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In order to determine and to demonstrate the cellular iron molecular states in hematopoietic bone marrow, direct investigations were performed by means of different and complementary spectroscopic techniques: optical absorption, electron spin resonance and Mössbauer spectrometry. In fact, the latter appears to have been the most informative. In addition to the hemoglobin forms, five- and six-coordination ligand protoporphyrins IX (monomeric and polymeric stacking, respectively) were observed. A small amount of non-hemic high-spin iron III storage component (ferritin) was measured. No diferric transferrin was detected. A ferrous compound was also observed and attributed to the mitochondrial iron pool.

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An animal model was proposed to clarify the difference in occurrence of enterocolitis in congenital aganglionosis. When gaseous distention of the colon was localized to the rectosigmoid area, enterocolitis never occurred. On the contrary, when it involved the left colon, enterocolitis occurred in 13 of 15 patients. Intestinal blood flow rates were simultaneously measured in the left colon and rectum of six dogs by using labeled microspheres and expressed in function of the intraluminal pressure. Results show that for elevated values of intraluminal pressure, blood flow was significantly lower in the left colon than in the rectum. These results may explain why ischemia and necrosis occurred more frequently in the left colon than in the rectum.

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Absorption 57Fe Mössbauer spectra have been carried out directly on fresh or lyophylized tissues of liver with either normal iron depot or iron overload. Two types of overloading have been studied: primary iron overload due to an excessive intestinal iron absorption and secondary iron overload (hemosiderosis) produced in beta-thalassemia patients by hypertransfusional therapeutics. The Mössbauer spectra, at room temperature, 77 and 4.2 K, on normal liver samples, are typical for the ferritin-hemosiderin compounds. In the spectra, performed on hemosiderosis liver samples, there appears, in addition to ferritin and hemosiderin, a new iron molecular environment, typical of high spin ferric iron and characterized by a superparamagnetic behaviour which begins at high temperature (above 77 K). This new component does not show up in the primary iron overload cases and seems characteristic of the physiological process which induces the iron overload.

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This work is a study of the radioinduced transformations undergone by intraglobular hemoglobin. Mössbauer spectrometry allows us to study in a wide range of doses the effect of X rays on deoxyhemoglobin as well as on oxyhemoglobin. Using this technique we have shown large differences between these two derivatives of hemoglobin. Deoxyhemoglobin leads to the formation of only one ferric nonheme compound while oxyhemoglobin produces this same compound as a last step after intermediary production of deoxyhemoglobin, methemoglobin, hemichromes, and hemochromes. We have also found that heat incubation and X rays have a similar effect on HbO2 except for the dissociation, which is absent in heat incubation. We have found a value for the energy needed for such a radiodissociation of HbO2 similar to that given by other authors utilizing other methods. Finally, we propose some explanations for the formation of the different compounds involved based on structural considerations.

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Emission Mössbauer spectra and Perturbed Angular Correlation measurements have been performed on samples of mineral bone powder labelled with 161Tb3+ or 133Ba2+ ions after either in vitro absorption or uptake by metabolic pathway. The study of these hyperfine spectra, compared with those carried out when 161Tb or 133Ba are situated in either hydroxyde lattice or phosphate one, shows that the uptake modes of rare-and alkaline-earth ions on the bone matrix are different. The rare earth ion seems to be absorbed on the surface bone in an environment of hydroxyl groups similar to the structure of a rare earth hydroxyde. The alkaline earth ion bone uptake appears more complicated and would make according to the following process : at first, surface absorption on the hydroxylapatite in a hydroxyde environment and then cationic exchange with the calcium phosphate groups into bone crystals.

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TDPAC measurements of the 356-81 keV gamma-ray cascade resulting from electron capture decay of 133Ba have been performed at room temperature on BaCl2 (aqueous solution and polycrystalline powder), and on samples where the 133Ba nucleus is bound to bone powder, and also to synthesised hydroxylapatite, all after absorption in vitro. As expected, the angular correlation is not perturbed in the solution. However, in the polycrystalline chloride the time dependence of the anisotropy of the cascade of 133Cs nuclide indicates that the decaying nucleus undergoes electric interactions due to different electric field gradients acting at the site of the nucleus. In 133Ba-bone powder the results show a static quadrupolar interaction differing with the absorption contact time during sample preparation, indicating that depth of 133Ba ion fixation in the bone crystal is dependent on this contact time. These results seem to be confirmed by the TDPAC measurements performed on 133Ba-hydroxylapatite samples where the contact times for absorption of active-ion 133Ba and hydroxylapatite in suspension were very different.

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By measuring cerebral blood volume (CBV) and intracranial pressure (ICP) variations at the same running time during sleep, it has been demonstrated that the ICP wave which appears during the REM sleep in hydrocephalic infants is produced by intracerebral vaso-dilatation. Nine infants with stabilized hydrocephalus were investigated by non-invasive means: REM phases were distinguished with the usual polysomnographic electrodes. Intracranial pressure was measured with a fontanel palpation transducer and CBV variations were obtained by recording 99mTc activity at the head level after in vivo labelling of red cells with 99mTc--pertechnetate. The time-activity curves, obtained from regions of interest and selected on the sequential radioisotope images, show that an increased ICP wave, occurring during the REM period, is related to a simultaneous increase in the blood volume, limited to the cerebral sector and not to the area of the external carotid artery.

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Comparison between the effective systemic ejection fraction defined by radiocardiography and cardiac chambers scanning, and the whole left ventricular ejection fraction calculated by cineangiocardiography allows an accurate assessment of mitral and aortic regurgitation extent. In case of both mitral and aortic insufficiency, each regurgitation can be quantitatively dissociated by means of the aortic isotopic dilution curve recorded at the same time as the radiocardiogram.

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