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Biomedical subjects

O Papadopoulos

Publications and source records attributed to O Papadopoulos.

At least 37 records · Page 2Linked to original sources
PubMed2000

High frequency of loss of heterozygosity on chromosome region 9p21-p22 but lack of p16INK4a/p19ARF mutations in greek patients with basal cell carcinoma of the skin.

Basal cell carcinoma of the skin is the most common neoplasia in humans. Previous studies have shown the existence of allelic imbalance (loss of heterozygosity and microsatellite instability) in BCC on several human chromosomes. Chromosome region 9p21-p22 harbors the CDKN2a/p16INK4a, p19ARF, and p15INK4b tumor suppressor genes. To determine the contribution of these genes to the development of basal cell carcinomas we looked for evidence of allelic imbalance in 67 sporadic basal cell carcinoma specimens from Greek patients and screened 28 of them presenting loss of heterozygosity at 9p21-p22 for germline mutations in p16INK4a and p19ARF genes. Chromosome regions 17q21 and 17p13 were also screened for allelic imbalance in all the 67 basal cell carcinoma specimens. Overall, 69% (46 of 67) of the specimens displayed loss of heterozygosity in at least one microsatellite marker, whereas only six of the 67 (9%) exhibited microsatellite instability. For the 9p21-p22 locus the overall frequency of loss of heterozygosity reached 55% (37 of 67) and is the highest reported. The overall frequency of loss of heterozygosity for the 17q21 locus is 34% (22 of 64) and for the 17p13 locus is 11% (seven of 65). Two of the 28 loss of heterozygosity positive cases were heterozygous for a previously described polymorphism, Ala148Thr, in exon 2 of the CDKN2a gene. This is the first demonstration of polymorphism in the CDKN2a gene in human basal cell carcinomas. No sequence variation in exon 1beta of the p19ARF gene was found. Our results provide evidence of a significantly high occurrence of loss of heterozygosity for the 9p21-p22 locus; however, lack of p16INK4a/p19ARF mutation suggests that these genes seem not to be implicated by mutational inactivation in the development of basal cell carcinoma. Other(s), yet unidentified, tumor suppressor gene(s) located in this locus may be related to this specific type of skin cancer.

Adult↗
PubMed2000

Immunohistochemical detection of encephalomyocarditis virus (EMCV) antigen in the heart of experimentally infected piglets.

Seven 40-day-old piglets were inoculated with encephalomyocarditis virus (EMCV) strain 424/90, isolated from an outbreak of the myocardial form of the disease in Greece. Two non-infected animals were used as controls. Of the seven inoculated piglets, five died suddenly on day 1.5, 2 (two piglets), 2.5 or 4 post-inoculation (p.i. ). The remaining two and the control piglets were killed on day 8 p. i. EMCV antigen was detected immunohistochemically in endothelial cells of capillaries from 1.5 to 2.5 days p.i. only, but was found in cardiac muscle cells, Purkinje fibres and macrophages on all occasions up to day 8 p.i. In endothelial cells and macrophages, EMCV antigen was detected intracytoplasmically, but in cardiac muscle cells and Purkinje fibres it was observed intracytoplasmically or intranuclearly, or both. The frequent presence of EMCV antigen in Purkinje fibres suggests an explanation for the sudden death of the piglets.

Animals↗
PubMed2000

Characterization of the murine BSE infectious agent.

Bovine spongiform encephalopathy (BSE) is a prion-associated disease where the infectious agent is thought to be a host-encoded protein with a protease-resistant conformation (PrP(Sc)). Here, data are presented on the solubilization of purified murine BSE material, using guanidine-HCl as a denaturing agent. This treatment led to loss of infectivity, which was partially recovered on renaturation after dialysis to remove the chaotropic agent. The renatured product was then fractionated on an isopycnic sucrose-density gradient and the fractions were analysed for the presence of PrP(Sc), nucleic acids and infectivity. It was found that the major part of PrP(Sc) (>90%) and the endogenous nucleic acids did not contribute towards the formation of infectious particles on renaturation. Infectivity was distributed in the top three, low-density fractions. Among these, the presence of considerable infectivity in the fraction of lowest density, with barely detectable PrP(Sc), is of particular interest.

Animals↗
PubMed1999

Glycosaminoglycan analysis in brain stems from animals infected with the bovine spongiform encephalopathy agent.

Increasing evidence suggests that the pathological alterations observed in brains affected by neurodegenerative disorders such as Creutzfeldt-Jakob disease and Alzheimer's disease also involve changes in glycosaminoglycans (GAGs). In the present study, we have isolated, purified, and characterized total GAGs from brain stems of healthy cows or those infected with the bovine spongiform encephalopathy (BSE) agent and we report on the differences between the two groups. Purification of the GAGs was achieved by gel filtration after homogenization, delipidation, and sequential treatment with pronase, DNase, and alkali borohydride. Fractionation of the total GAGs by Superose 6 gel filtration and HPLC revealed four major fractions, with average molecular masses of 360, 180, 15, and 2.3 kDa, respectively, both in controls and infected tissues. Enzymatic characterization, using GAG-degrading enzymes, showed that in both infected and normal brain stems, the 360- and 180-kDa fractions correspond to hyaluronic acid, which was also the most abundant GAG, while the 15-kDa fractions correspond to chondroitin sulfates as well as heparan sulfate and dermatan sulfate, the latter being the least prominent GAG. Electrophoresis on cellulose acetate membranes revealed that the relative ratio of GAGs was not significantly modified in infected brain stems, compared to controls. However, total GAGs in infected brain stems was significantly decreased by approximately 40%, compared to controls, and this decrease applied equally to all of the above GAG fractions. The diminution observed in total GAGs in infected brain stems is in good agreement with the recently reported neuroprotective role of certain GAG molecules and offers an additional criterion for differential diagnosis of BSE-infected animals.

Alzheimer Disease↗
PubMed1999

Duration of bluetongue viraemia and serological responses in experimentally infected European breeds of sheep and goats.

The duration of viraemia and the serological responses were studied in two breeds of sheep and two breeds of goats, experimentally infected with bluetongue (BT) virus serotype 4. Viraemia, detectable by cell culture and embryonated chicken egg inoculation, lasted from the third to sixth day until the 27th-54th day post infection (p.i.). Significant differences between sheep and goats were not recorded. Lesbos sheep and goats together appeared to have significantly longer viraemias (n = 9, mean 41.3 days) than east-Friesian sheep and Saanen goats (n = 10, mean 30.4 days, p = 0.0039). Serological response was studied by competitive ELISA (c-ELISA) and agar gel immunodiffusion (AGID) tests. The c-ELISA was more sensitive in detecting BT virus antibodies in all animals than the AGID tests. No significant differences were observed between sheep and goats or between breeds. The epidemiological significance of subclinical infection and the extended BT virus viraemias in Lesbos sheep and goats, in relation to the maintenance of the virus and to overwintering is discussed.

Animals↗
PubMed1999

Sheep poxvirus identification by PCR in cell cultures.

A simple, rapid and specific diagnostic polymerase chain reaction (PCR) method was developed for sheep poxvirus identification. The primers used were from the sequenced genomes of the capripox viruses KS-1 and InS-1. Six different sheep pox isolates were tested against two orf (parapox) and three animal herpesviruses as controls. Material from uninfected cell cultures was also used as control. The sensitivity of the PCR was approximately equivalent with each of the two primers and for the six sheep pox isolates. All the negative control virus DNAs were negative and differed clearly from those of the sheep pox strains.

Animals↗
PubMed1999

Persistence of encephalomyocarditis virus (EMCV) infection in piglets.

Six piglets that had survived experimental infection with encephalomyocarditis virus (EMCV) were treated with dexamethasone for a period of 5 days. The virus had not been detected in excretions of putative carriers for a period of 13-20 days before the treatment. All piglets showed a rise in cardiac isoenzyme (CK-MB) activity, from the first day of treatment, suggesting myocardial damage. Antibody titres against EMCV remained stable or slightly decreased during treatment. EMCV was isolated from blood, nasal and faecal samples from all piglets on days 2 and 3 after initiation of treatment and from various tissues of three piglets. Four contact piglets, that were housed together with the dexamethasone-treated piglets, became infected, indicating that EMCV was shed by treated piglets. It is suggested that recovered pigs may play an important role in the dissemination of EMCV.

Animals↗
PubMed1999

A comparative study of the pathogenic properties and transmissibility of a Greek and a Belgian encephalomyocarditis virus (EMCV) for piglets.

Thirteen susceptible piglets, aged 40 days, were divided into two groups and were experimentally infected either with a Greek (myocardial) or a Belgian (reproductive) encephalomyocarditis virus (EMCV) strain (total dose 5 x 10(6) TCID50, intramuscularly and intranasally). Six piglets were placed in the same rooms, 24 h later, as contact controls. The following criteria were studied: ante mortem: clinical signs, serum cardiac isoenzyme activities (CK-MB and LD-1), viraemia, nasal and faecal virus excretion and serological response. Post mortem (after death or euthanasia): gross lesions, virus isolation from tissues, RT-PCR, as well as histopathological and immunohistochemical findings. The Greek strain was more pathogenic, producing mortality, with high cardiac isoenzyme activities and pronounced macroscopic myocardium lesions. The Belgian strain was able to induce mild heart lesions, as detected only by cardiac isoenzyme activity and histopathologically. All contact pigs were infected, within the first 1-2 days of their introduction, that coincided with the period of viral excretion by the experimentally infected pigs (up to the 3rd day post infection). Disease was mild, with no mortality.

Animals↗
PubMed1999

Second-line chemotherapy with cisplatin-ifosfamide in patients with ovarian cancer previously treated with carboplatin-cyclophosphamide.

In an effort to use antineoplastic drug combinations which are active in platinum resistant ovarian cancer or which can induce a second response after a platinum first-line treatment, we conducted a study on 30 ovarian cancer patients previously treated with carboplatin plus cyclophosphamide who were given ifosfamide 5 g/m2 i.v. divided over days 1 to 3 plus mesma combined with cisplatin 100 mg/m2 i.v. divided over days 1 to 3 every 4 weeks as second-line treatment. Eight patients had never entered remission with first-line chemotherapy while 22 patients had tumor recurrence within 6 to 18 months after the end of chemotherapy and their tumors were considered potentially platinum sensitive. Responding patients received 6 courses while palliative treatment for nonresponders was provided. Of the 22 patients with tumor recurrence, 8 patients responded with one partial response (PR) and 7 complete clinical responses (CCR). Two out of the 8 patients with platinum resistant disease demonstrated short lasting PR. Seven patients with CCR underwent second-look operation and in two a pathological CR was documented. Median time to progression was 6 mo (4-12). The median overall survival was 12 mo (4-20). Myelotoxicity despite G-CSF administration was significant with grade 4 leukopenia in 40% and grade 3 thrombocytopenia in 20% of patients. Central nervous system (CNS) toxicity was significant with 30% somnolence, 20% disorientation and an episode of grand-mal epilepsy ascribed to ifosfamide. With a 33% response rate the combination is as effective as new agents employed in relapsed ovarian cancer. Platinum-refractory disease may respond to a lesser degree. The most important determinant of response was the progression-free interval from first-line chemotherapy. Whether patients recurring after carboplatin plus cyclophosphamide have a greater chance to respond to cisplatin plus ifosfamide or vice-versa cannot be supported by the current data and therefore randomized studies should be performed to this end.

Aged↗
PubMed1997

[Cutaneous hyalinosis: 3 cases].

INTRODUCTION: The authors report three cases of "Hyalinosis cutis et mucosae"; the first and the second case concern two siblings children (brother and sister) while the third is reported on a 42-year-old woman. PRESENTATION OF CASES: The case history and the personal anamnesis, the morphology of the skin lesions, the symptoms indicating laryngeal mucous affection as well as the histopathological picture, are compatible with the "Urbach-Wiethe disease". Furthermore, in the third case, the electron microscopic findings confirm the diagnosis. DISCUSSION: The particularities of the present cases are discussed in connection with the corresponding bibliographical data.

Adult↗
PubMed1996

Diversity among abortion strains of Chlamydia psittaci demonstrated by inclusion morphology, polypeptide profiles and monoclonal antibodies.

Twenty eight C. psittaci abortion strains had been previously classified in to 4 immunologically distinct groups on the basis of cross-protection experiments in a mouse model. To identify the molecular basis of their immunological divergence 4 representative strains were investigated by cellular, molecular and immunological techniques. An identical pattern was obtained by Alul digestion of the amplified major outer membrane protein gene (MOMP) by the polymerase chain reaction (PCR) of the 4 strains. However, inclusion morphology and polypeptide profiles clearly distinguished one strain, named LLG, and its homologous strain POS from the other prototypes by the presence of a unique protein at 26.5 kDa and the absence of a polypeptide at 23 kDa. Six out of 10 monoclonal antibodies (mAbs) raised against abortion strains failed to react with inclusions of the 2 strains. All 6 mAbs reacted with the chlamydial outer membrane complex (COMC). Two of these mAbs, one against the MOMP and one against an antigen at 90 kDa, did not react with immunoblots of LLG and POS. The data provide direct demonstration of the existence of strain variation in the field and classify strains LLG and POS as a distinct C. psittaci serotype 1-subtype. The antigenic diversity among abortion strains should be taken into consideration when designing a subunit vaccine.

Abortion, Veterinary↗
PubMed1994

Lower lid reconstruction with a chondromucosal alar graft and upper lid musculocutaneous flap.

Partial or total lower lid reconstruction implies the repair of three layers: the skin, the tarsus, and the conjunctiva. The method of reconstruction must, therefore, aim at three objectives: ensuring the stability of the lid by repairing the tarsoconjunctival layer, achieving an aesthetic result with the repair of the skin, and taking into consideration the primary role of the upper lid in the ocular protective system. We recommend a musculocutaneous flap, taken from the upper lid, with a single lateral or medial pedicle combined with a chondromucosal alar graft. During the last 10 years, 41 patients were operated on with malignant skin tumors requiring marginal, partial, and total lower lid reconstruction. The results were quite satisfactory from a functional and aesthetic point of view. We noticed two cases of partial flap necrosis and two cases of ectropion needing revision. We believe that the procedure described can be a tool in the armamentarium of the plastic surgeon involved in the field of the orbitopalpebral area.

Eyelid Neoplasms↗
PubMed1992

Immunosuppression in goats by dexamethasone and cyclophosphamide.

The influence of dexamethasone and cyclophosphamide on the goat immune system was investigated. Seven goats, with a previous contact with caprine herpesvirus type 1 (CHV-1), were used. All had been vaccinated with live Mycobacterium paratuberculosis vaccine. Six goats were injected intravenously (i.v.) with dexamethasone daily for 5 days (2.5-4 mg/kg BW per day). Three also received 25 mg/kg BW of cyclophosphamide on day 0. The seventh goat was not treated. Dexamethasone alone caused depression, slight lymphopenia and fall in tuberculin reaction. Dexamethasone plus cyclophosphamide caused a severe clinical reaction, marked leukopenia (lymphopenia and polymorphopenia), fall in tuberculin reaction and significant increase in CHV-1 neutralizing antibody titres. M. paratuberculosis antibody reaction was variable and thus difficult to be assessed. CHV-1 was not isolated.

Animals↗
PubMed1992

[Microsurgical repair after excision of large cancers. Apropos of 14 cases].

The specialty which has benefited the most from the rapid development of reconstructive microsurgery over the last decade, has been plastic surgery. In particular, the authors refer to reconstructive microsurgery after malignant tumor resection. Resections which used to cause serious psychological problems or which required multiple reconstructive procedures, can now be performed as a single stage procedure with good oncological, functional and aesthetic results. This experience concerns the treatment of 14 primary or recurrent malignant tumors of the skin and soft tissues using microsurgical techniques. The free latissimus dorsi musculocutaneous flap was the flap most commonly used. The authors also used the groin flap, the scapular flap, the tensor fasciae latae flap, the dorsalis pedis flap and finally the jejunum combined with the second metatarsus to reconstruct the mandible and the floor of the mouth. Complications consisted of complete necrosis of a dorsalis pedis flap and two revisions were performed for venous thrombosis. With a minimum follow-up of 5 years, one patient has developed a local recurrence and another has developed regional lymph node metastases. The functional and aesthetic results were quite satisfactory. The authors believe that microsurgery is a very valuable technique to treat difficult reconstructive problems.

Humans↗