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Biomedical subjects

B L Maria

Publications and source records attributed to B L Maria.

At least 55 records · Page 3Linked to original sources
PubMed1993

Alternating skew on lateral gaze. Neuroanatomic pathway and relationship to superior oblique overaction.

BACKGROUND: Previous studies of patients with heterogeneous, often diffuse neurologic disorders concluded that the neurologic substrate for alternating skew on lateral gaze may be localized at the level of the brain stem tegmentum or the cervico-medullary junction, or both. The localized nature of brain tumors offers an opportunity to further investigate the anatomic localization for this as well as other conditions. METHODS: To test the hypothesis that cervico-medullary and cerebellar lesions are responsible for alternating skew on lateral gaze, the authors investigated a series of 50 children with brain tumors, 39 of whom showed neuro-ophthalmologic abnormalities on clinical testing. Seven children had alternating skew on lateral gaze. RESULTS: All seven children with alternating skew on lateral gaze showed neoplastic involvement at the level of the cervico-medullary junction and/or the cerebellum on critical analysis of neuro-imaging studies. CONCLUSION: The authors conclude that the neuroanatomic substrate for alternating skew on lateral gaze is localized at the level of the cervico-medullary junction and/or the cerebellum. Knowing that (1) alternating skew on lateral gaze closely mimics superior oblique overaction clinically, (2) superior oblique overaction is frequently found in patients with myelomeningocele, and (3) myelomeningocele is uniformly associated with Arnold-Chiari type II which includes cerebellar and cervico-medullary region abnormalities, the authors propose that alternating skew on lateral gaze and superior oblique overaction associated with myelomeningocele have similar neuroanatomic pathways.

Adolescent↗
PubMed1993

Do pediatricians independently manage common neurologic problems?

Quality educational programs should ensure that pediatricians possess current knowledge, skills, values, and attitudes in child neurology. The aim of this study was to examine the relationship between pediatricians' self-confidence in neurology and their frequency of referral of children to neurologists. We distributed a questionnaire to pediatricians and pediatric trainees for self-assessment of their (1) knowledge and skill in performing a neurologic examination, (2) ability to interpret neurologic findings, (3) knowledge of factual information about diseases of the nervous system, (4) ability to determine the need for investigations, and (5) ability to develop a positive attitude toward neurologic diseases. While pediatricians had significantly (P < .01) higher self-assessment scores than pediatric trainees, 54.2% of pediatricians referred 90% or more of their patients with neurologic complaints to neurologists; 74.9% of pediatricians referred more than 50% of such children to neurologists. Interestingly, pediatricians who referred over 90% of their patients to neurologists showed a significantly lower self-assessment score (P = .006) than did other pediatricians in knowledge and skill in performing a neurologic examination. As neurologists, we should develop educational programs that encourage pediatric trainees to learn to provide comprehensive care to children with common neurologic complaints.

Adult↗
PubMed1993

Brainstem glioma: I. Pathology, clinical features, and therapy.

Gliomas that arise in the brain stem have been associated with a poor prognosis. Diagnostic neuroimaging readily identifies the tumor as it extends between normal brainstem structures. Histologic sampling of tumor with stereotactic methods is notoriously unreliable in establishing a definitive prognosis. Clinical trials that incorporate high-dose chemotherapy, autologous bone marrow rescue, and irradiation hold promise of better tumor control by overcoming the inaccessibility of the central nervous system to standard doses of chemotherapy. We review the pathology, clinical features, neuroimaging features, and current therapeutic concepts relative to brainstem glioma. The pediatric neurologist has a pivotal role in identifying and monitoring children with this malignancy.

Biopsy↗
PubMed1993

Brainstem and other malignant gliomas: II. Possible mechanisms of brain infiltration by tumor cells.

Gliomas that arise in the brain stem and other malignant gliomas constitute approximately 60% of all brain tumors and have eluded effective therapy, in part because they are able to infiltrate the normal brain. Histopathologic studies have confirmed the presence of infiltrating tumor cells very distant from the glioma mass. We review the neuroimaging and pathologic features of glioma-cell infiltration and some of the complex cellular and biochemical determinants of tumor-cell motility and invasiveness. Understanding how glioma cells become motile and invasive is pivotal to therapeutically targeting the machinery that enables gliomas to infiltrate the brain.

Brain Stem↗
PubMed1993

Severe permanent encephalopathy in acute lymphoblastic leukemia.

As survival rates for childhood acute lymphoblastic leukemia have increased, concerns over improved quality-of-life have also increased. Although 3-10% of children may experience acute transient neurotoxicity during induction chemotherapy, they are felt to be at low risk for late sequelae. We report three previously healthy boys with newly-diagnosed acute lymphoblastic leukemia who presented with obtundation and severe seizures during late induction with a standard four drug chemotherapy regimen. While all three are disease-free survivors, they unexpectedly have persistent and medically intractable partial complex seizures, broad-based neuropsychological impairment and striking neuroimaging abnormalities. These findings suggest that children with leukemia who develop an acute encephalopathy during induction chemotherapy are at risk for long-term neurological and neuropsychological sequelae, despite the cessation of further potentially neurotoxic therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Intraventricular alpha interferon therapy for Rasmussen's syndrome.

A 4-year-old boy developed Rasmussen's syndrome and was treated with alpha interferon intraventricularly. An improvement in the epileptic and neurologic syndrome was noted for several weeks following interferon. No adverse side effects were encountered. Since hemispherectomy is the only established therapy in Rasmussen's Syndrome, further studies are needed to establish if intraventricular alpha interferon may halt the clinical progression of the syndrome.

Atrophy↗
PubMed1992

Brain tumors in children and adolescents--III. Effects of radiation and hormone status on intelligence and on working, associative and serial-order memory.

The effects on intelligence and memory of two post-surgical conditions (radiation treatment, hormone deficiency and supplementation) were explored in 46 children and adolescents with tumors in a variety of brain sites. Verbal intelligence, but not non-verbal intelligence, varied positively with age at radiation treatment. Memory for word meanings was unrelated to either radiation history or to hormone status. Severe deficits in serial position memory occurred with impaired hormone function and an older age at tumor onset. Severe deficits in working memory were associated with a history of radiation and a principal tumor site that involved thalamic/epithalamic brain regions. Radiation treatment and hormone status affect later cognitive function in children and adolescents with brain tumors. Although the greater vulnerability of the verbal intelligence of the younger radiated child and the serial order memory of the child with later tumor onset and hormone disturbances remain to be explained, and although the form of the relationship between radiation and tumor site is not fully understood, the data highlight the need to consider the cognitive consequences of pediatric brain tumors according to a set of markers that include maturational rate, hormone status, radiation history, and principal site of the tumor.

Adolescent↗
PubMed1992

Crown of microfilaments in the extending cytoplasmic processes of medulloblastoma glial progenitors.

Microfilaments and microtubules play a part in the extension of neuronal processes but their roles in the formation of glial processes have not yet been determined. The objectives of this study were to determine the organization of microfilaments in differentiating glial progenitors (RB2 cells) and to study the effects of microfilament or microtubule disruption on process extension. Intense F-actin staining (crown of microfilaments) was observed at the leading edge of a small extending conical tip in differentiating RB2 cells, but was absent in process-bearing TE671 rhabdomyosarcoma cells. No significant difference was noted in the mean number of TE671 cells with processes treated with a microfilament disrupter from that of similarly treated controls. In contrast, a significant difference was noted in the mean number of RB2 cells with processes after microfilament disruption treatment from that of similarly treated controls. Microtubule disruption arrested extension and caused process retraction in both cell types. The results of this study demonstrate that microtubules play an equally important part in the extension and stabilization of the RB2 and TE671 processes. Moreover, the crown of microfilaments concentrated in the glial RB2 process (and not in the TE671 process) may be critical to its extension during differentiation.

Actin Cytoskeleton↗
PubMed1992

Suprasellar tumors of maldevelopmental origin in Klinefelter's syndrome. A report of two cases.

Patients with Klinefelter's syndrome may have a predisposition for the development of neoplasia, particularly extragonadal germ-cell tumors, but a suprasellar location is rarely reported. The clinical and neuroradiologic features in two patients with Klinefelter's syndrome and dysmorphic suprasellar masses of maldevelopmental origin (presumably lipomas or lipodermoids) are described. One patient had bilateral optic atrophy and decreased vision. To our knowledge, only one similar case (a suprasellar hamartoma) has been previously reported in association with Klinefelter's syndrome.

Brain Neoplasms↗
PubMed1991

Efficacy of postoperative chemotherapy using cisplatin plus etoposide in young children with brain tumors.

Neuraxis radiation therapy (RT) for primary intracranial tumors is associated with major late effects if administered to very young children. To control residual tumor and to delay RT, we treated eight young children (median age 6.5 months) with primary central nervous system (CNS) tumors using combination chemotherapy: cisplatin, 20 mg/M2/day plus VP-16, 75 mg/M2/day i.v. for 5 days, given q. 3-6 weeks for 8 cycles. The tumors were medulloblastoma (one), malignant ependymoma (two), primitive neuroectodermal tumor PNET (two), malignant glioma (two), astrocytoma (one). Six had measurable disease; three had positive cerebrospinal fluid (CSF) cytopathology. All patients with measurable tumor had initial objective responses (three) complete response [CR], one partial response [PR], two minor response [MR], including cytopathology (three CR of three) and metastatic deposits (two CR of two). One patient relapsed during chemotherapy. Median time to disease progression was 17.5 months; median survival was 34 months. Three patients, none of whom received RT, have prolonged progression-free intervals of 47-67 months to date. Neurodevelopmental progress continued during and after chemotherapy. Chemotherapy toxicity was mild. Median neutrophil nadir was 312/mm3, platelets 72,000. Fever during neutropenia occurred in six of 61 courses. Moderate high-frequency auditory losses were detected in three patients, and mild renal injury (GFR less than 70 ml/min) was detected in two of seven evaluable children. This pilot study demonstrates the apparent efficacy and mild toxicity of 5 day courses of cisplatin plus VP-16, with delayed RT, in young children with CNS neoplasms. A POG treatment protocol that incorporates cisplatin plus VP-16 is evaluating primary chemotherapy with delayed radiotherapy in larger numbers of pediatric brain tumor patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Dibutyryl cyclic AMP induces vimentin and GFAP expression in cultured medulloblastoma cells.

Evidence for the astrocytic lineage in medulloblastomas rests largely on the detection of the glial fibrillary acidic protein (GFAP) from which intermediate filaments (IF) specific for astrocytes are assembled. Astrocyte progenitor cells from the mouse neopallium however express another IF protein, vimentin, before they acquire GFAP in vivo and in vitro. The purpose of the current study was to determine if cells obtained from a focally GFAP-positive posterior fossa medulloblastoma previously shown to acquire GFAP in response to dibutyryl cyclic AMP (dBcAMP), also express vimentin before expressing GFAP. More than 80% of cells in the tumor section contained vimentin while fewer than 1% of cells contained GFAP; occasional clusters of malignant GFAP-positive cells and clusters of cells negative for both vimentin and GFAP were also identified in the tumor. One hundred per cent of cultured cells in the first 10 passages from the tumor contained vimentin and no cells expressed GFAP. When cells were cultured in the presence of dBcAMP. Western immunoblotting showed an increase in vimentin which reached maximal values within 24 h followed by an increase in GFAP which reached maximal values at 72 h. The increase in vimentin followed by that of GFAP in cultured medulloblastoma cells has not previously been reported and suggests that most astrocyte progenitors which are derived from medulloblastoma and cultured in vitro may be at a developmental stage which corresponds to the proastroblast stage in the developing mouse brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Bucladesine↗
PubMed1989

The modulation of astrocytic differentiation in cells derived from a medulloblastoma surgical specimen.

Medulloblastomas are cerebellar tumors which are primarily composed of sheets of uniform, small malignant cells and may have astrocytic, neuronal or no features typical of these cell types. The assessment of astrocytic differentiation in medulloblastoma rests largely on the detection in malignant cells of glial fibrillary acidic protein (GFAP), a marker present in the later stages of normal astrocyte differentiation. It is still not known whether cells that do not contain GFAP in medulloblastomas with astrocytic differentiation correspond to highly proliferative astrocyte progenitors in maturation arrest at earlier stages of differentiation. The purpose of the current study was to examine whether cells in short term culture derived from a medulloblastoma tumor specimen with astrocytic differentiation were of the astrocytic lineage and if so, whether they represented proliferative astrocyte progenitors which would morphologically and antigenically mature in response to differentiating agents. A portion of tumor specimen from a 10-month-old child with recurrent posterior fossa medulloblastoma (RB2) that contained GFAP focally in tumor cells was grown in monolayer culture. We examined cellular structure and appearance of western immunoblotting and immunohistochemical studies for GFAP and neuron-specific enolase (NSE) in RB2 cells before and after treatment with retinoic acid (RA) and dibutyryl cyclic AMP (dBcAMP). RB2 in culture consisted of small polygonal cells (93%), large flat cells (3%), and polygonal cells with cytoplasmic processes (4%). In untreated RB2, 30% of cells expressed GFAP and staining for NSE was negative. RA treatment produced flattened cells and decreased GFAP. DBcAMP reversibly induced fine cytoplasmic processes containing GFAP in 85% of cells within 96 h. Neither agent induced NSE. The results suggest that cultured cells which are derived from a medulloblastoma with astrocytic differentiation do not spontaneously differentiate but that treatment with dBcAMP suppresses proliferation, enhances cytoplasmic process formation and increases cytoplasmic GFAP. Cells in culture and in medulloblastoma tumor specimens which do not contain GFAP may represent astrocyte progenitors in maturation arrest.

Astrocytes↗
PubMed1987

Cervicomedullary compression in young patients with achondroplasia: value of comprehensive neurologic and respiratory evaluation.

We studied prospectively 26 young patients with achondroplasia to test two hypotheses: that respiratory problems may be the result of occult spinal cord compression, and that achondroplastic patients with cord compression might have occult respiratory abnormalities. Respiratory abnormalities were present in 85%, the majority caused by a primary problem of the pulmonary system, such as small thoracic cage or obstructed airway. Three patients had hypoxemia, recurrent cyanotic spells, and episodes of respiratory distress explainable only by cervicomedullary cord compression; in each patient, respiratory problems were alleviated by decompressive surgery. Another six patients with cervicomedullary compression had, in addition, at least one primary pulmonary cause of respiratory problems. After decompressive surgery the respiratory problems improved in three and were unchanged in three. Reconstructed sagittal CT images proved the most sensitive technique for detecting craniocervical stenosis as a cause of cervicomedullary cord compression, although some degree of stenosis was present in nearly all of the patients.

Achondroplasia↗
PubMed1987

Dandy-Walker syndrome revisited.

The Dandy-Walker syndrome is said to be associated with a high incidence of mental retardation and motor dysfunction leading some to suggest termination of the affected fetus in utero. Since this view seemed contrary to our experience, we reviewed 19 patients with the Dandy-Walker syndrome diagnosed from 1966 to 1983. Thirteen patients with Dandy-Walker syndrome were diagnosed before 6 months of age and followed for more than 2 years (mean: 10 years). In the absence of other associated major abnormalities, 7 of 8 (88%) are functioning well and have attended regular schools. Two of these seven have had special help with isolated learning problems. None of these patients have significant motor disability. One additional patient with normal intellectual and motor function died of acute shunt malfunction. In the remaining 4 patients with Dandy-Walker-associated abnormalities, 3 (75%) have severe intellectual retardation and spastic cerebral palsy. Five of six patients (83%) with Dandy-Walker syndrome diagnosed after 6 months of age are normal. The outcome of patients with Dandy-Walker syndrome appears far better than previously reported.

Adolescent↗
PubMed1986

Diffuse leptomeningeal seeding from a malignant spinal cord astrocytoma in a child with neurofibromatosis.

A 5-year-old child typical clinical features of neurofibromatosis presented with a history of suspected basilar meningitis and CT findings of enlarged optic nerves and an expanding left cavernous sinus mass. CSF cytologies and meningeal biopsy were unremarkable. At craniotomy, a mass confluent with the left trigeminal nerve was resected which had histologic characteristics of a nerve sheath tumor but was GFAP (glial fibrillary acidic protein) stain positive. Postmortem examination, 1 month following surgical resection, demonstrated a clinically unsuspected primary thoracic spinal cord astrocytoma with dissemination throughout the subarachnoid space, invasion of the trigeminal nerve and encasement of other cranio-spinal nerves. This unusual case emphasizes the occurrence of leptomeningeal spread in a clinically silent spinal cord glioma and the diagnostic value of immunohistochemistry.

Brain↗