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Biomedical subjects

P Carmel

Publications and source records attributed to P Carmel.

11 recordsLinked to original sources
PubMed1999

Some hypothalamic hamartomas contain transforming growth factor alpha, a puberty-inducing growth factor, but not luteinizing hormone-releasing hormone neurons.

Activation of LH-releasing hormone (LHRH) secretion, essential for the initiation of puberty, is brought about by the interaction of neurotransmitters and astroglia-derived substances. One of these substances, transforming growth factor alpha (TGFalpha), has been implicated as a facilitatory component of the glia-to-neuron signaling process controlling the onset of female puberty in rodents and nonhuman primates. Hypothalamic hamartomas (HH) are tumors frequently associated with precocious puberty in humans. The detection of LHRH-containing neurons in some hamartomas has led to the concept that hamartomas advance puberty because they contain an ectopic LHRH pulse generator. Examination of two HH associated with female sexual precocity revealed that neither tumor had LHRH neurons, but both contained astroglial cells expressing TGFalpha and its receptor. Thus, some HH may induce precocious puberty, not by secreting LHRH, but via the production of trophic factors--such as TGFalpha--able to activate the normal LHRH neuronal network in the patient's hypothalamus.

Astrocytes↗
PubMed1992

Immunohistochemistry and proliferative activity in Lhermitte-Duclos disease.

We have evaluated a recurrence of Lhermitte-Duclos disease by immunohistochemistry for Purkinje cell markers and proliferative activity (proliferating cell nuclear antigen), by electron microscopy and for DNA ploidy (image analysis). While most of the abnormal neurons in the lesion appear to be derived from granule cells, several Purkinje cell specific polyclonal and monoclonal antibodies, including L7, PEP 19 and calbindin, labeled a minor subpopulation. Staining with monoclonal antibodies to proliferating cell nuclear antigen and measuring cell DNA index and ploidy with a cell image analyzer revealed no proliferative activity. Electron microscopy findings were similar to those previously reported. In spite of its recurrence, our findings support the notion that Lhermitte-Duclos disease is malformative, not neoplastic, and that the characteristic neurons are derived predominantly but not exclusively from a non-Purkinje cell source, probably the granule cell.

Brain↗
PubMed1986

Myelination by transplanted fetal and neonatal oligodendrocytes in a dysmyelinating mutant.

Demyelination is a major feature of CNS injury and disease, including multiple sclerosis. To examine the potential for myelination by transplanted oligodendrocytes, initially described by Gumpel et al., we have transplanted neonatal cortex of mice with normal myelin into a dysmyelinating mutant, the shiverer mouse. We have found that oligodendrocyte precursors mature and synthesize myelin following transplantation. Immunostaining with antibodies to myelin basic protein (MBP), neurofilament protein and glial fibrillary acidic protein, demonstrates myelination both within the graft and extending out into the host, axonal sprouting from the graft which parallels the MBP-reactivity, and minimal astrocytic proliferation in response to the transplant.

Animals↗
PubMed1976

Autoradiographic localization of hormone-concentrating cells in the brain of the female rhesus monkey.

With autoradiographic procedures, cells which bind 3H-estradiol were found in preoptic, hypothalamic and limbic structures in the brains of ovariectomized, adult female rhesus monkeys. Estrogen-binding cells were seen in the medial preoptic area, medial anterior hypothalamus, ventromedial nucleus, and especially heavy labelling was seen throughout the extent of the arcuate (infundibular) nucleus of the hypothalamus. In limbic structures, cells in the bed nucleus of the stria terminalis and in the medial nucleus of the amygdala were well labelled. Systematic charting also revealed smaller numbers of estrogen-concentrating cells in other specific hypothalamic and limbic locations. In the anterior pituitary, significant numbers of basophils and acidophils were found to bind estrogen. Pars intermedia and the posterior lobe were virtually unlabelled. In the uterus, heavily labelled cells were seen in the endometrial stroma and in the myometrium. These autoradiographic findings agree with results of parallel biochemical experiments. In monkeys injected with 3H-corticosterone, the most extensive high-intensity binding found with autoradiography was in the hippocampus. Both pyramidal neurons and dentate gyrus granule cells were labelled. Biochemical experiments, also, showed highest cell nuclear accumulation of corticosterone in the hippocampus. Findings with estradiol in the rhesus monkey extend to primates conclusions based on autoradiographic experiments with steroid sex hormones in wide variety of vertebrates, including fish, amphibians, birds, and various mammalian species (Morell st al., '75a). All of these vertebrate forms have sex hormone-concentrating neurons, which are found in specific preoptic, hypothalamic and limbic structures. In the species studied, such hormone-concentrating neurons appear to be involved in the hormonal control of behavioral and pituitary function.

Animals↗
PubMedDate not supplied

Intraoperative functional MRI using a real-time neurosurgical navigation system.

A 42-year-old-man had focal left hand motor seizures. MR studies demonstrated a right posterior frontal brain tumor. Functional MRI was performed, localizing the motor cortex posterior to the lesion. The functional images were integrated with a neurosurgical navigation computer. A real-time intraoperative display of the anatomic and functional images was produced, registered to a neurosurgical probe. Excellent correlation was demonstrated between the functional maps and invasive electrophysiologic mapping performed at the time of craniotomy.

Adult↗
PubMedDate not supplied

Meningeal meningiomatosis in a child: case report.

We report a child with multifocal meningeal lesions demonstrating mixed meningiomatous histologic features. This lesion appears to have evolved over seven years, starting with a brief episode of garbled speech, nausea, and headache at 4.5 years of age. The child was then asymptomatic until 9 when she presented with bilateral leg weakness, in addition to her prior presenting symptoms and communicating hydrocephalus. Meningeal biopsies of two lesions were performed 18 months later. Immunohistochemistry and electron microscopy were needed to substantiate the histologic diagnosis. Radiation therapy to the craniospinal axis and corticosteroids were of some benefit, but more aggressive therapeutic modalities became necessary. The nosology of this lesion is discussed.

Adolescent↗