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Biomedical subjects

R Katzman

Publications and source records attributed to R Katzman.

At least 109 records · Page 6Linked to original sources
PubMed1981

Early detection of senile dementia.

Not all senile dementias are irreversible. As this--the first in a series of articles stressing the importance of the early detection of disease states--points out, dementia has been shown to be secondary to treatable disorders in more than 20% of these patients. Investigative efforts, from primary screening to painstaking differential diagnostic approaches, can identify remediable or controllable causes.

Aged↗
PubMed1980

Reduced somatostatin-like immunoreactivity in cerebral cortex from cases of Alzheimer disease and Alzheimer senile dementa.

Both Alzheimer's disease and senile dementia of the Alzheimer type (AD/SDAT) are progressive dementias characterized neuropathologically by the presence in the cerebral cortex of numerous neurofibrillary tangles and neuritic plaques. We use the abbreviation AD/SDAT to denote all such cases, irrespective of age of onset. Studies of neurotransmitter-related parameters in autopsied brain tissues from patients with AD/SDAT have, to date, been confined to five putative transmitter systems. Acetycholine-releasing neurones seem to be most markedly and consistently affected, as judged by the extensive reductions in choline acetyltransferase (ChAT) and acetylcholinesterase activities that have been reported. Despite numerous studies, there is no consistent evidence for the involvement of neurones releasing dopamine, noradrenaline, serotonin, or gamma-aminobutyric acid in AD/SDAT, nor for loss of muscarinic cholinergic receptors. Thus, the involvement of cholinergic neurones in AD/SDAT seems to be specific. However, the possible involvement of neurones using other chemicals as transmitters has yet to be explored. The recent recognition of the existence of so-called 'peptidergic neurones' in the mammalian brain (for review see ref. 8) and the availability of radioimmunoassay (RIA) techniques for studying these peptides, have led us to begin a systematic investigation of neuropeptides in autopsied brain tissue from cases of AD/SDAT, and from neurologically normal individuals. We report here results obtained with a RIA for somatostatin, showing that somatostatin-like immunoreactivity in the cerebral cortex is reduced in tissue from AD/SDAT patients.

Aged↗
PubMed1980

Autoradiographic demonstration of the central origin of regenerating fibers into iris tissue implants in the rat mesencephalon.

One model useful for demonstrating axonal regeneration in the central nervous system is that in which peripheral tissue, particularly the iris, is implanted into the brain or spinal cord. The aim of the present study was to establish the origin of some of the regenerating fibers by the use of an autoradiograhic tracing technique. Briefly, iris implants were inserted in the caudal mesencephalon in the region of the dorsal tegmental bundle in unilaterally sympathectomized rats. Approximately two weeks later, subjects were injected with [3H]leucine in the region of the ipsilateral locus coeruleus and sacrificed two days later. Numerous labeled fibers were observed within the implants and traversing between brain and implant. Fibers formed loose plexuses, coursed along smooth muscle and grew toward blood vessels within the implants. These results may be added to fluorescent histochemical, biochemical and ultrastructural evidence supporting the regenerative capacity of central noradrenergic fibers.

Animals↗
PubMed1980

Pathological verification of ischemic score in differentiation of dementias.

Fourteen case histories of persons who had a histological diagnosis of either senile dementia of the Alzheimer type, multiinfarct dementia, or a mixed dementia composed of these two types and who showed evidence of a moderate to severe dementia on psychological testing were rated for the presence of thirteen clinical features comprising Hachinski's Ischemic Score. These features are frequently considered primarily characteristic of vascular dementia. Persons with senile dementia of the Alzheimer type were clearly differentiable from persons with multiinfarct dementia and mixed dementia, while the latter two groups were indistinguishable from one another. In our sample, eight features were found to characterize those persons with vascular dementia. These data verify the usefulness of the Ischemic Score in differentiating between senile dementia of the Alzheimer type and vascular dementia.

Aged↗
PubMed1980

Treatment of myoclonus with L-5-hydroxytryptophan and carbidopa: clinical, electrophysiological, and biochemical observations.

Six patients with myoclonus of varying cause were treated with L-5-hydroxytryptophan (L-5-HTP) and carbidopa. While spontaneous myoclonus decreased in three of the patients and action myoclonus in four, only two patients had marked functional improvement. Side effects included gastrointestinal and affective disturbances. L-5-HTP therapy caused a diminished frequency of paroxysmal discharges in the electroencephalograms of three patients which did not always correlate with clinical improvement. Lumbar cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA) concentration after probenecid was decreased in all patients prior to therapy, but this reduction did not predict treatment response. Urinary excretion patterns for 5-HTP, serotonin, and 5-HIAA during treatment were similar in responders and nonresponders. It is concluded that while some patients with myoclonus do benefit from L-5-HTP therapy, biochemical and electrophysiological tests are not useful predictors of treatment response, and the high incidence of side effects limits the usefulness of this therapy.

5-Hydroxytryptophan↗
PubMed1980

Selective influence of ergot alkaloids on cortical and striatal dopaminergic and sergotonergic receptors.

The ergot alkaloids studied do exert selective effects on monoamine receptor systems. Lisuride acts as a very potent stimulator of adenylate cyclase in cortical brain regions, and may function as a mixed agonist-antagonist at high concentrations. It is most likely that in cortex, lisuride effects both dopamine and serotonin receptors, but predominantly serotonin receptors coupled to adenylate cyclase. The antagonist molindone exhibits selectivity for cortical serotonin-stimulated cyclase versus dopamine-stimulated cyclase and may prove useful for further elucidating the sites of lisuride action. LSD interacts with serotonin-stimulated cortical adenylate cyclase at higher concentrations than are needed for lisuride stimulation but, nevertheless, at lower concentrations than for serotonin itself (2-4). Bromocriptine, lergotrile and ergonovine may also act as agonists in stimulating adenylate cyclase, but with considerably less potency, and with differences in regional specificity for this stimulation, from lisuride and LSD. Each of these ergots may act as a mixed agonist-antagonist at high concentrations. With respect to the regions studied, antagonist effects on cyclase appear to be more prominent in striatum than in the cortical regions. The greater specificity of lisuride for serotonergic cortical receptors should make this compound useful in further studies of this system.

Adenylyl Cyclases↗
PubMed1979

A direct role of dopamine in the rat subthalamic nucleus and an adjacent intrapeduncular area.

The subthalamic nucleus, a clinically important component of the extrapyramidal motor system, and a lateral area extending into the peduncle contain catecholamine terminals and dopamine receptors coupled to adenylate cyclase. In addition, dopamine agonists administered in vivo enhance glucose utilization in the region. Thus, neuronal function in this region is directly affected by dopamine and dopaminergic drugs.

Adenylyl Cyclases↗
PubMed1978

The cherry-red spot--myoclonus syndrome.

Three young women, 2 of them sisters, were found to have cherry-red spots at the macula when they were children. In 1 patient the spots faded before she was 20 years old. In all 3, incapacitating myoclonus and insidious visual loss developed in adolescence. Their intellect is normal and they have no gargoyle-like features. A variety of lysosomal inclusions were noted in cortical neurons in a biopsy specimen taken from 1 patient in childhood. Liver biopsy fifteen years later revealed mucopolysaccharide-like inclusions in Kupffer cells and hepatocytes. Lipofuscin bodies were abundant in neurons and hepatocytes. The patients excrete sialic acid-containing oligosaccharides not present in normal urine, suggesting a defect in degradation of glycoproteins. The specific enzymatic defect in these patients appears to be a deficiency of lysosomal neuraminidase.

Adolescent↗
PubMed1978

Dementias.

Senile dementia of the Alzheimer type is becoming one of the most common of the malignant diseases as our society ages. Currently, research has identified several pathophysiological changes, including the bihelical filament and the loss of the enzyme choline acetyltransferase from the cortex. Although genetic factors play some role in this disease, the important environmental risk factors have not yet been identified and there is, at present, no specific treatment. The second most common cause of dementia, cerebrovascular disease, produces dementia only when there is destruction of brain tissue, as in individuals who have multiple strokes or who have hypertensive vascular disease leading to multiple lacunae. In both multi-infarct dementia and in the lacunar state, hypertension appears to play a greater role than it does in other forms of vascular disease. Many of the other causes of dementia, including normal pressure hydrocephalus, CNS infections or tumors, metabolic disorders produced by thiamine or vitamin B12 deficiency or thyroid dysfunction, are often reversible. Every patient, whatever the age, with a developing dementia deserves a thorough workup to identify these treatable disorders.

Alzheimer Disease↗
PubMed1977

Reinnervation, myelination and organization of iris tissue implanted into the rat midbrain--an ultrastructural study.

The ultrastructure of autologous irides implanted into the midbrain of mature Sprague-Dawley rats was studied over a time period of 4-14 days. Most features of the normal iris still persisted throughout this time, including typical iris blood vessels and amelanotic melanocytes. At 5-4 days after implantation, the normal innervation of the implanted iris had degenerated, except for the presence of intact Schwann cells and some myelin debris. Reinnervation, beginning about the seventh day, proceeded rapidly. By the fourteenth day, extensive reinnervation of the implant was evidenced by the presence of numerous small (0.1-0.6 micrometer) and large (2-4 micrometer) non-myelinated axons ensheathed in Schwann cell cytoplasm. Axonal varicosities, filled either with dense core or clear core vesicles, formed junctions with axons. These junctions were characterized by an accentuation of areas of the axonal membrane and pre- or post-junctional thickenings; however, we did not observe typical synaptic complexes. Some large axons within the myelinated iris developed thick myelin sheaths of the peripheral nervous system (PNS) type; we believe this is the first reported instance in which myelination of central axons by Schwann cells within the brain parenchyma has been produced by the implantation of PNS elements.

Animals↗