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J Parr

Publications and source records attributed to J Parr.

30 records · Page 2Linked to original sources
PubMed1982

Rat serum stimulates serotonin N-acetyltransferase activity in pineal monolayer cultures.

The effects of rat serum on serotonin N-acetyltransferase (NAT) activity and indole synthesis in monolayer cultures of neonatal rat pineal glands was examined. The addition of 5% rat serum to these cultures resulted in stimulation of NAT activity equal to that obtained with optimal concentrations of the adrenergic agonist norepinephrine (NE). Rat serum also increased the synthesis of both N-acetylserotonin and melatonin from tryptophan. Stimulation of NAT activity by rat serum was partially blocked by metoprolol and propranolol, but not by phentolamine or butoxamine. The serum factor responsible for the stimulation was stable to both freezing and boiling. No significant amounts of epinephrine, norepinephrine, or dopamine were detected in the serum.

Acetyltransferases↗
PubMed1982

Immunocytochemical study of the glial fibrillary acidic protein in human neoplasms of the central nervous system.

The distribution of the glial fibrillary acidic protein (GFAP) was investigated in sections of 131 paraffin-embedded brain neoplasms obtained at surgery or at autopsy. The unlabeled antibody immunoperoxidase (peroxidase-antiperoxidase, PAP) method was used. Equally good results were obtained from 17-year-old material and from recent material derived at surgery or autopsy and fixed with Bouin fluid or phosphate-buffered formalin. The perikaryons and processes of reactive astrocytes showed the most intense stain for GFAP. Positive reaction to antibody against GFAP of varying intensity was demonstrated in astrocytomas of various grades of malignancy (32 of 32), glioblastoma multiforme (10 of 10), subependymal giant cell astrocytoma (1 of 1), ependymoma (2 of 10), subependymoma (4 of 4), and astrocytes in mixed neoplasms (8 of 8). In two neoplasms diagnosed as malignant astrocytomas and in four neoplasms diagnosed as glioblastoma multiforme, GFAP stain was limited to a few neoplastic cells. Usually the stain was more intense over processes than in perikaryons, with the exception of gemistocytic astrocytomas and the giant cells in glioblastoma multiforme, which showed an equally intense stain over perikaryons and processes. The periphery of Rosenthal fibers was intensely positive for GFAP. In astrocytic neoplasms the number of GFAP-positive cells and the intensity of the stain were inversely proportional to the degree of malignancy. In the following neoplasms the reaction for GFAP was negative: oligodendroglioma (3), oligodendroblastoma (1), medulloblastoma (3), medulloepithelioma (1), neuroblastoma (1), pineocytoma (1), typical teratoma of the pineal (1), fibrosarcoma (1), pituitary adenoma (2), craniopharyngioma (1), chordoma (1), chemodectoma of globus jugulare (1), metastatic carcinoma (17), and lymphoma (8). In one of 18 meningiomas, endogenous peroxidase activity was seen in mast cells. All meningiomas studied were negative for GFAP. In one of six neurinomas a positive reaction for GFAP was detected over processes. The authors concluded that the immunostain for GFAP is useful in the diagnoses of astrocytic neoplasms and of mixed gliomas.

Astrocytes↗
PubMed1982

Cerebral dissecting aneurysm and intimal fibroelastic thickening of cerebral arteries. Case report.

A 19-year-old white man developed aphasia and right hemiplegia after several falls while waterskiing. Cerebral angiography displayed a ripple appearance and a "string of beads" sign along the left middle cerebral artery, with occlusion or stenosis of most of its branches. The patient died after 6 days, of transtentorial herniation due to massive left cerebral infarction. At necropsy, the infarct was found to be due to a subintimal dissecting aneurysm of the left middle cerebral artery. Multifocal areas of intimal fibroelastic thickening (IFT) were found not only at the site of dissection, but also in the other cerebral arteries, most prominent at the bifurcations of the vessels. A systematic study of cerebral arteries performed in six control cases revealed that IFT was present in a similar distribution to that seen in the patient described. However, the degree of IFT in this patient was greater than in the controls. Some individuals with excessive IFT may be more susceptible to cerebral dissecting aneurysm under a variety of stresses, especially trauma.

Adult↗
PubMed1981

Morphologic development of neonatal rat pinealocytes in monolayer culture.

The morphological development of pinealocytes maintained in monolayer culture, without the neural and humoral effects present in the developing rat has been studied and compared with the development that occurs in vivo. Pinealocytes in 5 day cultures contained organelles that were similar to those present in the pineals of intact 5 day old rats. However, light and dark cells were not noted in culture, and the cultured cells did not have the dense granules noted in vivo. As pinealocytes developed in culture, cytoplasmic processes increased in length and number. By 21 days of culture age, synaptic ribbons were found to have decreased in number, the difference between light cell and dark cell cytoplasm had become more prominent, and dense-cored vesicles had become more numerous, just as in the developing gland in vivo. These results suggest that the complex neural and humoral factors impinging upon the developing neonatal pineal in the intact animal may not be necessary for some aspects of its ultrastructural differentiation.

Animals↗
PubMed1981

Effects of norepinephrine and dibutyryl adenosine 3',5'-cyclic monophosphate on the ultrastructure of pineal cells in monolayer culture.

To determine how neural influences control the function of the pineal gland, morphological and biochemical relationships after pharmacological treatment have been studied in rat pineal cells in monolayer cultures. Norepinephrine (NE) and dibutyryl cyclic 3',5'-adenosine monophosphate (dBcAMP) treatment of cells that had been in culture for 5 and 21 days produced a stimulation in the enzyme activity of serotonin N-acetyl transferase, an enzyme important in indole synthesis. NE and dBcAMP also produced morphological changes which were dependent on the time of cells in culture. When 5 day-cultures were treated with NE and dBcAMP, light and dark cells were noted and endoplasmic reticulum increased and became more organized. Only dBcAMP treatment at 5 days produced an increase in dense granules and an elongation of cytoplasmic processes. Treatment of 21 day-cultures with dBcAMP also produced an increase in cytoplasmic processes while treatment with NE produced an increase in the synaptic ribbons and clear vesicles within the processes.

Acetyltransferases↗
PubMed1981

Molecular forms of acetylcholinesterase in pineal cell and sympathetic neuronal cultures.

The activities of the various molecular forms of acetylcholinesterase (AChE) were measured in monolayer cultures of neonatal rat pineal cells grown alone and in co-culture with sympathetic neurons. AChE forms characterized by sedimentation coefficients of 4S, 6.5S, and 10S were found in he neuronal and pineal cultures, as well as in the co-cultures. The 16S AChE form was found only in the neuronal cultures. Total AChE activity increased with culture age in the co-cultures, but it decreased in pineal cells cultured alone. The low level of activity present in the neuronal cultures did not change markedly over the 27-day culture period. These results, which show bidirectional neuron-pineal cell effects, suggest that AChE molecular forms may be important markers to study the mechanisms underlying neuron-target cell interaction in the developing sympathetic nervous system.

Acetylcholinesterase↗
PubMed1980

Pineal cells enhance choline acetyltransferase activity in sympathetic neurons.

Cells derived from the neonatal rat pineal gland were cocultured with cells derived from neonatal rat superior cervical ganglia (SCG) in an attempt to determine whether a sympathetic target organ with only adrenergic properties could enhance the development of adrenergic transmitter properties in sympathetic neurons in tissue culture. Choline acetyltransferase was measured as an index of cholinergic differentiation, and tyrosine hydroxylase was measured as an index of adrenergic differentiation. As indices of total cell number and cellular volume, DNA and protein, respectively, were also measured. We found that the pineal-SCG cocultures contained ten times greater choline acetyltransferase activity than sister neuronal cultures cultured without pineal cells, thus indicating that the pineal cells enhanced cholinergic properties in the sympathetic neurons. This cholinergic enhancement was dependent upon the presence of nerve growth factor and could not be obtained with pineal-conditioned medium. Tyrosine hydroxylase activity, measured on cultures sister to those mentioned above, was low in all cultures and decreased somewhat in SCGs cultured alone. TH activity in the pineal-SCG cocultures, however, increased slightly. Some tyrosine hydroxylating activity developed in pineals cultured alone, however, and may have been responsible for the small increase in tyrosine hydroxylase activity noted in the pineal-SCG cocultures. The implications of these results for a determination of the role that target organ plays in the development of the transmitter properties of sympathetic neurons are discussed.

Animals↗
PubMed1979

Cerebellar form of progressive multifocal leukoencephalopathy (PML).

A case of progressive multifocal leukoencephalopathy (PML) with selective involvement of cerebellum and brain stem is compared with nine other published cases. Recognition of PML presenting with ataxia before cerebral manifestations is stressed especially, since promising results with some antiviral drugs have been claimed.

Ataxia↗