Parenterally administered kainic acid induces a persistent hyperalgesia in the mouse and rat.

Nociceptive primary afferent C-fibers express a subset of glutamate receptors that are sensitive to kainic acid. Thus, we tested the possibility that activation of these receptors alters nociception. Intraperitoneal (i.p.) injection of kainic acid induced a persistent thermal hyperalgesia, when tested using the hot plate (mice) and tail flick (mice and rats) assays, and mechanical hyperalgesia when tested using von Frey monofilaments (rats), but had no effect on acetic acid-induced chemical nociception (mice). When administered i. p., 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), an (R, S)-alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid HBr/kainate (AMPA/KA) antagonist, completely blocked hyperalgesia. When injected intrathecally (i.t.), kainic acid itself failed to induce hyperalgesia and AMPA/KA antagonists given i.t. also failed to attenuate the hyperalgesic effect of kainic acid administered i.p. , indicating that the spinal cord is not the primary site of action. Kainic acid injected subcutaneously in the back of mice decreased response latencies in the hot plate and tail flick assays, indicating that hyperalgesia is achieved by a variety of parenteral routes of injection. Histological evaluation of rat spinal cord and dorsal root ganglia revealed no neurodegenerative changes 24 h after kainic acid. Together these data suggest that a persistent hyperalgesia results from the transient activation of AMPA/KA receptors that are located outside the spinal cord, perhaps on the distal projections of primary afferent fibers.

Death of a wild wolf from canine parvoviral enteritis.

A 9-mo-old female wolf (Canis lupus) in the Superior National Forest of Minnesota (USA) died from a canine parvovirus (CPV) infection. This is the first direct evidence that this infection effects free-ranging wild wolves.

Possible role of the N-terminus of substance P in kainic acid-induced toxicity in rats.

Subcutaneously administered kainic acid (KA) in the rat results in brain damage accompanied by a behavioral response characterized by wet dog shakes (WDS), seizures and brain damage, an effect that is potentiated by opioids. Based on the potentiative effect of the N-terminus of substance P (SP) on the ability of KA to induce behavioral responses in mice, we tested the hypothesis that the N-terminus of SP also plays a role in KA-induced neurotoxicity in rats. Pretreatment i.p. with 1 or 10 nmol of SP(1-7), a major N-terminal metabolite of the undecapeptide SP, 15 min before administration of 12 mg/kg of KA potentiated the incidence of WDS. In contrast, after administration of 1 nmol of [D-Pro2, D-Phe7]SP(1-7) (D-SP(1-7)), the D-isomer of SP(1-7) and a substance P N-terminal antagonist, the intensity of KA-induced WDS was no different from those in either the KA- or saline-injected rats. However, pretreatment with D-SP(1-7) completely blocked the potentiative effect of SP(1-7) on the KA-induced WDS. While the severity of KA-induced lesions was not significantly altered by pretreatment with 1 nmol of SP(1-7), the effect of KA was not significantly different from that in control rats when administered with 1 nmol of D-SP(1-7). These results suggest a possible involvement of endogenous SP N-terminal activity in the effects following subcutaneous (s.c.) administration of KA.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective potentiation of NMDA-induced activity and release of excitatory amino acids by dynorphin: possible roles in paralysis and neurotoxicity.

Selective antagonists of N-methyl-D-aspartate (NMDA) excitatory amino acid (EAA) receptors have been shown to protect against dynorphin-A (DYN)-induced paralysis and neurotoxicity in the spinal cord. To test the hypothesis that either DYN-induced paralysis or neurotoxicity involves an enhanced release of EAAs, we used microdialysis to monitor aspartate (Asp) and glutamate (Glu) release in both the lumbar spinal cord extracellular fluid (ECF) and the spinal cord cerebral spinal fluid (CSF) of conscious rats in response to DYN (1-13). Injection of 5 nmol of DYN produced temporary paralysis in 8 of 10 animals, but did not significantly change Asp or Glu release in either the ECF or the CSF. Injection of 20 nmol of DYN caused permanent paralysis and neuronal cell loss in all animals tested as well as a significant increase of Asp and Glu in both the ECF and the CSF, and a decrease in glutamine (Gln) release only in the ECF. Pretreatment with 1 mg/kg of the NMDA antagonist MK-801 blocked both paralysis and amino acid changes in the ECF. Pretreatment of animals with 5 mg/kg naloxone inhibited glutamate release in the ECF, but did not block paralysis, Asp release or inhibition of Gln release. As MK-801 sensitive paralysis by DYN was not mediated through enhanced EAA release, we examined whether DYN could act through postsynaptic facilitation of NMDA receptors by testing the ability of DYN to alter the magnitude of a behavioral response produced by intrathecal injection of NMDA in mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Malignant hyperthermia susceptibility: cardiac histomorphometry of dogs and young and market-weight swine.

The defect causing malignant hyperthermia has been proposed to involve cardiac as well as skeletal muscle. We tested the hypothesis that histomorphometric parameters for ventricular wall from malignant hyperthermia-susceptible swine and dogs were abnormal. Hearts were obtained from: mature dogs, age- and weight-matched young swine (89 +/- 15 days, 30 +/- 3 kg); and market-weight swine (102 +/- 10 kg). Using light microscopy, estimates were made for muscle nuclear dimensions and the volume-fraction of nuclei, sarcoplasm, blood vessels, and interstitial space. Cardiac maturation in both MH and normal swine was accompanied by decreased myocyte volume-fraction due to decreased nuclear volume-fraction and increased interstitial space volume-fraction. Sarcoplasm and vasculature volume-fraction were unchanged after maturation. Nuclear volume-fraction was slightly greater (p less than 0.05) in the right ventricle than the left for malignant hyperthermia and normal swine. Myocyte nuclear dimensions were generally similar among animals. Dogs and the oldest group of swine were not significantly different. Myocytes of all swine contained multiple nuclei, closely spaced in rows of 2 to 12. In contrast, most myocytes of mature dogs apparently contained one or two nuclei. Histomorphometric values were not significantly different between normal and malignant hyperthermia young swine and dogs. However, within the market-weight swine, volume-fraction for malignant hyperthermia myocytes and myocyte nuclei was decreased and interstitial space was increased compared to normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of zearalenone on dairy cows.

Doses of 99% pure zearalenone (0.0, 31.25, 62.5, 125.0, 250.0, or 500.0 mg) in gelatin capsules were given once a day per os to 18 nonpregnant, nonlactating, multiparous dairy cows for 2 consecutive estrous cycles. There was no effect (P less than 0.10) on serum progesterone concentrations, RBC, WBC, PCV, hemoglobin, and estrous cycle length. Differential cell counts, clinical health, and sexual behavior were not affected by the zearalenone. One cow from each of the groups given zearalenone and a control were euthanatized at the end of the study. The zearalenone had no effect on the terminal bone marrow smears and did not induce any gross lesions discernible at necropsy or any microscopic lesions in representative samples of 30 tissues/cow. Rectal palpation of the reproductive tracts once a week indicated that the corpora lutea were small in cows given zearalenone. There was a general trend to increased hemoglobin concentrations in cows given the larger doses of zearalenone. Zearalenone of and by itself does not seem to be an important factor in dairy cow health.

Effect of zearalenone on the fertility of virgin dairy heifers.

Eighteen cycling, virgin, Holstein heifers daily were given 250 mg of 99% purified zearalenone in a gelatin capsule orally, and 18 controls were given an empty gelatin capsule once a day. The study lasted through 1 non-breeding estrous cycle and the next 2 consecutive estrous cycles during which the 36 heifers were bred, using artificial insemination. Serum concentrations of progesterone and complete blood cell counts were determined throughout the study. The treated and control heifers had conception rates of 62% and 87%, respectively. There was no effect (P less than 0.05) on the serum concentration of progesterone or the complete blood cell counts. Three heifers, bred but not pregnant by the end of the study, were euthanatized and necropsied. The treated heifer did not have any zearalenone-attributable lesions, and there was no effect seen in the bone marrow smears. The remaining 33 heifers were sold as a herd, and the 31 pregnant heifers calved normally. There was no effect (P less than 0.05) on the sex ratio of the offspring, which were all clinically healthy. Zearalenone did lower the conception rate of the treated heifers (P less than 0.065).

Porcine proliferative enteritis: serological, microbiological and pathological studies from three field epizootics.

Three outbreaks of porcine proliferative enteritis were evaluated clinically, pathologically, microbiologically and serologically. The disease was characterized by a chronic intermittent diarrhea. Pathological lesions included a thickened, turbid ileum with the microscopic appearance of proliferating ileal crypt epithelial cells. Comma shaped intracytoplasmic organisms were observed in the apical portions of the proliferating crypt epithelial cells with a Warthin-Starry silver stain. Microbiologically, both Campylobacter sputorum subspecies mucosalis and Campylobacter hyointestinalis, were cultured from ileal specimens of seven pigs with lesions of porcine proliferative enteritis. Microagglutination antibody titers were determined on sera from 12 of 14 pigs with porcine proliferative enteritis and on sera from 91 clinically normal swine. Pigs with porcine proliferative enteritis had a low antibody titer to subspecies mucosalis that ranged from 1-3 with a mean of 2.17. A varied C. hyointestinalis titer from 3-7 with mean of 4.83 was determined. Titers to either subspecies mucosalis and C. hyointestinalis were higher in non-porcine proliferative enteritis pigs. The results indicate that the presence of a positive titer to either C. hyointestinalis or subspecies mucosalis in swine is not indicative of clinical disease. The isolation of C. hyointestinalis from diseased ileal specimens (porcine proliferative enteritis) confirms previous reports implicating this agent in the disease.

"Campylobacter hyointestinalis" sp. nov.: a new species of Campylobacter found in the intestines of pigs and other animals.

The name "Campylobacter hyointestinalis" sp. nov. is proposed for a Campylobacter species that was isolated from the intestines of pigs with proliferative enteritis. "C. hyointestinalis" is also found in the feces of cattle and has been isolated from the intestine of a hamster. "C. hyointestinalis" is distinguished from previously described catalase-positive Campylobacter species by colony morphology, ability to produce H2S in triple sugar iron agar, ability to grow anaerobically in 0.1% trimethylamine N-oxide hydrochloride, resistance to nalidixic acid, susceptibility to cephalothin and metronidazole, and hydrogenase activity. Sixteen "C. hyointestinalis" strains were highly related (greater than or equal to 76%) by DNA-DNA hybridization (hydroxyapatite method, 50 and 65 degrees C). Other Campylobacter species were less than or equal to 30% related to "C. hyointestinalis." The type strain of "C. hyointestinalis" is designated 80-4577-4 (= ATCC 35217), and its DNA has a guanine-plus-cytosine content of 36 mol%.

In vitro activities of 47 antimicrobial agents against three Campylobacter spp. from pigs.

The in vitro activities of 47 antimicrobial agents against 30 isolates of Campylobacter species from pigs were determined by the agar dilution technique. The isolates were obtained from pigs with proliferative enteritis and included 10 strains each of Campylobacter coli, Campylobacter sputorum subsp. mucosalis, and "Campylobacter hyointestinalis Gebhart et al." (this name is not on the Approved Lists). Carbadox, furazolidone, nitrofurantoin, gentamicin, and dimetridazole were the most active drugs, inhibiting all three Campylobacter species with a MIC for 50% of the isolates of 2 micrograms/ml or less. Trimethoprim-sulfamethoxazole, cefazolin, sulfachloropyridazine, novobiocin, vancomycin, sulfathiazole, cyclohexamide, bacitracin, p-arsanilic acid, and colistin were the least active, with MICs for 50% of the isolates ranging from 16 to greater than or equal to 128 micrograms/ml.

Immunofluorescent demonstration of Campylobacter hyointestinalis and Campylobacter sputorum subsp mucosalis in swine intestines with lesions of proliferative enteritis.

An indirect fluorescent antibody technique was developed to identify Campylobacter spp in lesions of swine proliferative enteritis (SPE). Rabbit antisera to C hyointestinalis and C sputorum subsp mucosalis were produced. Bacterial smears stained by fluorescent antibody test with homologous antisera differentiated C hyointestinalis from subsp mucosalis. Ileal frozen sections from 29 pigs with histologic lesions of SPE had specific fluorescent staining of C hyointestinalis in all 29 and subsp mucosalis in 24. Bacterial structures of C hyointestinalis were seen in large numbers and were broadly distributed in intestinal luminal exudate, mucosal necrotic tissues, surface epithelium, lamina propria, and proliferative cryptal epithelium. Numerous C hyointestinalis organisms were always present in the apical cytoplasm of proliferative cryptal epithelium. Fluorescent subsp mucosalis bacteria were seen less frequently and were distributed focally in the mucosa. Numerous subsp mucosalis organisms were more common in cellular debris and in necrotic tissues of surface mucosa, and less common in the epithelial cells of proliferative crypts. Ileal sections from 13 pigs without SPE had no fluorescent staining of C hyointestinalis and subsp mucosalis.

Campylobacter microagglutination tests of swine with proliferative enteritis.

A microagglutination test was developed to determine campylobacter titers in swine with proliferative enteritis. Formalinized whole cell antigens from 24 Campylobacter isolates, including C hyointestinalis (CHI), C sputorum ss mucosalis (CSM), C jejuni/coli (CJC), C fetus ss fetus (CFF), and C fecalis (CF), were tested with 9 rabbit antisera prepared against each of 3 strains of CHI, CSM, and CJC. The CHI appeared to be antigenically homogeneous. All 6 isolates of CHI agglutinated with homologous antisera at high dilutions and did not react with CSM antisera. Five of 6 isolates of CSM agglutinated with homologous antisera, whereas 1 isolate did not. Seven strains of CJC autoagglutinated in saline solution and various antisera. One of 3 CJC antisera, however, cross-reacted with CHI and CSM antigens at high dilutions. The antigens from 5 strains of CFF and CF did not react with CHI, CSM, and CJC antisera. A survey of sera from 1,052 adult pigs from production herds indicated that the majority had high titers to CHI and CSM (mean, in log2: CHI = 5.57, CSM = 6.05). Similar titers were found in weaned pigs from 3 herds with the disease and 2 of 3 herds without the disease. Pigs with confirmed lesions of proliferative enteritis, however, had low titers (mean in log2: CHI = 2.44, CSM = 3.11). Agglutinating antibodies to CHI and CSM were transmitted from farrowing gilts to neonatal pigs via colostrum. The acquired antibodies decayed to low levels in pigs at 4 weeks of age (mean in log2: CHI = 1.09, CSM = 1.27).

Campylobacter hyointestinalis (new species) isolated from swine with lesions of proliferative ileitis.

Intestines from 48 swine with enteric disease were examined by bacteriologic cultural technique for the presence of various Campylobacter species. Histopathologic techniques were used to determine whether the submitted specimens had lesions of either swine proliferative ileitis or other enteric diseases. Three species of Campylobacter were identified as Campylobacter jejuni/coli, Campylobacter sputorum ss mucosalis, and Campylobacter hyointestinalis (proposed new species) on the basis of biochemical characteristics and response to various inhibitory substances. The C hyointestinalis was isolated from 18 of 27 (67%) swine with proliferative ileitis and from only 1 of 21 (5%) swine with other enteric diseases. The C sputorum ss mucosalis was obtained from 16 of 27 (59%) swine with proliferative ileitis and from 2 of 21 (10%) swine with other enteric disease. The C jejuni/coli was isolated from 2 of 27 (7%) swine with proliferative ileitis and from 8 of 21 (38%) swine with other enteric disease. The new organism, C hyointestinalis, was catalase-positive, hydrogen sulfide positive in triple sugar iron agar, glycine tolerant, intolerant to 3.0% sodium chloride, able to grow at 25 C, sensitive to cephalothin, and resistant to nalidixic acid. On the basis of these characteristics, C hyointestinalis was differentiated from other campylobacters isolated from swine and from other sources.

Effects of continuous intravenous infusion of Escherichia coli endotoxin into swine.

Escherichia coli endotoxin was continuously infused IV into 31 pigs. The response was related to the infusion rate. Of 13 pigs given endotoxin at the rate of 15.4 and 23.1 micrograms/kg of body weight/hour, 10 had bilateral renal cortical necrosis similar to a generalized Shwartzman lesion. All 13 pigs given endotoxin at the rate of 6.6 to 12.1 micrograms/kg/hour survived the infusion and were euthanatized 7 to 12 days later. Most of the pigs that developed chronic neurologic disturbances were given the smaller dose of endotoxin. Of 5 pigs given endotoxin at the rate of 22.0 to 23.1 micrograms/kg/hour after receiving 200 U of sodium heparin/kg of body weight, 1 died during the 48-hour period of infusion and the 4 pigs euthanatized 8 to 12 days later had lesions that were similar to those produced by endotoxin without heparin. The 4 control pigs given continuous IV infusion of isotonic saline solution at a rate of 30 dl/hour had no clinical signs or pathologic lesions. The continuous IV infusion of endotoxin into pigs at various doses produced similar clinical signs of endotoxic shock. Pigs that died acutely had widespread thrombosis. The hematologic findings indicated an intravascular coagulopathy and some of the clinical signs and lesions in the pigs resembled changes in the CNS in pigs with spontaneous edema disease (ED); however, distinct differences were also observed. Fibrinoid vascular necrosis did not occur in the CNS, and this lesion is consistently present in naturally occurring ED. The exact nature of the causal substance or substances causing ED is still unknown, but is considered an angiotoxin associated with hemolytic E coli.

Diacetoxyscirpenol toxicity in pigs.

Purified diacetoxyscirpenol (DAS) mycotoxin fed to growing pigs at 0, 2, 4, 8, and 9 ppm for as long as nine weeks caused several lesions at all levels. The pigs developed multifocal, proliferative, gingival, buccal and lingual lesions. The small intestine had both glandular and mucosal cell hyperplasia. No other lesions were seen at necropsy or in any of the 19 tissues examined microscopically using haematoxylin and eosin stain. A one-way analysis of variance revealed statistically significant (P less than 0.05) decreased ration consumption and weight gain at all levels of DAS. Total ration refusal occurred at 10 ppm of DAS. There was no effect on the packed cell volume, haemoglobin concentration, total red blood cell count, total white blood cell count, 300 cell differential, terminal bone marrow smears or on the serum levels of aspartate transaminase, serum glutamic pyruvic transaminase and lactic dehydrogenase at any level of DAS. Based on the gross and microscopic lesions, decreased ration consumption and decreased weight gain the no-effect level was less than 2 ppm of DAS in the ration.

The failure of purified T-2 mycotoxin to produce hemorrhaging in dairy cattle.

A Holstein cow was intubated with 182 mg of 97% pure T-2 toxin (0.44 mg/kg of body weight) for 15 days. A dairy ration containing 50 mg/kg (50 ppm) of T-2 toxin was refused. A calf, born four days after onset of maternal treatment, was intubated with 26.2 mg of purified T-2 toxin (0.6 mg/kg of body weight) for seven consecutive days and then on alternate days for a total of 16 days. The calf was severely affected clinically by the T-2 toxin. The T-2 toxin failed to cause bovine hemorrhagic syndrome in either animal. Unspecific gastrointestinal lesions were noted in the cow but none were detected in the calf. In the calf, severe depression, hindquarter ataxia, knuckling of the rear feet, listlessness and anorexia were caused by the T-2 toxin.

Effect of zearalenone on female White Leghorn chickens.

Acute toxic effects of purified zearalenone were studied in growing female White Leghorn chickens. In the first experiment, zearalenone in gelatin capsules was administered to 10 chickens (zearalenone-treated chickens [ZC]) in a single oral dose of 15.0 g/kg. Another 10 control chickens (CC) received empty gelatin capsules. All chickens survived the 10-day experiment and did not show any noticeable gross or histopathological lesions. There were no differences between CC and ZC in weight gain, oviduct, comb and liver weights, hematological parameters, and serum cholesterol. ZC had significantly less (P less than 0.05) serum calcium but significantly greater (P less than 0.01) serum phosphorus than CC. In the second experiment, zearalenone was administered orally or intramuscularly (pectoral muscle) at levels of 0, 50, 200, 400, and 800 mg/kg for 7 consecutive days. The oviduct weight increased with increasing toxin levels in both orally (OZC) and intramuscularly (IZC) administered groups: there were more pronounced effects in the IZC. The liver weight increased and comb weight decreased in IZC. The relative estrogenic biopotency of zearalenone in IZC, using estradiol dipropionate as a standard, was 1.37%. The results of this experiment demonstrate that chickens are highly tolerant to zearalenone and that the estrogenic effects of the toxin are greater when it is administered in multiple doses than in a single dose and in IZC than in OZC.

Semen changes in boars after experimental infection with pseudorabies virus.

Two groups of adult boars were inoculated with a field strain of pseudorabies virus (PRV) by intranasal droplet; one group was given 5 x 10(5) median tissue culture infective doses (TCID50), and the other, 5 x 10(6) TCID50. (A third group was maintained as controls.) Ejaculates were examined twice a week for volume, sperm numbers, sperm morphology, and presence of PRV. Severe clinical disease with fever followed administration of the larger virus dose. Death (one boar), testicular degeneration, and transient elevation in spermatozoa with proximal cytoplasmic droplets were seen in different members of this group. The smaller dose resulted in seroconversion, but did not produce signs of disease. In this group, volume, sperm numbers, and sperm morphology did not decline when compared with base-line values or data of control animals. The virus was not isolated from semen. Effects of PRV infection on semen quality in boars seem to be related to the associated clinical signs of systemic disease.