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Biomedical subjects

K L Smith

Publications and source records attributed to K L Smith.

At least 127 records · Page 7Linked to original sources
PubMed1995

Antigenic crossreactivity and lipopolysaccharide neutralization properties of bovine immunoglobulin G.

We investigated a possible mechanism by which immunization against core and lipid A determinants of lipopolysaccharide reduced clinical cases of mastitis and symptoms commonly associated with heterologous Gram-negative IMI. The IgG fraction of sera from cows immunized with either Escherichia coli J5 bacterin, E. coli J5 lipopolysaccharide conjugate vaccine, or unimmunized controls was purified by precipitation with caprylic acid and ammonium sulfate. The degree of IgG crossreactivity with Gram-negative bacteria that were isolated from clinical quarters was greater than that with Gram-positive isolates of Staphylococcus aureus. The highest magnitude of crossreactivity was against smooth strain E. coli isolates, followed by heterologous species of Enterobacter, Serratia, and Klebsiella isolates. Serum IgG from cows immunized with conjugate was highly crossreactive to E. coli J5, E. coli O111:B4, Serratia marcescens, Klebsiella pneumoniae, and Salmonella typhimurium lipopolysaccharides. The magnitude of antibody crossreactivity with lipopolysaccharides coincided with the ability of IgG to suppress the mitogenic effect of lipopolysaccharides on bovine lymphocytes.

Ammonium Sulfate↗
PubMed1994

Localizing sites of intradendritic electrophysiological recordings by confocal light microscopy.

Studies were undertaken to develop microscopic methods and imaging procedures that would permit identification of sites of intradendritic microelectrode recordings from pyramidal cells in hippocampal slice preparations. Intradendritic recordings were obtained with sharp microelectrodes filled with the dye lucifer yellow. Following a recording session a neuron was iontophoretically injected with the dye and imaged by fluorescence videomicroscopy. Images were stored on videotape for later analysis. They provided a record of the location of the microelectrode recording site. After withdrawal of the microelectrode, slices were processed histologically and imaged a second time with a Bio-Rad 600 confocal attachment on an Olympus BH-2 microscope. Confocal images provided detailed anatomical information in three dimensions. In most instances, a clear identification of the recording site was achieved by comparing video images containing the recording electrode and confocal images. Neurophysiological recordings obtained from proximal and distal apical dendrites were markedly different. Proximal dendritic recordings were similar to those obtained from pyramidal cell soma. However, distal dendrites were not electroresponsive when depolarized by intracellular current injection. The techniques described here, or variations that employ patch electrodes, could provide valuable information that should further an understanding of the properties of dendrites in the central nervous system.

Action Potentials↗
PubMed1994

c-erbB-2 amplification in breast cancer: detection in formalin-fixed, paraffin-embedded tissue by in situ hybridization.

We describe a sensitive and practical in situ hybridization method, using a digoxigenin-labeled probe, for the detection of c-erbB-2 amplification in breast cancer in formalin-fixed, paraffin-embedded tissue sections. Forty-six primary breast carcinomas were studied. Nuclear hybridization signal was observed in 36 of 46 carcinomas. Signal was confined to malignant cells. Normal breast epithelium and stromal and inflammatory cells were uniformally negative. DNase predigestion, no-probe preparations, and competitive hybridization confirmed the specificity of the reaction. The hybridization reaction was localized to multiple discrete foci in tumor cell nuclei, suggesting multiple sites of gene copy and transcriptional activity in the nucleus. Considerable cell-to-cell variation in hybridization signal was evident within individual tumors and positive reactions were observed in several cases in which amplification could not be detected by either Southern or slot blot analysis. The high sensitivity and specificity of the reaction and its use in a tissue-based system will allow the study of a range of possible precursor lesions of breast cancer for evidence of c-erbB-2 amplification.

Breast Neoplasms↗
PubMed1994

Plaster of Paris splintage for the hand: volar or dorsal?

The effectiveness of a volar or a dorsal plaster of Paris slab for splinting a hand in the 'safe' position was studied prospectively. Seventy-two splints, comprising 36 dorsal and 36 volar, were applied. Measurements of the metarcarpophalangeal joint angle and the proximal interphalangeal joint angle on the lateral radiograph revealed the volar splint to be significantly more consistent in securing the proximal interphalangeal joint angle at less than 15 degrees. There was no significant difference between volar or dorsal splints for the metarcarpophalangeal joint angle. As the volar splint was also subjectively more comfortable, its use is recommended.

Calcium Sulfate↗
PubMed1994

Therapy of experimentally induced coliform mastitis with a Propionibacterium acnes product.

The efficacy of a Propionibacterium acnes product for treatment of coliform mastitis was evaluated following intramammary infusion of Escherichia coli. Ten cows were injected intravenously with a product containing heat-killed P. acnes at 3 h, 3 d, and 7 d after bacterial challenge. Five cows served as untreated negative controls. Bacterial counts in milk, rectal temperatures, and milk SCC did not differ between treated cows and control cows. Intravenous infusion of P. acnes had no effect on milk production or DMI of treated cows compared with untreated controls. Therapy of experimentally induced coliform mastitis with a P. acnes product had no effect on severity or duration of clinical signs.

Adjuvants, Immunologic↗
PubMed1994

Effect of dietary fat and vitamin E on alpha-tocopherol and beta-carotene in blood of peripartum cows.

Nonlactating cows were fed diets containing 88% grass forage and 12% concentrate (DM basis). Starting 14 d prior to anticipated calving, the concentrate was changed to provide 0 or 200 g of supplemental fat and 0 or 890 IU of supplemental vitamin E daily. Following parturition, cows were fed for 14 d a 50% concentrate diet that provided the same amounts of supplemental fat and vitamin E that were fed during the dry period. Plasma was sampled and analyzed for alpha-tocopherol and beta-carotene. Supplemental dietary fat elevated plasma concentrations of both nutrients during the peripartum period. Supplemental dietary vitamin E elevated concentrations of alpha-tocopherol during that period. Dietary fat also increased concentrations of plasma cholesterol. When alpha-tocopherol and beta-carotene were expressed per unit of plasma cholesterol, fat supplementation did not affect concentrations. Dietary treatments did not influence concentrations of alpha-tocopherol in blood neutrophils and did not affect intracellular kill of bacteria by neutrophils. Essentially no beta-carotene was found in the neutrophils. For colostrum, dietary vitamin E increased concentrations of alpha-tocopherol and decreased concentrations of beta-carotene.

Animal Feed↗
PubMed1994

Efficacy of dry cow therapy and a Propionibacterium acnes product in herds with low somatic cell count.

Dry cow therapy and a Propionibaterium acnes product were evaluated in four commercial herds with low SCC. Cows were randomly assigned within herds to treatment groups of approximately 90 cows receiving dry cow therapy, P. acnes, dry cow therapy plus P. acnes, or no treatment in a factorial arrangement. Each lactating quarter of cows that received dry cow therapy was infused via the teat duct with 300 mg of cephaprin at drying off. Cows that received P. acnes were infused intravenously with .4 mg of killed P. acnes at drying off, 7 to 10 d prepartum, and within 7 d after calving. A second prepartum injection of P. acnes immunostimulator was administered to cows that did not calve within 10 d after the first prepartum injection. Dry cow therapy enhanced bacteriological cures of IMI by Staphylococcus aureus and Corynebacterium bovis at drying off. Dry cow therapy reduced incidence of new IMI by environmental streptococci and C. bovis that originated during the dry period. Cows treated with P. acnes alone had a greater incidence of new IMI by Gram-negative bacilli originating during the dry period than did cows in the other treatment groups. Incidence of clinical mastitis at calving was greater for cows receiving no treatment than for cows receiving dry cow therapy, P. acnes, or dry cow therapy plus P. acnes.

Adjuvants, Immunologic↗
PubMed1993

Association of abnormal uterine discharge with new intramammary infection in the early postpartum period in multiparous dairy cows.

The association of abnormal uterine discharge with the development of intramammary infection (IMI) was studied in 62 multiparous Holstein cows during the nonlactating period and from lactation days 3 through 30. Duplicate milk samples were obtained from each mammary gland at approximately day 30 of the nonlactating period. Milk samples for bacteriologic culture also were obtained from each gland from all cows at the end of the previous lactation, at parturition, and on a minimum of 7 additional dates during the first 30 days of lactation. Beginning after parturition and continuing once weekly for 4 weeks, each cow was examined, using a vaginal speculum to visually estimate the quantity of abnormal uterine discharge in the vagina. Additionally, uterine swab specimens were obtained for aerobic bacteriologic culture. Cows were allotted to groups on the basis of the maximal amount of abnormal uterine discharge observed at any 1 of the 4 examinations. Cows in group 1 had normal discharge or < 30 ml of abnormal discharge; in group 2, > or = to 30 ml of abnormal discharge, observed only on examination by vaginal speculum; and in group 3, > or = to 30 ml of abnormal discharge visible externally. A difference was not detected in the development of new IMI in the nonlactating period between cows that subsequently developed uterine discharge and those that did not. Although significant differences were not found, a tendency for lactating cows with abnormal uterine discharge to be at increased risk for developing new IMI was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Characteristics of coagulase-negative Staphylococci isolated from bovine intramammary infections.

Coagulase-negative Staphylococci (CNS) isolated from 86 different bovine intramammary infections (IMI) were investigated for their plasmid content, antimicrobial resistance, and infection characteristics. Plasmids were isolated from 30.2% of CNS. Number of plasmid bands ranged from 1 to 5. With the exception of tetracycline resistance, the presence of plasmids was not related to antibiotic resistance. Staphylococcus chromogenes was the CNS most frequently isolated from bovine IMI. Intramammary infections were of long duration (mean = 222 days) and resulted in a low incidence of clinical mastitis (8.1% of IMI). The greatest percentage of IMI (55%) were detected in heifers with 57% of these IMI first detected at calving. A total of 56% of IMI originated during the dry period in second lactation or older cows. The number of plasmid-positive CNS IMI was greater (P < 0.05) in multilactational cows when compared to heifers. The presence of a plasmid-positive CNS had no influence on duration of IMI, origin of IMI, clinical status of the infection, and elimination of IMI.

Animals↗
PubMed1993

Lexical-phonological processing of functors: evidence from fluent aphasia.

The purpose of this study was to investigate how functors are processed at the lexical-phonological level. Four fluent aphasics with impaired ability to fully activate entries in the phonological lexicon, as revealed by their noun production, were asked to repeat and read aloud individual functors. Similarities between their functor and noun production (e.g., level of performance, production of phonological errors) indicated that functors are stored along with content words in the phonological lexicon, and are stored with a similar abstract structure. We also considered whether the sentence-planning system can facilitate the phonological encoding of functors presented in isolation.

Aged↗
PubMed1993

What's new in breast cancer? Molecular perspectives of cancer development and the role of the oncogene c-erbB-2 in prognosis and disease.

The oncogene c-erbB-2 is frequently amplified in human breast carcinoma. The c-erbB-2 gene is present as a single copy in normal cells, and has been mapped to chromosome 17 in the region 17q 12-21.32. c-erbB-2 encodes a transmembrane glycoprotein known as p185. The intracellular component of p185 has tyrosine kinase activity; the extracellular domain has a structure resembling a growth factor receptor. c-erbB-2 amplification, p185 overexpression and levels of transcribed c-erbB-2 specific messenger RNA have been studied in a large number of breast carcinomas using a variety of techniques. In general, overexpression of p185 oncoprotein reflects various levels of DNA amplification, though in some cases amplification can be detected in the absence of overexpression of p185 and similarly overexpression of p185 can be present without detectable levels of c-erbB-2 amplification. This findings suggests that multiple mechanisms may be responsible for overexpression. c-erbB-2 amplification and/or overexpression occurs in almost all cases of high grade duct carcinoma in-situ, but has been reported in only 10%-40% of infiltrating duct carcinoma. c-erbB-2 amplification or overexpression occurs rarely in invasive lobular carcinoma, and has not been detected in ductal or lobular epithelial hyperplasia, or in atypical ductal or atypical lobular hyperplasia. It is generally believed that c-erbB-2 amplification/overexpression is an important independent prognostic indicator in breast carcinoma, identifying a subset of patients with poor prognosis tumours, particularly if axillary node metasases are present. However, many unanswered questions remain regarding c-erbB-2 and its role in breast cancer development and progression. The causes of c-erbB-2 amplification are unknown. There is no evidence of mutations in the human gene which might cause amplification or overexpression. The significance of the differences in levels of c-erbB-2 amplification/overexpression in in-situ duct carcinoma and associated invasive duct carcinoma has not been established. Amplification or overexpression have not been reported in atypical duct hyperplasia, a proposed precursor of duct carcinoma in-situ, yet overexpression occurs almost always in high grade duct carcinoma in-situ. c-erbB-2 may play a critical role in the development of a clonal in-situ, proliferation of high histological grade, yet does not obviously influence the acquisition of an invasive phenotype. We would postulated that this instability in amplification/overexpression is of biological significance, and if better understood may aid in the study of progression of human breast carcinoma.

Blotting, Southern↗
PubMed1993

Environmental mastitis.

Environmental mastitis affects all dairy farms and generally is the major mastitis problem on modern, well managed dairy farms. Control measures effective against contagious pathogens are of little value in controlling of environmental pathogens. Control of environmental mastitis is achieved by reducing exposure of teat ends to environmental pathogens and by maximizing the resistance of the cow to intramammary infection. Significant sources of environmental pathogens are organic bedding materials, manure covered alleyways, and wet or damp areas in barns, exercise lots, or pastures. Milking time hygiene can influence teat-end exposure. In general, exposure is minimized when all areas of the environment are clean, cool, and dry. Resistance is maximized by providing a stress-free environment that minimizes teat-end injury, and by feeding balanced diets sufficient in vitamin E and selenium. Antibiotic therapy during lactation or the dry period is of little value in the control of environmental mastitis in dairy herds, with the exception of preventing environmental streptococcal infection during the early dry period. Effective vaccines may help reduce the impact of environmental mastitis in the near future.

Animals↗
PubMed1993

Increased protein degradation and decreased protein synthesis in skeletal muscle during cancer cachexia.

The effects of progressive cachexia on protein metabolism in skeletal muscle has been investigated in mice bearing the MAC16 adenocarcinoma which produces cachexia with tumour burdens of < 1% of the host weight. Weight loss was accompanied by loss of whole body nitrogen in proportion to the overall loss of body mass. Using L-[4-3H]phenylalanine to label proteins in gastrocnemius muscle, a significant depression (60%) in protein synthesis occurred in animals with a weight loss between 15 and 30% accompanied by an increase in protein degradation, which increased with increasing weight loss between 15 and 30%. Muscle degradation in vitro could be achieved by serum from cachectic animals, which appeared to contain a proteolysis-inducing factor. These results suggest that the increased degradation of skeletal muscle seen in this model of cachexia may be due to a circulating proteolysis-inducing factor.

Animals↗
PubMed1993

Mechanism of muscle protein degradation in cancer cachexia.

Depletion of skeletal muscle mass in animals bearing an experimental model of cachexia, the MAC16 adenocarcinoma, occurs by a reduction in protein synthesis accompanied by a large increase in protein degradation. Serum from mice bearing the MAC16 tumour produced an increased protein degradation in isolated gastrocnemius muscle, as measured by tyrosine release, with a maximal effect occurring with serum from animals with a weight loss of between 11 and 20%. The response was specific to the cachectic state, since serum from mice bearing the MAC13 adenocarcinoma, which does not produce weight loss, did not increase tyrosine release from gastrocnemius muscle above that observed with serum from non tumour-bearing animals. The circulatory proteolysis-inducing factor was stable to heating at 60 degrees C for 5 min and was not inhibited by phenylmethylsulfonyl fluoride, suggesting that it was not a serine protease. The level of prostaglandin E2 (PGE2) in gastrocnemius muscle was significantly elevated after incubation with serum from cachectic mice bearing the MAC16 tumour. Both indomethacin and the polyunsaturated fatty acid eicosapentaenoic acid (EPA) inhibited the rise in muscle PGE2 content in response to serum from cachectic mice and also inhibited muscle protein degradation. These results suggest that muscle protein degradation in cancer cachexia is associated with a rise in PGE2 content.

Adenocarcinoma↗
PubMed1993

Detection of cytomegalovirus in blood donors by the polymerase chain reaction.

A polymerase chain reaction (PCR) assay was developed and optimized to detect cytomegalovirus (CMV) DNA in the blood of 86 normal donors who had originally tested seropositive for CMV. Evidence of previous or current infection with CMV was determined by rescreening of the blood for CMV antibodies and by detecting the presence of infectious virus in the white cells by cell culture. DNA was extracted from the blood of donors by a manual or an automated method and amplified by PCR using primers from the major immediate early gene of CMV DNA. The amplified product was detected by visualization of a fluorescent 435-base pair DNA band in an electrophoretic agarose gel after ethidium bromide staining and confirmed by slot-blot DNA hybridization using an oligonucleotide probe with complementarity for the major immediate early gene. Seven (8%) of the 86 donors were positive for CMV DNA in both fluorescence and hybridization studies. These donors were also antibody positive. While 74 (86%) of the 86 donors were positive for the presence of CMV antibodies in enzyme-linked immunosorbent assay, none was positive for virus in cell culture. PCR has the potential to be an effective and reliable procedure for the detection of CMV DNA in donor blood, but further study is required for this technique to be used for diagnostic or routine screening purposes.

Adult↗
PubMed1993

Botulinum B toxin as an alternative to botulinum A toxin: a histologic study.

Histochemical effects of botulinum B toxin were studied on fibers from longissimus dorsi muscle in Albino rabbits and compared to effects produced by botulinum A toxin. Acetylcholinesterase staining, muscle fiber size analysis, and ATPase staining indicated botulinum B toxin produced a denervation gradient and field similar to that produced by botulinum A toxin. At 5 weeks postinjection with botulinum B toxin, analysis showed muscle fiber size variability, and diffuse acetylcholinesterase fiber staining comparable to botulinum A toxin at the injection site. Muscle sections taken at 4.0 cm for analysis showed statistically significant decreased fiber size variability and contraction of acetylcholinesterase staining pattern for both immunotypes. In addition, the denervation reflected by histochemical staining and fiber size analysis appeared transient and lasted for approximately 3 months for both immunotypes. These findings suggest botulinum B toxin produces pharmacologic effects on innervation of striated muscle similar to botulinum A toxin. Because immunologic tolerance has been demonstrated after therapeutic botulinum A toxin injections, further clinical studies need to be conducted with other immunotypes of toxin with no cross-reactivity to type A.

Acetylcholinesterase↗