Equivalence of background and bleaching desensitization in isolated rod photoreceptors of the larval tiger salamander.

Psychophysical experiments have shown an equivalence between sensitivity reduction by background light and by bleaches for the human scotopic system. We have compared the effects of backgrounds and bleaches on the light-sensitive membrane-current responses of isolated rod photoreceptors from the salamander Ambystoma tigrinum. The quantum catch loss was factored out from the desensitization due to bleaching to give the fraction of "extra" desensitization due to adaptation. For backgrounds, desensitization is well described by the Weber/Fechner equation. The extra desensitization after bleaches can also be described by the Weber/Fechner equation, if an "equivalent" background produced by bleaching is made linearly proportional to the fraction of pigment bleached. A background which produces an extra desensitization of a factor of two is equivalent to a fractional bleach of approximately 6%. Equivalent background and bleaching desensitizations were associated with similar reductions in circulating current. There is a linear relation between log flash sensitivity and decrease in circulating current. Equivalent background and bleaching desensitizations were associated with similar increases in cGMP phosphodiesterase and guanylate cyclase activity. These were inferred from membrane current changes after steps into lithium or IBMX solutions. There were also similar reductions in the integration times of dim flash responses for equivalent desensitizations produced by backgrounds and bleaches. These results suggest that the equivalence between background and bleaching found psychophysically may arise at the very earliest stages of visual processing and that these two processes of desensitization have similar underlying mechanisms

Identifying consistent biomechanical parameters across rising-to-walk subtasks to inform rehabilitation in practice: A systematic literature review

© 2020 Elsevier B.V. Background: :The best approach to rehabilitate the control of everyday whole-body movement (e.g. rise-to-walk) after pathology remains unclear in part because the associated controlled performance variables are not known. Rise-to-walk can be performed fluidly (sit-to-walk) or non-fluidly (sit-to-stand, proceeded by gait-initiation). Biomechanical variables that remain consistent in health regardless of how rise-to walk is performed represent controlled performance variable candidates which could monitor rehabilitative change. Research Question: :To determine if any biomechanical parameters remain consistent across rising-to-walk (RTW) subtasks (sit-to-stand, gait-initiation, and sit-to-walk) in healthy adults for purposes of movement control assessment in clinical practice. Methods: :Data sources included Medline, Cinahl, and Scopus databases, and the grey literature. Study selection was based on eligibility criteria and must have reported spatiotemporal, kinematic and/or kinetic biomechanical parameters featuring >1 RTW subtask. Data extraction and synthesis; standardised-mean-differences (SMDs) were calculated (pooled if replicated in >1 study) for each parameter. Consistency was determined if SMD95 %CIs included the zero-effect line. Results: :Nine studies (n = 99) were included (40 ± 7.5yrs). Seven parameters were replicated in >1 study and subjected to meta-analysis (fixed-effect model). Two were consistent between sit-to-stand and sit-to-walk: flexion-momentum time (M(95 %CI) = 0.055(-0.423 to 0.533); p = 0.823) and peak whole-body-centre-of-mass vertical velocity (M(95 %CI)= -0.415(-0.898 to 0.069); p = 0.093); and centre-of-pressure to whole-body-centre-of-mass distance at toe-off (M(95 %CI)= -0.137(-0.712 to 0.439); p = 0.642) between gait-initiation and sit-to-walk. Another 20 parameters were consistent based on single-study SMDs. Significance: :Consistent parameters might exist across RTW subtasks. However, the evidence is based on few studies with small samples and variable RTW protocols. Future studies designed to confirm consistency using a standardised RTW protocol are needed

Approval of Waste Treatment and Immobilization Plant Contractor- Initiated Authorization Basis Amendment Requests (ABAR)

This report talks about Approval of Waste Treatment and Immobilization Plant Contractor- Initiated Authorization Basis Amendment Requests (ABAR

On sets of irreducible polynomials closed by composition

Let $\mathcal S$ be a set of monic degree $2$ polynomials over a finite field and let $C$ be the compositional semigroup generated by $\mathcal S$. In this paper we establish a necessary and sufficient condition for $C$ to be consisting entirely of irreducible polynomials. The condition we deduce depends on the finite data encoded in a certain graph uniquely determined by the generating set $\mathcal S$. Using this machinery we are able both to show examples of semigroups of irreducible polynomials generated by two degree $2$ polynomials and to give some non-existence results for some of these sets in infinitely many prime fields satisfying certain arithmetic conditions

Home ovulation tests and stress in women trying to conceive: a randomized controlled trial.

STUDY QUESTION: Does the use of a digital home ovulation test have any effect on the level of stress in women seeking to conceive? SUMMARY ANSWER: No difference was found in levels of stress between women using digital ovulation tests to time intercourse compared with women who were trying to conceive without any additional aids: in addition, their use did not negatively impact time to conception in users but may provide additional benefits, including an increased understanding of the menstrual cycle, reassurance and confidence in focusing conception attempts to the correct time in the cycle. WHAT IS KNOWN ALREADY: It has been suggested that timing of intercourse in such a way that it coincides with ovulation by using ovulation tests can lead to emotional distress; however, no study has been conducted to investigate this hypothesis specifically, until now. STUDY DESIGN, SIZE AND DURATION: The study was performed over two complete menstrual cycles as a prospective, randomized, controlled trial including quantitative and qualitative methods. The intervention (test) group were given digital ovulation tests to time intercourse to the most fertile time of the cycle and the control group were provided with the current National Institute for Health and Clinical Excellence guidelines for increasing the chances of conception (intercourse every 2-3 days) and asked not to use any additional methods to time when ovulation occurs. PARTICIPANTS/MATERIALS, SETTING AND METHODS: A total of 210 women who were seeking to conceive were recruited from the general UK population. A total of 115 women were randomized to the test group and 95 to the control group through block randomization. The positive and negative affect schedule (PANAS) and the Perceived Stress Scale (PSS) were used to measure subjective stress levels, the Short-Form 12 health survey was used as a measure of general health and well-being and urine samples were measured for biochemical markers of stress including urinary cortisol. Qualitative data were collected in the form of a telephone interview upon study completion. MAIN RESULTS AND THE ROLE OF CHANCE: There was no evidence for a difference either in total stress as measured using the PSS or in total positive or negative affect using the PANAS questionnaire between the test and control groups at any time point for the duration of the study. During cycle 1, for example, on Day 6, the difference in total stress score (test-control) was -0.62 [95% confidence interval (CI) -2.47 to 1.24] and on the day of the LH surge, it was 0.53 (95% CI -1.38 to 2.44). In addition, no correlation was observed between time trying to conceive and levels of stress, or between age and levels of stress, and no evidence was found to show that stress affected whether or not a pregnancy was achieved. There is also no evidence that the biochemistry measurements are related to whether a pregnancy was achieved or of a difference in biochemistry between the treatment groups. The use of digital ovulation tests did not negatively affect time to conception and with an adequately sized study, could potentially show improvement. To ensure that the results of this study were not affected by chance, we used a number of different methods for measuring stress, each of which had been independently validated. LIMITATIONS AND REASONS FOR CAUTION: Randomization occurred before the start of the study because of the need to provide the ovulation tests in readiness for Day 6 of the first cycle. As a consequence, a number of women fell pregnant during this period (22 and 13 in the test and control groups, respectively). A further 15 women were either lost to follow-up or withdrew consent prior to study start. Pregnancy rate was higher overall in the test group, so to ensure that there were sufficient data from women who failed to become pregnant in the test group, we implemented an additional biased recruitment. This second cohort may have been different from the first, although no significant differences were observed between the two phases of recruitment for any of the information collected upon admission to the study. WIDER IMPLICATIONS OF THE FINDINGS: Women who seek medical advice while trying to conceive should not be discouraged by health care professionals from using digital ovulation tests in order to time intercourse. The cohort of women recruited to this study initially had no evidence of infertility and were looking to conceive in a non-medical setting. A separate study to assess the impact of home ovulation tests in a subfertile population would be of interest and complementary to the present study. STUDY FUNDING/COMPETING INTERESTS: This study was funded by SPD Swiss Precision Diagnostics, GmbH, manufacturer of Clearblue(®) pregnancy and ovulation tests. SPD Development Company Ltd is a wholly owned subsidiary of SPD Swiss Precision Diagnostics GmbH; together referred to as SPD. TRIAL REGISTRATION NUMBER: NCT01084304 (www.clinicaltrials.gov)

A validated severity score for haemorrhoids as an essential prerequisite for future haemorrhoid trials.

BACKGROUND: There is a lack of standardised outcomes for haemorrhoidal disease making comparison between trials difficult. A need for a very well validated severity score is essential to facilitate meta-analysis of comparative studies, enabling evidence-based clinical practice. METHODS: The Hubble trial provides a large cohort of patients with haemorrhoidal disease randomised to rubber band ligation (RBL) or haemorrhoidal artery ligation. The haemorrhoid severity score (HSS) was collected on each patient at baseline, 6 weeks and 1 year after intervention. This allows for the responsiveness of the HSS instrument to be examined and compared with a more specific instrument, the Vaizey incontinence score (also collected). Responsiveness was tested using four methods (effect size, standardised response means (SRM), significance of change, and responsiveness statistic). RESULTS: The four tests of responsiveness demonstrated that the HSS was more responsive to changes in the patient's health status following both of the interventions compared to the Vaizey questionnaire. For example, between baseline and 6 weeks, the RBL intervention effect size scores and SRM calculations indicated a non-significant small amount of change (0.20 and 0.16 respectively). However, using the HSS, the effect size and SRM demonstrated a large magnitude of change (1.12 and 1.01, respectively) which was significant. Similar results were observed at 1 year. Significance of change scores and the index of responsiveness were also higher for the HSS questionnaire than the Vaizey across both treatment modalities. CONCLUSIONS: The HSS is a highly responsive tool for the detection of changes in haemorrhoid symptoms. It should form an essential patient-reported outcome tool for future studies on haemorrhoidal disease

The effects of irradiation on the biological and biomechanical properties of an acellular porcine superflexor tendon graft for cruciate ligament repair

Acellular xenogeneic tissues have the potential to provide ‘off‐the‐shelf’ grafts for anterior cruciate ligament (ACL) repair. To ensure that such grafts are sterile following packaging, it is desirable to use terminal sterilization methods. Here, the effects of gamma and electron beam irradiation on the biological and biomechanical properties of a previously developed acellular porcine superflexor tendon (pSFT) were investigated. Irradiation following treatment with peracetic acid was compared to peracetic acid treatment alone and the stability of grafts following long‐term storage assessed. Irradiation did not affect total collagen content or biocompatibility (determined using a contact cytotoxicity assay) of the grafts, but slightly increased the amount of denatured collagen in and decreased the thermal denaturation temperature of the tissue in a dose dependant fashion. Biomechanical properties of the grafts were altered by irradiation (reduced ultimate tensile strength and Young's modulus, increased failure strain), but remained superior to reported properties of the native human ACL. Long term storage at 4°C had no negative effects on the grafts. Of all the conditions tested, a dose of minimum 25 kGy of gamma irradiation had least effect on the grafts, suggesting that this dose produces a biocompatible pSFT graft with adequate mechanical properties for ACL repair

YouTube as a source of information for patients considering surgery for ulcerative colitis

© 2017 Elsevier Inc. Background With the range of health information online, assessing the resources that patients access may improve the content of preoperative information. Our aim was to assess the content of the most viewed videos on YouTube related to surgery for ulcerative colitis (UC). Methods YouTube was searched for videos containing information on surgery for UC. The 50 most viewed videos were identified and user interaction analyzed. Upload source was classified as patient, individual health care professional (HCP), or hospital/professional association. Video content was categorized using an inductive thematic analysis on a purposive sample list of videos. The overarching theme of each video was classified once data saturation was achieved. Results Thirty videos were uploaded by patients, 15 by hospitals and 5 by HCPs. Seventeen videos (34%) discussed life after surgery. Sixteen of these were uploaded by patients who had previously undergone surgery for UC. No videos of this theme were uploaded by HCPs. Ten videos (20%) described a number of different operations. Other themes identified were alternative health therapies (12%), colonoscopy (12%), life with UC (8%), miscellaneous (8%), and education for HCPs (6%). Patient uploaded videos had significantly more comments (P = 0.0079), with 28% of comments on patient videos being users requesting further information. Conclusions Understanding the sequelae of surgery is most important to preoperative patients. There are a lack of professional videos addressing this topic on YouTube. HCPs must participate in the production of videos and adapt preoperative consultations to address common preoperative concerns

What factors hinder the decision-making process for women with cancer and contemplating fertility preservation treatment?

Background: Although fertility preservation (FP) treatment options have increased, the existing evidence suggests that many women with cancer do not feel well supported in making these decisions, but find them stressful and complex and fail to take up fertility care at this crucial time. Whilst existing reviews have all made important contributions to our understanding of the FP decision-making process, none of them examine solely and specifically these processes for women of reproductive age with a diagnosis of any cancer, leaving a gap in the knowledge base. Given the expectation that care is patient-centred, our review aims to address this gap which may be of help to those managing patients struggling to make difficult decisions in the often brief period before potentially sterilising cancer treatment is started. Objective and rationale: Underpinning this narrative review was the question “What factors hinder the decision-making process for women with any cancer and contemplating FP treatment?” Our objectives were to i) assess and summarise this existing literature, ii) identify the factors that hinder this decision-making process, iii) explore to what extent these factors may differ for women choosing different methods of FP, and iv) make recommendations for service delivery and future research. Search methods: A systematic search of the medical and social science literature from the 1st January 2005 up to the end of January 2016 was carried out using three electronic databases (Web of Science (PubMed), Ovid SP Medline and CINAHL via Ebsco). Included in the review were quantitative, qualitative and mixed-method studies. Reference lists of relevant papers were also hand searched. From the 983 papers identified, 46 papers were included. Quality assessment was undertaken using the Mixed Methods Appraisal Tool and thematic analysis was used to analyse the data. Outcomes: From the analysis, six key themes with 15 sub-themes emerged: 1) fertility information provision (lack of information, timing of the information, patient-provider communication); 2) fear concerning the perceived risks associated with pursuing FP (delaying cancer treatment, aggravating a hormone positive cancer, consequences of a future pregnancy); 3) non-referral from oncology (personal situation, having a hormone positive cancer, not a priority, transition between service issues); 4) the dilemma (in survival mode, whether to prioritise one treatment over another); 5) personal situation (parity, relationship status); and 6) costs (financial concerns). Wider implications: This review has found that a wide range of internal and external factors impact the FP decision-making process. Key external issues related to current service delivery such as the provision and timing of FP information, and lack of referral from oncology to the fertility clinic. However, internal issues such as women’s fears concerning the perceived risks associated with pursuing FP also hindered decision-making but these ‘risks’ were typically overestimated and non-evidence based. These findings suggest that the implementation of a range of decision support interventions may be of benefit within the clinical care pathway of FP and cancer. Women would benefit from the provision of more evidence-based FP information, ideally received at cancer diagnosis, in advance of seeing a fertility specialist, for example through the implementation of patient decision aids. Health care professionals in both oncology and fertility services may also benefit from the implementation of training programs and educational tools targeted at improving the communication skills needed to improve collaborative decision-making and deliver care that is patient-centred. Exploration of the current barriers, both intellectual and practical, that prevent some patients from accepting FP will help care providers to do better for their patients in the future. Finally, the extent to which a poor prognosis and moral, ethical and religious beliefs influence the FP decision-making process also warrant further research