Absence of reproducibility of glycaemic excursions induced by identical meals in diabetic subjects connected with an artificial pancreas.
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Biomedical subjects
Publications and source records attributed to A Guillemart.
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Results of a collaborative study carried out in three different hospitals by nine surgeons are reported. Activity of a new scrub applied according to a standardized protocol was compared with that of the different scrubs and/or antiseptics customarily used by participating surgeons with their habitual method. Activity of products was evaluated by bacterial counts in gloves. Statistical analysis of results demonstrates the value of this trial design which compares scrubs under real conditions of use.
To compare the skeletal distribution of calcium and pyrophosphate complexes, autoradiograms of the growing zone of 10-week-old rabbit femurs were performed. Due to its stability to chemical and enzymatic hydrolysis and to the relatively long half-life of the isotope, 96Tc-labelled pyrophosphate was used. Calcium uptake was studied with carrier free 45Ca. For both tracers, the blood supply plays a significant role by delivering the radiopharmaceuticals. In a second step their partition was governed by mixing in different bone structures: calcium was incorporated inside the bone trabeculae and the mineral mass whereas labelled pyrophosphate remained in linear patterns surrounding bone spicules.
Autoradiograms were performed on brain slices, 3 h after 99mTc-pertechnetate injection, and 24 h after previous treatment with stannous pyrophosphate. On macroautoradiograms, the radioactivity was focused entirely upon plexus areas. Silver grains were predominantly overlying the cytosol of brush border cells; less than 10% of the total plexus radioactivity was found in vascular structures. These findings suggest that a possible metabolic phenomenon exists rather than a passive distribution.
The uptake of calcium-45 and of pyrophosphate labeled with the long-lived technetium-96 isotope were compared by means of liquid-emulsion microautoradiograms of the epiphyseal plates of 10-week-old rabbits, at 30 min, and 3 and 48 hr after i.v. administration. For both tracers, thin sections confirm the significant role of the blood supply, especially shortly after injection. However, other more specific mechanisms lead to a mixing of the calcium in the mineral mass and to a linear deposition of technetium facing the osteoid surfaces. These findings suggest that the tropism of tin-reduced technetium pyrophosphate is not governed by the mineral pool but rather by exchanges inside a still poorly calcified organic matrix.
For animal experimentation, the 95m and 96 technetium isotopes offer many advantages over technetium-99m. Their long physical half-lives and the emission of extranuclear electrons of low penetrating power make it possible to obtain autoradiograms of a great precision. The uptake of technetium stannous pyrophosphate by the epiphyseal plate was studied using liquid-emulsion microautoradiography, 3 hr after i.v. injection into 10-week-old rabbits. Microautoradiograms showed a well-defined and rather specific pattern of localization with intense uptake beneath the epiphyseal disk on the extremities of the vascular buds and a lack of accumulation in the cartilage, whether calcified or uncalcified. In the metaphysis, the label was located where new bone was being laid down and also over the cytoplasm of osteoclasts. We deduce from these results that in normal bone the general distribution of this tracer reflects mainly the arrangement of the blood supply, but the specific sites of accumulation are the bone-forming surfaces and the active resorbing osteoclasts.
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A total of 122 cases of various neurological diagnoses (among which 72 cerebral infarcts, 7 intracerebral hematomas and 38 intracranial tumors) had two separate brain scans, performed within 48 hours of each other after the administration of pertechnetate and technetium stannous pyrophosphate. The comparison of the resulting seans indicates that, in addition of an osseous accumulation, the pyrophosphate localizes greatly in ischemic cerebral lesions, especially those observed during the second week of evolution. It seems that the uptake of pyrophosphate reflects the area of anaerobic changes whereas the accumulation of pertechnetate depends on the disruption of the blood brain barrier. The scintigraphic diagnostic of cerebral infarctions is greatly improved.