Biomedical subjects

H R Wilson

Publications and source records attributed to H R Wilson.

At least 91 records · Page 5Linked to original sources

PubMed1991

Comparison of energy utilization efficiency among six lines of White Leghorns.

Individual records were used of feed consumption, BW, BW change, and egg mass (EM) output during a 4-wk period for 180 hens from six different lines of White Leghorn chickens (30 hens per line). The diet contained 16.45% protein and 2,825 kcal ME/kg. Feed consumption was used to calculate actual ME intake (AcME) for each hen. Multiple regression of AcME was performed with metabolic BW, BW change, and EM production as independent variables. The regression coefficients and the independent variables were then used to calculate the expected ME intake (ExME). The following values were calculated for each hen and were used to compare energy efficiency among the six lines: the residual component of energy intake (RES), defined as the difference between the AcME intake and ExME intake; the relative efficiency ratio (RER), defined as (ExME divided by AcME) X 100 (calculated using the partial regression coefficients of the overall equation); and feed conversion, the ratio of feed consumed to EM. Significant differences among the lines in efficiency of EM produced were observed regardless of the efficiency measurement used. Feed consumption did not indicate differences in RES or RER. A multiple regression equation was derived for each line. Significant differences were found among the six lines in their energy requirements for maintenance and for egg production. These results suggest the possible use of the partial regression coefficients as selection criteria for separately improving maintenance efficiency and egg production efficiency.

Analysis of Variance↗

PubMed1991

Effect of time of feeding on oviposition time and production parameters in broiler breeders.

In Experiment 1, four pens of 90 Ross dwarf broiler breeder hens and 9 cocks each were assigned to feeding times of 0830, 1130, and 1430 h. Eggs were collected hourly from 0800 to 1600 h, 5 days/wk for 4 wk. In Experiment 2, five pens of 30 Arbor Acres and 3 cocks each were assigned to feeding times of 0830, 1130, 1430, and 1730 h. Eggs were collected hourly from 0700 to 1600 for Days 6 through 10 of a 10-day treatment period. Feeding time did not significantly change oviposition time in dwarf broiler breeders, except for an increase in oviposition at 1600 h for hens fed at 1130 and 1430 h. Peak oviposition times were 1000 and 1100 h with distribution of ovipositions throughout the day. Egg weight, shell thickness, and egg production were not significantly affected by feeding time. In the standard-sized strain, afternoon feeding times significantly increased the proportion of afternoon ovipositions. The incidence of floor, dirty, cracked, and abnormal eggs was not significantly changed by feeding time in either experiment.

Analysis of Variance↗

PubMed1991

Research note: Feeding various levels of ground Sesbania macrocarpa Muhl. seed to bobwhite quail.

Two 28-day experiments were conducted to determine the effects of various levels of ground Sesbania macrocarpa Muhl. seed on mature bobwhite quail. In Experiment 1, S. macrocarpa Muhl. seed levels of 0, 1, 2, 3, 4, and 5% were added to a basal diet at the expense of filler and fed to five replicate groups of six 58-wk-old paired quail (one male and one female). Average daily feed consumption, hen-day egg production, average BW change, mortality, fertility, and hatchability were monitored. Four groups of eight individually caged females, 63 wk of age, were each given a diet containing 0, 2, 4, 6, 8 or 10% ground S. macrocarpa Muhl. seed in Experiment 2. A seventh treatment was added that consisted of 10% ground S. macrocarpa Muhl. from an older seed shipment used previously in work with White Leghorn hens. Increasing S. macrocarpa Muhl. seed levels in Experiment 1 did not cause significant deviations from the control treatment for average daily feed consumption, BW change, hen-day egg production, fertility, total hatchability, or hatchability of fertile eggs. In Experiment 2 neither average daily feed consumption nor hen-day egg production were affected by seed level or source. Quail given the 10% seed level using the older seed shipment had a significantly greater weight loss than the control birds. With the exception of this greater weight loss and in contrast with work involving chickens, dietary levels of ground S. macrocarpa Muhl. seed of up to 10% were acceptable to bobwhite quail.

Animal Feed↗

PubMed1991

Growth and performance of broiler breeders fed bacitracin methylene disalicylate and zinc bacitracin.

Day-old Cobb broiler breeder pullets were randomly allotted into 20 floor pens where they were brooded and reared to 23 wk of age. Eight pens received a control diet containing no growth promotant. The other 12 were fed 55 mg of bacitracin methylene disalicylate/kg of diet. Males were reared separately on the control diet. Pullets were full-fed for the first 8 wk of life, then placed on a skip-a-day program with breeder-recommended feed allocations. At 23 wk of age bird numbers were reduced to 26 females per pen, three males added, and diets changed to the layer regimen. Levels of 0, 27.5, 55, or 110 mg/kg of zinc bacitracin were each assigned to five pens with factorial attention to growing treatment. Layer treatments were continued for 280 days. No significant differences were associated with the feeding of bacitracin methylene disalicylate among body weight or mortality data summarized at 8 and 23 wk. Eight-week feed efficiency was also not affected. In the laying phase, 110 mg/kg of zinc bacitracin significantly improved egg production and fertility over the unsupplemented controls. Hatch of fertile eggs, overall hatchability, and the number of chicks per pen were all significantly improved by 27.5 mg/kg of zinc bacitracin. Higher drug levels supported no additional improvement. Feed efficiency, mortality rate, and final body weight were not significantly influenced by any level of supplementation. No effect of grower treatment upon subsequent layer performance was noted.

Animal Feed↗

PubMed1990

Perceived direction of moving two-dimensional patterns.

When two drifting cosine gratings are superimposed, they will, under appropriate conditions, form a coherently moving two-dimensional pattern whose resultant direction of motion may either be between (type I), or outside (type II) the directions of the two components. We have previously shown that type I patterns produce much stronger masking than either of their components, while type II patterns do not. In this study, we measured perceived direction of motion and thresholds for discrimination of motion direction. We found that type II patterns had a perceived bias of about 7.5 deg toward the direction of their components, and had discrimination thresholds around 6.5 deg, whereas type I patterns had discrimination thresholds around 1.0 deg and no significant bias. We conclude that the neural mechanisms which compute two-dimensional image motion do not strictly implement the intersection-of-constraints construction proposed by Adelson and Movshon (1982).

Discrimination, Psychological↗

PubMed1990

Effects of setting eggs small end up on hatchability and posthatching performance of broilers.

1. Hatchability of fertile eggs incubated with their small ends up (SEU) was 16 to 27% lower than for eggs set with their large ends up (LEU). In addition, the SEU position produced more nonviable chicks. 2. There were no differences in post-hatching performance between the two incubation treatments. 3. A survey in a commercial hatchery revealed that the frequencies of eggs set upside down by mistake varied from 0.3% to 3.4%. The setting of eggs upside down was attributed not to difficulties in distinguishing the large and small ends of the eggs but to human error. A decrease in the number of Grade-A chicks of about 0.2% was observed for every 1% of eggs set upside down, suggesting it may be of economic importance to ensure that the eggs are set properly with their large ends up.

Animals↗

PubMed1990

Role of the purine repressor in the regulation of pyrimidine gene expression in Escherichia coli K-12.

The pyrC and pyrD genes of Escherichia coli K-12 encode the pyrimidine biosynthetic enzymes dihydroorotase and dihydroorotate dehydrogenase, respectively. A highly conserved sequence in the promoter regions of these two genes is similar to the pur operator, which is the binding site for the purine repressor (PurR). In this study, we examined the role of PurR in the regulation of pyrC and pyrD expression. Our results show that pyrC and pyrD expression was repressed approximately twofold in cells grown in the presence of adenine [corrected] through a mechanism requiring PurR. A mutation, designated pyrCp926, which alters a 6-base-pair region within the conserved sequence in the pyrC promoter eliminated PurR-mediated repression of pyrC expression. This result indicates that PurR binds to the pyrC (and presumably to the pyrD) conserved sequence and inhibits transcriptional initiation. We also demonstrated that the pyrCp926 mutation had no effect on pyrimidine-mediated regulation of pyrC expression, indicating that pyrimidine and purine effectors act through independent mechanisms to control the expression of the pyrC and pyrD genes.

Amidohydrolases↗

PubMed1990

Do Gabor functions provide appropriate descriptions of visual cortical receptive fields?

Several recent theoretical models for human spatial vision posit that cortical receptive fields act to minimize simultaneously the product of the standard deviation of the sensitivities to position (delta chi) and to spatial frequency (delta omega) in accord with the uncertainty principle from Fourier analysis. The receptive-field functions resulting from this approach--one-dimensional or two-dimensional Gabor elementary functions--have been shown by others to fit measured receptive fields adequately in some species. However, only complex-valued Gabor functions minimize this product, and these cannot be fitted to single-cell receptive fields. We point out that the derivations of others have an implied metric or measure of positional and spatial-frequency uncertainties and that there is an infinitely large class of such metrics, many of which yield other receptive-field functions that are quite plausible biologically. We review neurophysiological measurements of others and analyze psychophysical masking data and find that in many cases receptive-field functions other than Gabor functions fit better. We conclude that there are insufficient theoretical demonstrations and experimental data to favor Gabor functions over any of a number of other plausible receptive-field functions.

Humans↗

PubMed1990

Some observations on the influence of vitamin D metabolites when added to the diet of commercial laying hens.

Three experiments were conducted to study the influence of two vitamin D3 metabolites on the performance of commercial laying hens. In Experiment 1, adding of .75, 1.50, 3.00, and 4.50 micrograms of 1 alpha-hydroxycholecalciferol (1 alpha-OHD3) or of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] per kg to the diet containing 2,200 ICU of vitamin D3 from 55 micrograms of cholecalciferol per kg of diet resulted in increased plasma calcium (Ca) and phosphorus (P). The response was greater from the 1,25-(OH)2D3 metabolite than from the 1 alpha-OHD3 metabolite. Neither metabolite affected tibia breaking strength (TBS), egg production (EP), egg weight (EW), feed consumption (FC), feed conversion, eggshell quality (ESQ), fertility, or the hatchability of eggs or the tibia ash (TA) of the day-old chick. In Experiment 2, the EP, EW, FC, ESQ and TA of the hens were not affected when 1.5 micrograms of 1,25-(OH)2D3 were added to each kilogram of a corn-soybean meal diet containing either .38 or .43% P with adequate vitamin D3. Adding the 1,25(OH)2D3 metabolite to the low-P diet reduced plasma Ca and increased TBS. However, adding 1,25-(OH)2D3 to the high-P diet increased plasma Ca and P. In Experiment 3, the EP, ESQ, FC, and TA of the hens were significantly lower when the diet contained 2.04% Ca rather than 3.04% Ca. Plasma Ca and P, EW, or TBS were not affected by the dietary Ca. Neither the plasma Ca and P, EP, EW, ESQ nor the TBS and TA were influenced by adding the 1,25-(OH)2D3 metabolite to either diet.

Animal Feed↗

PubMed1989

Human albinos can discriminate spatial frequency and phase as accurately as normal subjects.

Previous experiments testing grating and vernier acuities in albino central vision are consistent with the hypothesis that the deficit in their monocular spatial processing is mainly due to the increased spacing of their foveal cones. This was tested by measuring albino spatial frequency discrimination over the range 0.25-4.0 cpd. The same experiments were performed on three normal subjects both in the fovea and at a peripheral locus at which their grating acuity was identical to that of the albino subjects. Spatial frequency discrimination thresholds averaged 3.71% for albinos, 5.18% for the normal fovea, and 8.81% for the normal periphery, the latter being over 2.3 times greater than albino thresholds. A comparable pattern of results was observed in phase discrimination experiments. These data reject the possibility that albino central vision is similar to normal peripheral vision, but the results are predictable on the hypothesis that the central retina of albinos is a spatially magnified (underdeveloped) version of the normal fovea.

Adult↗

PubMed1989

In vivo efficacy of zidovudine (3'-azido-3'-deoxythymidine) in experimental gram-negative-bacterial infections.

The therapeutic efficacy of orally administered zidovuldine (3'-azido-3'-deoxythymidine) was determined in animals infected with Escherichia coli and Salmonella dublin. The 50% effective dose (ED50) of zidovudine (9.6 to 11.8 mg/kg of body weight) compared favorably with that of trimethoprim (19.4 to 22.2 mg/kg) in mice with systemic E. coli infection. At 50 mg/kg, both zidovudine and ampicillin reduced the number of bacteria in the kidneys of mice and prevented lethal infection in mice with ascending pyelonephritis caused by E. coli. Zidovudine prevented a lethal S. dublin infection in calves over a wide dose range (8.0 to 31.0 mg/kg per day). Zidovudine levels in plasma of uninfected mice were 28.2 +/- 4.5 and 7.9 +/- 2.2 micrograms/ml at 30 and 60 min, respectively, exceeding the MICs for the bacteria used in the infections. Few zidovudine-resistant strains were observed. The in vivo data raise the possibility that zidovudine may have an antibacterial effect in patients receiving this therapy.

Ampicillin↗

PubMed1989

Mechanisms of contour curvature discrimination.

Visual processing of contour curvature was investigated by measuring increment thresholds for curvatures from 0.31 to 25.4 deg-1. Curvature discrimination was assessed for three classes of stimuli: simple curved contours, high-frequency bandpass-filtered contours, and low-pass-filtered contours. High-frequency bandpass filtering had no effect on discrimination at low curvatures and only a modest effect at high curvatures. In contrast, low-pass filtering caused substantial threshold elevations at all curvatures. Thus the data lead to the surprising conclusion that high-spatial-frequency, orientation-selective mechanisms dominate curvature processing over the entire range of curvatures tested, a conclusion at odds with previous suggestions that large, low-spatial-frequency filters are involved in analyzing low curvatures. The data are explained accurately by a two-process model for curvature extraction: at high curvatures the local-processing model proposed by Wilson [J. Opt. Soc. Am. A. 2, 1191 (1985)] fits the data well, whereas at low curvatures orientations are compared at points displaced a fixed distance along the tangent to the curve.

Biomechanical Phenomena↗

PubMed1989

Feeding time and body temperature interactions in broiler breeders.

Four groups of 70-wk-old broiler breeder females were fed once daily at 0600, 1000, 1400, and 1800 h to determine the effect of feeding time and eating on body temperature. The photoperiod was from 0430 to 1930 h. Four floor pens of 30 hens each were assigned per feeding time. Following a 9-day adjustment period, body temperature was determined, in series, by rectal probe of 5 birds/pen at 7 and 3 h prefeeding and 1, 5, 9, and 13 h postfeeding. Body temperature was increased .5 C at 1 h postfeeding in all groups and at 5 h postfeeding in the 0600-h fed group. The rate of feed consumption was fastest with afternoon feeding. Four 1-yr-old broiler breeder males were implanted with an FM radio transmitter for monitoring body temperature and housed in an environmental control chamber. Body temperature was monitored when the birds were fed at 0600, 1000, 1400, and 1800 h. The chamber temperature cycled from 22.2 to 33.3 C (22.2 C: 2200 to 0800 h; 33.3 C: 1200 to 1600 h; 27.8 C: 0800 to 1200 h and 1600 to 2200 h). Lights were on from 0430 to 1930 h. Body temperature changes were also monitored under constant temperature (27.8 C) and light for birds fed ad libitum or at 1000 h. Body temperature increased as much as 1.5 C following feeding and reached a maximum at 5, 4, 3, and 2 h postfeeding at feeding times of 0600, 1000, 1400, and 1800 h, respectively. Males unable to feed displayed a significantly increased body temperature when they observed other birds eating. A specific body temperature response to feeding activity was observed only when males were fed once daily under constant environment.

Animal Feed↗

PubMed1989

Chick mortality in bobwhite quail as affected by supplemental ascorbic acid.

In two experiments, bobwhite quail chicks were given 0, 50, or 500 ppm ascorbic acid (AA) in the drinking water from 1 to 7 days of age. Both levels of AA significantly decreased mortality for the first 7 days and for the 3-wk average. Feed conversion during the entire 3-wk study was improved by 500 ppm AA. Body weight was not affected by AA supplementation.

Administration, Oral↗

PubMed1989

Effect of daily restriction and age at initiation of a skip-a-day program for young broiler breeders.

Two experiments were conducted with Cobb feather sex broiler breeders comparing skip-a-day (SAD) feeding programs which began at either 2, 4, 6 or 8 wk of age. A fifth program, daily restriction started at 2 wk of age, was also compared. Chicks hatched in December and July, respectively, in Experiments 1 and 2 were exposed to natural daylight until 20 wk of age. All birds were fed ad libitum until the respective restriction programs began. All grower programs terminated at 20 wk of age. A breeder diet was given daily after 20 wk. Males and females were grown together. Sexual maturity was reached earlier in the 2-wk restriction groups (2-wi SAD in Experiment 1 and the 2-wk daily restriction in both experiments) than in the 8-wk SAD group. Egg production in Experiment 1 was also improved by the early restriction. Fertility and hatchability were not significantly affected by treatment. Based on the results of these experiments a SAD program beginning at 2 wk of age was as good as or better than one initiated at later ages. The 2-wk daily restriction program was equivalent to the 2-wk SAD program.

Age Factors↗

PubMed1988

Structure of 3'-azido-3'-deoxythymidine, AZT.

C10H13N5O4, Mr = 267.2, monoclinic, P2(1), a = 5.716 (3), b = 11.998 (8), c = 17.658 (10) A, beta = 94.26 (4) degrees, V = 1208 A3, Z = 4, D chi = 1.47 g cm-3, lambda (Mo K alpha) = 0.71069 A, mu = 7.5 cm-1, F(000) = 560, T = 293 K. R = 0.060 for 2138 unique observed [F greater than 4 sigma (F)] reflections. The N-glycosidic torsion angles chi have values -125.9 (5) and -172.0 (5) degrees, in the anti range. (Molecule-A values are given first throughout.) The sugar puckers are 2(3)T (C3'-exo/C2'-endo), with P = 171 (1) degrees and psi m = 14 (1) degrees, and 4(3)T (C4'-endo/C3'-exo), with P = 213 (1) degrees and psi m = 11 (1) degrees. The C4-C5 conformations, with gamma = 49.7 (5) and 173.7 (5) degrees, are + sc (gauche-gauche) and ap (gauche-trans). The conformational parameters used follow the guidelines of the IUPAC-IUB Joint Commission on Biochemical Nomenclature [Pure Appl. Chem. (1983), 55, 1273-1280]. The molecules in the asymmetric unit form a hydrogen-bonded, base-paired dimer. The bonding is as follows: N3A-0.973 A-H3A... 1.790 A...O2B, N3A...O2B 2.747 (8) A, angle at H3A 167 degrees and N3B-0.992 A-H3B...1.916 A...O2A, N3B...O2A 2.894 (8) A, angle at H3B 168 degrees. The propeller twist between the bases is 5 degrees [Wilson & Tollin (1987). Nucleosides Nucleotides, 6, 643-653].

Molecular Structure↗

PubMed1988

NMR analysis of the interdomain region of yeast phosphoglycerate kinase.

Previous proton and phosphorus nuclear magnetic resonance studies with yeast phosphoglycerate kinase have been extended using a higher-resolution spectrometer and a greater variety of binding agents. The new study shows that, apart from a few isolated mobile side chains distributed over the protein surface, there is a mobile section of phosphoglycerate kinase associated with the inter-domain region of the molecule. This region gives relatively well resolved resonances which are quite distinct from those originating from the remainder of the protein. This suggests that the molecule fluctuates between many states including several open or substrate binding forms in addition to the closed and supposedly catalytically competent form of the enzyme. The occupancy of these states appears to be affected by several anions including sulphate, phosphate and cobalticyanide, as well as substrates and their analogues.

Binding Sites↗

PubMed1988

Albino spatial vision as an instance of arrested visual development.

Adult albinos and human infants share a number of common visual characteristics: both have low grating acuity, both lack a foveal pit (foveal hypoplasia), and both have much lower central cone densities than in the normal adult. We have explored the consequences of these characteristics by measuring both spatial and temporal contrast sensitivity in the central retina and by comparing central and peripheral grating and vernier acuities in two young adult albino subjects. To compensate for nystagmus, horizontally oriented patterns were employed. Both subjects had normal flicker sensitivities, but their central grating and vernier acuities were approximately five times worse than normal. At 10.0 degrees in the inferior visual field, however, vernier and grating acuities were normal for both subjects. Finally, the ratio of grating to vernier acuity in albino central vision fell within the normal foveal range, suggesting that albino central vision does not resemble the adult periphery. These results are consistent with the hypothesis that spatial processing deficiencies in albino central vision are a direct consequence of the increased spacing of their central cones. Our data are comparable to available psychophysical results obtained from infants of approx. 10 months of age, thus suggesting that the albino visual system may represent a case of arrested development.

Adult↗