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Biomedical subjects

D McLeod

Publications and source records attributed to D McLeod.

At least 181 records · Page 10Linked to original sources
PubMed1987

Retinal relieving incisions.

Retinal relieving incisions were undertaken during closed microsurgery for the treatment of retinal detachment complicated by retinal shortening as a result of incarceration or irresectable epiretinal membranes. In 16 of 20 eyes the retina remained attached after a minimum follow up of six months. Visual acuity of 2/60 or better was achieved in eleven of the 20 eyes and seven eyes had an acuity of 6/60 or better. Retinal relieving incisions are required in a minority of retinal re-attachment procedures and are compatible with useful visual function.

Adult↗
PubMed1986

Interleukin 3 and cell cycle progression.

Interleukin 3 (IL-3) is a regulatory glycoprotein required for the proliferation and differentiation of cells from many if not all hemopoietic lineages. With the emergence of the competence-progression model of cell proliferation, which predicts that growth factors function at specific stages of the cell cycle, we examined the possibility that IL-3 functions at a specific stage of the cell cycle. C-63 cells were developed as a cell line from normal murine bone marrow. They have a mast cell phenotype and require pokeweed-stimulated spleen cell-conditioned medium (CM), a rich source of IL-3, for their continued growth. Exponentially growing cells were transferred from growth medium, which contains CM, to medium lacking CM or IL-3. After 24 hours, cell viability had decreased 40-50%. The remaining viable cells did not incorporate 3H-thymidine, and displayed a single peak at G1 in a DNA histogram. Restimulation of these cells with CM or IL-3 resulted in a dramatic rise in 3H-thymidine uptake 20-24 hours after restimulation. DNA histograms of restimulated cultures indicated that the cells were progressing in a wave-like fashion throughout the remainder of the cell cycle. The length of time necessary for cells to be in contact with CM or IL-3 before they could progress into the remainder of the cell cycle was also examined. Cells incubated with CM or IL-3 for less than 16 hours could not progress into S phase, whereas cells incubated for 16 hours or longer could progress into S phase and through the remainder of the cell cycle. These data suggest that IL-3 exerts its function at a specific stage of the cell cycle.

Animals↗
PubMed1986

Silicone-oil injection during closed microsurgery for diabetic retinal detachment.

A beneficial visual outcome was achieved in 16 (38%) of 42 eyes into which silicone oil was injected after difficulties were encountered during closed microsurgery for severe diabetic retinal detachment. Without recourse to oil injection, most if not all of the eyes would have remained blind and many would have deteriorated into rubeotic glaucoma or phthisis. The main cause of failed surgery was rhegmatogenous retinal detachment associated with residual or reparative epiretinal fibrosis, and silicone oil appeared to be of value in preventing rubeosis iridis in such cases. Cataract was a significant problem in the successfully treated eyes.

Diabetic Retinopathy↗
PubMed1986

Xenon-arc endophotocoagulation during vitrectomy for diabetic vitreous haemorrhage.

The value of scatter xenon-arc endophotocoagulation in stabilising eyes with respect to post-operative rubeosis iridis and vitreous haemorrhage is demonstrated in a consecutive series of 100 vitrectomies undertaken for diabetic vitreous haemorrhage. Seventy eyes ultimately achieved 6/36 or better vision. Endophotocoagulation of untreated ischaemic retina is recommended in eyes undergoing vitrectomy for diabetic vitreous haemorrhage.

Diabetes Complications↗
PubMed1986

Human retinal pigment epithelial cells in the vitreous of the owl monkey.

Cultured human retinal pigment epithelium was injected into the vitreous of owl monkeys. The epithelial cells were derived from either a foetal or an adult cell line. The five monkeys which were injected with cultured foetal cells developed substantial vitreal membranes and had retinal detachment by 2 weeks, whereas the five monkeys with cultured adult cells did not develop detachments within the period of investigation, and vitreal membranes were insubstantial. An electron-microscopic, immunohistochemical and autoradiographic study was conducted on these eyes to investigate in detail the behaviour and intraocular effects of the injected cells.

Adult↗
PubMed1986

Congenital cataract surgery: a retinal surgeon's viewpoint.

Rhegmatogenous retinal detachments presenting many years after surgery for congenital cataracts frequently present formidable problems in management. The techniques and results of treatment are being presented and the implications for modern-day congenital cataract surgery are discussed.

Cataract↗
PubMed1986

Fresh retinal detachments--the role of scleral buckling.

Current concepts and methods of scleral buckling for fresh rhegmatogenous retinal detachments are reviewed in the light of alternative or additional approaches to retinal reattachment surgery. Increasingly, in difficult detachments, temporary internal air tamponade is replacing scleral buckling as a means of achieving initial closure of superiorly-located retinal breaks, though buckling often retains a role in thereafter maintaining break-closure by withstanding persisting vitreoretinal traction. Vitrectomy is also being employed more frequently in fresh detachments in order to relieve vitreoretinal traction, remove vitreous opacities and provide extra space for internal gas injection; however, complete relief of traction in the retinal periphery is seldom achievable, thus necessitating scleral buckling.

Humans↗
PubMed1985

A self-renewing, bipotential erythroid/mast cell progenitor in continuous cultures of normal murine bone marrow.

We have established permanent lines of nonadherent cells from fresh normal mouse bone marrow in media containing pokeweed mitogen-stimulated spleen cell conditioned medium (PWSCM). These lines continuously produced erythropoietic progenitor cells (detected by their ability to form erythroid bursts in semi-solid medium containing erythropoietin) together with cells having characteristics of the mast cell lineage (as demonstrated by metachromatic staining with toluidine blue, histamine content and membrane receptors for IgE). Sixteen such cell lines have been established in sixteen attempts. Cloning experiments were carried out to determine the nature of the progenitor cell(s) responsible for the permanence of these cultures. When cells were cultured in methylcellulose medium containing PWSCM, colonies were observed which reached macroscopic size after 4 weeks of incubation. Replating of individual primary colonies resulted in secondary colony formation, indicating the presence of progenitor cells with self-renewal potential. Forty-seven primary colonies were picked and their cells were suspended in liquid culture medium containing PWSCM. Of these, twenty-one could be expanded to establish permanently growing sublines. Sixteen of these sublines were found to be composed of both erythroid progenitors and mast cells. In five sublines only mast cells could be seen; none of the sublines appeared to be purely erythroid. Karyotypic analysis of mast cells and of erythroid cells of seven sublines derived from individual colonies which arose in cocultures of male and female cells revealed that the mast cells and erythroid cells were both of the same sex in each of the seven sublines; this demonstrates the single cell origin of each colony and of the two lineages derived from it. We conclude that these nonadherent, factor-dependent cell lines are maintained by self-renewal and differentiation of bipotential progenitor cells apparently restricted to the erythroid and mast cell lineages.

Animals↗
PubMed1985

D-ACE surgical sequence for selected bullous retinal detachments.

Forty-five out of 50 selected retinal detachments were successfully reattached by the D-ACE surgical sequence, that is, initial drainage of subretinal fluid followed by air injection into the vitreous, transcleral cryopexy, and definitive scleral buckling. The D-ACE sequence is recommended for difficult bullous detachments as a simple, safe, and effective alternative to non-drainage techniques.

Air↗
PubMed1985

Natural history of fibrocellular epiretinal membranes: a quantitative, autoradiographic, and immunohistochemical study.

Quantitative, autoradiographic, or immunohistochemical light microscopy was conducted on 85 surgically excised epiretinal membranes to investigate the activities of component cells and the natural history of the extraretinal scars. Membranes of less than four months' clinical duration ('early' membranes) contained significantly more cells than 'late' membranes, while collagen was more abundant in the older specimens. No correlation was established between membrane opacification and either the cellularity or the collagen content of the membranes. Epiretinal membranes had some features in common with healing skin wounds, but the activities of cells in the epiretinal membranes were relatively protracted and disordered. Fibronectin was found to be a significant component of epiretinal membranes and therefore represents a target at which pharmacological intervention could be aimed.

Actins↗
PubMed1985

Reparative epiretinal fibrosis after diabetic vitrectomy.

Closed microsurgery for the haemorrhagic and tractional sequelae of proliferative diabetic retinopathy is frequently successful in restoring and maintaining useful vision. Severe complications may arise, however, including the reproliferation of cellular membranes on the retinal surface with subsequent retinal distortion or redetachment. The clinical and histopathological features of such reparative epiretinal fibrosis are presented and methods of prevention are discussed.

Diabetic Retinopathy↗
PubMed1985

Management of retinal detachment in the Wagner-Stickler syndrome.

Thirty six retinal detachments in 33 patients with Wagner-Stickler syndrome are reported. The results of surgery are correlated with the types of break (giant retinal tear or multiple breaks), the surgical approach (conventional buckling or closed microsurgery) and the presence or absence of proliferative vitreoretinopathy. Overall, 27 detachments were successfully reattached.

Abnormalities, Multiple↗
PubMed1984

Closed microsurgery in trauma.

Blunt and penetrating injuries to the eye provide ophthalmologists with a wide range of surgical challenges. The reconstruction and visual rehabilitation of traumatized eyes are described with particular emphasis on the role of closed microsurgical techniques in the posterior segment.

Eye Injuries↗
PubMed1984

Retinal and epiretinal glia--an immunohistochemical study.

Immunohistochemical techniques were used to examine the distribution of cells containing glial fibrillary acidic protein (GFAP) in normal and pathological human specimens, including 22 globes (13 of which contained epiretinal membranes 'in situ'), 16 surgically excised epiretinal membranes, and monolayers of cells obtained from five epiretinal membranes placed in tissue culture. The astrocytic cells of normal and pathological retinae stained with the glial-cell marker, but Müller cells were GFAP-negative in normal retinae at the antisera dilutions used. Müller cells did, however, stain in retinae from glaucomatous eyes and in eyes with prolonged retinal detachment. Electron microscopy did not reveal any obvious morphological difference between the intermediate filaments of normal (GFAP-negative) and GFAP-positive Müller cells. Ten of the 13 epiretinal membranes 'in situ', all 16 excised membranes, and three of the five monolayers contained glial cells. Purely glial membranes were not associated with retinal puckering or detachment, while all membranes causing tractional complications had a prominent fibrous, non-glial component. Our findings suggest that glial cells do not contribute significantly to the contractile forces generated by epiretinal membranes. They may, however, provide a scaffold on which other cells proliferate and contract and an anchorage by means of which tangential forces are transmitted into and through the retina.

Adolescent↗