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Biomedical subjects

D Papadopoulos

Publications and source records attributed to D Papadopoulos.

18 recordsLinked to original sources
PubMed2006

Glass-ceramic materials from electric arc furnace dust.

Electric arc furnace dust (EAFD) was vitrified with SiO2, Na2CO3 and CaCO3 powders in an electric furnace at ambient atmosphere. Vitreous products were transformed into glass-ceramic materials by two-stage heat treatment, at temperatures determined by differential thermal analysis. Both vitreous and glass-ceramic materials were chemically stable. Wollastonite (CaSiO3) was separated from the parent matrix as the dominant crystalline phase, verified by X-ray diffraction analysis and energy dispersive spectrometry. Transmission electron microscopy revealed that wollastonite crystallizes mainly in its monoclinic form. Knoop microhardness was measured with the static indentation test method in all initial vitreous products and the microhardness values were in the region of 5.0-5.5 GPa. Devitrification resulted in glass-ceramic materials with microhardness values strongly dependent on the morphology and orientation of the separated crystal phase.

Ceramics↗
PubMed2005

Global initiative for chronic obstructive lung disease for chronic obstructive pulmonary disease: GOLD opportunity for lung disorders.

BACKGROUND: The purpose of this study was to assess the agreement of asthma and chronic obstructive pulmonary disease (COPD) treatment prescribed by physicians and pulmonologists in comparison to asthma and COPD guidelines and the need of the implementation of COPD guidelines in primary health care physicians. METHODS: Eighty-three asthma patients and 100 COPD patients were chosen and classified in relation to the agreement of their treatment prescribed by a health care physician and that mentioned by global initiative for chronic obstructive lung disease (GOLD) The COPD patients were classified according to their stage of the disease too. RESULTS: Both pulmonologists and primary health care physicians manage asthma patients following asthma guidelines, while great proportion of COPD patients are undertreated by primary health care physicians. The proportion of undertreated COPD patients is decreased as the stage of disease is progressing. CONCLUSIONS: COPD patients mainly are undertreated by primary health care physicians when they are in the primary stages of the disease. The overtreatment of some patients consists of high doses of inhaled steroids prescribed by both pulmonologists, and mainly, primary health care physicians. Therefore, it can be concluded that there is the need of the implementation of COPD guideline by primary health care physicians and the need of COPD patients to be diagnosed in early stages by performing spirometry.

Aged↗
PubMed2003

Medical staff's knowledge of pulse oximetry: a prospective survey conducted in a tertiary children's hospital.

OBJECTIVES: To assess the knowledge of pulse oximetry of senior (SMO) and junior medical officers (JMO) in a tertiary paediatric hospital. METHODS: A 16-item multiple choice questionnaire was administered to SMO and JMO without prior notice or instruction in the area. The questions were completed voluntarily and anonymously, then proctored and collated by the principal investigator. RESULTS: The mean test scores for SMO and JMO were 70 +/- 15% and 65 +/- 13%, respectively (P = 0.06). A significant negative correlation was found between the test scores and the years of paediatric experience with the SMO. CONCLUSIONS: The results of the survey showed there is an insufficiency of knowledge and understanding among medical staff concerning the principles, clinical applications and limitations of pulse oximetry. More emphasis needs to be placed on teaching these principles to ensure quality care for patients.

Australia↗
PubMed1999

Genomic evolution during a 10,000-generation experiment with bacteria.

Molecular methods are used widely to measure genetic diversity within populations and determine relationships among species. However, it is difficult to observe genomic evolution in action because these dynamics are too slow in most organisms. To overcome this limitation, we sampled genomes from populations of Escherichia coli evolving in the laboratory for 10,000 generations. We analyzed the genomes for restriction fragment length polymorphisms (RFLP) using seven insertion sequences (IS) as probes; most polymorphisms detected by this approach reflect rearrangements (including transpositions) rather than point mutations. The evolving genomes became increasingly different from their ancestor over time. Moreover, tremendous diversity accumulated within each population, such that almost every individual had a different genetic fingerprint after 10,000 generations. As has been often suggested, but not previously shown by experiment, the rates of phenotypic and genomic change were discordant, both across replicate populations and over time within a population. Certain pivotal mutations were shared by all descendants in a population, and these are candidates for beneficial mutations, which are rare and difficult to find. More generally, these data show that the genome is highly dynamic even over a time scale that is, from an evolutionary perspective, very brief.

Biological Evolution↗
PubMed1996

Anterior cruciate ligament replacement using part of the patellar tendon as a free graft.

The operative result in 91 patients who had a repair of a ruptured anterior cruciate ligament and replacement with a bone-patellar ligament-bone autogenous graft are analyzed. The average time between initial injury and operation was 2 years. Instability of the knee had been present for 6 months to 6 years and the mean follow up was 4 years. Indications for the intraarticular repair were a positive Pivot shift test and Lachman test and a positive anterior drawer sign at the preoperative examinations while under anesthesia. Seventy percent of the injuries were sports related and the remaining thirty percent injured their knee during work-related activities. Forty-eight percent (44 patients) had an associated meniscal lesion, the majority of which were on the medial side. Eighty percent of the meniscal lesions required partial meniscectomy and 20% were repaired. Eleven percent (10 patients) had an associated chondral lesion while 2 patients had a second degree of chondromalacia of the patella. The results were assessed using the Clancy criteria. Sixty eight percent (62 patients) had an excellent result, 28% (25 patients) very good, and 4 patients fair or good. The Lachman test was negative in 70% of out patients and mildly positive with a firm end point in 30%. The pivot shift test was negative in 71% and mildly positive in 29% of our patients.

Adult↗
PubMed1994

Purification and initial characterization of microsomal epoxide hydrolase from the human adrenal gland.

Microsomal epoxide hydrolase from the human adrenal gland was purified to a high degree of homogeneity in 10% overall yield using sequential chromatography on DE-52, FPLC Mono Q and FPLC Superose columns. The fact that the overall purification was only 7.3-fold indicates that approx. 14% of the total microsomal protein consisted of this enzyme, a uniquely high value. The human adrenal enzyme was found to resemble rat liver microsomal epoxide hydrolase closely in a number of respects, including molecular weight, N-terminal amino-acid sequence and response to low-molecular weight ligands. However, rabbit antibodies directed against human adrenal microsomal epoxide hydrolase crossreacted only weakly with the corresponding rat liver protein. The relatively high levels of microsomal epoxide hydrolase in the human adrenal gland suggest that this enzyme may be of particular importance in this tissue. However, very little cytochrome P-450-catalyzed metabolism of xenobiotics has been demonstrated in the human adrenal and our present results speak against the involvement of microsomal epoxide hydrolase in the steroid metabolism of this gland. Thus, the function of this enzyme in the human adrenal is enigmatic.

Adrenal Glands↗
PubMed1993

The effect of advanced age on the efficacy of radiation therapy for early breast cancer, local prostate cancer and grade III-IV gliomas.

PURPOSE: This study was undertaken to determine the effect of advanced age on radiation therapy outcomes for early breast cancer, local prostate cancer and Grade 3-4 gliomas of the brain. METHODS AND MATERIALS: Radiation therapy outcomes for three malignancies (N = 1,401) were determined for a geriatric cancer population defined as 70 years of age or older and compared to a non-geriatric cancer population defined as less than 70 years of age. The three patient groups studied were: (a) primary breast cancer patients with clinical Stage I or II disease treated with lumpectomy and radiation therapy (N = 994), (b) local prostate cancer patients with Stage A2, B, or C disease treated with radical radiation therapy (N = 294), and (c) patients with Grade 3-4 gliomas of the brain treated with high dose radiation therapy (N = 113). RESULTS: For Stage I and II breast cancer, there was no statistically significant difference in the overall 10-year survival rates (63% vs. 73%), 10-year cause-specific disease-free survival rates (70% vs. 63%), and 10-year local breast recurrence free survival rates (76% vs. 79%) comparing the geriatric cancer population to the non-geriatric cancer population. For local prostate cancer, there was no statistically significant difference in the 10-year survival rates (38% vs. 41%) or in the 10-year cause-specific disease-free survival rates (58% vs. 52%) in the geriatric population compared with the non-geriatric population. On the other hand, the use of high dose radiation therapy for malignant gliomas resulted in statistically significant inferior 1-year (18% vs. 38%) and 2-year (0% vs. 10%) survival rates for the geriatric population versus the non-geriatric population. CONCLUSION: This study strongly supports the use of standard radiation therapy programs for early breast and prostate cancer patients age 70 years or more. However, our study raises questions about the efficacy of radiation therapy in patients over the age of 70 years with Grade 3-4 gliomas.

Age Factors↗
PubMed1992

Levels of cytochrome P-450, steroidogenesis and microsomal and cytosolic epoxide hydrolases in normal human adrenal tissue and corresponding tumors.

The levels of microsomal cytochrome P-450, steroidogenesis and microsomal and cytosolic epoxide hydrolase activities in normal human adrenal tissue (obtained from adult kidney transplant donors and autopsy material) and corresponding hyperplasia, adenomas and carcinomas (surgical biopsies) were determined. The increased steroid production demonstrated by most of the pathological tissue samples examined here was associated with either an unchanged or dramatically decreased specific microsomal content of cytochrome P-450. Furthermore, specific microsomal epoxide hydrolase activity was also found to be reduced in adrenocortical carcinomas, while the corresponding cytosolic activity was also decreased in at least two of these carcinomas. It is of interest to note in this connection that the level of microsomal epoxide hydrolase in slightly atropic adrenal cortex surrounding adrenocortical carcinomas was also found to be reduced. This would indicate that despite its appearance, this surrounding tissue is not normal in all respects. Thus, adrenocortical carcinomas fit into the common pattern in that their specific contents of microsomal cytochrome P-450 are dramatically decreased, but the simultaneous decrease in their microsomal epoxide hydrolase activity is more unusual.

Adrenal Cortex↗
PubMed1990

Radiation therapy for ductal carcinoma in situ of the breast.

The optimal treatment for ductal carcinoma in situ (DCIS) of the breast is undefined. At three Connecticut hospitals 1) Yale-New Haven Hospital, New Haven; 2) Uncas-on-Thames Hospital, Norwich; 3) Norwalk Hospital, Norwalk, breast conservation therapy with lumpectomy followed by radiation therapy (RT) has been offered to women with DCIS as an alternative to mastectomy. From 1974 through 1987, 60 women with DCIS have been treated with RT. With a minimum evaluable follow-up of two years, a maximum follow-up of 15 years, and a median follow-up of 3.6 years, there have been no cancer-related deaths in the 60 patients. Four of the 60 patients (6.7%) developed a local breast recurrence but were salvaged with further surgical therapy (three patients with mastectomies and one patient with repeat lumpectomy). Only one patient (2%) has died of nonmalignant disease and the remaining 59 patients (98%) survived cancer-free. The five-year actuarial breast recurrence-free rate was 95%. These results suggest that breast conservation therapy with RT is a viable treatment option for women with DCIS.

Adult↗
PubMed1985

Subcellular distribution, catalytic properties and partial purification of epoxide hydrolase in the human adrenal gland.

Epoxide hydrolase in human adrenal gland was characterized with respect to catalytic properties and subcellular distribution. With human adrenal microsomes and the substrates styrene-7,8-oxide, cis-stilbene oxide, estroxide and androstene oxide the specific activities were between 1.9 and 19.0 nmol/min/mg protein. With styrene-7,8-oxide as substrate the apparent Km-value was 0.98 mM and the pH optimum was 9.2. Subcellular fractionation revealed that the bulk of the activity was confined to the endoplasmic reticulum. Different compounds known to influence rodent microsomal epoxide hydrolase activity were also tested on the human adrenal enzyme. 1,1,1-Trichloropropene-2,3-oxide (TCPO) and cyclohexene oxide (CHO) inhibited the activity while benzil and clotrimazole stimulated the activity. Partial purification of human adrenal epoxide hydrolase indicates that its molecular weight is about 51 000 and that its concentration relative total protein in the human adrenal microsomes is about 10%.

Adrenal Glands↗
PubMed1984

Metabolism of xenobiotics in the human adrenal gland.

The capacity of the human adrenal gland to metabolize various xenobiotics was investigated. Adrenal microsomal and mitochondrial preparations showed a maximal absorption at 450 nm for dithionite-reduced cytochromes in the presence of carbon monoxide. Occasionally, absorption maxima at 448 nm were observed with both microsomal and mitochondrial preparations. Microsomal and mitochondrial cytochrome P-450 (448) concentrations were found to be 0.34 and 0.23 nmol/mg protein, respectively. In spite of the high microsomal cytochrome P-450 levels neither the hydrocarbons, benz[a]pyrene (BP) and 7,12-dimethylbenz[a]anthracene (DMBA), nor a variety of other substrates were metabolized to any measurable extent. In contrast, microsomal epoxide hydrolase and soluble glutathione transferase activities were high. The results may explain the low incidence of adrenal cancer in man.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

Ultrastructure, organization and cytochemistry of cytoplasmic crystalline inclusions in Origanum dictamnus L. leaf chlorenchyma cells.

In the cytoplasm of chlorenchyma cells in primary Origanum dictamnus leaves, rectangular prism-like crystals occur, which, as shown by pepsin digestion, are proteinaceous. In sections they usually show either a square lattice or striations running parallel to the short or long axis. In both cases the interspacings are estimated to be about 100 A, suggesting that the arrangement of the crystallographic planes possesses tetragonal symmetry. High magnifications of the crystalline inclusions together with analysis of their diffraction patterns showed that the striations are composed of double helices of protein macromolecules. In leaves 3-4 mm long, eroded crystals are often observed. When leaves are larger than 5 mm, no crystalline bodies can be identified in chlorenchyma cells. It is possible that they represent a storage form of protein, which is used later by the developing cells.

Chloroplasts↗
PubMed1982

Metabolism of polycyclic aromatic hydrocarbons and covalent binding of metabolites to protein in rat adrenal gland.

The metabolism of the carcinogenic and adrenocorticolytic polycyclic aromatic hydrocarbon 7,12-dimethylbenz(a)anthracene in rat adrenals was investigated. Both 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene, which also is a well-known carcinogen but has no short-term effects on rat adrenals, appear to be metabolized by one common type of cytochrome P-450-dependent monooxygenase localized in the endoplasmic reticulum. Studies of the kinetic properties of this cytochrome P-450 reveal that the Km values for 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene are lower than 3 microM. Identification of metabolites indicates that, with both 7,12-dimethylbenz(a)anthracene and benzo(a)pyrene, phenols and diols were formed the relative rates of formation of which were markedly influenced by the expoxide hydrase inhibitor cyclohexane oxide, suggesting that epoxides are intermediate metabolites. Added or endogenous microsomal glutathione S-transferase B had little or no effect on the distribution of metabolites. A rather selective binding of metabolites of 7,12-dimethylbenz(a)anthracene to soluble and microsomal proteins was demonstrated. The adrenal cytochrome P-450 involved in the conversion of these polycyclic aromatic hydrocarbons appears to be unrelated to those responsible for the synthesis of mineralocorticoids and glucocorticoids from cholesterol. Among androgens and estrogens, estradiol proved to be the most inhibitory steroid, suggesting a role of the hydrocarbon-metabolizing cytochrome P-450 in estrogen biosynthesis. However, no such function could be demonstrated conclusively. The metabolite patterns and the effects of nonsteroid inhibitors of liver monooxygenases, e.g., alpha-naphthoflavone, SU 9055, and ellipticine, suggest that the properties of this cytochrome P-450 resemble those of the 3-methyl-cholanthrene-inducible cytochrome P-488 from rat liver.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1977

HLA-B27 frequency in Greek patients with acute anterior uveitis.

The histocompatibility antigen HLA-B27 was identified in 12 out of 33 patients with acute non-granulomatous anterior uveitis. This is a frequency of 36.36%, compared with 4.72% in controls. Seven patients had in addition evidence of systemic disease, including ankylosing spondylitis, sacroiliitis, Reiter's disease, Still's disease, and rheumatoid arthritis. Five of these were HLA-B27 positive, which suggests that the uveitis in many of these cases has a similar aetiology to the uveitis in those with rheumatic disease. It appears that the more severe cases of acute anterior uveitis are related more frequently to the presence of HLA-B27.

Acute Disease↗
PubMedDate not supplied

Growth delay effect of combined interstitial hyperthermia and brachytherapy in a rat solid tumor model.

The rat mammary AC33 solid tumor model was used to investigate the efficacy of interstitial hyperthermia and/or brachytherapy. Subcutaneous flank tumors were heated with an interstitial microwave (915 MHz) antenna to a temperature of 43 +/- 0.5 degrees C for 45 min for two treatments, three days apart, and/or implanted with Ir-192 seeds for three days (-25 Gy tumor dose). Following treatments, tumors were measured 2 to 3 times per week. Hyperthermia alone produced a modest delay in tumor volume regrowth, while brachytherapy was substantially more effective. The combination produced a improvement in tumor regrowth delay compared to brachytherapy alone.

Animals↗