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Biomedical subjects

R D Walker

Publications and source records attributed to R D Walker.

At least 127 records · Page 7Linked to original sources
PubMed1989

Neutrophil oxidative metabolism after exposure to bacterial phospholipase C.

The effects of phospholipase C (PLC) from Clostridium perfringens and Bacillus cereus on bovine neutrophil oxidative metabolism were studied by measuring superoxide production and oxygen consumption in response to PLC alone or in combination with other stimuli. PLC from both species elicited superoxide production and enhanced the response to stimulation by NaF when the two stimuli were given simultaneously. However, oxygen consumption in response to latex beads was markedly inhibited by pretreatment of cells with B. cereus PLC. The results suggest that some bacterial PLC exoenzymes may initially activate neutrophils but leave the cells relatively unresponsive to subsequent stimuli.

Animals↗
PubMed1989

Transmission of a vaccinal strain of infectious bovine rhinotracheitis virus from intranasally vaccinated steers commingled with nonvaccinated steers.

Ninety-seven feeder steers, averaging 7 months of age, were allotted to 3 groups. Group I (n = 33) was vaccinated intranasally with an infectious bovine rhinotracheitis virus (IBRV) vaccine on postinoculation day (PID) 0; group II (n = 31) was not vaccinated on PID 0 but was commingled with group I; and group III (n = 33) served as controls housed in the same facility, but was physically separated from groups I and II. On PID 20, all steers were given a modified-live IBRV vaccine IM. Virus isolation attempts from nasal swab specimens collected on PID 10 resulted in IBRV isolation from 19 (57.6%) of group I, 4 (12.9%) of group II, and 0 of group III. By PID 20, geometric mean titer for serum antibody to IBRV had increased in group I but had decreased in groups II and III. By PID 40, geometric mean titer for serum antibody to IBRV had increased in the 3 groups in response to IM vaccination given on PID 20. Seemingly, transmission of a vaccinal strain of IBRV to nonvaccinated steers did not take place at a frequency that elicited a humoral immune response similar to that of vaccinated steers.

Animals↗
PubMed1989

Induction of pulmonary antibodies to Pasteurella haemolytica following intraduodenal stimulation of the gut-associated lymphatic tissue in cattle.

The induction of pulmonary antibodies to a bacterial antigen following intraduodenal (D) stimulation of the gut-associated lymphatic tissue (GALT) was investigated. Six calves were divided into two groups of three calves each. The GALT-primed calves received an ID dose of live Pasteurella haemolytica A1 followed by a subcutaneous (SC) dose of killed P. haemolytica. The sham-primed calves received an ID dose of phosphate-buffered saline solution (PBSS) followed by a SC dose of killed bacteria. Serum and pulmonary lavage fluids were collected weekly from each calf and assayed for titers of leukotoxin neutralizing antibodies (LNA), as well as IgG and IgA (lavage fluids only) to P. haemolytica. The GALT-primed calves responded to the ID stimulation by bacteria with increased serum IgG. The sham-primed calves had no change in antibody titers following ID stimulation. The GALT-primed calves had increased serum IgG, lavage IgG and IgA and increased LNA titers in both lavage fluids and serum following the SC dose of killed bacteria. The sham-primed calves demonstrated only an increase in serum IgG following the SC inoculation. A challenge study to evaluate if antibodies induced by GALT stimulation could reduce pulmonary lesions was performed using six calves divided into two groups. One group received an ID dose of P. haemolytica followed two weeks later by a SC dose of killed P. haemolytica. The sham vaccinated calves received an ID dose of PBSS followed in two weeks by a SC dose of killed bacterin. Calves were challenged by an intrapulmonary dose of live P. haemolytica A1 eleven days after the SC inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Serum and tissue fluid norfloxacin concentrations after oral administration of the drug to healthy dogs.

Norfloxacin, a 4-quinolone antibiotic, was administered orally to 4 healthy dogs at dosages of 11 and 22 mg/kg of body weight, every 12 hours for 4 days, with a 4-week interval between dosing regimens. Serum and tissue cage fluid (TCF) norfloxacin concentrations were measured at 0, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 10, and 12 hours after the first and seventh dose of each dosing regimen. When administered at a dosage of 11 mg/kg, the mean peak serum concentration (Cmax) was 1.0 microgram/ml at 1 hour, the time of mean peak concentration (Tmax) after the first dose. After the seventh dose, the Cmax was 1.4 micrograms/ml at Tmax of 1.5 hours. The Tmax for the TCF concentration was 5 hours, with Cmax of 0.3 microgram/ml and 0.7 microgram/ml after the first and seventh dose, respectively. When administered at a dosage of 22 mg/kg, the serum Tmax was 2 hours after the first dose, with Cmax of 2.8 micrograms/ml. After the seventh dose, the serum Tmax was 1.5 hours, with Cmax of 2.8 micrograms/ml. The Tmax for the TCF concentration was 5 hours after the first and seventh doses, with Cmax of 1.2 micrograms/ml and 1.6 micrograms/ml, respectively. After the seventh dose, the serum elimination half-life was 6.3 hours for a dosage of 11 mg/kg and was 6.7 hours for a dosage of 22 mg/kg. For serum concentration, the area under the curve from 0 to 12 hours (AUC0----12) was 8.77 micrograms.h/ml and 18.27 micrograms.h/ml for dosages of 11 mg/kg and 22 mg/kg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1988

Intramuscular injection techniques and the development of clostridial myositis or cellulitis in horses.

A survey of 584 veterinarians in equine practice was performed to determine their intramuscular injection techniques and the influence of those techniques on the development of clostridial myositis or cellulitis. Usable responses were obtained from 439 veterinarians (75.2%). Of these, 414 used a new needle and syringe for each injection, 241 swabbed the site with a cleansing/disinfectant agent, and 242 swabbed the top of multidose injection bottles with a similar solution. Only 2 clipped the hair at the injection site. Twenty eight of the respondents reported that at least 1 horse developed a clostridial infection at the injection site following 1 of their injections. None of the various injection techniques had a significant influence on the development of clostridial infection at the injection site.

Animals↗
PubMed1988

Periurethral polytetrafluoroethylene injection following urethral reconstruction in female patients with urinary incontinence.

We present our results with periurethral polytetrafluoroethylene (Polytef) injection after urethral reconstruction in 20 female patients with urinary incontinence. These patients have failed previous urethral reconstructive procedures to cure incontinence, including Young-Dees-Leadbetter bladder neck reconstruction, transvaginal urethroplasty, transvaginal urethral plication and vesical flap urethroplasty. Of the patients 4 also underwent a bladder augmentation procedure. After polytetrafluorethylene injection 10 patients (50 per cent) were cured of the incontinence, 2 (10 per cent) had marked improvement from the preoperative condition, 5 (25 per cent) had definite improvement but still wear pads for protection and 3 (15 per cent) had no change from the preoperative condition. Bladder pressure recordings did not demonstrate a difference in results among patients with detrusor stability or instability. Periurethral polytetrafluoroethylene injection remains a valuable procedure in the management of persistent incontinence after bladder neck and urethral reconstruction.

Adult↗
PubMed1988

Fractional excretion of magnesium and renal concentrating capacity in refluxing renal units.

To evaluate renal function in kidney units exposed to vesicoureteral reflux we quantified the fractional renal excretion of magnesium and the maximal renal concentrating capacity in 22 renal units of infants and children who presented with grade III to V vesicoureteral reflux on standard voiding cystourethrography. The lowest normal value for maximal concentrating capacity and the highest normal value for fractional excretion of magnesium were set at 800 mOsm. per kg. and 8 per cent, respectively. Concentrating capacity was abnormal in all 22 renal units and the excretion of magnesium was abnormal in 5. Failure of a renal unit to retain magnesium normally was always associated with an inability to concentrate urine. We conclude that in cases of vesicoureteral reflux function of the distal part of the nephron is the first to become abnormal and concentrating capacity is a more sensitive indication of dysfunction than fractional excretion of magnesium.

Adolescent↗
PubMed1988

Pulmonary lesions induced by Pasteurella haemolytica in neutrophil sufficient and neutrophil deficient calves.

The role of neutrophils in the development of peracute lung lesions of bovine pneumonic pasteurellosis was investigated. Eight calves were divided into two groups of four calves each. Group I was treated with intravenous phosphate-buffered saline and served as the neutrophil sufficient calves. Group II was treated with intravenous hydroxyurea which produced a state of neutropenia. When peripheral blood neutrophil numbers dropped below 300 cells/microL in group II, all calves were challenged with an intrabronchial bolus of Pasteurella haemolytica in the log phase of growth. An acute inflammatory process occurred in both groups of calves indicated by a rise in body temperature. While pulmonary lesions occurred in both groups by six hours postinoculation, they varied in pathological characteristics. Pulmonary lesions in the neutrophil sufficient calves consisted of fibrinopurulent alveolitis-bronchiolitis with associated alveolar septal necrosis, interlobular edema, and intravascular thrombi. The neutrophil deficient calves had extensive intra-alveolar edema, interlobular edema, intraalveolar hemorrhage, atelectasis, and focal areas of alveolar septal necrosis. These results show that P. haemolytica can induce severe pulmonary tissue damage through both neutrophil dependent and neutrophil independent mechanisms.

Agranulocytosis↗
PubMed1987

Initial experience with extracorporeal shock wave lithotripsy in children.

The clinical experience is presented of 4 United States centers at which extracorporeal shock wave lithotripsy was used for the treatment of renal calculi in 38 children 12 months to 16 years old. Patient characteristics, treatment specifics and followup data are detailed. Complete fragmentation of calculi was obtained in 97 per cent of those treated, with a 5 per cent complication rate. This experience demonstrates that with proper safeguards, extracorporeal shock wave lithotripsy can be performed safely and effectively in the pediatric population.

Adolescent↗
PubMed1987

Gastrointestinal zoonoses.

Infectious gastrointestinal diseases affect man and animals throughout the world. Certain etiologic agents (for example, Salmonella spp., Campylobacter jejuni, Yersinia enterocolitica, Cryptosporidia, Strongyloides stercoralis, Echinococcus granulosa) seem to have the potential to be transmitted from pets to people, causing severe disease in the latter. Other agents seem unlikely to be transmitted but may have the potential to be zoonoses. This article discusses proved, suspected, and possible zoonotic agents that may originate from the gastrointestinal tract of dogs and cats.

Animals↗
PubMed1987

Psychiatric assessment and treatment of American Indians and Alaska Natives.

It is widely recognized that the cultural uniqueness of American Indians and Alaska Natives must be reflected in the methods of diagnosing and treating their mental health problems, but empirical validation of specific diagnostic instruments and treatment has been slow in coming. The authors' literature review indicates that many standardized self-rating scales and interview schedules can accurately assess mental illness among Indians, provided they are modified to reflect cultural heritage and experiences. Group therapy is increasingly chosen as a psychiatric treatment for American Indians, as are family-network therapy and several traditional Indian therapies. The authors also review the demographics and psychiatric epidemiology of American Indians and Alaska Natives.

Alaska↗
PubMed1987

Experimental infection of lactating bovine mammary glands with Streptococcus uberis in quarters colonized by Corynebacterium bovis.

Twenty-seven quarters of 18 lactating dairy cows were inoculated intramammarily with 3.6 X 10(4) colony-forming units (CFU) of a strain of Streptococcus uberis isolated from a cow with clinical mastitis. Before quarters were inoculated, 22 were considered as naturally colonized with Corynebacterium bovis, and 5 were considered bacteriologically negative. Streptococcus uberis was isolated from all quarters within 2 days after inoculation, and all quarters developed clinical mastitis by 3 days after inoculation. Mastitis was acute, and most cows had increased rectal temperatures. The number of somatic cells increased significantly (P less than 0.05), and milk production decreased significantly. In many cows, rectal temperatures remained increased, and Str uberis was isolated from infected glands after intramammary and systemic antimicrobial treatments were given. A decreased number (110 CFU) of the same strain of Str uberis caused equally severe mastitis in 3 quarters colonized with C bovis and in 1 bacteriologically negative quarter in 2 cows. Streptococcus uberis was isolated from all inoculated quarters, and all quarters developed clinical mastitis by 2 days after inoculation. Two quarters colonized with C bovis and 2 bacteriologically negative quarters were inoculated once with 25 CFU and once with 240 CFU of a different strain of Str uberis (ATCC 27958). Streptococcus uberis was never isolated from inoculated quarters, and changes in milk yield or number of somatic cells were not observed.

Animals↗
PubMed1986

Alcoholic subtypes based on multiple assessment domains. Validation against treatment outcome.

Research in the area of subtype development within alcoholic populations has undergone a number of changes over the recent years. First, there has been a shift from subtype derivation based on a priori comparative approaches toward a more recent use of a posteriori correlational approaches such as cluster analysis. Second, there has been an increased multivariate focus in which multiple measures from a number of practically and/or theoretically relevant assessment domains are entered into the classificatory process. Third, there has been an increased emphasis on the external validation of derived clusters. The present chapter briefly reviews these issues, using examples of research from the Seattle Veterans Administration Medical Center to illustrate each of these shifts across a series of studies focusing on the development of alcoholic subtypes. Finally, the results of a recent subtype identification and validation study will be presented to illustrate the difficulties in and advantages of a multidomain cluster analytic strategy.

Adult↗
PubMed1986

Statistical analysis of statural growth following kidney transplantation.

Factors affecting the growth rates of 59 children and adolescents for the first 2 years following kidney transplantation were evaluated. The factors assessed were age at transplantation, renal function, prednisone dosage, donor source, and prior history of transplantation. The observed growth velocity was expressed as the percentage, of the growth velocity predicted by bone age. Normal growth (greater than or equal to 80%) was exhibited by 37% of the patients and 22% had accelerated growth (greater than or equal to 100%). The chronologic age at transplantation did not correlate significantly with growth when bone age was used as the reference for expected velocity. Males grew better than did females. There was a unique sex/race interaction with black males growing most rapidly. Better renal function, the ability to lower prednisone dosage, alternate day prednisone administration, and a decreasing diastolic blood pressure were positively correlated with better growth rates after transplantation. The donor source and prior history of transplantation did not significantly influence growth rate.

Adolescent↗
PubMed1986

Statistical analysis of statural growth following kidney transplantation.

Factors affecting the growth rates of 59 children and adolescents for the first 2 years following kidney transplantation were evaluated. The factors assessed were age at transplantation, renal function, prednisone dosage, donor source, and prior history of transplantation. The observed growth velocity was expressed as the percentage of the growth velocity predicted by bone age. Normal growth (greater than or equal to 80%) was exhibited by 37% of the patients and 22% had accelerated growth (greater than or equal to 100%). The chronological age at transplantation did not correlate significantly with growth when bone age was used as the reference for expected velocity. Males grew better than did females. There was a unique sex/race interaction with black males growing most rapidly. Better renal function, the ability to lower prednisone dosage, alternate day prednisone, and a decreasing diastolic blood pressure were positively correlated with better growth rates after transplantation. Donor source and prior history of transplantation did not significantly influence growth rate.

Adolescent↗
PubMed1986

Transitional cell papilloma of the bladder.

Bladder tumors of epithelial origin are rare in children. A 7-year-old male presented with intermittent painless hematuria. An ultrasound examination of the bladder revealed a single polypoid mass which proved to be a transitional cell papilloma.

Adolescent↗