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Biomedical subjects

R L Walker

Publications and source records attributed to R L Walker.

At least 73 records · Page 4Linked to original sources
PubMed1989

Shared flagellar epitopes of Borrelia burgdorferi and Borrelia anserina.

Antigenic cross-reactivity between Borrelia burgdorferi and Borrelia anserina was studied using mouse immune sera and monoclonal antibodies. With immune sera, significant cross-reactivity between B. burgdorferi and B. anserina was demonstrated by indirect immunofluorescent assay. In immunoblots, most of the cross-reactivity was shown to be associated with the periplasmic flagella. Using monoclonal antibodies in immunoblots, it was shown that B. burgdorferi and B. anserina shared at least two flagellar epitopes, one of which was not shared with Borrelia hermsii or Borrelia coriaceae. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles of whole cell lysates and the use of a species-specific monoclonal antibody (H5332) which reacts with a major outer surface protein (Osp A) of B. burgdorferi readily differentiated the two species at the molecular level.

Animals↗
PubMed1988

Cryptosporidiosis in veterinary students.

Cryptosporidiosis was diagnosed in 10 veterinary students. Exposure to the pathogen was associated with direct contact with infected calves and contact with contaminated materials. Affected students had fever (50%), headache (50%), nausea (70%), diarrhea (80%), and vomiting (40%). Clinical signs persisted for 30 hours to 16 days after the onset of clinical signs of disease. Although one student required hospitalization, the remaining students recovered without treatment.

Animals↗
PubMed1988

Sources of Prototheca spp in a dairy herd environment.

A source of Prototheca spp causing mastitis in a herd of 263 milking cows in North Carolina was investigated. Of 38 samples from the dairy environment, 18 (47%) contained Prototheca spp. Isolation sites included cattle drinking water; a feed trough; mud, dirt, and excreted feces from a dirt lounging area; water, sludge, mud, and vegetation from a creek in the lounging area; and the floor of a freestall barn. Samples were collected from 5 additional dairies, including one dairy with and 4 dairies without a history of protothecal mastitis. Prototheca spp were isolated from 48 (25%) of 190 samples from various sites on all 6 dairies. Isolates were P zopfii (45; 94%) and P wickerhamii (3; 6%). Isolation frequency ranged from 4 to 47% of samples/dairy. There was no apparent difference in the isolation frequency of Prototheca spp from samples from dairies with or without a history of protothecal mastitis. Sites characterized by wetness and the presence of organic matter most commonly yielded Prototheca spp. Because Prototheca spp appear to be common in the dairy environment, factors in addition to presence in the environment may be important in development of protothecal mastitis.

Animals↗
PubMed1988

Eumycotic mycetoma caused by Pseudallescheria boydii in the abdominal cavity of a dog.

An abdominal eumycotic mycetoma with multiorgan dissemination was diagnosed in a 2-year-old dog. Clinical signs included fever, vomiting, diarrhea, weight loss, and a palpable abdominal mass. The dog developed disseminated intravascular coagulation and died. Pseudallescheria boydii was isolated from the abdominal mass, liver, and peritoneal fluid. Relevant history included an ovariohysterectomy when the dog was 6 months old, which was complicated by dehiscence of the incision site and evisceration. It appears that P boydii has a propensity for establishing itself in the abdominal cavity of the dog, subsequent to surgical dehiscence.

Abdomen↗
PubMed1988

Heterogeneity in immunoblot patterns obtained by using four strains of Borrelia burgdorferi and sera from naturally exposed dogs.

This study evaluated the differences in immunoblot patterns when serum specimens from seropositive dogs were reacted against four strains of Borrelia burgdorferi. Intense bands were consistently detected for the 83-, 66-, 61- to 60-, 41-, and 31-kilodalton regions for all four strains. Most variations were observed in the regions of 45 to 34 and 26 to 15 kilodaltons. Adsorption studies suggested that one reason for the observed variability was a difference in proteins among the organisms, rather than a difference in migration of proteins. Therefore, knowledge and consistency of the test antigen are essential when evaluating and comparing canine immunoblot patterns to B. burgdorferi, but for diagnostic purposes all of the serum samples would have been considered positive regardless of the strain used.

Animals↗
PubMed1988

Immunoblot analysis of immunoglobulin G response to the Lyme disease agent (Borrelia burgdorferi) in experimentally and naturally exposed dogs.

Immunoblots were used to study the immunoglobulin G response to Borrelia burgdorferi in experimentally and naturally exposed dogs. Adsorption studies confirmed that the antibodies were specific for B. burgdorferi. Experimentally exposed dogs were asymptomatic. Naturally exposed dogs included both asymptomatic animals and animals showing signs compatible with Lyme disease. Naturally exposed dogs were from four geographic regions of the country. No differences were detected between immunoblot patterns of naturally exposed symptomatic or asymptomatic dogs from different areas of the country. The immunoblot patterns obtained with sera from experimentally exposed dogs were different from those obtained with sera from naturally exposed dogs and were characterized by reactivity to fewer and different protein bands. Immunoblot analysis using an OspA-protein-producing Escherichia coli recombinant showed that experimentally exposed dogs produced antibodies to OspA, whereas naturally exposed dogs did not. Modifications of the immune response over time, different routes of antigen presentation, and strain variation are factors postulated to account for the observed differences.

Animals↗
PubMed1988

Clinical and serologic evaluations of induced Borrelia burgdorferi infection in dogs.

Adult Beagles were used to evaluate clinical signs and serologic response after inoculation with, or exposure to, Borrelia burgdorferi. An indirect immunofluorescent assay (IFA) and 2 ELISA were used to monitor the serologic response to B burgdorferi. Feeding infected ticks on 4 dogs (group 1) failed to cause seroconversion, and SC inoculation with 500 organisms caused minimal seroconversion in 2 of 4 dogs (group 2). At 56 days, approximately 3.01 X 10(8) B burgdorferi organisms were injected IV into group-1 dogs, and intraperitoneally into group-2 dogs. A control group of 4 dogs (group 3) had noninfected ticks feed on them, and then were given IV injection of physiologic saline solution. Increases in immunoglobulin M (IgM) titers were detected in 2 of 4 group-2 dogs approximately 7 days after the initial exposure. These titers returned to negligible values 20 days later. Immunoglobulin G titers increased approximately 10 days after the initial exposure and were mildly increased 56 days later, when dogs were exposed a second time. Both the IV and intraperitoneal injections (second exposures) resulted in increased IgM titers, which in both groups eventually returned to preexposure values after approximately 2 months. Immunoglobulin G titers increased within a week after the second exposure, and in 3 dogs monitored for 8 months, returned to negligible values after the 8-month period. One control dog had a slightly increased IgG titer 24 days after the second inoculation. The possibility of urine transmission is suggested. Clinical status, hemograms, serum biochemical profiles, ECG and results of urinalyses remained normal throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Serodiagnosis of Histophilus ovis-associated epididymitis in rams.

An ELISA for the detection of antibodies to Histophilus ovis was used to evaluate the association of epididymal lesions in rams with serologic response to His ovis. Comparison of ELISA results for His ovis in groups of rams with epididymal lesions with ELISA results of clinically normal rams (control group) revealed a significant difference (P less than 0.01) between the control group and those rams from which His ovis was isolated. A significant difference (P less than 0.01) was noticed between the control group and rams with lesions from which an organism other than His ovis or Brucella ovis was isolated. Additionally, a significant difference (P less than 0.01) was noticed in ELISA results between the control group and affected rams from which no organism was recovered and in which the epididymal lesion was not limited to the head of the epididymis. A difference was not detected in the His ovis ELISA results between control rams and rams with lesions associated with a B ovis infection or rams from which no organism was recovered and in which the epididymal lesion was limited to the head of the epididymis. The serologic findings in our study suggest that His ovis is more important in the development of epididymitis in rams than culture results alone would indicate.

Animals↗
PubMed1987

Guaifenesin alone or in combination with ketamine or sodium pentobarbital as an anesthetic in rabbits.

Guaifenesin was administered alone and in combination with ketamine or sodium pentobarbital to adult New Zealand white rabbits. A solution of 5% guaifenesin in 5% dextrose given intravenously at a dosage of 200 mg/kg, abolished the pedal, palpebral and corneal reflexes for up to 15 minutes with little influence on cardiopulmonary function. Guaifenesin (200 mg/kg, intravenously) and ketamine (50 mg/kg, intramuscularly) produced effective and safe surgical anesthesia for over 30 minutes. This combination mildly depressed respiratory rate but heart rate and arterial blood pressure were not significantly affected. Guaifenesin (200 mg/kg, intravenously) was combined with sodium pentobarbital (20 mg/kg, intravenously) to produce surgical anesthesia for a period of more than 30 minutes. This combination depressed respiratory rate, produced a tachycardia and decreased arterial blood pressure.

Anesthesia, Intravenous↗
PubMed1986

Association of age of ram with distribution of epididymal lesions and etiologic agent.

A 2-year study of the frequency of isolation of various organisms from mature and yearling rams with epididymitis was conducted at the US Sheep Experiment Station at Dubois, Idaho. Investigation into the distribution of lesions in the epididymis in relation to age of the ram also was studied. Serologic or bacteriologic evidence of Brucella ovis infection was demonstrated in 79.5% of the mature rams with epididymal lesions. Actinobacillus seminis and Histophilus ovis were the 2 most frequently isolated organisms from yearling rams with lesions. The tail(s) of the epididymis was the most frequent site of lesion development in the mature rams (86.4%). Yearling rams developed lesions twice as frequently in the tail(s) of the epididymis as in the head(s) of the epididymis. When lesions were localized in the head(s) of the epididymis, an etiologic agent usually was not demonstrated.

Actinobacillus↗
PubMed1986

Mixed germ cell tumor of the ovary with pure choriocarcinoma metastasis.

A case report of a 30-month disease-free survival in a ten-year-old girl with ovarian mixed germ cell tumor consisting of dysgerminoma, choriocarcinoma, and immature teratoma with pure choriocarcinoma paraaortic lymph node metastasis is presented. To prevent resistant cell colonies, the noncross-resistant combination of vinblastine-Adriamycin and vinblastine-actinomycin D-cytoxan were added to the initial four courses of vinblastine-cisplatin-bleomycin. There are no previously reported survivals in ovarian mixed germ cell tumors with pure choriocarcinoma metastasis.

Child↗
PubMed1986

Prevalence of Histophilus ovis and Actinobacillus seminis in the genital tract of sheep.

Histophilus ovis and Actinobacillus seminis were isolated from the preputial cavity of 6-month-old rams and the vagina of 6-month-old ewes at a substantially higher rate than that in mature (greater than 2 years old) rams and ewes. These organisms appeared to be a transitory component of the ovine genital flora, the prevalence of which was associated with age regardless of gender. Additional evaluation of the recoverability of H ovis and A seminis from the preputial cavity of rams from birth to 1 year of age indicated that the isolation rate from rams and predominance of the organisms in the preputial cavity differed greatly over this age period. These organisms were not recoverable until ram lambs were 12 weeks of age and were most prevalent at 20 weeks of age, after which recoverability of H ovis and A seminis from the preputial cavity steadily decreased, continuing through the time of the last evaluation at 1 year of age. The time period with which these organisms can be isolated from the preputial cavity is closely correlated with the time period when epididymitis associated with these organisms develops, and may be an important factor in the pathogenesis of epididymitis.

Actinobacillus↗
PubMed1985

Use of enzyme-linked immunosorbent assay for detection of antibodies to Brucella ovis in sheep: field trial.

An enzyme-linked immunosorbent assay (ELISA), using an autoclave-extracted soluble antigen, for the detection of serum antibodies to Brucella ovis in sheep was developed. The test seemed to be both sensitive and specific, on the basis of the control groups studied. The antigen showed no deterioration in prepared plates stored at -70 C for up to a year. The ELISA was used in conjunction with palpation of rams for epididymal lesions as a means to detect and control B ovis infection in a naturally infected flock. All rams were evaluated by the ELISA. At the time that the first blood sample was obtained, all positive and suspicious reactors were removed. With subsequent blood sample collections, only the positive reactors were removed. Brucella ovis was not isolated from any rams during the following year, and none of the mature breeding rams developed epididymal lesions.

Animals↗
PubMed1982

H+ excretion in the marine teleost Parophrys vetulus.

This study examined the branchial, renal and blood acid-base responses of a marine teleost to intravascular infusion of mineral acid (HCl at 1000 mu-equiv/kg). In all animals the renal response was insignificant for at least 3 days following infusion. Two types of branchial and blood acid-base response were seen. Either the infused load disappeared rapidly from the extracellular into the intracellular compartment and was slowly cleared from the body (+ 16 h following infusion) or, more commonly, remained in the extracellular compartment until rapidly cleared by a pronounced increase in branchial excretion. In the latter the amount excreted exceeded that infused by about twofold on average. These responses are discussed in relation to those of freshwater teleosts.

Acid-Base Equilibrium↗