Optical waveguiding in bent-core liquid-crystal filaments

We demonstrate optical waveguiding in recently discovered free-standing bent-core liquid-crystal filaments. The bent-core liquid-crystal molecules in air self-assemble into a cylindrical geometry that is "solidlike" along the radial direction of the filament and liquid in the axial direction of the filament. These filaments are unique not only because they are fluids, but also because they are anisotropic. For this reason, their waveguiding properties not predictable need to be characterized. The light power transmitted through the filament was found to be independent of temperature from 180 degrees C to near room temperature. Initial defects of newly pulled filaments were found to self-anneal, thus leaving defect-free fibers, where light scattering was found to be insignificant. The absorbance was found to be strongly wavelength dependent in the visible regime and relatively small in the infrared range. A self-assembled optical waveguide with self-annealing fluid properties may have promising applications in optical communications or in optical microchips.

Interobserver agreement between primary graders and an expert grader in the Bristol and Weston diabetic retinopathy screening programme: a quality assurance audit

AIMS

To assess the quality and accuracy of primary grading in the Bristol and Weston diabetic retinopathy screening programme and to set standards for future interobserver agreement reports.

METHODS

A prospective audit of 213 image sets from six fully trained primary graders in the Bristol and Weston diabetic retinopathy screening programme was carried out over a 4-week period. All the images graded by the primary graders were regraded by an expert grader blinded to the primary grading results and the identity of the primary grader. The interobserver agreement between primary graders and the blinded expert grader and the corresponding Kappa coefficient was determined for overall grading, referable, non-referable and ungradable disease. The audit standard was set at 80% for interobserver agreement with a Kappa coefficient of 0.7.

RESULTS

The interobserver agreement bettered the audit standard of 80% in all the categories. The Kappa coefficient was substantial (0.7) for the overall grading results and ranged from moderate to substantial (0.59-0.65) for referable, non-referable and ungradable disease categories. The main recommendation of the audit was to provide refresher training for the primary graders with focus on ungradable disease.

CONCLUSION

The audit demonstrated an acceptable level of quality and accuracy of primary grading in the Bristol and Weston diabetic retinopathy screening programme and provided a standard against which future interobserver agreement can be measured for quality assurance within a screening programme. Diabet. Med. 26, 820-823 (2009).

Predictors of deep vein thrombosis (DVT) in newly diagnosed multiple myeloma (MM) patients with and without prophylactic recombinant erythropoietin (EPO) therapy

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Background: DVT, a complication among newly diagnosed MM patients, is most common during the first 3–4 months of therapy. EPO, given to treat anemia in patients receiving chemotherapy, has been associated with increased DVT risk and the mechanism, thought to be related to rise in hemoglobin, remains unknown. Methods: All 604 patients with newly diagnosed MM who completed the induction phase (∼ 3–4 months) of treatment were included. Induction consisted of multiagent chemotherapy with upfront randomization to thalidomide (THAL) or no THAL. 122 patients were also enrolled in an exercise study that included prophylactic EPO. Venous thromboembolism, defined as Doppler confirmed DVT and/or pulmonary embolus during induction, was the primary endpoint. Univariate analyses provided group comparisons. Logistic regression analysis determined predictors of DVT. Results: EPO and No EPO groups were similar for THAL use, age, race, gender, BMI, DVT history, and key baseline laboratory values except for lower cytogenetics risk score (p = 0.010) and higher albumin (p = 0.005), hemoglobin (p = 0.025) and fibrinogen (p = 0.0005) in the EPO group. EPO patients had a higher incidence of DVT 25 (20.5%) vs. 47 (9.8%) (p = 0.001). Risk factors for DVT by univariate analysis were THAL (p =0.001) and baseline platelets > 350,000/μL (p = 0.018) but not hemoglobin (at baseline or throughout study). There were no significant differences in MM response or survival between the groups with and without DVT. Compared to the No EPO group, EPO-treated patients had a better MM response (p = 0.023) and a higher survival (p = 0.0005). The main predictors of DVT by logistic regression were THAL and prophylactic EPO. Conclusions: THAL and prophylactic EPO predict for higher risk of DVT among newly diagnosed MM patients. Hemoglobin levels were not related to higher risk of DVT. DVT and EPO did not decrease treatment response or survival.

No significant financial relationships to disclose.

Fetal macrosomia in non-diabetic mothers: antenatal diagnosis and delivery outcome

This is a retrospective study of 74 non-diabetic women that delivered babies in excess of 4,500 g. The women were divided into two groups, depending on whether there had been suspected macrosomia antenatally or not. Mode of delivery and rates of induction of labour were examined. Women diagnosed with a macrosomic fetus were more likely to have elective caesarean sections or premature induction of labour. Those women in whom macrosomia was not suspected had higher rates of vaginal deliveries without any increase in neonatal morbidity.

Effect of memantine on CBF and CMRO2 in patients with early Parkinson's disease

OBJECTIVES

Parkinson's disease (PD) may be associated with increased energy metabolism in overactive regions of the basal ganglia. Therefore, we hypothesized that treatment with the N-methyl-d-aspartate receptor (NMDAR) antagonist memantine would decrease regional cerebral blood flow (rCBF) and oxygen metabolism in the basal ganglia of patients with early-stage PD.

METHODS

Quantitative positron emission tomography (PET) recordings were obtained with 15O]water and 15O]oxygen in 10 patients, scanned first in a baseline condition, and again 6 weeks after treatment with a daily dose of 20 mg memantine. Dynamic PET data were analyzed using volume of interest and voxel-based approaches.

RESULTS

The treatment evoked rCBF decreases in basal ganglia, and in several frontal cortical areas. The regional cerebral metabolic rate of oxygen (rCMRO2) did not decrease in any of the a priori defined regions, and consequently the oxygen extraction fraction was increased in these regions. Two peaks of significantly decreased rCMRO2 were detected near the frontal poles in both hemispheres, using a posteriori voxel-based analysis.

CONCLUSIONS

Although we did not find the predicted decrease in basal ganglia oxygen consumption, our data suggest that treatment with memantine actively modulates neuronal activity and/or hemodynamic response in basal ganglia of PD patients. This finding may be relevant to the putative neuroprotective properties of NMDAR antagonists.

Role of molecular shape on bent-core liquid-crystal structures

We show how frustrations in molecular packing generated by molecular substitutions and electrostatic potentials necessitate a local C1 symmetry and lead to spontaneous polarization splay and layer bending in bent-core liquid crystals. By estimation of the entropic changes due to curvature, we calculated the elastic constants that drive the spontaneous layer bend and polarization splay and obtained length scales of these deformations. Finally, we propose a structural phase diagram which describes how the experimentally observed helical superstructures, layer undulation, polarization splay, and spontaneous fiber formation depend on the direction and magnitude of the spontaneous polarization.

Structure and stability of bent core liquid crystal fibers

Recently it was found that fluid smectic phases of bent core liquid crystals formed freestanding fibers of extremely high slenderness ratios. Studies of these fibers showed that their structure was composed of concentric cylindrical smectic layers. For this configuration to be stable there must be an energy term that desires bending of the smectic layers. We show that an energy term that deals with the divergence of the dipolar direction can encourage layer bending if the layer chirality value is allowed to vary. The energy term associated with holding the layer chirality is closely related to layer compressions and electrical self-interactions. For our model, we assumed a simple smectic-C geometry with constant molecular tilt and cone angle defined by the director with respect to the layer normal, but allowed a constant variation of the polar direction about the director. Applying this simplified model to a free energy which accounts for director distortions, divergence of the polar direction, biaxial layer strain, surface tension, and electrical self-interactions, we were able to show consistency between the stable fiber radius and other properties predicted in our model to results from experimental studies.

The new 4DDome prosthesis: an original light and partially absorbable composite mesh for hernia repair

INTRODUCTION

The use of non-absorbable meshes for the repair of inguinal hernias has become standard; however, these meshes have been associated with complications including long-term postoperative pain. To this end, a new partially absorbable composite mesh has been developed, and the aim of this study was to investigate its efficacy in animal and human trials.

MATERIALS AND METHODS

Sixty male Wistar rats were used to evaluate the behavior of the newly designed composite mesh. Composite meshes were implanted in the extra-peritoneal plane for 2, 4 and 8 weeks and compared to a standard polypropylene mesh. Forty patients with symptomatic inguinal hernias were treated using a new 4DDome designed prosthesis. Follow-up was by clinical and ultrasound examination at 1, 6 and 12 months.

RESULTS

The animal study demonstrated that the inflammatory reaction associated with the new composite mesh was significantly lower than a standard polypropylene mesh, characterized by a lower macrophage infiltrate (P < 0.001). The mesh did not shrink over the 8-week period, unlike the polypropylene mesh (P < 0.05). The human study showed that there were three minor postoperative complications, no recurrences and the mesh was well tolerated. Follow-up with serial ultrasound showed that at 10 days and 1 month the dome was clearly visible in position; however, by 6 months it had flattened out, been partially absorbed and become incorporated into the repair.

CONCLUSION

These experimental and clinical studies have validated the concept of the new 4DDome composite mesh. It was well tolerated and was associated with good short-term results. The combination of the dome shape and the new composite mesh means that less polypropylene is required and represents a significant advance in anterior hernia repair.

Reported symptoms and quality-of-life impacts in patients having laser treatment for sight-threatening diabetic retinopathy

AIMS

To explore the patient experience of symptoms of eye disease related to diabetes and its treatment, including increase of symptoms over time and their relation to severity of the condition and the effect of multiple treatments and symptoms on quality of life.

METHODS

A qualitative interview study was implemented at four eye clinics in the UK. This study design was intended to yield 240 interviews in patients having their first laser treatment or first follow-up and in multi-treatment patients with a clinically documented loss of visual function in at least one eye (VA </= 6/12). The intention was to have an approximately equal number of patients with proliferative diabetic retinopathy (PDR) or macular oedema (MO).

RESULTS

A total of 227 interviews were completed (54% PDR and 46% MO). The most frequently reported symptom prior to initial treatment was blurred vision (55%). First-time-treatment patients reported fewer symptoms than the multi-treatment patients. After a pronounced reduction of quality-of-life impacts after the first laser treatment, results all demonstrate an increasing impact as patients move from first treatment to multiple treatments. The main responses regarding satisfaction with laser treatment were that, although patient expectations were basically met, the treatment had less of an impact than they hoped for, and they would have the treatment again if needed.

CONCLUSIONS

The current study provides a qualitative exploration of visual symptoms, levels of self-reported visual impairment, and general description of the areas of impact or restriction that patients experienced due to their eye disease, both pre- and post-laser treatment.

Older patients' experiences of treatment for colorectal cancer: an analysis of functional status and service use

Age and ageing are an important part of the context within which the care and treatment of people with cancer is provided. More information is needed about the effects of cancer treatment on the lives of older people following inpatient care. We conducted a 3-year study in which older people with colorectal cancer completed a detailed questionnaire on multidimensional function and service use before and after elective treatment. Here we present an analysis of changes in functional status and service use over the pre- to post-treatment period, and set out a detailed picture of older people's experiences before and after treatment. In total, 337 patients with colorectal adenocarcinoma aged 58-95 years were interviewed before treatment using the OARS Multidimensional Functional Assessment Questionnaire (OMFAQ), Rotterdam Symptom Checklist (RSCL) and a severity of morbidity score. Study end points were defined as post-treatment functional status, symptom distress, severity of morbidity and frequency of service use. Pre- and post-treatment data were compared using matched analyses. Logistic regression was used to assess associations between age and the main outcome measures, and frequency of service use after treatment was compared between age groups using the chi2 test. Overall, patients experienced both positive and negative outcomes following treatment. It was notable that patients aged > or = 75 years showed improvement in only one of the principal outcome measures. Patterns of service use following treatment suggest that support at home is a key issue for patients. With the exception of nursing care, however, help at home is provided on a majority of occasions by families themselves. This raises important questions about how much preparation patients and families receive or would like before they leave hospital after treatment for cancer. A collaborative, family-centred approach to meeting people's needs is called for in the months following inpatient care.

Serious lead poisoning in childhood: still a problem after a century

OBJECTIVE

To describe a series of patients with clinically significant lead poisoning.

METHODOLOGY

A case series of nine patients with lead poisoning who required inpatient management, identified through a Clinical Toxicology Service.

RESULTS

Nine children presented with clinically significant lead poisoning. The median serum lead was 2.5 micro mol/L (range 1.38-4.83). Eight of the children were exposed to lead-based paint, with seven due to dust from sanded lead paint during house renovations. Serial blood determinations suggested re-exposure in four of the patients, and in one of these patients the re-exposure was from a different source of lead. Eight of the patients required chelation therapy.

CONCLUSIONS

Serious lead poisoning continues to occur and there appears to be complacency regarding the hazard posed by lead paint in old houses.

Treatment decisions in older patients with colorectal cancer: the role of age and multidimensional function

The aim of the study was to investigate the role of age and multidimensional functional status in treatment decisions in older patients with colorectal cancer. Three hundred and thirty-seven patients aged 58-95 years with adenocarcinoma of the colon or rectum were interviewed before and after treatment using the OARS Multidimensional Functional Assessment Questionnaire (OMFAQ), a self-reported severity of morbidity scale, and the Rotterdam Symptom Checklist (RSCL). The OMFAQ rates five dimensions of function: social resources, economic resources, mental and physical health and self-care capacity. The likelihood of patients with Duke's C colorectal cancer receiving adjuvant chemotherapy decreased significantly with age (P = 0.001, trend). Differences in treatment received were not explained by differences in morbidity, economic, mental or physical function, self-care capacity, or any of the RSCL measures. After controlling for age, Duke's C patients who received adjuvant chemotherapy were less impaired in social resources than Duke's C patients who did not (P = 0.06). No other significant pre-treatment differences in functional status were found. Differences in age and social resources exist between patients who do and do not receive adjuvant chemotherapy. Care should be taken to ensure that patients are not excluded from treatment with known survival benefits because of their age, and the question of providing appropriate social support during adjuvant chemotherapy should be re-examined.

'Fit for purpose' health impact assessment: a realistic way forward

The UK government is committed to health impact assessment (HIA) as a means of ensuring that health will be a key consideration in policy formulation and other public decision making. However there has been some debate about whether current HIA practice can reliably inform decision making. In particular consultation with stakeholders and literature reviewing, key tools used in HIA, are said to suffer from a number of conceptual and methodological problems, which can undermine the validity of the assessment. In this paper, we argue that the philosophical nature of HIA, its purpose and its contribution to the promotion of public health is still being established. We outline our own HIA practice, which is based on a broad philosophy of 'fit for purpose' i.e. what is this HIA for and what is its spatial, temporal, social and political context. We suggest that it is important to guard against unrealistic expectations and illusions of total objectivity and precision in the HIA process. HIA 'screening' is capable of delivering benefits by making policies, programmes and projects, more health conscious. Once we move beyond this basic expectation and wish to be able to make judgements about the relative health benefits of alternative courses of action, the potential resource intensiveness of the process increases considerably. Even at a high level of resource usage any conclusions reached through the HIA process will always be, in part, subjective and therefore likely to be contested. We must decide what we want, what we are prepared to legislate for and what we are prepared to pay for in the HIA process.