PubMed Health⌕ Search

Biomedical subjects

E B Davis

Publications and source records attributed to E B Davis.

12 recordsLinked to original sources
PubMed1992

Effects of cholinergic and adrenergic agonists on adenylate cyclase activity of retinal microvascular pericytes in culture.

Pericytes are contractile cells that might help regulate microvascular blood flow. To understand their potential role in the regulatory responses of the retina and optic nerve head vessels, the response of pericytes isolated from bovine retinal microvessels was determined to oxotremorine, isoproterenol, phenylephrine, and clonidine. Isoproterenol doubled the basal levels of cyclic adenosine monophosphate (cAMP) specifically through beta-adrenergic receptors, because the effect was blocked by dl-propranolol. The alpha 1 agonist phenylephrine did not induce any major change in adenylate cyclase activity. The alpha 2 agonist clonidine decreased basal cAMP synthesis and reduced the effect of isoproterenol. The cholinergic agonist oxotremorine did not modify the basal activity of adenylate cyclase but was able to decrease by almost 50% the forskolin-induced increase of cAMP. These results suggest that pericytes have functional adrenergic and cholinergic receptors, and they might respond to autonomic vasoactive substances present in vivo.

Adenylyl Cyclases↗
PubMed1991

Angiotensin II binding receptors in retinal and optic nerve head blood vessels. An autoradiographic approach.

Angiotensin II (AII) binding sites were identified in cross-sections of the cat retinal and optic nerve vasculatures. The authors used 3H-AII and 125I-saralasin, an agonist and a high-affinity antagonist of AII receptors, respectively, to generate light microscopy autoradiograms in resin-embedded tissues. With both radioligands the presence of AII binding sites was confirmed in retinal arterioles but not in the veins or capillaries of the retina. Additionally the presence of such binding sites in the capillaries of the optic nerve head was shown. These results support the hypothesis that microvascular tone and perhaps autoregulatory responses of optic nerve capillaries might be influenced by vasoactive substances, such as AII, either leaking from the choroid or locally synthetized.

Angiotensin II↗
PubMed1979

Mental illness in blacks: an overview, and treatment approaches.

Provisions for inner city mental health services must recognize the association between poverty, discrimination, and related social and physical conditions and disproportionately high rates of severe mental disorder-a transcultural phenomenon.Program emphasis should therefore be on the prevention, early recognition, prompt and effective treatment and rehabilitative care of psychosis. The total spectrum of psychiatric services is required for this, and thus an opportunity is afforded for necessary training and research.Poverty has negative impact on general health and cognitive development as well as on self-esteem, self-care, and the ability to utilize medical and health services. This contributes to a vicious, intergenerational poverty cycle.Primary prevention of mental illness, where possible, depends at present on socioeconomic change. Secondary prevention, ie, timely, appropriate treatment, is effective, but requires patient access to and acceptance of all indicated modalities of care.

Black or African American↗
PubMed1978

Herpes simplex retinitis.

Fatal encephalitis with accompanying retinitis developed in a previously healthy 18-month-old infant. Clinically the disease appeared as whitish-yellow punctate lesions, perivascular cuffing, and hemorrhage. The antibody titer to herpes simplex rose from 1:8 on the day of admission to 1:256 on the day of death. Postmortem, intranuclear inclusion bodies that were typical of those found with herpesvirus were seen in the brain and retina. Viral particles consistent with those of herpesvirus were found by electron microscopy in the brain and in the inner-nuclear and ganglion-nerve fiber layers of the retina. This demonstrates the direct infectious nature of herpetic retinitis. Hematogenous spread of the virus to the retina is presumed.

Brain Stem↗
PubMed1978

The decision to hospitalize.

The authors explored determinants of psychiatric hospitalization in four Manhattan general hospital emergency rooms and found that although the nature and severity of a patient's problem played the most important role in the decision to hospitalize, the facility involved was also a determining factor. The findings are discussed in relation to policy concerning staffing and organization of emergency room services and future studies of service delivery in this area.

Adult↗
PubMed1977

Descending optic nerve degeneration in primates.

We cut the optic nerve at the orbital apex in squirrel monkeys to study the descending degeneration of optic nerve axons and their ganglion cell bodies. We could not detect progressive disintegration of the axon from the site of injury back to the cell body. Instead, the entire length of individual axons seemed to degenerate simultaneously as early as 3 weeks and as late as 6 weeks after injury, as judged both by ultrastructural integrity and by continued slow axonal transport, a reflection of local physiologic function. We could not relate the time of degeneration to the distance of the injury from the cell body. Evidently there is a signal of injury to the cell body after axotomy, though the nature of the signal and the mechanism by which it leads to cell death are unknown.

Animals↗
PubMed1977

A two-phased model for library instruction.

This article describes two methods of library orientation and instruction: self-paced audiotapes and computer-assisted instruction (CAI). The tapes are used to orient the user to the libraries' physical facilities, policies, services, and tools, while CAI is used to provide detailed library information in an interactive mode.

Audiovisual Aids↗
PubMed1975

Sensitivities of ocular tissues to acute pressure-induced ischemia.

Intraocular pressure was artificially elevated for eight hours in eight owl monkeys. The first permanent effect (produced at a perfusion pressure of plus 15 mm Hg) was partial necrosis of iris stroma and ciliary processes, associated with microscopic lesions in the photoreceptors and retina pigment epithelium around the disc and in the retinal periphery. At a slightly higher pressure, visual nerve fibers in the retina and optic nerve and their ganglion cells were affected. Simultaneously, the outer retinal layers showed damage to the pigment epithelium, photoreceptors, and other nuclear layers. At even higher pressures, nearly all the other intraocular tissues were affected except for Müller cells, astroglia in the optic nerve head, epithelium of the pars plana, and the pigment cells of the choroid. The possibility is raised of a nonischemic pressure-induced mechanism for destruction of disc astrocytes in human chronic glaucoma.

Acute Disease↗