Biomedical subjects

R A Shelby

Publications and source records attributed to R A Shelby.

9 recordsLinked to original sources

PubMed2005

Antigenicity of Streptococcus agalactiae extracellular products and vaccine efficacy.

Streptococcus agalactiae is a major bacterial pathogen that is the cause of serious economic losses in many species of freshwater, marine and estuarine fish worldwide. A highly efficacious S. agalactiae vaccine was developed using extracellular products (ECP) and formalin-killed whole cells of S. agalactiae. The vaccine efficacy following storage of S. agalactiae ECP and formalin-killed S. agalactiae cells at 4 degrees C for 1 year was determined. The stored ECP containing S. agalactiae formalin-killed cells failed to prevent morbidity and mortality among the vaccinated fish, and the relative percentage survival was 29. Serum antibody responses of the stored ECP and freshly prepared ECP against soluble whole cell extract of S. agalactiae indicated that significantly less antibody was produced in fish immunized with stored ECP and S. agalactiae cells than in those fish immunized with freshly prepared ECP and S. agalactiae cells at day 31 post-vaccination. Silver staining of sodium dodecyl sulphate-polyacrylamide gels and immunostaining of Western blots with tilapia antiserum to S. agalactiae revealed that predominant 54 and 55 kDa bands were present in the freshly prepared ECP fraction. The 55 kDa band was absent from the stored ECP and new bands below 54 kDa appeared on the Western blot. The results of this study on S. agalactiae ECP provide evidence for a correlation between protection and antibody production to ECP and for the importance of the 55 kDa ECP antigen for vaccine efficacy.

Animals↗

PubMed2004

Immune responses and host protection of channel catfish, Ictalurus punctatus (Rafinesque), against Ichthyophthirius multifiliis after immunization with live theronts and sonicated trophonts.

The humoral immune responses and host protection of channel catfish, Ictalurus punctatus (Rafinesque), against Ichthyophthirius multifiliis (Ich) were determined after immunization with live theronts and sonicated trophonts. Immunizations with live theronts or sonicated trophonts were carried out by both bath immersion and intraperitoneal (i.p.) injection. Cutaneous and serum immunoglobulin (Ig) levels and anti-Ich antibodies were measured 12 and 21 days post-immunization. The level of Ich infection and survival of catfish were determined after theront challenge. Cutaneous and serum anti-Ich antibodies were significantly higher (P < 0.05) in fish immunized with live theronts by immersion or i.p. injection, or with sonicated trophonts administered by i.p. injection, than in fish immunized with sonicated trophonts by immersion, with bovine serum albumin by i.p. injection, or non-immunized controls. Host protection was noted only in fish immunized with live theronts by immersion or i.p. injection or with sonicated trophonts by i.p. injection. There was a positive correlation between higher levels of anti-Ich antibodies and host survival in the immunized fish.

Animals↗

PubMed2003

Development of an immunoassay to measure the humoral immune response of hybrid striped bass Morone chrysops x M. saxatilis.

Hybrid striped bass (HSB) were immunized with bovine serum albumin (BSA) and the specific anti-BSA immunoglobulin (Ig) was affinity purified from the resulting serum by means of an agarose gel-BSA column. The native Ig had an apparent molecular size of 893 KDD, by size exclusion chromatography, and when examined by polyacrylamide gel electrophoresis (PAGE) under denaturing conditions, resolved to heavy (H) and light (L) chains of 76 and 27 KDD, respectively. Affinity purified native HSB Ig was used to immunize a goat which produced specific anti-HSB Ig antibody (Ab). Purified native HSB Ig was also used to produce two murine monoclonal antibodies (mAbs) with specific affinities for H and L chain moieties of the HSB Ig molecule. Both polyclonal and monoclonal antibodies could be used individually in an indirect enzyme-linked immunosorbent assay (ELISA) to measure specific anti-BSA Ig in HSB serum. These antibodies could also be used in combination to measure total Ig in a capture ELISA format. Using both assays, the kinetics of the humoral immune response of HSB was measured for 98 days following two injections of BSA.

Animals↗

PubMed2001

Experimental verification of a negative index of refraction.

We present experimental scattering data at microwave frequencies on a structured metamaterial that exhibits a frequency band where the effective index of refraction (n) is negative. The material consists of a two-dimensional array of repeated unit cells of copper strips and split ring resonators on interlocking strips of standard circuit board material. By measuring the scattering angle of the transmitted beam through a prism fabricated from this material, we determine the effective n, appropriate to Snell's law. These experiments directly confirm the predictions of Maxwell's equations that n is given by the negative square root of epsilon.mu for the frequencies where both the permittivity (epsilon) and the permeability (mu) are negative. Configurations of geometrical optical designs are now possible that could not be realized by positive index materials.

Journal Article↗

PubMed1999

In vitro ruminal disappearance of fumonisin B1 and its effects on in vitro dry matter disappearance.

Fumonisins were produced by inoculating corn with Fusarium moniliforme M-1325 and incubating for 5 w. Fumonisin B1 (FB1) concentration determined by high performance liquid chromatography was 5,087 ppm. Ruminal fluid inoculum obtained from 2 ruminally cannulated steers and tubes containing 0, 50 or 100 ppm of FB1 were incubated in vitro with ruminal fluid and artificial saliva for 72 h in a 39 C oscillating incubator. Supernatant was analyzed for FB1 concentration, and in vitro dry matter disappearance (IVDMD) was calculated in the remaining precipitates. There was minimal degradation of FB1 by ruminal microbes (about 10%) irrespective of concentration of FB1 used when incubated for the 72 h. No differences in IVDMD rates, were found between treatments, and the rates were normal, indicating that microbial efficiency was unaffected by the presence of FB1 at diet concentrations up to 100 ppm.

Animal Feed↗

PubMed1998

Peanut hulls as a litter source for broiler breeder replacement pullets.

Broiler breeder pullets were reared on either peanut hulls or pine shavings to determine effects of litter type on growth performance and litter characteristics. Pullets were reared to 20 wk of age in rooms initially bedded with 8 cm of clean shavings or hulls. Heating and ventilation were standardized in all rooms. Restricted skip-a-day feeding was used to attain recommended growth curves. Water was continuously provided for ad libitum consumption. Litter and environmental variables were measured throughout rearing and 2 wk after pullets were removed from the litter materials. Feed consumption, BW, mortality, and uniformity at 20 wk were not affected by litter type; however, gizzard weights were decreased in pullets reared on hulls. Litter bulk density increased with use and was greater for shavings through 11 wk, but not thereafter. Particle size decreased with use in both litter types. Through 11 wk, there were more particles in the > 4 mm range and less in the < 1.7 mm range with hulls. Litter moisture increased with use but was not affected by litter type. Litter pH was greater in unused shavings, but during and after use was generally greater in hulls. With both litter types, litter and environmental ammonia levels increased to 11 wk then decreased; however, this effect was more pronounced for hulls. Bacteria populations were not affected by litter type; however, greater fungal populations were observed in shavings at 7 and 15 wk. Aflatoxins were detected in unused hulls but not shavings. Because aflatoxin levels decreased during use and Aspergillus flavus and Aspergillus parasiticus populations were not detected in samples collected during use, aflatoxins observed were presumed to have been formed prior to use. Peanut hulls performed similarly to pine shavings as a litter source for breeder pullets; however, the specific influence of the aflatoxins contained in this litter source on bird performance deserves further study.

Aflatoxins↗

PubMed1998

Effects of fumonisin B1-contaminated feeds on weanling angora goats.

Two diets containing no (<1.0 mg/ kg) or 95 mg of fumonisin B1 (FB1)/kg were fed to eight weanling Angora goats for 112 d. Dry matter intake, apparent nutrient digestibilities, serum chemistry profiles, sphingolipid concentrations, and persistency of FB1 in tissues were evaluated. No differences (P>.10) were found between control and treated goats in terms of DMI, apparent nutrient digestibilities, or ADG. Elevated concentrations (P<.10) of blood-borne enzymes such as aspartate aminotransferase, lactate dehydrogenase, and gamma glutamyl transpeptidase and increased concentrations of cholesterol and triglycerides indicated mild liver damage and kidney dysfunction in treated goats. Linear relationships (P<.10) were observed between these serum constituents and duration of FB1 exposure. The sphingolipid analysis of liver, kidney, and heart tissues showed elevated free sphinganine:free sphingosine ratios in the treated group. The elevated sphingolipid ratios were mainly due to increased concentrations of free sphinganine in tissues. However, without serum profile and sphingolipid analyses, fumonisin toxicosis would not have been recognized because treated animals showed no clinical signs of toxicosis throughout the trial. No measurable FB1 was present in liver, kidney, and heart tissues (detection limit of 1 ppm). However, further research is needed to analyze tissues for FB1 or its metabolites with a lower detection limit. In conclusion, goats can be fed for up to 112 d with diets containing 95 mg FB1/kg of diet without any overt signs of toxicosis and also without any effect on live weight gain.

Animal Feed↗

PubMed1994

Influence of endophyte-infected tall fescue on cyclicity, pregnancy rate and early embryonic loss in the mare.

The effects of grazing endophyte-infected tall fescue on luteal function, pregnancy rates, and embryonic loss rates were compared between treated mares (n=18) and untreated controls (endophyte-free, n=12). Mares grazing endophyte-infected fescue demonstrated significantly (P<0.01) prolonged luteal function (22.9 vs 15.8 d) than those grazing endophyte-free fescue. Continuous grazing of endophyte-infected fescue resulted in a decreased (P=0.30) per cycle 14-d viable pregnancy rate (14/31, 45.2%) compared with that of endophyte-free grazing (12/16, 75.0%). Early embryonic death rates were higher (P=0.20) in the endophyte-infected group (6/20, 30.0%) than the endophyte-free group (1/13, 7.7%). Cumulative pregnancy rates after a 60-d breeding period did not differ between the 2 groups. Embryonic development based on mean vesicle height at 14-d was not significantly different between treatment groups for embryos that maintained viability. Embryos that underwent early embryonic death were smaller (P<0.10) at Day-14 than embryos that maintained viability. Mean plasma progesterone concentrations were significantly (P<0.01) greater at Day-21 postovulation in endophyte-infected mares in which the embryo remained viable (15.8 ng/ml) than in endophyte-free mares that experienced early embryonic death (9.8 ng/ml) or that demonstrated prolongation of luteal function (11.2 ng/ml). The results of this study suggest that grazing endophyte-infected tall fescue can have a detrimental effect on reproductive efficiency in the mare due to an increase in cycles bred per pregnancy rate, increased early embryonic death rate and prolongation of luteal function.

Journal Article↗

PubMed1991

Effects of the fungal endophyte Acremonium coenophialum in fescue on pregnant mares and foal viability.

Effects of the endophyte Acremonium coenophialum in tall fescue on pregnant mares and foal viability were evaluated. Twenty-two mature pregnant mares were randomly chosen to graze either Kentucky-31 tall fescue that was free from A coenophialum (endophyte-free, EF) or tall fescue infected with A coenophialum (endophyte-present, EP) after the first 90 days of pregnancy through parturition. Concentrations of pyrrolizidine and ergopeptine alkaloids were significantly greater in EP grass, compared with EF pasture. Ten of 11 mares grazing EP pasture had obvious dystocia. Mean duration of gestation was significantly greater for the EP group, compared with the EF group. Foal survivability was severely reduced among mares grazing EP fescue with only 1 foal surviving the natal period. Udder development and lactation were low in mares grazing EP grass. The absence of clinical problems in mares grazing EF grass implicated the endophyte as the causative agent of reproductive problems and perinatal foal mortality in pregnant mares grazing endophyte-infected fescue grass. Caution should be exercised in allowing pregnant mares to graze pastures infected with the endophyte A coenophialum.

Acremonium↗