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Biomedical subjects

M H Epstein

Publications and source records attributed to M H Epstein.

At least 37 records · Page 2Linked to original sources
PubMed1994

Homework practices of general education teachers.

The purpose of this study was to survey the homework practices of general education teachers who teach students with disabilities. A national sample of 441 elementary, middle, and senior high teachers were asked about their homework practices, including their use of adaptations for students with disabilities. The results highlight homework practices and adaptations that are used frequently and perceived by teachers as helpful for students with disabilities. Also discussed are the differences in practices and adaptations across elementary, middle, and high school teachers, as well as the instructional implications of the identified homework practices for students with disabilities and their general education teachers.

Education, Special↗
PubMed1994

Prognostic implications of p53 overexpression in supratentorial astrocytic tumors.

The wild-type p53 gene is thought to play a critical role in tumor suppression and has been shown to reverse the transformed phenotype of tumor cells in vitro. Mutational inactivation of this aspect of p53 activity occurs frequently in many human neoplasms, including astrocytomas, and is thought to represent a critical step in tumor progression. We have found previously that the presence of p53 immunoreactivity was significantly associated with malignant astrocytomas arising in younger patients, although occurring infrequently in tumors in older patients. Given that young age is the most consistent clinical factor predictive of longer survival in patients with astrocytomas, this suggested that p53 protein accumulation might be a molecular predictor of enhanced survival. To test this hypothesis, we retrospectively studied the association of p53 overexpression with survival in 149 patients with astrocytomas, using univariate and multivariate analysis to determine its value in predicting survival. Although our analysis reaffirmed the strong association between young age and increased survival, we were unable to demonstrate any difference in survival between patients with Grade III and IV tumors with p53 immunoreactivity compared with those without. Presumably, once a tumor has progressed to high grade, the relative importance of p53 status as a predictor of survival is low, probably because of the large number of accumulated genetic alterations associated with malignant tumors. In contrast, the presence of p53 overexpression in Grade II astrocytomas seemed from survival curves to indicate shorter survival compared with patients who had no p53 immunoreactivity. However, this variable did not quite reach statistical significance (P = 0.08) as an independent predictive variable in multivariate analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Hydrocephalus decreases chloride efflux from the choroid plexus epithelium.

To explore the novel concept of intrinsic brain regulation of the choroid plexus (CP), we studied the function of the CP exposed to increased intracranial pressure (ICP). The function of the CP was evaluated by in vitro chloride (Cl-) efflux from isolated CP 21 days after kaolin induced hydrocephalus. The Cl- efflux was significantly decreased in animals with elevated intracranial pressure (rate constant, K = 0.024 +/- 0.001 s-1) and enlarged ventricles (K = 0.023 +/- 0.001 s-1) compared to sham animals (K = 0.031 +/- 0.001 s-1). In contrast, the Cl- efflux of CP from animals with normal ICP and ventricular size did not differ from sham animals. These results illustrate the first demonstration of regulation of the CP epithelial function with elevated ICP; they also suggest a brain-CP regulatory mechanism that alters CP function.

Animals↗
PubMed1993

Congenital anomaly of the second cervical vertebra predisposing to progressive cervical myelopathy. A case report.

The authors describe a previously unreported constellation of developmental anomalies of the C2 vertebra, which predisposed to the development of cervical myelopathy in a young patient. The embryology of the vertebral column is reviewed briefly, and the origin of each anomaly of the C2 vertebra is traced to one of the two early stages in development as follows: 1) the formation of the mesenchymal vertebra or 2) its induction to cartilage. This case emphasizes the importance of congenital stenosis in the development of cervical myelopathy in young patients. The outcome is favorable when it is treated aggressively.

Cervical Vertebrae↗
PubMed1992

Expression pattern of alpha-protein kinase C in human astrocytomas indicates a role in malignant progression.

Protein kinase C (PKC) is a family of isoenzymes which play an important role in regulating cell proliferation and differentiation. Constitutive activation of PKC, either by phorbol esters or overexpression of specific isoenzymes, leads to growth abnormalities in vitro and tumor promotion in vivo. Since stimulation of PKC in cultured astrocytes results in biochemical and morphological alterations associated with the transformed phenotype, we wanted to determine whether abnormal expression of specific isoenzymes of PKC was important in development of human astrocytomas in vivo. We have detected a specific pattern of alpha-PKC expression in human astrocytomas which is noteworthy because the highest transcript levels were detected in well-differentiated (Grade 1) tumors, with intermediate expression in anaplastic (Grade 2) astrocytomas and low or nondetectable levels in glioblastomas (Grade 3 astrocytomas) and normal controls. In comparison, the beta-PKC transcript was not detected in any of the tumors, while the gamma-PKC transcript was present in only one Grade 2 tumor. Immunohistochemistry, using a monoclonal antibody to alpha-PKC, revealed diffuse, positive cytoplasmic signals in most cells of the Grade 1 tumors. Grade 2 tumors exhibited heterogeneity of alpha-PKC expression, although a significant percentage of cells showed positivity. In contrast, only a small number of differentiated cells within Grade 3 tumors were positive for alpha-PKC expression, with the more malignant, dedifferentiated cells uniformly negative. Throughout all tumor grades, the staining pattern of alpha-PKC closely paralleled that of glial fibrillary acidic protein. Taken in conjunction with the established role of PKC in tumor promotion, these results suggest that the alpha-PKC isoenzyme plays a specific role in facilitating clonal expansion of transformed astrocytes in low-grade astrocytomas. Analysis of alpha-PKC may therefore serve as a direct biological marker of malignancy which may serve to enhance the current histopathological grading system.

Astrocytes↗
PubMed1992

Intramedullary epidermoid associated with an intramedullary spinal abscess secondary to a dermal sinus.

Intramedullary spinal abscesses are rare and potentially devastating lesions. A heightened clinical awareness of patients at risk is essential for an early diagnosis and intervention to improve the prognosis of these patients. The first case of spinal abscess was described in 1830, and only 63 cases have been reported subsequently. Intraspinal epidermoids also are unusual lesions. These tumors were reported first in 1829 and represent less than 1% of all intraspinal tumors. We present a case of a 2-year-old girl who had rapidly progressive paraplegia with urinary and bowel retention and was found to have an intramedullary epidermoid and an intramedullary abscess as a result of a dermal sinus. The association of an intramedullary abscess and epidermoid tumor, two rare lesions, has not been reported previously. We also review the literature related to both intramedullary epidermoids and intramedullary abscesses of the spinal cord. Advances in sectional imaging as described should help lead to an early and safe diagnosis of these rare but often debilitating lesions. This case illustrates the importance of a complete neurological assessment of all patients with a congenital dermal sinus because of the potential for intradural extension and the frequent association with other dysraphic abnormalities. Prophylactic surgery is indicated in many cases to prevent dangerous and recurrent infections of the central nervous system.

Abscess↗
PubMed1992

Thrombosis of difficult intracranial aneurysms by the endovascular placement of platinum-Dacron microcoils.

Patients with symptomatic aneurysms that are not excluded from the cerebral circulation have a poor prognosis. Standard treatment is surgical exploration with direct clipping of the aneurysm. Because of their large size or relationship to the base of the skull, some aneurysms may not be suitable for direct surgical clipping and may require alternative treatment modalities. A prospective clinical and radiological study of seven patients treated with the endovascular placement of platinum-Dacron microcoils to exclude the aneurysm from the cerebral circulation is reported. The seven patients ranged in age from 37 to 63 years; four were women. At completion of the endovascular procedure, total occlusion of the aneurysm with preservation of the parent artery had been achieved in four patients and 90% occlusion of the aneurysm in two. In the seventh patient, occlusion of the internal carotid artery resulted in the patient's death. At the 6-month follow-up review, both patients with an aneurysm less than 20 mm in size had persistent aneurysm thrombosis; however, the two patients with giant aneurysms had partial recanalization. Both required repeat thrombosis of their aneurysm with the placement of additional microcoils, one at 6 weeks and one at 6 months. These two patients have persistent aneurysm thrombosis at 12 months following their second procedure. The patient mortality rate for this study was 14%, while the procedure mortality/morbidity rate was 9%. It is concluded that thrombotic aneurysm therapy of difficult aneurysms is a safe procedure and will have a place in the treatment of selected aneurysms.

Adult↗
PubMed1992

Guest alliance: uses of state-level hospital discharge databases.

The applications of state-level hospital discharge data are increasing. SDOs, however, face several substantial challenges if they are truly to be perceived as a legitimate tool for managing the healthcare system. These challenges include obtaining a commitment at the state and national levels, and in the public and private sectors, to the following principles: promotion of the long-term stability of SDOs; expansion of state databases beyond hospitals into ambulatory and long term care settings; and provision of necessary financial, technical, and educational assistance so that SDOs can meet their legislative mandates. Stakeholders should be educated about the value of state-level data. SDOs should expand their dissemination efforts as a way of reinforcing the importance of placing data in the public domain. NAHDO is working with SDOs and other data collectors and users to improve uniformity, standardization, access, and use of health data.

Cost Control↗
PubMed1991

Nucleoside diphosphatase (NDPase) activity associated with human beta-protein amyloid fibers.

Nucleoside diphosphatase (NDPase) activity was studied by electron microscope cytochemistry in surgical specimens obtained from aged human cerebral cortices. The presence of NDPase activity on the surface of the microglial cells (MCs) and especially within the endoplasmic reticulum (ER) cisternae that are filled with amyloid fibers and that are in continuity with the extracellular amyloid deposits in plaques suggests a possible role of this enzyme in final elaboration of amyloid protein. The close structural relationship between MCs and amyloid plaques, suggesting the participation of these cells in the synthesis or final elaboration of amyloid fibers, was observed. The comparison of these observations with previously reported data on the distribution of NDPase in MCs and amyloid fibers in scrapie-infected mouse brain suggests that presumably similar mechanisms are acting in both cases. These observations, as compared with the results of other cytochemical and biochemical studies, also suggest that co-localization of NDPase activity with newly formed amyloid fibers in plaques can be associated with glycosyltransferase activities engaged in the amyloid or amyloid precursor protein glycosylation.

Acid Anhydride Hydrolases↗
PubMed1991

Potassium cotransport with sodium and chloride in the choroid plexus.

The effects of loop diuretics and ion substitution on the 2-min uptake of K (86Rb as marker) were analyzed to obtain evidence for K cotransport with Na and Cl in the choroid plexus epithelium. The isolated plexuses, which were excised from lateral ventricles of adult rats, were bathed in artificial cerebrospinal fluid (aCSF). At concentrations of 10(-6) to 10(-4) M, the specific cotransport inhibitors, bumetanide and piretanide, suppressed uptake of K in a dose-dependent manner. Ouabain-insensitive K uptake was stimulated by preincubating the choroid plexus in aCSF very low in [Na] and [K], then incubating it in much higher concentrations of these cations; bumetanide (10(-4)M) blocked this stimulated uptake by 52%. Moreover, tissue preincubation in Na- or Cl-free medium, followed by incubation with normal concentrations of both ions, stimulated the ouabain-insensitive uptake of K from 15 (baseline) to 35 nmol/mg dry weight. This stimulation of K transport depended on the simultaneous presence of both Na and Cl in aCSF, and replacing either ion alone did not stimulate the ouabain-insensitive K uptake. Collectively, these findings, together with those from a previous pharmacological study of 22Na and 36Cl transport, constitute strong evidence for the cotransport of Na, K, and Cl in rat choroid plexus.

Animals↗
PubMed1991

Psychopharmacological intervention. II: Teacher perceptions of psychotropic medication for students with learning disabilities.

The perceptions, knowledge, and opinions of 104 teachers of students with learning disabilities regarding medication used with their students were investigated. The students' doctors were perceived as the professionals primarily responsible for making the decision to have the student either placed on or taken off medication. The teachers indicated that global impressions and direct behavioral observations were used to assess the effects of medication but that they would prefer to use behavioral observations and rating scales. Hyperactivity and delusions/hallucinations were perceived as the problems most likely to lead to medication. Less than 15% of the teachers indicated that their professional preservice training had provided them with sufficient information on the use of medication for children with behavior problems, and less than 20% had a similar opinion regarding their inservice training on the same topic.

Attitude↗
PubMed1991

Social behavior of students who are seriously emotionally disturbed. A quantitative analysis of intervention studies.

The social behavior of students who are seriously emotionally disturbed sets them apart from their normative classroom peers. This article provides a quantitative analysis of intervention studies dealing with the social behavior of seriously emotionally disturbed students. Social behavior was broadly defined as including social skills deficits, behavior under inadequate stimulus control, and inappropriate behavior in the classroom. Of the 28 studies located, 11 dealt with some aspect of social skills and 17 with inappropriate classroom behavior. Each study was analyzed with respect to (a) the age, gender, and classification of the subjects; (b) the setting, referral source, and therapist; (c) the dependent and independent variables; (d) type of evaluation design used; (e) reliability of the dependent and independent variable; (f) social validation; (g) programmed generalization, maintenance, and follow-up; (h) measurement of collateral behaviors; (i) functional analysis of the target behavior; and (j) efficacy rating of the results on a 3-point scale. The results are presented and discussed in terms of current status and implications for future research.

Adolescent↗
PubMed1991

Cisterna magna microdialysis of 22Na to evaluate ion transport and cerebrospinal fluid dynamics.

Microdialysis is used in vivo for measuring compounds in brain interstitial fluid. The authors describe another application of this technique to the central nervous system, namely microprobe dialysis in the cisterna magna to study the dynamics of ion transport and cerebrospinal fluid (CSF) formation in the rat. The choroid plexus is the major source of CSF, which is produced by active transport of Na from blood into the cerebral ventricles. Formation of CSF is directly proportional to the blood-to-CSF transport of Na. By injecting 22Na into the systemic circulation and quantifying its movement into CSF by microdialysis, one can reliably estimate alterations in the rate of CSF formation. The sensitivity of this system was determined by administering acetazolamide, a standard inhibitor of CSF production. Because acetazolamide is known to decrease CSF formation by 40% to 50%, the cisternal microdialysis system in animals treated with this drug should detect a corresponding decrease in the amount of 22Na dialyzed. This hypothesis is supported by the 22Na uptake curves for control versus treated animals: that is, by the acetazolamide-induced average diminution of about 45% in both the rate and extent of tracer accession to dialysate. Bumetanide, a loop diuretic, reduced by 30% the 22Na entry into dialysate. Microprobe dialysis of fluid in the cisterna magna is thus a minimally invasive and economical method for evaluating effects of drugs and hormones on the choroid plexus-CSF system.

Acetazolamide↗
PubMed1990

Cotransport of sodium and chloride by the adult mammalian choroid plexus.

Cerebrospinal fluid formation stems primarily from the transport of Na and Cl in choroid plexus (CP). To characterize properties and modulation of choroidal transporters, we tested diuretics and other agents for ability to alter ion transport in vitro. Adult Sprague-Dawley rats were the source of CPs preincubated with drug for 20 min and then transferred to cerebrospinal fluid (CSF) medium containing 22Na or 36Cl with [3H]mannitol (extracellular correction). Complete base-line curves were established for cellular uptake of Na and Cl at 37 degrees C. The half-maximal uptake occurred at 12 s, so it was used to assess drug effects on rate of transport (nmol Na or Cl/mg CP). Bumetanide (10(-5) and 10(-4) M) decreased uptake of Na and Cl with maximal inhibition (up to 45%) at 10(-5) M. Another cotransport inhibitor, furosemide (10(-4) M), reduced transport of Na by 25% and Cl by 33%. However, acetazolamide (10(-4) M) and atriopeptin III (10(-7) M) significantly lowered uptake of Na (but not Cl), suggesting effect(s) other than on cotransport. The disulfonic stilbene 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS; 10(-4) M), known to inhibit Cl-HCO3 exchange, substantially reduced the transport of 36Cl. Bumetanide plus DIDS (both 10(-4) M) caused additive inhibition of 90% of Cl uptake, which provides strong evidence for the existence of both cotransport and antiport Cl carriers. Overall, this in vitro analysis, uncomplicated by variables of blood flow and neural tone, indicates the presence in rat CP of the cotransport of Na and Cl in addition to the established Na-H and Cl-HCO3 exchangers.

Acetazolamide↗
PubMed1989

Intracranial and spinal meningiomas in patients with breast carcinoma: case reports.

Breast carcinoma has a high predisposition to metastasize to the brain parenchyma or spinal epidural space with development of progressive neurological symptoms and signs and frequently death of the patient. We report 8 patients with known breast cancer who developed neurological symptoms attributable to an intracranial meningioma and 1 patient who developed spinal cord dysfunction resulting from a thoracic meningioma. The removal of the meningiomas resulted in return of normal neurological function in all patients. At follow-up, all our patients are alive without evidence of meningioma or breast carcinoma recurrence, except 1 patient who died of a metastatic malignant melanoma. This clinical association requires repeated emphasis because of the potential benefit in management of patients with suspected metastatic disease. We have reviewed and summarized the reported literature and added our 8 cases. The mean age of presentation before the second tumor was 6 years. Breast carcinoma was diagnosed first in 85% of cases. The clinical symptoms of the meningiomas were focal neurological signs in 50% of the patients, raised intracranial pressure in 40%, and a seizure in 10%.

Adult↗