Biomedical subjects
Publications and source records attributed to R Marty.
Eighty-nine women were examined using a flexible fiberscope and targeted biopsy was performed. Although the specimens were small (4 mm3 in maximum diameter), 80% reliability was obtained when specimens were compared with full curettage.
This is a report of our experience with a new flexible fibroscope, the CHF P 10. We performed more than 50 diagnostic endoscopies and 28 operative procedures. It is extremely practical to perform diagnostic and operative procedures at the same time if necessary. The major advantages of the new fibroscope are its diameter (4.9 mm), flexibility and bendable tip (260 degrees range). This permits a substantial decrease in cervical dilatation and use of anesthesia. Because of this, hospitalization costs decrease and the safety of surgical procedures is increased.
Two distinct categories of facts are deduced from a neuropathological study of the Ammon's horn, in particular the Sommer Sector, afflicted with alcoholic cirrhotic encephalopathy. In the pyramidal neurons of the CA1 layer, there are unquestionably paired filaments in a helical form, which correspond to the now classic "paired helical filaments". On the other hand, whereas the astrocyte population on the whole displays the characteristics of what can be called Alzheimer type II cells, a certain number of highly reactive areas persist, which can be detected by a GFAP-specific immunohistochemical method.
In human alcoholic cirrhotic encephalopathy, most of astrocytes of the cerebral cortex appear as Alzheimer type II cells. Thus, they cannot be visualized by the immunocytochemical detection of Glial Fibrillary Acidic protein (GFAP). However, fibrous astrocytes present in layer I of the cortex and in the vicinity of the white matter are GFAP positive. This special reactivity of layer I astrocytes could correspond to the persistance of the characters of primitive neuropil.
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The topographical variations in fiber size in the cochlear nerve of cat were quantitatively studied by electron microscopy. Measurements of fiber size as they appeared at the outlet of the spiral lamina show that fibers originating from the basal part of the cochlea are larger than those from the apex. When the diameter of apical fibers and their axoplasms at two different levels are compared, a significant variation in size is observed. As they appear in the internal acoustic meatus the apical fibers are larger at the level of the nerve trunk compared with the same fibers near the ganglion cell bodies. There are significant differences in fiber diameter with regard to their length for fibers derived from the apical turn. These results are compared with previous findings.
Early cortical neurogenesis and synaptogenesis are discussed with reference to observations made in fetal and postnatal rat temporal cortex. Thymidine autoradiography was used to determine the time of origin of cortical neurons, particularly of layer I. Earliest neurons--CRs--form between FD 12 and 15, whereas the period of maximal formation of layer I neurons other than CRs is situated between FD 17 and FD 19. Neurons destined for the deepest part of layer VI begin to form at FD 13. Both types of early-forming neurons develop synaptic contacts by FD 16. From this stage onwards, the temporal cortex taken as a whole continuously contains synaptic contacts. However, a more detailed analysis shows that some at least of the early formed synapses are transitory: for example, the CRs, which receive dendritic synapses on FD 16 and somatic synapses on FD 17, apparently lose most--if not all--of these contacts towards the end of fetal life. Whereas CRs develop an important protein producing equipment during the neonatal period, younger neurons located in the same (first) layer form dendritic, somatic and somatofugal synapses.
The unilateral resection have been done entirely or in part of the primary visual cortex in 10 cats with various postoperational delays. In all cases, some large and medium axons in the primary optic tract show signs of degeneration, leading to their disappearance along with an important glial reaction. As there in similar signs of degeneration, but apparently less important in all normal cats used for control, it is worth-while to reconsider the notion of retrograde transneuronal degeneration after cortical lesion.
Newborn rats received an intracisternal injection of 6-hydroxydopamine (100 micrograms) within 16 h after birth. Treatment effects upon noradrenaline uptake (with or without desmethylimipramine pre-incubation), endogenous noradrenaline, dopamine, and serotonin were biochemically assayed. Noradrenaline uptake and endogenous noradrenaline content were permanently reduced to less than 5% of control values. Reduction of endogenous dopamine content was less marked: at day 60, values were about 40% of controls. Serotonin content remained unaffected. Cell density countings in postnatal day 15 temporal cortex revealed an about 16% reduction in layers II and III of treated animals. These modifications of cortical geometry were discussed with reference to measurements of cortical thickness and ultrastructural observations on postnatal days 2, 5 and 15. Both supranormal involution and growth processes might result from the neurotoxin treatment. Whereas some of the degeneration processes might be due o general cytotoxic effects, this is less likely for the supranormal growth processes.
The Bodian method was used for an ultrastructural study on the optic nerve of the adult cat in order to compare the effects of two fixation techniques on the normal nerve and on the nerve during Wallerian degeneration after unilateral enucleation. Immersion fixation causes a predominately metallic deposit in the myelin sheath; the perfusion has no effect. During the Wallerian degeneration the two fixation methods lead to a metallic deposit located in the axon which is in large grains after immersion and extremely dense after perfusion. Various diffraction methods were used to identify the nature of the metallic deposit. These results emphasize the positive elements in systemically associating the electron microscope with the optic microscope for studies concerning Wallerian degeneration after metallic impregnation in the central nervous system
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An ultrastructural study of myelinated oligodendrocytes and aberrant myelin sheaths has been carried out on the corpus callosum of the adult rat, undergoing wallerian and retrograde degeneration. Abnormal myelin configurations appear under various forms and may be explained under different processes. In some cases, the collapsed myelin sheaths are closely apposed to the cell body of the oligodendrocyte while in others the sheaths surrounding the glial perikarya are described as redundant myelin sheaths issued from small neighbouring myelinated axons. In most instances, myelin of the compact type consisting of 1 to 5 lamellae or of splitted ones between which invades oligodendroglial cytoplasm, ensheaths completely the oligodendrocytes. Myelination de novo (that is, aberrant myelination) seems to be a correct interpretation of some enwrapping sheaths of myelin but for the other myelinated oligodendrocytes it is suggested that the glial cells penetrate inside previously formed myelin sheaths following the degeneration of the axon.
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A quantitative study was carried out on the adult cat optic nerve near the eyeball by systematically measuring the perimeters of all the axons seen through the optic microscope. The main purpose of this study was to define the topographical distribution of these axons in function of their size. Statistical studies show the existence of an area of maximal concentration of large axons in crescent form situated in the temporal zone of the nerve. The neurophysiological implications are discussed.
54 healthy cats were studied. In almost all cases, two types of degenerative signs could be seen: in the primary optic pathways, but also in the posterior funiculi and the spinal-cerebellar tracts, lesions of wide-diameter axons seen by their initial demyelination, accompanied by intense neuroglial reactions, and, on the other hand, a Wallerian degeneration of smaller axons situated in the axial part of the nerve. The percentage of these abnormalities must still be evaluated. Their eventual consequences and nature are discussed.
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The use of an experimental procedure based upon progressive postoperative delays allowed the quantification of the effects of enucleation performed at the ages of 2, 8 and 20 days, corresponding to key stages of the postnatal maturation of the optic nerve, namely premyelination, myelination and postmyelination. Two main events were noteworthy regarding cell reactivity. The higher the age of the animals at operation, the lower was the proliferation, and the larger was the time lapse between operation and the peak of proliferation. The interferences between reaction gliosis and myelination gliosis depended upon the developmental stage of the optic nerve. This reflects a progressive loss of plasticity.