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Biomedical subjects

D Hoyer

Publications and source records attributed to D Hoyer.

222 records · Page 13Linked to original sources
PubMedDate not supplied

The elusive nature of cerebellar somatostatin receptors: studies in rat, monkey and human cerebellum.

The pharmacological profile and localization of somatostatin (SRIF) receptors were determined in rat, monkey and human cerebellum. In rat cerebellar cortex, low sst1/sst4, intermediate sst2 and very high sst3 receptor mRNA levels were found. sst1 mRNA was also expressed in the deep cerebellar nuclei. [125I]Tyr3-octreotide binding sites in cerebellar membranes correlated with recombinant sst2, but not with sst5 or sst3 receptors and were found in the molecular layer of the cerebellum. [125I]CGP 23996 (in Na(+)-buffer) binding in rat cerebellum correlated with sst1 or sst4, but not with sst2, sst3 or sst5 receptor binding. Similar data were obtained in rhesus monkey cerebellum. mRNAs for all five receptors were found in the granule cell layer of the human cerebellum and/or in the dentate nucleus. [125I]Tyr3-octreotide binding was strong in the molecular layer and correlated with that of recombinant sst2 receptors, but not with sst3 or sst5 receptors. [125I]CGP 23996 (in Mg(++)-buffer) binding was heterogeneous (about 75%, to sst2 and 25% to sst1 and/or sst4 receptors). The molecular and granular layers were equally and the dentate nucleus strongly labeled. Thus, SRIF receptors of the sst2, sst1 and/or sst4 subtype are presnt in the rat, monkey and human cerebellum. In the latter two species, the sst2 type appears to be predominant. Surprisingly, the high expression of sst3 receptor mRNA is not supported by radioligand binding data in any of the species studied. The reason for this discrepancy remains to be elucidated.

Animals↗
PubMedDate not supplied

Nomenclature and classification of transmitter receptors: an integrated approach.

This short assay is an attempt to rationalize an integrated approach to transmitter receptor nomenclature and classification based on three criteria: structural information (gene structure/amino acid sequence), operational 1 information (pharmacological/ ligand-defined/recognitory) and transductional information (receptor-effector coupling) are proposed to be used when considering the naming of existing or newly discovered receptors. It should be recognized that none of these criteria has primacy and that in an ideal situation, as much information as feasible on these three aspects should be collected before the naming of a receptor can be agreed upon.

Animals↗
PubMedDate not supplied

Biocybernetic investigations of pursuit and posture motor control--a strategy for a detailed characterization of movement disorders in brain-damaged children.

By means of a biocybernetic approach the pursuit and posture motor control of brain-damaged children with spastic hemiparesis and disturbed motor coordination of mild extent were investigated. The postural motor control system was loaded by pseudostochastic binary torque sequences applied to the wrist. The dynamics of this system were characterized on the basis of the parameters forearm displacement as well as surface-EMG of M. Biceps and Triceps (calculations of weight functions). The pursuit motor control was analyzed by a pursuit tracking method. By this way the motor capacity for fine and rough motor coordination, motor rhythm, motor adaptation, the maximal speed of movements and motor reaction time could be tested. Considering these results a characterization of movement control on different levels of motor regulation was possible (dynamics of muscular, spinal, and supraspinal components of motor control).

Brain Damage, Chronic↗
PubMedDate not supplied

Serotonin 5-HT3, 5-HT4, and 5-HT-M receptors.

Serotonin (5-hydroxytryptamine [5-HT]) receptors can be classified either pharmacologically, into 5-HT1, 5-HT2, 5-HT3 and 5-HT4 receptors, or functionally, into G-protein-coupled receptors (5-HT1, 5-HT2, and 5-HT4) and ligand-gated ion channels (5-HT3). This article concentrates on the pharmacology, distribution, receptor-effector coupling, possible subtypes, and species differences of 5-HT3 receptors, which are equivalent to Gaddum and Picarelli's 5-HT-M receptor. Also presented here are some of the prominent features of the recently characterized 5-HT4 receptor. Although pharmacologic similarities have been suggested between 5-HT-M and 5-HT4 receptors (some potent 5-HT3 antagonists are active, with lower potency, at 5-HT4 receptors), it is clear that 5-HT4 receptors are different from 5-HT-M receptors.

Animals↗
PubMedDate not supplied

Muscle testing response to provocative vertebral challenge and spinal manipulation: a randomized controlled trial of construct validity.

OBJECTIVE: To evaluate the relationship of muscle strength response to a provocative vertebral challenge and to spinal manipulation. DESIGN: Prospective double-blind randomized controlled trial: crossover and between subjects designs. SETTING: Laboratory: Center for Technique Research. PARTICIPANTS: Sixty-eight naive volunteers from the student body, staff and faculty of the college. INTERVENTIONS: Provocative vertebral challenge: standardized 4-5 kg force applied with a pressure algometer to the lateral aspects of the T3-12 spinous processes. INTERVENTION: manual high velocity low amplitude adjustment or switched-off activator sham. MAIN OUTCOME MEASURES: Piriformis muscle response was defined in two ways: reactivity (a decrease in muscle resistance, yes or nor, following a vertebral challenge); responsiveness (the cessation of reactivity following spinal manipulation). Relative response attributable to the maneuver (RRAM): the percent of an outcome attributable to the challenge or adjustment itself. RESULTS: Average RRAM = 16% reactivity to vertebral challenge; average RRAM = 0% responsiveness to spinal manipulation. Six to 10% of muscle tests were positive regardless of examiner, previous finding or intervention. CONCLUSIONS: For the population under investigation, muscle response appeared to be a random phenomenon unrelated to manipulable subluxation. In and of itself, muscle testing appears to be of questionable use for spinal screening and post-adjustive evaluation. Further research is indicated in more symptomatic populations, different regions of the spine, and using different indicator muscles.

Adult↗