Exact traveling wave solutions of one-dimensional models of cancer invasion

In this paper we consider continuous mathematical models of tumour growth and invasion based on the model introduced by Chaplain and Lolas \cite{Chaplain&Lolas2006}, for the case of one space dimension. The models consist of a system of three coupled nonlinear reaction-diffusion-taxis partial differential equations describing the interactions between cancer cells, the matrix degrading enzyme and the tissue. For these models under certain conditions on the model parameters we obtain exact analytical solutions in terms of traveling wave variables. These solutions are smooth positive definite functions for some of which whose profiles agree with those obtained from numerical computations \cite{Chaplain&Lolas2006} for not very large time intervals.Comment: 19 pages, 6 figure

Exact Traveling Wave Solutions of One-Dimensional Parabolic-Parabolic Models of Chemotaxis

In this chapter we consider several different parabolic-parabolic systems of chemotaxis which depend on time and one space coordinate. For these systems we obtain the exact analytical solutions in terms of traveling wave variables. Not all of these solutions are acceptable for biological interpretation, but there are solutions that require detailed analysis. We find this interesting, since chemotaxis is present in the continuous mathematical models of cancer growth and invasion (Anderson, Chaplain, Lolas, et al.) which are described by the systems of reaction–diffusion-taxis partial differential equations, and the obtaining of exact solutions to these systems seems to be a very interesting task, and a more detailed analysis is possible in a future study

Lifestyle Counseling in Routine Care and Long-Term Glucose, Blood Pressure, and Cholesterol Control in Patients With Diabetes

OBJECTIVE In clinical trials, diet, exercise, and weight counseling led to short-term improvements in blood glucose, blood pressure, and cholesterol levels in patients with diabetes. However, little is known about the long-term effects of lifestyle counseling on patients with diabetes in routine clinical settings. RESEARCH DESIGN AND METHODS This retrospective cohort study of 30,897 patients with diabetes aimed to determine whether lifestyle counseling is associated with time to A1C, blood pressure, and LDL cholesterol control in patients with diabetes. Patients were included if they had at least 2 years of follow-up with primary care practices affiliated with two teaching hospitals in eastern Massachusetts between 1 January 2000 and 1 January 2010. RESULTS Comparing patients with face-to-face counseling rates of once or more per month versus less than once per 6 months, median time to A1C <7.0% was 3.5 versus 22.7 months, time to blood pressure <130/85 mmHg was 3.7 weeks versus 5.6 months, and time to LDL cholesterol <100 mg/dL was 3.5 versus 24.7 months, respectively (P < 0.0001 for all). In multivariable analysis, one additional monthly face-to-face lifestyle counseling episode was associated with hazard ratios of 1.7 for A1C control (P < 0.0001), 1.3 for blood pressure control (P < 0.0001), and 1.4 for LDL cholesterol control (P = 0.0013). CONCLUSIONS Lifestyle counseling in the primary care setting is strongly associated with faster achievement of A1C, blood pressure, and LDL cholesterol control. These results confirm that the findings of controlled clinical trials are applicable to the routine care setting and provide evidence to support current treatment guidelines

Following the money: copy-paste of lifestyle counseling documentation and provider billing

Background: Evidence suggests that copy-pasted components of electronic notes may not reliably reflect the care delivered. Federal agencies have raised concerns that such components may be used to justify inappropriately inflated claims for reimbursement. It is not known whether copied information is used to justify higher evaluation and management (E&M) charges. Methods: This retrospective cohort study aimed to assess the relationship between the level of evaluation and management (E&M) charges and the method of documentation (none, distinct or copied) of lifestyle counseling (diet, exercise and weight loss) for patients with diabetes mellitus. To determine the association, an ordered multinomial logistic regression model that corrected for clustering within individual providers and patients and adjusted for patient and encounter characteristics was utilized. E&M charge level served as the primary outcome variable. Patients were included if they were followed by primary care physicians affiliated with two academic hospitals for a minimum of two years between 01/01/2000 and 12/13/2009. Results: Lifestyle counseling was documented in 65.4% of 155,168 primary care encounters of 16,164 patients. Copied counseling was identified in 12,527 encounters. In multivariable analysis higher E&M charges were associated with older patient age, longer notes, treatment with insulin, medication changes and acute complaints. However, copied lifestyle counseling was associated with a decrease of 70.5% in the odds of higher E&M charge levels when time spent on counseling (required to justify higher charges based on counseling) was recorded (p<0.0001). This finding is opposite to what would have been expected if the impetus for copied documentation of lifestyle counseling was an increase in submitted E&M charges. Conclusion: There is no evidence that copied documentation of lifestyle counseling is used to justify higher evaluation and management charges. Higher charges were generally associated with indicators of complexity of care

Performance of Primary Care Physicians and Other Providers on Key Process Measures in the Treatment of Diabetes

OBJECTIVE Studies have shown that patients without a consistent primary care provider have inferior outcomes. However, little is known about the mechanisms for these effects. This study aims to determine whether primary care physicians (PCPs) provide more frequent medication intensification, lifestyle counseling, and patient encounters than other providers in the primary care setting. RESEARCH DESIGN AND METHODS This retrospective cohort study included 584,587 encounters for 27,225 patients with diabetes and elevated A1C, blood pressure, and/or LDL cholesterol monitored for at least 2 years. Encounters occurred at primary care practices affiliated with two teaching hospitals in eastern Massachusetts. RESULTS Of the encounters documented, 83% were with PCPs, 13% were with covering physicians, and 5% were with midlevel providers. In multivariable analysis, the odds of medication intensification were 49% (P < 0.0001) and 26% (P < 0.0001) higher for PCPs than for covering physicians and midlevel providers, respectively, whereas the odds of lifestyle counseling were 91% (P < 0.0001) and 21% (P = 0.0015) higher. During visits with acute complaints, covering physicians were even less likely, by a further 52% (P < 0.0001), to intensify medications, and midlevel providers were even less likely, by a further 41% (P < 0.0001), to provide lifestyle counseling. Compared with PCPs, the hazard ratios for time to the next encounter after a visit without acute complaints were 1.11 for covering physicians and 1.19 for midlevel providers (P < 0.0001 for both). CONCLUSIONS PCPs provide better care through higher rates of medication intensification and lifestyle counseling. Covering physicians and midlevel providers may enable more frequent encounters when PCP resources are constrained

Characterization of the Allosteric Properties of Thermus thermophilus Phosphofructokinase and the Sources of Strong Inhibitor Binding Affinity and Weak Inhibitory Response

Characterization of allosteric properties of phosphofructokinase from the extreme thermophile Thermus thermophilus (TtPFK) using thermodynamic linkage analysis revealed several peculiarities. Inhibition and activation of Fru-6-P binding by the allosteric effectors phosphoenolpyruvate (PEP) and MgADP are entropically-driven in TtPFK. It is also curious that PEP binding affinity is unusually strong in TtPFK when compared to PFKs from Escherichia coli, Bacillus stearothermophilus, and Lactobacillus delbrueckii, while the magnitude of the allosteric inhibition by PEP is much smaller in TtPFK. In an effort to understand the source of weak inhibition, a putative network of residues between the allosteric site and the nearest active site was identified from the three-dimensional structures of BsPFK. Three of the residues in this network, D59, T158, and H215, are not conserved in TtPFK, and, due to their nature (N59, A158, S215), are unlikely to be involved in the same non-covalent interactions seen in BsPFK. The triple chimeric substitution N59D/A158T/S215H, results in a 2.5 kcal mol-1 increase in the coupling free energy, suggesting that the region containing these residues may be important for propagation of inhibitory response. The individual substitutions at each position resulted in an increase in the coupling free energy, and the double substitutions displayed additivity of these changes. The chimeric substitution made at N59 suggests that the polar nature of the asparagine at position 59 is key for the enhanced binding of PEP. The non-conserved R55 was found to be particularly important for the enhanced binding of PEP in TtPFK, as chimeric substitutions R55G and R55E resulted in a 3.5 kcal mol-1 and 4.5 kcal mol-1 decrease in the binding affinity for PEP, respectively. Our results also confirm the observations previously made in PFKs from E. coli and B. stearothermophilus, that the ability of the effector to bind is independent of its ability to produce allosteric response. We show that several substitutions result in a decrease in binding affinity of PEP to TtPFK, while dramatically enhancing its ability to inhibit (N59D, R55G, R55E). Similarly, some substitutions, like S215H and A158T show an enhanced inhibition by PEP, while having no effect on its binding affinity

"Summary Page": a novel tool that reduces omitted data in research databases

<p>Abstract</p> <p>Background</p> <p>Data entry errors are common in clinical research databases. Omitted data are of particular concern because they are more common than erroneously inserted data and therefore could potentially affect research findings. However, few affordable strategies for their prevention are available.</p> <p>Methods</p> <p>We have conducted a prospective observational study of the effect of a novel tool called "<it>Summary Page</it>" on the frequency of correction of omitted data errors in a radiation oncology research database between July 2008 and March 2009. "<it>Summary Page</it>" was implemented as an optionally accessed screen in the database that visually integrates key fields in the record. We assessed the frequency of omitted data on the example of the <it>Date of Relapse </it>field. We considered the data in this field to be omitted for all records that had empty <it>Date of Relapse </it>field and evidence of relapse elsewhere in the record.</p> <p>Results</p> <p>A total of 1,156 records were updated and 200 new records were entered in the database over the study period. "<it>Summary Page</it>" was accessed for 44% of all updated records and for 69% of newly entered records. Frequency of correction of the omitted date of cancer relapse was six-fold higher in records for which "<it>Summary Page</it>" was accessed (p = 0.0003).</p> <p>Conclusions</p> <p>"<it>Summary Page</it>" was strongly associated with an increased frequency of correction of omitted data errors. Further, controlled, studies are needed to confirm this finding and elucidate its mechanism of action.</p