Computation of the frequency response of a nonlinearly loaded antenna within a cavity

We analyze a nonlinearly loaded dipole antenna which is located within a rectangular cavity and excited by an electromagnetic signal. The signal is composed from two different frequencies. In order to calculate the spectrum of the resulting electromagnetic field within the resonator we transform the antenna problem into a network problem. This requires to precisely determine the antenna impedance within the cavity. The resulting nonlinear equivalent network is solved by means of the harmonic balance technique. As a result the occurrence of low intermodulation frequencies within the spectrum is verified

Polymorphisms in ARMS2/HTRA1 and complement genes and age-related macular degeneration in India: findings from the INDEYE study.

PURPOSE: Association between genetic variants in complement factor H (CFH), factor B (CFB), component 2 (C2), and in the ARMS2/HTRA1 region with age-related macular degeneration (AMD) comes mainly from studies of European ancestry and case-control studies of late-stage disease. We investigated associations of both early and late AMD with these variants in a population-based study of people aged 60 years and older in India. METHODS: Fundus images were graded using the Wisconsin Age-Related Maculopathy Grading System and participants assigned to one of four mutually exclusive stages based on the worse affected eye (0 = no AMD, 1-3 = early AMD, 4 = late AMD). Multinomial logistic regression was used to derive risk ratios (RR) accounting for sampling method and adjusting for age, sex, and study center. RESULTS: Of 3569 participants, 53.2% had no signs of amd, 45.6% had features of early amd, and 1.2% had late amd. CFH (RS1061170), C2 (RS547154), OR CFB (RS438999) was not associated with early or late AMD. In the ARMS2 locus, RS10490924 was associated with both early (adjusted RR 1.22, 95% confidence interval [CI]: 1.13-1.33, P < 0.0001) and late AMD (adjusted RR 1.81, 95% CI: 1.15-2.86; P = 0.01); rs2672598 was associated only with early AMD (adjusted RR 1.12, 95% CI: 1.02-1.23; P = 0.02); rs10490923 was not associated with early or late AMD. CONCLUSIONS: Two variants in ARMS2/HTRA1 were associated with increased risk of early AMD, and for one of these, the increased risk was also evident for late AMD. The study provides new insights into the role of these variants in early stages of AMD in India

Target- and Maturation-Specific Membrane-Associated Molecules Determine the Ingrowth of Entorhinal Fibers into the Hippocampus

AbstractIn this study the role of membrane-associated molecules involved in entorhinohippocampal pathfinding was examined. First outgrowth preferences of entorhinal neurites were analyzed on membrane carpets obtained from their proper target area, the hippocampus, and compared to preferences on control membranes from brain regions which do not receive afferent connections from the entorhinal cortex. On a substrate consisting of alternating lanes of hippocampal and control membranes, entorhinal neurites exhibited a strong tendency to grow on lanes of hippocampal membrane. These tissue-specific outgrowth preferences were maintained even on membrane preparations from adult brain tissue devoid of myelin. To determine the possible maturation dependence of these membranes, we examined guidance preferences of entorhinal neurites on hippocampal membranes of different developmental stages ranging from embryonic to postnatal and adult. Given a choice between alternating lanes of embryonic (E15–E16) and neonatal (P0–P1) hippocampal membranes, entorhinal neurites preferred to extend on neonatal membranes. No outgrowth preferences were observed on membranes obtained between E19 and P10. From P10 onward there was a reoccurrence of a preference for postnatal membrane lanes when neurites were presented with a choice between P15, P30, and adult membranes (>P60). This choice behavior of entorhinal neurites temporally correlates with the ingrowth of the perforant path into the hippocampus and with the stabilization of this brain area in vivo. Experiments in which postnatal and adult hippocampal membranes were heat inactivated or treated to remove molecules sensitive to phosphatidylinositol-specific phospholipase C demonstrated that entorhinal fiber preferences were controlled in this assay by attractive guidance cues and were independent of phosphatidylinositol-sensitive linked molecules. Moreover, entorhinal neurites displayed a positive discrimination for membrane-associated guidance cues of their target field, thus preferring to grow on membranes from the molecular layer of the dentate gyrus compared with CA3 or hilus membranes. Heat-inactivation experiments indicated that preferential growth of entorhinal axons is due to a specific attractivity of the molecular layer substrate. The data presented demonstrate that outgrowth of entorhinal fibers on hippocampal membranes is target and maturation dependent

Outcome of home haemodialysis patients: a case-cohort study

Background. Randomized, controlled comparisons between home haemodialysis (HHD) and centre haemodialysis (CHD) have not been performed to date. Reported survival benefits of HHD as compared with CHD from uncontrolled studies have been attributed largely to patient selection. Methods. In order to minimize a selection bias, we have compared the outcome of our HHD and CHD patients with a nested case-cohort study. For each patient trained for HHD at our dialysis centre between 1970 and 1995 (n = 103), a corresponding match was searched from the CHD patients by retrospective chart analysis. The pairs were matched for sex, age (±5 years), time of dialysis therapy onset (±2 years) and renal disease category. For 58 of the 103 HHD patients, a corresponding matched CHD patient was identified. Both treatment groups had the same mean age (50±13 years) at dialysis onset and were comparable with respect to the Khan comorbidity index, prevalence and duration of hypertension, smoking habits, history of myocardial infarction, stroke and peripheral vascular disease. In both groups, ∼50% of the patients were transplanted during the observation period. Results. HHD patients were hospitalized less often and tended to have fewer operations as compared with CHD patients. Survival was significantly longer in HHD as compared with CHD. Five, 10 and 20 year survival rates were 93 (n = 55 patients at risk), 72 (41) and 34% (11) with HHD and 64 (38), 48 (26) and 23% (4) with CHD, respectively. This survival difference persisted after adjusting for predictors of mortality, i.e. age at onset of dialysis, year of start of dialysis therapy and Khan comorbidity index. Conclusions. HHD offers a cheap and valuable alternative to CHD, with no apparent disadvantage

Safety of Oral Paracetamol – Analysis of Data from a Spontaneous Reporting System in Poland

Purpose: To determine the safety of oral coated paracetamol tablets 500 mg and oral suspension 120 mg/5 mL produced by Hasco-Lek Poland.Methods: We analyzed sales volume and data obtained from the  monitoring of spontaneous reports on the adverse effects of paracetamol collected in the period between November 2000 and June 2012.Results: A total of 45,694 units of coated paracetamol tablets (500 mg) and 6,048,289 units of paracetamol oral suspension (120 mg/5 mL) were marketed during that period. There were 4 spontaneous reports of adverse effects.Conclusion: Oral paracetamol is a safe medication rarely causing adverse effects but it is possible that the existing spontaneous monitoring system for adverse effects in Poland is not sensitive enough to detect all adverse effects, and needs improvement.Keywords: Adverse reaction, NSAIDs, Pharmacovigillance,  Pharmoepidemiolog

Prescription of renin-angiotensin system blockers and risk of acute kidney injury: a population-based cohort study.

OBJECTIVE: To investigate whether there is an association between use of ACE inhibitors (ACEI) and angiotensin receptor blockers (ARB) and risk of acute kidney injury (AKI). STUDY DESIGN: We conducted a new-user cohort study of the rate of AKI among users of common antihypertensives. SETTING: UK primary care practices contributing to the Clinical Practice Research Datalink (CPRD) eligible for linkage to hospital records data from the Hospital Episode Statistics (HES) database between April 1997 and March 2014. PARTICIPANTS: New users of antihypertensives: ACEI/ARB, β-blockers, calcium channel blockers and thiazide diuretics. OUTCOMES: The outcome was first episode of AKI. We estimated incidence rate ratio (RR) for AKI during time exposed to ACEI/ARB compared to time unexposed, adjusting for age, sex, comorbidities, use of other antihypertensive drugs and calendar period using Poisson regression. Covariates were time updated. RESULTS: Among 570 445 participants, 303 761 were prescribed ACEI/ARB with a mean follow-up of 4.1 years. The adjusted RR of AKI during time exposed to ACEI/ARB compared to time unexposed was 1.12 (95% CI 1.07 to 1.17). This relative risk varied depending on absolute risk of AKI, with lower or no increased relative risk from the drugs among those at greatest absolute risk. For example, among people with stage 4 chronic kidney disease (who had 6.69 (95% CI 5.57 to 8.03) times higher rate of AKI compared to those without chronic kidney disease), the adjusted RR of AKI during time exposed to ACEI/ARB compared to time unexposed was 0.66 (95% CI 0.44 to 0.97) in contrast to 1.17 (95% CI 1.09 to 1.25) among people without chronic kidney disease. CONCLUSIONS: Treatment with ACEI/ARB is associated with only a small increase in AKI risk while individual patient characteristics are much more strongly associated with the rate of AKI. The degree of increased risk varies between patient groups

Acute kidney injury and infections in patients taking antihypertensive drugs: a self-controlled case series analysis.

BACKGROUND: The relative risk of acute kidney injury (AKI) following different infections, and whether angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs) modify the risk, is unclear. We aimed to determine the risks of hospital admission with AKI following infections (urinary tract infection [UTI], lower respiratory tract infection [LRTI], and gastroenteritis) among users of antihypertensive drugs. METHODS: We used UK electronic health records from practices contributing to the Clinical Practice Research Datalink linked to the Hospital Episode Statistics database. We identified adults initiating ACEIs/ARBs or alternative antihypertensive therapy (β-blockers, calcium channel blockers, or thiazide diuretics) between April 1997 and March 2014 with at least 1 year of primary care registration prior to first prescription, who had a hospital admission for AKI, and who had a primary care record for incident UTI, LRTI, or gastroenteritis. We used a self-controlled case series design to calculate age-adjusted incidence rate ratios (IRRs) for AKI during risk periods following acute infection relative to noninfected periods (baseline). RESULTS: We identified 10,219 eligible new users of ACEIs/ARBs or other antihypertensives with an AKI record. Among these, 2,012 had at least one record for a UTI during follow-up, 2,831 had a record for LRTI, and 651 had a record for gastroenteritis. AKI risk was higher following infection than in baseline noninfectious periods. The rate ratio was highest following gastroenteritis: for the period 1-7 days postinfection, the IRR for AKI following gastroenteritis was 43.4 (95% CI=34.0-55.5), compared with 6.0 following LRTI (95% CI=5.0-7.3), and 9.3 following UTI (95% CI=7.8-11.2). Increased risks were similar for different antihypertensives. CONCLUSION: Acute infections are associated with substantially increased transient AKI risk among antihypertensive users, with the highest risk after gastroenteritis. The increase in relative risk is not greater among users of ACEIs/ARBs compared with users of other antihypertensives

Prevalence, incidence, indication, and choice of antidepressants in patients with and without chronic kidney disease: a matched cohort study in UK Clinical Practice Research Datalink.

PURPOSE: People with chronic kidney disease (CKD) have an increased prevalence of depression, anxiety, and neuropathic pain. We examined prevalence, incidence, indication for, and choice of antidepressants among patients with and without CKD. METHODS: Using the UK Clinical Practice Research Datalink, we identified patients with CKD (two measurements of estimated glomerular filtration rate < 60 mL/min/1.73m2 for ≥3 months) between April 2004 and March 2014. We compared those with CKD to a general population cohort without CKD (matched on age, sex, general practice, and calendar time [index date]). We identified any antidepressant prescribing in the six months prior to index date (prevalence), the first prescription after index date among non-prevalent users (incidence), and recorded diagnoses (indication). We compared antidepressant choice between patients with and without CKD among patients with a diagnosis of depression. RESULTS: There were 242 349 matched patients (median age 76 [interquartile range 70-82], male 39.3%) with and without CKD. Prevalence of antidepressant prescribing was 16.3 and 11.9%, and incidence was 57.2 and 42.4/1000 person-years, in patients with and without CKD, respectively. After adjusting for confounders, CKD remained associated with higher prevalence and incidence of antidepressant prescription. Regardless of CKD status, selective serotonin reuptake inhibitors were predominantly prescribed for depression or anxiety, while tricyclic antidepressants were prescribed for neuropathic pain or other reasons. Antidepressant choice was similar in depressed patients with and without CKD. CONCLUSIONS: The rate of antidepressant prescribing was nearly one and a half times higher among people with CKD than in the general population. © 2017 The Authors. Pharmacoepidemiology & Drug Safety Published by John Wiley & Sons Ltd

Methodological challenges when carrying out research on CKD and AKI using routine electronic health records.

Research regarding chronic kidney disease (CKD) and acute kidney injury (AKI) using routinely collected data presents particular challenges. The availability, consistency, and quality of renal data in electronic health records has changed over time with developments in policy, practice incentives, clinical knowledge, and associated guideline changes. Epidemiologic research may be affected by patchy data resulting in an unrepresentative sample, selection bias, misclassification, and confounding by factors associated with testing for and recognition of reduced kidney function. We systematically explore the issues that may arise in study design and interpretation when using routine data sources for CKD and AKI research. First, we discuss how access to health care and management of patients with CKD may have an impact on defining the target population for epidemiologic study. We then consider how testing and recognition of CKD and AKI may lead to biases and how to potentially mitigate against these. Illustrative examples from our own research within the UK are used to clarify key points. Any research using routine renal data has to consider the local clinical context to achieve meaningful interpretation of the study findings