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Biomedical subjects

M A Epstein

Publications and source records attributed to M A Epstein.

At least 19 recordsLinked to original sources
PubMed1992

Vascular malformation with radiation vasculopathy after treatment of chiasmatic/hypothalamic glioma.

Chiasmatic/hypothalamic gliomas usually are histologically benign astrocytomas that may recur many years after diagnosis and treatment. Three children with chiasmatic/hypothalamic gliomas who were treated at the authors' institution returned 9.5, 11.5, and 2 years, respectively, after radiation therapy (RT) because visual and neurologic deterioration developed. Neuroradiographic studies, including arteriography in two of the patients, showed large mass lesions. These were presumed to be recurrence of tumor, and chemotherapy was administered. Pathologic examination of two children who died and of the third who had a biopsy revealed only a minimal amount of residual, histologically benign astrocytoma, whereas the bulk of the specimen consisted of numerous vessels of variable size. These probably represented incorporation of the rich vasculature in the chiasmal region into the tumor, which underwent degeneration secondary to RT. Radiographic methods did not distinguish progressive tumor growth from the vasculopathy and led to inappropriate clinical diagnoses and treatment.

Adolescent↗
PubMed1992

Cardiac rhythm during temporal lobe seizures.

We studied the neuroanatomic correlates of ictal tachycardia in 27 seizures from five patients with unilateral temporal lobe epilepsy being evaluated with bilateral temporal lobe depth electrodes and orbitofrontal subdural electrodes. There were 11 complex partial seizures, three simple partial seizures, and 13 subclinical seizures. For all seizures, heart rate (HR) increased in a graded fashion as new cortical regions anywhere in the brain were recruited into the seizure. HR plateaued at the new level despite EEG frequency changes until the next region became involved. Increases in HR did not correlate with increased duration of seizures but rather with volume of brain involved. Restricted amygdaloid seizure activity was generally insufficient to alter HR. We conclude that the amygdala has a limited role in modulating HR during seizures, and ictal tachycardia depends principally on the volume of cerebral structures recruited into a seizure.

Adult↗
PubMed1991

Late-onset globoid cell leukodystrophy mimicking an infiltrating glioma.

A 3 1/2 year old girl who developed a gradual left hemiparesis and hemianopia is reported. Neuroimaging studies demonstrated an infiltrating-like high density lesion which crossed the splenium of the corpus callosum, thought to represent a glioma. Subsequent brain biopsy established the correct diagnosis of globoid cell leukodystrophy (GCL), which suggests that the radiographic appearance of late-onset GCL may mimic that of an infiltrating glioma.

Brain↗
PubMed1991

The boundaries of attention deficit disorder.

This report examines distinctions and interrelationships among attention deficit disorder (ADD) and two closely related conditions: learning disability (LD) and oppositional/conduct (O/C) disorder. To evaluate our hypothesis that some of the difficulty in resolving the relationship between ADD and, particularly, O/C may reflect the consequences of selective referral patterns, we studied groups of children diagnosed as ADD from different referral sources. Results suggest that referral bias does exist and that children referred to mental health settings differ from those referred to pediatricians, child neurologists, or psychologists. Because of the nature of the subjects referred to mental health services, nonrepresentative associations may emerge. Rather than being considered as prototypical of all children with attention disorder, children referred to mental health facilities may represent simply an extreme of the continuum of ADD. Evidence suggests that many children with ADD will be represented by those referred primarily for attentional deficits and learning problems, rather than those with inattention, hyperactivity, or aggression referred for child psychiatric evaluation.

Adolescent↗
PubMed1990

The role of plasmapheresis in childhood Guillain-Barré syndrome.

Plasmapheresis has been advocated in the treatment of childhood Guillain-Barré syndrome under the assumption that the results of adult series can be extrapolated to children. To test this assumption, we retrospectively evaluated the medical charts of all children who were admitted to The Children's Hospital of Philadelphia between January 1984 and March 1989, with the diagnosis of Guillain-Barré syndrome. Of the 30 patients identified, 7 were excluded because they had mild disease. Of the remaining 23, 9 underwent plasmapheresis and 14 served as historic control subjects. The two groups were similar with respect to age, presenting symptoms, findings on initial physical examination, and antecedent illnesses at the time of diagnosis. The mean time to recover to Grade 2 (independent ambulation) was significantly shorter in the plasmapheresis-treated group, 24.0 +/- 25.4 days, compared to 60.2 +/- 43.6 days in control subjects (mean +/- 1 SD). Our results indicate that plasmapheresis diminishes morbidity in childhood Guillain-Barré syndrome by shortening the interval until recovery of independent ambulation.

Adolescent↗
PubMed1990

Cavernous angioma presenting as atypical facial and head pain.

Recurrent headache is a common pediatric problem. As the differential diagnosis of headache is extensive, physicians rely on the mode of presentation to focus any investigation. A report of an adolescent in whom atypical facial and head pain caused by a preexisting cerebellar cavernous angioma is presented. Facial pain and headache resolved following excision of the tumor.

Child↗
PubMed1989

Validation of a first-generation Epstein-Barr virus vaccine preparation suitable for human use.

The efficacy of a new vaccine preparation against Epstein-Barr (EB) virus was investigated in cotton-top tamarins. The vaccine consists of fast protein liquid chromatography-purified EB virus membrane antigen glycoprotein of 340 Kd (MA gp340) mixed with a synthetic muramyl dipeptide adjuvant emulsified in squalane containing a pluronic polymer; it is suitable for both scaled-up batch production and eventual administration to man. Vaccinated tamarins rapidly developed ELISA detectable high titre antibodies to MA gp340, and their sera became strongly EB virus-neutralising. After challenge with a massive 100% carcinogenic dose of EB virus, the vaccinated tamarins had a strikingly low level of circulating EB virus-carrying mononuclear cells, in contrast to a control animal, and remained entirely free of tumours. This first-generation vaccine has thus been validated in experimental animals and the way opened for a phase I human trial.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1989

Resonance mode analysis for volume estimation of asymmetric branching structures.

The resonance conditions associated with the propagation of a harmonic wave within a rigid, lossless branching structure can be explicitly derived. In this study, exact resonance conditions are derived for multi-order, rigid, asymmetric branching structures. These are compared with resonance conditions for rigid, multi-order, symmetric branching structures which we reported previously. The effect of asymmetry on the form of the higher-order resonance condition is discussed. In the low-frequency range, the resonance condition can be modified into simpler forms which facilitate volume estimation of the branching structure. Two such volume approximation techniques are presented: (a) a fundamental frequency method, in which the lowest resonance frequency is inversely proportional to the structure volume, and (b) an effective-length method, in which an effective length is calculated for all branches distal to the first bifurcation. Equivalence of the two methods is demonstrated. An experimental study was performed to measure the resonance modes of several second-order glass models with asymmetric branching structures similar to those of mammalian lungs. The resulting volume estimates were in close agreement with the true volumes.

Acoustics↗
PubMed1989

The unsteady form of the Bernoulli equation for estimating pressure drop in the airways.

Previous investigators have used the steady Bernoulli equation to correct the underestimation of alveolar pressure by airway pressure observed during unsteady flow conditions. Using a simple idealized geometry, we demonstrate a method of including the unsteady term of the Bernoulli equation. Our approach was to determine the axial velocity distribution from the wave equation and employ this solution with the unsteady Bernoulli equation. In addition, we estimate the importance of inertia and viscosity and show that these effects can be quantified by the Womersley number.

Air Pressure↗
PubMed1988

Recombinant vaccinia virus expressing Epstein-Barr virus glycoprotein gp340 protects cottontop tamarins against EB virus-induced malignant lymphomas.

A strong association exists between Epstein-Barr (EB) virus and two human cancers, endemic Burkitt's lymphoma and nasopharyngeal carcinoma. In addition, the virus causes infectious mononucleosis [reviewed in Epstein and Achong, 1979, 1986] and more recently has been implicated in lymphomas arising in immunosuppressed individuals [Cleary et al., 1986]. The possibility of preventing or influencing the course of these diseases by vaccination has been advocated for a number of years [Epstein, 1976], especially in the case of undifferentiated nasopharyngeal carcinoma, which is the most common tumour of men in southern China and is prevalent in other specific regions; it therefore represents a major world cancer problem [Shanmugaratnam, 1971]. Two vaccinia virus strains were employed to make recombinants expressing the gene coding for the EB virus envelope glycoprotein, gp340, and were used to vaccinate cottontop tamarins. Protection against EB-virus-induced lymphoma was obtained in animals immunized with the laboratory (WR) strain recombinant but not with those recombinants derived from the vaccine (Wyeth) strain. Circulating antibodies to EB virus gp340 were not detected in any of the immunized animals.

Animals↗
PubMed1988

Effective dead space of differently shaped airways during high-frequency ventilation of a CO2-producing lung model.

A simple lung model is described which simulates the mechanical properties and CO2 production of the lungs of a small animal, and which can be used with high-frequency ventilators. The model was ventilated by a rotary-valve ventilator and the system was used to determine the increment in 'physiological' (Bohr) dead space produced at various ventilatory frequencies between 0.5 and 15 Hz by the insertion of various additional volumes and configurations of 'anatomical' dead space in its 'upper airway'. It was found that the insertion of a straight tube with an internal diameter similar to that of the ventilator outlet tube produced an increment in 'physiological' dead space that remained commensurate with the volume of the added tube at all combinations of the tube volume and ventilatory frequency. The insertion of similar volumes of dead space in the form of tubes with smoothly expanded central portions produced increments in 'physiological' dead space which were commensurate with the volume of the added tube only at the lowest frequencies, and actually became negative at higher frequencies and volumes. These findings provide further evidence that the volume and configuration of the external portion of a high-frequency ventilator system may be of at least as much importance in determining its efficiency as is the lung structure of the animal or patient being ventilated.

Animals↗
PubMed1987

The Florey lecture, 1986. Vaccine prevention of virus-induced human cancers.

Carcinogenic viruses have been discovered in numerous animal species over the last 80 years but their role in human cancer has only recently become an important issue. With EB virus involved with endemic Burkitt's lymphoma and undifferentiated nasopharyngeal carcinoma, hepatitis B virus with primary liver cancer, papilloma viruses with carcinoma of the cervix, and T-cell leukaemia virus with adult T leukaemia, 20-25% of all human cancer appears to have a virus component in its causation. By analogy with certain virus-induced animal cancers, vaccine prevention of infection should greatly reduce subsequent tumour development; vaccines against hepatitis B virus are already on trial for this purpose in populations at risk. Experiments are described in which an EB virus subunit vaccine consisting of the virus-determined membrane antigen glycoprotein molecule of molecular mass 340 kDa (MA gp340) has been prepared by two purification methods. Material from one of these has successfully protected cotton-top tamarins against a 100% lymphomagenic dose of challenge virus and investigations are under way to identify an immunogen, based on MA gp340, suitable for use in man. Genetically engineered bacterial, yeast, and mammalian cells expressing the gp340 gene are already available; this gene has also been inserted into vaccinia and varicella virus vectors. Powerful new adjuvants are also considered, together with future strategies for human vaccine studies.

Animals↗
PubMed1987

Volume estimation of symmetrical branching structures by resonance mode analysis.

An exact resonance condition is derived for rigid symmetric second-order bifurcating structures. In the low-frequency range, the resonance condition can be reduced into forms that facilitate volume estimation of bifurcating structures. Two such volume approximation techniques are presented: (1) a fundamental frequency method, in which the lowest resonant frequency is inversely proportional to the structure volume, and (2) an equivalent-length method, in which an equivalent length of two daughter branches is calculated for all branches distal to the first bifurcation. An experimental study to determine the resonance modes of seven bifurcating glass structures was performed. The volume estimates obtained by either method were in very close agreement with the true volumes.

Animals↗
PubMed1987

Munchausen syndrome by proxy: considerations in diagnosis and confirmation by video surveillance.

Munchausen syndrome by proxy is a form of abuse in which the child suffers from a factitious illness induced by a parent. A case report of an 18-month-old boy who suffered from intractable diarrhea because of the surreptitious administration of laxatives by his mother is presented. The evolution of this case is discussed, as are the legal and ethical considerations in the diagnosis of Munchausen syndrome by proxy.

Child Abuse↗
PubMed1986

Vaccination against Epstein-Barr virus: current progress and future strategies.

A vaccine derived from the high-molecular-weight glycoprotein (gp340) component of the Epstein-Barr (EB) virus membrane antigen conferred complete protection against a 100% lymphomagenic dose of EB virus in the cottontop tamarin, the animal of choice for experiments with EB virus. The membrane-antigen gene has already been cloned, and the development of a vaccine for use in man should now be possible. Such a vaccine could be tested first against infectious mononucleosis, because the effectiveness of vaccination would become evident in a relatively short time. Field trials against Burkitt's lymphoma and nasopharyngeal cancer could follow.

Animals↗