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Biomedical subjects

B A Watkins

Publications and source records attributed to B A Watkins.

At least 37 records · Page 2Linked to original sources
PubMed2000

Ascorbic acid supplementation improved antibody response to infectious bursal disease vaccination in chickens.

The purpose of the present study was to determine if supplementation of ascorbic acid (AA) to the diet would have a beneficial effect on infectious bursal disease (IBD) vaccination of chickens for protection against infectious bursal disease virus (IBDV) infection. Two hundred forty specific pathogen-free (SPF) chickens were divided into eight experimental groups. A 2 x 2 x 2 factorial arrangement in a completely randomized design was used; AA supplementation at 1,000 ppm in the diet, vaccination, and challenge were the main effects. Prior to challenge and 10 d after challenge, serum AA concentration, serum corticosterone concentration, ELISA antibody titer to IBDV, body weight, bursa-to-body weight (B:B) ratio, and bursal histological score (BHS) were determined. Nonvaccinated chickens fed a diet supplemented with AA did not exhibit clinical signs or mortality following challenge, whereas AA-unsupplemented counterparts had 100% cumulative morbidity and 30% cumulative mortality. Serum AA levels of AA-supplemented and vaccinated chickens were significantly (P < 0.05) higher than AA-unsupplemented and vaccinated chickens. Fourteen days following vaccination, significantly (P < 0.05) higher ELISA titers to IBDV were observed in vaccinated chickens supplemented with AA as compared to AA-unsupplemented counterparts. Ascorbic acid-supplemented chickens, especially those also vaccinated, had higher body weight gains as compared to the AA-unsupplemented chickens. Ascorbic acid-supplemented chickens challenged with IBDV did not show any clinical signs or mortality. The results suggest that supplementation of AA at 1,000 ppm in the diet has beneficial effects on antibody response to IBD vaccination and body weight gain.

Animals↗
PubMed2000

Effects of conjugated linoleic acid. 1. Fatty acid modification of yolks and neonatal fatty acid metabolism.

The purpose of this study was to evaluate the effects of conjugated linoleic acids (CLA) on neonatal fatty acid metabolism. In this study, layer hens (n = 40) were divided into four equal groups and subjected to the following treatments. Group A served as the control group, Group B received 1 g CLA every other day, Group C received 1 g CLA every 4th d, and Group D was sham-supplemented with 1 g safflower oil every other day. After 4 mo of feeding, Group B hens exhibited an increase in BW and egg size; however, there were no differences noted in feed consumption among the various treatment groups. At the same time, hens were inseminated with a constant dose of pooled rooster semen to evaluate changes in chick liver and yolk fatty acid metabolism during neonatal growth. At hatch and through 6 d of age, there were no significant differences in breakout data (fertility and numbers of early-, mid-, or late-dead chicks) or chick BW, respectively. However, Group B chicks exhibited an increase in liver 18:3n3 and 22:1n9 and a decrease in 20:3n6 and 22:5n3 fatty acids when compared with chicks from Groups A and D. Also noted for Group B chicks, yolk 18:0 fatty acid was higher than that for Group A and D chicks. These results suggest that CLA alters lipid metabolism in growing chicks.

Animals↗
PubMed2000

Effects of conjugated linoleic acid. 2. Embryonic and neonatal growth and circulating lipids.

The present study was designed to investigate the effects of conjugated linoleic acid (CLA) on yolk usage and circulating very low density lipoproteins (VLDL) during incubation (Day 15) and through 6 d post-hatch. Eggs enriched with CLA were obtained from hens subjected to the following treatments. Group A hens served as the control group, Group B hens received 1 g CLA every other day, Group C hens received 1 g CLA every 4th d, and Group D hens were sham-supplemented with 1 g safflower oil every other day. Enrichment with CLA did not effect fertility, hatch of fertile, BW, or yolk-free BW of embryos or chicks. However, there were significant changes in relative yolk sac weight (RYW) and composition of circulating VLDL particles. Across all dietary treatments (Groups B, C, and D), 15-d embryos had smaller RYW compared with Group A embryos; this difference remained through 2 d posthatch. During that period (15 d of incubation through 2 d posthatch), however, embryos and chicks from Group B hens exhibited a unique absorption pattern such that little to no yolk was utilized between hatch and 2 d posthatch, a period normally characterized by high yolk lipid utilization. Similar to the RYW effects, VLDL particles were also altered by hen-induced treatment. Specifically, at hatch, chicks from Group A hens had the highest percentage of triglycerides (TG) within their VLDL particles compared with chicks from hens under all other treatments. This trend in VLDL particles was continued at 4 d posthatch. The present study demonstrates that CLA enrichment of eggs alters relative yolk sac absorption and the composition of circulating VLDL particles.

Animals↗
PubMed2000

Perturbations in factors that modulate osteoblast functions in vitamin B6 deficiency.

It was hypothesized that the widespread structural defect of collagen in connective tissue of vitamin B6 deficient-animals and the consequent alteration in bone biomechanical properties cause an additional stress to their inflamed swollen tibiotarsometatarsal joints. The present study showed a 32% elevation (P < 0.02) in mean plasma free cortisol concentration. Vitamin D metabolism was impaired but without changing plasma calcium homeostasis and bone mineral content. Mean plasma calcitriol [1,25(OH)2D] concentration was significantly reduced (P < 0.001). Because plasma calcidiol concentration did not change, we speculated that either renal 25-hydroxycalciferol-1alpha-hydroxylase activity was reduced or 1,25(OH)2D turnover was increased. Plasma osteocalcin, an index of osteoblast function related to bone formation, was significantly decreased (P < 0.05). This adverse effect on osteoblasts was consistent with the reduction of bone specific alkaline phosphatase activity (another index of bone formation) found in a previous study. The excess of cortisol may have impaired these bone cells functions directly and (or) indirectly via the decline in calcitriol synthesis. Plasma hydroxyproline concentrations in B6-deficient animals were found to be significantly reduced (P < 0.001), suggesting that cortisol in excess had also a suppressive effect on another hydroxylase, namely tissue (mainly bone and liver) prolyl hydroxylase. The bone uncoupling (in formation and resorption) associated with vitamin B6 deficiency seems to be due to secondary hypercortisolism and (or) another unknown factors but not related to a change in bone modulators such as IGF-1 and eicosanoids.

Animals↗
PubMed1999

Dietary conjugated linoleic acid influences the immune response of young and old C57BL/6NCrlBR mice.

Aging is associated with a decline in the immune response in mammals. Conjugated linoleic acid (CLA) has been suggested to have immunoenhancing properties. We examined the influence of dietary CLA on the immune response of young and old mice. Forty young (4 mo) and 40 old (22 mo) mice consumed ad libitum diets containing 0 or 1 g CLA /100 g for 8 wk. Splenocytes from half of the mice were isolated to evaluate proliferation to concanavalin A (Con A) (0.5, 1.5, 5.0 mg/L) and phytohemagglutinin A (PHA) (5, 20, 40 mg/L) and lipopolysaccharide (LPS) (5, 15, 30 mg/L), natural killer cell (NK) activity and prostaglandin (PG)E2 and interleukin (IL)-2 production. The remaining mice were used to evaluate in vivo delayed-type hypersensitivity (DTH) skin response. There was a significant decline due to age in response to all three mitogens tested (P < 0. 05). CLA supplementation significantly increased all CLA isomers measured in hepatic neutral lipids and phospholipids (P < 0.05). Young mice fed 1% CLA had greater splenocyte proliferation in response to Con A (0.5 and 5.0 mg/L) and PHA (40 mg/L) (P < 0.05) than young mice fed control diet. Old mice fed 1 g CLA/100 g had significantly higher proliferative response to optimal concentrations of Con A (1.5 mg/L) (P < 0.001) than the mice fed the control diet. Old mice fed the control diet had significantly lower splenocyte IL-2 production than the young mice (P < 0.005). CLA-supplemented young mice had significantly higher splenocyte IL-2 production than those fed the control diet (P < 0.05). CLA had no effect on NK cell activity, PGE2 production or DTH in young or old mice. Further studies are needed to determine the mechanism of CLA-induced enhancement of IL-2 production and T cell proliferation.

Aging↗
PubMed1999

Effect of ingredients and processing parameters on pellet quality.

Rations containing varying ratios of corn, high-oil corn, soybean meal, and mechanically expelled soybean meal were pelleted. The effects of ingredients, conditioning steam pressure, and mixing paddle configuration inside the conditioner on pellet quality were investigated. Ration ingredients strongly affected pellet quality. Increasing the protein content increased the pellet durability, whereas increasing the oil content above 7.5% greatly decreased pellet durability. High-oil corn and mechanically expelled soybean meal produced acceptable pellets when combined with soybean meal and regular corn, respectively. However, poor pellet quality resulted when rations containing high-oil corn and mechanically expelled soybean meal were processed. Increasing the residence time in the conditioner by changing mixing paddle pitch resulted in an average 4.5-point increase in pellet durability indices among 65:35 (wt) corn:soybean meal and 65:35 high-oil corn:soybean meal rations.

Animal Feed↗
PubMed1999

Dietary conjugated linoleic acids alter serum IGF-I and IGF binding protein concentrations and reduce bone formation in rats fed (n-6) or (n-3) fatty acids.

A study was designed to examine the effects of dietary conjugated linoleic acid (CLA) on serum concentrations of insulin-like growth factor-I (IGF-I) and IGF binding proteins (IGFBP) and the relationship of these factors to bone metabolism. Weanling male rats were fed AIN-93G diet containing 70 g/kg of added fat for 42 days. Treatments included 0 g/kg or 10 g/kg of CLA and soybean oil (SBO) or menhaden oil + safflower oil (MSO) following a 2 x 2 factorial design. Serum IGFBP was influenced by dietary polyunsaturated fatty acid (PUFA) type ((n-6) and (n-3)) and CLA (p = 0.01 for 38-43 kDa bands corresponding to IGFBP-3). CLA increased IGFBP level in rats fed SBO (p = 0.05) but reduced it in those fed MSO (p = 0.01). Rats fed MSO had the highest serum IGFBP-3 level. Both (n-3) fatty acids and CLA lowered ex vivo prostaglandin E2 production in bone organ culture. In tibia, rats given CLA had reduced mineral apposition rate (3.69 vs. 2.79 microm/day) and bone formation rate (BFR) (0.96 vs. 0.65 microm3/microm2/day); however, the BFR tended to be higher with MSO. Dietary lipid treatments did not affect serum intact osteocalcin or bone mineral content. These results showed that dietary PUFA type and CLA modulate local factors that regulate bone metabolism.

Animals↗
PubMed1998

Effects of high-fat diet on mature bone mineral content, structure, and mechanical properties.

Diets with a high saturated fat content can produce deleterious effects on the absorption of dietary calcium and consequently an adverse effect on bone mineralization in growing animals. Hence dietary fat may have long-term consequences for skeletal health and skeletal pathologies such as osteoporosis. Whether a diet high in saturated fat has similar negative effects on adult bone, however, remains unresolved. Thus, we investigated effects of a high-fat diet on mature bone structure and mechanics. Adult (40-week-old) roosters were maintained for 20 weeks on either a diet high in saturated fat (HF) or a low-fat (LF) diet. Cortical bone samples (tarsometatarsus) were tested mechanically in three-point bending, and cancellous bone cores from the femoral condyles and tibial plateau (four sites per knee) were tested mechanically in compression. Cortical bone cross-sectional areal data were also compared among the groups, and bone mineral content (BMC) was determined (by ashing) for both cortical bone and cancellous bone samples. There were no significant high-fat diet effects on mature cortical bone mechanical properties, geometric structure, or mineral content. Diet, however, did affect cancellous bone composition. For example, LF cancellous BMC was significantly greater than HF. Mechanical properties of the cancellous bone showed similar trends such that LF cancellous bone strength was consistently greater than HF. The potential for adverse effects of a HF diet on intestinal calcium absorption in the mature animal may be more apparent in cancellous bone, with its faster rate of turnover, than in cortical bone. Changes in cancellous bone structure and mechanical properties, related to dietary saturated fats, may have implications for understanding the role of nutrition in skeletal health and prevention of pathological bone loss (osteoporosis).

Age Factors↗
PubMed1998

Conjugated linoleic acids alter bone fatty acid composition and reduce ex vivo prostaglandin E2 biosynthesis in rats fed n-6 or n-3 fatty acids.

This study evaluated the effects of conjugated linoleic acids (CLA) on tissue fatty acid composition and ex vivo prostaglandin E2 (PGE2) production in rats given diets varying in n-6 and n-3 fatty acids. Four groups of rats were given a basal semipurified diet (AIN-93G) containing 70 g/kg of added fat for 42 d. The fat treatments were formulated to contain CLA (0 vs. 10 g/kg of diet) and n-6 (soybean oil having an n-6/n-3 ratio of 7.3) and n-3 fatty acids (menhaden oil + safflower oil having an n-6/n-3 ratio of 1.8) in different ratios in a 2 x 2 factorial design. Fatty acids in liver, serum, muscle, heart, brain, spleen, and bone (cortical, marrow, and periosteum) were analyzed by capillary gas-liquid chromatography. The various dietary lipid treatments did not affect growth; however, CLA improved feed efficiency. The CLA isomers were found in all rat tissues analyzed although their concentrations varied. Dietary CLA decreased the concentrations of 16:1n-7, 18:1, total monounsaturates and n-6 fatty acids, but increased the concentrations of n-3 fatty acids (22:5n-3 and 22:6n-3), and saturates in the tissues analyzed. Ex vivo PGE2 production in bone organ culture was decreased by n-3 fatty acids and CLA. We speculate that CLA reduced the concentration of 18:1 fatty acids by inhibiting liver delta9-desaturase activity. The fact that CLA lowered ex vivo PGE2 production in bone organ culture suggests that these conjugated fatty acids have the potential to influence bone formation and resorption.

Animal Feed↗
PubMed1997

Storage stability of screwpress-extracted oils and residual meals from CELSS candidate oilseed crops.

The efficacy of using screwpress extraction for oil was studied with three Controlled Ecological Life-Support System (CELSS) candidate oilseed crops (soybean, peanut, and canola), since use of volatile organic solvents for oil extraction likely would be impractical in a closed system. Low oil yields from initial work indicated that a modification of the process is necessary to increase extraction efficiency. The extracted oil from each crop was tested for stability and sensory characteristics. When stored at 23 degrees C, canola oil and meal were least stable to oxidative rancidity, whereas peanut oil and meal were least stable to hydrolytic rancidity. When stored at 65 degrees C, soybean oil and canola meal were least stable to oxidative rancidity, whereas peanut oil and meal were least stable to hydrolytic rancidity. Sensory evaluation of the extracted oils used in bread and salad dressing indicated that flavor, odor intensity, acceptability, and overall preference may be of concern for screwpress-extracted canola oil when it is used in an unrefined form. Overall results with screwpress-extracted crude oils indicated that soybean oil may be more stable and acceptable than canola or peanut under typical storage conditions.

Arachis↗
PubMed1997

Humanization of an antibody recognizing a breast cancer specific epitope by CDR-grafting.

BACKGROUND: Muc1-H23 is a cell surface mucin that is expressed on normal breast luminal epithelial cells and over-expressed in most breast tumors. In addition, Muc-1 expressed by malignant cells is glycosylated differently than Muc-1 expressed by normal cells. This difference in glycosylation exposes a peptide epitope on malignant cells which is not exposed on normal cells. Murine monoclonal antibody H23 recognizes this epitope and stains 91% of breast cancers, but only 1/56 non-malignant breast tissue samples. OBJECTIVE: To create a human antibody that was equivalent to H23 for potential uses in imaging and/or the therapy of breast cancer. STUDY DESIGN: We decided to humanize H23 by CDR-grafting using overlap PCR, and to this end, designed and constructed a bacterial expression vector that would allow V-regions, cloned via unique restriction sites, to be expressed as Fab fragments. In this way, we hoped to be able to rapidly evaluate Fab constructs for binding to Muc-1 and to cells and tissue sections that expressed the antigen. RESULTS: A fully humanized Fab fragment was able to bind Muc-1 peptide, as well as breast cancer cells known to express the epitope and tissue sections, generally showing the same reactivity as the native antibody. In addition, an analysis of sFab expressed with a [His]6 tag preceded by a factor Xa proteolytic cleavage site suggested that E. coli periplasmic signal peptidase was able to cleave the factor Xa site, thereby removing the [His]6 tag. CONCLUSION: We have generated a human antibody that is capable of recognizing a tumor specific epitope expressed by 91% of breast cancers.

Antigens, Neoplasm↗
PubMed1997

Dietary lipids modulate bone prostaglandin E2 production, insulin-like growth factor-I concentration and formation rate in chicks.

This study examined the effects of dietary fat on the fatty acid composition of liver and bone, and on the concentration of insulin-like growth factor-I (IGF-I) in liver and bone, as well as the relationship of these factors to bone metabolism. Day-old male broiler chicks were given a semipurified diet containing one of four lipid sources: soybean oil (SBO), butter+corn oil (BC), margarine+corn oil (MAC), or menhaden oil+corn oil (MEC) at 70 g/kg of the diet. At 21 and 42 d of age, chicks fed MEC had the highest concentration of (n-3) fatty acids [20:5(n-3), 22:5(n-3) and 22:6(n-3)] in polar and neutral lipids of cortical bone but the lowest amount of 20:4(n-6) in polar lipids. Diets containing t-18:1 fatty acids (MAC and BC) resulted in t18:1 accumulation in bone and liver. Bone IGF-I concentration increased from 21 to 42 d in chicks given the SBO and BC diets. Tibial periosteal bone formation rate (BFR) was higher in chicks given BC compared with those consuming SBO and MEC at 21 d. The higher BFR and concentrations of hexosamine in serum and IGF-I in cartilage, but lower 20:4(n-6) content in bone polar lipids in chicks given BC compared with those given SBO suggest that BC optimized bone formation by altering the production of bone growth factors. A second study confirmed that dietary butter fat lowered ex vivo prostaglandin E2 production and increased trabecular BFR in chick tibia. These studies showed that dietary fat altered BFR perhaps by controlling the production of local regulatory factors in bone.

Animals↗
PubMed1997

Syncytium formation induced by human immunodeficiency virus type 1 isolates correlates with affinity for CD4.

Different strains of human immunodeficiency virus type 1 (HIV-1) show considerable divergence in genetic content and biological properties. One property that has been closely correlated with clinical prognosis is the ability to induce syncytia formation in susceptible cells. This ability had been correlated with the V3 loop sequence of major envelope glycoprotein, gp120, but recent reports have questioned this connection. We investigated the contributions of different regions of the env gene to syncytia induction using chimeric viruses that contain part of the genome of a strain that lacks this ability (HIV-1(Ba-L)) within the genome of a virus that can form syncytia (HIV-1(HXB-2)). When tested in two cell lines susceptible to both parental viruses, as well as in primary cells, these chimeric viruses demonstrated that the ability to induce syncytia formation was determined by regions of env outside the V3 loop, which encompass residues that contribute to the binding of CD4 by gp120. Further investigation failed to show any difference in the expression of gp120 on the cell surface or cell adhesion molecules by cells infected with SI or NSI variants that would explain the observed differences in the ability to form syncytia. Assays of relative affinity for CD4 indicated that gp120 from SI variants showed a significantly higher affinity for CD4 than gp120 from NSI variants. These observations suggest that areas of the HIV-1 env gene contributing to the CD4 binding site may also contribute to the determination of syncytium-inducing (SI) and non-syncytium-inducing (NSI) phenotypes.

Animals↗
PubMed1996

Expression of CD26 does not correlate with the replication of macrophage-tropic strains of HIV-1 in T-cell lines.

Strains of human immunodeficiency virus type 1 (HIV-1) differ significantly in both genetic content and biological properties. One of the earliest discovered differences between HIV-1 strains was divergence in the relative ability of different strains to replicate in either T-cell lines or monocytes/macrophages. This observation has led to the suggestion that molecules present on the surface of HIV-susceptible cells other than CD4 may interact with gp120 in facilitating the entry of HIV-1 into host cell populations. Several reports have suggested that CD26, a cell surface protease expressed on many cells of the immune system including some CD4+ T-cells and macrophage, may be an accessory molecule for HIV-1 entry. Recently, it has also been reported that the expression of high levels of CD26 correlates with the entry and replication of macrophage-tropic strains of HIV-1 in a T-cell line. In this report, we demonstrate that replication of macrophage-tropic strains of HIV-1 in T-cell lines is independent of CD26 expression. From this observation, we conclude that CD26 plays no role in the entry of HIV-1 into these cells.

Animals↗
PubMed1996

Evidence for distinct contributions of heavy and light chains to restriction of antibody recognition of the HIV-1 principal neutralization determinant.

We have used phage Ab display technology to analyze two mAbs to HIV-1 envelope proteins gp120 and gp41. From the data obtained we are able to demonstrate that the recognition of the principal neutralization determinant of different strains of HIV-1 by neutralizing mAb M77 is restricted by its heavy and light chains in different ways. Native M77 is able to recognize and neutralize HIV-1 strain IIIB through binding to the gp120 V3 loop. M77 is unable to recognize strains of HIV-1 that differ on either the left or right side of the V3 loop tip. A chain-switched Fab fragment containing the M77 Fd fragment and a different light chain was able to recognize HIV-1 strains that differ from IIIB on the left side but not the right side of the V3 loop tip.

Amino Acid Sequence↗