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Biomedical subjects

C Constantinides

Publications and source records attributed to C Constantinides.

At least 37 records · Page 2Linked to original sources
PubMed1995

PBM: a software package to create, display and manipulate interactively models of small molecules and proteins on IBM-compatible PCs.

The PBM package was developed to create, display and conveniently manipulate protein and small molecule structures on IBM-compatible microcomputers. It consists of four modules: CREATE, SPHERE, RIBBON and CONVERT. CREATE includes commands to create or alter ('mutate') the primary and subsequently the tertiary structure of a given peptide or protein by defining phi and psi angles of residues at will, options to add, delete or alter atoms in a structure, utilities to choose easily between the most common rotamers of amino acid residue sidechains and options to analyse in various ways a protein conformation. SPHERE provides for an interactive manipulation of structures containing up to 2700 atoms which can belong up to six different molecules. All manipulations can be made with the use of an ordinary mouse, by choosing from a variety of pull-down menus. Three types of models can be implemented to display molecules on the computer screen or the plotter: skeletal, solid space-filling and wireframe space-filling models. RIBBON creates ribbon models of proteins and allows for a limited variety of interactive manipulations. CONVERT is a file converter, which is capable of converting files of atom coordinates of literally any format to Brookhaven Data Bank format files. The package produces very good results for protein molecules of reasonable sizes, both in terms of graphics quality and speed of operations, on an 80486 IBM PC-compatible machine equipped with a 1 MByte VGA display card and a colour VGA monitor, which is a recommended configuration.

Computer Graphics↗
PubMed1995

Epithelial differentiation antigens and epidermal growth factor receptors in transitional cell bladder carcinoma: correlation with prognosis.

Epithelial differentiation antigens have been correlated with morphologic differentiation of neoplastic urothelium. Moreover, epidermal growth factor, which is a polypeptide regulating growth and differentiation of normal and neoplastic cells, is found in high concentrations in the urine while its receptors (EGFR) have been identified in bladder tumors. The aim of this study was to investigate the immunohistochemical expression of cytokeratin, epithelial membrane antigen (EMA), CEA and EGFR in transitional cell bladder carcinomas (TCC) and to define any correlation of their expression with tumor grade, stage and patient survival. Twenty-four biopsy specimens obtained from patients with TCC were studied retrospectively. There were 23 men and 1 woman with a mean follow-up of 64 months. Eight biopsy specimens, which represented tumor recurrences of 4 patients, were also included in our material. The immunohistochemical avidin-biotin complex method was performed on paraffin sections for the detection of cytokeratin and EGFR with monoclonal antibodies as well as CEA with a polyclonal antibody. Cytokeratin was detected in 83.5% of the TCC, EMA in 62% and CEA in 70%. The expression of the epithelial differentiation antigens in TCCs was heterogenous, showing an increased incidence in high-grade and high-stage TCC. The CEA expression in TCC demonstrated a statistically significant correlation with patient survival (p < 0.02). EGFR was detected in 50% of the TCC. Although not statistically significant, a trend was found for a higher percentage of EGFR detection in high-grade TCC. EGFR expression was significantly associated with tumor stage and patient survival (p < 0.01 and p < 0.04, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Clinical implication of neuroendocrine differentiation in prostatic adenocarcinomas.

Specimens from 75 cases of prostatic adenocarcinoma of different M.D. Anderson degrees of malignancy were stained immunohistochemically for neuron-specific enolase (NSE), prostatic specific antigen (PSA) and prostatic acid phosphatase (PAP). None of these tumors presented on hematoxylineosin sections any features suggesting neuroendocrine differentiation; nevertheless, 18.7% of the tumors were at least focally NSE positive. Because of the synchronous antigenic expression of the NSE-positive cells to PSA and PAP, the authors suggest that prostatic exocrine and neuroendocrine cells derive from a common precursor stem cell. The possibility of a more aggressive biological behavior of these tumors in comparison to the conventional carcinomas is discussed. The probable clinical necessity for a combined therapeutic approach is also investigated.

Acid Phosphatase↗
PubMed1992

Left ventricular ejection fraction and volumes calculated from dual gated SPECT myocardial imaging with 99Tcm-MIBI.

Dual gated (DG) cardiac single photon emission computed tomographic (SPECT) studies at end-diastole (ED) and end-systole (ES) were acquired in 27 ischaemic heart disease (IHD) patients after intravenous injection of 555-740 MBq 99Tcm-MIBI. Acquisition parameters were: 180 degrees from LPO to RAO, 32 projections, 64 x 64 matrix, 75 cardiac beats per projection, 80 ms at ED and 80 ms at ES for each cardiac cycle. A computer program was developed to calculate the ED and ES left ventricular (LV) volumes and LV ejection fraction (EF). The computational approach is interactive, semi-automatic and iterative with built-in visual quality control. Short axis slices are used with corresponding ED and ES slices processed as pairs from apex to base. Left ventricular cavity pixels are identified and summed on a slice-by-slice basis. Myocardial pixels are similarly identified. The computed LVEF and ED and ES volumes have been correlated with those from contrast ventriculography (CV). The mean calculated EF for 27 patients was 53.6 +/- 10.7% from DG SPECT versus 55.3 +/- 12.1% from CV (NS). The EF linear correlation coefficient was r = 0.97.

Gated Blood-Pool Imaging↗
PubMed1992

Silver-binding nucleolar organizer regions in benign and malignant prostatic lesions.

Thirty-six transvesical or transurethral prostatectomy cases were selected from the histopathology files of the Laiko General Hospital. Among the 36 cases, there were 10 with benign prostatic hyperplasia (8 patients having distinct areas of adenosis) and 26 cases of prostatic adenocarcinoma (6 grade I, 13 grades II and III and 7 grade IV carcinomas). From each case, silver-binding nucleolar organizer regions (AgNORs) have been counted in sections of routinely processed paraffin-embedded tissue blocks. The mean AgNOR count per case was calculated. For the cases of prostatic hyperplasia, the mean AgNOR count was found to be 2.95 +/- 0.42, for adenosis 3.45 +/- 0.56, for grade I adenocarcinoma 4.97 +/- 0.74, for grades II and III 7.31 +/- 0.81 and for grade IV adenocarcinomas 11.41 +/- 1.68. This difference in the mean AgNOR count was found to be of statistical significance (p < 0.001) between adenosis and grade I adenocarcinomas and between grade II and III and grade IV adenocarcinomas. It appears that AgNOR counting may prove to be of benefit in differentiating between some benign and malignant prostatic lesions and that it might provide information concerning the biological behavior of prostatic adenocarcinomas.

Adenocarcinoma↗
PubMed1991

Ureaplasma urealyticum and infected renal calculi.

In a group of 41 patients with infection lithiasis, the presence of Ureaplasma urealyticum in urine and in the calculi was investigated. A control group of 27 patients with metabolic lithiasis was simultaneously evaluated. Ureaplasma urealyticum was detected in a total of 10 patients with infection lithiasis. In 7 of those patients, U. urealyticum was the only urease producing microorganism detected, while in the remaining 3 it was detected along with common bacteria. We believe that U. urealyticum may be considered as a possible causative factor of infection lithiasis.

Adolescent↗
PubMed1991

Accuracy of magnetic resonance imaging compared to computerized tomography and renal selective angiography in preoperatively staging renal cell carcinoma.

During 1986 and 1987, 47 patients with renal cell carcinoma were evaluated preoperatively with CT, angiography and MRI. The preoperative tumor stage (T), lymph node metastases and venous involvement determined with the three methods were compared to the operative and histopathological findings. For T stage, angiography proved less accurate (54%) than CT (64%) or MRI (63%). MRI was found to be superior to CT in assessing lymph nodes, with an overall accuracy of 89% and sensitivity of 100% compared to 77 and 60%, respectively, of CT. For venous involvement CT was overall more accurate (74%) than angiography (65%) or MRI (63%). All three methods expressed a low sensitivity (between 31 and 41%) and a high specificity (between 95 and 100%) for detecting venous involvement. The minimal advantages of MRI compared to its high cost do not justify its routine use. CT remains the method of choice in staging preoperatively renal cell carcinoma.

Angiography↗
PubMed1990

Segmental analysis of SPECT 99mTc-methoxy isobutyl isonitrile and 201Tl myocardial imaging in ischaemic heart disease.

To study the potential usefulness of 99mTc-methoxy isobutyl isonitrile (99mTc-MIBI) as a substitute for 201Tl in assessing patients with ischaemic heart disease, 24 patients underwent 1 day rest and exercise 99mTc-MIBI single photon emission computerised tomography (SPECT) 1 week after SPECT exercise 201Tl. All patients were catheterized within 1 month after myocardial imaging. In 17 patients, resting first pass radionuclide angiography (FPRNA) was performed with 99mTc-MIBI. The heart to lung ratio for 99mTc-MIBI and 201Tl was calculated both at rest and exercise. The segmental analysis for myocardial perfusion reveals that 87/96 segments (91%) were correctly classified by SPECT 201Tl and 84/96 segments (88%) were correctly classified by 99mTc-MIBI. A significant correlation was present between LVEF measured by 99mTc-MIBI FPRNA and contrast ventriculography (r = 0.85, P less than 0.0001). The heart to lung ratio both at rest and exercise for 99mTc-MIBI is significantly higher than 201Tl (P less than 0.01 and less than 0.001 respectively). We conclude that 99mTc-MIBI is a promising agent for simultaneous evaluation of myocardial perfusion and cardiac function.

Contrast Media↗
PubMed1990

Acute prostatitis: which antibiotic to use first.

Six antimicrobial agents were administered to 48 patients (divided in 6 groups) who underwent prostatectomy. Half of the patients received the antibiotic in a single dose one hour before the operation and the rest in divided doses 24 hours before the operation. The concentration levels in serum and in prostatic tissue were measured for each of the antibiotics and for each mode of administration. The obtained ratios of prostatic tissue to serum concentrations and the relative antimicrobial activity to local pathogens of each agent indicate that the agent of choice for prostatic disease is netilmicin followed by aztreonam, cefuroxime and the ticarcillin-clavulanic acid combination.

Acute Disease↗
PubMed1989

Morphological changes following ESWL in the rat kidney.

Fifty four Wistar rats were treated with 500, 1,000 or 2,000 shock waves, using the modified DORNIER HM 3 system with the new SG40 shock wave generator. The animals were sacrificed after a period of 24 hours, 7 days or 35 days. Histological examination, scanning electron microscopy (SEM) and magnetic resonance imaging (MRI) were used to evaluate acute and long term effects after extracorporeal shock-wave lithotripsy (ESWL). Acute morphological changes such as glomerular bleeding, tubular dilatation, atrophy and partial necrosis occurred immediately after ESWL throughout the kidney. SEM revealed a tubular loss of microvilli and cilia. There was restitutio ad integrum of these diffuse lesions. The extent of the long term lesions was determined by the following mechanism: venous rupture occurred during ESWL, especially in thin arcuatae veins which are, tortuous their and run between two different tissue densities. This resulted in interstitial haematoma, demonstrable by MRI; in the long term groups, the haematomas progressed to interstitial fibrosis with segmental retraction of renal convexity. The blood supply in these areas was reduced and secondary changes such as glomerular-tubular atrophy and sclerosis followed. The degree to which long-term renal lesions resulted was determined by the extent of these changes, which were shock-wave dose dependent up to a dose of 2,000 shock waves.

Animals↗
PubMed1989

Extracorporeal shock wave lithotripsy as monotherapy of staghorn renal calculi: 3 years of experience.

From May 1985 to February 1988, 61 patients with renal staghorn calculi (41 with incomplete C4 and 20 with complete C5 lesions) underwent extracorporeal shock wave lithotripsy monotherapy. Of the patients 37 were treated without preoperative Double-J* stenting, while 24 underwent Double-J stenting before extracorporeal shock wave lithotripsy. Of the patients with incomplete staghorn calculi (C4) and a preoperative ureteral stent 85% were free of stones after 6 months in contrast to only 52.4% of those without a stent and 85.7% of those with infected C4 calculi who underwent preoperative stenting. Hospitalization decreased from 17.7 days in patients without a stent to 14.2 days after stenting, followed by the number of auxiliary procedures (nephrostomy, Zeiss loop and ureteroscopy) and postoperative complications. Complete staghorn calculi (C5) without a preoperative stent had the smallest success rate of stone elimination: only 43.7% of the patients were free of stones after 6 months with a rehospitalization rate of 62.5%. For incomplete staghorn renal calculi (C4) extracorporeal shock wave lithotripsy monotherapy with a preoperative Double-J stent is the noninvasive method that offers excellent stone elimination (85%), comparable to the results of percutaneous nephrolithotripsy (with or without complementary extracorporeal shock wave lithotripsy) and anatrophic nephrolithotomy.

Combined Modality Therapy↗
PubMed1989

Problems of duodenogastric reflux in Tc-99m Hexa MIBI planar, tomographic and bull's eye display.

Tc-99m Hexa MIBI (RP-30) is excreted through hepatobiliary pathways. Myocardial imaging with RP-30 is recommended 45-60 minutes after injection. During this waiting period duodenogastric reflux (DGR) is occasionally seen. Fundal activity due to duodenogastrix reflux presents problems in planar, tomographic, and Bull's eye display. The authors recommend in those cases to give the patient a light meal and wait 15-30 minutes more for the gastric activity to empty in the small intestine before starting myocardial imaging.

Coronary Disease↗
PubMed1989

Uptake and kinetics of Tc-99m hexakis 2-methoxy isobutyl isonitrile in benign and malignant lesions in the lungs.

Kinetics of Tc-99m MIBI uptake was studied in 19 patients with lung lesions (6 benign, 13 malignant). Two dynamic studies were acquired after the I.V. injection of 10-15mCi (370-550 MBq); the first was every second for 60 seconds, followed by a second one every minute for 30 minutes. Delayed images were acquired at two and three hours. By assigning regions of interest (ROI) over the lung lesions (TR), contralateral normal lung (NL) and the heart (Ht), time activity curves (TAC) were generated and time to peak activity was calculated as well as the ratios of TR/NL, Ht/TR and Ht/NL. The Ht/NL ratio was also assessed in five patients referred with diagnosis of ischaemic heart disease (IHD) for myocardial imaging. There was a localized increase of Tc-99m MIBI uptake in ten patients with untreated malignant tumours of the lung. No localized uptake was found in one patient with untreated poorly differentiated squamous cell carcinoma, two treated lung cancer and four patients with non-malignant lesions of the lungs. Two patients with fibrosing alveolitis showed diffuse increase lung uptake. In all positive studies peak tumour was reached within the first minute. There was no statistical difference in the ratio of Ht/NL between all groups except in patients with fibrosing alveolitis. There was no significant difference between the ratios TR/NL, Ht/TR and Ht/NL at 5-10 minutes and 25-30 minutes. The ratio of TR/NL at 25-30 minutes was 1.58 +/- 0.36 in the positive cases versus 1 +/- 0.22 in the negative ones.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Phase abnormalities in right heart studies. Demonstration of six different patterns.

Phase imaging abnormalities of the right side of the heart detected on multiple gated blood pool angiography (MUGA) have received less attention than similar abnormalities of the left ventricle. It has been found that certain different patterns of phase abnormalities of both right ventricle and right atrium are useful in the detection of six pathological conditions: right bundle branch block, ischemic right coronary artery disease, pericardial effusion, tricuspid regurgitation, pulmonary hypertension, and atrial septal defect. The authors emphasize the importance of these abnormal phase patterns during interpretation of gated cardiac studies, as they are helpful in directing the physicians attention towards the proper diagnosis.

Adult↗
PubMed1981

Intraperitoneal gentamicin in appendiceal peritonitis in children: a pharmacokinetic study.

The present study was conducted in order to document the pharmacokinetic behaviour of Gentamicin when administered intraperitoneally (I.P.) in children with appendiceal peritonitis (15 patients). This pharmacokinetic behaviour was compared to that of intramuscular (I.M.) Gentamicin (12 patients). In both groups, the dose was 2.5 mg/kg/8 hours. In the I.P. group the resulting peak levels were generally low (sub-therapeutic) whilst the peak levels in the I.M. group were, in most cases, satisfactory and similar to those reported by other investigators. In both groups there was wide inter-patient variation in levels. No correlation was found between peak levels and blood Hb., haematocrit or serum urea and creatinine, but it must be noted that in most of the patients, the values of these parameters were within the normal range for their age. It emerged from the study that if Gentamicin is to be given intra-peritoneally, the dosage should be higher than that recommended for the intramuscular or intravenous route and that levels should be monitored because of interpatient variation in response.

Acute Disease↗