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Biomedical subjects

R Nelson

Publications and source records attributed to R Nelson.

At least 361 records · Page 20Linked to original sources

Enzyme-linked immunoassay for respiratory syncytial virus is not predictive of bronchiolitis in sudden infant death syndrome.

Although respiratory syncytial virus (RSV)-infected infants may present with apnea, the role that RSV plays in sudden infant death syndrome (SIDS) is speculative. To determine whether RSV is associated with bronchiolitis in these patients, we examined histologic sections of lungs from 41 apparent SIDS cases and compared the results with those of enzyme-linked immunofluorescent assay (EIA) from nasal washings. Bronchiolitis was defined by a bronchiolar inflammatory cell infiltrate plus epithelial necrosis. A positive EIA was associated with bronchiolitis in 8 instances, compared with 6 having a positive EIA and negative histology, 14 having a negative EIA and positive histology, and 13 having EIA and histology both negative. These results yield a predictive value of a positive test of 57% and a predictive value of a negative test of 48% (P > .9 by chi square analysis). Although RSV of the upper respiratory tract may be related to SIDS, our results indicate that EIA of nasal washings is not predictive of bronchiolitis, and we recommend other means of verification of histologic results.

Antibodies, Viral↗

The gene product of the Plasmodium falciparum 11.1 locus is a protein larger than one megadalton.

The Plasmodium falciparum 11.1 gene locus on chromosome 10 extends over 30 kb and contains approximately 22 kb of a tandemly repeated 27-bp sequence. Biochemical and size similarities have been noted between the reported 11.1 antigen and a variable-Mr, surface-radioiodinatable protein which appears to be involved in the cytoadherence of red blood cells infected with mature intraerythrocytic parasites to venular endothelium. We attempted to determine if these proteins were identical. Using rabbit antibody and affinity purified human immune sera specific for peptides encoded by the 27-bp repeat and a flanking 5' region, we have shown that the 11.1 locus encodes a protein of more than 1000 kDa. This protein cross-reacts with an uncharacterized 260-kDa protein, previously identified as the gene product of the 11.1 locus, and Pf155-RESA, but not with the radioiodinatable protein. The 11.1 protein that we have identified is a malarial protein of unprecedented size.

Animals↗

Aspiration in patients with head and neck cancer and tracheostomy.

Tracheopulmonary aspiration is a common occurrence in patients with dysphagia associated with head and neck cancer. We performed quantitative scintigraphic analysis of tracheopulmonary aspiration in 125 patients with head and neck cancer; 58 of these patients had a tracheostomy. Tracheopulmonary aspiration occurred in 58% of patients with a tracheostomy and in 23% of patients without a tracheostomy. In six of seven patients with a tracheostomy, tracheopulmonary aspiration significantly increased when the obturator was removed and, in these patients, occlusion of the tracheostomy tube during feedings eliminated or reduced the complication. Our studies suggest that aspiration can be monitored accurately and conveniently by scintigraphy, and that this technique is useful in the evaluation and management of dysphagia in debilitated patients.

Adult↗

Effectiveness of adjunct therapies in crack cocaine treatment.

Although intensive outpatient therapy is recommended for treatment of cocaine, psychosocial characteristics associated with crack cocaine abuse are also implicated in attrition from outpatient programs. Acupuncture, medications, and brainwave therapy (biofeedback), have all been used to encourage treatment retention and drug use outcomes. The effectiveness of three adjunct therapies in improving retention and drug use outcomes in intensive outpatient cocaine treatment was tested in a primarily young, indigent African-American sample of crack cocaine users at a community hospital in a low-income, high drug use neighborhood in Houston. Subjects were assigned to receive either neurobehavioral treatment alone or neurobehavioral with one of three adjunct therapies. These included acupuncture, anticraving medication, or brainwave therapy. Comparative results indicated that dosage of any adjunct therapy was associated with days in treatment and standard treatment sessions attended, and that standard treatment sessions attended was associated with negative urinalysis results at follow-up. None of the adjunct therapies were directly associated with drug use outcomes.

Acupuncture Therapy↗

Selective stimulatory actions of corticotropin-releasing factor ligands on correlates of energy balance.

Acute administration of corticotropin-releasing factor (CRF) results in anorexic and sympathomimetic effects that suggest efficacy in chronic models of energy balance. The present studies employed a broad spectrum energy balance indices in lean and genetically obese Zucker rats in order to fully characterize the pharmacological efficacy of CRF and a CRF binding protein (CRF-BP) ligand inhibitor, CRF(6-33), which is thought to liberate CRF from CRF-BP. Acute administration of CRF(6-33) significantly increased CRF(2) receptor density by 10% within the ventromedial hypothalamic (VMH) nucleus of Zucker lean rats and decreased density by 10% in Zucker obese rats. A single infusion of CRF(6-33) increased nonshivering thermogenesis by 25-30% as measured by proton conductance in brown adipose tissue of both lean and obese rats. Chronic CRF(6-33) infusion suppressed body weight gain and elevated core temperature irrespective of genotype while increasing motor activity in obese rats without altering heart rate or blood pressure. Taken together, these results document strain-dependent, long-term effects of a CRF-BP ligand inhibitor on a select subset of physiological and behavioral measures of increased energy expenditure.

Adipose Tissue, Brown↗

The trajectory of client progress. A longitudinal pilot study.

Successful nonchemical drug treatment is a transformative experience: client change is the goal of treatment. Two domains in which programs intend to facilitate change are emotional well-being and the therapeutic relationship. Little previous research has addressed the question of what changes clients in drug treatment actually undergo while in treatment. This article presents results from a pilot longitudinal study of clients in two short-term drug treatment programs in Houston, TX. Results showed measurable increases in self-esteem and connection to counselor and decreases in anxiety and depression over the course of treatment for clients who completed treatment. Program graduates and early withdrawals showed distinctly different patterns of progress as measured by emotional and relationship scales.

Adult↗

Sterilization with methyl cyanoacrylate-induced fallopian tube occlusion from a nonsurgical transvaginal approach in rabbits.

PURPOSE: To evaluate a nonsurgical, nonhormonal sterilization procedure performed with use of transvaginal microcatheterization techniques and methyl cyanoacrylate (MCA) as a sclerosing agent MATERIALS AND METHODS: Seventeen adult virgin female rabbits underwent bilateral fallopian tube cannulation through a nonsurgical transvaginal approach with use of a coaxial catheter system with fluoroscopic guidance. Fourteen of the rabbits underwent bilateral fallopian tube occlusion with direct MCA injection; the remaining three rabbits were separated as controls. Three of the rabbits with occlusions were killed as temporal histologic controls. The remaining 11 rabbits with occlusions and the initial three controls underwent 6 months of mating trials. All 17 rabbits were killed. Gross inspection was performed and histologic specimens of their fallopian tubes were obtained. RESULTS: None of the 11 rabbits with occlusions that underwent mating became pregnant. All three control rabbits became pregnant. Histologic examination of the occluded fallopian tubes demonstrated long-segment tubal wall fibrosis with varying degrees of occlusion. No peritoneal abnormalities were identified. Histologic findings for the three control animals were normal. CONCLUSION: With use of a nonsurgical transcervical coaxial catheter system, MCA can be placed directly into fallopian tubes without difficulty. MCA administration leads to fallopian tube fibrosis and occlusion. A 100% nonpregnancy rate was demonstrated. Further investigation may lead to a safer, more convenient, and less expensive form of permanent sterilization.

Animals↗

Conductances evoked by light in the ON-beta ganglion cell of cat retina.

When a bar of light (215 x 5000 microns) illuminates the receptive field of an ON-beta ganglion cell of cat retina, the cell depolarizes. Intracellular recording from the cat eyecup preparation shows that this depolarization is due to an increase in conductance (2.4 +/- 0.6 nS). Different phases of this depolarization have different reversal potentials, but all of these reversal potentials are more positive than the cell's resting potential in the dark. When the light is turned on, there is an initial transient depolarization; the reversal potential measured for this transient is positive (23 +/- 11 mV). As the light is left on, the cell partially repolarizes to a sustained depolarization; the reversal potential measured for this sustained depolarization is close to zero (-1 +/- 5 mV). When the light is turned off, the cell repolarizes further; the reversal potential measured for this repolarization is negative (-18 +/- 7 mV), but still above the resting potential in the dark (-50 mV). To explain this variety of reversal potentials, at least two different synaptic conductances are required: one to ions which have a positive reversal potential and another to ions which have a negative reversal potential. Comparing the responses to broad and narrow bars suggests that these two conductances are associated with the center and surround, respectively. Finally, since an ON-beta cell in the area centralis receives about 200 synapses, these results indicate that a single synapse produces an average conductance increase of about 15 pS during a near-maximal depolarization.

Animals↗

Functional role of GABA in cat retina: I. Effects of GABAA agonists.

Putative GABAergic mechanisms were studied in perfused cat retina by means of intracellular recording and application of GABA and the GABAA agonists delta-amino valeric acid (dAVA), muscimol, and THIP. In contrast to results reported previously for cold-blooded vertebrates, introduction of 20 mM GABA into the superfusate had no influence upon the response properties of cat retinal horizontal cells (HCs). In common with results reported in cold-blooded vertebrates, introduction of the GABAA agonists dAVA (2-12 mM) and THIP or muscimol (0.2-1 mM) had four consistent reversible influences upon the response properties of cat retinal HCs: (1) they reduced photic-response amplitude, (2) slowed response onset, (3) slowed response offset, and (4) depolarized the dark membrane potential. Both rod and cone signal components were affected. GABAA agonists had similar influences upon both the time course and amplitude of responses recorded from amacrine and ganglion cells. In all cell types examined, the influence upon response kinetics was made particularly apparent with rapidly flickering stimuli. Flicker responses were reduced in amplitude much more than sustained responses. These results suggest that, in addition to other influences, GABAergic action serves to modify the time course of photic responses in both the inner and outer plexiform layer of mammalian retina making responses slower and less phasic.

Animals↗

Functional role of GABA in cat retina: II. Effects of GABAA antagonists.

Putative GABAergic mechanisms were studied in the cat retina by exogenous application of the GABAA antagonists picrotoxin (PTX), native bicuculline (BCC), and bicuculline methyl bromide (BCC MeBr). When recording intracellular responses from horizontal cells (HCs) and amacrine cells as well as electroretinograms (ERGs), drugs were added to the perfusate used to maintain the isolated eyecup; when recording extracellular spikes from ganglion cells of anesthetized cats, drugs were introduced by iontophoretic injection. Both PTX and BCC MeBr had relatively little influence upon the response properties of HCs. In contrast, native BCC tended to decrease the amplitude of and to slow the photic response to light onset and both to quicken and to increase the amplitude of response to light offset; in the presence of native BCC, HC responses were dominated by a prominent spike-like "Off-overshoot." The influence of GABAA agonists upon HC responses was not blocked by GABAA antagonists. ERG b-wave amplitude was reduced both by PTX and by native BCC, but was not influenced by BCC MeBr. Latency (time to half-peak) was increased by low doses of native BCC, and to a lesser extent PTX but not BCC MeBr. Rod-amacrine On-transient responses were increased in amplitude by PTX. Extracellular recordings from On- and Off- X and Y ganglion cell types became considerably more transient with application of either PTX, native BCC, or BCC MeBr; this tendency was greater in Off-type ganglion cells. Collectively, these results strengthen conclusions from the previous paper suggesting that GABA serves to slow onset and offset kinetics of retinal neurons, making them more sustained and less phasic. They also suggest that in mammalian retina heterogeneous types of GABAA receptors exist, segregated into different zones: a distal zone, sensitive only to native BCC, a central zone sensitive to both native BCC and PTX, and a proximal zone sensitive to native BCC, BCC methyl halides (BCC MeH), and PTX. Only the proximal zone obeys conventional GABAA pharmacology.

Animals↗

Distribution of GABA(C)-like responses among acutely dissociated rat retinal neurons.

GABAergic responses of acutely dissociated rat retinal neurons, including both bipolar cells (BCs) and other, morphologically round cells (RCs), were assayed with the fluorescent (FL), voltage-sensitive probe oxonol DiBaC4(5). Using intensified video microscopy and simultaneous recording, GABA responses were identified in one-third of cells in a typical microscope field; of these 85% hyperpolarized (0.05-0.3 log unit FL decreases) while the remainder depolarized (0.05-0.2 log unit FL increases). GABA-sensitive cells were also TACA-sensitive (trans-4-Aminocrotonic acid), and these ligands appeared interchangeable in ability to evoke responses. In RCs, an asymmetric co-responsive pattern was observed between GABA- and muscimol-evoked events. Muscimol-sensitive RCs responded well to GABA, but not all GABA-sensitive RCs responded to muscimol. In GABA-sensitive BCs, muscimol responses were typically weak or absent. Few BCs or RCs responded to CACA (cis-4-Aminocrotonic acid). Bicuculline-resistant GABA responses occurred in approximately 80% of GABA-responsive RCs and BCs. Both bicuculline-sensitive (GABA(A)-like) and bicuculline-insensitive (GABAc-like) responses were resistant to picrotoxin. Although a small minority of GABA-sensitive cells hyperpolarized in response to R(+)baclofen, bicuculline-insensitive responses were not antagonized by 2-hydroxysaclofen, and were abolished in low [Cl-]o. Results suggested (1) that bicuculline-insensitive, Cl(-)-dependent, GABAc-like responses were broadly distributed and predominant among dissociated rat retinal neurons; (2) that muscimol was a particularly weak agonist for rat retinal BCs; and (3) that oxonol was a sensitive probe for retinal GABA responses.

Animals↗

Acute care functional assessment begins at the bedside.

Patient functional ability is a determining factor in successful discharge and self-care. A model for improving the use of functional assessment in the acute care setting gives the bedside registered nurse a tool to manage care.

Activities of Daily Living↗

A pilot study of client progress in short-term drug abuse treatment.

This paper is a pilot study of client progress in two short-term (23-day) drug abuse treatment programs. Client progress is defined as those changes in cognitive functioning, emotional well-being, and social support resources that are th proximate goals of drug abuse treatment. In this study, client progress was measured by changes in cognitive functioning, emotional well-being, and social support domains over the course of treatment. This pilot study showed that client progress can be detected in short-term treatment and can be related to indicators of the quantity and quality of treatment. In general, results showed that both relationships and emotional well-being changed over the course of treatment. Cognitive functioning variables did not generally change over time, nor were they related to indicators of treatment quality. Evidence in this pilot study suggests that more attention needs to be given to the relational and emotional aspects of the drug abuse treatment process.

Adolescent↗

Milk feeding and changes in intestinal permeability and morphology in the newborn.

The contrasting effects of natural versus cow's milk formula (CMF) on upper gastrointestinal development in the newborn were studied. The passive intestinal permeability of neonatal human infants and guinea pigs was measured using the nonmetabolisable markers lactulose and mannitol. Mucosal morphology was examined in guinea pigs by light microscopy. Nineteen full-term human infants and 63 guinea pigs were studied during the 1st week of extrauterine life. The naturally fed infants showed a decline in intestinal permeability to lactulose following the onset of feeding. This was not shared by those fed CMF. The CMF-fed guinea pigs showed a persistently higher intestinal permeability than the naturally fed animals throughout the 1st week of life. No differences were observed in the villous heights or crypt depths between feeding groups, but both showed an increase in intraepithelial lymphocyte number during the 1st week. Cow's milk formula may cause a persistently higher intestinal permeability, or natural feeding may promote a decline in permeability in the enterally fed newborn.

Animals↗

Musculoskeletal dysfunction of the neck in migraine and tension headache.

In this prospective controlled study, thirty-seven migraine and/or tension headache patients and thirty-seven age and sex matched controls were examined for evidence of musculoskeletal dysfunction in the neck. The examination consisted of clinical range of motion testing of neck rotation, sidebending, flexion and extension while in the sitting position. The headache group had more abnormal physical findings than the control group. Although the difference for each particular motion test, taken by itself, was not statistically significant, two or more abnormalities in combination was found to reach a .05 confidence level of significance. It is proposed therefore that musculoskeletal dysfunction of the neck is a contributing factor to the etiology of migraine and tension headache.

Adolescent↗

Crow deaths as a sentinel surveillance system for West Nile virus in the northeastern United States, 1999.

In addition to human encephalitis and meningitis cases, the West Nile (WN) virus outbreak in the summer and fall of 1999 in New York State resulted in bird deaths in New York, New Jersey, and Connecticut. From August to December 1999, 295 dead birds were laboratory-confirmed with WN virus infection; 262 (89%) were American Crows (Corvus brachyrhynchos). The New York State Department of Health received reports of 17,339 dead birds, including 5,697 (33%) crows; in Connecticut 1,040 dead crows were reported. Bird deaths were critical in identifying WN virus as the cause of the human outbreak and defining its geographic and temporal limits. If established before a WN virus outbreak, a surveillance system based on bird deaths may provide a sensitive method of detecting WN virus.

Animals↗