A method for characterizing stapes prostheses by their mechanical transfer function

In this contribution, we present and evaluate a method for characterizing stapes prostheses by their mechanical transfer function. The measurements were carried out after a stapedotomy surgery was performed in three human temporal bones conserved in 4% formaldehyde. The inner ear was drained of fluid. Successively, one of three different stapes prostheses was inserted. After such preparation, the prosthesis piston movement compared to the incus movement is measured with laser vibrometry. The magnitude transfer function considered is defined as the amplitude of the prosthesis piston movement compared to the amplitude of the incus movement. Measurements were made in a frequency range from 500Hz to 4kHz. The measured amplitudes roughly ranged between 10nm and 100nm. A great advantage of the presented method is the fact that only a small portion of the ossicular chain influences the measurement, mainly the joint between the prosthesis and the incus. Furthermore, the usage of cadaver temporal bones allows for an automated measurement setup, long term experiments and the access of measurement positions inapproachable during in vivo measurements. With this method, the different kinds of prostheses could be evaluated on incuses of different diameters.     

EEG changes in patients during the introduction of carbamazepine

This study evaluates the EEG changes during the standardized introduction of carbamazepine in 16 previously untreated neurological patients and their relationship to serum levels of carbamazepine and carbamazepine-10,11-epoxide. Therapy was started with a dosage of 400 mg carbamazepine b.i.d. and remained unchanged during the whole study period of 35 days. Frequency analysis of serial EEG records was performed by Fast Fourier Transformation. In comparison to the pretreatment period (1) the mean values of the total power and relative powers of the theta and delta bands increased and (2) the mean values of the relative power of the alpha band and the center frequency decreased. These changes were already established 3 days after the beginning of the treatment and remained constant during the observation period. There were marked interindividual differences. (3) There was no statistically significant correlation between serum levels of carbamazepine or carbamazepine-10,11-epoxide and the EEG parameters. Our results demonstrate that the degree of EEG change primarily reflects individual susceptibility to carbamazepine and its metabolite during the early stage of carbamazepine exposure and is not dose related.     

Childbirths and risk of female predominant and other autoimmune diseases in a population-based Danish cohort

To evaluate the possible biological role of pregnancy on the risk of autoimmune diseases we assessed associations between reproductive history and subsequent risk of autoimmune diseases characterized by female predominance and other autoimmune diseases. Our study cohort comprised 4.6 million Danes born since 1935 for whom a complete record of childbirths was available. Cohort members were followed for hospital contacts for 31 autoimmune diseases from 1982 to 2008. Female predominant autoimmune diseases were those with a female:male sex ratio >2:1. Ratios of first hospitalization rates were calculated using Poisson regression, adjusting for potential confounding by age, birth cohort, calendar period and marital status. During 45.5 million person-years of follow-up 102,260 women were hospitalized with one or more autoimmune diseases. Overall, compared with childless women, women with children were at a relative risk of 1.04 (1.02-1.06) for any autoimmune diseases, 1.11 (1.08-1.14) for female predominant and 0.97 (0.95-1.00) for other autoimmune diseases. Possibly biologically related associations with parity were found for Hashimoto thyroiditis (1.11; 1.00-1.24), Graves' disease (1.19; 1.14-1.24), erythema nodosum (1.15; 1.01-1.32), psoriasis (1.08; 1.01-1.15), sarcoidosis (1.17; 1.06-1.28) and systemic lupus erythematosus (0.83; 0.74-0.93). Especially the one-year postpartum period was associated with an increased risk of Hashimoto thyroiditis, Graves' disease and sarcoidosis. Overall, parity was associated with an 11% increased risk of female predominant autoimmune diseases. Pregnancies resulting in liveborn children therefore seem to contribute only little to the general female predominance in autoimmune diseases. However, for a number of autoimmune diseases; especially autoimmune thyroid diseases, erythema nodosum and sarcoidosis parity might somehow be involved in disease development.     

Hyperemesis, gestational hypertensive disorders, pregnancy losses and risk of autoimmune diseases in a Danish population-based cohort

The risk of some female predominant autoimmune diseases (ADs) has previously been shown to be higher in women who experience hyperemesis, gestational hypertensive disorders and idiopathic pregnancy losses. This study assessed the association between such pregnancy-related experiences and the subsequent risk of female predominant and other ADs. Our study cohort comprised 1.6 million Danish women born since 1955 for whom we had information about hyperemesis, gestational hypertensive disorders and pregnancy losses and subsequent hospital contacts for 31 ADs between 1982 and 2008. Ratios of first hospitalization rates (RRs) with 95% confidence intervals (CIs) were calculated using Poisson regression, adjusting for age, birth cohort, calendar period, marital status and childbirths. During 27.0 million person-years of follow-up 51,732 women were hospitalized with one or more ADs. Overall, compared with women without the specific pregnancy experiences, the risk of any AD was significantly increased for women with hyperemesis (RR = 1.41; 95% CI 1.30-1.51), gestational hypertensive disorders (1.21; 1.16-1.26), spontaneous abortions (1.10; 1.07-1.14), missed abortions (1.09; 1.04-1.13), stillbirths (1.25; 1.12-1.40), ectopic pregnancies (1.08; 1.02-1.14) and induced abortions (1.07; 1.04-1.09). Associations with female predominant ADs (i.e., ADs with a female:male ratio >2:1) were strongest in the first five years after the studied pregnancy experiences, but overall there was little difference between the RRs for groups of female predominant ADs and other ADs. Strong and potentially biological associations were observed for a number of specific ADs; including systemic lupus erythematosus, Graves' disease, type 1 diabetes mellitus and pernicious anemia, and for some specific ADs associations persisted even more than five years after the abnormal pregnancy experience. Abnormal pregnancies are associated with increased risk of certain ADs, possibly because of underlying immunologic or hormonal factors that predispose to both adverse pregnancy experiences and AD development.     

Thyroid-stimulating hormone (TSH): measurement of intracellular, secreted, and circulating hormone in Xenopus laevis and Xenopus tropicalis

Thyroid-stimulating hormone (TSH) is an important regulator of the hypothalamic-pituitary-thyroid (HPT) axis in Xenopus laevis. To evaluate the role of this hormone on developing tadpoles, immunologically-based Western blots and sandwich ELISAs were developed for measuring intracellular (within pituitaries), secreted (ex vivo pituitary culture), and circulating (serum) amounts. Despite the small size of the tadpoles, these methods were able to easily measure intracellular and secreted TSH, and circulating TSH was measurable in situations where high levels were induced. The method was validated after obtaining a highly purified and enriched TSH sample using anti-TSH-β antibodies conjugated to magnetic beads. Subsequent mass-spectrometric analysis of the bands from SDS-PAGE and Western procedures identified the presence of amino acid sequences corresponding to TSH subunits. The purified sample was also used to prepare standard curves for quantitative analysis. The Western and ELISA methods had limits of detection in the low nanogram range. While the majority of the developmental work for these methods was done with X. laevis, the methods also detected TSH in Xenopus tropicalis. To our knowledge this is the first report of a specific detection method for TSH in these species, and the first to measure circulating TSH in amphibians. Examples of the utility of the methods include measuring a gradual increase in pituitary TSH at key stages of development, peaking at stages 58-62; the suppression of TSH secretion from cultured pituitaries in the presence of thyroid hormone (T4); and increases in serum TSH following thyroidectomy.     

Meta-analysis: antibiotic prophylaxis to prevent peristomal infection following percutaneous endoscopic gastrostomy

BACKGROUND: Despite numerous guidelines recommending prophylactic antibiotics prior to percutaneous endoscopic gastrostomy, their use remains controversial. AIM: To conduct a systematic literature review and performed meta-analyses to determine the benefit of antibiotic prophylaxis for percutaneous endoscopic gastrostomy placement. METHODS: We performed a systematic literature review by searching healthcare databases and grey literature for randomized-controlled trials of antibiotic prophylaxis against wound infection after percutaneous endoscopic gastrostomy. Relative risks were calculated for individual trials and data pooled using fixed-effects model. Relative risk reduction, absolute risk reduction and number needed to treat were calculated and are reported with 95% confidence intervals. RESULTS: Ten randomized-controlled trials met the inclusion criteria and 1059 cases were pooled. Overall findings indicated that antibiotic prophylaxis resulted in a relative risk reduction of 64% and an absolute risk reduction of 15%. Number needed to treat to prevent one wound infection was 8. Cephalosporin prophylaxis was associated with a relative risk reduction of 64%, absolute risk reduction of 10% and number needed to treat of 10, whereas penicillin-based prophylaxis was associated with a relative risk reduction of 62%, absolute risk reduction of 13% and number needed to treat of 8. CONCLUSIONS: Antibiotic prophylaxis prior to percutaneous endoscopic gastrostomy is effective in reducing the incidence of percutaneous endoscopic gastrostomy site wound infection. Based on sensitivity analyses, penicillin-based prophylaxis should be the prophylaxis of choice.     

Fecal calprotectin: assessment of a rapid test

BACKGROUND: Calprotectin, a protein found mainly in neutrophil granulocytes, is used as an inflammatory marker, while the fecal concentration of the protein is used to detect gastrointestinal (GI) inflammation. MATERIAL AND METHODS: Fecal calprotectin in 100 stool samples was measured by the ELISA method and by a new rapid test. Eighty-two patients had fecal calprotectin measured for clinical reasons and delivered 95 stool samples. The rest were delivered by healthy volunteers. RESULTS: The association between the two tests was statistically significant (p<0.0001, chi(2) test). With calprotectin values <15 microg/g, the sensitivity and specificity of the new rapid test was 96 % (95 % confidence interval (CI), 87-100 %) and 70 % (CI, 55-83 %), respectively, with a negative predictive value of 94 % (CI, 81-99 %). With values >15 microg/g, the rapid test was less accurate, thus rendering results in this range difficult to interpret. CONCLUSIONS: The new rapid test is useful as a screening test for excluding GI inflammation when the cut-off of 15 microg/g is used. With fecal calprotectin concentrations >15 microg/g, the rapid test should be supplemented by quantitative measurement.