SENSORY ATAXIA IN THE RUNX 3 KNOCKOUT MOUSE

O. Brenner, D. Levanon, C. Cerruti, V. Negreanu, R. Eilam, A. Lev Tov and Y. Groner.
The Weizmann Institute of Science Rehovot , Israel

    Runx 3 belongs to a small family of transcription factors, which play key roles in hematopoiesis and osteogenesis. During development it is expressed in several tissues including the dorsal root and cranial ganglia, where it is localized in trkC neurons. TrkC neurons are large diameter neurons, which relay proprioception. Homozygous disruption of Runx 3 leads to severe congenital ataxia. A marked reduction in the number of large diameter fibers is observed in the dorsal roots and in the dorsal column of the spinal cord, where collaterals of trkC neurons ascend to the cerebellum. Tracing studies employing retrograde DiI labeling and paravalbumin immunostaining demonstrate absence of Ia fibers (Ia neurons constitute the majority of trkC neurons) terminating in the ventral gray matter of the spinal cord. Electrophysiologic examination reveals that short latency mononsynaptic potential is virtually abolished, indicating loss of connectivity between Ia neurons and motor neurons. X-gal staining shows that in knockout embryos, trkC neurons are generated but undergo progressive loss in the dorsal root ganglia. L5 ganglia analyzed at 1 day-old reveal 26% reduction in neurons in knockout mice. TrkC neurons are preserved in double knockout mice produced by crossing Runx 3 knockout to Bax knockout (in which CNS apoptosis is reduced). In contrast to the dorsal root ganglia, neuronal loss is not observed in cranial ganglia. Commensurate with this discrepant effect, muscle spindles are absent from limb muscles but survive in facial muscles. Taken together the data shows that Runx3 is a transcription factor specific to trkC neurons and that its disruption causes congenital-onset ataxia. Emphasis in this presentation will be placed on the various modalities utilized to generate the morphologic data.

NEWLY RECOGNIZED MYCOPLASA DISEASES:  CROSSING THE SPECIES LINE

S. Levisohn
Mycoplasma Unit, Division of Avian and Aquatic Diseases,
Kimron Veterinary Institute, Bet Dagan 50250 Israel

    Mollicutes, commonly known as mycoplasmas, are the smallest self-replicating life forms, with all their functions expressed from a remarkably limited gene repertoire in a genome of as little as 580kb. Mycoplasmas are widely distributed in nature as pathogens of a wide range of hosts. The characteristic high degree of host and tissue specificity has been attributed to the fastidious growth requirements, in vivo as well as in vitro. Only a few mycoplasma species are primary pathogens, but are often implicated in multifactorial or chronic diseases. Especially in the area of human medicine it has been difficult to demonstrate pathogenicity of most mycoplasma species unequivocally. Mycoplasma pathogenesis may result from direct disruption of cell functions (such as ciliostasis), immunomodulation (superantigen, apoptosis or mitogenicity) or antigen mimicry (autoimmune diseases).
    In the new era of molecular diagnosis of infectious diseases, detection and identification does not necessitate isolation of the organism. Our new appreciation of the involvement of mycoplasma species in a wide range of diseases results from the availability of resources to address health issues in the rapidly growing population of immune deficient individuals (AIDS, chemotherapy). Case studies have implicated mycoplasmas usually found in pet cats or dogs, such as M. felis, M. canis or M. maculosum, in disease conditions in pet owners or care-takers. One case of infection of an immune-suppressed slaughterhouse worker with M. arginini resulted in fatal septicemia. Increased awareness will undoubtedly lead to diagnosis of these exotic pathogens in other diseases, both in humans and animals.

THE FIRST MOLECULAR CHARACTERIZATION OF ISRAELI ISOLATES OF AKABANE VIRUS (AKAV)

Y. Stram1, A. Levin2, L. Kuznetzova1, J. Brenner1, Y. Braverman1 and M. Giuni1.
1. Kimron Veterinary Institute, P.O.Box 12 Beit Dagan. 50250.
2. Molecular Virology Department, The Faculty of Medicine, The Hebrew University of Jerusalem, P.O.Box 12272 Jerusalem, 91120.
 

    In the last few decades the ruminant population of Middle Eastern countries including Israel was considered to be endemically exposed to akabane virus (AKAV). More recently, outbreaks of newborn calf conditions with teratogenic malformations in Israel have appeared. Surviving calves were found to have high titers of AKAV and in some cases aino virus (AINV) neutralizing antibodies indicating exposure to those viruses.

    AKAV and AINV belong to the Simbu serogroup of the arthropod-born Bunyaviridae and consists of 24 antigenically different viruses that are related serologically. They can cause severe teratogenic malformations when susceptible pregnant ruminants are infected. Infection of unprotected cows usually causes subclinical viremia of short duration and the virus is cleared rapidly from the blood. In pregnant cows the virus can invade the central nerve system and/or the skeletal tissues of the fetus and may cause arthrogryposis (AG) or hydranencephaly /hydrocephaly/microencephal (HE/ME) encephalomyelitis. Blood-sucking insects such as biting midges and mosquitoes serve as vectors and transmit the viruses to vertebrates. AKAV and AINV were identified serologically or by virus isolation in Japan, Korea, Taiwan, Israel, Turkey, Saudi Arabia and Australia.
The virion is enveloped and the genome consists of three segments of ss (-) RNA. The L segment RNA carrying the polymerase gene, the M segment RNA encodes for the two G1,G2 glycoproteins, and S segment RNA is 858 bases long and encodes for the nucleocapsid (N) and nonstructural (NSs) proteins.

    To enable the detection of traces of AKAV and AINV genomes in affected calves, a multiplex quantitive reverse-transcriptase real-time PCR, using MGB TaqMan chemistry was developed. Each specific probe was labeled with a different fluorescent dye - VICR for detecting AKAV and 6-carboxy-fluorescein (FAM) for detecting AINV.
Calicoidies imicola trapped at the Volcani Center. It was calculated that the insect extract contains 1.5x105 copies of the genome segment S. Following amplification of the entire S genome segment, its nucleotide sequence was determined and found to have over 93.4% identity with the S segment of other AKAV isolates. The deduced amino acid (aa) sequence of the combined nucleocapsid and the non structural protein showed more than 96.6% identity. Phylogentic trees constructed using the combined deduced nucleocapsid and the nonstructural protein aa sequences and the nucleotide showed that the Israeli isolate forms a fourth cluster of AKAV indicating a separate virus lineage.

    AKAV genome was also identified in the brain of a calf with typical Simbu related teratogenic malformations. When trying to amplify the entire viral S segment it was revealed the viral genome is truncated representing only 430 bases from the 5' end of the genome.

 

METHOMYL INTOXICATION IN RAPTORS AND OTHER BIRDS IN THE ZOOLOGICAL CENTER TEL AVIV - RAMAT GAN (SAFARI)

M. Bellaiche1, I. Horowitz2 and V. Handji1
1. Toxicology laboratory, Kimron Veterinary Institute, Bet-Dagan
2. Zoological center Tel Aviv - Ramat Gan (Safari)
 

    In December 2003, a massive bird intoxication occurred in two areas of the Zoological center Tel Aviv - Ramat Gan (Safari). Intensive diagnostic actions as thorough epidemiological investigation, observation of the clinical symptoms, observation of the response of the birds to treatment, blood cholinesterase analysis, biological and GCMS analysis of the suspected materials, lead us to conclude that the birds where intoxicated by the carbamate “Methomyl”. Most of the intoxicated birds were raptors included rare specimens as bearded vultures. In this intoxication, 25 birds were found dead and 34 birds were found with clinical symptoms. Treatment with atropine at 50 mg/kg saved most of the intoxicated birds whilst administration of 2-Pam didn’t help. Only five birds (among them two were treated with 2-Pam) died after treatment. The epidemiological investigation revealed that the source of the poison was a common food-box which was kept outside the cages without supervision.

 

MOLECULAR INTERACTIONS BETWEEN POULTRY VIRUSES, POX AND RETICULOENDOTHELIOSIS VIRUS, WHAT HAPPENS IN ISRAELI BIRDS?

I. Davidson I*, M. Kedem**, I. Skoda* and S. Perk*
* Division of Avian Diseases, Kimron Veterinary Institute, Bet Dagan, Israel
** Akko Regional Avian Laboratory, Veterinary Services, Israel

    An 18 month-old vaccinated layer flock experienced a severe disease of cutaneous and diphtheritic pox. The disease appeared after molting, with a mortality of about 20%, and it appeared clinically as nodular proliferative skin lesions on the chicken non-feathered parts (back, beak, comb, etc.), and with cutaneous and fibrino-necrotic proliferative lesions of the mucous membrane of the upper respiratory tract, mouth and esophagus.

    In recent years infections with FPV appear to be making a comeback in poultry flocks in several countries. In addition, the recent pox cases were associated with reticuloendotheliosis virus (REV) evidences of co-involvement, and even REV sequences integration into the poxvirus. Our presentation initiate a new concern on pox diseases in Israel and is double-motivated; On one hand, the pox morbidity is questionable, facing the existing vaccination, and on the other hand, we inquire the implication of REV in these cases from the molecular aspect. Whether REV infection would be introduced through FPV, acting as a “Troyan”
vehicle for the genome of REV, FPV might have altered activity, on one side, and on the other, might serve as an environmental reservoir for REV. Molecular insertion of retroviruses into large DNA viruses leading to the creation of “chimeric” viruses, was shown in both vaccine and field FPV isolates abroad.

    To reflect the molecular condition of FPV in Israel, and to demonstrate whether REV was also involved, we prepared five experimental systems of molecular amplification; these include the envelope genes of FPV and REV, the REV-LTR and two systems to amplify the junction between the REV and FPV. To demonstrate “true” integration between the two viruses, their sequences has to be shown on the same molecule, in cis. Our results showed a positive amplification in all systems. Further, we sequenced the junctions between the two viruses and found evidences of integration. These findings are shown for the first time in Israel, and raise numerous open questions. 
 

AVIAN INFLUENZA IN ISRAEL – YEAR 2000-2004

E. Shihmanter, I. Gisin, E. Rosenbluth, Pokamunski*, A. Panshin, B. Perlman** and S. Perk
Division of Avian Diseases, Kimron Veterinary Institute, P.O. Box 12, 50250 Bet-Dagan, Israel
* Veterinary Services, Bet Dagan, Israel
**Moshav Mabuim #67, 85360 D.N. Negev, Israel
 

    Since the end of the year 2000, Israeli poultry farms have been suffering from H9N2 Israeli avian influenza virus, which has a very strong economic impact. Today the disease is considered endemic to Israeli poultry farms. The first isolates were obtained from turkey meat type flocks, from which the disease passed on to breeding turkeys, then to broilers and heavy breeders, and finally to laying chickens. It seems that the virus is adapted to infecting several species, including ostrich, which implies that the host range has changed between the year 2000 and the present. Even though all the affected farms are located within a small area, the virus did not affect all the species or types at the same time, supporting the hypothesis of a change in the biological traits of the virus. The Israeli surveillance strategy involves six poultry laboratories that are distributed all over the country, and that are responsible for the initial diagnosis serology and isolation of virus in embryo eggs. When the initial diagnosis is positive the isolates are forwarded for extensive characterization in the Division of Avian Diseases, where the isolates are confirmed by PCR, IVPI, cell culture and sequencing. The clinical aspects vary,depending mainly on the presence of secondary pathogens; these also determine the mortality rates, which range from 0.5 to 100%. The most frequent secondary pathogens are TRT, Pasteurella multocida, Mycoplasma and E. coli. Lesions were found most frequently in the respiratory tract, characterized by fibrous mucopurlent fibrin of varying severity, with occasional occlusion of the airways. It seems that there is a very strong synergy between TRT and Pasteurella, with H9N2 virus which can cause severe diseases. Sequences analysis of the hemagglutinin (HA), nucleoprotein (NP), and neuraminidase (NA) genes of the 35 Israeli isolates of avian influenza viruses (AIV) H9N2 subtype were performed. Sequences analysis of the HA, NP, and NA genes of the Israeli H9N2 AIV strains showed that all these viruses belonged to two related groups and possibly have different progenitors. The Israeli H9N2 isolates were related to influenza viruses isolated in Japan, Hong Kong, and Korea in 1998-2001. Phylogenetic and antigenic analyses of the avian H9N2 viruses isolated in Israel suggest only one lineage

 

INVOLVEMENT OF ROTAVIRUS IN INTESTINAL INFECTIONS OF POULTRY AND PET BIRDS

A. Lublin, S. Mechani and V. Bumbarov
Kimron Veterinary Institute, P.O.Box 12, 50250 Bet Dagan, Israel

    Rotavirus is a double-stranded RNA virus of the Reoviridae family with a three-layer capsid 70-80 nm in diameter lacking an external envelope. The virus is one of the causes of enteritis with diarrhea in birds as in mammals but there is no consensus about cross-infection between the two groups. Rotavirus invades the intestinal mucosal cells especially at the edges of the intestinal villi and injures them. Clinical signs of its infection include retarding of growth and lack of uniformity in the flock, a low food conversion ratio, diarrhea, anemia, abnormal feathering and sometimes lesions in bones. In addition there is immunosuppression and outbreaks of other pathogens such as Clostridium. In broilers we could demonstrate an association with malabsorption syndrome which rotavirus either reovirus seem to be its main etiology. The main pathological lesions of the syndrome consist of white-colored or transparent intestinal walls and enlarged gall bladder, and sometimes also proventriculitis, pancreatic atrophy, degeneration of bursa of Fabricius and rickets. Serological analysis for reovirus in runted flocks were negative in a model of inoculating infected intestinal contents from retarded birds into SPF chicks and serological follow-up of the diseased birds (most of the inoculated). But, in 7-8 poultry flocks out of 18 with signs suspicious of rotavirus, most of them broiler flocks, a rotavirus antigen could be diagnosed by ELISA and by immunohistochemistry against the same antigen, the major inner capsid viral protein VP6. A good correlation have been revealed between these two methods (16 flock tests out of 21 received the same result in both methods, P<0.05). In few cases the virus was diagnosed also by electron microscopy using a negative staining technique, including immuno-electron microscopy. Diagnosis of rotavirus by immunofluorescence was also tested but the results were not satisfactory. The main advantage in using immunohistochemistry is the ability to locate the virus in the tissues (by appearance of a red color). Rotavirus was diagnosed especially in intestinal mucosal cells and in a lesser extent in the inner connective tissue of the mucosa (lamina propria). The virus was observed also inside intestinal contents making the excreted feces in the intestinal lumen as the virus is spreading. The disease could be reproduced in 12 inoculation experiments with filtered intestinal content that have been inserted into crop of SPF chicks, expressed as retarded growth and diarrhea, only when chicks were inoculated up to the age of one or two days. Testing different segments of intestines for rotavirus infection revealed the highest rate of infection in the cecum, in 42% of the cases, and then in the small intestines (in 29% of the cases in jejunum-ileum and 15% in duodenum). Rotavirus was found (using ELISA) also in a relatively high percentage of poultry manures (37% in average) probably due to its high resistance in the environment and accumulation in the manure. Virus prevalence was especially high in turkey manure (about 40%), but it was found in most of the branches, i.e. broilers, breeders, layers, pullets and organic chickens. In pet birds rotavirus is expected as one of the causes of gut dilatation, impaired food absorption etc., and it is widespread especially in pigeons and love birds. Out of 8 cases of birds suspected for presence of rotavirus and tested by ELISA, it was diagnosed only in one case of a ring-necked parakeet from a flock with respiratory disturbances and mortality. Post mortem signs included cahexia, brown-colored diarrhea, proventricular dilatation, undigested food, diminished size of the spleen and pallor of the pancreas and the kidneys.

    To summarize, rotavirus was found by various methods in poultry and in a lesser extent in pet birds, while in poultry it was involved in a syndrome of retarded growth complicated with enteritis and diarrhea. A good correlation was revealed between the different methods of rotavirus diagnosis.

HEMORRHAGIC BOWEL SYNDROME IN DAIRY CATTLE

S. Perl, J. Brenner, D. Elad, D. Lahav and N. Edry
Kimron Veterinary Institute, P.O. Box 12, 50250 Bet Dagan, Israel

 
    Hemorrhagic bowel syndrome (HBS) also known as “bloody gut” and “jejunal hemorrhagic syndrome” is a sporadic acute intestinal disease of milking cows. In the last three years twelve high-yielding dairy cows from various farms in Israel that died suddenly were examined at the Kimron Veterinary Institute.

    The cows were found dead with no history of consistent clinical signs, and in some cases with only a short period of weakness or colic. At necropsy, bloody contents and blood clots were found in the small intestine. In 4 cases a blood clot about 20-30 cm long was found in the intestinal lumen, partially or completely obstructing it. No pathological findings could be detected in other internal organs.

    On histopathological examinations of multiple intestinal sections, severe congestion in the jejunal mucosa with inflammatory cellular infiltration was present. Also numerous bacteria were seen in most cases. Aerobic and anaerobic bacterial cultures and mouse toxicity testing for Clostridial toxins were negative.

    Three main risk factors were common to the dead cows: winter season, adult cows over four years of age and between 90-120 days post partum.

    This appears to be a new syndrome in adult milking cows in Israel, reportedly associated elsewhere with the ß2 toxin of Clostridium perfringens type A.

THE EPIDEMIOLOGY OF CANINE VISCERAL LEISHMANIASIS IN ISRAEL AND THE WEST BANK - AN UPDATE

G. Baneth,1 Z.A. Abdeen,2 D. Strauss-Ayali,1 A. Nasereddin,3 C.L. Jaffe3
1. School of Veterinary Medicine, The Hebrew University, P.O. Box 12, Rehovot 76100, Israel
2. Nutrition and Health Research Center, Al Quds University,Palestinian Authority
3. Department of Parasitology, Hadassah Medical School, Hebrew University
 

    Canine visceral leishmaniasis was reported in central Israel in 1994. A database of the canine cases of visceral leishmaniasis in Israel and the West Bank was constructed and analyzed for the year of diagnosis, geographic location and type of settlement (rural vs. urban). In all, 166 cases of canine leishmanaisis were recorded from 1994 to April of 2004. All cases were diagnosed by positive serology and most were also positive by culture and/or PCR. The average annual number of cases was 16 (range 1 in 1994 - 33 in 2000). These included infected dogs detected by passive surveillance, referrals from local veterinarians suspecting the disease, and by active surveillance in foci of the disease. During 1994-2003, canine leishmaniasis was detected in animals from 47 locations in central and northern Israel and the West Bank. Of these cases, 25% were from northern Israel and 75% from the central region. Ninety percent of the cases originated from rural settlements and 10% from urban settings. Nataf in the Judean hills was the location with the highest number of cases (n=45), followed by Klil (n=21), Nili (n=11) and Modiin-Maccabim-Reut (n=10). The annual number of urban cases and the % of urban cases is gradually rising and reached 4 urban cases (19% of the annual cases) in 2003. The number infected dogs is probably underestimated since not all dogs with clinical signs compatible with leishmaniasis are brought for diagnosis and because dogs can carry infection asymptomatically. The ratio between the number of detected human and canine visceral leishmaniasis cases in Israel is about 1:10. A clear overlap can be found between the regions in which canine and human visceral leishmaniasis are found, however, no clinical human cases have been found in some of the most active rural canine foci of the disease such as Nataf and Klil.

    Financial support: US-Israel Cooperative Development Research Program, Economic Growth. US Agency for International Development (Grant TA-MOU-00-C20-025)

 

RELAPSING FEVER BORRELIOSIS IN A DOG, CAT AND MONKEY IN ISRAEL - MOLECULAR CHARACTERIZATION

G. Baneth,1 T. Halperin,2 M. Yavzuri,2 E. Klement,1,2 Y. Anug,3 H. Almagor,4 I Aizenberg,1 M. Cohensius5 and N. Orr2
1. School of Veterinary Medicine, The Hebrew University, P.O. Box 12, Rehovot 76100, Israel
2. Center for Vaccine Development and Evaluation, Medical Corps, Israel Defense Force
3. PathoVet Diagnostic Veterinary Pathology Services. Kfar Bilu, Israel
4. Haiviva Veterinary Clinic, Jerusalem, Israel
5. Kineret Veterinary Clinic, Moshava Kineret, Israel

    Spirochtemia was detected during the second half of 2003 in a dog, domestic cat and Marmoset monkey that originated from 3 different locations in Israel. The main presenting clinical signs were lethargy and anorexia. All three animals had anemia and thrombocytopenia. A large number of bacteria were detectable as single forms or in clusters of several spirochetes in the blood smears from all animals. The dog and cat improved within two days of antibiotic treatment, however, the monkey died one day after the initiation of therapy.

    PCR amplification of a fragment of the Borrelia glycerolphosphodiester phosphodiesterase (GlpQ) gene was positive in blood samples taken from the dog and cat and in brain tissue taken at necropsy from the monkey (no blood samples were
available from the monkey). Amplification of a 253 bp fragment of Borrelia 16S rRNA gene was positive in blood of the dog and cat. Sequencing of the partial 16S rRNA amplicons showed identity to the sequence for Borrelia persica available at the GenBank. B. persica is the causative agent of human tick-borne relapsing fever (TRBF) in Israel and other Middle East countries. TRBF is a notifiable disease that has been reported from northern, central and some of southern Israel, and is often associated with visiting caves. It causes serious morbidity and is potentially fatal if not treated appropriately. To our best knowledge, this is the first description of B. persica infection in the dog and cat. Future research is warranted to investigate the potential role of animals as reservoirs for this infection

THE IMPORTANCE OF SPLENIC ASPIRATES IN THE DIAGNOSIS AND TREATMENT OF CANINE MONOCYTIC EHRLICHIOSIS

S. Harrus,*1, M. Kenny2, L. Miara1, I. Aizenberg1, T. Waner,3. and S.Shaw2
1. Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Israel;
2. Department of Clinical Veterinary Science, University of Bristol, United Kingdom;
3. Israel Institute for Biological Research, Ness Ziona, Israel

    Doxycycline is commonly used in the treatment of Ehrlichia canis infection, however the length of treatment required is uncertain. The principal aim of this study was to determine the duration of doxycycline treatment required for elimination of E. canis in acute CME using blood and splenic aspirates, during the whole course of the study.

    Five beagle dogs were artificially infected with E. canis-infected blood. After the dogs became severely ill (day 12 post infection (PI)) they were treated with doxycycline (10mg/kg q24h) for 60 days. Blood and splenic aspirates were drawn from the 5 dogs throughout the study. Earliest detection of ehrlichial DNA occurred in both the blood and spleen aspirates on day 7 PI in one dog, and on day 10 PI in the 4 other dogs. No ehrlichial DNA could be detected in any of the blood samples of the five dogs on day 9 PI, however three dogs were PCR positive on splenic aspirates on day 9 for treatment. No DNA was detected in any of the blood and spleen aspirates from Day 16 PI onwards.

    This study presents evidence that dogs recover from acute CME with a proper doxycycline treatment and that they do not remain carriers for life after adequate treatment. The results indicate that the length of doxycycline treatment for acute CME should be reduced to 16 days. The importance of the use of splenic aspirates for the determination of treatment success of acute CME is also indicated.
 

PROGNOSTIC FACTORS FOR ESOPHAGEAL SARCOMAS IN DOGS

E. Ranen, D. Lahav, S. Perl, J. Dank and E. Lavy.

    Esophageal tumors are rare in dogs. Most of the tumors are squamous cell carcinomas and leiomyomas. In areas endemic for Spirocerca lupi, the incidence of esophageal tumors, mostly sarcomas, increase dramatically. Twenty four cases of esophageal neoplasia have been diagnosed at the Hebrew University Veterinary Teaching Hospital in last few years. Sixteen dogs underwent surgical intervention to remove the esophageal tumors, 3 by resection and anastamosis, 1 by partial resection through stomach, 10 by partial esophagectomy and in 2 the tumors were not removed and the dogs were euthanised 1 and 28 days post-operatively. In 8 dogs the owners refused surgical intervention with average survival time of 21 days. Nine dogs survived the immediate post
operative period and all underwent surgery by partial esophagectomy technique; six of them were euthanised 403, 491, 63, 159, 218, 60 days after surgery (average 232 d) and the rest were still alive 610, 387 and 15 days post-operatively. No apparent correlation could be found between survival time and chemotherapy, tumor type and tumor grading except the mitosis count. Surgery seems to be the treatment of choice with relatively quick recovery, disappearance of the major clinical signs and good quality of life post-operatively. Chemotherapy remains unproven. More research on larger number of cases should be done in order to define prognostic factors of esophageal sarcomas.

A GUIDED TISSUE REGENERATION PROCEDURE FOLLOWING TRAUMATIC MALOCCLUSION AND FOREIGN BODY PENETRATION  Veterinary Dentistry
H. Retzkin

    The Periodontium,the apparatus which is responsible for holding the teeth in place is composed of the Gingiva, Alveolar Bone, Cementum and Periodontal Ligament.

    Guided Tissue Regeneration is the process by which we encourage regrowth of the periodontal ligament and alveolar bone cells, while inhibiting the penetration of the epithelial cells to the affected site.
Studies have shown that gingival epithelial cells migrate into the periodontal wound area faster than the periodontal ligament and alveolar bone cells ,thus retarding the healing process.

    The epithelial cells have the ability to repair but not to regenerate, contrary to the periodontal ligament cells property of regeneration which leads to restoration of the original architecture of the Periodontium.

    The Guided Tissue Regeneration procedure is based on the fact that the periodontal ligament cells are the only cells in the immediate area which have the capabiblity to regenerate and differentiate into cementum cells and periodontal ligament cells.
The process is performed by use of a barrier membrane which is placed over the affected site, inhibiting the epithelial cells from penetrating the affected area.

    This case report relates to a 4 year old mixed breed dog which was referred due to a recurrent fistulous tract at the rostral maxillary gingival area between the left upper canine and the left lateral incisive.

    A grade 2 malocclusion (Mandibulla shorter than the Maxilla) was detected upon the physical check up.
This malocclusion had led to a continuous penetration of the lower canines into the upper palate.
The continuous traumatic insult to the upper jaw led to the formation of a periodontal pocket at the level of the palatal (inner) side of the upper left canine, through which a chew toy ,bone chip had penetrated, leading the fistulous tract.
Radiographs of the affected area revealed localized vertical bone loss.
The first step of the treatment plan was to salvage the upper jaw insult which was caused by the lower canines, thus a crown reduction of the two lower canines with a vital pulpotomy procedure was carried out.
Upon completion of the crown reduction procedure, a palatinal and buccal gingival flap between the left upper canine and lateral incisive, was raised, curretage of the area was peformed and synthetic bone was placed at the vertical bone loss site, over which the Collagen Membrane was placed.

    The outcome of the procedure led to regeneration of the periodontium at the affected site, resulting in maintnance of the strong canine tooth in it's natural position!
 

SAPROLEGNIASIS IN FISH - THE DISEASE AND ITS PROMISING TREATMENTS

S. Tinman1 ,R. Falk2 , A. Naor 3, A. P. Benet 3 and I. Polacheck2
1. Central Fish Health Laboratory, Nir David
2. Hadassah-Hebrew University Medical Center, Jerusalem
3. Aquaculture Research Station, Dor

    Saprolegniasis is an infection of freshwater fish and eggs caused by the water mold Saprolegnia parasitica. Saprolegnia release motile zoospores which are considered the infectious unit. In Israel the tropical fish (mainly Tilapia) are kept during the winter season in crowded storage hatchery. The crowded conditions cause stress that weakened the immune system and also affect the epidermal integrity. In addition, the low temperature also suppresses the immune system and also triggers high zoospore production. On fish, Saprolegnia causes tissue destruction and loss of epithelial integrity due to hyphae penetration. If untreated, Saprolegnia leads to death by heamodilution. Malachite green was considered the most effective chemical for controlling Saprolegnia. However, because of concerns about its carcinogenic, mutagenic and teratogenic properties, it is banned in many countries including Israel. In this study we looked for alternatives fungicides to malachite green. We have developed a rapid in vitro screening method for fungicides against Saprolegnia and a model of saprolegniasis in Tilapia. We have found that 3 factors are important for morbidity and mortality: low temperature, concentration of zoospores and a mechanical stress. So far a few compounds looked promising and the mode of action of some of them will be discussed.
 

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References

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