Biomedical subjects
Publications and source records attributed to F Collins.
A case of malignant melanotic schwannoma arising in the right upper lobe bronchus of a 27 year old man is presented. Tumours of this type most commonly occur in spinal nerve roots and are generally considered to be benign. The behaviour of those originating elsewhere is less predictable. As far as we are aware this is the first reported case affecting the respiratory tract.
Nerve growth factor (NGF) is present in high concentrations in the rat hippocampal formation where it may be involved in sympathetic sprouting following septohippocampal denervation. In addition, recent evidence suggests that some forebrain cholinergic neurons, including septohippocampal neurons, are responsive to exogenous NGF. Since septohippocampal neurons have been shown to sprout in response to entorhinal lesions both in rats and, recently, in humans, we sought to determine whether endogenous NGF-like activity increases in the rat hippocampal formation following injury to the entorhinal cortex. We found that entorhinal lesions which result in extensive denervation of the dentate granule cells, and subsequent sprouting of septohippocampal axons, do result in greater NGF-like growth-promoting activity in medium conditioned by slices of the denervated tissue when compared to medium conditioned by control tissue. These results suggest that brain NGF may be involved in injury-induced sprouting of forebrain cholinergic neurons.
The survival of dissociated ciliary ganglion neurons is promoted by extracts of several different embryonic and adult tissues from two species. The survival-promoting activity in each of these extracts survives exposure to sodium dodecyl sulfate (SDS) and sulfhydryl-reducing agent and can, therefore, be subjected to SDS-polyacrylamide gel electrophoresis. Upon electrophoresis, the survival-promoting activity is recovered in a discrete peak at an apparent molecular weight of approximately 21,800 for all of the tissues examined. These results suggest that a similar molecule in each of these different tissues and species may be responsible for their ability to promote the survival of ciliary ganglion nerve cells in culture.
Conditioned medium prepared from slices of the rat hippocampal formation contains an agent that shares the following properties with nerve growth factor (NGF): it promotes neurite growth from embryonic sympathetic ganglia in vitro; and it is inhibited by affinity-purified antibody against mouse submaxillary gland 2.5 S NGF. The NGF-like growth-promoting activity is regionally distributed within the hippocampal formation: the activity is consistently higher in the dentate gyrus-CA3 region than in the CA1 region. Furthermore, the level of activity is significantly increased within 1 week after a medial septal lesion, and, in the dentate-CA3 region, the increased level of activity is maintained for at least 4 weeks after the lesion. Control lesions that fail to interrupt the septohippocampal innervation, but cause equally extensive damage to nearby regions of the central nervous system, do not cause increased levels of activity in the hippocampal formation. These results provide substantial evidence linking the NGF-like agent in hippocampal conditioned medium to the sprouting of sympathetic axons into the dentate gyrus-CA3 region of the hippocampal formation after a medial septal lesion in vivo.
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Techniques are described for forming on the culture substrate a narrow pathway of material derived from medium conditioned by embryonic non-neuronal cells. There is a precise correlation between the known location of the pathway and the spatial distribution of neurites extended from whole ciliary ganglia or dissociated neurons grown on the patterned substrate. When individual growth cones moving on the pathway contact one of its edges, they turn sharply so as to remain on the pathway. This turning response is not simply due to a physical barrier to movement across the edge, since growth cones can cross onto the pathway when entering from the adjacent untreated substrate. The strong preference for neurites to maintain contact with the pathway also is not simply a result of their inability to survive or elongate outside of the pathway, since neurites from whole ganglia elongate readily on other regions of the substrate, although their growth is then undirected. Direct contact with the pathway is required for these directive effects, and there is no indication that the material bound to the substrate diffuses off and exerts its effects at a distance. The neurite-guiding activity is found in partially purified fractions of conditioned medium which also contain a substrate-bound inducer of neurite outgrowth. It is possible that both activities may be due to the same components of conditioned medium. These results suggest that ciliary ganglion growth cones are able to detect specific components of conditioned medium on the substrate and respond to their presence by changing their direction of movement so as to remain in contact with these components.(ABSTRACT TRUNCATED AT 250 WORDS)
Mouse submaxillary nerve growth factor (NGF) increases the length and density of neurites extended from embryonic chick ciliary ganglia in vitro. The effect is not as pronounced as with dorsal root ganglia, but it occurs at the same low concentrations of NGF. This effect was observed on polyornithine substrata with or without pretreatment of the substratum with conditioned medium. NGF did not significantly increase the length or density of neurites extended from spinal cord or neural retina explants in the same culture conditions. Stimulation of ciliary ganglion neurite outgrowth did not occur when NGF was replaced with cytochrome c or epidermal growth factor, whereas insulin had an effect comparable to that of NGF when present at much higher concentrations. Four different purified preparations of NGF gave identical results. The purity of two of these preparations was determined after radioiodination; greater than 98% of the radioactivity migrated as a single band on polyacrylamide gels, and greater than 94% of the radioactivity was bound by affinity purified anti-NGF antibody. The effect of NGF on neurite growth could be separated from its effect on neuronal survival. NGF failed to promote the survival of ciliary ganglion neurites even at concentrations 1000-fold higher than those which significantly stimulated neurite growth.(ABSTRACT TRUNCATED AT 250 WORDS)
Addition of nerve growth factor (NGF) to dissociated parasympathetic ciliary ganglion neurons resulted, within 60 min of its addition, in a 2-fold increase in average neurite length and an accompanying enlargement and spreading of neuronal growth cones. These effects occurred over a concentration range of NGF of 0.1-10 ng/ml and were blocked by affinity-purified antibody to NGF. Epidermal growth factor, fibroblast growth factor, and angiotensin did not have these effects, although insulin at high concentrations was able to induce a response similar to that of NGF. Dissociated sympathetic chain neurons also responded to NGF with increased neurite lengths, and, in addition, NGF considerably extended the survival time of these neurons in culture. However, the effect of NGF on ciliary ganglion neurons was limited to neurite outgrowth, and NGF did not promote the survival of these parasympathetic neurons.
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The rat hippocampal formation was tested for the presence of factors that would accelerate neurite extension from chick parasympathetic (ciliary ganglion) or sympathetic (lumbar chain) neurons in vitro. Two growth factors were identified in extracts of this brain region. One accelerated neurite extension from sympathetic neurons and was blocked by antiserum to nerve growth factor. The other accelerated neurite extension from parasympathetic neurons but was not affected by the antiserum. These results suggest that specific growth factors account for the specificity of neuronal sprouting.
From stages 35 to 40 in the chicken embryo, ciliary ganglion neurons undergo a developmental change which is detected in our assay system as a marked decline in the ability to extend neurites when placed in culture. This developmental loss is observed when the neurons are placed in culture as single, dissociated cells or as undissociated ganglion explants. The loss of the ability to extend neurites in culture is not a transitory phenomenon, for no recovery of this ability is observed during the rest of embryonic development or posthatching. There is a close temporal correlation between the embryonic period during which the ability of ciliary ganglion neurons to extend neurites declines and the period (stages 35 to 40) when these neurons form functional peripheral synapses in the embryo. The ability to extend neurites rapidly is not recovered during normal development as long as the ganglion and its connections within the organism remain intact. However, if the ciliary ganglia are removed from a stage 40 embryo and cultured for 3 to 4 days before being dissociated, the neurons have largely recovered their ability to initiate neurite outgrowth rapidly. This recovery after removal from the embryo is also presumably responsible for the eventual dense outgrowth of neurites from stage 40 ganglion explants after a 3- to 4-day delay in culture. Our results, in conjunction with similar results from other systems, suggest a cause and effect relationship between the establishment or disruption of peripheral connections and the loss or recovery, respectively, of the ability to extend neurites rapidly.
Heart cell-conditioned medium supports extensive neurite outgrowth from dissociated parasympathetic neurons of the chicken embryo ciliary ganglion. We have shown previously that neurite outgrowth in this system depends on the deposition of a substratum-conditioning factor from conditioned medium onto the polyornithine culture substratum. However, in the presence of only the substratum-bound material, neurite outgrowth is never as extensive as in whole conditioned medium. The present report demonstrates that a different and soluble component of conditioned medium is required to achieve the rates of neurite elongation normally observed in whole conditioned medium. This second component, while unable by itself to support neurite outgrowth, is able to increase the rate of neurite elongation approximately 3-fold within 30 to 60 min of its addition. This conclusion is based on direct time-lapse observations of the rate of elongation of individual neurites before and after the addition of fractions of conditioned medium previously depleted of the substratum-conditioning factor. Correlated with the effect of such fractions of conditioned medium on the rate of neurite elongation is a change in the morphology of the growth cones, which become larger and more spread. The activity of the soluble, elongation-promoting component of conditioned medium is nondialyzable and is sensitive to treatments known to affect proteins, such as repeated freeze-thawing, heating, and trypsinization. Fractions of conditioned medium which contain the elongation-promoting activity also contain all of the survival factor for parasympathetic neurons previously shown to be present in heart cell-conditioned medium. The methods described here represent a convenient new assay which we have used recently to demonstrate elongation-promoting factors with neuronal specificity in extracts of rat hippocampus.
Comparisons were made between frontalis EMG surface recordings concurrently taken from horizontal, right vertical, and left vertical electrode placement configurations. Six migraine and seven tension headache patients were used as subjects. Results showed that, in general, a positive correlation existed between recordings from the three placements for both migraine and tension subjects as a group. However, marked individual differences were noted. It was concluded that electrode placement can be quite important in measuring changes in frontalis muscle tension for headache patients.
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Dissociated parasympathetic neurons rapidly initiate neurite outgrowth when exposed to culture medium previously conditioned by the growth of embryonic heart cells. The inducer of neurite outgrowth in the conditioned medium is a substratum-conditioning factor; that is, it does not act in a soluble form, but acts only when bound to the nerve cell culture substratum. When a sharp border is created between a region of the substratum coated with this factor and a region coated with unconditioned medium, neurites fail to cross this border; rather, they change their direction of outgrowth so as to remain on the conditioned substratum. Thus, long after the initiation of outgrowthhas been induced, elongating neurites continue to respond to the substratum-conditioning factor in a manner that allows their outgrowth to be channeled along a pathway of this neurotropic substratum-associated material.
HTG2 hamster cells produce a defective murine sarcoma virus lacking gp70 and, consequently, viral surface projections (knobs), but the lack of knobs appears to have no effect on intramembrane particle distribution. In addition, it has been noted that the core of the virus remains in the "immature" form as a result of the failure of the polyprotein precursor (p65) to undergo cleavage. However, incubation of HTG2 virus with avian myoblastosis virus was found to yield specific cleavage products of p65.