Biomedical subjects
Publications and source records attributed to J Michaud.
A patient with a leiomyoma of the kidney was studied by ultrasound, intravenous pyelography and angiography. Only three renal leiomyomas have been investigated by angiography. The angiographic features of our patient's tumor differed from these others, being much more vascular with multiple tortuous vessels and an inhomogeneous capillary phase.
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There is substantial clinical and experimental evidence to suggest that ammonia toxicity is a major factor in the pathogenesis of hepatic encephalopathy associated with subacute and chronic liver disease. Ammonia levels in patients with severe liver disease are frequently found to be elevated both in blood and cerebrospinal fluid (csf). Hepatic encephalopathy results in neuropathological damage of a similar nature (Alzheimer type II astrocytosis) to that found in patients with congenital hyperammonemia resulting from inherited defects of urea cycle enzymes. Following portocaval anastomosis in the rat, blood ammonia concentration is increased 2-fold, and brain ammonia is found to be increased 2-3-fold. Administration of ammonia salts or resins to rats with a portocaval anastomosis results in coma and in Alzheimer type II astrocytosis. Since the CNS is devoid of effective urea cycle activity, ammonia removal by brain relies on glutamine formation. Cerebrospinal fluid and brain glutamine are found to be significantly elevated in cirrhotic patients with encephalopathy and in rats following portocaval anastomosis. In both cases, glutamine is found to be elevated in a region-dependent manner. Several mechanisms have been proposed to explain the neurotoxic action of ammonia. Such mechanisms include: Modification of blood-brain barrier transport; alterations of cerebral energy metabolism; direct actions on the neuronal membrane; and decreased synthesis of releasable glutamate, resulting in impaired glutamatergic neurotransmission.
We report a case of primary diffuse leptomeningeal gliomatosis documented by MR. The radiological findings guided the surgical biopsy toward the area involved. Pathological examination confirmed the diagnosis. The patient could consequently benefit from treatment, i.e., radiation therapy, which was followed by clinical relief.
A 3-year-old boy presented with headaches, vomiting, lethargy and papilledema. Communicating hydrocephalus along with transependymal fluid absorption and meningeal contrast enhancement was identified on CT. The enhancement was initially thought to be the result of a partially treated meningitis (child was previously on oral antibiotics for a presumed mycoplasma pneumonia). A right ventricular-peritoneal shunt was placed. CSF studies procured during the procedure were all normal. In contrast, CSF from a lumbar puncture contained a high protein, and cytology was highly suspicious for malignancy. Spine MRI showed diffuse leptomeningeal enhancement and a 1.5-cm intramedullary lesion at T12-L1 associated with minimal edema. The lesion was subtotally resected (70%) and diagnosed as an astrocytoma (mostly Kernohan grade 2 but with areas of grade 3). Chemotherapy was administered and follow-up spine MRI at 2 months did not reveal any residual tumor, however, the leptomeningeal enhancement persisted. Sixteen months later, at the completion of the chemotherapy and radiation therapy, the spine MRI remained unchanged. Neurological examination has always been normal. This case illustrates how a spinal cord astrocytoma can metastasize via spinocranial dispersion and present early with hydrocephalus rather than myelopathy.
Human myometrium and endometrium extracts processed separately could stimulate tritiated-thymidine incorporation into the DNA of cells with the fibroblast, myoblast and osteoblast phenotype. This effect was dose-dependent. Mitogenic activity of myometrial and endometrial extracts was acid stable and sensitive to tryptic digestion. In addition, mitogens of myometrial and of endometrial extracts were retained and could be eluted by 80% acetonitrile over 0.1% trifluoroacetic acid from cartridges of octadecylsilyl-silica. Reverse-phase high performance liquid chromatography (r-HPLC) separated fractions of myometrial extracts with broad cell and preferential cell type specificity from fractions with inhibitory activity for detector cells. Reverse-phase HPLC revealed the presence in endometrial extracts of various fractions with mitogenic activity for all detector cells. These growth and inhibitory factors could mediate important autocrine, paracrine and/or endocrine regulatory processes of human uterus.