PubMed Health⌕ Search

Biomedical subjects

A Ionescu

Publications and source records attributed to A Ionescu.

At least 19 recordsLinked to original sources
PubMed2006

Modeling of soiling based on silica-soda-lime glass exposure at six European sites.

Samples of silica-soda-lime float glass, a material selected as a pertinent soiling sensor, were exposed for up to 28 months at four urban sites (Athens, Krakow, London and Prague) and at a semi-urban one (Monte Libretti, near Rome), sheltered from rain. This exhaustive experience permitted to complete and to test the generalisation ability of the results previously obtained on the same material, exposed according to the same protocol, during 24 months, at a single site (Paris). The model previously fitted for the Paris experiment, the Hill equation, could be successfully generalised for four other sites of exposure (Athens, Krakow, Prague and Rome). The analytical form of this model was interpreted in terms of a physical description of the soiling phenomenon. Some of the model coefficients were different from one site to another, depending on the specific environment of exposure (air pollution levels, meteorological factors), while the other ones were rather equivalent. The analysis of the model coefficients, on the one hand, led to an estimation of the period after which soiling is close to its saturation level, and on the other hand, it will permit to correlate these coefficients to the environmental factors, in order to select the most appropriate ones for building dose-response functions for soiling, with broad geographical application.

Journal Article↗
PubMed2004

Ganglion cells from chick retina display multiple functional nAChR subtypes.

We have examined the properties of nicotinic acetylcholine receptors in embryonic chick retinal ganglion cells. Ganglion cells, identified according to morphological and physiological criteria, displayed spontaneous or induced action potentials. In 94/99 cells acetylcholine pulses evoked responses. In current clamp mode, acetylcholine provoked membrane depolarization and triggered action potentials. Under voltage clamp conditions, acetylcholine evoked inward currents that were readily blocked by d-tubocurarine. Antagonists specific for homomeric (alpha-bungarotoxin) and heteromeric (dihydro-beta-erythroidine) receptors revealed that ganglion cells express multiple functional receptor subtypes. These findings demonstrate that ACh modulates the electrical activity of these cells and is likely to mediate synaptic transmission. The presence of multiple receptor subtypes may contribute to processing and transmission of information in the retina.

Acetylcholine↗
PubMed2003

Prevalence and clinical significance of incidental paraprosthetic valvar regurgitation: a prospective study using transoesophageal echocardiography.

OBJECTIVE: To assess the prevalence, mechanisms, and significance of paraprosthetic regurgitation detected incidentally by transoesophageal echocardiography (TOE) in patients after heart valve replacement. DESIGN: Prospective observational study. SETTING: Tertiary referral centre. PATIENTS: 360 consecutive patients (mean (SD) age 65.8(9.5) years, 193 women) undergoing elective first ever valve replacement. METHODS: Postoperative and follow up TOE, and tests for haemolysis and anaemia. RESULTS: There were 243 aortic, 90 mitral, and 27 double valve replacements, using 316 mechanical and 44 tissue valves, giving 270 aortic and 117 mitral valves. One patient with severe paraprosthetic mitral regurgitation underwent immediate reoperation and was excluded from subsequent analyses. Paraprosthetic jets were detected around 16 (6%) of the aortic and 38 (32%) of the mitral valves (p < 0.05) at the postoperative study. Follow up TOE was available for 151 aortic and 67 mitral valves, 0.9 (0.5) years after operation. Paraprosthetic jets were present in 15 (10%) of the aortic and 10 (15%) of the mitral valves (NS). Two thirds of the aortic and a fifth of the mitral jets were new. Paraprosthetic jets were more common in aortic valves in a supra-annular (12 of 88, 14%) than in an intra-annular position (4 or 182, 2%; p < 0.005) and in mitral valves inserted with continuous (36 of 88, 41%) rather than interrupted sutures (2 of 28, 7%; p < 0.001). Lactate dehydrogenase concentration was higher in patients with paraprosthetic jets than in those without (752 (236) v 654 (208) IU/l, p < 0.001). Haemoglobin and haptoglobin concentrations were not different. CONCLUSIONS: Small paraprosthetic leaks are common, are related to surgical factors, are not associated with increased subclinical haemolysis, and are benign during the first year after heart valve replacement.

Aged↗
PubMed2003

Incidence of embolism and paravalvar leak after St Jude Silzone valve implantation: experience from the Cardiff Embolic Risk Factor Study.

BACKGROUND: Silver coating of the sewing ring (Silzone) was introduced as a modification of the St Jude Medical standard valve to provide antibacterial protection, but the valve has recently been withdrawn. OBJECTIVE: To study patients with these prostheses to assess possible adverse effects, and to guide their follow up. DESIGN: Prospective observational study of risk factors for stroke after valve replacement. SETTING: Cardiology and cardiac surgery departments in a tertiary centre. PATIENTS: There were 51 patients with Silzone and 116 with St Jude Medical standard valves. Patients undergoing aortic valve replacement were well matched for stroke risk factors. Silzone patients with mitral valve replacement were younger (mean (SD) age 61 (10) v 66 (7) years), more likely to be female (95% v 65%), and had more pulmonary arterial hypertension (100% v 78%), but fewer coronary artery bypass grafts (5% v 33%) than patients with standard mitral valve replacements (all p < 0.05). RESULTS: Follow up was 100% in the Silzone group (mean duration 3.0 (0.9) years) and 97.4% in the standard group (4.7 (1.4) years). Survival, morbidity, and anticoagulant control were documented over 682 follow up years (153 for Silzone and 529 for standard). There were six embolic strokes and one peripheral embolism in the Silzone group, all within three months after operation, and five embolic strokes and one peripheral embolism in the standard group. Freedom from major thromboembolism at three months was 65% in the Silzone mitral valve replacement group and 100% in the standard mitral valve replacement group (difference 35%, 95% confidence interval 8% to 62%). There was one reoperation for paravalvar leak in the standard group, but none in the Silzone group (NS). Anticoagulant control in the two groups was similar. CONCLUSIONS: Patients with Silzone mitral valves had a high rate of early postoperative embolism but no excess paravalvar leak.

Adult↗
PubMed2001

Task-related chemical analysis of labial gland volatile secretion in worker honeybees (Apis mellifera ligustica).

Chemical analyses revealed that the labial gland complex of worker honeybees possesses a series of hydrocarbons dominated by odd-numbered carbon chain alkanes along with minor amounts of alkenes and branched alkanes. Foragers contained significantly more secretion than nurse bees. Experiments with bees from colonies induced to have a division of labor independent of age revealed that the differences in the amount of secretion were task, but not age dependent.

Age Factors↗
PubMed2001

Localized pericardial tamponade: difficult echocardiographic diagnosis of a rare complication after cardiac surgery.

We report 2 cases of localized pericardial tamponade occurring soon after cardiac surgery, in which the diagnosis could not be made with transthoracic echocardiography. Computed tomography and transesophageal echocardiography, respectively, were necessary, and this underlies the importance of alternative imaging modalities when this condition is suspected. A high index of suspicion is crucial for reaching the correct diagnosis.

Aged↗
PubMed2000

The diagnosis of ventilator-associated pneumonia using non-bronchoscopic, non-directed lung lavages.

OBJECTIVES: (1)To assess the diagnostic utility of quantitative cultures of non-bronchoscopic lung lavage (NBL) in ventilator-associated pneumonia and evaluate the role of the Bacterial Index; (2) To assess the predictive value of NBL surveillance quantitative cultures in ventilated patients; (3) To evaluate the Clinical Pulmonary Infection Score (CPIS) system in ventilated patients. DESIGN: A prospective comparison of NBL with bronchoscopic bronchoalveolar lavage and protected specimen brush. SETTING: Three intensive care units in academic tertiary care centres. PATIENTS: 145 adults ventilated for 72 h, with and without clinical signs of pneumonia. INTERVENTIONS: Sampling of lower airway secretions by NBL, bronchoalveolar lavage and protected specimen brush. MAIN OUTCOME MEASURES: Diagnostic reliability of quantitative cultures, Bacterial Index and CPIS. RESULTS: 34 episodes of clinical ventilator-associated pneumonia were documented in 32 patients. 9 episodes were confirmed by concordant blood/pleural culture or post-mortem lung examination. Qualitative concordance of the predominant pathogen between sequential NBL: bronchoalveolar lavage and protected specimen brush was 83 %. Sensitivity and specificity of non-directed bronchial lavage at a threshold of 10(4) CFU/ml were 68 % and 70 % respectively (p = 0. 003) and were comparable with the bronchoscopic methods. However, the low positive predictive value of NBL indicates that quantitation in the absence of clinical signs is unlikely to be useful. Bacterial Index did not improve discriminatory power of quantitation compared with bacterial load of predominant organism. Mean CPIS for confirmed pneumonia cases was 8.4 +/- 1.01, significantly higher than for non-pneumonia observations (p = < 0.0001). CONCLUSION: NBL is a simple, safe, cheap, readily-available method of diagnosing ventilator-associated pneumonia with comparable diagnostic accuracy to bronchoscopic techniques. Quantitation of respiratory tract cultures can exclude pneumonia in patients with equivocal clinical signs. The diagnostic threshold should vary depending on the length of ventilation, likelihood of pneumonia and antibiotic administration. The Bacterial Index is a flawed mathematical device that has no contributory role in pneumonia diagnosis. The CPIS has some diagnostic role in selected cohorts of ventilated patients.

APACHE↗
PubMed1997

Evaluation of a protocol to select patients of all ages for cardioversion from atrial fibrillation.

OBJECTIVE: to audit the success of a decision protocol to select patients for cardioversion from atrial fibrillation or flutter by recording the success of cardioversion and the maintenance of sinus rhythm over a 2-year period. DESIGN: retrospective case notes review. SETTING: a teaching hospital coronary care unit and cardiology department. PATIENTS: 227 consecutive patients were considered for cardioversion from atrial fibrillation or flutter from 1989 to 1992; 128 fulfilled the selection criteria. MAIN OUTCOME MEASURES: successful cardioversion and maintenance of sinus rhythm after cardioversion. RESULTS: 116 (91%) patients selected by application of the guidelines were successfully cardioverted. The probabilities of maintaining sinus rhythm at 6, 12 and 24 months were 0.92, 0.88 and 0.73 respectively. CONCLUSION: careful selection of patients in atrial fibrillation identifies a group in whom cardioversion is likely to be safe and successful regardless of age.

Adult↗
PubMed1996

Apoptosis induced by beta-N-oxalylamino-L-alanine on a motoneuron hybrid cell line.

It has been suggested that beta-N-oxalylamino-L-alanine, a non-protein amino acid present in the Lathyrus Sativus seeds, may play a role in the etiopathogenesis of neurolathyrism, a toxic form of motor neuron disease clinically characterized by a severe spastic paraparesis. In order to investigate the mechanisms of beta-N-oxalylamino-L-alanine-mediated cell death, we studied the effect of this neurotoxin as well as other excitatory amino acids agonists on the growth and survival of motoneuron hybrid ventral spinal cord 4.1 cells. beta-N-oxalylamino-L-alanine was toxic to ventral spinal cord 4.1 cells in a concentration-dependent fashion (0.5-10 mM). Among the excitatory amino acids tested, only glutamate (1-10 mM), quisqualate (1 mM) and, with less extent, beta-N-methylamino-L-alanine (10 mM) induced a significant reduction of cell survival. The effect of Lathyrus Sativus neurotoxin was a slow process, becoming apparent only after 24-48 h of incubation. Interestingly, a mathematical analysis applied to the time course and dose curve of beta-N-oxalylamino-L-alanine toxicity suggested that even for very low concentrations of the amino acid it is theoretically possible to predict a time-dependent effect. The cell death was not blocked by antagonists of N-methyl-D-aspartate or non-N-methyl-D-aspartate receptors; aurintricarboxylic acid and alpha-tocopherol gave a partial protection; cysteine (1 mM) prevented the toxic effect of both Lathyrus Sativus neurotoxin and glutamate as well as quisqualate. Morphologically, in the presence of either beta-N-oxalylamino-L-alanine, glutamate or quisqualate, ventral spinal cord 4.1 cells showed apoptotic features also confirmed by ISEL technique and agarose gel electrophoresis of genomic DNA. Thus, our results suggest that in ventral spinal cord 4.1 motoneuron hybrid cells, in the absence of functional synaptic excitatory amino acid receptors, beta-N-oxalylamino-L-alanine induces cell degeneration through an apoptotic mechanism, possibly mediated by a block of cystine/glutamate Xc antiporter.

Amino Acids, Diamino↗
PubMed1988

Uterine microcurettage with combined endometrial histopathology and cytology. An alternative to conventional curettage.

A new disposable mechanical curette, the Inocurette, was used to obtain endometrial samples for histopathology and cytology. The instrument was tested on 120 patients; 37 patients were known from a previous conventional curettage (D & C) to have an endometrial cancer and 83 patients were referred to the County Hospital of Trelleborg for curettage because of dysfunctional bleedings. In all 120 patients a D & C followed the microcurettage procedure. The samples were randomized, coded and analyzed blind without any clinical information. In all but 3 patients with a known endometrial cancer, sufficient microcurettage sample material for either histopathology or cytology was obtained. In all but one of these 34 patients either a malignant diagnosis or seriously atypical cells were found. Using only cytology five out of 34 samples were designated adequate but normal. In a further 5 of the 37 patients the samples obtained at the subsequent D & C were inadequate for diagnosis; one sample was denoted as normal. In the 83 patients with dysfunctional bleedings, sufficient material for diagnosis after microcurettage, cytology and D & C was obtained in 74, 83 and 79 patients respectively. One endometrial cancer was disclosed by all three methods. Inocurette sampling causes little discomfort and requires no special training. The combined microcurettage--cytology procedure may be recommended as an alternative to conventional curettage, though, for the time being, D & C should not be replaced for cytology alone.

Curettage↗
PubMed1985

Quantitative structure-activity relationship (QSAR) applications in chemical carcinogenesis. III. QSAR analysis of some phenolic antioxidants.

Quantitative structure-activity relationships (QSAR) were formulated for a series of 22 phenolic inhibitors of carcinogenesis, taking into account: a) the inhibition of forestomach tumor induction in benzo(a)pyrene fed mice, as biological parameter and b) minimal topological differences (MTD), lipophilicities, quantum mechanic indices (epsilon LE, epsilon HO, and delta E1) and Hammett constants, as structural and physicochemical ones. Significant multilinear regression equations were found for a set of 22 compounds, two 2,6-di-tert-butyl derivatives (4 and 22) diverting from the general correlations. The obtained correlations support the conclusion that the antioxidizing potential is not directly responsible (in a rate determining step) for the inhibitory properties of the investigated phenols.

Animals↗