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Biomedical subjects

D Wallace

Publications and source records attributed to D Wallace.

At least 37 records · Page 2Linked to original sources
PubMed2001

Non-invasive and quantitative near-infrared haemoglobin spectrometry in the piglet brain during hypoxic stress, using a frequency-domain multidistance instrument.

The frequency-domain multiple-distance (FDMD) method is capable of measuring the absolute absorption and reduced scattering coefficients of optically turbid media. Absolute measurement of absorption at two near-infrared (NIR) wavelengths makes possible the quantitation of tissue haemoglobin concentration and tissue haemoglobin oxygen-saturation (StO2). However, errors are introduced by the uncertainties of background absorption and the dissimilarities between real tissues and the simplified mathematical model on which these measurements are based. An FDMD-based tissue instrument has been used for the monitoring of tissue haemoglobin concentration and oxygenation in the brain of newborn piglets during periods of hypoxia and hyperoxia. These tissue haemoglobin saturation values were compared with arterial saturation (SaO2) and venous saturation (SvO2) measured by blood gas analyses. A linear correlation was observed between StO2 and the average of SaO2 and SvO2. However, StO2 is not equal to any fixed weighted average of SaO2 and SvO2 unless we introduce an effective background tissue absorption. The magnitude of the background absorption was about 0.08 cm(-1) at 758 nm and 0.06 cm(-1) at 830 nm, and it was nearly consistent between piglets. The origin of this 'effective' background absorption may be real, an artefact caused by the application of a simplified model to a complex sample, or a combination of factors.

Animals↗
PubMed2001

Weight gain in a controlled study of risperidone in children, adolescents and adults with mental retardation and autism.

As part of an ongoing, prospective, ABA design, double-blind crossover study of risperidone versus placebo for the treatment of aggressive, destructive and self-injurious behavior in persons aged 6-65 years with mental retardation (MR) and autism, we measured the weight of 19 subjects at each study visit. We compared mean weight gain during the 16-week acute phase and 24-week open maintenance phase with that during the initial and middle placebo phases statistically, using a linear mixed model procedure. Results of the linear mixed model analysis showed that relative weight gain observed during the acute and maintenance drug phases was significantly greater than that observed during the initial and middle placebo phases respectively (p = .0001 and p = .0001). Over approximately a year, children aged 8-12 (n = 5) gained a mean of 8.2 kg (range = 2.7-17.7 kg); adolescents (n = 6) aged 13-16 gained a mean of 8.4 kg (range 3.6-15.5 kg); adults aged 21-51 (n = 8) gained a mean of 5.4 kg (range 0-9.5 kg). Weight gain observed in this controlled study of risperidone treatment in children, adolescents, and adults with MR and autism was significant. It may be greater in this population than in others reported and in this study was not limited to an acute effect only. Rate of weight gain diminished rapidly on tapering and stopping the drug. Further studies are urgently needed, including those incorporating diet and exercise programming.

Adolescent↗
PubMed2001

Quantification of the ultraviolet radiation (UVR) field in the human eye in vivo using novel instrumentation and the potential benefits of UVR blocking hydrogel contact lens.

BACKGROUND/AIMS: Certain degenerative eye conditions occur predominantly nasally, at the limbal region, and are associated with solar ultraviolet radiation (UVR) induced damage. The relative contribution to the in vivo ocular flux of (a) the reflection of UVR incident on the skin of the nose onto the nasal limbus, and (b) the focusing of UVR incident on the temporal side of the cornea onto the nasal limbus were examined. METHODS: A novel photodiode sensor array was used to measure the UVR field across the eye. In addition, a novel spectrometer set-up was used to measure the spectrum of radiation refracted across the cornea. The efficacy of UVR blocking hydrogel contact lenses in filtering incident UVR was assessed in vivo. RESULTS: Qualitative and quantitative data indicated an increase nasally of UVR. Photodiode readings showed a net UVR increase from the temporal to the nasal side. Transmission curves showed that most UVR incident on the limbal region is either absorbed by, or transmitted through, the ocular tissues. This radiation is filtered by UVR blocking soft contact lens. CONCLUSIONS: An increased UVR flux on the nasal side of the eye, due to reflection off the nasal skin, was identified in vivo. Any UVR passing through the cornea is either absorbed by the conjunctiva and/or transmitted through it onto the sclera where it is absorbed. UVR blocking hydrogel contact lenses can eliminate these sources of UVR.

Contact Lenses, Hydrophilic↗
PubMed2001

Spirituality and spiritual care provided by parish nurses.

The high level of religious participation in the United States provides a venue for parish nursing, a holistic nursing specialty that emphasizes the relationship between spirituality and health. This descriptive study measured two aspects of spirituality (spiritual perspective and spiritual well-being) in a national sample of parish nurses and described variables related to their practice. Furthermore, it qualitatively examined the provision of spiritual care to clients in this parish nurse sample. Parish nurses scored high in spiritual perspective and spiritual well-being and reported an emphasis on health promotion and education in their activities. Three views of spiritual interventions (ideal, general, and specific) were reported. Types of spiritual interventions typically fell into one of four categories: religious, interactional, relational, and professional.

Adult↗
PubMed2001

Conceptualization of a new stroke-specific outcome measure: the stroke impact scale.

Current stroke outcome measures are unable to detect some consequences of stroke that affect patients, families, and providers. The objective of this study was to ensure the content validity of a new stroke outcome measure. This was a qualitative study using individual interviews with patients and focus group interviews with patients, caregivers, and health care professionals. Participants included 30 individuals with mild and moderate stroke, 23 caregivers, and 9 stroke experts. Qualitative analysis of the individual and focus group interviews generated a list of potential items. Consensus panels reviewed the potential items, established domains for the measure, developed item scales, and decided on mechanisms for administration and scoring. Although the participants with stroke appeared highly recovered based on scores from conventional stroke assessments (Barthel Index and NIH Stroke Scale), stroke survivors and their caregivers identified numerous persisting impairments, disabilities, and handicaps. In general, stroke survivors described themselves as only about 50% recovered and reported that they had difficulty in activities in which they were not independent. To fully assess the impact of stroke on patients, we used the results of this qualitative study to develop a new stroke-specific outcome, the Stroke Impact Scale.

Journal Article↗
PubMed2001

Lumpy skin disease in southern Africa: a review of the disease and aspects of control.

This article reviews some of the important aspects of lumpy skin disease (LSD) that may impact on its successful control. A resurgence of the disease in the last decade has highlighted some constraints of the Neethling strain vaccine, but there is no evidence of vaccine breakdowns owing to the presence of heterologous field strains. More research is needed on epidemiology and transmission of LSD in South Africa to formulate control measures.

Animals↗
PubMed2001

Iliac crest internal oblique osteomusculocutaneous free flap reconstruction of the postablative palatomaxillary defect.

BACKGROUND: Traditionally, restoration of extensive palatomaxillary defects have been achieved by prosthetic restoration, often with suboptimal functional results. More recently, vascularized bone-containing free flaps have been used for this purpose. OBJECTIVE: To describe 6 patients who underwent palatomaxillary reconstruction using the composite iliac crest-internal oblique osteomusculocutaneous free flap. METHODS: Six cases of iliac crest osteomusculocutaneous free flap reconstruction of extensive postablative palatomaxillary defects were retrospectively reviewed with clinical follow-up. We reviewed these cases for pathologic findings, defect size, dental restoration, oral rehabilitation, and speech. RESULTS: Pathologic findings included squamous cell carcinoma (n = 4), osteogenic sarcoma (n = 1), and sinonasal hemangiopericytoma (n = 1). Mean follow-up was 14.5 months (range, 10-25 months). Four patients underwent resection and reconstruction primarily and 2 underwent reconstruction secondarily. Two patients required reconstruction of a cutaneous defect using the iliac skin paddle. The hard palate and lateral nasal wall were reconstructed in all 6 patients, and the orbital rim and zygomatic body were reconstructed in 4. One patient underwent reconstruction with an orbital prosthesis supported by osseointegrated implants. There was 1 donor site complication and 1 recipient site infection, which was treated successfully with oral antibiotics. Four patients were rehabilitated with osseointegrated implants, and all 6 patients maintain an unrestricted oral diet. All 6 patients have normal speech without velopharyngeal or oronasal insufficiency. CONCLUSION: For extensive palatomaxillary defects, the iliac crest-internal oblique osteomusculocutaneous free flap offers a reliable method of primary reconstruction, allowing for complete orodental rehabilitation without the use of a prosthetic obturator.

Adult↗
PubMed2001

Current and emerging lupus treatments.

New developments in the treatment of lupus have been lacking until recently. It is hoped that new immunomodulating therapies, including a synthetic form of dehydroepiandrosterone (prasterone), will help reduce the need for steroid treatment among patients with mild-to-moderate disease, thereby reducing the morbidity and cost associated with steroid-related side effects. In addition, newer treatments for more severe systemic lupus erythematosus appear to be on the horizon, the most promising of which include biologic agents. Meanwhile, several improvements have been made to traditional therapies that may also benefit patients.

Adrenal Cortex Hormones↗
PubMed2001

Fall history is an independent predictor of adverse health outcomes and utilization in the elderly.

OBJECTIVE: To determine whether a history of falls predicts functional decline, adverse health events, and hospitalization. STUDY DESIGN: Twelve-month prospective cohort study. PATIENTS AND METHODS: Participants were members of a Medicare managed care program. Outcomes were assessed each quarter and included functional status, healthcare utilization (hospitalization), and adverse events (hospitalizations, nursing home placement, or death). Subject healthcare utilization diaries were corroborated with health system data files. RESULTS: At baseline, 70% reported no falls (NF), 18% had 1 fall (F), and 12% reported 2 or more falls (RF). Fall status predicted functional decline; new ADL deficits were seen in 18% of NF, 28% of F, and 55% of RF (P < or = .0001). Following adjustment for baseline function, this association remained predictive (adjusted odds ratio [OR] for new ADL deficits: 3.5, P = .007; and for new ADL and IADL deficits: 12.0, P= .0001). Fall frequency was a univariate predictor of adverse events (hospitalizations, nursing home placement, or death) and of hospital utilization alone. One or more adverse event(s) occurred in 18% of NF, 22% of F, and 38% of RF (P = .049). Hospitalization occurred in 16% of NF, 22% in F, and 35% of RF (P = .03). Following adjustment for likelihood of future hospitalization (P(ra)), these associations remained predictive for RF (adjusted OR for one or more adverse event[s]: 2.4, P = .05; OR for hospitalization 2.4, P = .06). CONCLUSIONS: Fall history predicts decline in function, hospitalization, and adverse events among a Medicare managed care population and remains independently predictive of poor outcomes after controlling for baseline function and likelihood of future hospitalization.

Accidental Falls↗
PubMed2000

Large-scale analysis of gene expression changes during acute and chronic exposure to [Delta]9-THC in rats.

Large-scale cDNA microarrays were employed to assess transient changes in gene expression levels following acute and chronic exposure to cannabinoids in rats. A total of 24,456 cDNA clones were randomly selected from a rat brain cDNA library, amplified by PCR, and arrayed at high density to investigate differential gene expression profiles following acute (24 h), intermediate (7 days), and chronic (21 days) exposure to Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the psychoactive ingredient of marijuana. Hippocampal mRNA probes labeled with (33)P obtained from both vehicle and Delta(9)-THC-treated animals were hybridized with identical cDNA microarrays. Results revealed a total of 49 different genes altered by Delta(9)-THC exposure; of these, 28 were identified, 10 had homologies to expressed sequence tags (ESTs), and 11 had no homology to known sequences in the GenBank database. Chronic or acute cannabinoid receptor activation altered expression of several genes (i.e., prostaglandin D synthase, calmodulin) involved in biochemical cascades of cannabinoid synthesis or cannabinoid effector systems. Other genes [i.e., neural cell adhesion molecule (NCAM), myelin basic protein], whose relation to cannabinoid system function was not immediately obvious, were also significantly altered. Verification of the changes obtained with the large-scale screen was determined by RNA dot blots in different groups of animals treated the same as those in the large-scale screen. Results are discussed in terms of the different types of genes affected at different times during chronic Delta(9)-THC exposure.

Animals↗
PubMed2000

Short- and intermediate-term clinical outcomes from direct myocardial laser revascularization guided by biosense left ventricular electromechanical mapping.

BACKGROUND: Direct myocardial revascularization (DMR) has been examined as an alternative treatment for patients with chronic refractory myocardial ischemic syndromes who are not candidates for conventional coronary revascularization. Methods and Results-We used left ventricular electromagnetic guidance in 77 patients with chronic refractory angina (56 men, mean age 61+/-11 years, ejection fraction 0.48+/-0.11) to perform percutaneous DMR with an Ho:YAG laser at 2 J/pulse. Procedural success (laser channels placed in prespecified target zones) was achieved in 76 of 77 patients with an average of 26+/-10 channels (range 11 to 50 channels). The rate of major in-hospital cardiac adverse events was 2.6%, with no deaths or emergency operations, 1 patient with postprocedural pericardiocentesis, and 1 patient with minor embolic stroke. The rate of out-of-hospital adverse cardiac events (up to 6 months) was 2.6%, with 1 patient with myocardial infarction and 1 patient with stroke. Exercise duration after DMR increased from 387+/-179 to 454+/-166 seconds at 1 month and to 479+/-161 seconds at 6 months (P=0.0001). The time to onset of angina increased from 293+/-167 to 377+/-176 seconds at 1 month and to 414+/-169 seconds at 6 months (P=0.0001). Importantly, the time to ST-segment depression (>/=1 mm) also increased from 327+/-178 to 400+/-172 seconds at 1 month and to 436+/-175 seconds at 6 months (P=0.001). Angina (Canadian Cardiovascular Society classification) improved from 3.3+/-0.5 to 2.0+/-1.2 at 6 months (P<0.001). Nuclear perfusion imaging studies with a dual-isotope technique, however, showed no significant improvements at 1 or 6 months. CONCLUSIONS: Percutaneous DMR guided by left ventricular mapping is feasible and safe and reveals improved angina and prolonged exercise duration for up to a 6-month follow-up.

Adult↗
PubMed2000

Sensory evoked potentials in SIV-infected monkeys with rapidly and slowly progressing disease.

Human immunodeficiency virus (HIV-1) infects the central nervous system (CNS) early in the course of disease progression and leads to some form of neurological disease in 40-60% of cases. Both symptomatic and asymptomatic HIV-infected subjects also show abnormalities in evoked potentials. As part of an effort to further validate an animal model of the neurological disease associated with lentiviral infection, we recorded multimodal sensory evoked potentials (EPs) from nine rhesus macaques infected with passaged strains of SIVmac (R71/E17), prior to and at 1 month intervals following inoculation. The latencies of forelimb and hindlimb somatosensory evoked potentials (SEP) and flash visual evoked potentials (VEP) were measured. Within 14 weeks of inoculation, all but two animals had progressed to end-stage disease (rapid progressors). The two animals with slowly progressing disease (AQ15 and AQ94) had postinoculation life spans of 109 and 87 weeks, respectively. No significant changes were observed in evoked potentials recorded during the control period or at any time in the animals with slowly progressing disease. However, all of the monkeys with rapidly progressing disease exhibited increases in latency for at least one evoked potential type. The overall mean increases in somatosensory and visual evoked potential peak latencies for the rapid progressors were 22.4 and 25.3%, respectively. For comparison, the changes in slow progressors were not significant (1.8 and -1.9%, respectively). These results, coupled with our previous finding of slowed motor evoked potentials in the same cohort of macaques (Raymond et al.: J Neurovirol 1999;5:217-231), demonstrate a broad and somewhat variable pattern of viral injury to both sensory and motor system structures, resembling the findings in HIV-infected humans. These results coupled with our earlier work demonstrating cognitive and motor behavioral impairments in the same monkeys support the use of the SIVmac-infected rhesus macaque as a model of AIDS-related neurological disease.

Animals↗
PubMed2000

Initiating abstinence in cocaine abusing dually diagnosed homeless persons.

This study measured effectiveness of behavioral day treatment plus abstinence contingent housing and work therapy (DT+) versus behavioral day treatment alone (DT). A randomized controlled trial assessed participants at baseline, 2 and 6 months. Participants (N=110) met criteria for cocaine abuse or dependence, non-psychotic mental disorders, and homelessness. DT+ achieved greater abstinence at 2 and 6 months and more days housed at 6 months than DT. Effectiveness of DT+ was demonstrated, with greatest impacts on abstinence outcomes. Results replicated earlier work demonstrating effectiveness of behavioral day treatment and contingency management as an effective combination for cocaine abusing homeless persons.

Adult↗
PubMed2000

Regulation of alternative splicing of CD45 by antagonistic effects of SR protein splicing factors.

CD45 is a transmembrane glycoprotein possessing tyrosine phosphatase activity, which is involved in cell signaling. CD45 is expressed on the surface of most leukocytes and can be alternatively spliced by the inclusion or skipping of three variable exons (4, 5, and 6 or A, B, and C) to produce up to eight isoforms. In T cells, the splicing pattern of CD45 isoforms changes after activation; naive cells express high m.w. isoforms of CD45 which predominantly express exon A (CD45RA), whereas activated cells lose expression of exon A to form low m.w. isoforms of CD45 including CD45RO. Little is known about the specific factors controlling the switch in CD45 splicing which occurs on activation. In this study, we examined the influence of the SR family of splicing factors, which, like CD45, are expressed in tissue-specific patterns and have been shown to modulate the alternative splicing of a variety of transcripts. We show that specific SR proteins have antagonistic effects on CD45 splicing, leading either to exon inclusion or skipping. Furthermore, we were able to demonstrate specific changes in the SR protein expression pattern during T cell activation.

Alternative Splicing↗
PubMed2000

Ability of laboratories to detect emerging antimicrobial resistance in nosocomial pathogens: a survey of project ICARE laboratories.

A proficiency testing project was conducted among 48 microbiology laboratories participating in Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology). All laboratories correctly identified the Staphylococcus aureus challenge strain as oxacillin- resistant and an Enterococcus faecium strain as vancomycin-resistant. Thirty-one (97%) of 32 laboratories correctly reported the Streptococcus pneumoniae strain as erythromycin-resistant. All laboratories testing the Pseudomonas aeruginosa strain against ciprofloxacin or ofloxacin correctly reported the organism as resistant. Of 40 laboratories, 30 (75%) correctly reported resistant MICs or zone sizes for the imipenem- and meropenem-resistant Serratia marcescens. For the extended-spectrum beta-lactamase (ESBL)-producing strain of Klebsiella pneumoniae, 18 (42%) of 43 laboratories testing ceftazidime correctly reported ceftazidime MICs in the resistant range. These results suggest that current testing generally produces accurate results, although some laboratories have difficulty detecting resistance to carbapenems and extended-spectrum cephalosporins. This highlights the need for monitoring how well susceptibility test systems in clinical laboratories detect emerging resistance.

Aminoglycosides↗