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Biomedical subjects

N H Williams

Publications and source records attributed to N H Williams.

At least 19 recordsLinked to original sources
PubMed2007

Dietary B vitamin needs of strains of pigs with high and moderate lean growth.

Ten sets of 5 littermate pigs from each of 2 genetic strains were utilized to determine the impact of the dietary concentration of 5 B vitamins (riboflavin, niacin, pantothenic acid, cobalamin, and folacin) on growth from 9 to 28 kg of BW in pigs with high or moderate capacity for lean growth. All pigs (penned individually) were reared via a segregated, early weaning scheme, so that the lean growth potential of each strain could be expressed. The basal diet provided the 5 test vitamins at concentrations of total and estimated bioavailability equivalent to a minimum of 100 and 70%, respectively, of their estimated requirements (NRC, 1998) for 5- to 10-kg pigs. At a BW of 9 +/- 0.9 kg, pigs within each litter were allotted to the basal diet supplemented with sources of the 5 test vitamins equivalent to an additional 0, 100, 200, 300, or 400% (bioavailable) of the NRC requirements. Pigs from the high lean strain consumed less feed (P < 0.05) and gained BW faster (P < 0.02) and more efficiently (P < 0.01) than pigs of the moderate lean strain. In both lean strains, the rate and efficiency of growth were improved (P < 0.01) as dietary B vitamin concentrations were increased. However, the dietary B vitamin concentrations needed to optimize G:F were greater (P < 0.03) in the high (>470% of NRC, 1998) vs. moderate (270%) lean strain. Based on these data, the dietary needs for 1 or more of the 5 B vitamins are greater than current NRC (1998) estimates, particularly in pigs expressing a high rate of lean tissue growth. The greater need for these vitamins is not associated with greater dietary energy intake or body energy accretion rate but is potentially due to shifts in the predominant metabolic pathways.

Animal Feed↗
PubMed2000

Subtribal and generic relationships of Maxillarieae (Orchidaceae) with emphasis on Stanhopeinae: combined molecular evidence.

The monophyly of and phylogenetic relationships within the orchid tribe Maxillarieae Pfitzer were evaluated using parsimony analyses of combined nuclear ribosomal and plastid DNA sequence data of ITS 1 and 2, matK, and the trnL intron and the trnL-F intergene spacer. Each of the separate analyses produced highly congruent but weakly supported patterns (by the bootstrap), so these were combined in a single analysis. Analysis of 90 ingroup taxa (representing ∼35% of currently recognized genera) and four outgroup taxa produced resolved and highly supported cladograms. Based on the cladograms, we recognize six subtribes: Eriopsidinae, Oncidiinae (including Pachyphyllinae, Ornithocephalinae, and Telipogoninae), Stanhopeinae, Coeliopsidinae, Maxillariinae (including Lycastinae and Bifrenariinae), and Zygopetalinae (including Cryptarrheninae, Dichaeinae, Huntleyinae, and Warreinae). Stanhopeinae were sampled most intensively; their generic relationships were highly resolved in the analysis and largely agree with currently accepted generic concepts based on morphology. Coeliopsidinae (Coeliopsis, Lycomormium, Peristeria) are sister to Stanhopeinae. Correlations are drawn among phylogeny, pollination mechanisms, and life history traits.

Journal Article↗
PubMed1998

Effect of lean growth genotype and dietary amino acid regimen on the lactational performance of sows.

The effect of dietary amino acid regimen and genetic capacity for lean tissue growth on the lactational performance of sows was determined in primiparous sows with a high (350 to 390 g/d) or low (240 to 280 g/d) genetic capacity for lean tissue growth from 18 to 110 kg of body weight. During lactation, sows were offered daily 6.5 kg of one of four fortified corn-soybean meal diets containing .58, .77, .96, and 1.15% lysine (L). Litters were standardized to 14 pigs within 8 h after birth. On d 2 of lactation, the high lean growth (LG) sows possessed more proteinaceous tissues and protein and less fat tissue and lipid. During lactation (d 2 to 28 postpartum), high LG sows consumed more feed, mobilized more body protein, and lost less body lipid. Milk, milk energy, and milk lysine yields (pooled across dietary regimens) were similar between genotypes. As daily dietary lysine intakes increased from 27 to 62 g and total digestible lysine supplies (from diet and mobilized tissues) increased from 39 to 68 g, daily yields of milk, milk energy, and milk lysine increased, but the magnitude of the response differed (P < .05) between genotypes, evidently because of differences in the ability of the high and low LG sows to mobilize energy from body tissue. Based on these data, the lactational capacities of high and low LG sows nursing 12 to 14 pigs are similar when similar supplies of lysine and energy are available from dietary intake and mobilized body tissue stores. When supplies of ME do not limit milk synthesis, daily digestible lysine intakes of at least 54 g (> or = 66 g from a corn-soy diet) are needed by these sows nursing litters of 12 to 14 pigs to support milk synthesis and minimize maternal protein losses. This is equivalent to a total digestible lysine need of 4.3 to 4.6 g/kg of milk produced. When ME provided by the diet is less than that needed to fuel maximum milk synthesis, however, the dietary amino acid needs of genetically lean sows may be reduced because of their inability to mobilize sufficient body fat stores.

Analysis of Variance↗
PubMed1997

Student teacher anxieties related to class management, pedagogy, evaluation, and staff relations.

BACKGROUND: Anxiety is an important consideration in teaching, with implications for classroom success. AIMS: We investigated the nature of anxiety in student teachers. SAMPLES: Approximately 1000 student teachers in Canada were involved in four studies to explore education-related anxieties. METHODS: Incorporating a cross-cultural focus, student teachers were tested on an anxiety measure designed for British student teachers, then examined for (1) the impact of practice teaching, (2) the value of instructional preparation, (3) demographic variables, and (4) models that predict anxiety. RESULTS: Anxiety factors (i.e., evaluation, pedagogical, class management, and staff relations), similar to those for British participants, emerged with evaluation anxiety being highest. A practice teaching experience generated reduced anxiety for both sexes, but more so for females, with the greatest reductions for evaluation and pedagogical anxiety. In one study, participants reported anxieties prior to instruction (PRETEST), following instruction (POST-INSTR) and following practice teaching (POST-TEACH). Females showed higher anxiety ratings than males (PRETEST and POST-INSTR) but were comparable to males after practice teaching. Females in the lower grades division showed higher anxiety scores. Anxiety decreased between PRE-TEST and POST-INSTR for all four scales, and between POST-INSTR and POST-TEACH for evaluation, pedagogy and staff relations; however, class management anxiety did not decrease after practice teaching. Also, anxiety increased as placement grade level decreased. All models (demographic, experiential, and dispositional) were predictive but the best predictor was the psychological disposition to feel overwhelmed. CONCLUSIONS: Student-teacher anxieties are related to demographic variables, experiential variables, and dispositional variables.

Adult↗
PubMed1997

Effect of chronic immune system activation on the rate, efficiency, and composition of growth and lysine needs of pigs fed from 6 to 27 kg.

The influence of a low and a high level chronic immune system (IS) activation on growth and dietary nutrient needs of pigs was evaluated. All pigs were of a single genetic strain and geographical site of origin, and the low and high IS pigs were created by physically isolating pigs from or continuously exposing pigs to major vectors of environmental antigen transmission. In each IS group, four littermate barrows in each of six litters were allotted at 25 +/- 2 d of age to one of four dietary amino acid regimens (.60, .90, 1.20, or 1.50% dietary lysine. Dietary lysine concentrations were achieved by altering the ratio of corn to soybean meal resulting in lysine being the first-limiting amino acid in each diet. Pigs were individually penned in facilities maintained at 25.6 +/- 2 degrees C and allowed to freely consume feed from 6.2 to 26.5 kg BW. On the basis of the differences in serological antibody titers, lymphocyte CD4+:CD8+ ratios, and serum alpha-1-acylglycoprotein concentrations, low and high levels of IS activation were established and maintained during the study. Minimizing the degree of chronic IS activation resulted in greater feed intakes (P < .09), body weight and protein gains (P < .01), gain:feed ratios (P < .01), and body leanness (protein:lipid, P < .01). The level of IS activation did not influence the partial efficiency of energy utilization for body protein and lipid accretion. To allow their greater capacity for body growth and protein accretion to be expressed, the low IS pigs required greater dietary lysine concentrations and daily lysine intakes than high IS pigs.

Animals↗
PubMed1997

Effect of chronic immune system activation on body nitrogen retention, partial efficiency of lysine utilization, and lysine needs of pigs.

The influence of a low and high level of chronic immune system (IS) activation on body nitrogen retention, partial efficiency of dietary lysine utilization, and lysine needs of pigs at three body weights was determined. All pigs were of a single genetic strain and geographical site of origin, and the low and high IS pigs were created by physically isolating pigs from or continuously exposing pigs to major vectors of antigen transmission. In each IS group, four littermate barrows in each of six litters were allotted at 25 d of age to one of four dietary amino acid regimens (.60, .90, 1.20, or 1.50% dietary lysine). Pigs were individually penned and allowed to freely consume feed from 6.2 to 26.5 kg BW. Nitrogen balance during 4-d periods was determined for each pig at BW of 10, 17.5, and 25 kg. Minimizing the level of chronic IS activation resulted in 4.7 to 7.7 g/d greater body nitrogen retention, 147 to 201 g/d greater BW gain, and 101 to 147 g more gain per kilogram of feed in pigs at the three BW. Dietary lysine intakes needed to maximize each of these criteria at BW of 10, 17.5, and 25 kg were a minimum of 2, 2, and 3 g/d greater in the low vs high IS pigs. However, the partial efficiency of lysine utilization for body nitrogen retention was similar between IS groups. On the basis of these data, the greater dietary lysine needs of the low IS pigs are due to their greater biological capacity for body nitrogen accretion and not to differences in their efficiency of dietary lysine utilization.

Animals↗
PubMed1997

Effect of level of chronic immune system activation on the growth and dietary lysine needs of pigs fed from 6 to 112 kg.

The effect of a low and a high level of chronic immune system (IS) activation on the rate, efficiency, and composition of body growth and dietary lysine needs of pigs fed from 6 to 112 kg body weight was evaluated. All pigs were of a single genetic strain and geographical site of origin, and the low and high IS pigs were created by physically isolating pigs from and continually exposing pigs to major vectors of environmental antigen transmission. In each IS group, five littermate barrows from each of seven litters were individually penned and randomly allotted to one of five dietary amino acid regimens (.6, .9, 1.20, 1.50, and 1.80% lysine from 6 to 27 kg BW and .45, .60, .75, .90, and 1.05% lysine from 27 to 112 kg BW). Dietary lysine concentrations were achieved by altering the ratio of corn to soybean meal in the diets, and diets were formulated such that lysine was the first-limiting amino acid. Low IS pigs possessed lower (P < .01) T lymphocyte CD4+:CD8+ ratios and serum alpha-1-acylglycoprotein concentrations. Low IS pigs also consumed more (P < .01) feed, gained body weight faster (P < .01), required less (P < .01) feed per unit of gain, and at 112 kg BW produced bodies with more (P < .12) muscle and less (P < .10) fatty tissue and offal than high IS pigs. To allow their elevated capacities for proteinaceous tissue to be expressed, low IS pigs required .15 to .30 percentage units greater dietary lysine concentrations and 2 to 5 g higher daily lysine intakes at each 14-kg BW increment from 6 to 112 kg BW.

Animals↗
PubMed1994

The impact of ractopamine, energy intake, and dietary fat on finisher pig growth performance and carcass merit.

An experiment was conducted to determine the effect of ractopamine, energy intake, dietary fat level, and sex on performance and carcass composition in finishing pigs. Three hundred six barrows and gilts were used in a factorial arrangement of treatments replicated over three seasons. Treatments consisted of two ractopamine levels (0 vs 44.7 mg/d), two sexes (barrows and gilts), two levels of fat addition (0 vs 5% added fat), and four energy intake levels (8.3, 8.9, 9.5, and 10.1 Mcal of ME/d for barrows and 7.7, 8.3, 8.9, and 9.5 Mcal of ME/d for gilts). Diets were formulated to maintain an equal lysine (28.5 g/d) intake at each feeding level through cornstarch dilution of the basal (7.7 Mcal of ME/d) diets. Pigs were fed daily based on a standard feed intake curve and prior weekly body weights. At slaughter (104 kg), carcass measurements and TOBEC HA-1 scanner measurements were recorded. Dietary fat addition improved live weight and lean efficiency (grams of carcass lean gain/kilogram of feed, P < .05). Dietary fat addition did not affect growth rate or carcass composition. Increasing energy intake resulted in a linear increase in average daily gain for both barrows and gilts (P < .01). Dietary ractopamine influenced the response of lean tissue accretion, lean tissue accretion efficiency, and fat tissue accretion to energy intake. Pigs with no added ractopamine demonstrated increased lean tissue accretion and improved efficiency and decreased fat tissue accretion with increasing energy intake (up to 9.5 Mcal of ME intake for barrows and 8.9 Mcal of ME intake for gilts). In contrast, pigs with added ractopamine did not respond to increasing energy intake and demonstrated increased fat tissue accretion with increasing energy intake. The response to ractopamine for growth was greatest from d 6 to 22 on test or during the test gain period of 7 to 18 kg. After d 22, the response of ractopamine declined linearly. These results indicate that ractopamine increases growth rapidly at the onset of feeding until a plateau is reached, after which there is a linear decline in growth response.

Adipose Tissue↗
PubMed1994

Hemisphericity and information processing in North American Native (Ojibwa) and non-native adolescents.

Thirty-two male and female adolescents of native ancestry (Ojibwa) and 32 controls were tested using (1) four WISC-R subtests and (2) two dichotic listening tasks which employed a focused-attention paradigm for processing consonant-vowel combinations (CVs) and musical melodies. On the WISC-R, natives scored higher than controls on Block Design and Picture Completion subtests but lower on Vocabulary and Similarities subtests. On laterality measures more native males showed a left ear advantage on the CV task and the melody task. For CVs the left ear advantage was due to native males' lower right ear (i.e., left hemisphere) involvement. For melodies, the laterality index pointed to less left hemisphere involvement for native males, however, the raw scores showed that natives were performing lower overall. The findings are consistent with culturally-based strategy differences, possibly linked to "hemisphericity," but additional clarifying research regarding the cause and extent of such differences is warranted. Thus, implications for education are premature but a focus on teaching "left hemisphere type" strategies to all individuals not utilizing such skills, including many native males, may prove beneficial.

Adolescent↗
PubMed1985

Reduction of oxidized cytochrome c by ascorbate ion.

The kinetics and mechanism of the reduction of oxidized cytochrome c by ascorbate has been investigated in potassium nitrate, potassium 4-morpholineethanesulfonate (KMes), potassium sulfate and potassium ascorbate media. The results are consistent with simple second order electron transfer from ascorbate dianion to cytochrome c and do not support electron transfer from an ascorbate dianion bound to the protein of the cytochrome as recently proposed by Myer and Kumar. A rate constant of 8 X 10(5) M-1 X s-1 (25 degrees C, ionic strength, 0.1) was found for the electron-transfer step. This rate constant is essentially independent of the specific ions used in controlling ionic strength.

Alkanesulfonates↗
PubMed1983

Ontogeny and characterization of mitogen-reactive lymphocytes in the thymus and spleen of the amphibian, Xenopus laevis.

The ontogeny of the proliferative response of Xenopus thymocytes to the T-cell mitogens concanavalin A (Con A) and phytohaemagglutinin and to the B-cell mitogen E. coli lipopolysaccharide (LPS) is examined during the first 2 years of life. Responses after metamorphosis are compared with those occurring in the spleen. During much of larval life, mitogen-treated thymocytes display no sign of elevated [3H]TdR uptake. A low level in vitro response to Con A and LPS emerges transiently just prior to metamorphosis, the latter period being associated with a temporary disruption of thymocyte mitogen reactivity. Appreciable stimulation of both thymocytes and splenocytes with all three mitogens emerges within the first few months post-metamorphosis, and, with the exception of the thymocyte response to LPS, these induced proliferative levels are maintained or increased in toadlets aged 7-24 months. Maximal levels of LPS responsiveness in thymocyte cultures are found at 6 months of age. LPS-induced thymocyte proliferation at this time is confirmed morphologically by autoradiography; furthermore, immunofluorescence experiments, using an anti-Xenopus-mu chain antiserum, reveal that LPS induces the differentiation of cytoplasmic IgM cells in both spleen and thymus. The results indicate the presence of substantial populations of mitogen-sensitive cells in B lineage in the anuran thymus.

Aging↗
PubMedDate not supplied

Creating an educational videotape.

Staff development and patient education coordinators are challenged to lead efforts to provide resources for patient education. One option to provide cost-effective, quality education is the use of videotapes. In this article, the authors identify six advantages of video instruction and detail the steps to create an educational videotape.

Education, Nursing, Continuing↗
PubMedDate not supplied

Time-of-day-induced priming effects on verbal and nonverbal dichotic tasks in male and female adult subjects.

Normal adults (32 males and 32 females) were tested for time-of-day related shifts in laterality and priming on two dichotic listening tasks using consonant-vowel combinations (CVs) and musical melodies. The predicted time-of-day effect on melodies was due to males showing low report in the morning, but not the afternoon, suggesting increased right hemisphere involvement in the afternoon. A time-of-day-induced priming effect on the laterality index for CVs differentiated males and females. Males tested morning-first were more lateralized than females, who in turn were more lateralized when tested afternoon-first. A time-of-day-induced priming effect on the laterality index for music indicated those tested afternoon-first showed an overall left ear advantage (LEA), whereas those tested morning-first showed an overall right ear advantage (REA). On raw music scores a sex-linked, time-of-day-induced priming effect was due to the prior presentation of CVs--that is, cognitive priming. Other priming effects on music were evident for order of stimulus presentation and order of ear attended. Implications for theory, research and pedagogy are discussed.

Adult↗