193 research outputs found
Measurement of the main and critical parameters for optimal laser treatment of heart disease
Abstract: Laser light is frequently used in the diagnosis and treatment of patients. As in traditional treatments such as medication, bypass surgery, and minimally invasive ways, laser treatment can also fail and present serious side effects. The true reason for laser treatment failure or the side effects thereof, remains unknown. From the literature review conducted, and experimental results generated we conclude that an optimal laser treatment for coronary artery disease (named heart disease) can be obtained if certain critical parameters are correctly measured and understood. These parameters include the laser power, the laser beam profile, the fluence rate, the treatment time, as well as the absorption and scattering coefficients of the target treatment tissue. Therefore, this paper proposes different, accurate methods for the measurement of these critical parameters to determine the optimal laser treatment of heart disease with a minimal risk of side effects. The results from the measurement of absorption and scattering properties can be used in a computer simulation package to predict the fluence rate. The computing technique is a program based on the random number (Monte Carlo) process and probability statistics to track the propagation of photons through a biological tissue
Comparative Effectiveness of Total Population versus Disease-Specific Neural Network Models in Predicting Medical Costs
Does long-term care use within primary health care reduce hospital use among older people in Norway? A national five-year population-based observational study
<p>Abstract</p> <p>Background</p> <p>Population ageing may threaten the sustainability of future health care systems. Strengthening primary health care, including long-term care, is one of several measures being taken to handle future health care needs and budgets. There is limited and inconsistent evidence on the effect of long-term care on hospital use. We explored the relationship between the total use of long-term care within public primary health care in Norway and the use of hospital beds when adjusting for various effect modifiers and confounders.</p> <p>Methods</p> <p>This national population-based observational study consists of all Norwegians (59% women) older than 66 years (N = 605676) (13.2% of total population) in 2002-2006. The unit of analysis was defined by municipality, age and sex. The association between total number of recipients of long-term care per 1000 inhabitants (LTC-rate) and hospital days per 1000 inhabitants (HD-rate) was analysed in a linear regression model. Modifying and confounding effects of socioeconomic, demographic and geographic variables were included in the final model. We defined a difference in hospitalization rates of more than 1000 days per 1000 inhabitants as clinically important.</p> <p>Results</p> <p>Thirty-one percent of women and eighteen percent of men were long-term care users. Men had higher HD-rates than women. The crude association between LTC-rate and HD-rate was weakly negative. We identified two effect modifiers (age and sex) and two strong confounders (travel time to hospital and mortality). Age and sex stratification and adjustments for confounders revealed a positive statistically significant but not clinically important relationship between LTC-rates and hospitalization for women aged 67-79 years and all men. For women 80 years and over there was a weak but negative relationship which was neither statistically significant nor clinically important.</p> <p>Conclusions</p> <p>We found a weak positive adjusted association between LTC-rates and HD-rates. Opposite to common belief, we found that increased volume of LTC by itself did not reduce pressure on hospitals. There still is a need to study integrated care models for the elderly in the Norwegian setting and to explore further why municipalities far away from hospital achieve lower use of hospital beds.</p
Design and Synthesis of a Quintessential Self-Transmissible IncX1 Plasmid, pX1.0
DNA exchange in bacteria via conjugative plasmids is believed to be among the most important contributing factors to the rapid evolution- and diversification rates observed in bacterial species. The IncX1 plasmids are particularly interesting in relation to enteric bacteria, and typically carry genetic loads like antibiotic resistance genes and virulence factors. So far, however, a βpureβ version of these molecular parasites, without genetic loads, has yet to be isolated from the environment. Here we report the construction of pX1.0, a fully synthesized IncX1 plasmid capable of horizontal transfer between different enteric bacteria. The designed pX1.0 sequence was derived from the consensus gene content of five IncX1 plasmids and three other, more divergent, members of the same phylogenetic group. The pX1.0 plasmid was shown to replicate stably in E. coli with a plasmid DNA per total DNA ratio corresponding to approximately 3β9 plasmids per chromosome depending on the growth phase of the host. Through conjugation, pX1.0 was able to self-transfer horizontally into an isogenic strain of E. coli as well as into two additional species belonging to the family Enterobacteriaceae. Our results demonstrate the immediate applicability of recent advances made within the field of synthetic biology for designing and constructing DNA systems, previously existing only in silica
SCOTROC 2B: feasibility of carboplatin followed by docetaxel or docetaxelβirinotecan as first-line therapy for ovarian cancer
The feasibility of combination irinotecan, carboplatin and docetaxel chemotherapy as first-line treatment for advanced epithelial ovarian carcinoma was assessed. One hundred patients were randomised to receive four 3-weekly cycles of carboplatin (area under the curve (AUC) 7) followed by four 3-weekly cycles of docetaxel 100βmgβmβ2 (arm A, n=51) or docetaxel 60βmgβmβ2 with irinotecan 200βmgβmβ2 (arm B, n=49). Neither arm met the formal feasibility criterion of an eight-cycle treatment completion rate that was statistically greater than 60% (arm A 71% (90% confidence interval (CI) 58β81%; P=0.079; arm B 67% (90% CI 55β78%; P=0.184)). Median-dose intensities were >85% of planned dose for all agents. In arms A and B, 15.6 and 12.2% of patients, respectively, withdrew owing to treatment-related toxicity. Grade 3β4 sensory neurotoxicity was more common in arm A (1.9 vs 0%) and grade 3β4 diarrhoea was more common in arm B (0.6 vs 3.5%). Of patients with radiologically evaluable disease at baseline, 50 and 48% responded to therapy in arms A and B, respectively; at median 17.1 months' follow-up, median progression-free survival was 17.1 and 15.9 months, respectively. Although both arms just failed to meet the formal statistical feasibility criteria, the observed completion rates of around 70% were reasonable. The addition of irinotecan to first-line carboplatin and docetaxel chemotherapy was generally well tolerated although associated with increased gastrointestinal toxicity. Further exploratory studies of topoisomerase-I inhibitors in this setting may be warranted
Inference of reticulate evolutionary histories by maximum likelihood: the performance of information criteria
Background: Maximum likelihood has been widely used for over three decades to infer phylogenetic trees from
molecular data. When reticulate evolutionary events occur, several genomic regions may have conflicting
evolutionary histories, and a phylogenetic network may provide a more adequate model for representing the
evolutionary history of the genomes or species. A maximum likelihood (ML) model has been proposed for this
case and accounts for both mutation within a genomic region and reticulation across the regions. However, the
performance of this model in terms of inferring information about reticulate evolution and properties that affect
this performance have not been studied.
Results: In this paper, we study the effect of the evolutionary diameter and height of a reticulation event on its
identifiability under ML. We find both of them, particularly the diameter, have a significant effect. Further, we find
that the number of genes (which can be generalized to the concept of "non-recombining genomic regions") that
are transferred across a reticulation edge affects its detectability. Last but not least, a fundamental challenge with
phylogenetic networks is that they allow an arbitrary level of complexity, giving rise to the model selection
problem. We investigate the performance of two information criteria, the Akaike Information Criterion (AIC) and the
Bayesian Information Criterion (BIC), for addressing this problem. We find that BIC performs well in general for
controlling the model complexity and preventing ML from grossly overestimating the number of reticulation
events.
Conclusion: Our results demonstrate that BIC provides a good framework for inferring reticulate evolutionary
histories. Nevertheless, the results call for caution when interpreting the accuracy of the inference particularly for
data sets with particular evolutionary features
Screening for low bone mass with quantitative ultrasonography in a community without dual-energy X-ray absorptiometry: population-based survey
BACKGROUND: Dual-energy x-ray absorptiometry (DXA) is the criterion standard to identify low bone mineral density (BMD), but access to axial DXA may be limited or cost prohibitive. We screened for low bone mass with quantitative ultrasonography (QUS) in a community without DXA, analyzed its reliability and obtained reference values and estimated the prevalence of low QUS values. METHODS: We enrolled 6493 residents of Kinmen, Taiwan, and a reference group (96 men and 70 women aged 20β29 years) for this cross-sectional, community-based study. All participants completed a questionnaire and underwent ultrasonographic measurements. Reliability and validity of QUS measurements were evaluated. Broadband ultrasound attenuation (BUA) values were obtained and statistically analyzed by age, sex and weight. Annual loss of BUA was determined. Trends in the prevalence of QUS scores were evaluated. RESULTS: Two QUS were used and had a correlation coefficient of 0.90 (p < 0.001). Calcaneal BUA was significantly correlated with BMD in the femoral neck (r = 0.67, p < 0.001) and BMD of the total lumbar spine (r = 0.59, p < 0.001). BUAs in the reference group were 92.72 Β± 13.36 and 87.90 Β± 10.68 dB/MHz for men and women, respectively. Estimated annual losses of calcaneal BUA were 0.83% per year for women, 0.27% per year for men, and 0.51% per year for the total population. The prevalence of severely low QUS values (T-score = -2.5) tended to increase with aging in both sexes (p < 0.001). Across age strata, moderately low QUS values (-2.5 < T-score < -1.0) were 31.6β41.0% in men and 23.7β38.1% in women; a significant trend with age was observed in men (p < 0.001). CONCLUSION: Age-related decreases in calcaneal ultrasonometry, which reflected the prevalence of low bone mass, were more obvious in women than in men
Exopolysaccharide-Independent Social Motility of Myxococcus xanthus
Social motility (S motility), the coordinated movement of large cell groups
on agar surfaces, of Myxococcus xanthus requires type IV
pili (TFP) and exopolysaccharides (EPS). Previous models proposed that this
behavior, which only occurred within cell groups, requires cycles of TFP extension
and retraction triggered by the close interaction of TFP with EPS. However,
the curious observation that M. xanthus can perform TFP-dependent
motility at a single-cell level when placed onto polystyrene surfaces in a
highly viscous medium containing 1% methylcellulose indicated that βS
motilityβ is not limited to group movements. In an apparent further
challenge of the previous findings for S motility, mutants defective in EPS
production were found to perform TFP-dependent motility on polystyrene surface
in methylcellulose-containing medium. By exploring the interactions between
pilin and surface materials, we found that the binding of TFP onto polystyrene
surfaces eliminated the requirement for EPS in EPS- cells and thus
enabled TFP-dependent motility on a single cell level. However, the presence
of a general anchoring surface in a viscous environment could not substitute
for the role of cell surface EPS in group movement. Furthermore, EPS was found
to serve as a self-produced anchoring substrate that can be shed onto surfaces
to enable cells to conduct TFP-dependent motility regardless of surface properties.
These results suggested that in certain environments, such as in methylcellulose
solution, the cells could bypass the need for EPS to anchor their TPF and
conduct single-cell S motility to promote exploratory movement of colonies
over new specific surfaces
The First Molecular Phylogeny of Strepsiptera (Insecta) Reveals an Early Burst of Molecular Evolution Correlated with the Transition to Endoparasitism
A comprehensive model of evolution requires an understanding of the relationship between selection at the molecular and phenotypic level. We investigate this in Strepsiptera, an order of endoparasitic insects whose evolutionary biology is poorly studied. We present the first molecular phylogeny of Strepsiptera, and use this as a framework to investigate the association between parasitism and molecular evolution. We find evidence of a significant burst in the rate of molecular evolution in the early history of Strepsiptera. The evolution of morphological traits linked to parasitism is significantly correlated with the pattern in molecular rate. The correlated burst in genotypic-phenotypic evolution precedes the main phase of strepsipteran diversification, which is characterised by the return to a low and even molecular rate, and a period of relative morphological stability. These findings suggest that the transition to endoparasitism led to relaxation of selective constraint in the strepsipteran genome. Our results indicate that a parasitic lifestyle can affect the rate of molecular evolution, although other causal life-history traits correlated with parasitism may also play an important role
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