Development and usefulness of new polymerase chain reaction-based tests for detection of different alleles at codons 136 and 171 of the ovine prion protein gene.

OBJECTIVE: To develop new and improved tests to detect alleles at codons 136 and 171 of the ovine prion protein locus and to evaluate the frequency of these alleles. ANIMALS: 159 Suffolk sheep belonging to 3 flocks. PROCEDURE: Polymerase chain reaction (PCR) analysis that contained diagnostic restriction site variation for each allele were developed for the relevant gene regions. Alleles were determined by analyzing DNA isolated from buccal swab specimens or blood samples. RESULTS: At codon 136, frequencies of the alanine and valine alleles were found to be 97 and 3%, respectively. At codon 171, frequencies of the glutamine, arginine, and histidine alleles were found to be 57, 41, and 2%, respectively. CONCLUSIONS: Little variation was detected in codon 136, whereas noteworthy variation was found in codon 171; > 40% of the alleles at this locus coded for glutamine. Because the glutamine allele at codon 171 confers susceptibility to scrapie, reduction of its frequency is of importance to management of sheep flocks. CLINICAL RELEVANCE: Genotyping of sheep, using the tests reported here, should facilitate selective breeding programs designed to decrease the risk of scrapie.

Prevalence of leukemic blood and bone marrow in dogs with multicentric lymphoma.

Multicentric lymphoma was diagnosed in 53 dogs. A study was performed to evaluate the prevalence of leukemic involvement in blood samples, bone marrow aspirates, and bone marrow core biopsy specimens at the time of initial diagnosis. Data indicated that 57% (30/53) of the dogs were leukemic when all materials were considered relative to the presence of cellular atypia or immaturity and abnormal tissue distribution. In the 30 leukemic dogs, detection was made in the specimens with the following frequency: 15 in blood (50%), 18 in bone marrow aspirates (60%), and 29 in bone marrow core biopsy specimens (97%). Five cases (17%) were only detected by core biopsy examination, even when dogs with bone marrow lymphocytosis of greater than 15% of nucleated cells were considered leukemic. Nondiffuse histologic colonization patterns accounted for the lack of correlation between the type of bone marrow specimens. Clinical staging for treatment response and prognosis was best determined by evaluation of concurrently obtained blood samples, bone marrow aspirates, and bone marrow core biopsy specimens.

Natural killer cell activity in untreated and treated dogs with lymphoma.

Natural killer (NK) cell activity and function were determined for 11 untreated and treated dogs with lymphoma. Concurrent chromium release and single cell binding assays, methods used to measure overall cytotoxic activity and that from individual cells, respectively, were performed at effector-to-target cell ratios of 50:1 and 100:1, with incubation periods of 12 and 16 hours. Significant reduction was achieved in overall activity for untreated dogs, using a 16-hour incubation period and an effector-to-target ratio of 100:1 (P less than 0.05). Decreased activity (P less than 0.025) was also achieved for those dogs that were administered combination chemotherapy, consisting of such drugs as cyclophosphamide, vincristine, prednisone, and doxorubicin. There was no significant difference in binding or cytotoxic activity by individual cells in the untreated or treated dogs, compared with the healthy controls. Short- or long-term treatment with glucocorticoids did not influence overall NK cll activity or individual cell cytotoxicity. The overall cytotoxic activity in untreated dogs was reduced, but these dogs had relatively normal numbers of NK cells compared with paracontrols. This suggests that a defect in recycling or the ability to kill targets repetitively, may be involved. A similar defect was found in NK cells of dogs treated aggressively with combination chemotherapy.

Histopathology of canine bone marrow in malignant lymphoproliferative disorders.

Bone marrow core biopsies from 63 dogs with malignant lymphoproliferative disorders and leukemic involvement were evaluated. Multicentric lymphoma (44), multiple myeloma (8), chronic lymphocytic leukemia (9), and acute lymphoblastic leukemia (2) were found. Four distinct bone marrow histologic patterns were identified: focal (6), mixed (20), interstitial (28), and packed (9). Of those with focal or mixed patterns, 77% (20/26) had paratrabecular distribution. Stromal changes were infrequent, with 6% (4/63) having necrosis, 3% (2/63) fibrosis, and 6% (4/63) osteolysis. For each condition, the interstitial and mixed patterns were the most common presentations, while focal and packed patterns occurred less frequently. Morphologically, cells of metastatic lesions of lymphoma resembled those of primary sites. Colonization of bone marrow by various cytologic types of lymphoma was independent of the histologic patterns.

Myelodysplastic changes in a cat with myelomonocytic leukemia.

A cat had clinical and pathologic features similar to those of human subacute myelomonocytic leukemia. Studies involved cytologic, histologic, and cytochemical techniques. Findings included macrocytic nonregenerative anemia, monocytosis, thrombocytopenia, hyperproliferative bone marrow, and myelodysplasia typified by hypersegmented neutrophils and micromegakaryocytes.

Canine immunoreactive insulin quantitation using, five commercial radioimmunoassay kits.

Five commercial radioimmunoassay (RIA) kits developed for quantitation of human immunoreactive insulin (IRI) were evaluated for their capability to quantitate canine IRI. Evaluation criteria included precision, dilutional parallelism, sensitivity, and comparison of IRI concentration in 4 control sera. One RIA kit had good dilutional parallelism, consistently good precision, and adequate sensitivity. Other RIA kits had poorer performance in dilutional parallelism or precision. No RIA kit quantitated the same IRI concentrations in all 4 control sera as did another. The results indicated that quantitation of canine IRI by some commercial RIA kits (for human use) may not be reliable. Variations in IRI concentrations quantitated indicated that reference intervals for healthy dogs should be established for each insulin RIA. At least 17 commercial radioimmunoassay (RIA) kits are available to quantitate human immunoreactive insulin (IRI). Two RIA kits have been used to quantitate canine IRI, but validation of assays to quantitate canine IRI were not reported. Evaluation of RIA validity should include assessment of specificity, precision, sensitivity, and accuracy. Two methods are recommended for assessing specificity: (i) demonstration of dilutional parallelism, and (ii) demonstration that related substances do not influence quantitation of analyte. Human insulin differs from canine insulin by having 1 amino acid substitution at the carboxyl-terminal of the B chain. Thus, it is possible that antibodies developed to react with human IRI will have cross immunoreactivity with canine IRI. Precision is affected by a variety of factors including technical steps and antigen-antibody interactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of the pathogenesis of anemia of inflammation: erythrocyte survival.

Erythrocyte survival was investigated in healthy cats and in cats with sterile abscesses. Erythrocyte survival time in cats with sterile abscesses was found to be significantly reduced. The erythrocyte destruction appeared to be the major factor in the early stages of anemia of inflammation.

Studies of the pathogenesis of anemia of inflammation: mechanism of impaired erythropoiesis.

Cats with induced sterile abscesses developed a hematologic disorder consistent with anemia of inflammation. Serum iron concentrations decreased while the abscess was present, but erythropoietin concentrations did not change significantly. Cobalt administration to control (healthy) cats resulted in polycythemia, reticulocytosis, and hyperferremia. Cats with abscesses responded to cobalt similarly; however, magnitudes of the polycythemia and reticulocytosis were less. Constant infusion of ferric citrate (IV) into cats with sterile abscesses maintained serum iron concentration in the normal to high range. The iron infusion did not prevent the anemia, but did enable the bone marrow to respond to the anemia.

Equine ocular onchocerciasis: histopathologic study.

Equine eyes (368) were examined clinically and histologically for abnormalities associated with the presence of ocular microfilariae of naturally occurring Onchocerca sp infection. Forty of the eyes had microfilariae in the conjunctiva, but distinguishing clinical abnormalities were not associated with their presence. In 1 horse with ocular microfilariae that was treated with diethylcarbamazine daily for 2 weeks, ocular tissue samples were obtained before, during, and after the horse was treated, and the samples were compared histologically. During treatment of the horse, microfilariae apparently moved from the conjunctival stroma into the perilimbal corneal stroma; inflammatory cells were more abundant in the perilimbal tissues. The tissue samples obtained before and after the treatment appeared similar.

Equine onchocerciasis: lesions in the nuchal ligament of midwestern U.S. horses.

Nuchal ligaments from midwestern U.S. horses infected with adult Onchocerca sp. were studied. The prevalence of Onchocerca sp. infection in horses increased with age. Ten percent of horses less than one year old were infected, 28% of horses one to five years old, 48% of horses six to 15 years old, and 90% of horses over 16 years old. Lesions in Onchocerca sp.-infected nuchal ligaments varied with age of the horse. Horses less than five years old had few or no lesions, whereas most horses six to 15 years old had focal mineralization and granuloma formation around adult worms. In infected nuchal ligaments of horses over 16 years old, mineralization was much greater and fewer normal parasites were found. Our data suggest that infection by viable parasites is terminated naturally.

Esophageal healing in the pony: comparison of sutured vs nonsutured esophagotomy.

Esophageal healing was evaluated in 10 ponies after sutured and nonsutured cervical esophagotomy techniques. Mucosal healing occurred significantly (P less than 0.005) faster after sutured esophagotomies (x = 7.5 days after surgery) than after nonsutured esophagotomies (x = 25.6 days after surgery), based on endoscopic and clinical evaluations. Although endoscopy was an accurate assessment of the return of normal passage of a food bolus through the esophagus, 4 of 10 ponies had radiographic evidence of a sinus tract after the mucosa was considered healed, based on endoscopic and clinical examinations. The surgical skin wound also healed significantly sooner after sutured esophagotomies (x = 10 days) than after nonsutured esophagotomies (x = 33.4 days). A traction diverticulum developed in all ponies with nonsutured esophagotomies, but occurred in only 1 pony with sutured esophagotomy. Minor complications were seen more frequently with sutured esophagotomy than with a nonsutured esophagotomy, but were resolved with local therapy. Saliva appeared to inhibit wound healing. All ponies were fed through esophagostomy tubes until the mucosa at the esophagotomy site was considered healed. Except for 1 sutured esophagotomy that dehisced, sutured esophagotomy was superior to nonsutured esophagotomy, because earlier establishment of a mucosal seal resulted in more rapid healing and reduced nursing care.

Acid-base and electrolyte alterations associated with salivary loss in the pony.

Esophageal fistulas were made in 6 ponies to evaluate whole blood acid-base values and serum and salivary electrolyte alterations associated with salivary depletion. Acid-base and electrolyte values remained within normal ranges for 15 days in 3 control ponies fed a pelleted diet through nasogastric tubes. In 6 ponies with esophageal fistulas that were fed the same diet through esophagostomy tubes, hypochloremia and hyponatremia developed during the same period. Serum K concentrations were only marginally depleted, probably because of dietary replacement. Salivary depletion resulted in transient metabolic acidosis from bicarbonate lost in saliva followed by progressive metabolic alkalosis. The alkalosis probably resulted from renal compensation of electrolyte imbalances. Salivary electrolytes were in high concentrations, probably because of increased salivary flow rates. Initial saliva was rich in Na, Cl, and K, but progressive reduction in salivary Na and Cl concentrations occurred during the 5-day collection period. These electrolyte savings could be explained by dietary influences and hormonal control of electrolyte transport in salivary ducts. Therapy for correction of acid-base and electrolyte alterations was also discussed.

Subchronic administration of technical pentachlorophenol to lactating dairy cattle: performance, general health, and pathologic changes.

Technical grade pentachlorophenol (penta) was fed subchronically to lactating dairy cattle to establish whether exposure approximating farm environments containing substantial penta-treated wood represents a hazard to animal health. Four Holstein cattle in early lactation were fed .2 mg penta/kg body weight per day for 75 to 84 days followed by 2 mg penta/kg body weight per day for 56 to 60 days. Each treated cow was paired with a control cow of equivalent stage of lactation. Milk production, feed intake, and body weight were not affected by either dose except that treated cattle were more efficient converters of feed to milk during the early stage of the 2 mg/kg period. Neither milk fat production nor somatic cell count in milk were affected by exposure to penta. Postmortem examination revealed enlargement of liver, lungs, kidneys, and adrenals and thickening of the urinary bladder wall. Chronic interstitial nephritis and subacute urocystitis were the major pathologic changes in penta-treated cattle. In vitro testing of kidney slices confirmed significant loss of renal function. The relationship of lesions to administration penta is not clear.

Electron temperatures and densities in the venus ionosphere: pioneer venus orbiter electron temperature probe results.

Altitude profiles of electron temperature and density in the ionosphere of Venus have been obtained by the Pioneer Venus orbiter electron temperatutre probe. Elevated temperatutres observed at times of low solar wind flux exhibit height profiles that are consistent with a model in which less than 5 percent of the solar wind energy is deposited at the ionopause and is conducted downward through an unmagnetized ionosphere to the region below 200 kilomneters where electron cooling to the neutral atmosphere proceeds rapidly. When solar wind fluxes are higher, the electron temperatures and densities are highly structured and the ionopause moves to lower altitudes. The ionopause height in the late afternoon sector observed thus far varies so widely from day to (day that any height variation with solar zenith angle is not apparent in the observations. In the neighborhood of the ionopause, measuremnents of plasma temperatures and densities and magnetic field strength indicate that an induced magnetic barrier plays an important role in the pressure transfer between the solar wind and the ionosphere. The bow, shock is marked by a distinct increase in electron current collected by the instrument, a featutre that provides a convenient identification of the bow shock location.