1,721,071 research outputs found
Direct electrochemistry of membrane-entrapped horseradish peroxidase. Part II: Amperometric detection of hydrogen peroxide
No full textDirect (unmediated) electrochemistry of horseradish peroxidase (HRP) immobilized within a polymeric film is investigated at a pyrolytic graphite electrode by de cyclic voltammetry, in the absence and in the presence of hydrogen peroxide. Under the latter condition. a reduction wave centered at approx. -280 mV (vs. SCE) is observed, the intensity of which is strictly dependent on the hydrogen peroxide concentration. This permits a voltammetric investigation of the electrocatalytic reduction of hydrogen peroxide. Flow and flow-injection measurements carried out at constant potential under the same conditions, support voltammetric data. The suitability of the immobilized HRP-based electrodic system to monitor the presence of important analytes, such as glucose or choline, in solution, is also discussed. To this issue, suitable amounts of HRP and glucose oxidase (or, in turn, choline oxidase) were simultaneously entrapped in the polymer. The results obtained are of potential value for basic and applied biochemistry and represent a first step for construction of a mediator-free (third-generation) biosensor which may find application in the biosensoristic area. (C) 1998 Elsevier Science S.A. All rights reserved
Perceived knowledge, coping and diagnostic-therapeutic pathways of infertile couples trying to conceive: an Italian survey
No full textBackground: The last decades' increasing infertility risk factors have brought to a growing number of infertile couples. Knowledge regarding infertility and possible treatments is-however- poor, leading to difficulty in coping and understanding. Knowing infertile couples' perceptions and needs may help clinicians develop services that better address these needs.
Methods: This study aimed at assessing perceived knowledge, coping mechanisms and diagnostic-therapeutic pathways concerning infertility and Assisted Reproductive Technology (ART) in a sample of Italian infertile couples trying to conceive. In this cross-sectional study, 199 subjects aged 25-55 years old who had difficulties conceiving were asked to fill a questionnaire regarding infertility and ART perceived knowledge, coping and diagnostic-therapeutic pathways they had been through.
Results: The perceived knowledge score was 42.5%. Couples had difficulties understanding ART's success rate and the potential risks for the woman and fetus. Subjects from North of Italy, who were previously engaged in an ART procedure, those who had signed a written informed consent and were offered a specific counselling session had significantly higher mean score of perceived knowledge. Couples were handling the situation in a satisfactory way, supported also by their family, but the procedures, clinical examinations, therapies, medications, were considered complex and stressful by 66.5% of the respondents.
Conclusions: Healthcare providers should consider the couples' previous experience with infertility, the important role of informed consent and personalized counselling sessions. Counselling for infertile couples should have a broader, comprehensive approach, integrating psychological, social, ethical support, as well as health literacy, taking into consideration the infertile couples' preferences and needs
Direct electrochemical evidence for an equilibrium intermediate in the guanidine-induced unfolding of cytochrome c
No full textThis paper reports a voltammetric and spectroscopic investigation of the guanidine-induced unfolding of cytochrome c at neutral pH and 25 degrees C. Electrochemical data provide direct evidence for the presence of an equilibrium intermediate (form I) strictly dependent on the denaturant concentration. The midpoint potential of farm I has been determined (E(1/2) = +0.010 V vs. NHE) and its structural features defined rom analysis of the circular dichroism and absorbance spectroscopy data obtained under the same experimental conditions. From the correlation of electrochemical and spectroscopic data, we propose that the features detected by the intermediate conform to the molten globule state
Accuracy of continuous subcutaneous glucose monitoring in detecting hypoglycemia in diabetic patients
No full textA glucose biosensor based on electro-enzyme catalyzed oxidation of glucose using a HRP-GOD layered assembly
No full textThe assembly and the characterization (by DC cyclic voltammetry and flow injection analysis (FIA) mode) of a bienzymatic biosensor for glucose is described. The biosensor is constituted by a glucose oxidase (GOD)-entrapping cellulose triacetate membrane, layered onto a polymeric membrane (polystyrene cross-linked with 1% divinyl benzene functionalized with tributylmethyl phosphonium chloride (TBMPC)) embedding horseradish peroxidase (HRP), previously blocked onto a pyrolitic graphite electrode (PGE). Under flowing conditions, the biosensor, which gives place to direct, unmediated electron-transfer, responds linearly to the glucose up to 5.0 MM with a precison always better than 5%, and the detection limit was 0.07 mM. The influence of different experimental parameters, like temperature, flow rate, applied potential, interferents, etc., has been evaluated. For what concerns the potential interferences, no interfering species, as ascorbic acid, urea, etc., affects the biosensor response. The biosensor, characterized by an operational stability of at least twenty days, has been successfully tested on real samples
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Direct electrochemistry of membrane-entrapped horseradish peroxidase. Part I. A voltammetric and spectroscopic study
No full textThis paper reports the electrochemical behaviour, relative to the Fe(III)-Fe(II) conversion, of horseradish peroxidase (HRP) entrapped within a solid matrix, at a pyrolytic graphite electrode. The results indicate that (i) immobilization enhances the electron exchange between the protein and the electrode surface; (ii) reversible electron transfer (eT) is achieved within a wide pH range (pH 3.0-12.0) even in the absence of mediators, (ii) the embedded protein shows native-like structural properties and increased stability. The results obtained may be of potential value, since they represent a first step for engineering a novel 'solid-state' electrode system, of importance for basic and applied biochemistry.This paper reports the electrochemical behaviour, relative to the Fe(III)-Fe(II) conversion, of horseradish peroxidase (HRP) entrapped within a solid matrix, at a pyrolytic graphite electrode. The results indicate that (i) immobilization enhances the electron exchange between the protein and the electrode surface; (ii) reversible electron transfer (eT) is achieved within a wide pH range (pH 3.0-12.0) even in the absence of mediators, (ii) the embedded protein shows native-like structural properties and increased stability. The results obtained may be of potential value, since they represent a first step for engineering a novel `solid-state' electrode system, of importance for basic and applied biochemistry
Preventive Newborn Male Circumcision: What Is the Child's Best Interest?
Full text linkPreventive newborn male circumcision has been at the center of scientific debate for many years. The reason for promoting preventive newborn male circumcision, is the reduction of the incidence of UTIs (in the first six months of life), penile cancer, transmission of STDs/HIV infection/AIDS. However preventive interventions in the newborn involving violations of bodily integrity elicit several ethical questions. In this article, we reviewed the literature regarding circumcision, the prevention of UTIs, penile cancer, transmission of STDs/HIV infection/AIDS and complications of this practice in the neonatal period. The very limited reduction of incidence of UTIs and the uncertain preventive role of newborn male circumcision towards penile cancer, STDs/HIV infection and AIDS, makes it difficult to justify male circumcision in newborns. Moreover, the challenge in obtaining a unanimous opinion on newborn male circumcision derives from the fact that, as a preventive intervention, it requires evaluation criteria that are not comparable to those of therapeutic treatments. Since preventive male circumcision determines permanent alteration of the body, some authors believe that it can be used only in subjects that are capable of giving their valid consent. In the case of a newborn, the ′′child's best interest′′ should be used as a standard, but preventive newborn male circumcision does not satisfy it
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