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Biomedical subjects

L A Cunningham

Publications and source records attributed to L A Cunningham.

9 recordsLinked to original sources
PubMed1992

Auditory-visual word identification test materials: computer application with children.

The purpose of this investigation was to obtain performance data from normal-hearing children using the written word portion of existing auditory-visual word identification materials, for example, the Picture Identification Task (Wilson and Antablin, 1980). The response foils, consisting of four written words (target and alternative words) were entered into computer memory so that responses were made by pointing to a computer monitor. Subjects were 24 fourth graders with normal hearing who repeated auditory-stimulus words in noise in oral conditions, and pointed to written words representing the stimulus words in pointing conditions. Mean percent correct performance scores were higher in the pointing conditions than in the oral conditions, reflecting closed- versus open-set tasks. The results indicated that the written word portion of the Picture Identification Task can be utilized to assess the word identification performance of children who read at a fourth grade level or above.

Audiovisual Aids↗
PubMed1991

The use of genetically altered astrocytes to provide nerve growth factor to adrenal chromaffin cells grafted into the striatum.

Transplantation of adrenal chromaffin cells into the striatum of Parkinson's disease patients is unlikely to become a reliable therapy unless techniques are devised to improve cell survival. To address this issue, we investigated the use of genetically altered astrocytes that constitutively secrete beta-nerve growth factor (NGF) to provide trophic support for adrenal chromaffin cells grafted into the dopamine-denervated striatum of the rat. Primary rat astrocytes were altered genetically in vitro by infection with a retroviral vector harboring a mouse beta-NGF transgene under constitutive long terminal repeat transcriptional control. Confluent cultures of these genetically altered astrocytes secrete NGF into their culture medium at a rate of approximately 9 pg/10(5) cells/h. This rate of NGF secretion is at least 10-fold higher than that of confluent sister cultures of uninfected astrocytes. The effects of the NGF-secreting astrocytes on the survival and neuronal transformation of dissociated adrenal chromaffin cells were assessed in vitro and following transplantation into the dopamine-denervated striatum of the adult rat. In vitro experiments demonstrated that neuritic outgrowth is stimulated when postnatal day 12 chromaffin cells are grown on a monolayer of the genetically altered astrocytes. When co-grafted with genetically altered astrocytes, young postnatal chromaffin cells displayed extensive neuritic outgrowth within the host brain 2 weeks postimplantation, whereas chromaffin cells grafted alone or with normal astrocytes retain an endocrine-like morphology. Survival of the chromaffin cells is also enhanced 3-6-fold when co-grafted with the genetically altered astrocytes. In addition, the neuronally transformed chromaffin cells appear to lose adrenergic properties as assessed by diminished immunoreactivity to the adrenergic marker, phenylethanolamine-N-methyltransferase. Although their survival is also enhanced approximately 4-fold relative to controls, adult chromaffin cells do not convert to a neuronal morphology when co-grafted with the genetically altered astrocytes. These studies demonstrate that rat astrocytes carrying a mouse NGF transgene provide trophic support for intrastriatal chromaffin cell grafts.

3T3 Cells↗
PubMed1991

Survival and differentiation within the adult mouse striatum of grafted rat pheochromocytoma cells (PC12) genetically modified to express recombinant beta-NGF.

Rat pheochromocytoma PC12 cells were genetically modified in vitro to express recombinant beta-nerve growth factor (beta-NGF) using a replication-deficient retroviral vector carrying the mouse beta-NGF gene and subsequently implanted into the striatum of a mouse model of Parkinson's disease. The fate of the genetically modified PC12 cells (PC12N.8) was assessed at varying times postimplantation by studying immunoreactivity (IR) to tyrosine hydroxylase (TH) or the rat NGF receptor (NGFR). In vitro, the genetically modified PC12 cells displayed a neuronal morphology in the absence of exogenous NGF which was characterized by extensive neurite outgrowth. In addition, the genetically modified PC12 displayed a catecholaminergic phenotype in vitro as assessed by TH-IR. Following implantation into the striatum, the survival of PC12N.8 cells was limited. Surviving cells could be identified by NGFR-IR, but not by TH-IR. In addition, PC12N.8 cells with a neuronal morphology similar to that observed in vitro were only rarely observed in vivo. No tumors were observed in PC12N.8 graft recipients up to 30 days postimplantation. In contrast, intrastriatal tumors were observed in 50% of the PC12 cell recipients. These data demonstrate that PC12 cells genetically modified in vitro to synthesize beta-NGF do not revert to the mitotic phenotype of the parent PC12 cell line following implantation into the adult striatum, an observation that suggests that these cells may continue to express recombinant beta-NGF in vivo. The data further suggest that the genetically modified PC12 cells lose the catecholaminergic phenotype following implantation into the striatal parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗
PubMed1988

Vasoactive intestinal peptide stimulates adrenal aldosterone and corticosterone secretion.

Vasoactive intestinal peptide (VIP)-immunoreactive nerve fibers have been demonstrated in the rat adrenal cortex in close association with zona glomerulosa cells, suggesting neural regulation of adrenocortical cell function (5). The present studies were undertaken to study the possible role of VIP in the regulation of steroid hormone secretion from the outer zones of the normal rat adrenal cortex. Capsule-glomerulosa preparations, consisting of the capsule, zona glomerulosa, and a small but variable portion of the zona fasciculata, were perifused in vitro. To assess the secretory responsiveness of the capsule-glomerulosa preparation, aldosterone and corticosterone release were measured after stimulation with ACTH and angiotensin II. ACTH (10(-12)-10(-8) M) stimulated dose-dependent increases in aldosterone secretion (1.9- to 36.9-fold increases over basal values) and corticosterone secretion (1.4- to 14.0-fold increases over basal values). Angiotensin II (10(-8)-10(-5) M) stimulated dose-dependent increases in aldosterone secretion (1.6- to 8.8-fold increases over basal values). VIP (10(-6)-10(-4) M) stimulated dose-dependent increases in both aldosterone (1.7- to 41.0-fold) and corticosterone secretion (1.8- to 5.3-fold). However, glucagon and (N-Ac-Tyr1-D-Phe2)GRF-(1-29)NH2, peptides structurally related to VIP, stimulated neither aldosterone nor corticosterone secretion, indicating that VIP effects are likely to be specific for this peptide. It is noteworthy that in this preparation, the stimulation of corticosteroid secretion by VIP at 10(-5) and 10(-4) M was comparable to those by 10(-6) M angiotensin II and 10(-9) M ACTH, respectively. These results support the hypothesis that the VIP innervation of the adrenal cortex may contribute directly to the regulation of adrenal steroidogenesis.

Adrenal Cortex↗
PubMed1987

The role of adrenal nerves in the regulation of adrenocortical functions.

There is now convincing evidence for the distribution of several nerve plexuses in the outer zone of the adrenal cortex. At the ultrastructural level, the close proximity of nerve boutons to cortical cells establishes the anatomical substrate for a direct neural effect on adrenal cortical cell functions. Of those neurotransmitters and neuropeptides identified to date, catecholamine, VIP, and NPY appear to be most prevalent. Importantly, the amounts of morphologically identifiable catecholamine, VIP and NPY are differentially sensitive to alteration of several physiological conditions. Furthermore, the VIP plexus appears to be intrinsic to the adrenal while the catecholamine and NPY nerve fibers enter the adrenal along blood vessels. Together, these results suggest that these multiple nerve plexuses might exert control on several adrenocortical cellular processes in addition to the regulation of adrenal blood flow. Compensatory adrenal growth, a rapid proliferative response to unilateral adrenalectomy, was previously shown to be neurally mediated. The role of the catecholamine innervation in the mediation of this process has now been demonstrated. The elimination of the sympathetic nervous system by neonatal sympathectomy inhibited the proliferative response as measured by DNA synthesis. In vivo administration of beta-adrenergic receptor blockers did not inhibit the compensatory growth response. Furthermore, the beta-adrenergic agonist isoproterenol, inhibited the rate of DNA synthesis both in vivo and in vitro. The direct action of the beta-adrenergic agonist on the adrenocortical cell DNA synthesis rate suggests that the catecholaminergic nerves tonically inhibit cell proliferation associated with compensatory growth and that the release from the beta-adrenergic inhibition is necessary for compensatory growth. Whether inhibition of the beta-adrenergic innervation is the trigger for compensatory growth or whether it is permissive to the action of a still unidentified mitogenic substance, is not yet known. The direct role of VIP and catecholamines in the regulation of steroidogenesis has been investigated in vitro using the perifused capsule-glomerulosa preparation which is representative of a normal outer zone of the adrenal and is the site of the neural plexuses and identified receptors. Both VIP and isoproterenol stimulate steroidogenesis and specifically cause a greater increase in secretion of aldosterone than corticosterone. Although the concentrations of VIP and isoproterenol required to stimulate steroidogenesis are greater than reported circulating levels, release from resident nerves could provide high local concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Cortex↗
PubMed1975

The effect of modified ECT on serum creatine phophokinase, I. With intravenous atropine.

Interpretation of serum creatine phosphokinase (CPK) levels is frequently difficult because of complicating circumstances known themselves to raise CPK; for instance, intramuscular injections. One such circumstance among psychiatric patients is said to be administration of electroconvulsive therapy (ECT). In a series of 22 patients who received drug modified ECT, four had CPK elevations beyond the normal range. These findings indicate that CPK elevations among patients receiving ECT should be interpreted cautiously.

Adolescent↗
PubMed1975

The effect of modified ECT on serum creatine phosphokinase. II. With subcutaneous atropine.

In the previous study, the effect of modified ECT on serum CPK was investigated. In that study, atropine was administered intravenously two minutes prior to ECT being given. In this study, the more usual clinical procedure in which atropine is administered subcutaneously is investigated. In a series of nineteen patients, four had CPK elevations beyond the normal range. These findings resemble the findings of the previous study closely, and indicate again that elevations of CPK in patients receiving ECT should be interpreted with caution.

Atropine↗
PubMedDate not supplied

Autoradiographic distribution of 125I-VIP binding in the rat adrenal cortex.

Using in vitro autoradiography, 125I-VIP binding was found to be concentrated in the capsule and glomerulosa of the rat adrenal cortex. The densest receptor distribution was coincident with the distribution of VIP nerve fibers that arborize extensively in the capsule and glomerulosa. The specificity of this binding was demonstrated using unlabelled VIP, ACTH and angiotensin II. The presence and distribution of 125I-VIP binding sites provides the link between the previously found VIP nerves and the steroidogenic effect of exogenous VIP, thereby substantiating the physiological role of VIP-containing autonomic nerves in the regulation of adrenocortical cell function.

Adrenal Cortex↗