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Several Weeks (several + week)
Selected AbstractsDisturbance history influences the distribution of stream invertebrates by altering microhabitat parameters: a field experimentFRESHWATER BIOLOGY, Issue 5 2008MICHAEL EFFENBERGER Summary 1. We investigated the effects of local disturbance history and several biotic and abiotic habitat parameters on the microdistribution of benthic invertebrates after an experimental disturbance in a flood-prone German stream. 2. Bed movement patterns during a moderate flood were simulated by scouring and filling stream bed patches (area 0.49 m2) to a depth of 15,20 cm. Invertebrates were investigated using ceramic tiles as standardized substrata. After 1, 8, 22, 29, 36 and 50 days, we sampled one tile from each of 16 replicates of three bed stability treatments (scour, fill and stable controls). For each tile, we also determined water depth, near-bed current velocity, the grain size of the substratum beneath the tile, epilithic algal biomass and standing stock of particulate organic matter (POM). 3. Shortly after disturbance, total invertebrate density, taxon richness and density of the common taxa Baetis spp. and Chironomidae were highest in stable patches. Several weeks after disturbance, by contrast, Baetis spp. and Hydropsychidae were most common in fill and Leuctra spp. in scour patches. The black fly Simulium spp. was most abundant in fill patches from the first day onwards. Community evenness was highest in scour patches during the entire study. 4. Local disturbance history also influenced algal biomass and POM standing stock at the beginning of the experiment, and water depth, current velocity and substratum grain size throughout the experiment. Scouring mainly exposed finer substrata and caused local depressions in the stream bed characterized by slower near-bed current velocity. Algal biomass was higher in stable and scour patches and POM was highest in scour patches. In turn, all five common invertebrate taxa were frequently correlated with one or two of these habitat parameters. 5. Our results suggest that several ,direct' initial effects of local disturbance history on the invertebrates were subsequently replaced by ,indirect' effects of disturbance history (via disturbance-induced changes in habitat parameters such as current velocity or food). [source] Adenosine reverses a preestablished CCl4 -induced micronodular cirrhosis through enhancing collagenolytic activity and stimulating hepatocyte cell proliferation in ratsHEPATOLOGY, Issue 4 2001Rolando Hernández-Muñoz Cirrhosis is one of the most common causes of mortality worldwide, because hepatic dysfunction constitutes a potentially lethal condition. Having demonstrated the hepatoprotective effect of adenosine against CCl4 -induced cirrhosis, the present study was aimed at assessing adenosine's effect on an already-established micronodular cirrhosis. Chronic administration of CCl4 (10 weeks) induced a cirrhotic state, characterized by increased liver fibronectin and collagen types I and III content, enhanced expression of ,-1 (I) collagen mRNA, portal hypertension, and liver dysfunction. After CCl4 discontinuation (5 weeks), increased persitance of ,-1 (I) collagen mRNA expression and deposition, enhanced proline incorporation into collagen and prolyl hydroxylase activity evidenced active fibrogenesis. Several weeks after CCl4 withdrawal, deposited collagen showed an enhanced type I/III ratio, which was associated with deficient collagenolytic activity in cirrhotic livers. Liver expression of some metalloproteinases (MMPs) and of tissue inhibitors of MMPs (TIMPs) also indicated decreased collagen breakdown in cirrhotic livers. Parameters indicative of oxidative stress (mainly protein oxidation) were persistently augmented. These events were coincident with diminished regenerative capacity of the cirrhotic liver. Intraperitoneal adenosine administration to CCl4 -induced cirrhotic rats blocked active fibrogenesis and increased the collagen degradation (most probably by decreasing liver TIMPs levels), normalizing collagen-type ratios. In addition, the nucleoside promoted an effective hepatocyte's proliferation in the cirrhotic liver and accelerated normalization of parameters indicative of liver function and oxidative stress. Thus, adenosine readily reversed an experimental cirrhosis through stimulating liver collagenolytic and proliferative capacities, as well as by accelerating functional recovery. [source] Towards development of a nonhuman primate model of carpal tunnel syndrome: Performance of a voluntary, repetitive pinching task induces median mononeuropathy in Macaca fascicularisJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2007Carolyn M. Sommerich Abstract This study investigated changes in median sensory nerve conduction velocity (SNCV) over several weeks of exposure to a voluntary, moderately forceful, repetitive pinching task performed for food rewards by a small sample of young adult female monkeys (Macaca fascicularis). SNCV, derived from peak latency, decreased significantly in the working hands of three of the four subjects. The overall decline in NCV was 25%,31% from baseline. There was no decrease in SNCV in the contralateral, nonworking hands. Several weeks after being removed from the task, SNCV returned to within 87%,100% of baseline. MRI showed enlargement of the affected nerves near the proximal end of the carpal tunnel, at the time of maximal SNCV slowing. This new animal model demonstrates a temporally unambiguous relationship between exposure to a moderately forceful, repetitive manual task and development of median mononeuropathy at the wrist, and recovery of SNCV following termination of task exposure. This study contributes to the pattern of evidence of a causal relationship between manual work, median mononeuropathy, and carpal tunnel syndrome in humans. In the future, this new animal model could be used to characterize dose,response relationships between risk factors and carpal tunnel syndrome. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25: 713,724, 2007 [source] Refractory Progression of Coronary Aneurysms, a Case of Delayed Onset Kawasaki Disease as Depicted by Cardiac Computed Tomography AngiographyCONGENITAL HEART DISEASE, Issue 3 2010FACP, Shah Azmoon MD ABSTRACT Background., Kawasaki disease (KD) is an immune-mediated vasculitis of unknown etiology with self-limited clinical course that was first described in 1967 by Dr. Tomisaku Kawasaki. It is a disease of early childhood and rare past late adulthood but one that can have detrimental consequences when there is a delay in diagnosis and treatment. Cardiovascular complications causing increased morbidity and mortality may include coronary artery aneurysms, myocardial infarction, heart failure, arrhythmias, and peripheral artery occlusion. Case Presentation., Here, we present an atypical case of delayed onset KD in a young teenager. DS had visited three different emergency departments during the course of 2 weeks for unrelenting fevers. Despite multiple treatment protocols including immunoglobulin, steroids, and tumor necrosis factor-alpha antagonists, he continued to have progression of cardiovascular complications. While echocardiographic findings were suspicious for cardiac complications, a cardiac computed tomography (CT) angiography was able to clearly distinguish giant coronary aneurysms. Conclusion., Without prompt therapy, fever and manifestations of acute inflammation can last for several weeks to months with increased risk toward complications. The incidence of coronary artery aneurysms has been noted to be 25% in untreated patients with a mortality rate of up to 2%. Using low-dose protocols along with high spatial and temporal resolution of cardiac CT angiography may provide a useful and complimentary imaging modality in accurate diagnosis and follow-up of patients with KD. [source] The role of intramuscular lipid in insulin resistanceACTA PHYSIOLOGICA, Issue 4 2003B. D. Hegarty Abstract There is interest in how altered lipid metabolism could contribute to muscle insulin resistance. Many animal and human states of insulin resistance have increased muscle triglyceride content, and there are now plausible mechanistic links between muscle lipid accumulation and insulin resistance, which go beyond the classic glucose,fatty acid cycle. We postulate that muscle cytosolic accumulation of the metabolically active long-chain fatty acyl CoAs (LCACoA) is involved, leading to insulin resistance and impaired insulin signalling or impaired enzyme activity (e.g. glycogen synthase or hexokinase) either directly or via chronic translocation/activation of mediators such as a protein kinase C (particularly PKC , and ,). Ceramides and diacylglycerols (DAGs) have also been implicated in forms of lipid-induced muscle insulin resistance. Dietary lipid-induced muscle insulin resistance in rodents is relatively easily reversed by manipulations that lessen cytosolic lipid accumulation (e.g. diet change, exercise or fasting). PPAR agonists (both , and ,) also lower muscle LCACoA and enhance insulin sensitivity. Activation of AMP-activated protein kinase (AMPK) by AICAR leads to muscle enhancement (especially glycolytic muscle) of insulin sensitivity, but involvement of altered lipid metabolism is less clear cut. In rodents there are similarities in the pattern of muscle lipid accumulation/PKC translocation/altered insulin signalling/insulin resistance inducible by 3,5-h acute free fatty acid elevation, 1,4 days intravenous glucose infusion or several weeks of high-fat feeding. Recent studies extend findings and show relevance to humans. Muscle cytosolic lipids may accumulate either by increased fatty acid flux into muscle, or by reduced fatty acid oxidation. In some circumstances muscle insulin resistance may be an adaptation to optimize use of fatty acids when they are the predominant available energy fuel. The interactions described here are fundamental to optimizing therapy of insulin resistance based on alterations in muscle lipid metabolism. [source] Postembryonic development of the cranial lateral line canals and neuromasts in zebrafishDEVELOPMENTAL DYNAMICS, Issue 3 2003Jacqueline F. Webb Abstract The development of the cranial lateral line canals and neuromast organs are described in postembryonic zebrafish (0,80 days postfertilization). Cranial canal development commences several weeks after hatch, is initiated in the vicinity of individual neuromasts, and occurs in four discrete stages that are described histologically. Neuromasts remain in open canal grooves for several weeks during which they dramatically change shape and increase in size by adding hair cells at a rate one-tenth that in the zebrafish inner ear. Scanning electron microscopy demonstrates that neuromasts elongate perpendicular to the canal axis and the axis of hair cell polarization and that they lack a prominent nonsensory cell population surrounding the hair cells,features that make zebrafish neuromasts unusual among fishes. These results demand a reassessment of neuromast and lateral line canal diversity among fishes and highlight the utility of the lateral line system of postembryonic zebrafish for experimental and genetic studies of the development and growth of hair cell epithelia. Developmental Dynamics, 2003. © 2003 Wiley-Liss, Inc. [source] Withdrawal symptoms in abstinent methamphetamine-dependent subjectsADDICTION, Issue 10 2010Todd Zorick ABSTRACT Aims Withdrawal symptoms have been linked to a propensity for relapse to drug abuse. Inasmuch as this association applies to methamphetamine (MA) abuse, an understanding of the course of MA withdrawal symptoms may help to direct treatment for MA dependence. Previous studies of symptoms manifested during abstinence from MA have been limited in size and scope. We asked (i) whether debilitating psychological and/or physical symptoms appear during the first several weeks of MA abstinence, (ii) how craving for MA evolves and (iii) whether psychiatric symptoms (e.g. depression, psychosis) persist beyond a month of abstinence. Design A study of MA-dependent participants, who initiated and maintained abstinence from the drug for up to 5 weeks, compared to a matched healthy comparison group. Setting In-patient research hospital ward (MA-dependent subjects) and out-patient (comparison subjects). Participants Fifty-six MA-dependent and eighty-nine comparison subjects. Measurements Rater-assessed MA withdrawal questionnaire and self-report assessment of craving (MA-dependent subjects) and self-report assessment of psychiatric symptoms (both groups). Findings At study entry, MA-dependent subjects exhibited a wide range in severity of depressive symptoms, with the average score at a mild,moderate level of severity. Symptoms of psychosis were also prevalent. While depressive and psychotic symptoms largely resolved within a week of abstinence, craving did not decrease significantly from the time of initiating abstinence until the second week, and then continued at a reduced level to the fifth week. Conclusions Depressive and psychotic symptoms accompany acute withdrawal from methamphetamine but resolve within 1 week. Craving is also present and lasts at least 5 weeks. [source] Course of Intraatrial Thrombi Resolution Using Transesophageal EchocardiographyECHOCARDIOGRAPHY, Issue 2 2003Jennifer A. Larsen M.D. Thromboembolic events are associated with atrial fibrillation and with cardioversion to sinus rhythm. Although studies have demonstrated the risk of this complication is reduced by a 3-week period of anticoagulation prior to cardioversion, limited data have suggested a longer period of anticoagulation is necessary for thrombus resolution. We identified and followed 25 patients noted to have intraatrial thrombi on an initial transesophageal echocardiogram (TEE) who subsequently had a follow-up TEE. The majority of patients had a single thrombus, often but not uniformly located in the left atrial appendage with the largest found in those patients with mitral stenosis. Repeat TEE was performed at a mean of 4 ± 6 months and persistent thrombus was noted in 19 of 25 patients (76%). Seven of 19 patients with persistent thrombi were cardioverted and one of these patients had a neurologic event following the procedure (14%). The only findings associated with persistent thrombus were the presence of mitral valve disease and atrial fibrillation.. Our findings suggest that intraatrial thrombi do not generally resolve following several weeks of anticoagulation and that persistent left-sided intraatrial thrombi may be associated with an increased risk for events following cardioversion. Given that a TEE-guided approach to cardioversion is being utilized more frequently, it may be important to determine thrombus characteristics on follow-up that would be predictive of embolic events following cardioversion. (ECHOCARDIOGRAPHY, Volume 20, February 2003) [source] Amalgam Electrodes for ElectroanalysisELECTROANALYSIS, Issue 8 2003Øyvind Mikkelsen Abstract Liquid mercury is a unique material for the indicator electrode in voltammetry. One reason for this is the high overvoltage for hydrogen formation, thus extending the actual potential window. Diluted amalgams are important reaction products in voltammetric (polarographic) processes, however liquid amalgams are rarely used directly as electrode material for analytical purposes. Because of the fact that voltammetry is very suitable for field and remote monitoring, issues concerning the use of mercury electrodes in environmental analyses have led to considerable research effort aimed at finding alternative tools with acceptable performance. Solid electrodes are such alternatives. Different types of electrodes are reviewed. In particular, solid amalgam electrodes are very promising, with acceptable low toxicity to be used for field measurements. Solid amalgam electrodes are easy and cheap to construct and are stable over a reasonable time up to several weeks. Assessment of the toxicity risk and the long time stability for remote and unattended monitoring is discussed. The differences between solid dental amalgam electrodes, made by using techniques known from dental clinical practice, and mercury film or mercury layer electrodes on solid substrates are reviewed. In particular the dental technique for constructing solid amalgam electrodes gives advantage because it's fast and inexpensive. Also the technique for making dental amalgam has been explored and optimized over years by dentists, giving advantage when the same technique is used for constructing electrodes. Dental amalgam electrodes has been found to act similar to a silver electrodes, but with high overvoltage towards hydrogen. This make it possible to use the dental amalgam electrode for detection of zinc, cobalt and nickel in additions to other metals like lead, copper, thallium, cadmium, bismuth, iron etc. Also the use for reducible organic compounds is expected to be promising. [source] Application of Exchangeable Biochemical Reactors with Oxidase-Catalase-Co-immobilizates and Immobilized Microorganisms in a Microfluidic Chip-CalorimeterENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2008M. Leifheit Abstract Several methods for the quantitative detection of different compounds, e.g., L -amino acids, sugars or alcohols in liquid media were developed by application of an automatic measuring unit including a fluid chip-calorimeter FCC-21. For this purpose, enzymes were immobilized covalently on the inner and outer surface of CPG (controlled porous glass)-spherules with an outer diameter of 100,,m and filled into a micro flow-through reaction chamber (VR = 20,,L). The design of the measuring cell allows for easy insertion into the calorimeter device of a stored series of comfortably pre-fabricated measuring cells. These cells can be filled with different enzyme immobilizates. Different oxidases were used and co-immobilized with catalase for the improvement of the detection sensitivity. A signal amplification could be achieved up to a factor of 3.5 with this configuration. ,- D -glucose, ethanol and L -lysine could be detected in a range of 0.25,1.75,mM using glucose oxidase, alcohol oxidase and lysine oxidase. The group of oxidases in combination with the enzymatic catalysis of the intermediate H2O2 allows the quantitative detection of a large number of analytes. A good measurement and storage stability could be achieved for several weeks by this immobilization method. In addition to enzyme-based detection reactions, it was shown that living microorganisms can be immobilized in the reaction chamber. Thus, the system can be used as a whole-cell biosensor. The quantitative detection of phenol in the range of 10,100,,M could be performed using the actinomycete Rhodococcus sp. immobilized on glass beads by means of embedding into polymers. [source] The obligate aerobic actinomycete Streptomyces coelicolor A3(2) survives extended periods of anaerobic stressENVIRONMENTAL MICROBIOLOGY, Issue 12 2007Geertje Van Keulen Summary The actinomycete Streptomyces coelicolor is an obligate aerobe that is found in soil and aqueous habitats. The levels of oxygen in these environments can vary considerably, which raises the question of how these bacteria survive during periods of anaerobiosis. Although S. coelicolor cannot grow in the complete absence of oxygen, we demonstrate here that it is capable of microaerobic growth and maintaining viability through several weeks of strict anaerobiosis. Both resting and germinated spores are able to survive abrupt exposure to anaerobiosis, which contrasts the situation with Mycobacterium species where gradual oxygen depletion is required to establish a latent state in which the bacterium is able to survive extended periods of anaerobiosis. Growth of S. coelicolor resumes immediately upon re-introduction of oxygen. Taken together these findings indicate that survival is not restricted to spores and suggest that the bacterium has evolved a mechanism to maintain viability and a membrane potential in the hyphal state. Furthermore, although we demonstrate that several members of the genus also survive long periods of anaerobic stress, one species, Streptomyces avermitilis, does not have this capacity and might represent a naturally occurring variant that is unable to adopt this survival strategy. [source] Effects of handling on heat shock protein expression in rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002Barbara Shayne Washburn Abstract As part of an effort to validate the use of heat shock proteins (HSPs) as biomarkers of exposure to and effects of contaminants, we evaluated the effect of two handling regimens on the induction of HSP 60 and 70 in rainbow trout (Oncorhynchus mykiss). Fish were acclimated to laboratory conditions for several weeks before the beginning of the experiment. Fish were then captured by net, placed in a cooler for 1 h while being transported in a truck, returned to their original tanks, then sacrificed 6 to 8 h later. Tricaine methane sulfonate (MS-222) was used during different phases of handling to reduce handling stress. Heat-stressed fish were included in the experiment as a positive control. Muscle, liver, gills, and heart were analyzed for HSP 60 and 70 by immunoblotting. We found no effect of any handling regimen on the induction of HSPs. These findings suggest that the capture and transport of fish for environmental monitoring purposes should not interfere with the use of stress proteins as biomarkers. [source] Prevention of diabetes in NOD mice at a late stage by targeting OX40/OX40 ligand interactionsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 11 2004Syamasundar Abstract Autoreactive T,cells play a major role in the development of insulin-dependent diabetes mellitus, suggesting that costimulatory molecules that regulate T,cell responses might be essential for disease progression. In NOD mice, CD28/B7 and CD40/CD40 ligand,(L) interactions control the onset of diabetes from 2 to 4,weeks of age, but blocking these molecules has little effect after this time. Hence, it is possible that other ligand/receptor pairs control a later phase of disease. We now show that OX40 is expressed on CD4 and CD8 T,cells several weeks prior to islet destruction, which is initiated around weeks,12,14, and that OX40L is present on dendritic cells in both secondary lymphoid organs and the pancreas from 11 to 13,weeks of age. Blocking OX40L at 6, 9, or 15,weeks after birth had little effect on disease; however, inhibiting OX40/OX40L interactions at week,12, or continuous treatment from week,12 onwards, significantly reduced the incidence of diabetes. Histological examination showed that islet destruction was prevented and insulitis reduced by targeting OX40L. These studies show that OX40/OX40L interactions form a late checkpoint in diabetes development and suggest that these molecules are realistic targets for therapeutic intervention. [source] Alcohol self-administration acutely stimulates the hypothalamic-pituitary-adrenal axis, but alcohol dependence leads to a dampened neuroendocrine stateEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2008Heather N. Richardson Abstract Clinical studies link disruption of the neuroendocrine stress system with alcoholism, but remaining unknown is whether functional differences in the hypothalamic-pituitary-adrenal (HPA) axis precede alcohol abuse and dependence or result from chronic exposure to this drug. Using an operant self-administration animal model of alcohol dependence and serial blood sampling, we show that long-term exposure to alcohol causes significant impairment of HPA function in adult male Wistar rats. Acute alcohol (voluntary self-administration or experimenter-administered) stimulated the release of corticosterone and its upstream regulator, adrenocorticotropic hormone, but chronic exposure sufficient to produce dependence led to a dampened neuroendocrine state. HPA responses to alcohol were most robust in ,low-responding' non-dependent animals (averaging < 0.2 mg/kg/session), intermediate in non-dependent animals (averaging ,0.4 mg/kg/session), and most blunted in dependent animals (averaging ,1.0 mg/kg/session) following several weeks of daily 30-min self-administration sessions, suggesting that neuroendocrine tolerance can be initiated prior to dependence and relates to the amount of alcohol consumed. Decreased expression of corticotropin-releasing factor (CRF) mRNA expression in the paraventricular nucleus of the hypothalamus and reduced sensitivity of the pituitary to CRF may contribute to, but do not completely explain, neuroendocrine tolerance. The present results, combined with previous studies, suggest that multiple adaptations to stress regulatory systems may be brought about by excessive drinking, including a compromised hormonal response and a sensitized brain stress response that together contribute to dependence. [source] Spectro-temporal sound density-dependent long-term adaptation in cat primary auditory cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2008Boris Gourévitch Abstract Sensory systems use adaptive strategies to code for the changing environment on different time scales. Short-term adaptation (up to 100 ms) reflects mostly synaptic suppression mechanisms after response to a stimulus. Long-term adaptation (up to a few seconds) is reflected in the habituation of neuronal responses to constant stimuli. Very long-term adaptation (several weeks) can lead to plastic changes in the cortex, most often facilitated during early development, by stimulus relevance or by behavioral states such as attention. In this study, we show that long-term adaptation with a time course of tens of minutes is detectable in anesthetized adult cat auditory cortex after a few minutes of listening to random-frequency tone pips. After the initial post-onset suppression, a slow recovery of the neuronal response strength to tones at or near their best frequency was observed for low-rate random sounds (four pips per octave per second) during stimulation. The firing rate at the end of stimulation (15 min) reached levels close to that observed during the initial onset response. The effect, visible for both spikes and, to a smaller extent, local field potentials, decreased with increasing spectro-temporal density of the sound. The spectro-temporal density of sound may therefore be of particular relevance in cortical processing. Our findings suggest that low stimulus rates may produce a specific acoustic environment that shapes the primary auditory cortex through very different processing than for spectro-temporally more dense and complex sounds. [source] Diffusion of strongly sorbed solutes in soil: a dual-porosity model allowing for slow access to sorption sites and time-dependent sorption reactionsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2010M. Ptashnyk We use homogenization techniques to derive a dual (or double) porosity model of solute diffusion and reaction in soil, allowing for slow access to sorption sites within micro-aggregates and time-dependent sorption reactions. We give a means for determining the conditions in which micro-scale concentration gradients affect macro-scale gradients and fluxes. We present equations for a unit volume of soil represented as a series of uniformly-spaced, porous spherical particles, containing and surrounded by solution through which solutes diffuse. The methods we use can, in principle, be applied to more complex geometries. We compare the model's predictions with those of the equivalent single porosity model for commonly used boundary conditions. We show that failure to allow for slow access to reaction sites can lead to seriously erroneous results. Slow access has the effect of decreasing the sorption of solute into soil from a source or desorption from soil to a sink. As a result of slow access, the diffusion coefficients of strongly-sorbed solutes measured at the macro-scale will be time-dependent and will depend on the method of measurement. We also show that slow access is more often likely to limit macro-scale diffusion than rates of slow chemical reactions per se. In principle, the unimportance of slow reactions except at periods longer than several weeks of diffusion simplifies modelling because, if slow access is correctly allowed for, sorption can be described with equilibrium relations with an understanding of speciation and rapid sorption-desorption reactions. [source] Hyperefficient PrPSc amplification of mouse-adapted BSE and scrapie strain by protein misfolding cyclic amplification techniqueFEBS JOURNAL, Issue 10 2009Aiko Fujihara Abnormal forms of prion protein (PrPSc) accumulate via structural conversion of normal PrP (PrPC) in the progression of transmissible spongiform encephalopathy. Under cell-free conditions, the process can be efficiently replicated using in vitro PrPSc amplification methods, including protein misfolding cyclic amplification. These methods enable ultrasensitive detection of PrPSc; however, there remain difficulties in utilizing them in practice. For example, to date, several rounds of protein misfolding cyclic amplification have been necessary to reach maximal sensitivity, which not only take several weeks, but also result in an increased risk of contamination. In this study, we sought to further promote the rate of PrPSc amplification in the protein misfolding cyclic amplification technique using mouse transmissible spongiform encephalopathy models infected with either mouse-adapted bovine spongiform encephalopathy or mouse-adapted scrapie, Chandler strain. Here, we demonstrate that appropriate regulation of sonication dramatically accelerates PrPSc amplification in both strains. In fact, we reached maximum sensitivity, allowing the ultrasensitive detection of < 1 LD50 of PrPSc in the diluted brain homogenates, after only one or two reaction rounds, and in addition, we detected PrPSc in the plasma of mouse-adapted bovine spongiform encephalopathy-infected mice. We believe that these results will advance the establishment of a fast, ultrasensitive diagnostic test for transmissible spongiform encephalopathies. [source] Modulation of oat arginine decarboxylase gene expression and genome organization in transgenic Trypanosoma cruzi epimastigotesFEBS JOURNAL, Issue 3 2006María P. Serra We have previously demonstrated that wild-type Trypanosoma cruzi epimastigotes lack arginine decarboxylase (ADC) enzymatic activity as well as its encoding gene. A foreign ADC has recently been expressed in T. cruzi after transformation with a recombinant plasmid containing the complete coding region of the oat ADC gene. In the present study, upon modulation of exogenous ADC expression, we found that ADC activity was detected early after transfection; subsequently it decreased to negligible levels between 2 and 3 weeks after electroporation and was again detected ,,4 weeks after electroporation. After this period, the ADC activity increased markedly and became expressed permanently. These changes of enzymatic activity showed a close correlation with the corresponding levels of ADC transcripts. To investigate whether the genome organization of the transgenic T. cruzi underwent any modification related to the expression of the heterologous gene, we performed PCR amplification assays, restriction mapping and pulse-field gel electrophoresis with DNA samples or chromosomes obtained from parasites collected at different time-points after transfection. The results indicated that the transforming plasmid remained as free episomes during the transient expression of the foreign gene. Afterwards, the free plasmid disappeared almost completely for several weeks and, finally, when the expression of the ADC gene became stable, two or more copies of the transforming plasmid arranged in tandem were integrated into a parasite chromosome (1.4 Mbp) bearing a ribosomal RNA locus. The sensitivity of transcription to ,-amanitin strongly suggests involvement of the protozoan RNA polymerase I in the transcription of the exogenous ADC gene. [source] Timing of spawning and glochidial release in Scottish freshwater pearl mussel (Margaritifera margaritifera) populationsFRESHWATER BIOLOGY, Issue 12 2003Lee C. Hastie Summary 1. The timing of reproduction was investigated in six Scottish freshwater pearl mussel populations from 1993 to 2002. Gravid females were examined and the release of mussel larvae (glochidia) was monitored. 2. Annual spawning (oviposition) and spat (glochidial release) events occurred during June to July and June to September, respectively. 3. Between-river differences in timing seem to be related to water temperature. Mussels in the warmest rivers tend to spawn and spat first, and vice-versa. 4. Thermal variations also seem to influence the timing of reproduction within rivers, which can be delayed by several weeks during cold years. At least 3000°-days occur between annual episodes of glochidial release. 5. The timing of spawning is determined gradually, probably by a thermal summation effect. 6. The release stage occurs as a sudden, synchronised event, with most of the glochidia spat over 1,2 days, indicating that it is triggered by an environmental cue. Sudden changes in water temperature and/or river level often result in spats, and the underlying mechanism may be respiratory. [source] Characterizing nitrogen dynamics, retention and transport in a tropical rainforest stream using an in situ15N additionFRESHWATER BIOLOGY, Issue 1 2002Jeffrey L. Merriam 1.,This study was part of the Lotic Intersite Nitrogen eXperiment (LINX); a series of identical 15NH4 tracer additions to streams throughout North America. 15NH4Cl was added at tracer levels to a Puerto Rican stream for 42 days. Throughout the addition, and for several weeks afterwards, samples were collected to determine the uptake, retention and transformation pathways of nitrogen in the stream. 2.,Ammonium uptake was very rapid. Nitrification was immediate, and was a very significant transformation pathway, accounting for over 50% of total NH4 uptake. The large fraction of NH4 uptake accounted for by nitrification (a process that provides energy to the microbes involved) suggests that energy limitation of net primary production, rather than N limitation, drives N dynamics in this stream. 3.,There was a slightly increased 15N label in dissolved organic nitrogen (DON) the day after the 15NH4 addition was stopped. This DO15N was < 0.02% of DON concentration in the stream water at the time, suggesting that nearly all of the DON found in-stream is allochthonous, or that in-stream DON production is very slow. 4.,Leptophlebiidae and Atya appear to be selectively feeding or selectively assimilating a very highly labelled fraction of the epilithon, as the label found in the consumers became much higher than the label found in the food source. 5.,A large spate (>20-fold increase in discharge) surprisingly removed only 37% of in-stream fine benthic organic matter (FBOM), leaves and epilithon. The fraction that was washed out travelled downstream a long distance (>220 m) or was washed onto the stream banks. 6.,While uptake of 15NH4 was very rapid, retention was low. Quebrada Bisley retained only 17.9% of the added 15N after 42 days of 15N addition. Most of this was in FBOM and epilithon. Turnover rates for these pools were about 3 weeks. The short turnover times of the primary retention pools suggest that long-term retention (>1 month) is minimal, and is probably the result of N incorporation into shrimp biomass, which accounted for < 1% of the added 15N. [source] In vivo observation of the locomotion of microglial cells in the retinaGLIA, Issue 14 2010Michel Paques Abstract Microglial cells (MCs) are active sensors and reactive phagocytes of neural tissues. They are known to migrate and accumulate in areas of neuronal damage. Thus, microglial locomotion is an essential feature of the inflammatory reaction in neural tissue. Yet, to our knowledge there has been no report of direct in vivo observation of the migration of MCs. Here, we show that intravitreally injected cyanine dyes (DiO, DiI, and indocyanine green) are sequestrated in MCs during several months, and subsequently in vivo images of these fluorescent MCs can be obtained by confocal scanning laser ophthalmoscopy. This enabled noninvasive, time-lapse observation of the migrating behavior of MCs, both in the basal state and following laser damage. In the basal state, a slow, intermittent, random-like locomotion was observed. Following focal laser damage, MCs promptly (i.e., within 1 h) initiated centripetal, convergent migration. MCs up to 400 ,m away migrated into the scar at velocities up to 7 ,m/min. This early phase of centripetal migration was followed by a more prolonged phase of nontargeted locomotion around and within injured sites during at least 24 h. Cyanine-positive cells persisted within the scar during several weeks. To our knowledge, this is the first in vivo observation of the locomotion of individual MCs. Our results show that the locomotion of MCs is not limited to translocation to acutely damaged area, but may also be observed in the basal state and after completion of the recruitment of MCs into scars. © 2010 Wiley-Liss, Inc. [source] Considerations in the evaluation of haemophilia patients for short-term prophylactic therapy: a paediatric and adult case studyHAEMOPHILIA, Issue 1 2006L. LUCHTMAN-JONES Summary., The long-term prophylactic administration of clotting factor concentrate in patients with haemophilia reduces bleeding events, slows joint deterioration, and improves quality of life. Prophylaxis can also be effective when used short-term to prevent or reduce bleeding associated with trauma, surgery, and athletic activities. While clinical trials are needed to establish the optimal length of prophylaxis following injury, several weeks and possibly months of treatment may be needed. Discontinuing therapy prematurely can result in rebleeding in the injured area. [source] Bell's palsy during interferon therapy for chronic hepatitis C infection in patients with haemorrhagic disordersHAEMOPHILIA, Issue 2 2000Ogundipe Two adult patients with life-long severe haemorrhagic disorders commenced on interferon-,2b therapy for chronic hepatitis C infection. Both developed Bell's palsy several weeks after commencing therapy, They were started on steroids and, in addition, the first patient discontinued interferon-,2b therapy while the second patient elected to continue with therapy. In both cases facial paralysis improved over the ensuing weeks. Bell's palsy is often idiopathic but has been reported. in association with herpesviruses. It is not a recognised complication of chronic hepatitis B or C infection, or interferon-,2b therapy. However, the interferons are associated with numerous adverse reactions including various neuropsychiatric manifestations and neurological syndromes. There are several reports of nerve palsies, including optic tract neuropathy, occurring during interferon therapy, and immune-based mechanisms are thought to play a role in the aetiopathogenesis. No reports of Bell's palsy in association with interferon therapy were identified in our literature search, although one possible case has been reported to the Committee of Safety in Medicine. Although Bell's palsy in our patients may have occurred by chance, a neuropathic effect of interferon-,2b on the facial nerve cannot be excluded and we urge physicians using interferons to be aware of this potential side-effect. [source] Orthostatic Headaches in the Syndrome of the Trephined: Resolution Following CranioplastyHEADACHE, Issue 7 2010Bahram Mokri MD Objective., To draw attention to the syndrome of the trephined as a potential cause for orthostatic headaches without cerebrospinal fluid (CSF) leak. Background., Orthostatic headaches typically result from CSF leaks but sometimes may occur in conditions without any evidence of CSF leakage. Methods., A 37-year-old right-handed woman became comatose after a motor vehicle accident with cerebral contusions and massive left cerebral edema. A large frontoparietal craniectomy was carried out. In 5 months, she made good neurologic recovery. Freeze-preserved bone flap was placed back. In several weeks she was functionally near normal. Two years later, she began to complain of orthostatic headache and gradually additional manifestations appeared including progressive gait unsteadiness, imprecise speech, cognitive difficulties, and an increasing left hemiparesis along with progressive sinking of the skull defect and shift of the midline and ventricular distortion. She underwent removal of resorptive sinking bone flap and construction of an acrylic cranioplasty. Results., At 6-month follow-up, there was complete resolution of the orthostatic headaches, remarkable neurologic improvement along with resolution of midline shift and ventricular distortion. Conclusion., The syndrome of the trephined is yet another cause of orthostatic headaches without CSF leak. [source] The case against preoperative biliary drainage with pancreatic resectionHPB, Issue 6 2006Rurik C. Johnson The majority of patients with periampullary malignancies currently undergo biliary drainage before pancreaticoduodenectomy. Placement of an endoprosthesis reliably ameliorates jaundice and pruritus. However, preoperative biliary drainage leads to bile colonization and increases the risk of postoperative wound infection after pancreatic resection. Preoperative biliary drainage does not appear to lower postoperative morbidity or mortality following pancreatic resection and does not lower but probably increases costs associated with pancreatic resection. Preoperative biliary drainage is frequently used with little clinical benefit and its utilization should be limited to specific clinical indications, i.e. patients receiving neoadjuvant therapy, patients waiting several weeks or more for surgical evaluation and resection, patients with cholangitis. [source] Long-term (18-year) changes in sulphate concentrations in two Ontario headwater lakes and their inflows in response to decreasing deposition and climate variationsHYDROLOGICAL PROCESSES, Issue 14 2004M. C. Eimers Abstract Sulphate concentrations in two headwater lakes and their major inflows were evaluated over an 18 year period (1980,81 to 1997,98) during which time sulphate bulk deposition declined by approximately 40%. The two lake catchments represent either end of the spectrum of acid sensitivity in the Muskoka,Haliburton region of Ontario. Between 1980 and 1998, sulphate concentrations in Harp and Plastic Lakes decreased, but the decrease was much less than expected (28% and 21% respectively) given the magnitude of change in deposition. Sulphate export in streams draining into the lakes greatly exceeded sulphate input to catchments in most years, which quantitatively explains the response of lake-sulphate concentration. Furthermore, temporal patterns in mean annual sulphate concentrations in streams were similar, and appeared to be related to climate factors. Specifically, catchment export of sulphate was greater and stream-sulphate concentrations were higher in years that had warm, dry summers, i.e. when streamflow in many catchments ceased for up to several weeks. Increased sulphate export from catchments resulted in higher sulphate concentrations in lakes, but the response of lake sulphate was not as immediate or dramatic as the response of stream sulphate to changes in catchment dryness. Factors that affect sulphate retention or export in catchments exert a strong influence on sulphate concentrations in lakes and streams and need to be considered when evaluating the response of surface water chemistry to changes in sulphate deposition. Copyright © 2004 John Wiley & Sons, Ltd. [source] Within- and between-year variation in the juvenile survival of Common Guillemots Uria aalgeIBIS, Issue 3 2007MICHAEL P. HARRIS We studied juvenile survival of 20 cohorts of Common Guillemot Uria aalge chicks colour-ringed on the Isle of May, Scotland, using both live observations at the colony and dead recoveries, allowing estimation of fidelity to the colony as well as survival. In this seabird, chicks leave the colony when only partly grown and are cared for by the male parent for several weeks afterwards. First-year survival varied strongly between cohorts, with a mean of 56% (range 30,91%). We did not identify any covariates which could explain this variation, whether relating to climate, population size or prey density. Survival was low during two regime shift episodes in the North Sea (1987,90 and 2000 onwards). Early hatched chicks were substantially more likely to survive than those hatching later in most years, whereas body condition at ringing had no detectable effect. Ringing recoveries indicated that mortality was highest in mid-winter, i.e. well after the cessation of paternal care. These results do not support the hypothesis that variation in prey quantity or energy content before fledging is a primary driver of variation in juvenile survival. Rather, it seems that chicks of high-quality parents are more likely to survive, as high-quality females tend to lay earlier in the season, and high-quality males presumably are better able to prepare their chicks to survive their first winter at sea. Very few (4%) Guillemots emigrated permanently before age 3 years, but from age 5 onwards 25,30% of birds annually left the colony or otherwise became unobservable. [source] Growth of the tufted-tailed ratINTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 4 2007Vololomboahangy R. RANDRIANJAFY Abstract Eliurus myoxinus (Rodentia: Nesomyidae, Nesomyinae) is one of the four species of endemic Malagasy rodents known to exist in the Ankarafantsika National Park, northwestern Madagascar. In order to study growth parameters and to determine at which age E. myoxinus commences breeding, we used two different techniques: captive breeding and a capture-mark-release field program in the species' natural habitat. The data collected on the breeding of E. myoxinus in captivity demonstrated that females can give birth to a litter of up to four pups, with up to four litters per calendar year. Reproduction of E. myoxinus was more likely to be continuous in captivity than under natural habitat conditions. If parturition failed, then post-partum mating occurred. Pups had a rapid linear growth phase from birth until 1 month of age. Between 1.5 and 2 months of age, the growth rate continued to increase, but then decreased at around the time of weaning, which occurred by 3.5 months of age. The successive maximum method of age determination showed that individuals at the "young" stage had an average body length of 90 mm and a weight of 30 g and were between 1.5 and 2 months old. The greatest variation in measurements of juveniles occurred at the age of 3.5 months. At this stage, sub-adults resembled adults but their external genitalia were not well developed. Individuals were classified as adults if they had reached a body length of 110 mm and a body weight of 40 g. This occurred at more than 4.5 months of age when the animals were generally reproductively active. The Vo n Bertalanffy method indicated that individuals reach the adult stage by 6 to 7 months. Males grew more rapidly than females, reaching adulthood by 5.5 months of age, whereas females only reached adulthood several weeks later. This species is polygamous. The sex ratio of pups at birth favored females by approximately 3:1. The higher proportion of female pups at birth may represent a survival strategy of this species, possibly associated with ecological conditions. [source] Relationship between snow cover variability and Arctic oscillation index on a hierarchy of time scalesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2003A. S. Bamzai Abstract Based on satellite-derived global snow cover data on weekly time scales, the climatology and interannual variability of snow onset day-of-year, snowmelt day-of-year and number of snow-free days in a year are presented. Trends for snow onset day-of-year, snowmelt day-of-year and number of snow-free days in a year indicate that there has been an increase in number of snow-free days in recent decades. The relationship between snow cover and the Arctic oscillation (AO) index is examined on a hierarchy of time scales using lagged correlation and composite analysis. On weekly time scales, composite snow extent anomalies are maximum when AO leads snow cover by 1 week. These composite differences are maintained several weeks thereafter, particularly in the negative phase of the AO. Maps of composite snow cover anomalies when AO leads snow cover by 1 week delineate the spatial structure of these snow anomalies. On monthly time scales, lead,lag correlation between monthly snow cover and AO index indicates that the AO index during January, February and March is significantly correlated with snow cover in concurrent and subsequent spring months, particularly over Eurasia. Finally, on seasonal time scales, it is shown that winter season AO and winter/spring season snow cover are significantly correlated. Copyright © 2003 Royal Meteorological Society. [source] A rapid method to clinically assess the effect of an anti-acne formulationINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2010N. Muizzuddin J. Cosmet. Sci., 60, 25,29 (January/February 2009) Synopsis Historically, clinical evaluation of acne treatment has been based on direct visual assessment and the counting of lesions over a period of several weeks of treatment. However, with advancing technology there has been ever-increasing speed in the effectiveness of these treatments. To successfully assess these faster treatments, acne pathology needs to be evaluated in a shorter time frame. The object of these studies was to develop techniques to evaluate individual acne lesions in a shorter time frame and to assess speedier treatment technologies. Ten healthy volunteers with acne lesions on their upper backs were recruited for the study. Two inflamed acne lesions were selected for each treatment, along with lesions to be left untreated, on each volunteer. Each lesion was marked, photographed, and visually graded. A skin surface microscope (Scopeman) was used to visualize size and to grade the lesions by two experts every day for five days. The sites were treated once a day for the course of the study. There was a remarkable reduction in the size and erythema of acne lesions after treatment with the acne formulation as compared to the untreated and vehicle-treated lesions. Individual lesions, both treated and untreated, appeared resolved in 14 days. This resolution can be noticeably accelerated by topical treatments. We have developed a simple and faster clinical method to evaluate the effects of topical anti-acne technology. [source] | |||||||||||||||||||||||||||||||||||||||||||