LAFARA: a new underground laboratory in the French Pyrénées for ultra low-level gamma-ray spectrometry

We describe a new underground laboratory, namely LAFARA (for "LAboratoire de mesure des FAibles RAdioactivités"), that was recently created in the French Pyrénées. This laboratory is primarily designed to analyze environmental samples that display low radioactivity levels using gamma-ray spectrometry. Two high-purity germanium detectors were placed under 85 m of rock (ca. 215 m water equivalent) in the tunnel of Ferrières (Ariège, France). The background is thus reduced by a factor of ∼20 in comparison to above-ground laboratories. Both detectors are fully equipped so that the samples can be analyzed in an automatic mode without requiring permanent presence of a technician in the laboratory. Auto-samplers (twenty positions) and systems to fill liquid nitrogen automatically provide one month of autonomy to the spectrometers. The LAFARA facility allows us to develop new applications in the field of environmental sciences based on the use of natural radionuclides present at low levels in the environment. As an illustration, we present two of these applications: i) dating of marine sediments using the decay of (226)Ra in sedimentary barite (BaSO(4)), ii) determination of (227)Ac ((231)Pa) activities in marine sediment cores.

Gamma-ray emission concurrent with the nova in the symbiotic binary V407 Cygni

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.

Use of heliox in patients with severe exacerbation of chronic obstructive pulmonary disease

OBJECTIVE

To assess whether patients with chronic obstructive pulmonary disease treated with heliox have a better prognosis than those treated with standard therapy.

DESIGN

Retrospective analysis over 18 months.

SETTING

Academic emergency department.

PATIENTS

Eighty-one patients admitted with exacerbation of chronic obstructive pulmonary disease and respiratory acidosis.

INTERVENTIONS

Use of helium-oxygen mixture as an adjunctive therapy.

MEASUREMENTS AND MAIN RESULTS

The following data were collected: age, gender, medical history, vital signs, arterial blood gas at admission, emergency room treatment, requirement for intubation, admission in intensive care unit, length of stay, and evolution. Patients were classified into two groups according to whether heliox was used as a therapeutic agent (heliox group) or not (standard group). Chi-square test and Student's t-test were used for statistical analysis (significant at p <.05). In both groups, the following data were similar: age, gender, medical history, vital signs, initial arterial blood gas, and emergency room treatment. Significant decreases in intubation, and mortality rate were identified in the heliox group. Significant decreases in intensive care unit stay and in-hospital stay were observed for survivors in the heliox group.

CONCLUSION

Use of heliox seems to improve prognosis in patients with severe acute exacerbation of chronic obstructive pulmonary disease. Prospective randomized studies are needed to confirm these results.

Medical student effect on emergency department length of stay

STUDY OBJECTIVE

Taking advantage of a medical student strike, the authors evaluated the effect of medical students on emergency department length of stay (LOS).

METHODS

ED LOS and patient characteristics were compared for the 4-day strike period and the same days the week before. Proportions were compared by using the Mann-Whitney U test and the chi(2) test (P <.05).

RESULTS

Eight hundred thirty-one patients were studied. There was no significant difference between the study and control periods for the general patient characteristics or laboratory or radiologic investigations. Median LOS decreased by 24% (31 minutes, 95% confidence interval [CI] 24 to 38) during the strike (110 minutes [95% CI 65 to 178] to 79 minutes [95% CI 40 to 135], P <10(-4)).

CONCLUSION

Medical students lengthen ED LOS. This should be explained to patients and should be considered as one justification for increasing medical staff in the teaching ED.

Medical faculty as humanistic physicians and teachers: the perceptions of students at innovative and traditional medical schools

BACKGROUND AND OBJECTIVES

The training of caring physicians represents an important goal of medical education. Little is known however, on whether medical faculty constitute good role models for teaching humanistic skills to medical students. In this study, we examined to what extent medical students at innovative and traditional schools perceived their teachers as humanistic physicians and teachers. We also explored whether pre-clinical and clinical students shared the same perceptions.

METHODS

A mail survey was conducted in Canada of all second-year students and senior clerks at one innovative medical school (problem-based learning (PBL), patient-centred, community-oriented) and three traditional medical schools. Students were asked to what extent they agreed or disagreed that the majority of their teachers behaved as humanistic physicians and teachers; 10 statements were used. Overall, 65% of the 1039 students returned the questionnaire.

RESULTS

Over 25% of second-year students and 40% of senior clerks did not agree that their teachers behaved as humanistic caregivers with patients or were good role models in teaching the doctor-patient relationship. More than half of second-year students and senior clerks did not agree that their teachers valued human contact with them or were supportive of students who had difficulties. There were few differences in the way medical students at innovative and traditional schools perceived their teachers' humanistic qualities. At the pre-clinical level however, there were more students from the innovative school than from the traditional schools (around 60% vs. 40%, P < 0.005) who agreed that their teachers valued human contact with them and were supportive of students.

CONCLUSION

Our results indicate that the PBL curriculum fosters better teacher-student relationships during the pre-clinical years. They also suggest that an unacceptably large number of medical students are taught by physicians who seem to lack compassion and caring in their interactions with patients. This study questions the adequacy of medical faculty as role models for the acquisition of caring competence by medical students.

[The effect of "seniorization" on the prescription of biological tests in an admissions and emergency service]

This prospective study compared the prescriptions of biological tests (PBT) for patients admitted to an Emergency medical service (EMS) of a University hospital, according as to whether the staff consisted either of medical residents only (study period P1) or of residents trained in emergency medicine and continuously supervised by a senior specialist (study period P2). During the one-month study periods, a total of 5,948 patients were admitted (2,781 during P1 and 3,167 during P2 respectively). Between P1 and P2 the rate of PBT decreased by 38.8% (P < 0.0001), the mean expenses for PBT per patient by 13.8% (P < 0.0001) and the total expenses by 53.4%. Teaching and training of residents in emergency medicine and supervision by a senior specialist improve the quality of care and decrease health care cost.

Recruitment of primitive peripheral blood cells: synergism of interleukin 12 with interleukin 6 and stromal cell-derived FACTOR-1

In bone marrow, haematopoietic stem cells (HSC) rely on close contact with stromal cells for proliferation and differentiation. Stromal cell-derived factor (SDF-1) is a chemokine produced by bone marrow stromal cells and has been reported to be a chemoattractant for CD34(+)cells. SDF-1 was evaluated for effects on proliferation of both mature and immature human progenitor cells in vitro. Neither proliferation nor maturation of peripheral blood cells was stimulated by SDF-1 alone. Moreover, we have previously demonstrated that 5-fluorouracile (5-FU) resistant HSC require a combination of interleukin 12 (IL-12), IL-6 and SCF for the production of morphologically recognizable clonogenic elements at day 14 in semisolid medium. Our data reported a strong enhancement of the IL-6, IL-12, SCF-induced synergism (172%) by SDF-1 (296.5%). Furthermore, our data suggest that this chemokine alone had no effect on triggering quiescent cells and may preserve these cells from 5-FU cell damage or upregulate early-acting cytokine receptors. Thus, SDF-1 might play a key role in early human haematopoiesis through its potent synergistic effects in combination with early-acting cytokines. These results suggest that a programmed response to sequential cytokine stimulation may be part of a control mechanism required for maintenance of proliferation of primitive HSC.

PA26, a novel target of the p53 tumor suppressor and member of the GADD family of DNA damage and growth arrest inducible genes

Exposure of mammalian cells to hypoxia, radiation and certain chemotherapeutic agents promotes cell cycle arrest and/or apoptosis. Activation of p53 responsive genes is believed to play an important role in mediating such responses. In this study we identified a novel gene, PA26, which maps to chromosome 6q21 and encodes at least three transcript isoforms, of which two are differentially induced by genotoxic stress (UV, gamma-irradiation and cytotoxic drugs) in a p53-dependent manner. A functional p53-responsive element was identified in the second intron of the PA26 gene, in consistance with a mechanism of transcriptional induction of the PA26 gene by p53. No clues to its functions were revealed by sequence analysis, although pronounced negative regulation by serum factors argues for a potential role of PA26 in growth regulation. Immunological analysis suggests that PA26 protein(s) is localized to the cell nucleus. Our results suggest that the PA26 gene is a novel p53 target gene with properties common to the GADD family of growth arrest and DNA damage-inducible stress-response genes, and, thus, a potential novel regulator of cellular growth.

Clinical teachers as humanistic caregivers and educators: perceptions of senior clerks and second-year residents

BACKGROUND

The acquisition and nurturing of humanistic skills and attitudes constitute an important aim of medical education. In order to assess how conducive the physician-learning environment is to the acquisition of these skills, the authors determined the extent to which clinical teachers are perceived by their trainees as humanistic with patients and students, and they explored whether undergraduate and graduate students share the same perceptions.

METHODS

A mail survey was conducted in 1994/95 of all senior clerks and second-year residents at Laval University, University of Montreal and University of Sherbrooke medical schools. Of 774 trainees, 259 senior clerks and 238 second-year residents returned the questionnaire, for an overall response rate of 64%. Students' perceptions of their teachers were measured on a 6-point Likert scale applied to statements about teachers' attitudes toward the patient (5 items) and toward the student (5 items).

RESULTS

On average, only 46% of the senior clerks agreed that their teachers displayed the humanistic characteristics of interest. They were especially critical of their teachers' apparent lack of sensitivity, with as many as 3 out of 4 declaring that their teachers seemed to be unconcerned about how patients adapt psychologically to their illnesses (75% of clerks) and that their teachers did not try to understand students' difficulties (78%) or to support students who have difficulties (77%). Compared with the clerks, the second-year residents were significantly less critical, those with negative perceptions varying from 27% to 58%, 40% on average. Except for this difference, their pattern of responses from one item to another was similar.

INTERPRETATION

This study suggests the existence of a substantial gap between what medical trainees are expected to learn and what they actually experience over the course of their training. Because such a gap could represent a significant barrier to the acquisition of important skills, more and urgent research is needed to understand better the factors influencing students' perceptions.

Diagnosis of nosocomial pneumonia in mechanically ventilated patients: repeatability of the bronchoalveolar lavage

The repeatability of the bronchoalveolar lavage (BAL) was assessed prospectively in 44 mechanically ventilated patients with suspected nosocomial pneumonia. Two BAL were performed in the same lung area (contiguous segment) during two fibroscopic procedures performed with a thirty minute interval. All the bronchoscopies were performed by the same operator. The statistical analysis looked out for bias (MacNemar test), agreement, and repeatability (kappa test). In the 44 patients studied, the qualitative repeatability (i.e., presence or absence of bacteria) was excellent (95.4%). However, in the 16 patients having at least one positive culture, these results were more controversial. The quantitative repeatability for bacteria (same log10 for both BAL of the same patient) was the lowest of all the results (26.7%). The distinction between presence and absence of bacterial pneumonia (based on the 10[4] cfu/ml threshold) showed a repeatability of 75% with no bias, an agreement of 47% and a just-significant kappa test (test = 1.97; p = 1.96 for a 5% risk error). BAL seems to have excellent repeatability when sterile. Its repeatability when positive needs further studies to be assessed.

A pilot course as a model for implementing a PBL curriculum

Many medical schools are shifting to a problem-based learning (PBL) curriculum, some without any transition period, others using periods of parallel-track curricula. The authors report on and discuss a third strategy for implementing PBL: using a pilot course as a model to facilitate the transition. After the Université de Montréal Faculty of Medicine chose to switch PBL, one course in the third year of the traditional curriculum was changed to PBL format 11 months before the new curriculum was to start in September 1993. This was done to develop local expertise, to gain confidence, to test the feasibility of the method, to produce a showcase, to assess more accurately the resources required, and to provide a practice ground for the curriculum planners and managers and the faculty-development training team. The authors discuss the planning of the pilot course, the training of the faculty in various aspects of PBL (writing problems, tutoring methods, etc.), the course implementation, and the course evaluation. Overall, the pilot course was well received by both the faculty and the students and provided much beneficial information that assisted the university in its transition to a new PBL curriculum.

Automated multiple analysis of protein structures: application to homology modeling of cytochromes P450

A computational strategy for homology modeling, using several protein structures comparison, is described. This strategy implies a formalized definition of structural blocks common to several protein structures, a new program to compare these structures simultaneously, and the use of consensus matrices to improve sequence alignment between the structurally known and target proteins. Applying this method to cytochromes P450 led to the definition of 15 substructures common to P450cam, P450BM3, and P450terp, and to proposing a 3D model of P450eryF.

Oxidation of tienilic acid by human yeast-expressed cytochromes P-450 2C8, 2C9, 2C18 and 2C19. Evidence that this drug is a mechanism-based inhibitor specific for cytochrome P-450 2C9

Oxidation of tienilic acid by human cytochromes P-450 (CYP) 2C9, 2C18, 2C8 and 2C19 was studied using recombinant enzymes expressed in yeast. CYP 2C9 was the best catalyst for 5-hydroxylation of tienilic acid (K(m) = 5 +/- 1 microM, kcat = 1.7 +/- 0.2 min-1), 30-fold more potent in terms of kcat/K(m) than CYP 2C18 (K(m) = 150 +/- 15 microM, kcat = 1.8 +/- 0.2 min-1) and 300-fold more potent than CYP 2C8 (K(m) = 145 +/- 15 microM, kcat = 0.2 +/- 0.1 min-1). CYP 2C19 was unable to catalyze this hydroxylation under our experimental conditions. During this study, a marked effect of the ionic strength on the activities (hydroxylations of tienilic acid and tolbutamide) of these cytochromes P-450 expressed in the yeast strain 334 was observed. The effect was particularly great in the case of CYP 2C18, with a tenfold decrease of activity upon increasing ionic strength from 0.02 to 0.1. Specific-covalent binding of tienilic acid metabolites to cytochrome P-450 (incubations in the presence of 5 mM glutathione) was markedly higher upon tienilic acid oxidation by CYP 2C9 than by CYP 2C18 and CYP 2C8. Mechanism-based inactivation of cytochrome P-450 during tienilic acid oxidation was observed in the case of CYP 2C9 but was not detectable with CYP 2C18 and CYP 2C8. Tienilic acid thus appears to be a mechanism-based inhibitor specific for CYP 2C9 in human liver. Experiments performed with human liver microsomes confirmed that tienilic acid 5-hydroxylase underwent a time-dependent inactivation (apparent t1/2 = 10 +/- 5 min) during 5-hydroxylation of tienilic acid.

[Buprenorphine abuse in a series of 50 drug addicts hospitalized at a Drug Dependence Evaluation hospital in Marseille]

Buprenorphine, a synthetic central analgesic, marketed since 1987, was rapidly suspected to be subject to abuse. We tried to confirm this abuse in the context of our analytical activity at the Drug Dependence Evaluation and Information Centre. The study was based on 50 drug addicts admitted to Marseille Hospital between June and October 1992. Buprenorphine and its N-dealkylated metabolite were identified in the urine by high performance liquid chromatography equipped with a diode array detector. Nine (18%) of the 50 samples analysed were positive for buprenorphine and/or norbuprenorphine, with a confidence interval of 8 to 28%, which confirms the existence of abuse of this analgesic.

Putaminal necrosis after methanol intoxication

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Immunological evaluation of harvested stem cells obtained by leukapheresis after chemotherapy

Some patients suffering from malignancies may benefit of myeloablative chemotherapy followed by hematological reconstitution with autologous peripheral blood reinfusion. A quick evaluation of the number of hematopoietic progenitors present in leukapheresis blood samples is necessary to ensure the collection of a sufficient number of these cells. A study was performed on a series of 25 leukapheresis following initial chemotherapy. The number of granulomonocytic colony-forming unit (CFU-GM) and the number of CD34+ cells were evaluated simultaneously, in each sample. Results have shown a relatively strong linear correlation between both methods of evaluation of hematopoietic progenitors, suggesting that immunophenotyping could be a useful method to estimate the number of progenitors.

Basic Training Program in Medical Pedagogy: a 1-year program for medical faculty

In 1979 université de Montréal developed the Basic Training Program in Medical Pedagogy; the program has since been offered at two other Canadian medical schools. The learning activities are spread over an academic year so that the teachers are able to continue their clinical or research duties. The program, which follows a model of systematic instruction, comprises 17 self-instructional modules on basic educational topics adapted to medical teaching. The topics are related to four components of an integrated system: student needs and learning objectives, instructional methods, student evaluation and program evaluation. The instructional format is aimed at three levels--understanding, analysis and application--to which assignments and assessments are related. In addition to the modules, the program offers 15 half-day sessions for small groups (five participants and one instructor) to discuss aspects of the program, especially home assignments and the application of personal educational projects. A minimum of 100 hours of personal time is requested. The program's main goal is that students be placed at the centre of the educational process. Of 215 participants since 1979, 171 (80%) have completed the program and reported high satisfaction. Issues related to any faculty development program are discussed.

[Psychic effects of drugs prescribed for hypertensive patients. An experiment of the Regional Drug Monitoring Center in Marseilles]

The authors present typical observations of behavioural adverse effects induced by anti-hypertensive drugs and reported to the Marseilles Regional Center of Pharmacovigilance. These effects include: sleep disorders, confusion, psychotic reactions and depression. Surprisingly, these effects seem to be very rarely reported; this is perhaps due to a tricky assessment of the causal relationship: many factors (hypertension, other diseases, other drugs) can have an influence on these troubles.

New evaluations of circulating granulocyte and macrophage stem cells in healthy adults using conditioned media and recombinant human growth factors

Peripheral human blood contains granulo-monocyte (CFU-GM) and eosinophil (CFU-Eo) progenitors. In vitro, the number of colony forming units is thought to range from 0.1-14 per 2 x 10(5) plated cells. We show that the number of CFU-GM, Eo depends on culture methods. By modifying the usual assay method (using human umbilical cord plasma and the association of 2 stimulating conditioned media: activated lymphocyte conditioned medium and bone marrow fibroblast conditioned medium), we found different circulating CFU-GM, Eo numbers. The mean number of circulating CFU-GM, Eo in 107 healthy adults was 22.4 per 2 x 10(5) plated cells (range: 1-84). There was a slight difference between males (mean number: 23.6) and females (mean number: 20.4). The mean number of CFU-GM, Eo harvested on Percoll gradient was 123/ml of peripheral blood (range: 7-513). These results are far over those commonly reported in literature. This suggests that these latter results were probably underestimated. The use of recombinant human interleukin 3 and recombinant human GM (granulocyte-monocyte) colony-stimulating factors shows that CFU-GM, Eo numbers are found to be comparatively increased compared to that obtained with our modified method (using rhIL-3 alone), or that the size of those colonies is notably increased (using rhIL-3 + rhGM-CSF).

[Mucous diaphragm of the cervical esophagus. Apropos of 38 cases discovered during upper endoscopy at the General Hospital of Dakar. Relationship with the Kelly-Paterson or the Plummer-Vinson syndrome]

At the occasion of 15,000 high endoscopies performed during the past 5 years at the general Hospital of Dakar (Senegal) 38 mucous diaphragms of cervical esophagus were discovered. 36 patients are Black Senegalese; 29 females and 9 males with a mean age of 37. Dysphagia was present 29 times and anemia 22 times. Endoscopies diagnosis is easy, putting into light a mucous diaphragm at the level or immediately below Killian mouth. 18 of these cases have been classified as Kelly-Paterson syndrome. Performed in 30 patients, the treatment consists in breaking down the mucous diaphragm with an endoscope. It is difficult to keep on endoscopic monitoring, although it is essential because the risk of cancerisation.

[The value of laparoscopy. Results of 600 studies performed in an internal medicine department at the General Hospital of Dakar]

600 laparoscopic examinations were performed in an Internal Medicine Department of the general Hospital Dakar (Senegal) from 1984 to 1989 in 402 males and 198 females aged from 7 to 82 years. This examination of simple and quick procedure well tolerated under simple premedication, should be performed only after diffusion of the pneumoperitoneum, per- foration being the major risk. Even if liver cell carcinoma and cirrhosis represent more than an half of the examined cases (52%) due to their high frequency, exploration of peritoneal pathology is the best indication for laparoscopy. Thanks to laparoscopy, 68 tuberculosis, 28 peritoneal carcinomatosis and 11 infectious peri-hepatitis were diagnosed. It remains a major examination perfectly adapted to studies of the so-frequent hepato-peritoneal pathology in Black Africa]

Peripheral blood stem cells collected before and after leukapheresis in the very early remission phase of hematopoietic malignancies

Human peripheral blood obtained after chemotherapy-induced remission in hemopoietic malignancies has been suggested to be a potential substitute for autologous bone marrow as regards autologous hematopoietic reconstitution. The schedule and consequences of early leukapheresis are, however, still imprecise. We report a study performed in two series of, respectively, 10 and 14 patients where sequential leukapheresis (total number = 84) was evaluated with regard to colony-forming unit (CFU) potency. Our data demonstrate that adequate numbers of progenitor cells can be collected by leukapheresis and that, even when this is performed at an early stage after remission, subsequent hematopoietic reconstitution is not impaired.

[Human immunodeficiency virus infections (HIV-1 and HIV-2) in Dakar. Epidemiologic and clinical aspects]

The authors report on the results of an investigation carried out on 109 HIV seropositives ascertained by the Dakar Central Hospital between February 20, 1987 and May 31, 1988. These seropositives affected 44 patients with AIDS (0.78% of admitted patients) and 65 seropositive people of which 43 blood donors (1.35% of donors). Both viruses are present in about equal number: 50 HIV1 seropositives, 44 HIV2 seropositives, and 15 composite seropositives. Sex-ratio is 3,9 in favour of males; this figure is nearer to the one observed in Europe and North American than the one observed in Central Africa where there is equality between both sex. Clinical patterns are dominated by a bad general status: lost of weight, fever, diarrhea, polyadenopathiae, pneumopathiae, meningoencephalitis. Kaposi's sarcoma and cryptococcal meningitis have been observed only four times. Development of the infection lead to death for 12 patients during the 16 months of the investigation. Both viruses are responsible for an equal immunodepression, leading to the same potential severity. Immunodepression might be acquired more slowly with HIV2, so strongly suggesting an incubation apparently lasting more.

Combined myeloid cell synchronization and chromosome G-banding by bromodeoxyuridine

A combined high-resolution G-banding technique and cell synchronization of bone marrow cultures by BrdU is presented and compared with direct technique, standard 24-hour culture, and synchronization both with low temperature and methotrexate. Mitotic count and quality of spreading are improved in comparison with unsynchronized techniques. Precision of banding is increased significantly compared with the four other techniques used. Our procedure, which presents the advantage of combined synchronization and banding, is simple, time-saving, and provides more information about the chromosomes. Our results suggest that the GB-FPG technique should be a method of choice for the synchronization of bone marrow cells.

[Failure of gastric lavage in severe drug poisoning. Value of esophagogastric fibroscopy]

A case is reported of massive drug self-poisoning (more than 200 pills associated with slices of oranges) in which repeated gastric lavage failed to empty the stomach. An attempt to split up the amalgamated pills, adherent to the gastric mucosa, by fibre-optic gastroscopy failed and a gastrotomy was required. Endoscopy together with gastric lavage is indicated in certain situations to quickly empty the stomach and so shorten the course of the poisoning. Indications are the large number of pills swallowed, a poor result of the treatment, a worsening of the clinical condition despite treatment, and three positive gastric toxicological assays within the first 24 h.