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Biomedical subjects

G Grant

Publications and source records attributed to G Grant.

At least 217 records · Page 12Linked to original sources
PubMed1984

Solitary silent venous papillary loops and ocular hypertension.

A series of 24 eyes in 23 patients is described showing solitary silent venous papillary loops. These loops are usually associated with a considerable degree of ocular hypertension, presenting when this hypertension is being investigated. They are silent, usually with no previous ocular history, single with a large diameter, affecting veins at the optic disc and not extending into the vitreous. The optic disc is cupped, but usually not more than 0.6 disc diameter, there is good central vision and either a full visual field or only early field loss. Fluorescein angiography shows the loops to be competent with no evidence of any other retinal vascular abnormality. Rarely loss of central vision may occur due to progression to advanced glaucoma. The condition is distinct from prepapillary vascular arterial papillary loops, neovascularization at the optic disc and optociliary shunt vessels. It is also distinct from the venous collateral vessels which develop at the optic disc after acute central or branch retinal vein occlusion. These collaterals are usually multiple, the accompanying ocular hypertension is of lesser degree, cupping of the disc and field loss are usually much more advanced and, while visual acuity may be normal, it is often grossly reduced. On fluorescein angiography all these cases of venous collaterals after retinal vein occlusion showed evidence of other retinal vascular dysfunction. Solitary silent venous papillary loops appear to develop from venules on the optic disc as a bypass to a low grade venous occlusion which is seldom clinically manifest. They form a distinct entity with a good prognosis if the accompanying ocular hypertension is carefully controlled.

Aged↗
PubMed1984

A procedure for studying the organization of peripheral nerves with horseradish peroxidase demonstrated on the facial and hypoglossal nerves in the rat.

The intraaxonal transport of horseradish peroxidase, applied to the proximal stump of different transected hypoglossal and facial nerve branches, was used to label fibers in the hypoglossal main trunk and in the intratemporal portion of the facial nerve in the rat. By using tetramethylbenzidine as a substrate, numerous heavily labeled fibers are obtained. In longitudinal sections the arrangement of fibers can be studied for long distances. From these sections, sites of specific interest can be further examined in transverse-like reconstructions of the nerve. Thus, the procedure described offers a convenient way of analyzing the intrinsic organization of peripheral nerves.

Animals↗
PubMed1983

The organization of the thoracic spinal nerve projection in the rat dorsal horn demonstrated with transganglionic transport of horseradish peroxidase.

Transganglionic transport of horseradish peroxidase (HRP) was used to study the organization of the thoracic spinal nerve projection to the dorsal horn in rats. Labeling was found in the superficial dorsal horn 16-20 hours after application of HRP to the cut ends of various spinal nerve rami. Labeling was restricted to the outer part of the substantia gelatinosa at these stages. Longer survivals (25-48 hours) gave rise to labeling of the deep part of substantia gelatinosa and deeper parts of the dorsal horn as well. The dorsal ramus projected to the lateral third of the horn from half a segment rostral to half a segment caudal to the entry segment. The ventral ramus projected to the medial two-thirds of the horn from 1 1/2 segments rostral to half a segment caudal to the entry segment. The two branches of the ventral ramus that were examined projected to separate medial and lateral compartments for the entire ventral ramus. There was a distinct lateromedial shift of the projection found from rostral through caudal levels within the projection compartment for each nerve. The results indicate that the dorsal horn projection of thoracic spinal nerve branches is organized in longitudinal compartments which are arranged in a strictly somatotopic fashion.

Animals↗
PubMed1983

Demonstration of spinocerebellar projections in cat using anterograde transport of WGA-HRP, with some observations on spinomesencephalic and spinothalamic projections.

Wheat germ agglutinin-horseradish peroxidase (WGA-HRP) conjugate was injected into the lumbar or cervical spinal cord of adult cats in order to examine its usefulness as an anterograde tracer of long ascending spinal tracts. Heavily labeled fibers and terminal-like structures were found in restricted regions of the granular layer of the cerebellar cortex in all animals. The terminal-like structures showed features characteristic of mossy fiber rosettes. Many labeled terminals were found in regions anatomically and physiologically defined as cerebellar hind limb regions after lumbar cord injections. Relatively few labeled terminals were found in both hind limb and in forelimb regions after cervical cord injections. Although the cervical spinal cord is known to project to both hind limb and forelimb regions, it cannot be entirely excluded that some of the labeling in the hind limb regions was derived from uptake by fibers of passage. In addition to labeling in the cerebellar cortex, labeled fibers and terminals were also observed in the cerebellar medial and interposed nuclei, regardless of whether the injections had been made into the lumbar or the cervical spinal cord. Several midbrain and thalamic regions were found to contain labeled fibers and terminal-like profiles in all cases. In the midbrain the periaqueductal gray, the nucleus of Darkschewitsch and the posterior pretectal nucleus contained fairly dense labeling. Labeling was more scattered in the cuneiform nucleus, the mesencephalic reticular formation, the superior colliculus and in the magnocellular part of the medial geniculate body.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

A survey of the nutritional and haemagglutination properties of legume seeds generally available in the UK.

Eighty-five samples from fifteen different legume seed lines generally available in the UK were examined by measurements of their net protein utilization by rats and by haemagglutination tests with erythrocytes from a number of different animal species. From these results the seeds were classified into four broad groups. Group a seeds from most varieties of kidney (Phaseolus vulgaris), runner (Phaseolus coccineus) and tepary (Phaseolus acutifolius) beans showed high reactivity with all cell types and were also highly toxic. Group b, which contained seeds from lima or butter beans (Phaseolus lunatus) and winged bean (Psophocarpus tetragonolobus), agglutinated only human and pronase-treated rat erythrocytes. These seeds did not support proper growth of the rats although the animals survived the 10 d experimental period. Group c consisted of seeds from lentils (Lens culinaris), peas (Pisum sativum), chick-peas (Cicer arietinum), blackeyed peas (Vigna sinensis), pigeon peas (Cajanus cajan), mung beans (Phaseolus aureus), field or broad beans (Vicia faba) and aduki beans (Phaseolus angularis). These generally had low reactivity with all cells and were non-toxic. Group d, represented by soya (Glycine max) and pinto (Phaseolus vulgaris) beans, generally had low reactivity with all cells but caused growth depression at certain dietary concentrations. This growth depression was probably mainly due to antinutritional factors other than lectins. Lectins from group a seeds showed many structural and immunological similarities. However the subunit composition of the lectin from the tepary bean samples was different from that of the other bean lectins in this or any other groups.

Animals↗
PubMed1983

Brainstem projections of different branches of the vestibular nerve. An experimental study by transganglionic transport of horseradish peroxidase in the cat. I. The horizontal ampullar and utricular nerves.

Twenty-seven adult cats were used to study the central projection of the horizontal ampullar nerve and the utricular nerve using transganglionic transport of HRP. The nerve to be investigated was exposed transtympanally, cut, and a capsule containing 50% HRP applied to the proximal stump for one hour; 2-8 days later the animals were perfused. Frozen serial sections were cut from the brainstem and processed for the demonstration of HRP using tetramethyl benzidine as chromogen. Maximal labelling was observed 5-7 days postoperatively. After application of HRP to the horizontal ampullar nerve extensive labelling was found in all four main nuclei except the lateral vestibular nucleus. Furthermore, labelling was observed in the interstitial nucleus of N. VIII, the rostral part of the external cuneate nucleus and in the reticular formation laterodorsal to the abducens nucleus. Small fibers were also seen in the brachium conjunctivum oriented towards the cerebellum, from the superior vestibular nucleus. After exposing the utricular nerve to HRP, labelling was observed in the ventral part of the lateral vestibular nucleus, the central part of the medial vestibular nucleus and in the rostral part of the descending vestibular nucleus. The findings are discussed in relation to known physiological differences between the two kinds of nerves here investigated.

Animals↗
PubMed1982

Hydrolysis of plasma triacylglycerol-rich lipoproteins from immature and laying hens (Gallus domesticus) by lipoprotein lipase in vitro.

Very-low-density (VLD) lipoproteins and portomicrons were isolated from the plasma of immature and laying hens and their size, lipid composition and susceptibility to hydrolysis by lipoprotein lipase were compared. In agreement with other studies, VLD lipoproteins from laying hens were found to be smaller and have a different lipid composition than VLD lipoproteins from immature hens. Portomicrons from immature and laying hens had mean diameters of about 150 nm and similar lipid compositions. Hydrolysis of VLD lipoproteins from immature hens, and portomicrons from immature and laying hens, proceeded rapidly until at least 40% of the substrate had been used. In contrast only 1--15% of laying-hen VLD-lipoprotein triacylglycerol was readily hydrolysis occurred slowly. The limited susceptibility of laying-hen VLD lipoproteins appeared to be due to their low content of lipoprotein lipase activator apoprotein, which occurred despite an abundance of activator in the high-density lipoproteins of laying-hen plasma. The results provide further evidence that the liver of the laying hen synthesizes specialized lipoproteins. Their limited susceptibility to hydrolysis by lipoprotein lipase is probably a major factor in ensuring transport of lipid to yolk rather than to other tissues. The form of transport of dietary lipid, however, is similar in immature and laying hens.

Age Factors↗
PubMed1982

Effect of intramuscular vitamin E on frequency and severity of retrolental fibroplasia. A controlled trial.

126 appropriate-for-gestational age neonates born in hospital with birth-weights of 750 g-1500 g were prospectively studied in a randomised trial to determine the effect of intramuscular vitamin E on the frequency and severity of retrolental fibroplasia (RLF). In the 99 who lived for more than one month the frequency of active RLF in the vitamin E and control groups in the nursery (18.8% vs 23.5%) and at discharge (8.3% vs 19.6% was not significantly different. Vitamin E had significantly reduced the severity of RLF at follow-up eye examination 6-33 months after discharge (p less than 0.01). 3 control infants (760 g, 780 g, 1020 g) were blind in both eyes (grade V cicatricial RLF), whereas the most severe grade of disease in the vitamin E infants was grade II cicatrix. Infants in whom RLF developed were gestationally younger (p = 0.005), required a longer period of mechanical ventilation (p = 0.035), had a greater exposure to oxygen (p = 0.03), and had a greater number of arterial PO2 values between 75 and 99 mm Hg (p = 0.004). Early administration of vitamin E, while not affecting the frequency of RLF, will significantly reduce its severity and subsequent eye damage, and such treatment is recommended for all low-birth-weight infants of less than 1250 g who require supplementary oxygen.

Acute Disease↗
PubMed1982

The location of cerebellar-projecting neurons within the lumbosacral spinal cord in the cat. An anatomical study with HRP and retrograde chromatolysis.

The locations of lumbosacral spinocerebellar neurons were examined by two anatomical methods in kittens. In one group of animals chromatolytic changes were provoked by cerebellar lesions. In another group horseradish peroxidase (HRP) was injected into the cerebellum. Projection laterality was investigated by making unilateral spinal lesions prior to the cerebellar HRP injections. Diaminobenzidine (DAB) or tetramethylbenzidine (TMB) was used as substrate fo HRP. The morphological characteristics of HRP-labeled neurons in the TMB-processed material were examined. Neurons marked by the two methods were located within the same regions. A greater number of cells were marked with the HRP method, however, than with the retrograde chromatolysis method. Spinocerebellar neurons were found in laminae IV-IX with large differences with regard to specific locations depending on segmental level. Numerous marked neurons were found in the following areas: laminae IV-Vi in L3-L7, the column of Clarke in L3-L4, the medial part of lamina VII in L6-L7, the lateral part of lamina VII in L3-L4, the dorsolateral nucleus of lamina IX in L3-L6, the ventrolateral nucleus of lamina IX in L4-L5, and the ventromedial nucleus of lamina IX in S3 (and Ca1). Dorsally located neurons were in general more likely to project ipsilaterally than ventrally located neurons. Marked structural differences were frequently observed between spinocerebellar neurons in different locations. These results provide additional information on the anatomical complexity of the spinocerebellar pathways from the lumbosacral region in the cat. Together with results from some other recent anatomical studies on spinocerebellar tracts, they also form a basis for further anatomical and physiological investigations which could contribute to a better understanding of the organization of the spinocerebellar tracts.

Animals↗
PubMed1982

Dorsolateral spinal afferents to some medullary sensory nuclei. An anatomical study in the cat.

The course and termination of afferents in the spinal dorsolateral fascicle to some medullary sensory nuclei were studied by tracing degeneration following lesions of spinal white matter. The main conclusions depend on successive degeneration experiments; other points were studied with single-stage lesions. The dorsal column nuclei were particularly studied; terminations in these nuclei following dorsolateral lesions followed a clear-cut pattern, with fibres arising from segments below T6 terminating in the gracile nucleus and those with more rostral origin solely in the cuneate nucleus. In both nuclei, the major terminations were in their rostral third with most fibres traversing deep caudal regions where some termination also occurred. Some fibres ended contralaterally. These restricted regions of termination contrasted with the wide-spread terminations seen after lesions of the dorsal column. A region at the cuneate rostral pole, adjacent to but clearly separable from nucleus z, receives a dense projection from both caudal and rostral spinal levels, the former fibres terminating in the dorsal part of the region, the latter extending more ventrally. We treat this as a separate subnucleus. The afferents to the dorsal column (together with those terminating in the other nuclei studied) were confined to the extreme dorsolateral white matter. Our observations confirm the established view that only afferents arising from caudal segments (below at least T 4-5) terminate in nucleus z, and that afferents terminating in group x arise from all levels (at least between C5 and L5): also that neither receives any afferents through the dorsal columns. Dorsolateral fibres arising from segments above at least T6 terminate in a clear-cut area at the lateral border of the external cuneate nucleus. Heavy terminal degeneration was also seen in the lateral cervical nucleus of afferents arising from both above and below T 4-5.

Afferent Pathways↗
PubMed1981

Somatotopic organization of the thoracic spinal nerve in the dorsal horn demonstrated with transganglionic degeneration.

Transganglionic degeneration in primary sensory neurons (TGD) has been studied with the Fink-Heimer and cupric silver methods in the adult rat after transection of thoracic spinal nerve branches. Degeneration was found in the ipsilateral dorsal horn after 13 to 53 days postoperative survival. It was observed in laminae III and IV, inconsistently in lamina I, but not in lamina II (substantia gelatinosa). After transection of the dorsal ramus of the spinal nerve degeneration was seen in the lateral third of the laminae. Transection of the intercostal nerve (ventral ramus) at about the costal angle gave rise to degeneration in the medial two-thirds and transection more distally, at about the mid-clavicular line, in the most medial part of the dorsal horn. The results are in accordance with previous anatomical and physiological studies of the somatotopical organization of the dorsal horn. They clearly show the usefulness of TGD as a tool for analysis of central projections of primary sensory neurons.

Afferent Pathways↗
PubMed1981

Asymmetries and symmetries in the number of thoracic dorsal root ganglion cells.

The right/left ratio for the number of neurons in individual pairs as well as series of pairs of normal rat and guinea pig thoracic dorsal root ganglia have been investigated. After perfusion of the animals with aldehyde fixatives, the 13 pairs of thoracic ganglia were embedded in resin, serially sectioned, and stained with azure methylene blue. Counts of neuronal nucleoli (with correction for possible split nucleoli) were used as an indicator of the number of neurons in each ganglion. In individual pairs the right/left difference varied between 0 and 47% in the rat and 0 and 26% in the guinea pig. There appeared to be no particular level with a preference for large right/left differences. However, when the total number of neurons from the 13 ganglia on one side were compared with the corresponding figure from the other side, the right/left differences were reduced to less than 3% in the rat and less than 2% in the guinea pig. These results show that the organization of the thoracic spinal nerve unit is markedly asymmetrical at the segmental level, but strictly symmetrical in terms of the total number of dorsal root ganglion cells. The marked asymmetry in individual ganglion pairs necessitates caution when evaluating the effect of unilateral experimental manipulations on the number of neurons in thoracic spinal ganglia.

Animals↗
PubMed1979

Further observations on transganglionic degeneration in trigeminal primary sensory neurons.

Transganglionic degeneration has been studied with the Fink-Heimer method in the trigeminal sensory nuclei of adult cats and rats following peripheral nerve transections. Degeneration was observed ipsilaterally as well as contralaterally in all cats, surviving 11-30 days after transection of the infraorbital nerve. In the rats the infraorbital or the auriculotemporal nerve was transected. After transection of the former nerve the first signs of transganglionic degeneration were observed after 7 days postoperative survival and even after 130 days there were still a lot of degenerating structures present. Between 7 and 14 days survival there was a small amount of degeneration in substantia gelatinosa. After transection of the auriculotemporal nerve, degeneration was observed only in the most caudal parts of the trigeminal sensory nuclear complex. Opposite to the situation in the cat, there was no contralateral degeneration in the rat. All degeneration areas were somatotopically organized, both in the cat and in the rat. The results are discussed in relation to a previous study of transganglionic degeneration in the trigeminal sensory nuclear complex by the authors and to anatomical and physiological studies of somatotopic organization in the trigeminal sensory nuclei. They clearly show the value of transganglionic degeneration used as a tool for analysis of central projections of primary sensory neurons.

Age Factors↗