bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stable carbon isotopes and the metabolism of the terrestrial Devonian organism Spongiophyton
Authors: FLETCHER BENJAMIN J. , BEERLING DAVID J. , CHALONER WILLIAM. G. 
Published: July 2004

ABSTRACTDevonian fossils of Spongiophyton have been identified as a terrestrial evolutionary intermediate between algae and vascular land plants on the basis of their dichotomously branched, tubular morphology, thick cuticles, and the scattered distribution of surface pores. Our understanding of their physiology is, however, severely limited, but may be increased through the use of stable carbon isotope measurements. One such study led to the hypothesis that Spongiophyton carried a carbon isotope (δ13C) signature characteristic of lichens (Jahren et al., 2003Geology31, 99–102). Here, we outline three difficulties with accepting this idea and report independent isotopic measurements of Spongiophyton fossils from Canada and Ghana. Our results show that the isotopic discrimination of analogous tissues of Spongiophyton, extant lichens, liverworts and mosses are statistically indistinguishable. We suggest therefore that claims to have definitively identified lichen metabolism are premature, and cannot be sustained.
A novel method to assess systolic ventricular function using atrioventricular plane displacement – a study in young healthy males and patients with heart disease
Authors: Carlhäll C. , Hatle L. , Nylander E. 
Published: July 2004

SummaryAnalysis of atrioventricular plane displacement (AVPD) is a well established method for assessment of both systolic and diastolic ventricular function. For several years, AVPD has been a clinical tool and there are many current, as well as potential, areas of application. However, clinical work has shown that the traditional method for evaluation of systolic ventricular function, called total AVPD, does not temporally reflect true systole. Systolic AVPD is a new approach for measuring AVPD to assess ventricular systolic function. We wished to apply this new model in healthy subjects and in patients with different common heart diseases. Twenty‐eight young healthy males and 30 patients (aortic stenosis, left sided regurgitant lesions, postmyocardial infarction) were enrolled. AVPD was obtained at the four standard sites by M‐mode. Total AVPD was measured in the conventional way and systolic AVPD by identifying true systole, by means of mitral‐ and aortic valve closure respectively. Ventricular volumes were calculated according to biplane Simpson's rule. The systolic AVPD measurements were significantly lower than the total measurements, at both atrioventricular planes in all groups (P<0·001). This discrepancy was greater at the mitral than at the tricuspid annulus in the patients 24·2% vs. 15·5% (P<0·001), but did not differ in the healthy subjects. At the mitral annulus, this discrepancy also seemed to be more pronounced in the patients than in the healthy subjects 24·2% vs. 10·7%. When assessing ventricular systolic function by AVPD, the conventional method overestimates the amplitude in relation to true systolic function in both patients with heart disease and in young healthy males. Thus, there are uncertainties regarding earlier estimations of AVPD in terms of expression of systolic function and regarding previously presented reference values. We recommend the proposed methodology.
A computerized human reference brain for rCBF/SPET technetium‐99m exametazime (HMPAO) investigation of elderly
Authors: Sparring Björkstén Karin , Ekberg Stefan , Säfström Pia , Dige Niels , Granerus Göran 
Published: July 2004

SummaryUsing the bull's eye approach, a reference brain from the single photon emission tomography (SPET) images of 10 subjects aged 62–81 years with excellent mental and physical health was constructed. SPET images were acquired twice, 1 week apart, using a single detector rotating gamma camera collecting 64 planar images over a 360° orbit. The centre of each transaxial slice was first defined with an automatic edge detecting algorithm applied to an anterior–posterior and a side profile of the brain. Each slice was divided into 40 sectors. Maximum counts/pixel in each sector was picked. The 40 maximum count values from one transaxial slice were allowed to form a horizontal row in a new parametric image on the x‐axis and slice number from the vertex to the basal parts of the brain on the y‐axis. This new image was scaled to a 64 × 16 pixel matrix by interpolation, which meant a normalization of all studies to the same size. The parametric image in each subject was scaled with regard to intensity by a factor calculated by a normalization procedure using the least squares analysis. Mean and SD for each pixel were calculated, thereby constructing a ‘mean parametric image’, and a ‘SD parametric image’. These two images are meant to be used as the reference brain for evaluation of patient studies. This method can be used for objective measurements of diffuse brain changes and for pattern recognition in larger groups of patients. Statistical multifactorial analysis of parameters used for acquisition and data processing is possible.
Blood oxygen transport and endothelial dysfunction in patients with arterial hypertension
Authors: Zinchuk V. V. , Pronko T. P. , Lis M. A. 
Published: July 2004

SummaryDisturbed nitric oxide (NO) synthesis leads to development of endothelial dysfunction that plays a significant role in the pathogenesis of arterial hypertension. The presence of various compounds of haemoglobin with NO can affect haemoglobin‐oxygen affinity of the whole blood. Methaemoglobin and S‐nitrosohaemoglobin increase it, whereas nitrosyl‐haemoglobin decreases. The aim of this study was to investigate the blood oxygen transport indices and to assess the endothelial function in patients with arterial hypertension. The patients with mild hypertension had a 4·47% increased actual p50 (the blood pO2 corresponding to its 50% oxygen saturation) (P<0·05), a diminished pO2 (P<0·05), and a raised pCO2 (P<0·01) as compared with the controls. The patients with severe hypertension had decreased pO2 and pH, and actual p50 was reduced by 3·03% (P<0·05), which reflects a more pronounced oxyhaemoglobin dissociation curve shift leftwards. These changes can be assessed as a blood oxygen transport decompensation that enhanced tissue hypoxia. The results of our studies indicate that the endothelial dysfunction in patients with arterial hypertension leads to significant impairments in blood oxygen transport indices. The endothelium may be involved in development of the above blood oxygen transport impairments, since only sufficient amounts of NO maintain a normal blood flow and oxygen transport to tissues. The endothelial dysfunction leads to a disturbed production of different haemoglobin NO derivatives, which not only affects NO release at different sites of the arterial bed, but also haemoglobin‐oxygen affinity and optimal blood oxygenation and deoxygenation in capillaries. These data support the notion that endothelial dysfunction may alter haemoglobin‐oxygen affinity and tissue oxygen supply in vivo. Alternation of haemoglobin‐oxygen supply may be involved in the pathogenesis of hypertension.
Clinical performance of electronic, head‐mounted, low‐vision devices
Authors: Culham Louise E. , Chabra Anthony , Rubin Gary S. 
Published: July 2004

AbstractThis study compared four electronic head‐mounted devices (HMDs) (Jordy, Flipperport, Maxport and NuVision) with conventional optical low‐vision aids (LVAs). The aim was to determine any performance differences for laboratory‐based clinical measurements and practical visual tasks for patients with macular disease. Possible factors influencing success were explored. Ten patients with early onset macular disease (EOMD) and 10 with age‐related macular disease (AMD) used the four HMDs, habitual spectacles and previously prescribed optical LVAs to complete a range of clinical measurements and everyday visual tasks. The clinical measurements were distance, intermediate and near acuities, and contrast sensitivity. The visual tasks were to read text of three sizes, to write a cheque and to identify grocery items on a shelf. Following the initial evaluation, each subject took home two randomly selected HMD devices for 2 weeks, after which performance measures were repeated. No single HMD stood out as being superior overall. Flipperport and Jordy provided significantly better distance and intermediate acuity than the previously prescribed optical LVAs but near acuity and contrast sensitivity were not consistently better with any of the HMDs. Practice at home provided some improvement in performance with HMDs, nevertheless, optical aids remained the best devices for optimum functioning for the majority of tasks. Younger patients and those with better distance acuity were more likely to benefit from HMDs, particularly when reading small print. In low vision clinics, practitioners should continue to show patients conventional optical aids and demonstrate these electronic HMDs only when appropriate for the individual patient.
Fixation stability and reading speed in patients with newly developed macular disease*
Authors: Crossland Michael D. , Culham Louise E. , Rubin Gary S. 
Published: July 2004

AbstractBackground:  Patients with macular disease and central scotomas must use a peripheral, preferred retinal locus (PRL) in place of their damaged fovea. This paper investigates the development of the PRL, with particular reference to the stability of fixation.Methods:  Twenty‐five patients with age‐related and juvenile macular disease were recruited. All patients had developed a scotoma in their better eye within the previous 2 weeks. Patients were assessed using a scanning laser ophthalmoscope and an infra‐red gazetracker on four further occasions over the next 12 months.Results:  A linear relationship exists between reading speed and fixation stability for patients and control subjects. Fixation stability was not related to scotoma size, visual acuity or contrast sensitivity. Changes in fixation stability account for 54% of the variance in change in reading speed over the course of this study.Conclusions:  The deficit in reading speed in patients with macular disease can be partially attributed to impairments in fixation stability.
Size constancy in visual impairment: a comparison with normally sighted individuals*
Authors: Subramanian Ahalya , Dickinson Christine 
Published: July 2004

AbstractSize judgements are usually based on size constancy. However, as the number of visual cues decreases, such as by decreasing the field of view, size judgements gradually change from those based on size constancy to those based on the visual angle. The present study investigated whether visually impaired (VI) individuals, most of whom do not have measurable stereoacuity and have visual field defects, might therefore make judgements based on visual angle rather than size constancy. Size constancy was measured on 42 VI and 20 normally sighted subjects. Results indicated that size judgements are similar for both VI and normally sighted individuals at 0.50 m, 1 and 2 m. Statistically significant differences were found at 3 m. Despite this it would appear that VI individuals are able to make judgements based on size constancy rather than the visual angle.
Low vision services in South Devon: a multi‐agency, multi‐disciplinary approach*
Authors: Collins John , Skilton Kate 
Published: July 2004

AbstractSince 1994, the Low Vision Service in South Devon has been provided by a multi‐agency, multi‐disciplinary team. The team comprises of staff from Devon Social Services Sensory Team, Optima Low Vision Services Ltd, Royal National Institute for the Blind (RNIB) Manor House, Devon and Torbay Special Education Services and South Devon Healthcare Trust. In the 9 years of operation this service has been independently audited twice for patient satisfaction levels and compliance level in the use of low vision aids (LVAs). The results of the most recent service audit questionnaire reveal a high and constant patient satisfaction level with 92% of patients who answered the question reporting that the service was sufficient to meet their needs. The number of patients who used LVAs at least weekly was 88% of those answering the question. Plans for the future expansion of the service include the further development of interdisciplinary working.
Evaluation of a prototype Minified Augmented‐View device for patients with impaired night vision*
Authors: Bowers Alex R. , Luo Gang , Rensing Noa M. , Peli Eli 
Published: July 2004

AbstractAn evaluation was carried out of the first prototype (LV‐3) of a new night vision device, which incorporates visual field expansion through minification (Minified Augmented‐View), to provide feedback for continuing development. Six subjects with night blindness completed visual function measurements and indoor mobility assessments without a device, with the LV‐3 and with a commercially available comparison device (the Multi‐Vision) at light levels representative of well lit and poorly lit streets. Device performance and potential benefits in real‐world situations were evaluated at four outdoor locations (well lit to very dark). Results indicate that the see‐through nature and spectacle‐frame mounting of the LV‐3 address some of the cosmetic and ergonomic disadvantages of currently available devices; however insufficient light sensitivity of the prototype camera limited LV‐3 performance. With improved camera sensitivity and full implementation of the Minified‐Contours Augmented‐View concept in the next prototype, patients might be able to make better use of the novel field expansion and vision multiplexing features to aid outdoor night mobility.
Quality of Health Care: The Views of Homeless Youth
Authors: Ensign Josephine 
Published: July 2004

Objective. To develop homeless‐youth‐identified process and outcome measures of quality of health care.Data Sources/Study Setting. Primary data collection with homeless youth from both street and clinic settings in Seattle, Washington, for calendar year 2002.Study Design. The research was a focused ethnography, using key informant and in‐depth individual interviews as well as focus groups with a purposeful sample of 47 homeless youth aged 12–23 years.Data Collection/Extraction Methods. All interviews and focus groups were tape‐recorded, transcribed, and preliminarily coded, with final coding cross‐checked and verified with a second researcher.Principal Findings. Homeless youth most often stated that cultural and interpersonal aspects of quality of care were important to them. Physical aspects of quality of care reported by the youth were health care sites separate from those for homeless adults, andsites that offered a choice of allopathic and complementary medicine. Outcomes of health care included survival of homelessness, functional and disease‐state improvement, and having increased trust and connections with adults and with the wider community.Conclusions. Homeless youth identified components of quality of care as well as how quality of care should be measured. Their perspectives will be included in a larger follow‐up study to develop quality of care indicators for homeless youth.
Competing Values of Emergency Department Performance: Balancing Multiple Stakeholder Perspectives
Authors: Tregunno Deborah , Ross Baker G. , Barnsley Jan , Murray Michael 
Published: July 2004

Objective.To describe the performance interests of multiple stakeholders associated with the management and delivery of emergency department (ED) care, and to develop a performance framework and set of indicators that reflect these interests.Study Setting.Stakeholders (1,100 physicians, nurses, managers, home care providers, and prehospital care personnel) with responsibility for ED patients in hospitals in the Canadian province of Ontario.Study Design.Sixty‐two percent of stakeholders responded to a mail survey regarding the importance of 104 potential ED performance indicators. Descriptive and inferential statistics are used to explore the interests of each stakeholder group and to compare interests across the five groups.Principal Findings.Emergency department stakeholders are primarily interested in indicators that focus on their role and capacity to provide care. Key differences exist between hospital and nonhospital stakeholders. Physicians mean ratings of the importance on ED performance measures were lower than mean ratings in the other stakeholder groups.Conclusions.Emergency department performance interests are not homogeneous across stakeholder groups, and evaluating performance from the perspective of any one stakeholder group will result in unbalanced assessments. Community‐based stakeholders, a group frequently excluded from commenting on ED performance, provide important insights into ED performance related to the external environment and the broader continuum of care.
The Relationship of Medicaid Payment Rates, Bed Constraint Policies, and Risk‐Adjusted Pressure Ulcers
Authors: Grabowski David C. , Angelelli Joseph J. 
Published: July 2004

Objective. To examine the effect of Medicaid reimbursement rates on nursing home quality in the presence of certificate‐of‐need (CON) and construction moratorium laws.Data Sources/Study Setting. A single cross‐section of Medicaid certified nursing homes in 1999 (N=13,736).Study Design. A multivariate regression model was used to examine the effect of Medicaid payment rates and other explanatory variables on risk‐adjusted pressure ulcer incidence. The model is alternatively considered for all U.S. nursing home markets, those most restrictive markets, and those high‐Medicaid homes to isolate potentially resource‐poor environments.Data Extraction Methods. A merged data file was constructed with resident‐level information from the Minimum Data Set, facility‐level information from the On‐Line, Survey, Certification, and Reporting (OSCAR) system and market‐ and state‐level information from various published sources.Principal Findings. In the analysis of all U.S. markets, there was a positive relationship between the Medicaid payment rate and nursing home quality. The results from this analysis imply that a 10 percent increase in Medicaid payment was associated with a 1.5 percent decrease in the incidence of risk‐adjusted pressure ulcers. However, there was a limited association between Medicaid payment rates and quality in the most restrictive markets. Finally, there was a strong relationship between Medicaid payment and quality in high‐Medicaid homes providing strong evidence that the level of Medicaid payment is especially important within resource poor facilities.Conclusions. These findings provide support for the idea that increased Medicaid reimbursement may be an effective means toward improving nursing home quality, although CON and moratorium laws may mitigate this relationship.
The Impact of Medicaid Managed Care on Pregnant Women in Ohio: A Cohort Analysis
Authors: Howell Embry M. , Dubay Lisa , Kenney Genevieve , Sommers Anna S. 
Published: July 2004

Objective. To examine the impact of mandatory HMO enrollment for Medicaid‐covered pregnant women on prenatal care use, smoking, Cesarean section (C‐section) use, and birth weight.Data Sources/Study Setting. Linked birth certificate and Medicaid enrollment data from July 1993 to June 1998 in 10 Ohio counties, 6 that implemented mandatory HMO enrollment, and 4 with low levels of voluntary enrollment (under 15 percent). Cuyahoga County (Cleveland) is analyzed separately; the other mandatory counties and the voluntary counties are grouped for analysis, due to small sample sizes.Study Design. Women serve as their own controls, which helps to overcome the bias from unmeasured variables such as health beliefs and behavior. Changes in key outcomes between the first and second birth are compared between women who reside in mandatory HMO enrollment counties and those in voluntary enrollment counties. County of residence is the primary indicator of managed care status, since, in Ohio, women are allowed to “opt out” of HMO enrollment in mandatory counties in certain circumstances, leading to selection. As a secondary analysis, we compare women according to their HMO enrollment status at the first and second birth.Data Collection/Extraction Methods. Linked birth certificate/enrollment data were used to identify 4,917 women with two deliveries covered by Medicaid, one prior to the implementation of mandatory HMO enrollment (mid‐1996) and one following implementation. Data for individual births were linked over time using a scrambled maternal Medicaid identification number.Principal Findings. The effects of HMO enrollment on prenatal care use and smoking were confined to Cuyahoga County, Ohio's largest county. In Cuyahoga, the implementation of mandatory enrollment was related to a significant deterioration in the timing of initiation of care, but an improvement in the number of prenatal visits. In that county also, women who smoked in their first pregnancy were less likely to smoke during the second pregnancy, compared to women in voluntary counties. Women residing in all the mandatory counties were less likely to have a repeat C‐section. There were no effects on infant birth weight. The effects of women's own managed care status were inconsistent depending on the outcome examined; an interpretation of these results is hampered by selection issues. Changes over time in outcomes, both positive and negative, were more pronounced for African American women.Conclusions. With careful implementation and attention to women's individual differences as in Ohio, outcomes for pregnant women may improve with Medicaid managed care implementation. Quality monitoring should continue as Medicaid managed care becomes more widespread. More research is needed to identify the types of health maintenance organization activities that lead to improved outcomes.
The Effect of Benefits, Premiums, and Health Risk on Health Plan Choice in the Medicare Program
Authors: Atherly Adam , Dowd Bryan E. , Feldman Roger 
Published: July 2004

Objective. To estimate the effect of Medicare+Choice (M+C) plan premiums and benefits and individual beneficiary characteristics on the probability of enrollment in a Medicare+Choice plan.Data Source. Individual data from the Medicare Current Beneficiary Survey were combined with plan‐level data from Medicare Compare.Study Design. Health plan choices, including the Medicare+Choice/Fee‐for‐Service decision and the choice of plan within the M+C sector, were modeled using limited information maximum likelihood nested logit.Principal Findings. Premiums have a significant effect on plan selection, with an estimated out‐of‐pocket premium elasticity of −0.134 and an insurer‐perspective elasticity of −4.57. Beneficiaries are responsive to plan characteristics, with prescription drug benefits having the largest marginal effect. Sicker beneficiaries were more likely to choose plans with drug benefits and diabetics were more likely to pick plans with vision coverage.Conclusions. Plan characteristics significantly impact beneficiaries' decisions to enroll in Medicare M+C plans and individuals sort themselves systematically into plans based on individual characteristics.