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Biomedical subjects

S Rogers

Publications and source records attributed to S Rogers.

At least 109 records · Page 6Linked to original sources
PubMed1997

Experience-dependent changes in the number of chemosensory sensilla on the mouthparts and antennae of

The effect of diet on the number of gustatory and olfactory sensilla was investigated in locusts. Insects fed for the final two stadia on nutritionally adequate synthetic foods have fewer sensilla on the maxillary palps and antennae than insects fed on the usual rearing diet of seedling wheat. This effect was seen irrespective of the nutritional balance of the foods and was independent of the concentration of nutrients present or the size of the insect. Supplying wheat odour to locusts fed synthetic foods had no effect on the number of sensilla present on the palps, but completely reversed the decrease in the number of olfactory sensilla of the antennae and partially reversed the decrease in the number of antennal uniporous trichoid sensilla. Locusts that were allowed to select between two nutritionally unbalanced but complementary synthetic foods had a higher number of sensilla on the maxillary palps than those fed individual synthetic foods, providing the two foods differed substantially in their protein:carbohydrate ratios. Insects also developed more sensilla if they were fed on two foods of identical nutritional composition but with different added flavours (1% tannic acid or amygdalin). Exposing locusts to synthetic foods for a single stadium did not cause any significant decrease in sensilla number. The results suggest that the number of sensilla that develop in a given sensory field is influenced by the variety of chemical stimuli experienced and the chemical complexity of the environment as provided by the presence of distinct individual sources of stimulation.

Journal Article↗
PubMed1997

The five Cs of choice. Outcome measures for individuals with severe and persistent mental illness.

In a time when mental health service providers are cutting costs and services, stakeholders need adequate information in the form of outcome measures to evaluate services based on quality. Outcome measures are particularly important for high-risk populations, where severe and persistent mental illness results in serious functional impairment of daily life. A client-oriented method of gauging rehabilitation of real-world behavior over the long-term, as well as the short-term, and which allows for comparison with other programs, must be developed. Lack of agreement on the domains to be measured, however, has hindered the development of common standards, making it difficult to track accountability and service effectiveness. Four authors provide a framework to help organizations choose and develop appropriate outcome measures, as well as core data suggested to measure longitudinal changes in rehabilitation.

Chronic Disease↗
PubMed1997

Treatment of psoriasis with intermittent short course cyclosporin (Neoral). A multicentre study.

A 1 year, prospective multicentre study was performed to investigate the efficacy and safety of intermittent treatment with cyclosporin in psoriasis vulgaris. Subjects received cyclosporin (Neoral) 5 mg/kg per day until achieving 90% reduction in area affected, or for a maximum of 12 weeks. Those failing to demonstrate a satisfactory response were withdrawn. When further treatment was required, cyclosporin was recommenced. This cycle was repeated up to three times. Psoriasis activity was recorded using the area affected and sign scores for erythema, scaling and infiltration. Overall assessments of response and tolerability were recorded. Forty-one subjects, mean age 36, mean PASI 12.8, entered the first treatment period. Thirty-three received a second period of treatment and 16 a third. Eighteen failed to complete the study as planned: five were withdrawn due to adverse events, four due to treatment failure and nine due to protocol violations. At the end of each treatment period, significant improvements were seen in all efficacy parameters. Overall response was graded as 'considerable improvement' or 'minimal or no symptoms', by over 80% of subjects and investigators. Median intervals to relapse for subjects remaining in the study were 72 days (range 28-329) and 53 days (range 14-141) after periods 1 and 2, respectively. There were significant increases in mean serum creatinine and blood pressure during each treatment period. However, there were no significant differences in either parameter between baseline and the final follow-up visit. At the end of each treatment period, overall tolerability of the treatment was considered 'good' or 'very good' by over 80% of subjects and investigators.

Adult↗
PubMed1997

Clinical global measures of dementia. Position paper from the International Working Group on Harmonization of Dementia Drug Guidelines.

Following is the report of the committee working on clinical global measures for antidementia drug guidelines. The concepts involved in global scales, the distinctions between change and severity scales, advantages and disadvantages of structured interviews, and anchoring of change scores are discussed, and selected existing clinical global scales are described. In addition, the committee assessed the utility of global scales in clinical trials for antidementia drugs. There was a consensus among the members of the working group on the following: (1) Clinical global scales are interview based; in most cases, they include information obtained from caregivers as well as directly from patients, but they can rely on information from the subject only. (2) Clinicians' global ratings are intended to assess clinically meaningful change based on multidimensional clinical assessment and take into account the clinical heterogeneity of dementia by assessing at least cognition, behavior, and functioning. (3) There are two distinct types of clinical global measures: (a) clinicians' interview-based global severity scales, which generally incorporate classification by stage or severity of illness and (b) clinicians' interview-based global change scales, which incorporate global assessment ratings of clinical change. The committee could not reach a consensus on whether global scales should be required in phase II and phase III clinical trials, or whether other specific assessments such as well-designed activities of daily living, cognition, and behavior measures could, when used in appropriate combinations, replace the global as assessments of clinical meaningfulness.

Activities of Daily Living↗
PubMed1996

Intra-arterial infusion of [125I]A beta 1-40 labels amyloid deposits in the aged primate brain in vivo.

Alzheimer's disease is characterized by extracellular amyloid deposits in the brain at both vascular sites (cerebrovascular amyloid, CVA) and within the neuropil (plaques). In the present study we demonstrated that brain amyloid of aged non-human primates is efficiently detected by [125I]A beta in vitro, and assessed the detection of that amyloid in vivo by intravascular infusion of [125I]A beta. Aged squirrel monkeys (Saimiri sciureus) were anesthetized and infused intra-arterially with [125I]A beta, and sacrificed 2 h later. Analysis of the anterior frontal and temporal cortices by autoradiography demonstrated that [125I]A beta was deposited on CVA and that essentially every amyloid deposit which could be detected with thioflavin S or anti-A beta antibodies was also labeled by [125I]A beta. These experiments suggest that intravascular infusion of radiolabeled A beta can be used to detect and image amyloid deposits in the human AD brain.

Aging↗
PubMed1996

A new animal model for abdominal aortic aneurysms:initial results using a multiple-wire stent.

OBJECTIVES: The effect of a plain 48-wire self-expanding flexible stent (Wallstent-Schneider (Europe) AG) on abdominal aortic aneurysms has been studied in a new animal model. METHODS: Aneurysms were created by interposing fusiform segments of glutaraldehyde-tanned bovine internal jugular vein into the infrarenal aortas of 12 Large White pigs. The first six pigs were assessed after 6 weeks by ultrasonography and arteriography; they were then sacrificed for pathological examination. Endovascular placement of the stents, 2 weeks after aneurysm creation, was performed under arteriographic control in the next six pigs. These pigs were assessed by ultrasonography and arteriography 6 weeks after stenting; they were then sacrificed for pathological examination. RESULTS: At 6 weeks the aneurysms in the first group were pulsatile with partial endothelialisation and no mural thrombus. Placement of the stent in the second group was accomplished easily. Stenting resulted in an immediate reduction in wall pulsatility of all aneurysms and thrombosis of the excluded aneurysm sac occurred in three cases. In the other three cases the pulse pressure in the sac was reduced. In all cases there was a significant reduction in maximum aneurysm diameter when measured 6 weeks after stenting. CONCLUSIONS: A pulsatile, non-thrombogenic aortic aneurysm model approaching human dimensions has been successfully developed for the study of endoprostheses prior to their clinical use. Endovascular placement of a plain, multiple-wire Wallstent was associated with reductions in aneurysm pulsatility, pulse pressure within the sac and maximum aneurysm diameter over the study period. Stenting was associated with thrombosis of the excluded aneurysm sac in 50% of cases.

Animals↗
PubMed1996

Negative intraoral air pressures of deaf children with cochlear implants: physiology, phonology, and treatment.

The primary purpose of this investigation was to examine deaf children's use of negative intraoral air pressures (-Po's) from a physiological and a phonological perspective, with the hope of gathering insight into the strategies these children use to produce speech. A secondary purpose was to compare the effectiveness of two methods of treating these deviant productions. Subjects were four profoundly deaf children, age 6:6-9:2, who used cochlear implants and had demonstrated persistent use of -Po's. Po's were collected during production of CV syllables with initial [p] and [b] and a variety of vowel contexts. Two of the children used -PO's more often before low than high vowels. We suggest that this vowel-based pattern may result when deaf children learn to lower their larynges in response to visible jaw lowering cues. Another child presented with a pattern of more frequent -Po's before front than back vowels, suggesting that she may have expanded her pharynx anteriorly as she attempted to achieve an anterior tongue placement. Two children also clearly used -Po's more frequently for voiced than voiceless stops, possibly resulting from a tendency to use the degree rather than the timing of vocal fold adduction to distinguish voiceless and voiced phonemes. Two of the children were enrolled in a single-subject multiple baseline study to compare the effectiveness of traditional articulation treatment and visual-feedback treatment. The child who was a far less proficient talker demonstrated rapid and sustained change, whereas the better talker demonstrated minimal change with treatment. This study provides evidence that (a) deaf children use speech production strategies quite unlike those of normally hearing children and (b) deviant speech behaviors of deaf children should be treated before they become part of functional phonological systems. This work highlights the need to consider the unique speech behaviors of deaf children, and their reliance on alternate feedback mechanisms, when developing assessment and treatment procedures.

Age of Onset↗
PubMed1996

Nitric oxide synthase inhibition during experimental sepsis improves renal excretory function in the presence of chronically increased atrial natriuretic peptide.

OBJECTIVE: To test whether renal excretory function decreases after nitric oxide synthase inhibition during experimental hyperdynamic sepsis. DESIGN: Prospective, randomized, controlled animal trial. SETTING: Research laboratory at a large university medical center. SUBJECTS: Chronically instrumented Merino breed ewes (n = 18). INTERVENTIONS: Continuous infusion of Escherichia coli endotoxin (10 ng/kg/min) for the experimental period of 32 hrs. One group received a bolus of the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (25 mg/kg), after 24 hrs, and the remaining sheep were given the carrier, sodium chloride 0.9%. MEASUREMENTS AND MAIN RESULTS: The sheep developed a hyperdynamic cardiovascular response characterized by a decrease in systemic vascular resistance index (p < .05), and an increased cardiac index (p < .05) by 24 hrs. The sheep retained fluid, with creatinine clearance decreasing in the presence of chronically increased atrial natriuretic peptide. After the administration of N omega-nitro-L-arginine methyl ester, systemic vascular resistance index and cardiac index returned to baseline values, fluid balance normalized, and glomerular filtration rate increased (p < .05), while the control animals continued to retain fluid and their creatinine clearance continued to decrease. The concentrations of atrial natriuretic peptide did not differ significantly between groups after N omega-nitro-L-arginine methyl ester administration. CONCLUSIONS: In this ovine model of experimental hyperdynamic sepsis, renal excretory function decreases in the presence of chronically increased concentrations of atrial natriuretic peptide. Administration of the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester, reverses the vasodilatory state, thereby improving fluid balance and glomerular filtration.

Animals↗
PubMed1996

Chronic endotoxemia and endothelium-dependent vasodilation in coronary arteries.

Endotoxin acutely decreases the production of nitric oxide, leading to abnormal regulation of coronary vascular tone: however, the effects of chronic endotoxemia on vasomotion are unknown. We therefore tested the hypothesis that chronic, low-level endotoxemia inhibits endothelium-dependent vasodilation. Rabbits were continuously infused with a subclinical dose of Escherichia coli endotoxin (.6 microgram/24 h, intraperitoneal) or saline for 5 wk. Endotoxin at this concentration elicited no significant sustained pyretic or hemodynamic responses. Both endothelium-dependent and independent vasomotor responses were determined in coronary arteries (250-500 mu). Vasorelaxation in response to acetylcholine, but no adenosine diphosphate (ADP), was significantly enhanced in endotoxin-challenged animals (EC50 = 62.6 +/- 11.1 nM, control vs. 33.97 +/- 5.7 nM, endotoxin-challenged; p < .05). Vasoconstriction to PGF2 alpha, but not KCl, was significantly decreased in endotoxin-challenged animals. These results indicate that endothelium-dependent and independent vasomotor responses are altered during chronic endotoxemia and are due, in part, to alterations in signal-transduction mechanisms specific for certain types of receptors.

Acetylcholine↗
PubMed1996

The horizon-ratio relation as information for relative size in pictures.

The horizon-ratio relation was found to be an effective source of information for relative size in pictures under some conditions: when the difference in image size of depicted "same real size" objects was not too great (Experiment 1), and when the horizon line was not too high or too low in the picture (Experiment 2). The latter finding seemed to be linked to the observers' identification of the horizontal line as the horizon (and not as the edge of a finite surface). In addition, individual patterns of response were remarkably systematic even in the absence of a horizon, or any other pictorial information, (Experiment 3). It is suggested that in this case observers imposed a horizon on the picture on which to base their relative size judgments, possibly based on the observer's own eye level or on the content of the picture. It is concluded that although the horizon-ratio relation provides the same kind of information as that available in the optic arrays from real scenes, pictorial information requires the satisfaction of additional constraints in order to be fully effective.

Form Perception↗