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Biomedical subjects

E A Armstrong

Publications and source records attributed to E A Armstrong.

12 recordsLinked to original sources
PubMed2001

Prolonged seizures exacerbate perinatal hypoxic-ischemic brain damage.

This study was undertaken to clarify whether seizures in the newborn cause damage to the healthy brain and, more specifically, to determine the extent to which seizures may contribute to the brain-damaging effects of hypoxia-ischemia (HI). Seizures were induced in 10-d-old rat pups with kainic acid (KA). Seizure duration was determined electrographically. HI was induced by common carotid artery ligation followed by exposure to 8% oxygen for either 15 or 30 min. Six groups of animals were assessed: 1) controls [neither KA nor HI (group I)]; 2) group II, KA alone; 3) group III, 15 min HI alone; 4) group IV,15 min HI plus KA; 5) group V, 30 min HI alone; and 6) group VI, 30 min HI plus KA. Animals were assessed neuropathologically at 3 (early) and 20 (late) d of recovery. KA injection without hypoxia resulted in continuous clinical and electrographic seizures lasting a mean of 282 min. No neuropathologic injury was seen in groups I (no HI or KA), II (KA alone), III (15 min HI alone), or IV (15 min HI and KA). Animals in group V (30 min HI alone) displayed brain damage with a mean score of 2.3 and 0.60 at 3 and 20 d of recovery, respectively. Animals in group VI (30 min HI and KA) had a mean score of 12.1 and 3.65 at 3 and 20 d of recovery, respectively. Compared with group V, the increased damage as a result of the seizure activity in group VI occurred exclusively in the hippocampus. Status epilepticus in the otherwise "healthy" neonatal brain does not cause neuropathologic injury. However, seizures superimposed on HI significantly exacerbate brain injury in a topographically specific manner.

Animals↗
PubMed1999

A phosphatidylinositol 3-kinase-dependent pathway that differentially regulates c-Raf and A-Raf.

Cytokines trigger the rapid assembly of multimolecular signaling complexes that direct the activation of downstream protein kinase cascades. Two protein kinases that have been linked to growth factor-regulated proliferation and survival are mitogen-activated protein/ERK kinase (MEK) and its downstream target Erk, a member of the mitogen-activated protein kinase family. Using complementary pharmacological and genetic approaches, we demonstrate that MEK and Erk activation requires a phosphatidylinositol 3-kinase (PI3-K)-generated signal in an interleukin (IL)-3-dependent myeloid progenitor cell line. Analysis of the upstream pathway leading to MEK activation revealed that inhibition of PI3-K did not block c-Raf activation, whereas MEK activation was effectively blocked under these conditions. Furthermore, agents that elevated cAMP suppressed IL-3-induced c-Raf activation but did not inhibit MEK activation. Because c-Raf activation and MEK activation were inversely affected by PI3-K- and cAMP-dependent pathways, we examined whether IL-3 activated the alternative Raf isoforms A-Raf and B-Raf. Although IL-3 did not activate B-Raf, A-Raf was activated by the cytokine. Moreover, A-Raf activation, like MEK activation, was blocked by inhibition of PI3-K but was insensitive to cAMP. Experiments with dominant negative mutants of the Raf isoforms showed that overexpression of dominant negative c-Raf did not prevent MEK activation. However, dominant negative A-Raf effectively blocked MEK activation, suggesting that activation of the MEK-Erk signaling cascade is mediated through A-Raf. Taken together, these results suggest that IL-3 receptors engage and activate both c-Raf and A-Raf in hemopoietic cells. However, these intermediates are differentially regulated by upstream signaling cascades and selectively coupled to downstream signaling pathways.

Androstadienes↗
PubMed1993

Role of cations and IgA in saliva-mediated aggregation of Pseudomonas aeruginosa in cystic fibrosis patients.

Oral colonization by Pseudomonas aeruginosa possibly precedes the pulmonary infection process in cystic fibrosis (CF) patients. As bacterial aggregates may play a role in establishment of pulmonary infections, involvement of IgA and cations in CF patient saliva-mediated aggregation of P. aeruginosa was investigated. For colonized patients, P. aeruginosa aggregation correlated with bacterial-specific and total salivary IgA. Cation or IgA depletion reduced P. aeruginosa aggregation by saliva from all patients. However, if cations were removed before IgA, and saliva was then reconstituted with calcium, only colonized patient saliva showed reduced aggregation. Aggregation by IgA-depleted saliva was augmented by reconstituting with original IgA. CF patient saliva-mediated aggregation of P. aeruginosa thus is cation-dependent and enhanced by bacterial-specific IgA. Characterizing the interactions among bacterial aggregating factor(s), cations, and antibodies in CF saliva will help clarify the link between P. aeruginosa oral colonization and pulmonary infections in CF patients.

Adolescent↗
PubMed1986

Renal cystic disease in childhood.

The authors present a comprehensive review of the diagnostic features of eight forms of renal cystic disease that occur in childhood. Sonographic findings are emphasized.

Child↗
PubMed1982

CT of neuroblastomas and ganglioneuromas in children.

Computed tomography (CT) has made a profound impact on the diagnosis and treatment of neuroblastomas and ganglioneuromas. The size, location, calcification, composition, and contiguous spread of the tumors has been well demonstrated by CT. CT is essential for their staging, subsequent treatment, and follow-up. Seventy-seven children were reviewed, 67 with neuroblastoma and 10 with ganglioneuroma seen between 1976 and 1980. Fifty-eight had one or more body CT scans, 22 had metrizamide myelography and/or CT metrizamide myelography, and three patients had cranial CT. Intraspinal extension of tumor occurred in 11 instances, several requiring decompressive surgery. A workup plan for optimal use of CT and CT metrizamide myelography was developed from this experience.

Adolescent↗
PubMed1980

Intussusception complicated by distal perforation of the colon.

Three cases of perforation of the colon distal to an ileocolic intussusception are presented. Two cases were associated with attempted hydrostatic reduction of the intussusception, while the other was discovered at operation. The mechanism of this complication is not clear. When performing a contrast enhanced examination of the colon and there is a risk of perforation: (a) dilute water-soluble contrast medium should be used; (b) special attention should be paid to the colon distal to the intussusception; and (c) should contrast material be observed in the peritoneal cavity, the enema reservoir should immediately be lowered to the floor to siphon off the liquid from the colon.

Barium Sulfate↗
PubMedDate not supplied

Long-term gastrostomy in children: caregiver coping.

As technologic interventions such as long-term gastrostomy in children with severe disability become commonplace, and increasing numbers of medically complex children are cared for in the home, nurses will require specialized knowledge to support families. In this article, the authors document findings from a longitudinal study of families caring for a child with a gastrostomy, specifically addressing the caregiver perspective on how families cope with this challenge. The findings reveal a complex set of effective coping strategies as articulated by family caregivers experienced in the management of long-term gastrostomy. Further, these caregivers reveal insights about gastrostomy's technical, social, and psychologic implications for both themselves and their children. In documenting an insider perspective on this phenomenon, this study provides nurses with a comprehensive orientation to the ways in which healthcare professionals can better support family caregiver coping.

Adaptation, Psychological↗
PubMedDate not supplied

Benign suprasellar cysts: the CT approach.

Preoperative diagnosis of intracranial cysts has been simplified and made more rapid and accurate with computed tomography (CT). By means of conventional CT and CT metrizamide ventriculography, the position and communication of intracranial cysts with the ventricular system and subarachnoid space or cisterns can be demonstrated. Suprasellar arachnoid cysts can produce significant neurologic and endocrinologic abnormalities due to their position. They are a surgically curable cause of hydrocephalus. Preoperative differentiation from aqueduct stenosis or other causes of a large third ventricle is important. The usefulness of coronal CT and CT metrizamide ventriculography in the investigation of these lesions is illustrated in six patients.

Cerebral Ventriculography↗