Biomedical subjects

I Vlemmas

Publications and source records attributed to I Vlemmas.

At least 19 recordsLinked to original sources

PubMed2006

Pathogenesis of experimental encephalomyocarditis: a histopathological, immunohistochemical and virological study in mice.

Mice (n=20) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 18-59 days post-infection (dpi), except for two mice that died at 6 and 32 dpi, and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical examination. Apart from the two deaths, the experimental infection was inapparent, but virus was invariably recovered from faeces and several organs. The main histopathological lesions were focal interstitial pancreatitis, depletion of thymus and Peyer's patches, and interstitial pneumonia. Additionally, in the two mice that died, multifocal interstitial myocarditis was observed. EMCV antigen was detected in the cytoplasm of pancreatic acinar cells and in macrophages of the lung and the thymus. Antigen was also detected in the cytoplasm of cardiac muscle cells from three animals, including the two that died. The results support the role of mice, in addition to rats, as reservoir hosts in the epidemiology of EMCV infections on pig farms.

Animals↗

PubMed2006

Detection of maedi-visna virus in the kidneys of naturally infected sheep.

Infections with maedi-visna virus (MVV) cause progressive inflammation in different organs, mainly the lung, mammary gland, brain and joints. The aim of the present study was to investigate whether the kidney represents a viral target in natural MVV infection. For this, kidney samples from 13 sheep naturally infected with MVV were examined by histology, polymerase chain reaction (PCR), and immunohistochemistry. The kidneys of nine animals showed membranoproliferative glomerulonephritis and interstitial nephritis. The inflammatory infiltrate consisted of lymphocytes, plasma cells and macrophages. Interestingly, lymphoid follicles resembling those known to occur in other MVV-infected tissues were observed. Lung tissue from the same animals had typical MVV lesions, such as lymphofollicular hyperplasia and interstitial pneumonia. Maedi-visna proviral DNA sequences were detected in renal and lung tissue samples from these nine sheep by PCR, and the specificity of the amplified products was further verified by DNA sequencing. Moreover, MVV-specific immunohistochemistry revealed viral antigen in affected kidneys and lungs. These results suggest that the kidney may be a common target in natural MVV infection, and raise the issue of the role of this organ in the disease.

Animals↗

PubMed2006

A novel deletion in the LTR region of a Greek small ruminant lentivirus may be associated with low pathogenicity.

Greek small ruminant lentivirus (SRLV) strains remain relatively uncharacterized at the molecular level, despite the fact that lentiviral diseases of small ruminants are known to be widespread in the country. In the present study, we investigated the sequence diversity of the LTR region in Greek SRLV strains from sheep with and without disease symptoms, since sequence differences within this genomic area have been shown to lead to SRLVs with distinct replication rates. The AP-4 and AML (vis) motifs and the TATA-box were highly conserved among Greek strains, whereas the two AP-1 sites exhibited some substitutions. Pairwise comparisons with reference strains revealed that Greek LTR sequences were closer to the ovine strains (25.7% average divergence) rather than the caprine strain CAEV (59.1% average divergence). The most striking difference observed between the two groups of animals was a 13-14 nucleotide deletion in the strains obtained from the asymptomatic sheep. The deletion was located within the R region of LTR, which was also found to be much less homologous (39.6% average divergence) than the U3 and U5. Taken together, our data suggest that the R region of LTR may be involved in virus transcriptional activation. Furthermore, a specific deletion within this region may, at least in part, be associated with low pathogenicity of some SRLV strains.

Animals↗

PubMed2006

Chronic progressive autonomic dysfunction in a dog.

A 3.5-year-old intact male American Pit Bull was presented because of urinary incontinence and dysuria. Constipation, followed by diarrhoea, ocular disturbances and finally regurgitation developed over the next 4 years. Autonomic dysfunction was evidenced by clinical presentation, as well as positive ophthalmic pilocarpine test and subnormal Schirmer tear test. Diagnosis, however, was established through histopathological and immunohistochemical examination. Lesions attributable to inflammatory degenerative neuropathy of the autonomic ganglia, which represents one of the various types of human autonomic failure, were detected.

Animals↗

PubMed2005

Pathogenesis of experimental encephalomyocarditis: a histopathological, immunohistochemical and virological study in rats.

Rats (n=40) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 11-62 days post-infection (dpi) and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical evaluation. This experimental infection was inapparent, but virus was isolated from faeces and several organs of all animals. The main histopathological changes were focal interstitial pancreatitis, degeneration and necrosis of pancreatic acinar cells, depletion of thymus and Peyer's patches, and interstitial pneumonia. EMCV antigen was detected in the cytoplasm of cardiac muscle cells, pancreatic acinar cells and hepatic epithelial cells, and in macrophages of the spleen, lung and thymus. In the heart (the target organ of EMCV in pigs), the presence of EMCV in cardiac muscle cells without lesions lends support to the hypothesis that the rat is a natural reservoir host species of EMCV. The persistence of virus in the macrophages of the thymus may represent a mechanism of perpetuation and reactivation, under immunosuppressive conditions, of the infection.

Animals↗

PubMed2005

First partial characterisation of small ruminant lentiviruses from Greece.

Small ruminant lentivirus (SRLV) infections are widespread in Greece, but SRLVs have never been isolated and characterized. In this study, we present the sequence of a 574-nucleotide (191-amino acid) region of the gag gene of SRLV strains from four sheep and one goat from a single geographic area of Greece. All five sequences appeared to be closely related at both nucleotide (2.1-14.2% variation) and deduced amino acid (1.6-4.2% variation) level. Greek SRLV strains were closer to ovine prototypic strains (average divergence 16.8%) than to the caprine strain CAEV-Co (21% divergence). By amino acid composition, the Greek SRLVs were on the average more than twice as distant from CAEV-Co as from other ovine strains. Phylogenetic analysis suggested that Greek strains segregate into a unique group, separate from, but related to, other ovine prototype sequences.

Amino Acid Sequence↗

PubMed2005

Immunohistochemical investigation of amyloid beta-protein (Abeta) in the brain of aged cats.

To clarify the immunohistochemical features of amyloid deposits and cerebral amyloid angiopathy (CAA), the distribution of the amyloid beta-protein subtypes Abeta40, Abeta42, Abeta43 and Abeta precursor protein (APP) were examined in the brains of fourteen aged cats (7.5-21 year-old). Two types of plaques were detected. The first type was characterized by Ass positive antigenic material and detected in the cortical layers of the frontal and parietal lobes of all examined cats. The second type was characterized by diffuse positive immune staining representing diffuse plaques, which were detected only in the very aged cats (17-21 years old) and distributed throughout the cortical layers of the parietal lobes. Vascular amyloid and the amyloid deposits were strongly positive-stained with the antibody Abeta42. APP was exhibited in neurons and axons while the staining was stronger in the very aged cats (17-21 years old). Our findings suggest that the feline forms a spontaneous model for understanding the early changes of normal brain aging and the early stage of amyloid beta-protein deposition.

Aging↗

PubMed2005

Outbreak of avian mycobacteriosis in a flock of two-year-old domestic pigeons (Columba livia f. domestica).

This report describes an outbreak of avian mycobacteriosis in a flock of 100 two-yr-old pigeons. Over a 6-mo period, the sick pigeons showed cachexia followed by death. In Columbiformes classic tubercles rarely develop, but in these affected pigeons granulomatous nodular lesions of various sizes, containing numerous acid-fast bacilli, were found in the internal organs. The lesions were observed in the liver, spleen, intestine, bone marrow, ovary, and oviduct. Despite their breeding age, atrophy was also found in the ovary and oviduct. Microorganisms belonging to Mycobacterium avium complex were identified in the affected tissues by polymerase chain reaction.

Aging↗

PubMed2004

Vertebral telangiectatic osteosarcoma in a dog.

Telangiectatic osteosarcoma (TOS) affecting the seventh cervical vertebra (C7) was diagnosed in a 4-year-old male dog with signs of locomotor dysfunction. Bone lysis and an extradural-extramedullary mass were observed in radiographs and occipital myelograms. The diagnosis was confirmed by histopathologic and immunohistochemical examination of the mass. The tumor was composed of large blood-filled cavities lined by anaplastic stromal cells (malignant osteoblasts). Around the cavities were characteristic tumor giant cells ("bizarre cells"). Immunohistochemically the tumor cells were positive for proliferating cell nuclear antigen. The lining cells of the cysts were negative for von Willebrand factor. The histologic findings in this case of TOS involving C7 were similar to those seen in other cases of TOS in dogs and in people. Immunohistochemistry was a useful tool for assessing malignancy and for ruling out other differential diagnoses.

Animals↗

PubMed2001

Helicobacter pylori-induced gastritis in experimentally infected conventional piglets.

A conventional nonmutant animal that could be experimentally infected with Helicobacter pylori isolates would be a useful animal model for human H. pylori-associated gastritis. Gnotobiotic and barrier-born pigs are susceptible to H. pylori infection, but attempts to infect conventional pigs with this bacterium have been unsuccessful. In the present study, a litter of eight 20-day-old crossbreed piglets were purchased from a commercial farm. Six of them were orally challenged two to five times at different ages, between 29 and 49 days, with doses of H. pylori inoculum containing approximately 10(9) bacterial cells. Two animals served as controls. The inoculation program began 2 days postweaning when the piglets were 29 days of age. Prior to every inoculation, the piglets were fasted and pretreated with cimetidine, and prior to the first and second inoculation each piglet also was pretreated with dexamethasone. The challenged piglets were euthanasized between 36 and 76 days of age. H. pylori colonized all six inoculated piglets. The pathology of the experimentally induced gastritis was examined macroscopically and by light and electron microscopy. H. pylori induced a severe lymphocytic gastritis in the conventional piglets and reproduced the large majority of the pathologic features of the human disease. Therefore, the conventional piglet represents a promising new model for study of the various pathogenic mechanisms involved in the development of lesions of the human H. pylori-associated gastritis.

Animals↗

PubMed1999

Vitamin B6-deficient diet plus 4-deoxypyridoxine (4-DPD) reduces the inflammatory response induced by T. spiralis in diaphragm, masseter and heart muscle tissue of mice.

Animals fed diets deficient in vitamin B6 develop microcytic anemia, alterations of growth, and other pathologies. 4-deoxypirydoxine is a potent antagonist of vitamin B6 coenzyme which depresses IL-1, TNF and IL-6 and has anti-inflammatory properties. The aim of this study was to show the anti-inflammatory effects of 4-DPD on chronic inflammation caused by the nematode parasite T. spiralis, specifically on the recruitment and the activation of inflammatory cells. Two groups of mice, 6 weeks of age, were used: one was maintained on a vitamin B6-deficient synthetic pellet diet for 15 days before injection of the nematode, and administered an intraperitoneal injection (i.p.) of 4-DPD (250 microg/mouse) for 15 days (the first, 5 days before infection), and the second group was maintained on a normal diet for the total duration of the experiment. These two groups were then injected with 150 larvae (L1-T7 spiralis) per os. Chronic inflammation was caused by infection of treated or untreated mice with T7 spiralis parasite. After 14 days post-infection all mice developed a chronic inflammatory response. Mice fed with a B6-deficient diet showed a significant decrease in the number of cysts found in the diaphragm when compared to mice treated with normal diet. In addition, in all mice treated with vitamin B6-deficient diet plus 4-DPD the average body weight was significantly lower, compared to the mice on normal diet in all weeks examined. Moreover, in sections of the diaphragm, masseter and myocardium muscles, the infiltration of inflammatory cells, such as macrophages, lymphocytes, and eosinophils were more intense in untreated mice compared to those fed a vitamin B6-deficient diet. These results show that BALB/c mice infected with T. spiralis and fed a vitamin B6-deficient diet plus the vitamin B6 antagonist, 4-DPD, prolong the time of invasion of the larvae in the muscle cells, influence the recruitment of inflammatory cells and the intensity of the inflammatory reaction compared to infected untreated mice (control).

Animals↗

PubMed1998

In vivo comparison of the biocompatibility of two root canal sealers implanted into the subcutaneous connective tissue of rats.

The purpose of this study was to evaluate the in vivo biocompatibility of Apexit (a calcium hydroxide) and Pulp Canal Sealer (a classic zinc oxide-eugenol), root canal sealers, after implantation in rat connective tissue. Forty-four white female Wistar-Furth rats were used. Each sealer was placed in Teflon tubes and implanted into specific dorsal subdermal tissues sites. Implants were removed after 5, 15, 60, and 120 days; fixed; and histologically prepared for microscopical evaluation. Severe inflammatory reactions with differing extensions of necrosis were observed with Apexit on the 5th and 15th days. The intensity of the reaction had diminished by the 60th day, and this reduction continued progressively through the 120th day. It was characterized by the presence of connective tissue with a few macrophages. Moderate to severe inflammation with confined areas of necrosis was observed in the Pulp Canal Sealer specimens on the 5th day. The intensity of the reaction diminished by the 15th, 60th, and 120th days, but remained slightly greater than Apexit through longterm observation periods.

Animals↗

PubMed1998

Influence of zinc oxide and eugenol sealer on concentration of zinc, calcium and copper in rat tissues.

A zinc oxide and eugenol root canal sealer (Roth 811) and sterile saline solution were injected into the dorsal thoracic midline of 70 male Wistar-Furth rats. Every day for the next 7 days, 10 animals were sacrificed by either inhalation. The liver, heart, kidneys and brain were removed from the animals and analysed for zinc, calcium and copper concentrations by flame atomic absorption spectrophotometry. The tissue around the injection site was also surgically removed and prepared for histological evaluation under a microscope. The injection of Roth 811 significantly affected the concentrations of zinc, calcium and copper in some of the examined organs, especially on the 4th and 5th day. The inflammatory reaction adjacent to the material was severe during the first 3 days while on the 7th day the presence of connective tissue with collagen formation was observed.

Animals↗

PubMed1998

Histopathological lesions in lead intoxicated dogs.

The ultra-structural lesions of lead poisoning and the deposition of lead in liver, kidney, peritoneum, cerebellum and retina of dogs were studied. Specimens were obtained from 5 3-4 mo-old crossbreed dogs each injected i.p. with a total dose of 120 mg lead acetate, divided in 10 equal doses of 12 mg, administered every other day. Two dogs were controls. Histopathological examination revealed degeneration of the epithelial cells of the urinary tubules, the endothelial cells of the renal capillaries and the hepatocytes. Characteristic lead inclusion bodies were observed intracytoplasmically and intranuclearly in mesothelial and giant cells of the peritoneum. Lead needle-like inclusions were intracytoplasmically in the interstitial connective tissue cells of the kidney, and substantial quantities of lead were in collagen fibers of the interstitial kidney tissue.

Animals↗

PubMed1996

Generation of TNF alpha, IFN gamma, IL-6, IL-4 and IL-10 in mouse serum from trichinellosis: effect of the anti-inflammatory compound 4-deoxypyridoxine (4-DPD).

Infections caused by the nematode Trichinella spiralis is characterized in the host by an inflammatory response with cytokine production. In these studies we have detected TNF alpha, IL-6, IFN gamma, IL-4 and IL-10 in the serum of 10 mice infected with T. spiralis. Moreover, we detected, for the first time, these cytokines in the serum of mice treated with 4-DPD, a potent antagonist of vitamin B6 coenzyme which has anti-inflammatory properties. 4-DPD was used at 100, 400, 800 micrograms/bolus for 20 days, starting one day before the infection. After 15 days of T. spiralis infection, TNF alpha reached a maximum level, while IL-6 was maximal after 7 days, IFN gamma at 20 days and IL-4 at 14 days. IL-10 was not affected by the T. spiralis infection. When the animals were treated with 4-DPD at the reported dosages and infected with T. spiralis the inhibition of TNF alpha and IL-6, were dose-dependent in the first 7 days while IL-4 was reduced only at 400-800 micrograms/bolus. 4-DPD-treated mice did not statistically (P > 0.05) affect the generation of IFN gamma. In healthy animals the production of cytokines were not measurable, just as it was in non-infected animals treated with 4-DPD. The increase of cytokines such as, TNF alpha and IL-6 may be related to the severity of the disease, boosting the host's resistance to the pathogen and inhibiting parasite survival. In addition, the augmentation of IL-4 production enhances T and B cells and macrophage responses and may stimulate T-cell antibody-mediated response to the pathogen. 4-DPD, an inhibitor of IL-1 and inflammatory reactions, proved to be most effective on TNF alpha and IL-6, which are mainly produced by macrophages.

Animals↗

PubMed1996

Experimental study of the biocompatibility of a new glass-ionomer root canal sealer (Ketac-Endo).

Ketac-Endo, a new glass-ionomer cement for endodontic use as root canal sealer, and Tubli-Seal were tested for tissue biocompatibility in rat connective tissue. Forty-four white female Wistar-Furth rats were used. Each sealer was placed in Teflon tubes and implanted subcutaneously. The implants were removed after 5, 15, 60, and 120 days; fixed; and histologically prepared for microscopical evaluation. Mild inflammatory reaction was observed with Ketac-Endo on the 5th day. The connective tissue was infiltrated with plasma cells. Lymphocytes and macrophages were observed. The intensity of the reaction diminished by the 15th day, and this reduction continued progressively through the 60th and 120th days. Severe inflammation with differing extensions of necrosis was observed with Tubli-Seal on the 5th and 15th days, and the material remained irritating even after long-term implantation periods (60 and 120 days).

Animals↗

PubMed1990

[Experimental parvovirus infection of puppies: immunohistological findings].

Formalin-fixed tissue samples obtained from puppies experimentally infected with canine parvovirus type 2 (CPV-2) were investigated immunohistologically with the direct immunoperoxidase method. Besides cardiac muscle and lymphatic tissues, bone marrow, intestine, liver, kidney, pancreas and to a lesser degree lung stained positive for viral antigen and are considered as sites of viral replication. The distribution of viral antigen reveals a tropism of CPV-2 to numerous organs in puppies infected during the first week of life.

Animals↗

PubMed1989

Ultrastructure of Sarcocystis tenella (Sarcocystis ovicanis).

The ultrastructure of the parasitophorous cyst, the metrocytes and merozoites of Sarcocystis tenella (S. ovicanis) was studied. The general ultrastructural features of the cyst wall and the cells of the protozoan, previously described by other authors, were confirmed. The vesicle-like invaginations of the unit membrane (primary wall) of the cyst are identical with the micropinocytic pits of other animal cells, and we believe that they contribute to the nutritional process of the cyst. The Golgi apparatus must be related to the granular endoplasmic reticulum, since the first cisterna of the curved side of the stack appeared to originate from it. The structure of the micropore was similar to that previously described by other workers, the only difference being that in this study, material was frequently observed inside the lumen. This observation led us to support the previously suggested nutritive role. In addition, crystalloid material limited by cytoplasmic membrane was often observed, but the manner of its formation and role remain unknown.

Animals↗