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Biomedical subjects

R Porter

Publications and source records attributed to R Porter.

At least 235 records · Page 13Linked to original sources
PubMed1967

The synaptic basis of a bilateral lingual-hypoglossal reflex in cats.

1. Reflex discharge of some hypoglossal neurones innervating the intrinsic musculature of the tongue occurred following single stimuli delivered to low threshold afferents in the ipsilateral or contralateral lingual nerves of decerebrate cats.2. The discharge produced by contralateral lingual nerve stimuli was smaller and had a longer latency than that produced by ipsilateral lingual nerve stimuli. The timing of the ipsilateral response suggested that two synapses were included in the reflex arc.3. Intracellular recordings in hypoglossal motoneurones revealed complex depolarizing and later hyperpolarizing synaptic respones following single nerve stimuli. The direction of the early synaptic action in any cell was the same whether low threshold afferents in the ipsilateral or the contralateral lingual nerve were stimulated. The timing of these synaptic responses and the occurrence of ripples on the rising phase of many of the depolarizing potentials was consistent with the presence of an internuncial neurone in the pathway from the afferent fibres to the motoneurone.4. Recordings were made of the discharges of neurones in or near the sensory nucleus of the spinal trigeminal tract caused by lingual nerve stimuli. The latencies of these discharges and the characters of the bursts of responses which followed single lingual nerve stimuli indicated that these neurones could be the internuncials on the reflex pathway.5. The relationship of these findings to the observations of Miller & Sherrington (1915) on the ;licking' reflex is discussed.

Animals↗
PubMed1967

Cortical actions on hypoglossal motoneurones in cats: a proposed role for a common internuncial cell.

1. Intracellular records were made of the synaptic potentials produced in hypoglossal motoneurones when electrical stimuli were applied to the cat's motor cortex.2. The depolarizing synaptic responses reached their maxima in steps similar to those produced in the same motoneurones by suprathreshold stimulation of the lingual nerve.3. Interneurones in or near the spinal trigeminal nucleus were caused to discharge by cortical shocks adequate to produce synaptic potentials in hypoglossal motoneurones. The latencies and patterns of repetitive responses in these interneurones were consistent with their possible role as internuncial cells in the motor pathway from cerebral cortex to hypoglossal motoneurones.4. Individual interneurones in or near the spinal trigeminal nucleus could be caused to discharge both by stimulation of the lingual nerve and by stimulation of the motor cortex. This convergence suggests a common function for the internuncial cell in reflexly and cortically induced excitation of hypoglossal motoneurones and would allow the internuncial cell to be a site for integration of spatially separated excitatory influences.

Animals↗
PubMed1966

Lingual mechanoreceptors activated by muscle twitch.

1. Two groups of mechanoreceptors in the tongue have been identified by recording afferent discharges in single nerve fibres dissected from the lingual nerves of anaesthetized cats. The group of superficially situated, rapidly adapting mechanoreceptors had faster conduction velocities than the presumed deeply situated, slowly adapting endings.2. Stretch of the tongue musculature did not prove to be as efficient in activating the endings as local deformation, although it was possible to excite some of the presumed deeply situated endings in this way.3. No mechanoreceptor fibres could be identified in filaments dissected from the hypoglossal nerves in the same experiments.4. Twitches of the tongue musculature produced by stimulation of the hypoglossal nerve were able to cause discharge of superficial and presumed deeply situated mechanoreceptors during the tension change.5. The timing of the discharges in response to twitch was such that it could account for the delay in synaptic potentials produced in hypoglossal motoneurones when supramaximal stimuli were applied to the hypoglossal nerve.6. The possible significance of mechanoreceptor discharges in reflex activation of tongue motor units is discussed.

Animals↗
PubMedDate not supplied

Employee motivation: new perspectives of the age-old challenge of work motivation.

In this qualitative study, the 1950s-1970s work of Frederick Herzberg, the father of work motivational research, was compared, and contrasted with current data study about management effectiveness to explore how employee motivation may have changed. Staff members and managers (N = 38), primarily from healthcare settings, but also from academic, public, and private sector businesses were interviewed. Interpersonal relations now ranks first as a motivating factor in this study. Recognition, the work itself, and responsibility are still ranked as critical motivating factors. These are important to understand as work is redesigned. Supporting positive interpersonal relations among subordinates, supervisors, and peers can be viewed as an effective management strategy to facilitate employee motivation. For employees, developing positive interpersonal relations with co-workers can enhance individual motivation and may improve job satisfaction.

Adult↗
PubMedDate not supplied

Climatic and environmental patterns associated with hantavirus pulmonary syndrome, Four Corners region, United States.

To investigate climatic, spatial, temporal, and environmental patterns associated with hantavirus pulmonary syndrome (HPS) cases in the Four Corners region, we collected exposure site data for HPS cases that occurred in 1993 to 1995. Cases clustered seasonally and temporally by biome type and geographic location, and exposure sites were most often found in pinyon-juniper woodlands, grasslands, and Great Basin desert scrub lands, at elevations of 1,800 m to 2,500 m. Environmental factors (e.g., the dramatic increase in precipitation associated with the 1992 to 1993 El Niño) may indirectly increase the risk for Sin Nombre virus exposure and therefore may be of value in designing disease prevention campaigns.

Animals↗
PubMedDate not supplied

Prevalence, incidence, management, and predictors of venous ulcers in the long-term-care population using the MDS.

OBJECTIVE: To describe the prevalence, incidence, management, and predictors of venous ulcers in residents of certified long-term-care facilities using the Minimum Data Set. DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: 32,221 residents admitted to long-term-care facilities in Missouri between January 1, 1996, and October 30, 1998. MAIN OUTCOME MEASURES: Version 2.0 of the Minimum Data Set was utilized. Assessment items included selected measures from background information, disease diagnoses, physical functioning and structural problems, health conditions, oral/nutritional status, and skin condition. MAIN RESULTS: Venous ulcer prevalence on admission was 2.5%. The incidence of venous ulcer development for long-term-care residents admitted without an ulcer at 90, 180, 270, and 365 days after admission was 1.0%, 1.3%, 1.8%, and 2.2%, respectively. The most frequent skin treatments for residents with a venous ulcer were ulcer care, dressings, and ointments. Factors associated with venous ulcer development within a year of admission were diabetes mellitus, peripheral vascular disease, and edema. CONCLUSION: Venous ulcer prevalence and incidence are greater in the long-term-care population than in the community at-large. Residents with a venous ulcer are likely to have comorbid conditions such as diabetes mellitus, peripheral vascular disease, congestive heart failure, edema, wound infection, and pain. Based on these data, risk factors such as history of leg ulcers, recent edema, diabetes mellitus, congestive heart failure, or peripheral vascular disease should prompt clinicians to carefully plan care that will manage a resident's risk for venous ulcer development.

Activities of Daily Living↗
PubMedDate not supplied

Happy hedonists.

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Europe↗