet compared to the lower enzyme level. Specific gravity declined with enzyme supplementation in WM diets. Eggs from DeKalb hens had lower SP than those from Hisex hens for all diets. Percentage dirty eggs did not differ significantly among treatments but was higher for the Hisex strain than for the DeKalb strain. There were no differences in BW between the two strains of hens or among diets. Adding protease and xylanase to diets rich in fiber can improve the egg output without affecting production parameters.

Animal Husbandry↗
PubMed1998

High titers of antibodies inhibiting the binding of envelope to human cells correlate with natural resolution of chronic hepatitis C.

Most cases of hepatitis C virus (HCV) infection result in chronic disease; however, a very small fraction of patients naturally clear the virus and resolve chronic hepatitis. In an attempt to correlate immune response with chronic disease resolution, we compared the antibody response in patients with different outcomes of the infection. Antibody responses to HCV structural proteins were assessed in 34 patients originally diagnosed with acute hepatitis. Five cases resolved acute infection, 22 developed chronic hepatitis, and 7 naturally resolved chronic hepatitis C. To estimate HCV neutralizing antibodies we used the neutralization of binding (NOB) assay, which evaluates inhibition of the envelope-2 protein binding to human cells. Enzyme-linked immunosorbent assay was used for the quantitative assessment of serum antibodies. The presence of HCV RNA was ascertained by reverse transcription-polymerase chain reaction. In 6 of 7 patients naturally recovered from chronic hepatitis C, the emergence and the persistence (for more than 3 months) of high serum titers (>1/600) of NOB antibodies coincided with virus clearance and clinical resolution of hepatitis. NOB antibody activity was observed in only 2 of 5 patients recovered from acute hepatitis C. Chronic patients who did not show any resolution during the course of the study developed low or no NOB antibodies. Because of the correlation between prolonged high NOB titers and natural resolution of chronic hepatitis C, vaccination or passive immunization aimed at high titers of NOB antibodies may be valuable new therapeutic approaches for chronic hepatitis C.

Adult↗
PubMed1996

Antitumour activity of S-p-bromobenzylglutathione cyclopentyl diester in vitro and in vivo. Inhibition of glyoxalase I and induction of apoptosis.

The glyoxalase I inhibitor diester, S-p-bromobenzyl-glutathione cyclopentyl diester (BrBzGSHCp2), inhibited the growth of human leukaemia 60 (HL60) cells in vitro. The median growth inhibitory concentration GC50 value of BrBzGSHCp2 was 4.23 +/- 0.001 microM (n = 21), and the median toxic concentration TC50 value was 8.86 +/- 0.01 microM (n = 21). BrBzGSHCp2 inhibited DNA synthesis in the third hr of incubation: the median inhibitory concentration IC50 value was 6.11 +/- 0.02 microM (n = 8). Incubation of HL60 cells with 10 microM BrBzGSHCp2 delivered the diester into cells: de-esterification of the diester there in lead to formation of the S-p-bromobenzylglutathione, inhibition of glyoxalase I activity in situ, increase in the methylglyoxal concentration after 1 hr, and induction of apoptosis after 6 hr. BrBzGSHCp2 (50-200 mg/kg) also inhibited the growth of murine adenocarcinoma 15A in vivo. Glyoxalase I inhibitor diesters may, therefore, inhibit tumour growth by inducing the accumulation of methylglyoxal in tumour cells, and induction of apoptosis.

Adenocarcinoma↗
PubMed1995

Directionally selective motion detection in the sustaining fibers of the crayfish optic nerve: linear and nonlinear mechanisms.

1. Directional selectivity of crayfish sustaining fibers was examined with drifting sine wave gratings and with intracellular and extracellular recordings. Directionality was measured for variations in stimulus contrast, spatial frequency, and temporal frequency. 2. Sustaining fibers exhibit directional selectivity in the magnitude of the compound postsynaptic potential (PSP), the impulse frequency modulation response, and the mean firing rate. The mean synaptic potential is insensitive to direction. The directionality of the mean impulse rate appears to arise by rectification in the voltage-to-impulse transduction. 3. The preferred directions of three identified sustaining fibers are similar to those of head-down optomotor neurons to which these sustaining fibers project. 4. The modulatory response, elicited by gratings drifting in the preferred direction, increased linearly with contrast until saturation (typically at a contrast of 0.5), where maximum directional selectivity obtains. 5. The magnitude of the directional response is a band-pass function of spatial and temporal frequency and exhibits reversal of directionality (i.e., aliasing) at high spatial and temporal frequencies. The results imply a spatial sampling interval of 4.5 degrees and a temperature-dependent inhibitory delay of 40-90 ms. The PSP modulation response shares several features with that of neighboring tangential (Tan1) neurons. 6. A qualitative model is proposed for the transformation of a phase-sensitive, linear directional response to a phase-insensitive and nonlinear time-averaged response, based on the functional connections from Tan1 neurons to sustaining fibers to optomotor neurons. The model includes a threshold rectification, a synaptic band-pass filter, and differences in temporal phase among converging modulatory signals.

Animals↗
PubMed1994

Getting rid of paper pushing.

A hospital in Tacoma, Wash., is taking several steps toward streamlining its business office functions. For example, the hospital is transmitting 90% of its claims electronically and has automated the posting of remittance advice and the billing of Medicare secondary payers. "Eventually we'll have a paperless system; we won't push paper back and forth," the hospital's patient accounts manager says.

Catholicism↗
PubMed1991

Spironolactone causes a rapid down regulation of sigma recognition sites in guinea pig brain and liver.

The effect of dosing guinea pigs with spironolactone (100 mg/kg twice daily for 3 days) upon the sigma recognition site labelled with [3H]-DTG was investigated. Animals were dosed with 100 mg/kg spironolactone twice a day for 3 days. Spironolactone treatment caused a decrease in sigma radioligand binding in membranes prepared from liver and brain but not in adrenals or testes. Saturation analysis of [3H]-DTG radioligand binding in the brain indicated that the decrease in specifically bound [3H]-DTG binding was due to a reduction in receptor number with no change in affinity. This method for the selective depletion of brain and liver sigma recognition sites will provide a useful tool for exploring the functional significance of this site.

Adrenal Glands↗
PubMed1986

Patterns of blood supply to the gastric mucosa. A comparative study revealing an end-artery model.

The form of the gastric arterial supply to the mucosa has been studied in dog, swine, ferret, cat, guinea-pig, rabbit and rhesus monkey. In all these species, the bore of vessels in the submucous plexus diminished from body to pylorus, though this was most marked in the guinea-pig and rabbit. The plexus was also continuous across the pylorus with duodenal vessels. Thus the well known poverty of vascularity in distal parts of the human stomach is shared by other species and is unlikely to be a contributory factor to the initiation of peptic ulcer, a disease limited to man. In dog, swine, ferret and cat, as in man, the primary (largest) and secondary (smaller) components of the plexus lay entirely in the submucosa. In the cat, there was a secondary plexus of much smaller vessels deep to the muscularis mucosae. In the guinea-pig, rat, rabbit and monkey, both plexuses were mostly embedded within the muscularis mucosae. As a result, mucosal arteries had two modes of origin: (a) the first, in which they did not pass through the muscularis mucosae as exemplified in the cat, and (b) the second, where they did pass through muscularis mucosae as exemplified by the dog, ferret and swine; in other species, they passed through part of the muscularis mucosae. Areas of mucosa supplied by a single mucosal artery were measured, and ranged widely from the smallest in the cat to the largest in the dog. These features do not seem to have been reported previously, and may be associated with as yet undiscovered functional mechanisms of the muscularis mucosae. Mucosal arteries of extramural origin were found to occur occasionally in the guinea-pig and rabbit, and hence these may provide an experimental model of the pattern existing in man.

Animals↗