Defining the concept of 'tick repellency' in veterinary medicine.

Although widely used, the term repellency needs to be employed with care when applied to ticks and other periodic or permanent ectoparasites. Repellency has classically been used to describe the effects of a substance that causes a flying arthropod to make oriented movements away from its source. However, for crawling arthropods such as ticks, the term commonly subsumes a range of effects that include arthropod irritation and consequent avoiding or leaving the host, failing to attach, to bite, or to feed. The objective of the present article is to highlight the need for clarity, to propose consensus descriptions and methods for the evaluation of various effects on ticks caused by chemical substances.

Clinical experience of using multidetector-row CT for the diagnosis of disorders in cattle.

To determine the clinical usefulness of multidetector-row CT for the diagnosis of disorders in cattle, images were obtained from 27 cattle, which were then subjected to postmortem and histopathological examinations. The cattle were divided into three categories of disorder: neurological (18 cases), skeletal (four cases) and other (five cases). In five cattle, which were suspected to have brain diseases, no abnormalities were identified by either CT or histopathological examination. Eight types of lesions were detected by CT in the cattle with neurological and vestibular disorders. The diseases diagnosed included hydrocephalus (three cases), intracranial arachnoid cysts (three cases), otitis media (five cases), cerebral abscess (one case), meningoencephalocele (one case), porencephaly (one case), bicephalus (one case) and rupture of the spinal cord (one case). Lesions were identified in all the cattle with skeletal disorders, including luxation (two cases), fracture (two cases), spondylosis (one case) and congenital disorders of the skeletal system (one case). Morphological disorders in the eyes (one case), nasal cavity (two cases), frontal sinuses (one case), thyroid glands (two cases), lung fields (two cases) and abdominal organs (two cases) were diagnosed by CT.

Detection of Anaplasma phagocytophilum and Ehrlichia sp. HF strains in Ixodes ricinus ticks in Brittany, France.

DNA extracts from 156 tick pools, 18 blood specimens and 17 spleens from European woodmice (Apodemus sylvaticus) collected in Brittany, France were tested by PCR for the 16S rRNA gene of Anaplasmataceae. Positive amplicons were sequenced and confirmed, either by amplification and sequencing of a second gene, or by a second PCR specific for the P44 and gltA genes of Anaplasma phagocytophilum and the gltA gene of Ehrlichia sp. HF. In addition to A. phagocytophilum, the study detected Ehrlichia sp. HF for the first time in Ixodes ricinus ticks. This organism has only been detected previously in Ixodes ovatus ticks from Japan.

Expression of cyclooxygenase-2, P-glycoprotein and multi-drug resistance-associated protein in canine transitional cell carcinoma.

Cyclooxygenase-2 (COX-2), P-glycoprotein (P-gp) and multi-drug resistance-associated protein (MRP) are considered important tumor-associated proteins in humans and dogs. In the present study, we immunohistochemically evaluated the expression of these proteins in canine patients with transitional cell carcinoma (TCC). Of 52 cases, 30 (57.7%) were positive for COX-2, 40 (76.9%) for P-gp, and only 10 (19.2%) for MRP. In addition, 27 samples (27/52, 51.9%) were positive for two markers, while 3 (5.7%) and 5 (9.6%) cases were positive and negative, respectively, for all three markers. No significant correlations were seen for COX-2 and P-gp on Fisher's exact test and Mann-Whitney's test, but a significance was seen on Spearman's rank correlation analysis using the IHC scoring system (P=0.043). These results suggest that P-gp expression is induced by overexpression of COX-2 in canine patients with TCC.

Electrophoretic variation of serum alpha1-antitrypsin treated with neuraminidase.

Purified or crude sera of several different phenotypes of alpha1-antitrypsin were treated with neuraminidase. The mobility of the alpha1-antitrypsin zone was delayed on starch gel electrophoresis following incubation. Treated, M-type alpha1-antitrypsin migrated in a manner similar to the untreated S type. Treated S migrated in a similar way to the untreated Z, and treated Z did so more slowly or cathodally. After exhaustive treatment, alpha1-acidglycoprotein bands appeared near the usual M or F positions. Treated samples still possessed the antigenic activity of alpha1-antitrypsin. The concentration and trypsin-inhibitory capacity were not changed by treatment. Several evaluations and considerations are discussed concerning the metabolism of some types of alpha1-antitrypsin.

Molecular cloning and expression analysis of feline melanoma antigen (MAGE) obtained from a lymphoma cell line.

Melanoma antigens (MAGE) are regarded as inducing tumor-specific immune response and thought to be potential therapeutical agents for cancer immunotherapy. We hereby report the cloning of feline MAGE cDNA obtained from a lymphoma cell line derived from cat malignant lymphoma, and its expression pattern in tumor and normal tissues. The cDNA encoding the MAGE is 1668 base pairs (bp) in length, and contains an open reading frame (ORF) of 936 bp encoding a protein of 311 amino acids. The predicted amino acid sequence has 29-46% of homology with other MAGE proteins from human and mouse. mRNA transcripts for the feline MAGE were detected in certain tumors, but not in adult cat normal tissues except in testis, by reverse transcription polymerase chain reaction (RT-PCR) analysis. This indicates that the expression pattern of feline MAGE mRNA is similar to those of other MAGE family genes in tumors and normal tissues.

Dogs develop resistance to Rhipicephalus sanguineus.

The capacity of Beagle dogs to develop resistance against infestation by adult females of Rhipicephalus sanguineus was investigated. The number of successive engorged females recovered from dogs at the second infestation of the tick was significantly less than at the first infestation. However, there were no significant differences in body weight, body length, body width of engorged females, feeding behavior, preoviposition periods or egg weight.

Prostaglandin E2 production by the cattle tick (Boophilus microplus) into feeding sites and its effect on the response of bovine mononuclear cells to mitogen.

Prostaglandin E2 (PGE2) secretion by the cattle tick Boophilus microplus into feeding sites was quantified. It was detected by the in vitro tube feeding experiment and it was determined that a semi-engorged female tick could produce and transmit 1.8 ng PGE2 into the feeding site. Using the in vitro membrane feeding system, newly molted adult ticks were also shown to secrete 0.04-0.15 ng PGE2 into the feeding site; however, female ticks produced more PGE2 than male ticks. The immune suppressive effect of PGE2 in the saliva of B. microplus on the bovine mononuclear cells (MNC) was also examined. PGE2 in the saliva was suspected of being a major component that inhibited the blastogenic response of MNC to a T-cell mitogen phytohemagglutinin. As bovine MNC are sensitive to low level concentration of PGE2, the PGE2 transmitted into feeding sites was suspected to be sufficient to produce physiological effects on the bovine host.

Molecular survey of Ehrlichia infection in ticks from animals in Yamaguchi Prefecture, Japan.

A total of 82 ticks collected from wild animals and dogs in Yamaguchi Prefecture, Japan were examined for Ehrlichia infection by using polymerase chain reaction (PCR) primers that amplify DNA of most members of the genus Ehrlichia. A DNA sample from an Ixodes ovatus nymph from a bear in Yamaguchi Prefecture, Japan, was positive in the screening PCR. Subsequent PCR using two sets of primers yielded a 1431 bp segment of the 16S rRNA gene and the sequence was very similar to those of E. chaffeensis and E. muris, and a strain variant of a recently described Ehrlichia species isolated from I. ovatus in other prefectures of Japan.

Effects of cattle tick (Boophilus microplus) infestation on the bovine immune system.

The immunosuppressive effect of experimental Boophilus microplus infestation on bovine peripheral blood lymphocytes (PBL) and on host antibody production to a protein antigen (ovalbumin) was examined. Boophilus microplus infestation caused a marginal decrease in the percentage of T lymphocytes in PBL, which was observed in both lightly (5000 larvae) and heavily (40,000 larvae) infested cattle, and began at the second infestation and continued until the end of the fourth infestation. The percentage of B lymphocytes in heavily tick-infested cattle was less than that in non-infested control cattle after the fourth infestation. The response of PBL from tick-infested cattle to phytohemagglutinin (PHA) was always less than that of tick-free cattle after the second infestation. No noteworthy differences were detected between the three stages of tick infestation, that is, 1 week before the peak of adult engorgement, the middle of the peak and 1 week after all ticks had dropped. Boophilus microplus saliva (100 microliters ml-1) suppressed 47% of the response of bovine PBL to PHA in vitro. This suppressive effect of saliva may contribute to the lower responsiveness of PBL from tick-infested cattle. Antibody production by tick-infested cattle was examined during the third and fourth heavy tick infestation. Tick-infested cattle showed a diminished response against ovalbumin after the second immunization. The immunosuppressive effects of tick infestation may play an important role in tick survival or in the transmission of tick-borne diseases in the field.

Survey of tick-borne diseases in dogs infested with Rhipicephalus sanguineus at a kennel in Okayama Prefecture, Japan.

Serological tests were performed to investigate extent of tick-borne diseases in dogs infested with Rhipicephalus sanguineus at a kennel in Okayama Prefecture. Three of 22 dogs (13.6%) were positive for Ehrlichia canis. Two of 19 dogs (10.5%) were positive for Rickettsia japonica. Three of 22 dogs (13.6%) were positive for Babesia gibsoni. None of these animals were positive for Coxiella burnetii or Hepatozoon canis. A microfilaria was detected in a drop smear of hemolymph from an engorged female tick, however, species was not determined. It is possible that these ticks can transmit pathogens to domestic dogs which are rare in Japan.

Establishment of Boophilus microplus infected with Babesia bigemina by using in vitro tube feeding technique.

The in vitro tube feeding technique is used to establish a laboratory colony of Boophilus microplus infected with Babesia bigemina. Pre-fed engorged female ticks offered 2 x 10(4) and 2 x 10(5)/ml of B. bigemina infected bovine red blood cells (RBC) showed sporokinetes in the haemolymph smear sample, and positive signals for B. bigemina in polymerase chain reaction (PCR). Larvae laid from the ticks offered 2 x 10(5)/ml of B. bigemina infected RBC showed evidence for B. bigemina infection in microscopic method and PCR. While larvae laid from the ticks offered 2 x 10(4)/ml of B. bigemina infected RBC showed positive for B. bigemina in only PCR. The females offered 2 x 10(3)/ml B. bigemina infected RBC and their larvae did not show positive evidences for B. bigemina infection. It is thought that the in vitro tube feeding technique can be a convenient method to study the relationship between ticks and tick-borne pathogens. It is also suggested that the superior sensitivity of PCR compared to the microscopic method in detection of B. bigemina from the tick sample, especially in larvae.

Incidence of brown dog ticks, Rhipicephalus sanguineus, at a kennel in Okayama Prefecture.

Twenty two adult dogs suffered from tick infestation at a kennel in Okayama Prefecture in the summer of 1994. Four of them had been introduced from U.S.A. Some dogs showed pyoderma, anemia, neutrophilia or eosinophilia. Neither Babesia gibsoni nor Hepatozoon canis was detected on the smear samples of peripheral blood. The ticks detected were morphologically identified as Rhipicephalus sanguineus. This case was a rare incidence of the tick in the other areas of Japan than Okinawa.

Seasonal occurrence of Rhipicephalus sanguineus in Okayama Prefecture, Japan and effect of temperature on development of the tick.

The seasonal occurrence of Rhipicephalus sanguineus on dogs was examined at a kennel in Okayama Prefecture, Japan. The number of ticks suddenly decreased after treatment with an acaricide in late August. Small numbers of adults and nymphs were detected in September and October, then ticks were not seen on the dogs early in November, when the mean temperature was below 15 degrees C. Then 3 dogs were found to be infested by some adult ticks toward the end of March, when the mean temperature was about 11 degrees C. The effects of temperature on the oviposition and the development of the tick were examined under laboratory conditions. The larval and nymphal post parasitic period, the pre-oviposition period and the oviposition period were prolonged when the temperature was decreased from 37 to 23 degrees C. The oviposition period was extremely long at 14 degrees C, but the tick could not develop below 14 degrees C. No eggs hatched below 14 degrees C. The ability to attach an engorge of adult ticks was examined under cold conditions. Unengorged adult ticks could attach to rabbits on the ear which were kept in an outdoor kennel in October, November and March, however they could not engorge completely in November. They could not attach on rabbits from December to February. The longevity of the tick was also examined under low temperatures. Unengorged adults could attach and engorge on rabbits after kept at 12 degrees C with 50% relative humidity (RH) for 140 days or 12 degrees C with 50% RH for 40 days followed by 4 degrees C with 50% RH for 100 days. These findings suggest that R. sanguineus could be established in Okayama Prefecture under optimum condition.

The relationship between plasma insulin-like growth factor-I (IGF-I) level and body weight in the horse.

The relationship between plasma insulin-like growth factor-I (IGF-I) level and body weight was studied in six breeds of horse. The correlation coefficients between plasma IGF-I and body weight in males and females of 1 year old heavy horses (Percheron and Breton breeds) were 0.62 and 0.12 respectively. The mean plasma IGF-I of males was higher than that of females (p < 0.01). However, the plasma IGF-I levels of heavy horses did not exceed those of light horses (Thoroughbred) or ponies (Shetland and Falabella). These data suggest that IGF-I is at least related to the difference of body weights between sexes in heavy horses.

Development of peripheral blood mononuclear cell response to mitogens in Japanese black newborn calves.

Development of peripheral blood mononuclear cells (PBMC) responses to phytohemagglutinin (PHA) and concanavalin A (Con A) in 5 Japanese Black newborn calves was examined by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay until the day 28 after birth. The PHA responses of PBMC from calves aged from 0 to 7 days were less than those of PBMC from control adult cattle. While the difference of the Con A response of PBMC between newborn calves and adults was not significant statistically. These results suggest that the response of T cell to PHA may be insufficient at early stage after birth in Japanese Black.

Serosurvey of Ehrlichia canis and Hepatozoon canis infection in dogs in Yamaguchi Prefecture, Japan.

Antibodies to Ehrlichia canis and Hepatozoon canis in dogs at the Animal Hospital in Yamaguchi University were surveyed and potential risk factors for both pathogens were evaluated. Among 430 dogs examined, 20 (4.7%) and 18 (4.2%) dogs showed positive findings for E. canis and H. canis, respectively. Neither, sex nor age was associated with the seropositivity of either pathogen, but the positive rate in dogs kept outside was slightly higher than that in dogs kept inside for both pathogens. A higher seropositive reaction to E. canis and H. canis was observed in dogs that lived in certain cities and towns. Beagles, golden retrievers and pointers had higher seropositivity than other breeds in E. canis, whereas shibas, akitas, beagles, pointers and mongrels had higher positive rates than other breeds in H. canis.

Effects of infestation by Rhipicephalus sanguineus on lymphocyte blastogenic responses to mitogens in dogs.

Mitogen blastogenic responses of lymphocytes from dogs infested with adult Rhipicephalus sanguineus and the effects of salivary gland extracts (SGE) of the tick on the blastogenic responses of lymphocytes from normal dogs were studied. Infestation by R. sanguineus significantly suppressed concanavalin A, phyto-hemagglutinin and pokeweed mitogen responses of lymphocytes from dogs. The inhibition of lymphocyte responses of dogs in the first infestation was greater than that in the second infestation. SGE from R. sanguineus also suppressed all mitogen blastogenic responses of lymphocytes from healthy dogs in vitro. These suppressive effects of SGE on the blastogenic responses of PBL to mitogens were significantly inhibited by trypsin digestion. It is suggested that some proteins in SGE contribute to the suppressive effects of SGE on the blastogenic responses of peripheral blood lymphocytes from dogs.

Effects of salivary gland extract from Rhipicephalus sanguineus on immunoglobulin class productivity of canine peripheral blood lymphocytes.

Effects of salivary gland extract (SGE) from Rhipicephalus sanguineus on immunoglobulin class productivity of canine peripheral blood lymphocytes (PBL) in vitro were studied. The detectable limit of the ELISA for canine total immunoglobulin, IgM and A was at least 1, 1 and 15 ng/ml, respectively, and it seems to be useful for the evaluation of non-specific immunoglobulin class productivity in vitro. SGE from R. sanguineus suppressed pokeweed mitogen- or lipopolysaccharide-induced total immunoglobulin and IgA productivity of canine PBL although IgM productivity was not suppressed. These results suggested that the suppression was caused partly by the direct effect of SGE on B lymphocytes.

Comparison of prostaglandin E2 (PGE2) in salivary gland of Boophilus microplus, Haemaphysalis longicornis and Ixodes holocyclus, and quantification of PGE2 in saliva, hemolymph, ovary and gut of B. microplus.

The amount of prostaglandin E2 (PGE2) in salivary gland of semi-engorged adult female Boophilus microplus, Haemaphysalis longicornis and Ixodes holocyclus were 374.3 pg, 427.0 pg and 825.0 pg per one tick, respectively. It was thought that the PGE2 production is a common phenomenon among ticks. Then PGE2 concentrations in saliva and hemolymph, salivary gland, ovary and gut of fully-engorged adult female B. microplus were compared. The PGE2 concentration in saliva induced by pilocarpine was 40.3 ng/ml and hemolymph was 19.1 ng/ml. Salivary gland, ovary and gut from a tick contains 35.5 pg., 27.0 pg and 2.5 ng of PGE2, respectively.