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Biomedical subjects

A Joubert

Publications and source records attributed to A Joubert.

12 recordsLinked to original sources
PubMed2004

Synchrotron radiation-based experimental determination of the optimal energy for cell radiotoxicity enhancement following photoelectric effect on stable iodinated compounds.

This study was designed to experimentally evaluate the optimal X-ray energy for increasing the radiation energy absorbed in tumours loaded with iodinated compounds, using the photoelectric effect. SQ20B human cells were irradiated with synchrotron monochromatic beam tuned at 32.8, 33.5, 50 and 70 keV. Two cell treatments were compared to the control: cells suspended in 10 mg ml(-1) of iodine radiological contrast agent or cells pre-exposed with 10 microM of iodo-desoxyuridine (IUdR) for 48 h. Our radiobiological end point was clonogenic cell survival. Cells irradiated with both iodine compounds exhibited a radiation sensitisation enhancement. Moreover, it was energy dependent, with a maximum at 50 keV. At this energy, the sensitisation calculated at 10% survival was equal to 2.03 for cells suspended in iodinated contrast agent and 2.60 for IUdR. Cells pretreated with IUdR had higher sensitisation factors over the energy range than for those suspended in iodine contrast agent. Also, their survival curves presented no shoulder, suggesting complex lethal damages from Auger electrons. Our results confirm the existence of the 50 keV energy optimum for a binary therapeutic irradiation based on the presence of stable iodine in tumours and an external irradiation. Monochromatic synchrotron radiotherapy concept is hence proposed for increasing the differential effect between healthy and cancerous tissue irradiation.

Carcinoma, Squamous Cell↗
PubMed2004

Evaluation of clinical teaching and professional development in a problem- and community-based nursing module.

In South Africa the main focus is on primary health care. This affects the education and training of nurses, and training schools must respond by developing appropriate teaching modules. A school of nursing developed, implemented and revised a problem- and community-based learning module over a period of three years (1996-1998). This student-centered module focuses on students' needs, active participation, collaboration, accountability, self-assessment, self-study, life-long learning and appropriate skills. In the formal clinical teaching environment PBL was the main approach. However, this approach was also supported by a variety of strategies, for example group discussions and scenarios. The knowledge, attitudes and professional development skills acquired in the PBL approach were then applied informally in the community setting (CBE). The purpose of the study was to evaluate a first year clinical teaching module as part of an extensive programme. A quantitative research method, a descriptive design, and a variety of data collection techniques were used. Conclusions were that clinical teaching was effective within the problem- (PBL) and community-based (CBE) approaches; 78% of respondents were positive about the clinical learning environment; 61% stated that expectations were met; 81% preferred group activities, and 67% indicated that they had developed professional skills. Facilitators agreed that clinical teaching met the requirements of PBL & CBE. The pass rate also improved.

Attitude of Health Personnel↗
PubMed2002

Lack of cell death enhancement after irradiation with monochromatic synchrotron X rays at the K-shell edge of platinum incorporated in living SQ20B human cells as cis-diamminedichloroplatinum (II).

In this paper we describe the results of experiments using synchrotron radiation to trigger the Auger effect in living human cancer cells treated with a widely used chemotherapy drug: cis-diamminedichloroplatinum (II) (cisplatin). The experiments were carried out at the ID17 beamline of the European Synchrotron Radiation Facility, which produces a high-fluence monochromatic beam that is adjustable from 20 to 80 keV. Cisplatin was chosen as the carrier of platinum atoms in the cells because of its alkylating-like activity and the irradiation was done with monochromatic beams above and below the platinum K-shell edge (78.39 keV). Cell survival curves were comparable with those obtained for the same cells under conventional irradiation conditions. At a low dose of cisplatin (0.1 microM, 48 h), no difference was seen in survival when the cells were irradiated above and below the K-shell edge of platinum. Higher cisplatin concentrations were investigated to enhance the cellular platinum content. The results with 1 microM cisplatin for 12 h showed no difference when the cells were irradiated with beams above or below the platinum K-shell edge with the exception of the higher cell death resulting from drug toxicity. The intracellular content of platinum was significant, as measured macroscopically by inductively coupled plasma mass spectrometry. Its subcellular localization and particularly its presence in the cell nucleus were verified by microscopic synchrotron X-ray fluorescence. This was the first known attempt at K-shell edge photon activation of stable platinum in living cells with a platinum complex used for chemotherapy. Its evident toxicity in these cells leads us to put forth the hypothesis that cisplatin toxicity can mask the enhancement of cell death induced by the irradiation above the K-shell edge. However, K-shell edge photon activation of stable elements provides a powerful technique for the understanding of the biological effects of Auger processes. Further avenues of development are discussed.

Calibration↗
PubMed2002

[Retrospective study of hospitalizations for heart failure in elderly patients in a cardiology service of a general hospital center].

The results of a retrospective study of patients over 70 years of age admitted to the cardiology department of Meaux Hospital for cardiac failure in 1997 are reported. The cases of 143 patients were analysed with respect to two age groups: 70-79 years, and over 80 years of age. The principal aetiology of cardiac failure in all ages was ischaemic heart disease. Hypertensive heart disease was observed in younger patients and valvular heart disease in the more elderly. No significant gender differences were observed in those affected by this pathology or by left ventricular systolic or diastolic dysfunction between the younger and older patients, men having more systolic dysfunction than women. The main causal factor of decompensation in all ages was supraventricular arrhythmias. From the therapeutic point of view, the prescription of ACE inhibitors was relatively common but at low doses. Re-hospitalisation for cardiac failure was common and observed mainly in patients with low ejection fractions. The average hospital stay was 12.58 days. The hospital mortality was high: 15%. Two year survival was 41% with no difference between patients with systolic or diastolic dysfunction. Pluridisciplinary management should reduce the number of re-hospitalisation, improve the quality of life and, perhaps, improve survival.

Age Factors↗
PubMed1999

The effect of the menstrual cycle on the pharmacokinetics of caffeine in normal, healthy eumenorrheic females.

OBJECTIVE: Hormonal fluctuations of estrogen and progesterone in eumenorrheic women may be capable of altering the pharmacokinetics of certain agents. The objective of this study was to determine the effect of the luteal, ovulatory and follicular phases of the menstrual cycle on the pharmacokinetics of caffeine, a low clearance, flow-independent drug. METHODS: Subjects were ten healthy, non-smoking, eumenorrheic females who were not pregnant and had not used oral contraceptives for a minimum of 3 months prior to the study. Blood samples were collected during one menstrual cycle for the determination of estradiol and progesterone concentrations during the follicular (days 2-6 post-onset of menses), ovulatory (days 13-16 post-onset of menses) and luteal (days 22-26 post-onset of menses) phases. Caffeine was administered over a single menstrual cycle during the follicular, ovulatory and luteal phases. Each subject was administered a single oral dose of caffeine (300 mg) in 100 ml of lemonade during each phase of the menstrual cycle. A venous catheter was used to collect blood samples at pre-dose and at the following time points: 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 10, 12 and 24 h. Plasma caffeine concentrations were determined using a validated ultraviolet high-performance liquid chromatography method. RESULTS: There were no significant (P < 0.05) differences in the pharmacokinetic parameters of caffeine across the menstrual cycle phases. The average area under the plasma concentration-time curve (AUCinf) was 93.01 mg 1(-1) x h and the absorption rate constant (ka) was 2.88 h(-1) during the ovulatory phase, 83.0 mg 1(-1) h and 2.06 h(-1), respectively, during the luteal phase and 84.7 mg 1(-1) x h and 1.84 h(-1), respectively, during the follicular phase. CONCLUSIONS: These findings suggest that the menstrual cycle does not significantly alter the pharmacokinetics of caffeine.

Adult↗
PubMed1996

Synthesis, biodistribution, and estrogen receptor scintigraphy of indium-111-diethylenetriaminepentaacetic acid-tamoxifen analogue.

This study was aimed at developing a hydrophilic diethylenetriaminepentaacetic acid-tamoxifen (DTPA-Tam) analogue for use in imaging estrogen receptor positive (ER+) lesions. In rat uterine cytosol, the IC50 of DTPA-Tam conjugate was 1 microM and of tamoxifen, 2 microM. Biodistribution, autoradiography, and radionuclide imaging of 111In-DTPA-Tam in breast-tumor-bearing rats showed that tumor-to-tissue ratios increased steadily between 30 min and 48 h. The in vivo response of MCF-7 breast cancer xenografts to tamoxifen and DTPA-Tam in nude mice demonstrated that DTPA-Tam could reduce tumor growth rate. These results indicate that DTPA-Tam, a new hydrophilic ER+ ligand, might be useful in diagnosing ER+ lesions.

Animals↗
PubMed1996

A formative model for student nurse development and evaluation--Part 1--Developing the model.

Preparing student nurses for the profession is a complex task for nurse educators; especially when dealing with the development of personal and interpersonal skills, qualities and values held in high esteem by the nursing profession and the community they serve. These researchers developed a model for formative evaluation of students by using the principles of inductive and deductive reasoning. This model was implemented in clinical practice situations and evaluated for its usefulness. It seems that the model enhanced the standards of nursing care because it had a positive effect on the behavior of students and they were better motivated; the model also improved interpersonal relationships and communication between practising nurses and students. The fact that students repeatedly use the model as a norm for self evaluation ensures that they are constantly reminded of the standards required of a professional nurse.

Clinical Competence↗
PubMed1996

Bioavailability of two selegiline hydrochloride tablet products.

The bioavailability of two selegiline HCl (CAS 14611-52-0) tablet products was compared in a single-blind, single-dose, randomised, two-way, cross-over study with 25 healthy volunteers. A test preparation of selegiline HCl (4 x 5 mg tablets) was compared to a reference preparation of selegiline HCl (4 x 5 mg tablets). The volunteers were randomised receiving each treatment once. Two clinic days were separated by a wash-out period of between 6 and 14 days. The variable AUC(0-infinity) was the primary characteristic of the extent of formation (bioavailability) of the selegiline metabolites, desmethylselegiline and methamphetamine. For desmethylselegiline the point estimate (90% confidence interval) of the "test/reference" mean ratio for the variable Cmax is 98.4% (91.2% to 106%), for AUC(0-infinity) 103% (97.6% to 109%), and for Cmax/ AUC(0-infinity) 95.6% (89.4% to 102%). For methamphetamine the point estimate (90% confidence interval) of the "test/reference" mean ratio for the variable Cmax is 101% (96.8% to 105%), for AUC(0-infinity) 102% (95.3% to 109%), and for Cmax/AUC(0-infinity) 99.0% (91.5% to 107%). The results of this study indicate that the test preparation is bioequivalent to the reference preparation with respect to both the rate and extent of formation of desmethylselegiline and methamphetamine.

Adolescent↗
PubMed1995

[Distance education retraining program: general nursing].

Distance- or distance contact education provides registered nurses with an ideal opportunity for professional growth. This method also fulfils a need to study without the problem of being absent from family, occupational and social responsibilities. It seemed that students are enthusiastic about their studies despite personal, financial and other difficulties. At the end of the course students claimed that their self-confidence improved and that they were better equipped to give high quality nursing care. Using the Spearman Correlation Coefficient there was substantial correlation between the metric results and the final course symbol for this group of students [alpha .05 (p.002)]. No correlation existed between the selection average of 1-9 and the different subjects as for example General Nursing and Ethos. If the decision is taken to present courses according to the distance contact education method, careful planning is essential. Some of the recommendations to assure the success include: * sound structuring of infrastructure and subject material * improvement of selecting procedures; and * the orientation of lectures to cope with the role of facilitator. The professional growth of students during their period of study proves to be worth the effort to present such a course.

Adult↗
PubMed1991

[Respiratory risk of general surgery in adults].

Disorders of ventilation and postoperative bronchial and pulmonary infections still create serious problems in general surgery. Three factors determine these complications: (1) the transient and usually resolutive repercussions of anaesthesia on ventilation; (2) the sometimes deep and prolonged alteration of lung function directly due to the surgical procedure, and (3) the patient's underlying condition. In practice, this last group of surgical patients can be divided into fragile subjects (elderly people, pregnant women), subjects at risk (smokers, malnourished or obese patients) and disabled subjects suffering from chronic obstructive or restrictive lung disease, asthma or heart disease. Preoperative clinical, radiological and, chiefly, functional evaluation leads to preventive measures. Preparation for surgery relies, to a great extent, on respiratory physiotherapy which, if needed, may be integrated in a pneumological therapeutic program. Combined with an efficient postoperative analgesia and with an optional anaesthesia technique, respiratory physiotherapy is essential to the prevention of respiratory complications in surgery.

Adult↗