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Biomedical subjects

J Buchhalter

Publications and source records attributed to J Buchhalter.

9 recordsLinked to original sources
PubMed2001

Delayed diagnosis of pediatric Langerhans' cell histiocytosis: case report and retrospective review of pediatric cases seen at Mayo Clinic.

Langerhans' cell histiocytosis is a disease of the dendritic histiocytes with a wide variety of clinical manifestations. This report describes a boy with Langerhans' cell histiocytosis who presented with primarily neurologic and endocrinologic findings, without pain. The diagnosis of Langerhans' cell histiocytosis was not made until 10 years after symptom onset. The pathology database at Mayo Clinic was searched for cases of Langerhans' cell histiocytosis between 1985 and 1999 under 19 years of age (65 children), and information regarding clinical presentation was abstracted. Database review found a range of 1 day to 156 weeks (mean 13.8 weeks) from symptom onset to diagnosis. No other patients with primarily neurologic symptoms were found. The diagnosis of Langerhans' cell histiocytosis was made significantly sooner after onset if pain was present (chi-square = 19.1, P < .001, two-tailed, phi coefficient 0.54). Our findings indicate that neurologic manifestations of Langerhans' cell histiocytosis are rare, and the combination of diabetes insipidus, ataxia, skin rash, or osseous pain should alert the clinician to the possibility of Langerhans' cell histiocytosis and avoid delayed diagnosis.

Adolescent↗
PubMed1998

Incidence of spikes and paroxysmal rhythmic events in overnight ambulatory computer-assisted EEGs of normal subjects: a multicenter study.

The incidences of spikes and paroxysmal rhythmic events (PREs) in 10-h overnight EEGs of normal adult volunteers (n=135) were studied at 11 sites with a computer-assisted ambulatory EEG monitoring system with automatic spike and PRE detection. Spikes were evident in the overnight EEG of 1 subject (0.7%), and PREs were apparent in the overnight EEG of the same subject (0.7%). The incidences of spikes of 24 other subjects with a history of migraine and/or a family history of epilepsy were 12.5 and 13.3%, respectively. The overnight EEGs of these subjects were significantly more likely to show spikes than the overnight EEGs of subjects without migraine or a family history of epilepsy.

Adolescent↗
PubMed1994

Properties of inhibitory and excitatory synapses between hippocampal neurons in very low density cultures.

The whole cell patch clamp technique was used to examine the electrophysiological properties of embryonic hippocampal neurons maintained in a very low density (VLD) culture preparation. The goal of these experiments was to establish the viability of the VLD culture as a model system in which to study regulation of neurotransmission at single monosynaptic connections, in the absence of polysynaptic innervation. Depolarization of neurons in the VLD culture revealed voltage-dependent sodium, calcium, and potassium currents which were blocked with, respectively, tetrodotoxin (TTX), cobalt, and tetraethylammonium and 4-aminopyridine. When pairs of neurons were simultaneously recorded, action potentials evoked in presynaptic neurons elicited either excitatory or inhibitory postsynaptic currents (EPSCs or IPSCs, respectively). The dual component EPSCs were due to the activation of both types of postsynaptic, ionotropic glutamate receptors: N-methyl-D-aspartate (NMDA) and non-NMDA receptors. Evoked IPSCs were due to the activation of postsynaptic gamma-aminobutyric acid (GABA) receptors. Both excitatory and inhibitory synapses exhibited short term depression in response to high frequency stimulation, although IPSCs were routinely decreased to a much greater degree than EPSCs. Spontaneous miniature EPSCs and IPSCs were found to persist in TTX, were blocked by the same pharmacological antagonists which blocked evoked responses, increased in frequency in response to hypersomotic solution, and were unaffected by changes in extracellular calcium concentration. mIPSCS were found to occur at a significantly lower frequency than mEPSCs. These experiments indicated that neurotransmission in the VLD cultures occurs in a manner consistent with the quantal hypothesis and, therefore, the VLD culture is a good model for studying excitatory and inhibitory neurotransmission between isolated pairs of neurons. In addition, these experiments, performed under comparable physiological conditions, demonstrated that there are fundamental differences underlying neurotransmitter release between excitatory and inhibitory neurons.

Animals↗
PubMed1993

HIV-1 Tat alters normal organization of neurons and astrocytes in primary rodent brain cell cultures: RGD sequence dependence.

The HIV-1 trans-activator protein Tat has been implicated as a mediator of neuronal dysfunction in several model systems. To explore the possibility that Tat can affect primary brain cells, we examined the effect of recombinant Tat protein on rat cortical brain cell cultures. Tat induced marked aggregation of neurons and astrocytes in developing cultures and caused the neuritic processes to coalesce into fascicles. Cell death was not seen and brain macrophages were not affected. These effects mapped to a different region from the trans-activation domain of Tat, as mutating the RGD (arginine-glycine-aspartic acid) sequence within the second exon abrogated aggregation and fascicle formation without affecting trans-activation capacity. Such effects on primary neurons and astrocytes may reflect specific interactions of Tat with uninfected cells within the CNS in vivo.

Amino Acid Sequence↗
PubMed1990

Double-stranded RNA unwinding and modifying activity is detected ubiquitously in primary tissues and cell lines.

A double-stranded RNA unwinding and modifying activity was found to be present in a wide range of tissues and cell types. The level of activity did not vary significantly with respect to the state of cell differentiation, cell cycle, or transformation. Thus, the unwinding and modifying activity, localized in the nucleus in somatic cells and capable of converting many adenosine residues to inosine, appears to be one of the housekeeping genes.

Animals↗
PubMed1988

Sciatic neuropathies in childhood: a report of ten cases and review of the literature.

Primary lesions affecting the sciatic nerve are uncommon, especially in children. Isolated sciatic nerve involvement was found in ten patients during an 8 1/2-year period at a metropolitan children's hospital. Etiologic mechanisms included three with compression and one each with stretch injury after operation using the lithotomy position, stretch injury after closed reduction of hip dislocation, puncture wound, lymphoma, hypersensitivity vasculitis associated with hypereosinophilia, indeterminate lesion associated with transverse myelitis, and idiopathic progressive lesion with negative findings on exploration. Neonatal injuries associated with breech delivery or intragluteal injections were not causative factors in this series. Children with sciatic neuropathies have a variable prognosis depending on the etiology. Compression was the only potentially preventable pathophysiologic mechanism.

Adolescent↗
PubMedDate not supplied

Expression of somatostatin and GABA immunoreactivity in cultures of rat hippocampus.

Somatostatin (SOM) synthesis and release were studied with radioimmunoassay and immunocytochemical techniques in rat fetal hippocampal neurons maintained in monolayer tissue culture. SOM immunoreactivity increased from undetectable to over 4,000 pg/ml in media and over 2,500 pg/culture in neurons by 3 to 5 weeks. After 3 weeks, approximately 11% of the neurons stained for SOM. Gamma-aminobutyric (GABA) immunoreactivity was present in hippocampal neurons from 1 day to 5 weeks with 40-50% of the neurons staining for GABA by 5 weeks in vitro. Costaining neurons for SOM and GABA revealed that 63% which were positive for SOM also stained for GABA.

Animals↗