PubMed Health⌕ Search

Biomedical subjects

R Noble

Publications and source records attributed to R Noble.

53 records · Page 3Linked to original sources
PubMed1982

Connexions between hair follicle afferent fibres and spinocervical tract neurones in the cat: the synthesis of receptive fields.

1. Relationships between the terminal arborizations of hair follicle afferent fibres and dendritic trees of spinocervical tract (s.c.t.) neurones were studied using intra-axonal and intracellular injections of horseradish peroxidase in chloralose-anaesthetized, paralysed cats. 2. Seventeen afferent-neurone pairs were successfully stained and their receptive fields determined. Ten of the pairs had s.c.t. neurones with a field containing that of the hair follicle afferent and seven pairs had separate fields on the hind limb. 3. Where the afferent fibre's field was outside the neurone's field there were no indications of synaptic contacts between the two neuronal elements. 4. Synaptic contacts were always observed (at the light microscope level) for the ten pairs with the hair afferent's receptive field contained within the s.c.t. cell's field. Contacts were always made by the branches of only a single collateral from the hair follicle afferent fibre. The numbers and locations of synaptic contacts were related to the relative positions of the receptive field: where the hair follicle afferent's field was centrally placed there were many (forty to sixty) contacts on proximal dendrites; where the hair follicle afferent's field was peripherally placed in the s.c.t. cell's receptive field there were few contacts (two to thirteen) and these were peripherally placed on the dendritic tree. Where the primary afferent fibre had a centrally placed field contacts upon dendritic spines were observed. 5. The results are discussed in terms of the synthesis of receptive fields and the organization of neuronal connexions within the mammalian spinal cord.

Afferent Pathways↗
PubMed1980

The density, distribution and topographical organization of spinocervical tract neurones in the cat.

1. In acute experiments, detailed grids of micro-electrode recordings were made from spinocervical tract (s.c.t.) cells in the lumbosacral cord of anaesthetized cats. These grids provided electrophysiological data on the location, distribution, density and somatotopic organization of s.c.t. neurones.2. In acute experiments lasting up to 48 hr, retrograde labelling of s.c.t. cells was carried out by injecting horseradish peroxidase into the lateral cervical nucleus in anaesthetized cats. The aim was to flood the nucleus with the enzyme so that all s.c.t. neurones would be labelled in order to provide an independent check on the location, density and distribution data obtained in the electrophysiological experiments.3. The electrophysiological and the anatomical experiments were sometimes performed on the same animal.4. The electrophysiological and anatomical results were in excellent agreement. (a) S.c.t. cells are located mainly in ipsilateral laminae III, IV and V. About 25% are in lamina III, 60% in lamina IV and 10% in lamina V. There are a few cells in laminae I, II and VI making up the remaining 5%. (b) There are about 550-800 s.c.t. cells in the lumbosacral enlargement (L4-S2 inclusive) on each side of the cord. Most cells are in L7-S1 where there are twenty to forty s.c.t. neurones in each millimetre length of cord.5. Many marginal (lamina I) cells were labelled with the retrograde horseradish peroxidase method and a few cells on the contralateral side in laminae III-V and VII-VIII were also labelled. The marginal cells formed 12-18% of labelled cells on the side of injection and, in addition, a similar absolute number of marginal cells was labelled on the side contralateral to the injection. The possible identity of these neurones is discussed.6. S.c.t. cells form a sheet of neurones across the dorsal horn. The sheet is organized somatotopically in a way which resembles the representation of the hind limb dermatomes in the dorsal columns (Werner & Whitsel, 1967). There is a relative enlargement of the L6-S1 dermatomes which encroach upon their neighbouring cord segments. The gradient of the map is very steep in the mediolateral direction but gradual in the rostrocaudal direction. The detailed somatotopic maps generated in the present work have revealed that s.c.t. cells are arranged so that their receptive fields form longitudinal columns and cells within the columns have overlapping fields.

Animals↗
PubMed1980

Projections from Pacinian corpuscles and rapidly adapting mechanoreceptors of glabrous skin to the cat's spinal cord.

1. Single axons innervating Pacinian corpuscles and rapidly adapting mechanoreceptors of the foot and toe pads were injected with horseradish peroxidase near their entrance to the lumbosacral spinal cord in cats anaesthetized with chloralose and paralysed with gallamine triethiodide. Subsequent histochemistry revealed the morphology of the intra-spinal parts of the axons. 2. All Pacinian corpuscle axons that could be traced into the dorsal root bifurcated upon entering the cord into ascending and descending branches. All Pacinian corpuscle axons gave rise to collaterals that entered the dorsal horn. 3. The collaterals of Pacinian corpuscle afferent fibres had a distinctive morphology. They provided two regions of termination, a larger dorsal region in laminae III and IV and a smaller ventral region in laminae V and VI. Within the dorsal region the terminal axons ran mainly in the longitudinal axis of the cord and carried many boutons en passant. Within the ventral region the axons ran dorso-ventrally in the transverse plane of the cord and although carrying some boutons en passant also gave rise to clusters of boutons. 4. The collaterals of rapidly adapting afferent fibres had a distinctive morphology different from that of the Pacinian corpuscle afferent fibre collaterals. The termination region of rapidly adapting afferents was limited almost exclusively to lamina III, with only slight extension into lamina IV. Boutons were mainly of the en passant type and terminal axons were generally orientated within the longitudinal axis of the cord. 5. The morphology of the afferent fibre collaterals is discussed in relation to the physiology of the dorsal horn.

Animals↗
PubMedDate not supplied

Factors affecting alkalinity generation by successive alkalinity-producing systems: regression analysis.

Use of successive alkalinity-producing systems (SAPS) for treatment of acidic mine drainage (AMD) has grown in recent years. However, inconsistent performance has hampered widespread acceptance of this technology. This research was conducted to determine the influence of system design and influent AMD chemistry on net alkalinity generation by SAPS. Monthly observations were obtained from eight SAPS cells in southern West Virginia and southwestern Virginia. Analysis of these data revealed strong, positive correlations between net alkalinity generation and three variables: the natural log of limestone residence time, influent dissolved Fe concentration, and influent non-Mn acidity. A statistical model was constructed to describe SAPS performance. Subsequent analysis of data obtained from five systems in western Pennsylvania (calibration data set) was used to reevaluate the model form, and the statistical model was adjusted using the combined data sets. Limestone residence time exhibited a strong, positive logarithmic correlation with net alkalinity generation, indicating net alkalinity generation occurs most rapidly within the first few hours of AMD-limestone contact and additional residence time yields diminishing gains in treatment. Influent Fe and non-Mn acidity concentrations both show strong positive linear relationships with net alkalinity generation, reflecting the increased solubility of limestone under acidic conditions. These relationships were present in the original and the calibration data sets, separately, and in the statistical model derived from the combined data set. In the combined data set, these three factors accounted for 68% of the variability in SAPS systems performance.

Calibration↗
PubMedDate not supplied

Olfactory response to mushroom composting emissions as a function of chemical concentration.

Odor pollution is a major problem facing mushroom [Agaricus bisporus (Lange) Imbach] compost production. Techniques for quantifying mushroom composting odors are needed to assess the effectiveness of odor control measures. Odor samples were obtained in nalophane bags from 11 mushroom composting sites. Samples were collected 0.2 m downwind from the pre-wetting heaps (aerated or unaerated) of raw composting ingredients (wheat straw, poultry and horse manures, and gypsum) and subsequent Phase I composting windrows or aerated tunnels. The odor concentrations (OCs) of the samples were assessed using serial dilution olfactometry and the chemical composition of the samples was determined using gas chromatography-mass spectrometry (GC-MS), both 24 h after sampling. Gas detector tubes were used for on-site measurement of gaseous compounds. Odorants that exceeded their published olfactory detection thresholds by the greatest order of magnitude, in decreasing order, were: H2S, dimethyl sulfide (DMS), butanoic acid, methanethiol, and trimethylamine. Concentrations of NH3 were not significantly correlated with OC, and they were not significantly affected by the use of aeration. Aeration reduced the OC and the combined H2S + DMS concentrations by 87 and 92%, respectively. There was a very close correlation (r = 0.948, P < 0.001) between the OC of bag samples and the combined H2S + DMS concentrations, measured on-site with detector tubes. This relationship was unaffected by the NH3 concentration or the type of compost: aerated or unaerated, pre-wet or Phase I, poultry manure-based or horse and poultry manure-based compost. Prediction of the OC will enable rapid and low-cost identification of odor sources on mushroom composting sites.

Agaricales↗