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C Raffel

Publications and source records attributed to C Raffel.

72 records · Page 4Linked to original sources
PubMed1990

Reduction to homozygosity and gene amplification in central nervous system primitive neuroectodermal tumors of childhood.

The loss of genetic material from specific chromosomal locations has been identified for a number of pediatric tumors. This loss has been taken as evidence for the importance of tumor suppressor genes at these loci in the genesis of these tumors. One of these pediatric tumors, the primitive neuroectodermal tumor of the central nervous system, has not been well studied. In this report, an analysis of primitive neuroectodermal tumors for allelic deletions on chromosomes 1p, 7q, 10, 11p, 13q, and 17p has been performed. One of ten tumors was found to have increased copies of c-myc. Three different patients were found to reduce to homozygosity at one of three different locations. Significantly, however, three of nine informative patients showed a reduction to homozygosity on chromosome 17p. Thus, primitive neuroectodermal tumor is one of a growing number of tumor types in which deletions in the short arm of chromosome 17 might be important in oncogenesis.

Brain Neoplasms↗
PubMed1989

Benign brain stem lesions in pediatric patients with neurofibromatosis: case reports.

The symptoms and clinical courses of 4 patients with neurofibromatosis and lesions of the brain stem identifiable on computed tomographic and/or magnetic resonance imaging scans are described. Two patients underwent biopsy and both had low-grade astrocytomas with no evidence of anaplasia. Both received radiation and chemotherapy. The other 2 patients have been monitored without biopsy or treatment. Three patients are alive and clinically stable, having been followed up for an average of 4 years; neuroimaging studies have shown no change in their tumors. The fourth patient died of a supratentorial primitive neuroectodermal tumor. Imaging studies had shown no change in his brain stem lesion, which at autopsy was found to be a focal collection of fibrillary astrocytes. These data suggest that some patients with brain stem lesions and neurofibromatosis may have a prognosis distinctly different from that of the typical patient with a brain stem glioma. We recommend caution against aggressive operative and adjuvant therapy for brain stem lesions in patients with neurofibromatosis, unless progression of the lesion is documented clinically and/or by imaging.

Adolescent↗
PubMed1989

The effect of bromodeoxyuridine and ultraviolet light on 9L rat brain tumor cells.

Incorporation of the thymidine analog bromodeoxyuridine (BrdUrd) into DNA increases the sensitivity of a cell to uv light. We have examined the effect of uv light on cell killing and alkaline elution profiles in 9L rat brain tumor cells pretreated with BrdUrd. Combination treatment with BrdUrd and uv irradiation produced a dose enhancement ratio of 3.8 at the 10% survival level compared with uv-radiated control cells; cell killing depended on both the time of treatment and the concentration of BrdUrd used for incubation. Sequential treatment caused single-strand breaks and DNA-protein crosslinks in the portion of DNA containing BrdUrd; uv irradiation alone caused very few strand breaks and no DNA-protein crosslinks. Because of the presence of both lesions in cells treated with BrdUrd and uv light, it was possible to calculate crosslinking factors without using a charging X-ray dose to induce strand breaks, the method commonly used with crosslinking drugs. Results of repair studies suggested that single-strand breaks are repaired more rapidly than are DNA-protein crosslinks.

Animals↗
PubMed1988

Pituitary adenomas in Cushing's disease: do they arise from the intermediate lobe?

Pituitary adenomas from 15 patients with Cushing's disease were studied histopathologically. The tumors were examined for the presence of neural axons by the Bodian silver impregnation technique and a specific immunohistologic technique based on a monoclonal antibody to axonal neurofilaments. Axons were not seen in any of the surgical specimens. This finding suggests that most, if not all, adrenocorticotropin-secreting pituitary adenomas are of anterior lobe origin.

Adenoma↗
PubMed1988

To shunt or to fenestrate: which is the best surgical treatment for arachnoid cysts in pediatric patients?

The treatment options for intracranial arachnoid cysts are either craniotomy and fenestration of the cyst into the cerebrospinal fluid spaces or shunting of the cyst contents extracranially. Fenestration may eliminate the need to shunt, but it is a major operative procedure and is not always successful. To determine which treatment provides the greatest benefit with the fewest complications, the records of 31 patients with 34 arachnoid cysts treated at the Children's Hospital of Los Angeles between 1976 and 1986 were reviewed. The mean age of the patients was 4.4 years, with a range of 0 to 15.5 years. The most common location was the middle fossa (14 cases), followed by the posterior fossa (7 cases), the suprasellar region (5 cases), and hemispheric (5 cases) and other locations (3 cases). Signs and symptoms were related to abnormally rapid head growth in infants and to increased intracranial pressure and seizures in older children. The initial treatment of 29 cysts was fenestration. Twenty-two (76%) procedures were successful, with no additional treatment needed for the cyst. The other 7 cysts required the subsequent placement of a cystoperitoneal shunt. In 5 cases, the cysts were treated initially with cystoperitoneal shunts. Of the total 12 cystoperitoneal shunts, 5 have required revisions on one or more occasions. No significant difference in morbidity was noted between the two treatment options. Because we consider shunt independence to be a major goal of therapy, we suggest that patients with arachnoid cysts be divided into two categories, those presenting with associated hydrocephalus and those without hydrocephalus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Bromodeoxyuridine: a comparison of its photosensitizing and radiosensitizing properties.

The photo- and radiosensitizing properties of bromodeoxyuridine (BUdR) were assessed in vitro using the 9L rat brain tumor cell line. Pretreatment of 9L cells with 10 microM BUdR for 24 hours followed by irradiation with ultraviolet (UV) light resulted in a dose-enhancement ratio of 3.8:1 compared with UV radiation alone. X-radiation of BUdR-pretreated cells produced a dose-enhancement ratio of 1.7:1. Alkaline elution analysis of deoxyribonucleic acid (DNA) from cells treated with BUdR and UV irradiation showed the presence of DNA single-strand breaks and DNA-protein cross-links. Analysis of DNA from cells treated with BUdR and then x-irradiated showed no increase in DNA single-strand breaks compared with cells treated with x-radiation alone; no DNA-protein cross-links could be detected. The possible clinical relevance of these findings is discussed.

Animals↗
PubMed1988

Symptomatic hydrocephalus: initial findings in brainstem gliomas not detected on computed tomographic scans.

In a retrospective review of 85 patients younger than 18 years of age with a diagnosis of brainstem glioma treated between 1974 and 1987, seven (8.3%) initially had hydrocephalus and no evidence of tumor on CT scans. Intrinsic brain tumors, six in the pons and one in the diencephalon, were discovered later, either on follow-up CT scans or on magnetic resonance images obtained despite persistently normal CT scan findings. The initial radiologic study of choice for children and adolescents with hydrocephalus should be magnetic resonance imaging, including axial and sagittal T1- and T2-weighted images. If a CT scan is obtained first and hydrocephalus but not tumor is found, magnetic resonance image should be obtained to rule out the possible presence of an intrinsic brainstem tumor.

Adolescent↗
PubMed1985

Subarachnoid hemorrhage from a peripheral intracranial aneurysm associated with malignant glioma: report of a case.

The case of a patient who initially presented with a subarachnoid hemorrhage from an aneurysm of the distal left middle cerebral artery is reported. The aneurysm was later found to have occurred within a malignant glioma. Histological analysis showed tumor infiltrating the wall of the aneurysm. A causal relationship between growth of the tumor and development and rupture of the aneurysm is postulated.

Brain Neoplasms↗
PubMed1985

Cranial chordomas: clinical presentation and results of operative and radiation therapy in twenty-six patients.

The clinical presentation and the results of operative and radiation therapy in a series of 26 patients with cranial chordomas seen at the University of California, San Francisco, between 1940 and 1984 are reviewed. There were 14 men and 12 women, with a mean age of 39.6 years. Six patients had chondroid chordomas. The most common presenting symptoms were headache and diplopia, and the most common presenting sign was extraocular palsy. Fifty-three operations directed at removal of the tumor were performed. Twenty-three patients received various forms of radiation therapy postoperatively, including conventional external beam therapy, heavy charged particles, and interstitial implants. The average length of follow-up is 5.6 years. Eleven of 26 patients have died; the mean duration of survival in this group, excluding 1 perioperative death, was 4 years and 2 months. Although the average survival time of 6 years and 4 months was the same in patients with typical chordomas (excluding the perioperative death and 1 patient lost to follow-up) and in those with the chondroid variant, all of the latter are still alive, whereas more than half of the patients with typical chordoma have died.

Adolescent↗
PubMed1985

Postirradiation cerebellar glioma. Case report.

A 13-year-old girl developed an anaplastic astrocytoma of the cerebellum 7 years after irradiation of the central nervous system and prophylactic chemotherapy for acute lymphocytic leukemia. The fact that the astrocytoma was anaplastic and infiltrative was unusual for astroglial tumors at this site. It is proposed that this is a radiation-induced glioma.

Adolescent↗
PubMed1982

The relationship between endocytosis of concanavalin A and phytohaemagglutinin receptors and blast transformation, and direct identification of individual rabbit lymphocytes reactive to both mitogens.

Distribution and modulation of rabbit lymphocyte phytohaemagglutinin acceptors and concanavalin A acceptors during activation of rabbit lymphocytes have been examined by electron microscopy. Two types of cell surface acceptors have been tentatively identified, lectin binding acceptors that do not modulate, and receptors that are endocytosed when blast transformation is stimulated. All of the cells have binding acceptors for both lectins. Endocytosis correlates with early blast transformation and serves as an early marker for lymphocyte activation. When examined after 24 h of culture, those cells that undergo blast transformation contain endocytosed lectin receptors, whereas small untransformed cells do not. Capping prior to endocytosis is rarely observed. The mechanism whereby the signal for transformation is maintained after the reaction of lectin with cell surface receptors and transposed to the nucleus is not known. Although we conclude that endocytosis is an early event required for cell activation, it is possible that endocytosis is secondary to other activation events. By evaluation of sequential endocytosis, individual rabbit lymphocytes that endocytose only concanavalin A, only phytohaemagglutinin, both concanavalin A and phytohaemagglutinin, or neither lectin, have been identified.

Animals↗
PubMed1981

Surface immunoglobulin-bearing rabbit lymphocytes express both VH and L chain allotypic determinants.

The cell surface distributions of a locus and b lucus rabbit immunoglobulin allotypes have been examined simultaneously, using immunoelectronmicroscopic techniques. Most rabbit lymphocytes that bear surface immunoglobulin express both a and b markers. This is true of lymphocytes from blood, spleen, and lymph node of normal and immunized rabbits. A preponderance of cells bearing VH markers (a locus) but not L chain markers (b locus) was not observed.

Animals↗
PubMed1981

Individual rabbit peripheral blood lymphocytes reactive to anti-immunoglobulin and phytohemagglutinin or Concanavalin A identified by immunoelectronmicroscopic demonstration of endocytosis.

Individual rabbit lymphocytes reactive to phytohemagglutinin or Concanavalin A, and bearing membrane-associated surface immunoglobulin have been identified by electron microscopy. Endocytosis of lectin-lectin receptor complexes, which has previously been shown to be a marker for subsequent lectin-induced blast transformation was used as a marker for lectin reactivity. Surface immunoglobulin was detected by modified mixed antiglobulin (Coombs) technique. Lectin-reactive, sIg-bearing cells are well represented among lymphocytes from peripheral blood. Few of these cells, however, are found among lymphocytes isolated from spleen or popliteal lymph node. From these results it is suggested that some rabbit lymphocytes from peripheral blood share T cell (lectin reactivity) and B cell (bearing sIg) properties, or that reactivity to Con A is not an exclusive T cell property and sIg is not an exclusive property of B cells.

Animals↗
PubMed1974

Role for heme in mammalian protein synthesis: activation of an initiation factor.

Two nonerythropoietic tissues, brian and liver, contain an initiation factor that can overcome the block in initiation of protein synthesis seen in reticulocyte lysates when exogenous hemin is not present. Upon incubation of the brain factor with hemin and removal of free hemin by gel filtration, the factor activity is strongly stimulated. This stimulation shows a concentration dependence on hemin close to that seen for stimulation of protein synthesis in whole reticulocyte lysates. The data indicate that hemin mediates the formation of an active initiation factor complex from inactive, lower molecular weight components.

Animals↗
PubMedDate not supplied

Molecular biology of pediatric gliomas.

The genes involved in the genesis and progression of adult astrocytic tumors have been an area of considerable investigation. The tumor suppressor gene, p53, has been implicated, as has the epidermal growth factor receptor gene. Additional currently unidentified genes lie on chromosomes 10 and 19. Interestingly, work on pediatric astrocytomas suggests that the genes involved are different. p53 is rarely mutated in pediatric tumors, the epidermal growth factor receptor gene is rarely amplified or mutated, and chromosome 10 deletions are rare. The only pediatric tumor that seems to mimic the findings in adult tumors is brainstem glioma, perhaps explaining the uniformly grim prognosis in this type of tumor. In the pilocytic astrocytoma of childhood, mutations in the neurofibromatosis type I gene have been implicated in tumor development. In this review, the oncogenesis of pediatric gliomas is discussed and compared and contrasted to what is known about tumors.

Astrocytoma↗
PubMedDate not supplied

Central nervous system malformations and the VATER association.

Four patients with findings compatible with the VATER association having a malformation of the central nervous system requiring neurosurgical intervention are reviewed. Each patient has a different neurosurgical lesion, one of which has not been hitherto described as occurring with the other anomalies of the association. We suggest that all patients with the VATER association be evaluated carefully for malformations having neurosurgical implications.

Abnormalities, Multiple↗