Search PubMed⌕ Search

Biomedical subjects

S F Atweh

Publications and source records attributed to S F Atweh.

47 records · Page 3Linked to original sources
PubMed1984

Modulation of segmental mechanisms by activation of a dorsal column brainstem spinal loop.

In decerebrate-decerebellate cats, dorsal column stimulation (DCst) rostral to selective dorsal funicular cuts, to prevent antidromic activation of afferent DC fibers, produced primary afferent depolarization and modulated reflexes at the lower spinal level. These findings indicate the importance of a DC-brainstem-spinal loop in explaining the effects of DC stimulation in man and experimental animals.

Animals↗
PubMed1984

Response of C-6 glioma to isoproterenol and papaverine in vivo depends on beta-adrenergic receptor density.

Rat C-6 glioma serves as an experimental model for human glioma. C-6 glioma cells carried to high culture passages in medium containing 10% fetal bovine serum when injected in vivo are unresponsive to treatment with the beta-adrenergic agonist isoproterenol and the phosphodiesterase inhibitor papaverine. When C-6 glioma cells are kept in culture in serum-containing medium, beta-adrenergic receptor density falls and, concomitantly, ability to accumulate cyclic adenosine monophosphate in response to stimulation with catecholamines declines. Responsiveness to treatment in vivo with a beta-adrenergic agonist was restored when C-6 glioma cells were cultured in serum-free defined medium prior to systemic injection into rats. Culturing of C-6 glioma cells in serum-free medium significantly increases the number of beta-adrenergic receptors when compared with C-6 glioma cells grown in serum-containing medium.

Animals↗
PubMed1983

Monoclonal antibodies to choline acetyltransferase: production, specificity, and immunohistochemistry.

Immunohistochemical localization of choline acetyltransferase (ChAT) in cholinergic neurons has been difficult to achieve because of problems encountered in producing specific antisera. Here we describe the production and characterization of several distinct monoclonal antibodies to ChAT. Each of the monoclonal antibodies exhibits one of three general patterns of cross-species reactions; one pattern shows reactivity limited mainly to bovine ChAT, a second pattern shows reactivity only to ChAT from higher mammals including humans, and the third pattern shows reactivity to ChAT from all mammals tested. The antibodies bound specifically to two closely related bovine proteins of 68,000 and 70,000 daltons using the Western blotting technique. One of the antibodies was used to localize immunohistochemically known cholinergic structures in the rat brain, including motor neurons, basal forebrain neurons, and neostriatal neurons.

Animals↗
PubMed1977

Autoradiographic localization of opiate receptors in rat brain. III. The telencephalon.

Opiate receptor distribution, determined by the autoradiographic localization of stereospecific [3H]diprenorphine binding sites, was examined in the telencephalon. Areas showing very dense or dense localization of receptors included parts of the presubiculum and amygdala, patchy areas in the caudate-putamen and accumbens, the subfornical organ, the interstriatal nucleus of the striae terminalis and the anterior olfactory nucleus, pars externa. Lower densities were found in other parts of the hippocampal formation, the deeper part of the cerebral cortex, the entopeduncular nucleus, globus pallidus, nucleus triangularis septi and nucleus paratenialis. The significance of these findings is discussed in terms of the biochemical and physiological actions of opiates.

Amygdala↗
PubMed1977

Autoradiographic localization of opiate receptors in rat brain. II. The brain stem.

The distribution of opiate receptors, determined by the autoradiographic localization of stereospecific [3H]diprenorphine binding sites, was studied in the brain stem. Areas showing very dense or dense localizations of receptors included the parabrachial nuclei, the superior colliculus, the ventral median raphe nucleus, components of the accessory optic system, portions of the habenulo-interpeduncular complex, the pretectal nuclei and the ventral lateral geniculate, the infundibulum and the medial thalamus. Moderate grain densities were found in broad areas of the upper medulla, midbrain and diencephalon. The significance of these findings are discussed in terms of pain mechanisms, association of some receptors with small diameter axons, pupillary reflexes, hormonal control, and effects of opiates on neurotransmitter systems.

Animals↗
PubMed1977

Autoradiographic localization of opiate receptors in rat brain. I. Spinal cord and lower medulla.

The localization of opiate receptors in the spinal cord and lower medulla has been elucidated by the autoradiographic identification of stereospecific [3H]diprenorphine (a potent opiate antagonist) binding sites. The opiate receptors were higly localized to: layers I (marginal cell zones) and II (substantia gelatinosa) of the dorsal horn of the spinal cord; the substantia gelationsa of the spinal trigeminal nucleus; components of the vagal system, including the vagus nerve, nucleus tractus solitarius, nucleus commissuralis, nucleus intercalatus, nucleus ambiguus and nucleus originis dorsalis vagus; the area postrema. Examination of [3H]etorphine (a potent opiate agonist) binding sites showed the same distribution. We conclude that, in these brain regions, opiate receptors are (1) highly associated with areas receiving small, afferent primary fibers, (2) strategically placed to modulate noxious stimuli as well as explain some visceral side effects of opiate administration.

Afferent Pathways↗
PubMed1976

Effects of anesthetics and septal lesions and stimulation on 3H-acetylcholine formation in rat hippocampus.

The rate of 3H-acetylcholine (ACh) formation from i.v. injected 3H-choline was studied in the rat hippocampus after various treatments which alter the activity of cholinergic septal hippocampal neurons. Administration of pentobarbital and placement of acute septal lesion reduced the formation of 3H-ACh but did not change 3H-choline content. Chloral hydrate administration reduced the formation of 3H-ACh and also increased 3H-choline content. The chloral hydrate induced increase in 3H-choline occurred also in animals with chronic septal lesions. Electrical stimulation of the septum caused an increase in both 3H-ACh and 3/-choline. Chronic septal lesion caused a reduction in both radioactive and endogenous ACh, but did not affect radioactive or endogenous choline. These findings suggest that there are multiple pools of choline in the brain and that the precursor pool for ACh synthesis is difficult to measure. Overall, the parameter that best correlated with cholinergic activity was the level of 3H-ACh. Possible mechanisms, for this finding are discussed.

Acetylcholine↗
PubMed1974

Polysensory interactions in the cuneate nucleus.

1. The effects of light flashes or sound clicks on somatic sensory activity in the cuneate nucleus of the cat were studied. Polysensory interactions were demonstrated by means of gross potential recording in the cuneate nucleus or medial lemniscus, single unit recording in the cuneate nucleus, and excitability testing of tract terminals.2. Brief flashes or clicks were found to produce negative (N) and positive (P) waves in the cuneate nucleus similar to those produced by cutaneous stimulation. Furthermore, the P wave evoked by conditioning photic or acoustic stimuli depressed the P wave produced by cutaneous test stimuli.3. Conditioning photic or acoustic stimuli inhibited spontaneously firing cuneate neurones as well as those driven by cutaneous test stimuli.4. Conditioning photic or acoustic stimuli depressed the test discharge in the medial lemniscus evoked by cutaneous test stimuli.5. Micro-electrode stimulation within the cuneate nucleus evoked an antidromic response in the superficial radial nerve consisting of two spike complexes. Conditioning photic or acoustic stimuli caused an increase in the size of the initial spike complex and a depression in the secondary spike complex. These changes and the time courses of all the interactions observed were suggestive of presynaptic inhibition.6. The modulatory influences of photic and acoustic stimuli on the cuneate nucleus were present under alpha-chloralose or pentobarbitone anaesthesia and the acoustic influence persisted after midcollicular decerebration. When added to other evidence, the above findings suggest that the reticular formation of the brain stem plays an important role in these polysensory interactions.

Acoustic Stimulation↗
PubMed1971

Visual and auditory inputs into the cuneate nucleus.

Sound clicks or light flashes modify somatic sensory activity in the cuneate nucleus of the cat. The techniques of gross potential recording in the cuneate nucleus or medial lemniscal tract, of single unit recording in the cuneate nucleus, and of excitability testing of cuneate terminals demonstrate this heterosensory interactionsensory interaction.

Acoustic Stimulation↗