Miguel Ángel Petruccelli

Influence of photoinhibition on the morphology and function of pituitary lactotropes in male golden hamsters.

Inhibition of prolactin (PRL) secretion has been previously shown in pituitaries from male and female hamsters exposed to short photoperiods. The purpose of the present study was to analyze the possible quantitative immunohistochemical and ultrastructural changes of PRL cells in male golden hamsters undergoing regression and spontaneous recrudescence, correlating the morphological findings with circulating PRL levels. Thus, adult male golden hamsters were exposed for 8, 16, 22 and 28 weeks to either short photoperiods (SP: 6 h light, 18 h darkness) or long photoperiods (LP: 14 h light, 10 h darkness). Pituitaries were processed for both light and electron microscopy, and serum levels of PRL were assessed by radioimmunoassay (RIA). Volume density (VD = cell area/reference area) and cell density (CD = number of cells/reference area) of lactotropes were measured with an image analysis system (Imaging Technology, Software Optimas 5.2). One hundred lactotropes were recorded for measuring several ultrastructural parameters. When analyzing the lactrotrope cell population from animals submitted to SP, the VD and CD were found to be significantly (p < 0.05) diminished with respect to those of the groups submitted to LP at weeks 8, 16 and 22. However, at week 28 a spontaneous recrudescence appeared. The lactotropes from animals submitted to LP for 8, 16, 22 and 28 weeks exhibited numerous large electrondense secretory granules. The rough endoplasmic reticulum (RER) presented some flat cisternae and numerous free ribosomes. Animals submitted to SP for 8 weeks showed a number of medium and large secretory granules, and the RER exhibited mainly numerous free ribosomes. In those animals submitted to SP for 16 and 22 weeks, lactotropes were found smaller and showed small and medium-sized secretory granules decreased in number. The Golgi complex exhibited some immature granules and dilated cisternae, while the RER did not present differences with respect to the 8-week SP group. The hamsters submitted to SP for 28 weeks presented medium and large secretory granules, and the RER exhibited dilated irregular cisternae. The ultrastructural morphometric parameters showed a decrease (p < 0.05) in the number of secretory granules and exocytotic profiles, as well as a diminution (p < 0.05) in the areas of Golgi complex, RER, secretory granules, and individual mean area of secretory granule during the 16 and 22 weeks of SP. Serum PRL levels were severely reduced under SP. This decrease was greater at 16 weeks than at 8 weeks of exposure. When hamsters were kept for 22 weeks under SP, PRL levels started their recovery. Thus, at the end of the experiment, the PRL values returned to near those of LP group. In summary, we found quantitative immunohistochemical and ultrastructural, as well as biochemical changes that suggest an inhibition of synthesis, storage and release of PRL in male golden hamsters submitted to SP, with a spontaneous recrudescence appearing at the end of the study.

Thelebolus microsporus Mycelial Mats in the Trachea of Wild Brown Skua (Catharacta antarctica lonnbergi) and South Polar Skua (C. maccormicki) Carcasses

Sixteen brown skuas (Catharacta antarctica lonnbergi) and seven South Polar skuas (C. maccormicki) were found dead near Boekella Lake, Hope Bay, Antarctica, in February 1997. Postmortem examination revealed conspicuous caseous, deep yellow fungal/mycelial mats or cores in the trachea of nine of 19 carcasses that were examined. These mycelial cores, highly suggestive of aspergillomas, completely occluded the tracheal lumen in four of these nine carcasses. Thelebolus microsporus, a psychrophilic ascomycetous fungus commonly isolated from skua dung and skua nesting material, was isolated in pure culture from these tracheal plugs. Awareness of pseudolesions resulting from Thelebolus microsporus profuse postmortem growth in the trachea of dead skuas will minimize potential confusion with aspergillosis when investigating causes of epornithics in Antarctica.

Detection of viral particles in feces of young dogs and their relationship with clinical signs

Gross and light microscopic studies of 100 stool specimens of young dogs were carried out. Viral particles were detected in 31% of the analized samples using negative contrast electron microscopic diagnostic technique. Parvo-like virus, corona-like virus and other non-identified particles were observed in 17%, 7% and 2% of the samples, respectively. Parvo-like and corona-like viruses were found together in 5% of the samples. More than half (58.82%) of the positive parvo-like virus specimens were from dogs aged between 6 weeks and 6 months. 42.85% of the corona-like virus positive samples were detected in dogs between 6 weeks and 6 months and a similar percentage was found in dogs older than six months of age. Dual infections with parvo-like and corona-like viruses were observed in 5% of the samples. Unidentified virus-like particles were found in two specimens. 80.63% of the samples containing viral particles were obtained from dogs with diarrhea.

Dispharynx nasuta (Nematoda:Acuariidae) infection causing proventricular lesions and death in three captive rosellas (Psittaciformes:Psittacidae).

Abstract Two adult male Crimson rosellas (Platycercus elegans) and an adult female eastern rosella (Platycercus eximius) were found dead in their cages in a private aviary in March 2009, April 2010, and February 2010, respectively, without premonitory signs. Their postmortem examination showed pectoral muscle atrophy and a distended proventriculus. The proventricular mucosal surface was covered with a gelatinous, whitish material, where a large number of nematode parasites identified as Dispharynx nasuta were present. A histologic examination revealed a hyperplastic mucosa, spirurid nematodes in the mucosal layer and inflammatory mononuclear cells in the lamina propria. This is the first report of a D. nasuta infection associated with proliferative proventriculitis and subsequent death in psittacine birds.

Detection and molecular characterization of Chlamydia psittaci and Chlamydia abortus in psittacine pet birds in Buenos Aires province, Argentina

In order to determine the presence and genetic diversity of Chlamydia spp. in the north-eastern area of Buenos Aires province, Argentina, conjunctival, oropharyngeal, cloacal swab and tissues were collected from a total of 90 psittacine pet birds of different age and clinical manifestations. Through molecular methods, Chlamydiaceae was detected in 30% (27/90) of the samples, out of which 70.3% (19/27) were positive for Chlamydia psittaci and 14.9% (4/27) for Chlamydia abortus. Nine C. psittaci positive samples were genotyped by ompA gene sequences, 8 clustered within genotype A and 1 within genotype B. A significant association was observed between the presence of Chlamydia spp. and the manifestation of clinical signs compatible with chlamydiosis, as well as with the age of the birds (younger than one year old). This report contributes to the improvement of our understanding of chlamydial agents in our country.

Diagnosis of an outbreak of Salmonella Typhimurium in chinchillas (Chinchilla lanigera) by pulsed-field gel electrophoresis

Adult chinchillas (Chinchilla lanigera) that had suddenly died in a commercial farm located in La Plata City, Buenos Aires Province, Argentina, in July 2012 were macroscopically, histopathologically, and microbiologically examined. Salmonella enterica serovar Typhimurium (S. Typhimurium) was isolated from the liver, spleen, heart, lungs, kidneys and intestines from each of the five animals evaluated. The five strains were susceptible to ampicillin, cephalotin, cefotaxime, nalidixic acid, gentamicin, streptomycin, chloramphenicol, fosfomycin, nitrofurantoin and trimethoprim-sulfamethoxazole, and resistant to tetracycline. Each of the five S. Typhimurium isolates was analyzed by XbaI- pulsed-field gel electrophoresis (PFGE), showing an identical electrophoretic profile with 15 defined bands, which was found to be identical to pattern ARJPXX01.0220 of the PulseNet Argentine National database of Salmonella PFGE patterns. This is the first work describing the postmortem diagnosis of an outbreak of salmonellosis in chinchillas by using molecular methods such as PFGE.

Vaccines against Ornithobacterium rhinotracheale: A Review

Vaccines against Ornithobacterium rhinotracheale: A Review Ornithobacterium rhinotrachealeis a Gram-negative, non-motile, highly pleomorphic, rod-shaped, non-sporulating bacterium of the rRNA superfamily V within the phylum Cytophaga-Flavobacterium-Bacteroides, which has become an emerging pathogen that causes high economic losses in the poultry industry worldwide. Ornithobacterium rhinotrachealeinfection, which is reported mostly in broiler chickens and turkeys, causes respiratory distress, decreased growth, and mortality. The best strategy for their control or prevention is probably vaccination, because most worldwide O. rhinotrachealeisolates have acquired resistance against the antibiotics regularly used in the poultry industry. The purpose of this work is to review the current status of bacterins, live vaccines and subunit recombinant vaccines reported and used for the control of O.rhinotrachealeinfection in commercial poultry under experimental and field conditions.