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Biomedical subjects

G Theodoropoulos

Publications and source records attributed to G Theodoropoulos.

At least 19 recordsLinked to original sources
PubMed2000

Seasonal patterns of strongyle infections in grazing sheep under the traditional production system in the region of Trikala, Greece.

Ten 4-month-old female sheep of the Karagouniko dairy breed were used to monitor the seasonal fluctuations of strongyle infections in sheep during the first year of grazing under the traditional production system in the region of Trikala, Greece, where control of nematodes is currently based exclusively on the frequent use of anthelmintics which might contribute to the appearance of anthelmintic resistance. The sheep grazed communal pasture plots and did not receive any anthelmintic treatment during the entire study period. Faecal egg counts (epg), plasma pepsinogen levels, blood values, and genera of parasitic strongyles recovered from coprocultures were recorded monthly. Mean epg for strongyle-type eggs were significantly higher during summer. Mean plasma pepsinogen levels were significantly higher during spring and summer. The genera of parasitic strongyles recovered from the faecal cultures were Haemonchus, Ostertagia, Trichostrongylus, Cooperia, Nematodirus, Oesophagostomum, and Chabertia. The percentages of larvae for Haemonchus, Ostertagia, Cooperia, and Oesophagostomum were significantly higher during winter. The percentages of larvae for Trichostrongylus were significantly higher during summer. During summer, levels of RBC, HGB, and HCT were depressed and levels of MCV, MCH, and MCHC were elevated. Mean epg for strongyle-type eggs had a significant inverse correlation with RBC, HGB, HCT, and positive correlation with MCH, MCHC, and percentages of eosinophils in differential leucocyte counts. The seasonal pattern of infection observed in the present study indicates that it is possible to decrease the number of treatments to one per year, thus, reducing the possibility for the appearance of anthelmintic resistance.

Animals↗
PubMed2000

Infectivity, predilection sites, and freeze tolerance of Trichinella spp. in experimentally infected sheep.

A total of 36 sheep in groups of 4 were inoculated with 9 isolates of Trichinella and euthanized after 10 weeks. Thereafter, numbers of muscle larvae were determined in 13 different muscles/muscle groups. Muscle larvae were found in high numbers in all four sheep inoculated with T. spiralis, in lower numbers in two sheep inoculated with T. pseudospiralis (USA isolate), and in very low numbers in one sheep inoculated with T. pseudospiralis (USSR isolate) and one inoculated with T. britovi. In infections of high and moderate larval intensity, predilection sites of T. spiralis were the masseter muscles, the tongue, and the diaphragm and those of T. pseudospiralis were the masseter muscle and the neck. In low-intensity infections, muscle larvae were detected only in the diaphragm or in pooled muscle samples. For evaluation of the freeze tolerance of the different Trichinella species in sheep-muscle tissue, samples taken from the filet were stored at +5 degrees, -5 degrees, and -18 degrees C, respectively. After exposure for 1 and 4 weeks the tissue was digested and the released larvae were inoculated into mice for determination of the reproductive capacity index (RCI). Larvae of both T. spiralis and T. pseudospiralis survived freezing at -5 degrees and -18 degrees C for 4 weeks.

Animals↗
PubMed2000

A digital image analysis and neural network based system for identification of third-stage parasitic strongyle larvae from domestic animals.

A competitive learning vector quantization artificial neural network (ANN) was trained to identify third-stage parasitic strongyle larvae from domestic animals on the basis of quantitative data obtained from processed digital images of larvae. For this reason, various quantitative features obtained from processed digital images of larvae were tested as to whether they are variant or invariant to the shape taken by the motile larvae during image recording. A total of 255 images of 57 individual larvae in various shapes belonging to five genera were recorded. Following image processing, 16 features were measured, of which seven were selected as invariant to larva shape. By trial and error, two of those features, 'area' and 'perimeter', along with the quantitative features used in conventional identification, 'overall body length', 'width' and 'extension of sheath' (tip of larva to tip of sheath), were used as an effective training data set for the ANN. This ANN coupled with an image analysis facility and a knowledge relational database became the basis for developing a computer-based larva identification system whose overall identification performance was 91.9%. The advantages of this system are its speed and objectivity. The objectivity of the system is based on the fact that it is not subject to inter- and intra-observer variability arising from the user's profile of competency in interpreting subjective and non-quantifiable descriptions. The limitations of the system are that it cannot handle raw images but only data extracted from images, its performance depends on the reliability of the input vectors used as training data for the ANN, and its use is restricted only to well-equipped laboratories due to its requirement for expensive instrumentation.

Animals↗
PubMed2000

Nematode parasite control practices of sheep and goat farmers in the region of Trikala, Greece.

Information concerning worm control practices of sheep and goat farmers in the region of Trikala (central Greece) was collected through a questionnaire survey by visiting farms and interviewing farmers. Questionnaires from 57 farmers residing in 23 rural communities were collected. Anthelmintics were used by 89% of the farmers. On average, lambs, kids and goats were treated once annually, while sheep were treated either once or twice annually. Only 2% of farmers reported treatment of animals with anthelmintics when moving to new pastures. The most common broad-spectrum anthelmintics used were those belonging to the benzimidazoles and probenzimidazoles. Fifty nine percent of the farmers used the same anthelmintic group for 3 or more years and 34% used two or more anthelmintic groups in the same year. Almost all farmers reported estimating live weights for calculating anthelmintic doses through visual perception on the basis of an average weight (96%). Tablets and boluses were the most preferred anthelmintic formulation used by 96% of farmers. The selection of an anthelmintic was based for 58% of farmers on recommendation by a veterinarian and for 39% of farmers on the cost of the drug. The most common occasions for deworming the animals were at turn out (86%) and after parturition (31%). Only 6% of farmers reported deworming new animals before introducing them onto the farm. Farmers preferred to seek information about the use of anthelmintics and worm control strategies from veterinarians (63%) and other farmers (37%).

Animal Husbandry↗
PubMed1998

Seasonal variation of gastrointestinal nematodes of sheep in the region of Joannina, Greece.

Parasitological and growth studies on two groups of naturally infected sheep, with or without anthelmintic treatment, from the age of 3 months to 2 years were carried out in the region of Joannina, Greece. A split-plot design was used so that each group, consisting of seven pure-bred Boutsiko and seven cross-bred Boutsiko with Karamaniko (F1) lambs, grazed separate parasitologically equivalent pasture plots. Faecal egg counts, pasture larval counts, plasma pepsinogen levels and live weight were recorded monthly. Infective larvae on each pasture plot increased during autumn and winter. Mean faecal egg counts for strongyle-type eggs were higher in the non-treated than the treated group and in the cross than the pure-bred sheep. Mean plasma pepsinogen levels were higher during autumn of the second year of the study. The results of the study suggest that the factors affecting the epidemiology of gastrointestinal nematodes of naturally infected sheep during grazing in the region of Joannina include anthelmintic treatment, host genotype and season, while the effectiveness of anthelmintic treatment in this study, as applied in the area, was questionable.

Age Factors↗
PubMed1995

Evaluation of overexpression of p53 tumor suppressor protein in superficial and invasive transitional cell bladder cancer: comparison with DNA ploidy.

OBJECTIVES: p53 tumor suppressor gene is considered to play a significant role in carcinogenesis. Mutations in the p53 are the most frequent genetic abnormalities encountered in human malignancies. Our aim was to investigate the expression of p53 oncoprotein in superficial and invasive transitional cell bladder cancer (TCC) as well as its correlation with established prognostic factors, such as histologic grade, tumor stage, DNA content, and survival. METHODS: Forty-five patients with superficial TCC (Ta-T1) and 42 with invasive TCC (T2-T4) were included in our study. Material from transurethral biopsy was examined using an immunohistochemical method and the monoclonal antibody Pab 1801. RESULTS: p53 tumor suppressor protein was overexpressed in 48.3% of TCC cases and more frequently in invasive than superficial TCCs (P = 0.03) and undetectable in the tumor adjacent to normal tissue. p53 positivity was related to the degree of differentiation and with the stage of the disease of invasive TCCs (P = 0.03 and P = 0.004, respectively), whereas no statistical significance was documented for superficial TCCs. Moreover, p53 overexpression demonstrated a statistical significance with DNA ploidy in superficial Ta-T1 tumors (P = 0.04) and was suggestive in invasive T2-T4 tumors (P = 0.08). There was no correlation of recurrence related to p53-positive superficial tumors (P = 0.29). Patients with p53-positive invasive TCCs showed statistically significant worse survival (P = 0.007), but in multivariate analysis, p53 positivity is not independently related to poor overall survival (P = 0.30). When we combined ploidy and p53 status, we realized that the subset of patients with aneuploidy and p53 positivity had the worst prognosis (P = 0.008). CONCLUSIONS: The results suggest the involvement of p53 protein as a late event in bladder carcinogenesis. p53 does not seem to be a prognostic marker for recurrences of superficial tumors and is not independently related to survival. The aneuploidy of tumors correlates with the p53 positivity in bladder cancer. The combined expression of aneuploidy and p53 positivity in invasive tumors has strong association with the survival of patients.

Adult↗
PubMed1995

[Abdominal actinomycosis in tubo-ovarian abscess].

Diagnosis of actinomycosis as a specific infection is rather difficult. By a case report it is described that preoperative diagnostics and intraoperative situs do not always exactly clarify the situation. In most cases the definite diagnosis can only be achieved by histological findings followed by an adequate therapy.

Abdominal Abscess↗
PubMed1994

A veterinary anatomy tutoring system.

A veterinary anatomy tutoring system was developed by using Knowledge Pro, an object-oriented software development tool with hypermedia capabilities, and MS Access, a relational database. Communication between them is facilitated by using the Structured Query Language (SQL). The architecture of the system is based on knowledge sets, each of which covers four different descriptions of an organ, namely gross anatomy (general description), gross anatomy (comparative features), histology, and embryology, which constitute the knowledge units. These knowledge units are linked with three global variables that define the animals, the topographies, and the system to which this organ belongs, creating three data-bases. These three data-bases are interrelated through the organ field in order to establish a relational model. This system allows versatility in the student's navigation through the information space by offering different modes for information location and presentation. These include course mode, review mode, reference mode, dissection mode, and comparison mode. In addition, the system provides a self-evaluation mode.

Anatomy, Veterinary↗
PubMed1994

Parasitology tutoring system: a hypermedia computer-based application.

The teaching of parasitology is a basic course in all life sciences curricula, and up to now no computer-assisted tutoring system has been developed for this purpose. By using Knowledge Pro, an object-oriented software development tool, a hypermedia tutoring system for teaching parasitology to college students was developed. Generally, a tutoring system contains a domain expert, a student model, a pedagogical expert and the user interface. In this project, particular emphasis was given to the user interface design and the expert knowledge representation. The system allows access to the educational material through hypermedia and indexing at the pace of the student. The hypermedia access is facilitated through key words defined as hypertext and objects in pictures defined as hyper-areas. The indexing access is based on a list of parameters that refers to various characteristics of the parasites, e.g. taxonomy, host, organ, etc. In addition, this indexing access can be used for testing the student's level of understanding. The advantages of this system are its user-friendliness, graphical interface and ability to incorporate new educational material in the area of parasitology.

Artificial Intelligence↗
PubMed1993

A multimedia relational database program for parasite identification.

Parasites are responsible for human and animal diseases causing suffering and economic loss all over the world. Parasite identification is an important step in treating and combating parasitic diseases. This task can be assisted by computer programs. Until now computer based systems for parasite identification were fixed tree-decision programs which had no updating or expansion capacity and no ability for optimal searching algorithms. A new program was developed by using a multimedia relational database management system with a graphical environment. This program can incorporate expert knowledge in its relational structure and identify the parasites by using its structured query language. Also, the program has the ability for partial identification by presenting the parasites that match the available incomplete information. In addition, the program can handle images and sound to present pictures and relevant information on the identified parasites. The advantages of the new program are its friendly graphical user interface and its unlimited capacity to incorporate new knowledge.

Algorithms↗
PubMed1992

Serum protein groups (Hp, GC, C3) in patients with gastric carcinoma.

The phenotypes and gene frequencies of 3 serum protein systems (Hp, GC and C3) were studied in 114 consecutive patients from all over Greece with gastric carcinoma. Healthy Greeks studied previously in our Department served as controls. No significant differences were found between patients and controls concerning Hp. Significant differences were found in the GC and C3 systems; GC 2-1 and C3F phenotype as well as C3*F gene frequencies were significantly higher in patients than in controls.

Adult↗
PubMed1992

Ranitidine and antacids in the prevention of duodenal ulcer relapse in Greece.

The present study was undertaken to compare the efficacy of ranitidine 150 mg/nocte with that of antacids taken "on demand" in the prevention of recurrence of duodenal ulcer (DU). Two groups (A, B) of patients with DU recently healed by ranitidine or antacids were studied. Patients of Group A (110) healed by ranitidine were put on maintenance treatment with ranitide, and patients of Group B (32) healed by antacids were given antacids "on demand" for a period of one year. Endoscopy was performed at the end of the 6th and 12th months, as well as whenever symptoms appeared. Patients were followed up clinically at 2-month intervals. Relapse rates of 11% (group A) and 34% (group B) were found at the end of the 6th month, (p less than 0.005), while the total relapse rates at the end of the 12th month were 19% and 47%, respectively (p less than 0.005). Recurrences were asymptomatic in 62% (Group A) and 27% (Group B) of patients. No significant side effects were observed. It is concluded that ranitidine 150 mg nocte is significantly superior to antacids "on demand" as far as the recurrence of DU is concerned.

Adult↗
PubMed1991

A compiled computer program for assisting the diagnosis of gastrointestinal helminths of humans and animals.

A compiled computer program for assisting the diagnosis of gastrointestinal helminths in fecal examinations of humans and animals is described. The characteristics of this program which distinguish it from previous similar programs are that it does not require specific software, it does not need a lot of computer memory, and it covers both humans and animals, making it easier to use.

Animals↗
PubMed1990

Change in the isoenzyme composition of acid phosphatase in murine peritoneal macrophages exposed to or infected with Trypanosoma cruzi.

The effect of infection with Trypanosoma cruzi on the activity and isoenzyme composition of acid phosphatase within individual murine peritoneal macrophages maintained in vitro was studied. Concentrations of acid phosphatase activity and number of intracellular parasites were quantitated by using a computer-assisted cytospectrophotometry system. Changes in the isoenzyme composition of macrophages during infection with T. cruzi were detected by comparing the patterns of acid phosphatase levels between macrophages treated in the absence and presence of an enzyme inhibitor. It was observed that the concentration levels of acid phosphatase activity in macrophages did not change significantly by infection with T. cruzi. Also, the concentration levels of acid phosphatase activity did not change in macrophages uninfected but exposed to T. cruzi. On the other hand, the isoenzyme composition of acid phosphatase did change in macrophages exposed to or infected with T. cruzi. These results demonstrate that Trypanosoma cruzi affects the acid phosphatase composition of macrophages.

Acid Phosphatase↗
PubMed1990

Therapeutic effect of the triazole Bay R 3783 in mouse models of coccidioidomycosis, blastomycosis, and histoplasmosis.

A new triazole, Bay R 3783, was compared with ketoconazole, itraconazole, and fluconazole, which were given via the alimentary tract at three dosages, and amphotericin B, which was given at 1 mg/kg intraperitoneally, in murine models of the systemic mycoses coccidioidomycosis, histoplasmosis, and blastomycosis. In a pulmonary coccidioidomycosis model, Bay R 3783, fluconazole, and itraconazole were essentially equally efficacious and more active than ketoconazole in protecting mice against death; but they were inferior to amphotericin B. In a short-term organ load experiment, Bay R 3783 and amphotericin B were equally effective and were more effective than the other drugs in reducing the amount of Coccidioides immitis in the lungs. Against meningocerebral coccidioidomycosis, Bay R 3783, itraconazole, and fluconazole at 25 mg/kg and amphotericin B prevented death only during therapy, with mortalities ensuing shortly thereafter. In mice with systemic histoplasmosis, Bay R 3783 and itraconazole at 25 mg/kg and amphotericin B prevented death in all mice through a 44-day observation period. Clearance of Histoplasma capsulatum from organs was similar in mice treated with Bay R 3783 and itraconazole; this clearance was greater than that in mice treated with ketoconazole and fluconazole but less than that in mice treated with amphotericin B. In mice with systemic blastomycosis, Bay R 3783 at 25 mg/kg yielded 90% survivors at 60 days, which was greater than that achieved with amphotericin B (60%) or itraconazole (30%). Clearance of Blastomyces dermatitidis from the lungs was greatest with Bay R 3783, followed by that with amphotericin B, itraconazole, fluconazole, and ketoconazole, in that order. Therefore, Bay R 3783 showed effectiveness comparable to or exceeding those of itraconazole and fluconazole and exceeding that of ketoconazole against these systemic mycoses in mice.

Animals↗
PubMed1989

Decrease of acid phosphatase activity in murine peritoneal macrophages infected with Leishmania donovani.

The effect of infection with Leishmania donovani on the activity and isoenzyme composition of acid phosphatase within individual murine peritoneal macrophages maintained in vitro was studied. Concentrations of acid phosphatase activity and number of intracellular parasites were quantitated using a computer-assisted cytospectrophotometry system. Changes in the isoenzyme composition of macrophages during infection with L. donovani were detected by comparing the patterns of acid phosphatase levels between macrophages treated in the absence and presence of an enzyme inhibitor. It was observed that the concentration levels of acid phosphatase activity in macrophages were decreased significantly by infection with L. donovani. An inverse relation existed between concentration of acid phosphatase activity and the number of intracellular L. donovani. Reduced concentrations of acid phosphatase activity were also observed in macrophages uninfected but exposed to L. donovani. The isoenzyme composition in macrophages did not change during the course of infection with L. donovani. These results demonstrate that L. donovani reduces the acid phosphatase activity of macrophages.

Acid Phosphatase↗
PubMed1989

Computer-assisted diagnosis of gastrointestinal helminths of domestic and experimental animals.

A 'user-friendly' interactive computer program written in BASIC with the objective of assisting the species identification of common gastrointestinal parasites of domestic and experimental animals is described. The computer program operates by prompting the user to select a morphological description from a set of presented descriptions that best fits the observed parasite. Depending on the user's response, the program presents another set of morphological descriptions from which the user must choose again, and so on, until the program concludes with the species of the parasite. A useful feature of this program is the option for the user to go back at any time and see the previous set of descriptions. This option allows the user to choose another description if (s)he thinks that the previous choice was not the correct one.

Animals↗