Biochemical Investigations (biochemical + investigation)

Distribution by Scientific Domains

Selected Abstracts

Physical assessment of patients with anorexia nervosa and bulimia nervosa: an international comparison

D. Kovacs
Abstract Objective: A questionnaire study was carried out to determine which investigations were carried out routinely on patients with anorexia nervosa and bulimia nervosa. Method: A specially designed questionnaire was sent to 168 clinicians working in the field of eating disorders in 25 countries. Respondents were asked to supply information about how often they carry out specific investigations on new patients with AN and BN. The questionnaire covered the use of physical examination, biochemical and haematological tests and cardiac investigations. Results: 71,(42.3,per cent) questionnaires were returned. Biochemical investigations and full blood counts were carried out frequently. Significant differences were found between AN patients and BN patients in the measurement of calcium, phosphate and magnesium levels. In some cases, patients with BN were not routinely assessed for hypokalaemia. Micronutrient levels were measured rarely and only 40,per cent of respondents carried out routine electrocardiograms (ECGs) in AN. Discussion: Measurement of serum potassium should be routine in BN and other electrolytes should probably measured more often in both disorders. Detection of treatable micronutrient deficiencies should be given more emphasis and the ECG should become a routine investigation in AN. Copyright © 2003 John Wiley & Sons, Ltd and Eating Disorders Association. [source]

Progressive neuronal degeneration of childhood: prenatal diagnosis by MRI

Jocelyne de Laveaucoupet
Abstract We report two cases in the same family of progressive neuronal degeneration of childhood,Alpers syndrome,with prenatal MRI findings in one case. The first infant presented at birth with severe microcephaly, then rapidly evolved to progressive encephalopathy with refractory epilepsy, leading to death at 10 months. Biochemical investigations including liver function tests were normal. CT and MRI showed severe diffuse brain atrophy. The diagnosis of progressive neuronal degeneration of childhood was made on the clinical and imaging data. The second pregnancy was marked by gradual decrease of fetal cerebral biometry and a prenatal MRI performed at 32 weeks showed diffuse cortical atrophy, as observed in the sibling. The infant died at 5 months. Neuropathological findings were consistent with Alpers syndrome. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Endocrine Aspects of Sexual Dysfunction in Men

Alvaro Morales MD
ABSTRACT Introduction., Endocrine disorders of sex steroid hormones may adversely affect men's sexual function. Aim., To provide expert opinions/recommendations concerning state-of-the-art knowledge for the pathophysiology, diagnosis and treatment of endocrinologic sexual medicine disorders. Methods., An International Consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five continents developed in a scientific and debate process. Concerning the Endocrine committee, there were eight experts from seven countries. Main Outcome Measure., Expert opinions/recommendations are based on grading of evidence-based medical literature, extensive internal committee discussion over 2 years, public presentation and deliberation. Results., Hypogonadism is a clinical and biochemical syndrome characterized by a deficiency in serum androgen levels which may decrease sexual interest, quality of erections and quality of life. Biochemical investigations include testosterone and either bioavailable or calculated free testosterone; prolactin should be considered when hypogonadism has been documented. If clinically indicated, androgen therapy should maintain testosterone within the physiological range avoiding supraphysiologic values. Digital rectal examination and determination of serum prostate specific antigen values are mandatory prior to therapy and regularly thereafter. Androgen therapy is usually long-term requiring regular follow-up, frequent monitoring of blood levels and beneficial and adverse therapeutic responses. Conclusions., Safe and effective treatments for endocrinologic sexual medicine disorders examined by prospective, placebo-controlled, multi-institutional clinical trials are needed. [source]

Ultrastructural and immunocytochemical characterization of immortalized odontoblast MO6-G3

C. Mesgouez
Abstract Aim, To investigate an immortalized murine odontoblast cell line as a potential alternative for experimental studies on dentinogenesis. Methodology, The MO6-G3 cell line was investigated morphologically over 3, 7, 11 and 42 days of culture, using histochemical localization of dentine sialoprotein (DSP), alkaline phosphatase (AP), type I collagen and actin filaments, histoenzymatic staining and biochemical investigation of AP and finally, transmission and scanning electron microscopy. Results, Scanning electron micrographs showed elongated cells. Accordingly, a polarized organization of odontoblasts was observed by transmission electron microscopy, identifying distinct subcellular compartments as described in vivo. The secretion apparatus, which includes cisternae of rough endoplasmic reticulum, Golgi apparatus saccules and secretion vesicles and granules, was longitudinally organized in the supranuclear compartment ending distally in the secretory pole. A cellular process was observed. The investigation of the cytoskeleton network revealed that actin microfilaments were organized in parallel stress fibre oriented depending on the longitudinal axis of the cytoplasm. Immunofluorescent labelling showed a continuous expression of type I collagen, DSP and AP. A unipolar distribution characterized intracellular DSP immunoreactivity. Histoenzymology revealed AP active sites increasing from 3 to 11 days albeit with a moderate level of activity comparatively to the in vivo situation in dental cells. Conclusion, This cell line MO6-G3 not only showed the criteria of odontoblast phenotype as previously reported but also the characteristic morphodifferentiation pattern of polarized odontoblasts at the cellular level but with an apparent random distribution. [source]

The Effect of Sleep Apnea on QT Interval, QT Dispersion, and Arrhythmias

Kitti Barta MD
Background QT interval (QT) and QT dispersion (QTd) are electrocardiograph (ECG) parameters for the evaluation of myocardial repolarization. The inhomogeneity of ventricular repolarization is associated with ventricular arrhythmias. An increased QT, QTd, and increased incidence of nocturnal cardiac rhythm disturbances have been described in patients with obstructive sleep apnea (OSA), while other investigators did not find a relationship between ventricular arrhythmias and OSA. Hypothesis The aim of this study was to examine the occurrence of ventricular arrhythmias and to measure QT parameters in patients with untreated OSA using an ambulatory Holter-ECG. Methods A total of 25 patients with untreated OSA were studied. After routine biochemical investigation and 2-dimensional, M-mode echocardiography, a 24-hour Holter-ECG was recorded to detect cardiac arrhythmias and QT parameters. QT parameters were measured by the QT Guard system. Results Only the QT interval increased significantly during the nighttime period (nocturnal QT interval: 423.1 ± 34.6 ms, daytime QT interval: 381.6 ± 33.8 ms, 24-hour QT interval: 394.7 ± 31.1 ms). However, during the nighttime QT interval (422.8 ± 14.9 ms), QTd (31.2 ± 11.0 ms) and QT dispersion (30.5 ± 10.2 ms) did not show any change compared to 24-hour (QTc interval: 423.7 ± 14.2 ms, QTd: 28.8 ± 9.4 ms, QTcd: 30.5 ± 9.43 ms) and daytime levels (QTc interval: 423.9 ± 14.3 ms, QTd: 27.3 ± 10.7 ms, QTcd: 29.9 ± 11.1 ms). None of the patients had ventricular arrhythmias. Conclusions QTd and QTcd did not increase during the nighttime period. Our study did not show an increased risk of ventricular arrhythmias in this population during the monitoring period. Copyright © 2010 Wiley Periodicals, Inc. [source]

,Defence lignin' and hydroxycinnamyl alcohol dehydrogenase activities in wounded Eucalyptus gunnii

S. Hawkins
Summary To learn more about lignin formation in response to wounding in trees, we adopted two complementary approaches: (1) microscopic and histochemical studies of the wound response in 3.5-month-old Eucalyptus gunnii plantlets and (2) biochemical investigations of hydroxycinnamyl alcohol dehydrogenase activities in wounded 6-year-old, field-grown E. gunnii trees. The first approach revealed that a barrier zone was formed in response to wounding in both ground tissues (cortex barrier and pith reaction zone) and vascular tissues. The barrier zone was barely detectable after 24 h but well-developed 7 days after wounding. Microscopic analyses indicated that the barrier zone was formed by the reinforcement of cell walls with ,lignin-like material' in both ground tissues and vascular tissue, and that, in addition, the lumen of certain xylem cells (vessels and fibres) were blocked by the deposition of polymeric phenolic material. Histochemical characterization revealed that the lignin-like material (,defence lignin') deposited in ground tissue cell walls and xylem cell blockages was poor in syringyl (S-type) lignin units and therefore differed from the usual mixed guaiacyl,syringyl (G,S) lignin unit composition of E. gunnii developmental lignin. In contrast, S-type lignin appeared to be deposited in the cell walls of immature developing secondary xylem cells at a stage when the cell walls of comparable cells from unwounded control stems contained lignin poor in syringyl units. The second approach indicated that two different types of cinnamyl alcohol dehydrogenase activity are induced, and apparently regulated differentially, in response to wounding in E. gunnii trees. Coniferyl alcohol dehydrogenase activity was induced immediately and continued to increase throughout the first 15 days of the 17-day experimental period, while sinapyl alcohol dehydrogenase activity was first detected at 8 days after wounding and continued to increase throughout the experimental period. The biological roles of the two alcohol dehydrogenase activities are discussed in relation to the formation of defence lignin versus developmental lignin in trees. Résumé Afin d'approfondir nos connaissances concernant la formation de lignine en réponse aux blessures chez les arbres, nous avons utilisé deux approches complémentaires: (1) des études microscopiques et histochimiques de la réponse à la blessure chez les plantules d'Eucalyptus gunniiâgées de 3 mois et demi, et (2) des analyses biochimiques des activités alcools hydroxycinnamyliques déshydrogénases chez les arbres âgés de 6 ans blessés au champ. L'utilization de la première approche a révélé qu'une barrière physique se forme en réponse à la blessure aux niveaux des tissus vasculaires, de la moelle, et des tissus externes au phloème. A 24 h après la blessure, cette barrière est peu développée mais elle est bien formée après 7 jours. Les analyses microscopiques et histochimiques ont indiqué que les parois cellulaires au niveau de la barrière sont renforcées par un composé semblable à la lignine (,lignin-like material'). De plus, les lumens de plusieurs cellules xylémiennes (vaisseaux et fibres) sont bouchées par le dépôt d'un composé polymérique de nature phénolique. Les caractérizations histochimiques ont indiqué que le ,lignin-like material' (lignine de défense) déposé dans les parois cellulaires de la moelle et des tissus externes au phloème, et dans les lumens des cellules xylemiennes, contient peu d'unités syringyles (type-S). En conséquence, cette ,lignine de défense' se distingue de la ,lignine de développement' typique d'E. gunnii, qui est composée d'unités guaiacyles (type-G) et d'unités syringyles (type-S). En revanche chez les plantules blessées, des unités syringyles sont déposées dans les parois des cellules immatures du xylème à un stade où les cellules comparables des plantules témoins ne contiennent que très peu d'unités syringyles. La deuxième approche a indiqué que deux activités alcools cinnamyliques déshydrogénases différentes sont induites, et régulées d'une façon différencielle, en réponse à la blessure chez les arbres d'E. gunnii. L'activité alcool coniférylique déshydrogénase est induite rapidement et continue d'augmenter pendant les 15 premiers jours de la période expérimentale de 17 jours, tandis que l'activité alcool sinapylique déshydrogénase est seulement détectée à 8 jours après la blessure et continue d'augmenter le long de la période expérimentale. Les rôles biologiques potentiels de ces deux activités alcools déshydrogénases sont discutés en relation avec la formation de la lignine de défense et avec la lignine de développement chez les arbres. Zusammenfassung Zur Untersuchung der Ligninbildung nach Verletzungen bei Bäumen wurden zwei sich ergänzende Forschungsansätze gewählt: 1. Mikroskopische und histochemische Untersuchungen der Wundreaktion an Jungpflanzen (3,5 Monate alt) von Eucalyptus gunnii und 2. Biochemische Untersuchungen der Hydroxycinnamylalkohol-Dehydrogenase-Aktivität bei verletzten, sechs Jahre alten E. gunnii -Bäumen im Freiland. Der erste Ansatz zeigte, dass eine Barrierezone als Antwort auf die Verletzung sowohl in beiden Grundgeweben (Cortex-Barriere und Reaktionszone im Mark) als auch in den Leitgeweben gebildet wird. Die Barrierezone war 24 Stunden nach der Verletzung gerade erkennbar, nach sieben Tagen war sie gut entwickelt. Die mikroskopische Untersuchung zeigte, dass die Barrierezone durch Verstärkung der Zellwände mit ,,ligninartigem Material,, im Grund- und Leitgewebe gebildet wurde, und dass zusätzlich das Lumen gewisser Xylemzellen (Gefässe und Fasern) durch Ablagerung von polymerem phenolischem Material verschlossen wurde. Die histochemische Analyse ergab, dass das ligninartige Material (,,Abwehrlignin,,), das in den Zellwänden des Grundgewebes und in den Lumina der Xylemzellen abgelagert wurde, geringe Mengen an Syringyl-(S-Typ)-Lignineinheiten enthielt und sich somit von der normalen Guaiacyl-Syringyl(G-S)-Komposition des Lignins von E. gunnii unterschied. Das S-Typ-Lignin wurde offenbar in den Zellwänden sich entwickelnder sekundärer Xylemzellen abgelagert. Diese Einlagerung erfolgte in einem Stadium, in dem die Zellwände der vergleichbaren Zellen in unverletzten Kontrollstämmen Lignin mit geringem Syringylgehalt enthielten. Der zweite Versuchsansatz zeigte, dass als Reaktion auf die Verletzung zwei verschiedene Arten von Cinnamylalkohol-Dehydrogenase-Aktivitäten induziert und offensichtlich unterschiedlich reguliert werden. Die Aktivität der Coniferyl-Alkohol-Dehydrogenase wurde sofort induziert und sie nahm während 15 Tagen der 17tägigen Versuchsperiode stetig zu, während die Aktivität der Sinapyl-Dehydrogenase erstmals 8 Tage nach der Verletzung nachweisbar war und dann während der gesamten Versuchsperiode anstieg. Die biologische Bedeutung der beiden Alkoholdehydrogenase-Aktivitäten werden in Bezug auf die Bildung von Abwehr-Lignin im Vergleich zur normalen Ligninbildung in Bäumen diskutiert. [source]

Tn5 as a model for understanding DNA transposition

William S. Reznikoff
Summary Tn5 is an excellent model system for understanding the molecular basis of DNA-mediated transposition. Mechanistic information has come from genetic and biochemical investigations of the transposase and its interactions with the recognition DNA sequences at the ends of the transposon. More recently, molecular structure analyses of catalytically active transposase; transposon DNA complexes have provided us with unprecedented insights into this transposition system. Transposase initiates transposition by forming a dimeric transposase, transposon DNA complex. In the context of this complex, the transposase then catalyses four phosphoryl transfer reactions (DNA nicking, DNA hairpin formation, hairpin resolution and strand transfer into target DNA) resulting in the integration of the transposon into its new DNA site. The studies that elucidated these steps also provided important insights into the integration of retroviral genomes into host DNA and the immune system V(D)J joining process. This review will describe the structures and steps involved in Tn5 transposition and point out a biologically important although surprising characteristic of the wild-type Tn5 transposase. Transposase is a very inactive protein. An inactive transposase protein ensures the survival of the host and thus the survival of Tn5. [source]

Biochemical study of resistance to imidacloprid in B biotype Bemisia tabaci from Guatemala

Frank J Byrne
Abstract Systemic uptake bioassays using excised cotton leaves confirmed resistance to imidacloprid in a Guatemalan population of the tobacco whitefly Bemisia tabaci Gennadius. Polyacrylamide gel electrophoresis of naphthyl esterases identified the insects as B-types. Upon collection from the field, resistance was determined to be 58-fold relative to a susceptible strain originating in the Imperial Valley of California. Resistance levels increased to 126-fold in this population during its continuous exposure to systemically treated cotton. In biochemical investigations, there was no detectable NADPH-dependent mixed function oxidase metabolism of 14C-imidacloprid at any time during the selection process. In contrast, microsomal preparations from housefly abdomens readily produced significant amounts of the mono-hydroxy and olefin derivatives of the parent compound. Detoxification of imidacloprid by housefly MFOs may account for reports of lower toxicity of the insecticide towards this insect compared with whiteflies, despite similar binding properties between imidacloprid and the nicotinic acetylcholine receptors in both species. © 2003 Society of Chemical Industry [source]

Isolation of chicken immunoglobulins (IgY) from egg yolk,

J. P. Dean Goldring
Abstract Separating individual proteins from complex mixtures of molecules is the basis of many biochemical investigations. The method describes the separation of immunoglobulin Y (IgY) from chicken eggs using a series of physical and chemical separation techniques. The separation is rapid, and the success of each step is readily viewed on an SDS-polyacrylamide gel. IgY identity can be confirmed on a Western blot probed with enzyme-labeled anti-IgY antibodies. The method is a good illustration of protein separation when there is no enzyme activity to follow. [source]

Genomics of berry fruits antioxidant components

BIOFACTORS, Issue 4 2005
E. D'Amico
Abstract Reactive oxygen and nitrogen metabolites, which are side products of cell metabolism, can produce a lot of damage in biological macromolecules and tissues, producing a number of chronic illnesses. On the other hand, antioxidant metabolites usually accumulated in fruits and vegetables can provide an effective protection by neutralizing these reactive molecules. Among comestible vegetables, berry fruits are considered one of the richest sources of antioxidant metabolites; hence, they represent a good model for molecular and biochemical investigations about the biosynthesis and the functional role of antioxidants in plants. This review illustrates how recent developments in the fields of genomics and bioinformatics can provide powerful tools to better understand the molecular mechanisms that trigger biosynthesis and accumulation of antioxidant metabolites in berries. [source]

There is no clear association between low serum ferritin and chronic diffuse telogen hair loss

R. Sinclair
SummaryBackground Low iron stores are considered a possible cause of chronic diffuse telogen hair loss in women. Estimation of serum ferritin is recommended as part of the initial assessment when women present with chronic diffuse telogen hair loss, and iron supplementation therapy is commonly recommended for those found to have low iron stores. Objectives To evaluate the relationship between low serum ferritin (,20 µg L,1) and chronic diffuse telogen hair loss in women. Methods Between 1997 and 1999, 194 consecutive women who presented to a specialist hair clinic were assessed for diffuse telogen hair loss of greater than 6 months duration. All underwent biochemical investigations that included serum ferritin and had two 4-mm punch biopsies taken from the vertex of the scalp. One biopsy was sectioned horizontally and the other vertically. Results Twelve women were found to have a serum ferritin of 20 µg L,1 or less (6·2%). Androgenetic alopecia was found on scalp biopsy in seven of these 12 women, while the other five women had normal histology. The five women with low iron stores and normal histology were treated with iron supplementation alone. This was continued until the serum ferritin was > 20 µg L,1. Cessation or reversal of hair loss was not seen in any of these women. Conclusions No direct relationship between low serum ferritin and hair loss can be established. The usefulness of serum ferritin in the routine investigation of women with chronic diffuse telogen hair loss is unclear, as is the role of iron supplementation therapy in the management of hair loss. [source]

Structure, biological activity and membrane partitioning of analogs of the isoprenylated a -factor mating peptide of Saccharomyces cerevisiae

H. Xie
Abstract: Previous biochemical investigations on the Saccharomyces cerevisiaea -factor indicated that this lipopeptide pheromone [YIIKGVFWDPAC(farnesyl)OMe] might adopt a type II ,-turn at positions 4 and 5 of the peptide sequence. To test this hypothesis, we synthesized five analogs of a -factor, in which residues at positions 4 and 5 were replaced with: l -Pro4(I); d -Pro4(II); l -Pro4 - d -Ala5(III); d - Pro4 - l -Ala5(IV); or Nle4(V). Analogs were purified to > 99% homogeneity as evidenced by HPLC and TLC and were characterized by mass spectrometry and amino acid analysis. Using a growth arrest assay the conformationally restricted a -factor analogs I and III were found to be almost 50-fold more active than the diastereometric homologs II and IV and were equally active to wild-type a -factor. Replacement of Lys4 with the isosteric Nle4 almost abolished the activity of the pheromone. Thus, the incorporation of residues that promote a type II ,-turn compensated for the loss of the favorable contribution of the Lys4 side chain to pheromone activity. CD spectra on these peptides suggested that they were essentially disordered in both TFE/H2O and in the presence of DMPC vesicles. There was no correlation between CD peak shape and biological activity. Using fluorescence spectroscopy we measured the interaction of lipid vesicles with these position 4 and 5 analogs as well as with three a -factor analogs with a modified farnesyl group. The results indicated that modifications of both the peptide sequence and the lipid moiety affect partitioning into lipid, and that no correlation existed between the propensity of a pheromone to partition into the lipid and its biological activity. [source]