PubMed Health⌕ Search

Biomedical subjects

H S Singer

Publications and source records attributed to H S Singer.

At least 37 records · Page 2Linked to original sources
PubMed1987

Inactivation of GM1-ganglioside beta-galactosidase by a specific inhibitor: a model for ganglioside storage disease.

This study was designed to establish an in vitro model with biochemical and morphological similarities to the human neurodegenerative disease GM1 gangliosidosis. Utilizing a specific inactivator of the lysosomal enzyme GM1-ganglioside beta-galactosidase (beta-D-galactopyranosylmethyl-p-nitrophenyltriazene [beta-GalMNT]) and neuroblastoma X glioma hybrid cells (NG108-15), we suppressed beta-galactosidase activity for up to 72 hours. Coincidental with suppression of this enzyme to levels less than 1% of control, we found up to a nine-fold accumulation of its substrate, the GM1-ganglioside, and the ultrastructural appearance of membranous cytoplasmic bodies. beta-GalMNT treatment suppressed growth but had little effect on the specific activity of choline acetyltransferase, lactate dehydrogenase, or other lysosomal enzymes including galactosylceramidase. This model should permit studies of the neurophysiological effects of increased ganglioside accumulation and their reversibility.

Brain↗
PubMed1987

Aminergic systems in Alzheimer's disease and Parkinson's disease.

Biochemical markers for serotoninergic and catecholaminergic neurons in frontal and temporal poles were examined post mortem in brains of patients with Alzheimer's disease, Parkinson's disease, and the two combined. Binding of [3H] citalopram to serotoninergic uptake sites and levels of serotonin were decreased by 40 to 50% in brains of persons in each disease category. In contrast, significant reductions of catecholaminergic markers were not detected. In all three disease groups, the choline acetyltransferase activity was reduced by 50 to 60%. Binding sites for adenosine (A1), muscarinic cholinergic, phencyclidine, beta-adrenergic, and calcium antagonist receptors were unchanged. We conclude that substantial damage to serotoninergic neurons occurs in persons with Parkinson's and Alzheimer's diseases.

Alzheimer Disease↗
PubMed1987

An autoradiographic study of the development of [3H]hemicholinium-3 binding sites in human and baboon basal ganglia: a marker for the sodium-dependent high affinity choline uptake system.

The developmental distribution of the sodium-dependent high affinity choline uptake (SDHACU) system has been studied in the caudate and putamen of the baboon and of the human by in vitro autoradiography with the ligand, [3H]hemicholinium-3 [( 3H]HCh3). Our results show that [3H]HCh3 binding sites in the newborn baboon and fetal human neostriatum are localized to patches, and then adopt a 'striosome-like' distribution in the juvenile baboon brain. These findings indicate a reorganization of [3H]HCh3 binding site distribution during the ontogeny of the primate neostriatum.

Acetylcholinesterase↗
PubMed1987

Neurobehavioral sequelae of minor head injuries in children.

The incidence of neurobehavioral sequelae in children who have sustained minor head injury is controversial. Following an emergency room visit, behavioral symptoms in 247 children with mild head injuries were compared to those in 280 children with trauma to other regions of the body. Serial telephone interviews showed that complaints of irritability, clinging behavior and sleep disturbances were common in both groups, though headaches were a more frequent problem in the head-trauma patients. Virtually all symptoms were transient. Our results demonstrate a high incidence of behavioral sequelae in children after minor head injury and suggest that physicians should counsel parents about this brief functional morbidity.

Adolescent↗
PubMed1987

Saccades in Huntington's disease: initiation defects and distractibility.

We recorded saccadic eye movements in patients mildly affected with Huntington's disease. Most showed an increase in saccade latencies that was greater for saccades made on command than to the sudden appearance of a visual target. All patients showed excessive distractibility during attempted fixation. They had particular difficulty suppressing a saccade to a suddenly appearing visual target when simultaneously trying to initiate a saccade in the opposite direction. Our results are compatible with a posited role of the basal ganglia in both the initiation of volitional saccades and in the maintenance of fixation. Saccade abnormalities--especially distractibility--are sensitive but probably not specific indicators of Huntington's disease.

Adolescent↗
PubMed1987

Reductions in corticotropin releasing factor-like immunoreactivity in cerebral cortex in Alzheimer's disease, Parkinson's disease, and progressive supranuclear palsy.

Dementias occurring in Alzheimer's disease, Parkinson's disease, and progressive supranuclear palsy are associated with dysfunction and death of neurons in a variety of cell populations, including cholinergic, monoaminergic, and peptidergic systems. In the present investigation of these three disorders, we demonstrated decreased levels of corticotropin releasing factor (CRF)-like immunoreactivity in the frontal, temporal, and occipital poles of the neocortex. Moreover, reductions in peptidergic immunoreactivity correlated with reductions in the activity of choline acetyltransferase, the enzyme that catalyzes the formation of acetylcholine. The reduction in cortical CRF levels may be due to abnormalities of intrinsic cortical neurons or to dysfunction in neurons that contain CRF and innervate cortex.

Aged↗
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↗
PubMed1986

Mouse chimeras composed of trisomy 16 and normal (2N) cells: preliminary studies.

Many humans with trisomy 21 (Down Syndrome (DS)) have psychomotor and cognitive retardation, congenital heart disease, and hematologic abnormalities. Partial genetic homology exists between mouse chromosome 16 and human chromosome 21; thus, studies of the development of mice with trisomy 16 (Ts16) may provide important insights into the pathogenesis of these defects and into the mechanisms by which they arise in humans. Since Ts16 mice do not survive the late fetal period, chimeras have been formed between Ts16 and normal (2N) mouse embryos to rescue the Ts16 cells for postnatal studies. In this preliminary study of the postnatal development of such chimeras, we examined the proportion of Ts16 cells in a variety of tissues, including the coat, blood, placenta, heart, and brain. The Ts16 cells made significant contributions to almost all tissues examined. Aspects of the behavior and the neurochemistry of adult Ts16 less than-greater than 2N chimeras were found to differ significantly from control (2N less than-greater than 2N) chimeras and from animals of the two donor embryo strains. Ts16 cells comprised a substantial, but not predominant, proportion of cells in each brain region examined. Suggestions for definitive analyses are reviewed.

Animals↗
PubMed1985

Niemann-Pick disease--type C. Ocular histopathologic and electron microscopic studies.

The presence of lipid storage was demonstrated in type C Niemann-Pick disease by histopathologic and ultrastructural studies. Pleomorphic membranous inclusions, with variable proportions of light and dark granular material, were observed within the conjunctival fibrocytes, endothelial cells and pericytes, keratocytes, lens epithelium, retinal ganglion cells, retinal pigment epithelium, fibrocytes in the uveal tract, and optic nerve fibrous astrocytes. Only optic nerve and retinal ganglion cell involvement had clinical counterparts represented by optic nerve pallor and perimacular gray discoloration.

Child↗
PubMed1985

A therapeutic trial of amniotic epithelial cell implantation in patients with lysosomal storage diseases.

To determine whether allografts of normal amniotic epithelium might provide a nonimmunogenic cellular source of exogenous lysosomal enzymes, subcutaneous implants of amniotic epithelium were performed in six children with clinically advanced storage diseases. The clinical and the biochemical status of each patient was observed for several weeks after amniotic epithelial cell implantation (AECI). Serial studies of blood samples from each patient in the post-AECI period did not demonstrate any increase in levels of deficient lysosomal hydrolase. In two patients, quantitative urinary excretion of substrate was also studied and did not show consistent alterations after AECI. No patient had objective improvement in clinical or neurodevelopmental status following AECI. Two patients died with progressive disease at 2 1/2 and 3 1/2 mo after AECI; no residual amniotic epithelium was found at postmortem examination. Four patients are alive with progressive disease at 6-14 mo after AECI. We conclude that allografts of normal human amnion do not provide sufficient replacement hydrolases for clinical or biochemical improvement in lysosomal storage diseases.

Amidohydrolases↗
PubMed1984

CSF cholinesterase activity in Gilles de la Tourette's syndrome.

Cerebrospinal fluid acetylcholinesterase (AChE) activity was studied as a possible marker for central cholinergic neuronal function in seven patients with Gilles de la Tourette's syndrome. No significant differences were found between CSF AChE activity in untreated or haloperidol-treated patients and control populations. These data do not appear to support a pathophysiologic association between the cholinergic system and Gilles de la Tourette's syndrome.

Adolescent↗
PubMed1984

Cerebrospinal metastases in malignant childhood astrocytomas.

Over a period of five years, antemortem diagnosis of leptomeningeal spread was made in six of thirteen children with high grade astrocytomas. These included four of seven children with hemispheral tumors and two of six children with malignant brainstem gliomas. Leptomeningeal spread was diagnosed by the clinical picture and CSF profile. Meningeal spread occurred an average of 5 months (range 0-16) after initial diagnosis of tumor was made. Several patients responded well to local radiation and/or chemotherapy. Mean survival after evidence of meningeal spread was 7 months (range 2-16) with one patient still alive. Meningeal spread of malignant childhood astrocytomas appears to be common and should be sought for in these patients as local radiation is beneficial. Serious consideration should be given to a controlled trial of prophylactic craniospinal radiation in three tumors. The role of chemotherapy also requires further study.

Adolescent↗
PubMed1984

GM1 gangliosidosis, type 2: ocular clinicopathologic correlation.

The clinical and pathological manifestations of a case of juvenile GM1 gangliosidosis are presented and the pathological findings compared with those previously reported for GM1 gangliosidosis in man and in animal models. The most striking finding in the present case was the marked degeneration of the retinal ganglion cell and nerve fiber layers. Although such extensive ganglion cell loss was not observed in any of the other cases reviewed, the presence of multimembranous inclusion bodies in retinal ganglion cells strongly suggests that the pathological process was similar in all cases. Much remains to be learned about the function of gangliosides in the healthy retina and about the pathophysiological consequences of deranged ganglioside metabolism. The many parallels, including those observed in pathological studies, between the human and animal forms of GM1 gangliosidosis allow an optimistic appraisal of the value of further research using the animal models.

Animals↗
PubMed1984

Morphologic and neurochemical studies of embryonic brain development in murine trisomy 16.

Telencephalic and diencephalic/brainstem regions from embryonic trisomy-16 mice (Ts16) between gestational days 15-18 were analyzed for alterations of morphologic and neurochemical parameters and compared to phenotypically normal littermates. Mean trisomic wet weights from both regions were significantly diminished (greater than 20%) and total protein content was reduced. Ratios of the thickness of the ventricular (germinal) zone to the thickness of the whole cortex were increased, suggesting a delay in neuronal differentiation. Pre- and postsynaptic markers for GABAergic, cholinergic, catecholaminergic and serotonergic transmitter systems were compared. A significant impairment of the trisomic brain catecholaminergic and serotonergic system development was observed, based upon regional reductions in norepinephrine, dopamine and serotonin content. Choline acetyltransferase activity in the diencephalon/brainstem was reduced by 21-26% in contrast to normal levels within the cerebral hemispheres. Presynaptic GABAergic markers were not affected in the Ts16 embryos. It is concluded that although a genetic imbalance involving chromosome 16 in the mouse embryo produces a delay in neurogenesis, it has a more selective effect on the catecholaminergic, serotonergic and cholinergic systems than on GABAergic neurons.

Amino Acids↗
PubMed1984

Synaptic neurochemical alterations associated with neuronal degeneration in an inherited cerebellar ataxia of Gordon Setters.

Canine Inherited Ataxia (CIA) is an autosomal recessive cerebellar disease of Gordon Setters associated with degeneration of Purkinje and granule cells. To define specific biochemical correlates of neuronal loss, synaptic neurochemical parameters were measured in three cerebellar regions (vermis, "pars intermedia," and hemisphere) at early and late stages of this disease. At one and a half years of age, affected dogs showed the most severe lesions in the "pars intermedia," with a 39% decrease in the number of Purkinje cells and a 29% decrease in granule cells. Neurochemical measurements demonstrated decreased [3H]muscimol binding and elevations in norepinephrine concentration (248% above control) and [3H]glutamate receptor binding (118% above control). At five years of age, reduction of Purkinje cells in the three cerebellar regions ranged from 65 to 91% while loss of granule cells was between 13 and 53%. [3H]Muscimol binding remained low throughout the cerebellum (38 to 59% of control) and norepinephrine concentration and [3H]glutamate binding were markedly reduced from the levels observed at one and a half years. Glutamate decarboxylase activity, [3H]QNB binding and GABA concentration were relatively unaffected. Our results indicate that neurochemical parameters associated with cerebellar neuronal systems demonstrate specific alterations in a chronic degenerative disorder. This study also indicates the importance of evaluating neurochemical measurements with regard to both spared and degenerating neuronal systems and emphasizes the role of compensatory neurochemical alterations in cerebellar degenerative disorders.

Animals↗