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Rationale and Objectives: The authors evaluated the artifacts observed on myocardial perfusion curves derived from an inversion-prepared fast gradient-echo (GRE) imaging sequence in dogs after injection of a gadolinium-based contrast agent., Materials and Methods: Six mongrel dogs were divided into three groups. In groups 1 and 2, anesthesia was maintained with pentobarbital. Group 2 also received an intravenous injection of atropine (0.03 mg/kg). In group 3, anesthesia was maintained with isoflurane (1.0%). Imaging was performed on a 1.5-T magnetic resonance (MR) imaging unit (one section per heart beat, a 30 x 15-cm field of view, 10-mm section thickness, and 64-kHz bandwidth). Region-of-interest (ROI) markers were placed on the blood pool of the left intraventricular cavity, anterior wall of the left ventricle, and anterior to the chest wall to track respiratory motion., Results: In group 1, the signal intensity (SI) periodically increased during each inspiration due to respiratory sinus arrhythmia. The relation between the SI increase and the variation of the delay between images was demonstrated in vitro and by computer simulations. No periodic increase of the SI was observed when regular cardiac rhythm was maintained by pharmacologic inhibition of the vagal-mediated chronotropic response with either the addition of atropine to pentobarbital or the use of isoflurane as the anesthetic agent., Conclusion: In an inversion-prepared fast GRE sequence, respiratory sinus arrhythmia can induce periodic SI increase by varying the respiratory rate interval and delay between images.

Organ procurement is the limiting factor in cadaver organ transplantation in France. The number of organs currently available is insufficient to meet demands while there are a sufficient number of potential donors. This critical situation has created difficult problems at all levels of the transplantation process: long waiting lists, discouraged patients, use of grafts of limited quality, selection of candidates on the basis of uncertain scientific criteria due to the lack of choice. This unsatisfactory situation after 30 years of successful transplantation raises many unanswered questions for decision makers including political leaders (the 1994 bioethics law will be revisited in this summer's session of parliament), health professionals (selection of candidates), hospital administrators (planning hospital structures) and ordinary individuals who are called upon to think about their own death. According to the data from the French graft control center, organs are not procured from approximately half of subjects in a state of brain death, because of refusal in 1 out of 3 cases. What is the meaning of this refusal? Solutions are available, what is lacking appears to be the will to solve the problem.

The current medical school curriculum in France includes a comprehensive examination on therapeutic management which medical students must pass before admission into residency. The proposed reform in the medical school curriculum considerably modifies the training program. The main objective is for students to acquire the minimal degree of responsibility necessary from the very beginning of residency, particularly in terms of therapeutic decision making. A survey currently being analyzed was conductec by the national association for training in therapeutics (APNET) and the national association of French medical students (ANEMF). It showed that at the end of pre-residence training, student demand for practical training in therapeutics and decision making is very strong. This round table revealed a consensus concerning the proposed reform. Faculty members, medical school deans, and students agree on the need for an improvement in training in therapeutics. The following points were discussed: what is the objective of training in therapeutics? When should it be taught? When should training be validated? And by whom?

Compared with other countries with a similar socio-economic environment, generic drugs account for a very small proportion of pharmaceutical sales in France. The recently promulgated law on financing the national healthcare system states that drug dispensers have the right to substitute generic drugs for prescription drugs in accordance with the drug equivalence repertoire established by the national drug agency. How patients, pharmacists, physicians and industrial firms will react to this new situation is an open question as use of generic drugs is basically unknown in France. Prescribing physicians, members of the drug agency, pharmacists, health economists, and insurance company and pharmaceutical firm representatives participated in a round table discussion to clarify the ongoing debate on the effect of this new cultural situation which calls an end to the French "exception" in drug consumption. The concept of generics and their use in substitution for prescription drugs was discussed in light of the outlined economic objectives together with the advantages and disadvantages patients and physicians can expect.

The objectives of this study were to define the relationship between the first order constant of Gd-DTPA transfer (K1) and the myocardial blood flow (MBF) at rest and to compare it with an equivalent relationship obtained for positron emission tomography (PET). In a canine model of permanent coronary occlusion (n = 4), myocardial and blood time concentration curves obtained by 13N-ammonia PET and Gd-DTPA-enhanced MRI were fitted by a one-compartment model to determine K1. A linear relationship was observed between MRI-derived K1 and MBF measured by microspheres (K1 = 0.88 x flow -0.015, R = 0.95), which compares favorably with the equivalent relationship derived from PET (K1 = 0.74 x flow +0.16, R = 0.88). The results of this preliminary study suggest that, at rest and distal to a permanently occluded coronary artery, myocardial perfusion quantification by MRI is possible and can challenge PET.

K1 (first-order transfer constant from arterial plasma to myocardium for Gd-DTPA) and Vd (distribution volume of Gd-DTPA in myocardium) were measured in vivo in a canine model (n = 5) using MRI-derived myocardial perfusion curves and a compartmental model. Perfusion curves were obtained after a bolus injection of Gd-DTPA (0.04 mM/kg) with an inversion-prepared fast gradient echo sequence. Myocardium and blood signal intensity were converted to a concentration of Gd-DTPA, according to a model appropriate for short (<1 s) interimage intervals characteristic of cardiac-triggered acquisitions. Before dipyridamole-induced stress, K1 and Vd, obtained from the fit of the MRI-derived perfusion curves, were 6.2 +/- 1.4 (mHz) and 17.5 +/- 4.2%, respectively. After dipyridamole infusion, a K1 increase of a factor of 2.82 +/- 0.72 was measured (P = 0.003). No change was observed in Vd (P = 0.98). These results suggest that the K1 increase after dipyridamole reflects a flow-related effect that can be useful to quantify the MRI-derived perfusion curves.

Rationale and Objectives: The authors investigated the usefulness of dynamic phosphorus-31 magnetic resonance (MR) spectroscopy in the assessment of hepatic function by studying the effect of a fructose load on a rat model of liver cirrhosis., Methods: In vivo P-31 MR liver spectra of eight rats with bile duct ligature and 10 control rats were obtained every 4.6 minutes before and after intraperitoneal fructose load (10 mmol per kilogram of body weight)., Results: In the basal spectra of the experimental group, the phosphomonoester peak was higher than in the control group (P = .026). After the fructose load, the phosphomonoester peak increase and the inorganic phosphate peak decrease were significantly less marked in the experimental group (P = .003). There was a linear correlation between the serum level of bilirubin and the phosphomonoester increase (r = .61, P < .001)., Conclusion: Dynamic P-31 MR spectroscopy may be useful in the assessment of hepatic function in chronic liver disease.

Objectives: People at high risk of colorectal cancer, due to familial or personal history, or to specific symptoms, are considered not to be concerned by mass screening by Haemoccult test. The aim of this study was to investigate people aged 50 to 74 with high risk of colorectal cancer among general practitioners' practices in the department of Calvados (France)., Methods: A random sample of 200 general practitioners were asked to systematically fill out a questionnaire on Haemoccult II proposal for 50-74 year-old patients for a whole week., Results: Participation rate of general practitioners was 58.5%. According to our findings, 13% of 50-74 years patients are considered not be concerned by mass screening, due to familial or personal history, or to specific symptoms., Conclusions: Colorectal cancer screening protocol have to be fit to level of risk of colorectal cancer. Involvement of general practitioners in colorectal cancer mass screening allows identification of high risk people who can then be managed with a more suitable screening protocol.

Rationale and Objectives: To evaluate whether decoupling improves signal-to-noise ratio and frequency resolution of in vivo kidney spectra, and to compare native and well-functioning transplant kidneys., Methods: Proton decoupling in conjunction with three-dimensional chemical shift imaging (3D-CSI) in phosphorus-31 magnetic resonance (MR) spectroscopy was used with a spatial resolution of 64 cm3 and 17-minute acquisition time to compare native (n = 10) and well-functioning transplant (n = 9) kidneys., Results: Proton decoupling improved peak amplitudes by almost 30%, as well as chemical shift resolution of in vivo kidney spectra. No statistically significant differences in phosphometabolite ratios and renal spectra were observed between healthy volunteers and patients with nonrejecting transplants. The phosphodiester-phosphomonoester ratio was 3.02 +/- 0.88, phosphomonoester-inorganic phosphate ratio was 1.07 +/- 0.44, and inorganic phosphate-adenosine triphosphate ratio was 0.58 +/- 0.22 after correction for saturation effects., Conclusion: Improved spectra of native and transplant kidneys can be obtained in vivo with MR spectroscopy by using a short acquisition time.

Background: Although several modeling strategies have been developed and validated for quantification of myocardial blood flow (MBF) from 13N-labeled ammonia positron emission tomographic data, a comparison of noise characteristics of the various techniques in serial studies is lacking., Methods and Results: Dynamic 13N-labeled ammonia positron emission tomographic imaging was performed at baseline and after pharmacologic stress in (1) single studies of four dogs with concomitant measurement of microsphere blood flow and (2) initial and follow-up studies of eight normal volunteers. Data were obtained from short-axis images for the blood pool and myocardial regions corresponding to the three arterial vascular territories. Indexes of MBF were obtained by four distinct techniques: (1) University of California, Los Angeles, two-compartment model, (2) Michigan two-compartment model, and (3) a one-compartment model with variable blood volume term. Coronary flow reserve (CFR) was measured as the ratio of stress/rest MBF. The estimated standard deviation of the measurement error for the relative change between studies of rest and stress MBF and CFR was determined for each technique. Estimates of MBF from all techniques showed good correlation with microsphere blood flow (r = 0.95 to 0.96) in canine myocardium. In human studies, similar mean estimates of MBF were found with all techniques. Techniques 1 and 3 showed the smallest interstudy variability in MBF and CFR. The estimated standard deviations for these techniques were approximately 20%, 30%, and 27% for rest MBF, stress MBF, and CFR, respectively., Conclusion: Noninvasive quantification of MBF and CFR from dynamic 13N-labeled ammonia positron emission tomography is most reproducible with technique 1 or 3. The ability to account for differences in myocardial partial volume gives preference to technique 3. However, substantial interstudy variability in regional MBF remains, suggesting the importance of procedural factors or real temporal fluctuations in MBF.

Treatment with 100 or 250 microM ZnCl2 irreversibly blocked neurotransmission in the Torpedo electric organ by inhibiting acetylcholine (ACh) release. In Zn2+-treated tissue, release failure did not result from impairment of Ca2+ entry since stimulation still provoked an accumulation of Ca2+. Also pretreatment of isolated synaptosomes with Zn2+ inhibited to the same extent the release elicited by KCl-evoked depolarisation and the release elicited by using the Ca2+ ionophore A23187. On the other hand, after application of A23187, Zn2+ by itself efficiently triggered ACh release from synaptosomes. This dual effect of Zn2+ was also observed to occur in proteoliposomes equipped with mediatophore (a protein of the presynaptic membrane characterised by its capability to support Ca2+-dependent transmitter release). Hence, Zn2+ mimicked two fundamental actions of Ca2+ on nerve terminals, which are: (1) the immediate activation of release, and (2) a more slowly developing desensitisation of release. Zn2+ was more powerful than Ca2+ for both actions. It is concluded that the dual action of Zn2+ on the mediatophore protein accounts at least in part for its complex effects on neurotransmission.

Objectives: Screening for colorectal cancer is a major public health problem in France as in most developed countries. Several controlled trials are on-going in Europe. The aim of the study was to determine requirements for success of mass-screening for colorectal cancer in France., Methods: A mass-screening program has been conducted between April 1991 and June 1994 in the department of Calvados for 164,364 people aged 45-74 years. The screening test was first proposed by general practitioners and occupational doctors during appointments. Secondly, a postal invitation to obtain the test, free of charge, by doctor or chemist, was sent., Results: Global participation rate was 43.4%; 40.2% of tests were distributed during the first phase, 47.1% during the second phase and 12.7% were distributed by a private health institute. Participation was higher for females (47.1%) than males (39.2%) and for urban districts (46.5%) than rural districts (24.4%). In case of positive test, colonoscopy has been more frequently achieved in urban districts and when test has been distributed by a physician. Positivity rate was 2.8%. Positive predictive value was 8.0% for a cancer and 13.5% for an adenoma larger than 1 cm. Because both positivity rate and positive predictive value were higher for males than females and increased with age, rate of cancer or large adenoma screened was almost three times higher for males than females and markedly increased with age., Conclusions: In France, different recruitment methods have to be used to reach a satisfactory participation to a mass-screening campaign. Such a program requires involvement of general practitioners and close coordination between practitioners and health care insurance agencies.