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Biomedical subjects

Andrew Butler

Publications and source records attributed to Andrew Butler.

11 recordsLinked to original sources
PubMed2006

DFTMP, an NMR reagent for assessing the near-neutral pH of biological samples.

A new NMR chemical shift standard and pH indicator, difluorotrimethylsilanylphosphonic acid (DFTMP), is described, and the utility of this reagent is demonstrated for in situ determination of pH in complex biofluids. The pH dependence of this reagent allows accurate in situ determination of aqueous solution pH to within an RMSE of 0.02 pH units over a pH range of 5 to 8. Advantages of this reagent over previously described pH-sensitive components include (1) lack of metal binding affinity, (2) minimal disturbance of endogenous spectral regions, and (3) the potential to function as a multinuclear pH indicator and chemical shift reference point for 19F, 1H, and 31P nuclei. This reagent will be generally useful for NMR experiments on biological systems where the pH needs to be accurately measured at the moment of data acquisition.

Animals↗
PubMed2006

Attempting to improve function and quality of life using the FTM Protocol: case report.

BACKGROUND AND PURPOSE: The Functional Tone Management (FTM) arm training program uses repetitive task practice, stretching, and electrical stimulation as patients with moderate upper extremity hemiparesis wear a dynamic hand orthosis to retrain grasp and release of objects. The case study quantitatively evaluates the extent to which FTM training improved function and quality of life in a patient who met criteria for which the device was intended. CASE DESCRIPTION: The participant, a 44-year-old male in the chronic stage of stroke recovery with moderate right upper extremity motor impairment, was trained for 10 days over a 2-week period by a licensed clinician with extensive experience in FTM training methods. Measurements were taken over 3 baseline visits, then immediately preintervention, postintervention, and at a 3-month follow-up. The outcome measures, following the International Classification of Functioning, Disability, and Health (ICF) Model, included the: Fugl-Meyer assessment (FMA) (upper extremity portion), UE range of motion (ROM), Modified Ashworth scale, Wolf Motor Function Test (WMFT), and the Motor Activity Log (MAL). Health related quality of life was measured using the Stroke Impact Scale (SIS). OUTCOMES: The participant showed limited gains in upper extremity function immediately postintervention. Increases in AROM occurred in forearm supination and wrist flexion and extension, but no improvements were noted in finger ROM. A slight decrease in tone was found in forearm pronators (1 to 0) and wrist flexors (1+ to 1). WMFT values for the more affected upper extremity did not change immediately after training, but a 17% reduction in time occurred at follow-up, with improvements, most notably in the tasks of lifting a pencil and lifting a paper clip. No changes occurred in UE-FMA scores immediately following the intervention, however, a 17% improvement was measured at followup. A slight improvement in MAL scores was noted but not to a level of independent functional use of the impaired upper extremity. SIS scores improved in the domains of strength, communication, mobility, social participation, hand recovery, and overall physical component, while decreases were seen in the ADL/IADL, hand function, emotion, and cognitive domains. DISCUSSION: The case study indicates that for this patient with chronic, moderate upper extremity impairment following stroke, a 2-week FTM training regimen resulted in modest changes occurring as a decrease in impairment, with functional improvement and improved quality of life. Further investigation of the innovative training program should be undertaken before the efficacy of its use can be ascertained amongst patients with limitations comparable to the participant.

Adult↗
PubMed2006

Subjective assessment of a new moisturizing mouthwash for the symptomatic management of dry mouth.

OBJECTIVE: A randomized clinical trial and consumer usage test were conducted to evaluate the acceptability and benefits of OASIS Moisturizing Mouthwash in subjects experiencing symptoms of dry mouth. METHODOLOGY: Study 1: A randomized, double blind, two-period crossover clinical trial was conducted in 49 subjects to evaluate OASIS Moisturizing Mouthwash and an experimental mouthwash formulation. Following a three-day acclimatization phase, subjects used both products at home for three days. Each treatment phase was separated by a three-day washout period. Study 2: Subjects participated in a one- to two-week home usage consumer test using OASIS Moisturizing Mouthwash, after which they completed a 52-question online survey exploring sensory benefits and resultant quality of life attributes of the product. RESULTS: Study 1: A total of 46 adults with a mean age of 64 years completed the study. On average, subjects used the test products three times per day. OASIS Moisturizing Mouthwash was found to be beneficial in managing dry mouth, and was well-liked by the study population, as evidenced by a statistically significant improvement over subjects' normal remedies for managing dry mouth for strength of flavor, taste, freshening breath, immediate and long lasting lubrication, and moisturization. Both products were well-tolerated. Study 2: Three-hundred and twenty-three subjects completed a one- to two-week consumer home usage test followed by an online questionnaire. On a five-point scale, over 80% of respondents perceived the OASIS Moisturizing Mouthwash as "excellent" or "very good" on sensory attributes such as taste and texture, and 70-80% gave the product an "excellent" or "very good" rating on benefit attributes. CONCLUSION: These studies showed that OASIS Moisturizing Mouthwash was beneficial in managing dry mouth, and was well-liked by the study population.

Adolescent↗
PubMed2003

Mirror apraxia affects the peripersonal mirror space. A combined lesion and cerebral activation study.

Mirror apraxia is a condition in which patients with lesions of the posterior parietal cortex have deficits in reaching to objects presented through a mirror. The aim of the present study was to investigate possible mechanisms underlying this disorder. First, we addressed the question of whether mirror apraxia is exhibited to the same extent in peripersonal and in body space. Four patients with lesions of the posterior parietal lobe on either side and with marked mirror apraxia were required to reach for objects that were presented to them through a mirror and located either in body space (i.e. on the body surface) or in peripersonal space (i.e. in the reaching distance). Whereas reaching for objects located in body space was flawless in all patients, the performance deteriorated when the same objects were transferred to the peripersonal space. Although the objects were located only a few centimetres above the body surface, the patients reached towards the virtual object in the mirror. Based on these results we suggest that mirror apraxia may originate from a dissociation between the representations of body schema and peripersonal space and that objects located on the body surface become integrated into the body schema. In the second part of the study, using positron emission tomography study (PET), we studied the cerebral activation pattern during reaching to objects presented through a mirror in the peripersonal space in healthy subjects. The results show that increased neural activity in the anterior part of the intraparietal sulcus and in the dorsal premotor cortex was bound to the transformation of the target position from the mirror space to the real space. In contrast, the activity related to object localization in the mirror occurred at the parieto-occipital junction. Both mirror and arm transformation involved the medial posterior part of the superior parietal lobule, putatively area V6a. The results demonstrate that acting through a mirror is processed in a number of cortical areas of the dorsal stream.

Aged↗
PubMed2003

The effect of dehydroepiandrosterone (DHEA) on recognition memory decision processes and discrimination in postmenopausal women.

In this article, the theoretical distinction between recognition memory decision and discrimination processes is used to explore the effect of dehydroepiandrosterone (DHEA) in postmenopausal women. DHEA is an adrenal steroid that diminishes with aging. It has enhanced memory in laboratory animals. An 8-week placebo-controlled, double-blind experiment in which 30 women (ages 39-70) received a 50-mg/day oral dose of DHEA for 4 weeks demonstrated that DHEA made subjects more conservative (i.e., less likely to call test items "old") in their recognition memory decisions and enhanced recognition memory discrimination for items presented briefly. The former result may reflect an empirical regularity (Hirshman, 1995) in which recent strong memory experiences make participants more conservative. The latter result may reflect the effect of DHEA on visual perception, with consequent effects on memory. These results suggest the methodological importance of focusing on decision processes when examining the effects of hormones on memory.

Administration, Oral↗
PubMed2002

Advantages of normothermic perfusion over cold storage in liver preservation.

BACKGROUND: To minimize the ischemia-reperfusion injury that occurs to the liver with the current method of preservation and transplantation, we have used an extracorporeal circuit to preserve the liver with normothermic, oxygenated, sanguineous perfusion. In this study, we directly compared preservation by the standard method of simple cold storage in University of Wisconsin (UW) solution with preservation by perfusion. METHODS: Porcine livers were harvested from large white sows weighing between 30 and 50 kg by the standard procedure for human retrieval. The livers were preserved for 24 hr by either cold storage in UW solution (n=5) or by perfusion with oxygenated autologous blood at body temperature (n=5). The extracorporeal circuit used included a centrifugal pump, heat exchanger, and oxygenator. Both groups were then tested on the circuit for a 24 hr reperfusion phase, analyzing synthetic function, metabolic capacity, hemodynamics, markers of hepatocyte and reperfusion injury, and histology. RESULTS: Livers preserved with normothermic perfusion were significantly superior (P=0.05) to cold-stored livers in terms of bile production, factor V production, glucose metabolism, and galactose clearance. Cold-stored livers showed significantly higher levels of hepatocellular enzymes in the perfusate and were found to have significantly more damage by a blinded histological scoring system. CONCLUSIONS: Normothermic sanguineous oxygenated perfusion is a superior method of preservation compared with simple cold storage in UW solution. In addition, perfusion allows the possibility to assess viability of the graft before transplantation.

Animals↗
PubMed2002

Optimisation of bile production during normothermic preservation of porcine livers.

Machine perfusion of livers may provide a mechanism for extended preservation of marginal donor organs before transplantation, as well as a method for viability assessment. It has proved possible in a series of experimental porcine liver perfusions to maintain liver viability for up to 72 h. However, a reduction in bile production with associated histological evidence of cholestasis was seen after 10 h of perfusion, damaging the biliary canaliculi during the preservation period and leaving these organs in an unacceptable condition for transplantation. It was proposed that reduction in bile production was the result of a relentless depletion of available bile salts, gut recirculation not being possible and de-novo synthesis being unable to keep up with loss. This was proved by measuring porcine native bile acids within serial perfusate and bile samples using gas chromatography mass spectrophotometry. It was shown that all three native pig bile acids were decreased to 30% of their original value by 20 h of unsupplemented perfusion. An infusion of taurocholate managed to maintain bile production at physiological levels throughout the 20-h period (8 mL/h +/- 0.75). It was successfully incorporated by the porcine livers into bile. We propose to use this circuit as a novel means of preserving donor livers for transplantation in which the organ is maintained at normal body temperature and perfused with blood. This will reduce ischaemia reperfusion injury and may enable prolonged preservation. The modification described ensures optimal bile production over the entire perfusion period, preventing inspissation and subsequent damage to the canaliculus.

Animals↗