A disease of young Holstein calves characterized by recurrent pneumonia, ulcerative and granulomatous stomatitis, enteritis with bacterial overgrowth, periodontitis, delayed wound healing, persistent neutrophilia and death at an early age had been originally described in 1983 and again in 1987. Most of these calves had stunted growth and a persistent, progressive neutrophilia (often exceeding 100,000/ml). By investigation of pedigrees, all of the affected calves have now been traced to a common sire and confirmed by polymerase chain reaction (PCR) diagnostic DNA testing to be homozygous carriers of a defective allele for bovine CD18. Neutrophils from these calves have several functional deficits and, most importantly, fail to adhere in a ${\beta}_2$-integrin dependent manner. The ${\beta}_2$-integrins represent a family of glycoproteins which participate in various leukocyte adhesion reactions during host defense. The presence or absence of ${\beta}_2$-integrin molecules can be demonstrated on the surface of neutrophils, monocytes and lymphocytes from normal or affected calves using specific monoclonal antibodies and flow cytometry, or by colloidal gold immunolabeling and scanning electron microscopy in backscatter mode. Deficiency of the ${\beta}_2$-integrins on all leukocyte types in Holstein calves is analogous to leukocyte adhesion deficiency (LAD) seen in humans. Neutrophils in bovine (BLAD) and human LAD patients are unable to adhere to the endothelial lining of the cardiovascular system thus interrupting egression of neutrophils into infected tissues. Other leukocytes, while still deficient in expression of the ${\beta}_2$-integrins, are still able to efficiently egress from the blood stream due to interactions of other adhesion molecules that are not as highly expressed on neutrophils. Both BLAD cattle and LAD children (who do not receive bone marrow transplants) often die at an early age as a result of the failure of neutrophils to extravasate into infected tissues. In 1991, Shuster, et $al^{27}$, identified two point mutations within the alleles encoding bovine CD18 in a Holstein calf afflicted with leukocyte adhesion deficiency. One mutation causes an aspartic acid to glycine substitution at amino acid 128 (D128G) in an extracellular region of this adhesion glycoprotein that is highly conserved (> 95% identity) between humans, cattle and mice. The other mutation is silent. Numerous calves with clinical symptoms of leukocyte adhesion deficiency have since been tested and all have been found homozygous for the D128G allele. In addition, calves homozygous far the D128G allele have been identified during widespread DNA testing in the United States. All cattle with the mutant allele are related to one bull, who through artificial insemination (A.I.), sired many calves in the 1950's and 1960's. The carrier frequency of the D128G CD18 allele among U.S. Holstein cattle had reached approximately 15% among active A.I. bulls and 8% among cows. By 1993, the organization of the dairy industry and the diagnostic test developed to genotype cattle, enabled virtually complete eradication of bovine leukocyte adhesion deficiency among current and future A.I. bulls.

Ivermectin is a widely used broad spectrum antiparasitic agent in veterinary medicine. In this work, we examined the pharmacokinetic parameters and the tissue residue profile of a new injectable formulation of ivermectin developed for pigs. The plasma ivermectin levels reached the peak at about 9 and 2 hours after the administrations in young and adult pigs, respectively. But the elimination half-life (3-3.5 days) and the $C_{max}$ values (24~28 ng/ml) were not significantly different between young and adult pig groups. When compared to the reference formulation, the $C_{max}$ of test formulation was higher and $T_{1/2}$ values were shorter than those of the reference formulation, respectively. The tissue residue levels were dose- and time-dependent and were higher in the liver and fat, than in the other tissues such as the injection sites, the kidney, intestine, muscle, plasma (4~74 ng/g) at the 7th day after the administration of both formulations of ivermectin. Then, the mean tissue ivermectin levels at the 21st day after the administration in all the tissues decreased to 7.4 and 25% of the 7th day levels in the test and reference formulations, respectively. In general, the tissue levels of ivermectin in the animals treated with the test formulation decreased more rapidly than those with the reference formulation. The tissue to plasma distribution ratio (T/P ratio) of ivermectin was higher in the liver and fat than other tissues. The T/P ratio in the liver of animals treated with the test formulation was somewhat higher than that in the animals treated with the reference formulation. Taken together, the results of pharmacokinetic and tissue residue studies indicate that the test formulation of ivermectin for subcutaneous injection is comparable to the reference formulation, but unique in that it has higher peak plasma concentrations, shorter elimination half-life and higher T/P ratio in the liver than the reference formulation.

Bovine somatotropin is known to improve the growth rate and lactation in cattle. In this study, we examined the concentration-time profiles of a sustained-release formulation of bovine somatotropin (BST) and insulin-like growth factor-1 (IGF-1) in plasma and milk in cows. In addition, the possible effect of co-administrated vitamin ADE complex on the pharmacokinetic parameters of BST and IGF-1 was evaluated. 1. Plasma BST and IGF-1 levels reached the peak at 12~24 and 48 hours after the administration of BST, and plasma half-lives ranged 100 to 137 and 201 to 310 hours, respectively. To 8th day after administration, BST and IGF-1 levels in milk were not significantly different from the control levels. 2. Plasma BST levels showed cyclic pattern with high concentrations in early stage after each injection and following gradual declining during repeated administrations at 2 week intervals, while plasma IGF-1 levels in treated animals did not show such a cyclic pattern, but remained higher than the control levels. 3. Milk BST and IGF-1 levels during repeated treatments were not significantly different from the control levels. 4. Co-administration of vitamin ADE complex yielded slightly increased AUC of plasma BST for high dose group, but such effect was not evident in the IGF-1 levels. Co-administration of ADE complex tended to increase plasma BST levels and decrease the elimination half-life of IGF-1. 5. These results suggest that the BST formulation tested is one of the ideal sustained-release formulation for long term use in dairy industry. As for the co-administration of vitamin ADE complex, the benefit of co-administration with BST is needed to be further evaluated.

In the present study, to understand how gonadotropin-releasing hormone (GnRH) affects ovarian functions in superovulated rats, we examined the effects of GnRH agonist on the ovulatory response, the morphological normality and nuclear maturation of ovulated oocytes, the ovarian weight, the ovarian histology, and the circulating steroid hormone ($17{\beta}$-estradiol, progesterone and testosterone) levels in immature rats pretreated with 30IU pregnant mare serum gonadotropin (PMSG) and supplemented with 10IU human chorionic gonadotropin(hCG). GnRH agonist was intravenously injected via jugular vein catheter every 20min for 4hrs in early follicular phase (from 6hr after PMSG) of superovulated rats. In addition, GnRH antagonist, Antide, was intravenously injected in combination with GnRH agonist to verify the effects of GnRH agonist on ovarian functions. All animals were sacrificed at 72hr after PMSG administration. The administration with GnRH agonist in early follicular phase of superovulated rats caused inhibition of ovulatory response, increased the proportion of abnormal appearing oocytes(especially, in the rats of the group treated with 500ng GnRH agonist), decreased ovarian weight and promote follicular atresia, compared to those from the rats of control regimen that were not treated with GnRH agonist. In addition, the treatment with GnRH agonist in the superovulated rat distinctly decreased serum steroid hormone ($17{\beta}$-estradiol, progesterone and testosterone) levels in preovulatory phase. On the other hand, the inhibitory effects of GnRH agonist treatment in superovulation-pretreated rats on ovarian functions were totally reversed by the combination with GnRH antagonist, Antide. The nuclear maturation of oocytes recovered from the oviducts in immature rats treated with GnRH agonist and/or GnRH antagonist was characterized by prematurity and asynchronization in early follicular phase, which was similar to control group. The overall results of this study indicate that GnRH agonist disturbs directly ovarian function in early follicular phase of superovulated immature rats in terms of ovulatory response and morphological normality of ovulated oocytes. This concept has been further evidenced by the findings of a great decrease in ovarian weight, a marked increase in follicular and a distinct decrease circulating steroid hormone ($17{\beta}$-estradiol, progesterone and testosterone) levels in GnRH agonist treatment regimen in early follicular phase.

Isoeugenol, one of the phenylpropanoid derivatives has been known to inhibit the lipid peroxidation via scavenging effect on hydroxyl or superoxide radical production. We examined whether isoeugenol has a inhibitory effect against N-methyl-D-aspartate(NMDA)-, oxygen/glucose deprivation- and xanthine/xanthine oxidase(X/XO)-induced neurotoxicity or NMDA-induced $^{45}Ca^{+2}$ uptake elevation in primary mouse vertical cultures. We also evaluated whether isoeugenol exhibits inhibitory action on NMDA-induced convulsion in mice. Isoeugenol ($30{\sim}300{\mu}M$) attenuated NMDA- and X/XO-induced neurotoxicity by 11~85% and 83~92%, respectively. In the oxyge/glucose deprivation(60 min)-induced neurotoxicity, isoeugenol significantly(p<0.05) reduced by 32% at the maximal concentration. However, it failed to ameliorate NMDA-induced $^{45}Ca^{+2}$ uptake elevation. Isoeugenol(0.5g/kg, i.p.) delayed 6.5 times on the onset time of convulsion evoked by NMDA($0.1{\mu}g$) compared to that of control. These results suggest that the neuroprotective action of isoeugenol may be ascribed to the modulation of massive generation of reactive oxygen species(ROS) occurred during the ischemic or excitotoxic damage, not by directly affecting the NMDA receptor.

In this study PRRSV was isolated from serum of an infected pig and designated as CNV-1, ORF4 gene was sequenced, and the nucleotide sequence, deduced amino acid sequence and the amino acid sequence of the neutralizing domain was compared with other PRRSV Strains. ORF4 gene of the Korean isolate PRRSV CNV-1 was shown to be 537bp in length, which is the same as US strain ISU55 but 21bp longer than another US strain MN1b, and 15bp shorter than European strain LV. The homologies of the nucleotide sequences between the Korean isolate CNV-1 and the US strains ISU55, MN1b and European strain LV were 91.8%, 88.1%, 67.6%, respectively, and the homologies of the deduced amino acid sequences were 94.4%, 84.4%, 68.5%, respectively. The neutralizing domain of the CNV-1 was shown to be 36 amino acids in length which is the same as ISU55, MN1b, but 4 amino acids shorter than that of the neutralizing domain reported in LV. The homologies of the amino acid sequences of the neutralizing domain between the Korean isolate CNV-1 and the US strains ISU55, MN1b and European strain LV were 92.5%, 85%, 57.5%, respectively. The molecular characteristics of ORF4 gene of the Korean isolate PRRSV CNV-1 shown in this study suggests that the CNV-1 is genetically closer to the US strains. Also the wide variation of the neutralizing domain between the CNV-1 and LV suggests that there is substantial immunogenic variation between the two strains.

Anthrax caused by Bacillus anthracis is one of the most important zoonotic diseases. The bacterium produces several virulence factors. Of the factors, protective antigen (PA) of tripatite toxin has been identified as a central component in the pathogenesis of anthrax. However, precise roles of PA and other cellular components in the reaction with the target cells remain to be elucidated, especially in the initial stage of the disease. Three B anthracis antigens were prepared for investigation; PA, sonicated cellular antigens (S-Ag) and formalin-inactivaed whole cell antigens (W-Ag). PA was purified from culture supernatant of the bacterium using FPLC system with MonoQ. S-Ag and W-Ag were prepared by sonication and formalin inactivation of the cultured cells, respectively. Purity of the antigens was confirmed by SDS-PAGE and Western blot analysis. The roles of these antigens in the production of inflammatory mediators such as NO, IL-6 and $TNF{\alpha}$ from mouse peritoneal macrophages were investigated. PA alone did not induce the production of the inflammatory mediators while the other antigens, S-Ag and W-Ag, did in a dose and time dependent manner. These results suggested that in addition to major virulence factors, other cellular antigens are also involved in the initial stage of the disease by the induction of inflammatory mediators.

Pathogenic effects of 29 different porcine reproductive and respiratory syndrome(PRRS) virus isolates were investigated in swine tracheal ring(STR) cultures by examining their effects on the ciliary activity of STR. Inhibition of ciliary movement and destruction of the tracheal epithelium were seen between 72 and 96 hours postinoculation(PI). Virus replication was demonstrated by examining viral infectivity of the supernatants from the STR cultures. PRRS virus antigen in macrophages was detected by a streptavidin-biotin complex(ABC) immunoperoxidase method. Of the 29 PRRS virus isolates, 8 isolates were classified into pathogenic, and the remaining 21 isolates were determined as mildly pathogenic or apathogenic viruses. These results suggest that STR examination may be used as a method for predicting pathogenic variability of PRRS virus isolates.

Respiratory pathogenic effects of several porcine reproductive and respiratory syndrome virus(PRRSV) isolates were examined in swine tracheal ring(STR) cultures by examining their effect on ciliary activity. One high and one low pathogenic PRRSV isolates were then selected and their pathogenicity investigated in 3-week-old conventional PRRSV-seronegative pigs. Ten pigs each were inoculated intranasally with the high or low pathogenic PRRSV isolate and 6 pigs were sham inoculated as negative controls. Two pigs each from the inoculated group and one pig each from negative control group were killed on 4, 7, 14, 21 and 28 days postinoculation(pI). At necropsy, degrees of gross lung lesion was determined. Turbinate, tonsil, trachea and lung samples were collected for virus isolation or histopathology. Gross lung lesions were observed mainly on 14 days PI with high and low pathogenic isolates inducing moderate diffuse and mild gross lung lesions, respectively. Inoculation of either the high or low pathogenic virus resulted in loss of cilia in ciliated epithelium of turbinates and trachea between 7 and 28 days PI. High pathogenic virus caused increased number of Goblet cells in the tracheal epithelial layer between 4 and 21 days PI whereas the low pathogenic virus did it between 14 and 28 days PI and with a lesser degree. Although both viruses produced interstitial pneumonia, the lesion was less severe with the low pathogenic virus. The isolation of high pathogenic virus from tissues and sera was earlier and more consistent than that of the low pathogenic virus. The agreement between in vitro and in vivo tests indicates that STR cultures may be used as a routine method to determine the respiratory pathogenicity of PRRSV isolates.

The transposon TnphoA was used to generate avirulent mutants from a type A Pasteurella multocida. A suicide vector plasmid pRT733 carrying TnphoA, having the kanamycin resistant gene and harbored in Escherichia coli K-12 strain SM10(${\lambda}pir$), was mated with streptomycin resistant P. multocida P-1059 strain as recipient. This resulted in the generation of two TnphoA insertion mutants (transconjugants, tc95-a and tc95-b) which were resistant both to kanamycin ($Km^{R}$) and streptomycin ($Sm^{R}$), secreted alkaline phosphatase, and were avirulent to turkeys. Southern blot hybridization using two probes derived from internal fragments of TnphoA, confirmed the insertion of TnphoA into 12.9kb or 13.7kb DNA fragment from the EcoRV digested genomic fragments of transconjugants. The two transconjugants, tc95-a and tc95-b, were distinguishable from their parent strains by differences in ribotypes, and outer membrane protein profiles. TnphoA insertion in both transconjugants also resulted in constitutive expression of a 33Kd iron regulated outer membrane protein (IROMP). The gene encoding $Sm^{R}$ was also located within the same 12.9kb EcoRV genomic fragment from both transconjugants. Furthermore, our finding that the recipient P. multocida P-1059 $Sm^{R}$ strain and both transconjugants were avirulent to turkeys suggest that the either 12.9kb or 13.7kb genomic DNA contains the virulence gene and speculate that the presence of $Sm^{R}$ gene or TnphoA insertion may be responsible for regulating and inactivating the gene(s) encoding virulence in P. multocida.

Twenty three strains of Escherichia (E) coli O157 : H7 isolated from Korea, Japan, USA were analyzed by pulsed-field gel electrophoresis (PFGE) of XbaI-digested chromosomal DNA and multiplex polymerase chain reaction. Various PFGE patterns of E. coli O157 : H7 were found on the same farm. Most of the E, coli O157 : H7 strains had shiga-like toxin (slt) II gene only (43.5%) or both slt I and slt II genes(30.4%). eaeA gene was highly conserved in the E. coli O157 : H7. There was no correlation between PFGE and slt gene patterns. The results indicate that various genotypes of E. coli O157 : H7 have spread throughout the country and genomic DNA patterns generated by PFGE are highly specific for different strains and have significant value in epidemiologic investigations of infectious disease outbreaks.

Vancomycin resistant enterococci (VRE) have emerged as an important nosocomial pathogen. Since 1989 the Center for Disease Control, United States, has reported a rapid increase in the incidence of enterococcal bacteremia and endocarditis infection by VRE. It was suggested that the use of avoparcin was associated with the appearance of VRE in animal husbandry. To date, several detection methods have been used based on conventional methods of culture and gene detection. However, these methods have some limitations such as time-consuming, laborious and additional differential needs. Therefore, In this study a multiplex PCR method was established to detect and differentiate resistance types of enterococci which specifically amplify the four van genes encoding vancomycin resistance elements. Using the method, we investigated the incidence rates and types of VRE from farms using or not using avoparcin. A total of 1091 animal fecal samples were collected from 70 pig and 32 poultry farms. A total of 425 of enterococci were isolated from samples. Of the 425 isolates, 11 of the them showed a pattern of high-level vancomycin resistance (MIC : $64{\sim}256{\mu}g/ml$) which was associated with the presence of the vanA or vanB gene. Fifty-seven isolates showed a pattern of low-level vancomycin resistance (MIC : $3{\sim}8{\mu}g/ml$) associated with the vanC-1 or vanC-2 gene. Interestingly, all isolates with high-level vancomycin resistance were from farms that have never used avoparcin. Moreover, the high-level VRE isolation rate in Korea (2.58%) was much lower than that of other countries (50% in England, 7% in Belgium) where avoparcin have been used. In conclusion, the multiplex PCR method established in this study could be applied for detection of VRE.

New emerging post weaning multisystemic wasting syndrome (PMWS) threatening swine industry worldwide and investigation of the etiological agent is underway. The porcine circovirus (PCV) consistently identified from PMWS pigs and research result indicate that there is strong relationship between PCV and PMWS. Fauns with PMWS submitted pigs suffered from various PMWS typical signs and necropsy finding showed lymph node anomalies. The PCV DNA was amplified from inguinal lymph node collected from pigs with PMWS. PCV specific primers were successfully amplified PCV DNAs and were able to differentiate PCV type I and II. We have identified noble PCV virus with genetic variation. The virus showed insertion of the nucleic acid at the 5' of the genome but did not have PCR product with primer set corresponding to PCV type II virus.

We investigated the pathological changes in young rabbits which were experimentally infected with rabbit hemorrhagic disease virus (RHDV). Experimental infection of RHDV was carried out in both thymectomized and non-thymectomized young immature rabbits and adult rabbits. None of young rabbits infected with RHDV died during the experiment. Histologically, single or focal hepatocellular degeneration and necrosis with mild lymphocyte infiltration were observed in the rabbits killed at 30 hours and 5 days PI. Lymphocyte infiltration was more severe at 5 days PI than at 30 hours PI. RHDV antigens were mainly detected in the degenerating hepatocytes adjacent to the infiltrated lymphocytes at 30 hours PI and 5 days PI. In electron microscopical observation, infiltrated lymphocytes in the lesions had large nuclei without cytoplasmic granules and interdigitated with adjacent hepatocytes. It is assumed that infiltrated lymphocytes in hepatic lesions in RHDV infected young rabbits are T-lymphocytes and originate from peripheral lymphoid organs or tissues rather than from thymus.

A study on quinolone antibacterial, norfloxacin, was performed to apply for the control of bacterial diseases in eel (Anguilla japonica). Norfloxacin was proved excellent in antibacterial activity and sensitivity against fish bacterial pathogens when compared with the existing antibacterials and antibiotics. And any side effect was not observed during the period of indicated use. An outline of minimal inhibitory concentration was $0.03{\sim}0.1{\mu}g/ml$, $TLm_{48h}$ value was 3,500mg/l. The residual time of the day in fish body was less than 17 days and any pathological changes were not observed. The study has revealed that norfloxacin can be applied to treat some fish bacterial disease by the dosage of 100g/day/ton of fish body weight for about 3 days perorally. Further, norfloxacin may be used for the control of bacterial pathogens in eel.

Owner's attitudes for tendonectomy, the advantages of this surgical technique, and postoperative complication were investigated by telephone survey. 18 cats on whom tendoncetomy was performed with or without concurrent ovario-hysterectomy or castration were included in this study. The first reason for tendonectomy was to avoid damage caused by the cat's scratching household materials. The first benefit of tendonectomy was decreasing damage to materials (89%). The primary concern of the owners of cats that underwent tendonectomy was postoperative pain after surgery (61%). Twelve cats (67%) that underwent tendonectomy recovered fully within the first three days and 6 cats (33%) recovered within two weeks. After combining the very positive rating and positive as positive, seventeen owners (94%) of cats that underwent tendonectomy had a positive attitude to the surgery.

A methicillin-resistant Staphylococcus aureus (MRSA) isolate was recovered from a 9-month-old female Shih-Tzu dog with canine distemper virus infection. We performed in vitro antimicrobial susceptibility test to determine the most effective antimicrobial drug against the isolate and thus, to emphasize its potential clinical importance in animal practices. Isolate was confirmed MRSA by oxacillin agar screening test. The isolate was fully resistant to all $\beta$-lactam antibiotics and was susceptible to glycopeptides. Of the other antibiotics, mupirocin, TMP/SMZ (trimethoprim-sulfamethoxazole), and chloramphenicol showed inhibitory effect at the concentration of 4x MIC. The MICs ranged 0.25->$128{\mu}g/ml$, and MBCs ranged 0.5->$128{\mu}g/ml$. The combined TMP/SMZ with cefamandole or novobiocin showed synergistic effect, whereas the combination of novobiocin plus cefamandole or teicoplanin resulted in antagonistic effects. Although MRSA in animals so far has been reported in the geographically limited countries, at least theoretically, it could be occurred in the future more frequently through either human or animal origin. The use of this combination may be of value in this situation. As with all antimicrobial agents, inappropriate or unnecessarily prolonged therapy may contribute to the emergence of resistance strains and loss of efficacy.

A randomized experimental study was done to evaluate short course therapeutic efficacies of two types of mupirocin ointment (Bactroban Nasal and Bactroban) in the elimination of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization (16 dogs) and wound infection (3 dogs or 18 wound sites) in dogs. In each model, dogs being assigned to TR-1 treatment group was given ointment twice a day for two consecutive days, and those that assigned to TR-2 treatment group was given the same dose for three days. Neither TR-1 nor TR-2 regimen was effective to clear nasal carriage completely with a clearing rate of 62.5% and 87.5%, respectively. Whereas, for 2 days at least twice daily application of mupirocin for wound infection was quite enough to eliminate MRSA, with a clearing rate of 83.3~100% by 4 weeks follow-up. No apparent side effects were observed in each model, and in no case was it necessary to discontinue the treatment. Further controlled studies on the elimination of nasal colonization are required to establish cost-effective and efficient regimen on companion animals.

Transcolonic scintigraphy using $^{99m}Technetium$ pertechnetate ($^{99m}TcO_{4}$) was performed in 5 dogs with portosystemic shunts. In all dogs, the activity in the heart was seen before liver activity. Also time activity curve was revered. The mean shunt index in 5 dogs was 82.3% (range 79.6~87.1%). Transcolonic scintigraphy is quick, simple and useful diagnostic method for canine portosysternic shunts.

Thyroid imaging was performed in 53 hyperthyroid cats with technetium-99m as pertechnetate($^{99m}TcO_{4}$). Increased radionuclide accumulation was found in all cats. Thirty-four cats had bilateral enlargements of the thyroid glands and 14 cats had unilateral enlargements. Five cats had multi-focal accumulation of $^{99m}TcO_{4}$ in the ventral neck or mediastinum. Conclusively, nuclear thyroid image is useful method in diagnosis of feline hyperthyroidism.