Biomedical subjects
Publications and source records attributed to J Poirier.
A 53-year-old patient with Wilsons's disease and without autonomic dysfunction presented on T2-weighted MR study an atypical decreased signal intensity of the putamina and the caudate nuclei. Possible explanations of such a signal abnormalities are discussed.
Evidence is given for altered gene expression of gamma-actin in the hippocampus in response to entorhinal cortex lesion (ECL). Time course analysis reveals a progressive repression of gamma-actin expression between 4 and 14 days post-lesion, coinciding with the early and middle phases of the hippocampal reinnervation process. RNA prevalence returns to near control values at 30 days post-lesion. Corticosterone administration, which is known to impair the reinnervation process in ECL rats, prevents the lesion-induced reduction in gamma-actin expression and blocks the induction of alpha 1-tubulin in the deafferented hippocampus. The timing of response of gamma-actin to ECL and its modulation by glucocorticoid administration support suggestions that gamma-actin has an important role to play in neuronal cytoarchitecture remodelling during hippocampal reinnervation.
A case of multiple vertebral hemangiomas with progressive neurological deficit is presented. Successful treatment was accomplished using preoperative embolization, palliative surgical decompression, and postoperative radiation therapy. The patient has remained asymptomatic for 6 years. The authors review the role of current imaging modalities and options for therapeutic intervention. Preoperative embolization, palliative surgical decompression, and postoperative radiotherapy appear to provide a satisfactory outcome in patients with multiple hemangiomas and may represent an effective alternative to more aggressive surgical intervention.
Hemosiderin deposition and vascular inflammation were evaluated in muscle specimens from 50 human immunodeficiency virus (HIV)-infected individuals with neuromuscular symptoms. Iron deposits were detected in 25 of 50 cases, and were found more frequently in the distal muscles of lower limbs than in proximal muscles (22 of 30 cases v three of 20 cases; P less than .001). The incidence was higher than in controls (P less than .01). Polyarteritis nodosa was observed in three cases and microvascular inflammation was observed in 27. Direct immunofluorescence showed deposits of both immunoglobulins (mainly immunoglobulin M) and complement in small vessel walls of 19 of 34 patients. The p17 and p24 HIV antigens were detected in three of 27 cases. Both T8 lymphocytes and macrophages were significantly more numerous in patients with Perls'-positive material; these patients also showed vascular inflammation more frequently. Other findings included noninflammatory microangiopathy (18 cases), tubuloreticular inclusions in endothelial cells (one case), and free and intracytoplasmic eosinophilic globules likely representing digested erythrocytes (seven cases). The present study shows that iron pigment deposition in skeletal muscle is a nonspecific finding, frequently observed in the lower extremities of HIV-infected individuals, where it reflects immunopathologic alterations of the microcirculation. Erythrophagocytosis, which may be observed in the muscle of some HIV-infected individuals, may also be implicated.
Evidence is given for altered gene expression in the hippocampus in response to entorhinal cortex lesioning. Three RNA markers encoding glial fibrillary acidic protein, apolipoprotein E and alpha-tubulin were isolated from a rat hippocampal cDNA library by differential screening with cDNA probes from entorhinal cortex lesioned and control rat hippocampus RNA. By Northern blot analysis, mRNA for apolipoprotein E and alpha-tubulin increased to peak around 6 days after the lesion and returned to near control level at 30 days. The increased synthesis of both mRNAs coincides with the acute phase of synaptogenesis, protein synthesis, and polyribosomes accumulation in the deafferented hippocampal area.
Entorhinal cortex lesions (ECL) that damage the perforant path to the hippocampus induce rapid increases of apolipoprotein E (apo E) mRNA in the hippocampus. Apo E mRNA was localized in astrocytes by in situ hybridization in combination with immunocytochemistry for glial fibrillary acidic protein (GFAP). Unilateral ECL also increased hippocampal GFAP mRNA, with increases preceding those of apo E mRNA. The apo E mRNA and GFAP mRNA responses were transiently bilateral in non-denervated zones. The timing of response in apo E mRNA to deafferentation supports suggestions that apo E has roles in membrane remodelling during responses to neuron injury.
A hippocampal poly(A) RNA, pADHC-9, was cloned by differential screening of a human hippocampal cDNA library. By RNA blot analysis, pADHC-9 was elevated 2-fold in Alzheimer's disease hippocampus. In situ analyses identified pADHC-9 expression in pyramidal and non-pyramidal cells of the hippocampus and entorhinal cortex. Nucleotide sequence analysis identified pADHC-9 as a potential human homolog of rat sulfated glycoprotein 2 (SGP-2). SGP-2 expression increased in rat hippocampus following experimental lesions that mimic intrinsic neuronal loss and/or deafferentation. The function of pADHC-9 in brain has not been defined, but in serum, a similar protein inhibits complement-dependent cytolysis. Increased expression of pADHC-9 in Alzheimer's disease hippocampus may be a compensatory response mounted to retard a complement-driven neurodegenerative cascade.
In vitro translation products from RNA of rat hippocampus after deafferentation by entorhinal cortex lesions were analyzed by two-dimensional gel electrophoresis. Although hippocampal total RNA yield was not affected 14 days after the lesion, analysis of the gels showed reproducible changes in the steady-state level of several transcripts. Glial fibrillary acidic protein RNA increased 2-fold over control hippocampi RNA. Moreover, seven other transcripts of unknown identity had increased prevalence in the denervated hippocampus. The changes, which ranged from 2- to 20-fold, involved mRNA encoding small slightly acidic polypeptides: 12 kDa (pI 5.6), 13 kDa (pI 6.1), 20 kDa (pI 5.8), 31 kDa (pI 5.7), 33 kDa (pI 5.7), 35 kDa (pI 5.6), and 53 kDa (pI 5.4). These results suggest new molecular markers for analyzing the complex mechanisms of synaptic reorganization in the dentate gyrus after deafferentation.
Preliminary electron microprobe studies of a small number of meningiomas, oligodendrogliomas, glioblastoma multiformae, craniopharyngiomas, and metastatic epithelioma of the breast suggest that the elemental composition of the deposits associated with these tumors is characteristic for each type of tumor.
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Twenty-three dogs underwent a complete transection of the spinal cord at L 1 level. Section was followed in eighteen animals by reconstruction effected through suture of the arachnoide with the aid of monofilament 10 X 0 thread. The operation was in all cases concluded by an osteosynthesis with metallic material in order to prevent any movements in the operated site, and a tight dural closure was achieved in order to prevent propagation of any epidural hematoma or secondary granuloma. This technique did not prevent an unfavorable evolution of the suture, which demonstrated three different morphological features:--necrosis of the spinal cord cut ends with secondary formation of a transverse cyst;--secondary infiltration of the operated focus by a fibrous scar growing from the inner aspect of the dura;--failure of axon regeneration through this fibrous block in spite of noteworthy proliferation of axons coming from the dorsal roots. A critical analysis of those results led to a comparaison with various previous works on the same subject. The most recent of these works have led to promising prospects which need confirmation.
A report on a case of herpes encephalitis in a patient of particularly high intellectual level who was kept under observation for a period of 13 years. Anatomical examination of the brain demonstrated massive bilateral destruction of the limbic system. Having studied the higher functions of this patient for many months it was possible to establish interesting correlations relating to the role of the limbic system. It appears to be indispensable for the utilization of verbal, praxognosic, and conceptual information. Though this is still retained in the intact neocortex, mobilization of the information is possible only when stimuli arise from the exterior and for as long as they last. Spontaneous evocation of this data is, in fact, impossible, as is the stocking of new information. The limbic system, therefore, while not being the site of retention of memorised informations which is the role of the neocortex, appears to be a logic system. Which is indispensable for proper functioning of the memory machine.
SPD calcifications from four cases of Fahr's disease were studied with an electron microprobe of Castaing, and found to contain different elements, among them Zn, Al, Mg. The presence of the elements is underlined not because of presumption as to their importance on the pathogenesis of this disease, but because of their rare identification in cerebral calcifications. A1 and Mg have been localized previously in cerebral calcification, but this is the first report of morphological localization of a high concentration of zinc in the brain. Two of these cases had hypoparathyroidism.
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The introduction of the concept of intermittent mandatory ventilation (IMV) has meant that for the first time weaning is controlled. The abrupt cessation of ventilatory support, even for short periods, as was obligatory before IMV, is no longer necessary. The frequency of positive pressure inflations can be gradually and progressively decreased as indicated, leading to spontaneous ventilation in a planned, controlled program. The ease with which other artificial ventilation technics may be incorporated into this system adds to its usefulness. IMV should be considered whenever ventilatory support is to be discontinued.
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