Lower Sensitivity (lower + sensitivity)

Distribution by Scientific Domains

Selected Abstracts

Congenital Short QT Syndrome and Implantable Cardioverter Defibrillator Treatment:

Inherent Risk for Inappropriate Shock Delivery
Introduction: A congenital short QT interval constitutes a new primary electrical abnormality associated with syncope and/or sudden cardiac death. We report on the initial use of implantable cardioverter defibrillator (ICD) therapy in patients with inherited short QT interval and discuss sensing abnormalities and detection issues. Methods and Results: In five consecutive patients from two unrelated European families who had structurally normal hearts, excessively shortened QT intervals, and a strong positive family history of sudden cardiac death, ICDs were placed for primary and secondary prevention. Mean QT intervals were 252 ± 13 ms (QTc 287 ± 13 ms). Despite normal sensing behavior during intraoperative and postoperative device testing, 3 of 5 patients experienced inappropriate shock therapies for T wave oversensing 30 ± 26 days after implantation. Programming lower sensitivities and decay delays prevented further inappropriate discharges. Conclusion: The congenital short QT syndrome constitutes a new clinical entity with an increased risk for sudden cardiac death. Currently, ICD treatment is the only therapeutic option. In patients with short QT interval and implanted ICD, increased risk for inappropriate therapy is inherent due to the detection of short-coupled and prominent T waves. Careful testing of ICD function and adaptation of sensing levels and decay delays without sacrificing correct arrhythmia detection are essential. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1273-1277, December 2003) [source]

Investigating the role of ABC transporters in multifungicide insensitivity in Phytophthora infestans

SUMMARY Isolates of the oomycete Phytophthora infestans exhibit a wide range of intrinsic sensitivities to fungicides, which potentially influences the application rates of chemicals needed to control potato late blight. To help understand what determines such levels of sensitivity, a genetic approach was employed which followed the segregation of sensitivities to structurally diverse fungicides such as metalaxyl and trifloxystrobin. Progeny exhibited broad distributions of sensitivity phenotypes, consistent with the behaviour of a quantitative trait. Measurements of the inhibition of strains by seven fungicides revealed that basal sensitivities to metalaxyl and trifloxystrobin, and to cymoxanil and dimethomorph, correlated at the 95% confidence level. These compounds have distinct modes of action, suggesting the involvement of a multifungicide efflux phenomenon mediated by ABC transporters. To determine whether such proteins contribute to variation in sensitivity, 41 full transporters and 13 half transporters were identified from P. infestans and their mRNA levels compared in strains exhibiting higher or lower sensitivities to fungicides. No correlation was observed between the expression of any ABC transporter and fungicide sensitivity. Other genes, or variation in the activities of the transporters, may therefore explain the differences between strains. Five ABC transporters were induced by several fungicides in strains with both higher and lower sensitivities to fungicides, which probably reflects the existence of a network for protecting against natural and artificial toxins. [source]

Rice leaf growth and water potential are resilient to evaporative demand and soil water deficit once the effects of root system are neutralized

ABSTRACT Rice is known to be sensitive to soil water deficit and evaporative demand, with a greatest sensitivity of lowland-adapted genotypes. We have analysed the responses of plant water relations and of leaf elongation rate (LER) to soil water status and evaporative demand in seven rice genotypes belonging to different species, subspecies, either upland- or lowland-adapted. In the considered range of soil water potential (0 to ,0.6 MPa), stomatal conductance was controlled in such a way that the daytime leaf water potential was similar in well-watered, droughted or flooded conditions (isohydric behaviour). A low sensitivity of LER to evaporative demand was observed in the same three conditions, with small differences between genotypes and lower sensitivity than in maize. The sensitivity of LER to soil water deficit was similar to that of maize. A tendency towards lower sensitivities was observed in upland than lowland genotypes but with smaller differences than expected. We conclude that leaf water status and leaf elongation of rice are not particularly sensitive to water deficit. The main origin of drought sensitivity in rice may be its poor root system, whose effect was alleviated in the study presented here by growing plants in pots whose soil was entirely colonized by roots of all genotypes. [source]

HbA1c as a screening tool for detection of Type 2 diabetes: a systematic review

C. M. Bennett
Abstract Aim To assess the validity of glycated haemoglobin A1c (HbA1c) as a screening tool for early detection of Type 2 diabetes. Methods Systematic review of primary cross-sectional studies of the accuracy of HbA1c for the detection of Type 2 diabetes using the oral glucose tolerance test as the reference standard and fasting plasma glucose as a comparison. Results Nine studies met the inclusion criteria. At certain cut-off points, HbA1c has slightly lower sensitivity than fasting plasma glucose (FPG) in detecting diabetes, but slightly higher specificity. For HbA1c at a Diabetes Control and Complications Trial and UK Prospective Diabetes Study comparable cut-off point of , 6.1%, the sensitivity ranged from 78 to 81% and specificity 79 to 84%. For FPG at a cut-off point of , 6.1 mmol/l, the sensitivity ranged from 48 to 64% and specificity from 94 to 98%. Both HbA1c and FPG have low sensitivity for the detection of impaired glucose tolerance (around 50%). Conclusions HbA1c and FPG are equally effective screening tools for the detection of Type 2 diabetes. The HbA1c cut-off point of > 6.1% was the recommended optimum cut-off point for HbA1c in most reviewed studies; however, there is an argument for population-specific cut-off points as optimum cut-offs vary by ethnic group, age, gender and population prevalence of diabetes. Previous studies have demonstrated that HbA1c has less intra-individual variation and better predicts both micro- and macrovascular complications. Although the current cost of HbA1c is higher than FPG, the additional benefits in predicting costly preventable clinical complications may make this a cost-effective choice. [source]

Influence of water quality and age on nickel toxicity to fathead minnows (Pimephales promelas)

Tham Chung Hoang
Abstract This research characterized the effects of water quality and organism age on the toxicity of nickel (Ni)to fathead minnows (Pimephales promelas) to facilitate the accurate development of site-specific water-quality criteria. Nickel sulfate hexa-hydrate (NiSO4·6H2O) was used as the Ni source for performing acute toxicity tests (median lethal concentration after 96-h exposure [96-h LC50]) with <1-d-old and 28-d-old P. promelas under varying regimes of hardness, pH, alkalinity, and natural organic matter (NOM). The toxicity of Ni was inversely related to water hardness between hardness values of 20 and 150 mg/L (as CaCO3). Below 30 mg/L alkalinity, Ni toxicity was related to alkalinity. The effect of pH was confounded by hardness and the presence of NOM. In the absence of NOM, the toxicity of Ni increased as pH increased at high hardness and alkalinity. In general, 28-d-old fish were less sensitive than <1-d-old fish to Ni. This lower sensitivity ranged from 12-fold at low hardness and alkalinity (20 and 4 mg/L, respectively) to 5-fold at high hardness and alkalinity (100 and 400 mg/L, respectively). The presence of NOM (10 mg/L as dissolved organic carbon [DOC]) reduced Ni toxicity by up to 50%, but this effect appeared to be saturated above DOC at 5 mg/L. Incubating Ni with the NOM solution from 1 to 17 days had no effect on Ni toxicity. When using multivariate analysis, the 96-h LC50 for Ni was a function offish age, alkalinity, hardness, and NOM (96-h LC50 = ,0.642 + 0.270(fish age) + 0.005(alkalinity) + 0.018(hardness) + 0.138(DOC)). When using this model, we found a strong relationship between measured and predicted 96-h LC50 values (r2 = 0.94) throughout the treatment water qualities. The biotic ligand model (BLM) did not accurately predict Ni toxicity at high or low levels of alkalinity. Results of our research suggest that the BLM could be improved by considering NiCO3 to be bioavailable. [source]

Validation of a brief screening instrument for the ascertainment of epilepsy

EPILEPSIA, Issue 2 2010
Ruth Ottman
Summary Purpose:, To validate a brief screening instrument for identifying people with epilepsy in epidemiologic or genetic studies. Methods:, We designed a nine-question screening instrument for epilepsy and administered it by telephone to individuals with medical record,documented epilepsy (lifetime history of ,2 unprovoked seizures, n = 168) or isolated unprovoked seizure (n = 54), and individuals who were seizure-free on medical record review (n = 120), from a population-based study using Rochester Epidemiology Project resources. Interviewers were blinded to record-review findings. Results:, Sensitivity (the proportion of individuals who screened positive among affected individuals) was 96% for epilepsy and 87% for isolated unprovoked seizure. The false positive rate (FPR, the proportion who screened positive among seizure-free individuals) was 7%. The estimated positive predictive value (PPV) for epilepsy was 23%, assuming a lifetime prevalence of 2% in the population. Use of only a single question asking whether the subject had ever had epilepsy or a seizure disorder resulted in sensitivity 76%, FPR 0.8%, and estimated PPV 66%. Subjects with epilepsy were more likely to screen positive with this question if they were diagnosed after 1964 or continued to have seizures for at least 5 years after diagnosis. Discussion:, Given its high sensitivity, our instrument may be useful for the first stage of screening for epilepsy; however, the PPV of 23% suggests that only about one in four screen-positive individuals will be truly affected. Screening with a single question asking about epilepsy yields a higher PPV but lower sensitivity, and screen-positive subjects may be biased toward more severe epilepsy. [source]

Effect of Decrease of Hydride-Induced Embrittlement in Nanocrystalline Titanium,

M.A. Murzinova
Abstract The room-temperature impact toughness, strength and ductility of nanocrystalline (NC) and microcrystalline (MC) titanium with hydrogen content ranging from 0.1 to 16,at.-% (0.002 to 0.450,wt.-%) are studied. NC titanium has higher strength and lower sensitivity to hydride-induced brittle fracture than the MC material. In contrast to MC titanium, the elongation and impact toughness in the NC material does not decrease dramatically with increasing hydrogen content. Moreover, the fracture toughness in hydrogenated NC condition is found to be higher than that in MC titanium. This unusual result may be associated with the precipitation of equiaxial nanoscale hydrides in the interior of ,-grains in the NC material, while platelet hydrides are formed in MC titanium. One can expect that the risk of hydride-induced embrittlement is lower in NC than in MC titanium, making the NC material attractive for potential application under conditions that may cause hydrogen saturation above the permissible level for MC titanium. [source]

Play and emotional availability in young children with Down syndrome

Paola Venuti
This study investigates mother,child interaction and its associations with play in children with Down syndrome (DS). There is consensus that mother,child interaction during play represents an important determinant of typical children's play development. Concerning children with DS, few studies have investigated mother,child interaction in terms of the overall emotional quality of dyadic interaction and its effect on child play. A sample of 28 children with DS (M age = 3 years) took part in this study. In particular, we studied whether the presence of the mother in an interactional context affects the exploratory and symbolic play of children with DS and the interrelation between children's level of play and dyadic emotional availability. Children showed significantly more exploratory play during collaborative play with mothers than during solitary play. However, the maternal effect on child symbolic play was higher in children of highly sensitive mothers relative to children whose mothers showed lower sensitivity, the former displaying more symbolic play than the latter in collaborative play. Results offer some evidence that dyadic emotional availability and child play level are associated in children with DS, consistent with the hypothesis that dyadic interactions based on a healthy level of emotional involvement may lead to enhanced cognitive functioning. [source]

Protein kinase B modulates the sensitivity of human neuroblastoma cells to insulin-like growth factor receptor inhibition

Ana S. Guerreiro
Abstract The potential of the novel insulin-like growth factor receptor (IGF-IR) inhibitor NVP-AEW541 as an antiproliferative agent in human neuroblastoma was investigated. Proliferation of a panel of neuroblastoma cell lines was inhibited by NVP-AEW541 with IC50 values ranging from 0.15 to 5 ,M. Experiments using an IGF-IR neutralizing antibody confirmed that the IGF-IR was essential to support growth of neuroblastoma cell lines. The expression levels of the IGF-IR in individual neuroblastoma cell lines did not correlate with the sensitivities to NVP-AEW541, while coexpression of the IGF-IR and the insulin receptor (IR) correlated with lower sensitivity to the inhibitor in some cell lines. Intriguingly, high levels of activation of Akt/protein kinase B (PKB) and phosphorylation of the ribosomal S6 protein were observed in neuroblastoma cell lines with decreased sensitivities to NVP-AEW541. Inhibition of Akt/PKB activity restored the sensitivity of neuroblastoma cells to the IGF-IR inhibitor. Transfection of neuroblastoma cells with activated Akt or ribosomal protein S6 kinase (S6K) decreased the sensitivity of the cells to NVP-AEW541. IGF-I-stimulated proliferation of neuroblastoma cell lines was completely blocked by NVP-AEW541, or by a combination of an inhibitor of phosphoinositide 3-kinase and rapamycin. In addition to its antiproliferative effects, NVP-AEW541 sensitized neuroblastoma cells to cisplatin-induced apoptosis. Together, our data demonstrate that NVP-AEW541 in combination with Akt/PKB inhibitors or chemotherapeutic agents may represent a novel approach to target human neuroblastoma cell proliferation. © 2006 Wiley-Liss, Inc. [source]

The role of genotype-specific human papillomavirus detection in diagnosing residual cervical intraepithelial neoplasia

Ruud LM Bekkers
Abstract We assessed prospectively whether residual cervical intraepithelial neoplasia (CIN) after treatment for high-grade CIN can be predicted by genotype-specific high-risk HPV (HR-HPV) detection in follow-up cervical scrapes. A broad spectrum, highly sensitive SPF10 -LiPA-PCR HPV detection technique was used on cervical scrapes before large loop excision of the transformation zone (LLETZ), on the LLETZ biopsy and on follow-up scrapes of 90 patients treated for high-grade CIN. HR-HPV was detected in the biopsies of 93% (n = 84) of the patients and in the follow-up scrapes of 48% (n = 43) of the patients. In 12 patients, genotype-specific HR-HPV persistence was detected in both follow-up scrapes. In 10 patients, residual CIN was detected. In 5 of these patients (including all patients with residual CIN 3), the follow-up scrapes showed genotype-specific HR-HPV persistence. In 2 patients, a different HR-HPV was detected, and 3 patients had HR-HPV-negative follow-up scrapes. Conventional cytologic follow-up was abnormal in 13 patients including all 10 patients with residual CIN. The negative predictive value (NPV) of HR-HPV detection on follow-up scrapes was high (94%). Repeat detection of genotype-specific HR-HPV showed a lower sensitivity and NPV than repeat detection of any HR-HPV, but its specificity was higher. Repeat conventional cytologic follow-up showed the highest sensitivity and NPV. In conclusion, the presence of HR-HPV in cervical scrapes after LLETZ for high-grade CIN is a risk factor for the presence of residual CIN. HR-HPV genotype-specific persistence is specifically present in patients with residual CIN 3. However, HR-HPV detection cannot predict or exclude the presence of residual CIN in the individual patient and additional procedures remain necessary. © 2002 Wiley-Liss, Inc. [source]

Does Risk Management Add Value?

A Survey of the Evidence
The fact that 92% of the world's 500 largest companies recently reported using derivatives suggests that corporate managers believe financial risk management can increase shareholder value. Surveys of finance academics indicate that they too believe that corporate risk management is, on the whole, a valueadding activity. This article provides an overview of almost 30 years of broadbased, stock-market-oriented academic studies that address one or more of the following questions: ,Are interest rate, exchange rate, and commodity price risks reflected in stock price movements? ,Is volatility in corporate earnings and cash flows related in a systematic way to corporate market values? ,Is the corporate use of derivatives associated with reduced risk and higher market values? The answer to the first question, at least in the case of financial institutions and interest rate risk, is a definite yes; all studies with this focus find that the stock returns of financial firms are clearly sensitive to interest rate changes. The stock returns of industrial companies exhibit no pronounced interest rate exposure (at least as a group), but industrial firms with significant cross-border revenues and costs show considerable sensitivity to exchange rates (although such sensitivity actually appears to be reduced by the size and geographical diversity of the largest multinationals). What's more, the corporate use of derivatives to hedge interest rate and currency exposures appears to be associated with lower sensitivity of stock returns to interest rate and FX changes. But does the resulting reduction in price sensitivity affect value,and, if so, how? Consistent with a widely cited theory that risk management increases value by limiting the corporate "underinvestment problem," a number of studies show a correlation between lower cash flow volatility and higher corporate investment and market values. The article also cites a small but growing group of studies that show a strong positive association between derivatives use and stock price performance (typically measured using price-to-book ratios). But perhaps the nearest the research comes to establishing causality are two studies,one of companies that hedge FX exposures and another of airlines' hedging of fuel costs,that show that, in industries where hedging with derivatives is common, companies that hedge outperform companies that don't. [source]

Detection of Explosives in Hair Using Ion Mobility Spectrometry

Jimmie C. Oxley Ph.D.
Abstract:, Conventional explosives 2,4,6-trinitrotoluene (TNT), nitroglycerin (NG), and ethylene glycol dinitrate (EGDN) sorbed to hair can be directly detected by an ion mobility spectrometer (IMS) in E-mode (for explosives). Terrorist explosive, triacetone triperoxide (TATP), difficult to detect by IMS in E-mode, was detected in N-mode (for narcotics). Three modes of sample introduction to IMS vapor desorption unit were used: (i) placement of hair directly into the unit, (ii) swabbing of hair and placement of swabs (i.e., paper GE-IMS sample traps) into the unit, and (iii) acetonitrile extracts of hair positioned on sample traps and placed into the unit. TNT, NG, and EGDN were detected in E-mode by all three sample introduction methods. TATP could only be detected by the acetonitrile extraction method after exposure of the hair to vapor for 16 days because of lower sensitivity. With standard solutions, TATP detection in E-mode required about 10 times as much sample as EGDN (3.9 ,g compared with 0.3 ,g). IMS in N-mode detected TATP from hair by all three modes of sample introduction. [source]

Acute retinal necrosis six years after herpes simplex encephalitis: An elusive immune deficit suggested by insufficient test sensitivity

W. Preiser
Abstract A patient presented with acute retinal necrosis of the left eye. Demonstration of herpes simplex virus (HSV) DNA in the aqueous humour confirmed the diagnosis. Negative results of HSV type-specific antibody tests based on gG antigens suggested a primary HSV infection. However, the patient had a past history of laboratory-confirmed herpes simplex encephalitis 6 years ago. Using antibody tests based on whole viral lysate antigens, he was seropositive from the onset, and immunoblot testing confirmed a lack of anti-gG reactivity. To be able to assess whether this might be related to the apparent inability of his immune system to suppress clinically symptomatic HSV infection, serial samples were tested by an HSV neutralisation test and a whole-blood flow cytometric assay to determine the frequency of HSV-specific CD4 lymphocytes. However, this did not yield evidence of obvious immunodeficiency; the patient reacted similarly to known positive controls by both assays. Although type-specific HSV serological tests based on gG are generally more specific than those based on whole viral lysate antigens, they have a somewhat lower sensitivity, as a certain percentage of HSV-infected individuals do not develop antibodies against gG, and others may suffer a secondary loss of anti-gG reactivity. Thus there is a risk of missing individual infected patients. Unless this potential problem is recognised, serious consequences might possibly result. We therefore urge virologists and clinicians to exercise great care if highly specific antibody assays based on recombinant proteins are employed. J. Med. Virol. 73:250,255, 2004. © 2004 Wiley-Liss, Inc. [source]

Interactions of Stress and CRF in Ethanol-Withdrawal Induced Anxiety in Adolescent and Adult Rats

ALCOHOLISM, Issue 9 2010
Tiffany A. Wills
Background:, Repeated stress or administration of corticotropin-releasing factor (CRF) prior to ethanol exposure sensitizes anxiety-like behavior in adult rats. Current experiments determined whether adolescent rats were more sensitive to these challenges in sensitizing ethanol withdrawal-induced anxiety and altering CRF levels in brain during withdrawal. Methods:, Male adult and adolescent Sprague,Dawley rats were restraint stressed (1 hour) twice 1 week apart prior to a single 5-day cycle of ethanol diet (ED; stress/withdrawal paradigm). Other rats received control diet (CD) and three 1-hour restraint stress sessions. Rats were then tested 5, 24, or 48 hours after the final withdrawal for anxiety-like behavior in the social interaction (SI) test. In other experiments, adolescent rats were given two microinjections of CRF icv 1 week apart followed by 5 days of either CD or ED and tested in social interaction 5 hours into withdrawal. Finally, CRF immunoreactivity was measured in the central nucleus of the amygdala (CeA) and paraventricular nucleus (PVN) after rats experienced control diet, repeated ethanol withdrawals, or stress/withdrawal. Results:, Rats of both ages had reduced SI following the stress/withdrawal paradigm, and this effect recovered within 24 hours. Higher CRF doses were required to reduce SI in adolescents than previously reported in adults. CRF immunohistochemical levels were higher in the PVN and CeA of CD-exposed adolescents. In adolescent rats, repeated ethanol withdrawals decreased CRF in the CeA but was not associated with decreased CRF cell number. There was no change in CRF from adult treatments. Conclusions:, In the production of anxiety-like behavior, adolescent rats have equal sensitivity with stress and lower sensitivity with CRF compared to adults. Further, adolescents had higher basal levels of CRF within the PVN and CeA and reduced CRF levels following repeated ethanol withdrawals. This reduced CRF within the CeA could indicate increased release of CRF, and future work will determine how this change relates to behavior. [source]

Ethanol Acutely Modulates mGluR1-Dependent Long-Term Depression in Cerebellum

ALCOHOLISM, Issue 7 2010
Li-Da Su
Background:, Acute and chronic ethanol exposure produces profound impairments in motor functioning. Individuals with lower sensitivity to the acute motor impairing effects of ethanol have an increased risk of developing alcohol dependence and abuse, and infants with subtle delays in motor coordination development may have an increased risk for subsequently developing alcoholism. Thus, understanding the mechanism by which ethanol disrupts motor functioning is very important. Methods:, Parasagittal slices of the cerebellar vermis (250 ,M thick) were prepared from P17 to 20 Sprague,Dawley rats. Whole-cell recordings of Purkinje cells were obtained with an Axopatch 200B amplifier. Parallel fiber-Purkinje cell synaptic currents were sampled at 1 kHz and digitized at 10 kHz, and synaptic long-term depression (LTD) was observed in either external or internal application of ethanol for comparison. Results:, We determined whether ethanol acutely affects parallel fiber LTD using whole-cell patch-clamp recordings from Purkinje cells. Application of ethanol both externally (50 mM) and internally (17 and 10 mM) significantly suppressed mGluR-mediate slow currents. Short-term external ethanol exposure (50 but not 17 mM) during tetanus blocked mGluR-dependent parallel fiber LTD. Furthermore, internal 17 and 10 mM ethanol completely inhibited this LTD. Conclusions:, The results of the current study demonstrate that ethanol acutely suppresses parallel fiber LTD and may influence the mGluR-mediated slow current intracellularly. This study, plus previous evidence by Carta and colleagues (2006) and Belmeguenai and colleagues (2008), suggests significant actions of ethanol on mGluR-mediated currents and its dependent plasticity in brain. [source]

Molecular and serological characterization of hepatitis B virus in deferred Ghanaian blood donors with and without elevated alanine aminotransferase

D. Candotti
Summary., Candidate blood donors in Ghana are frequent carriers of hepatitis B virus (HBV). A comparative study of 117 donor samples including 46 with alanine aminotransferase (ALT) , 60 IU/L and 71 with ,40 IU/L level was undertaken. S and the basic core promoter-precore regions (BCP/PC) sequencing was used to identify genotypes and variants relevant to HBV natural history, respectively. Age, viral load, HBe status were correlated with molecular data. HBV genotype E (87%) was dominant with little genotypes A (10%) and D (3%). Comparing individuals with or without liver disease, an association between liver disease and older age (P = 0.004) and higher viral load (P = 0.002) whether as a whole population or only genotype E was found. Compared with a commercial assay, BCP/PC sequencing had lower sensitivity to detect mixtures of wild-type and variant viruses but detected BCP deletions. BCP 1762/1764 variants were positively correlated with older age (P < 0.0001) and elevated ALT levels (P = 0.01). PC 1896 stop codon was marginally correlated with viral load (P = 0.09). HBV genotype E infection natural history appears different from genotypes B and C prevalent in Asia. Donors with liver disease being older, with higher viral load and higher BCP variant proportion may be at higher risk of cirrhosis and hepatocellular carcinoma [source]

Interaction of UV Radiation and Inorganic Carbon Supply in the Inhibition of Photosynthesis: Spectral and Temporal Responses of Two Marine Picoplankters,

Cristina Sobrino
ABSTRACT The effect of ultraviolet radiation (UVR) on inhibition of photosynthesis was studied in two species of marine picoplankton with different carbon concentration mechanisms: Nannochloropsis gaditana Lubián possesses a bicarbonate uptake system and Nannochloris atomus Butcher a CO2 active transport system. Biological weighting functions (BWFs) for inhibition of photosynthesis by UVR and photosynthesis vs irradiance (PI) curves for photosynthetically active radiation (PAR) were estimated for both species grown with an enriched CO2 supply (high dissolved inorganic carbon [DIC]: 1% CO2 in air) and in atmospheric CO2 levels (low DIC: 0.03% CO2). The response to UVR and PAR exposures was different in each species depending on the DIC treatment. Under PAR exposure, rates of maximum photosynthesis were similar between treatments in N. gaditana. However, the cultures growing in high DIC had lower sensitivity to UVR than the low DIC cultures. In contrast, N. atomus had higher rates of photosynthesis under PAR exposure with high DIC, but the BWFs were not significantly different between treatments. The results suggest that one or more processes in N. gaditana associated with HCO3, transport are target(s) for UV photodamage because there was relatively less UV inhibition of the high DIC-grown cultures in which inorganic carbon fixation is supplied by passive CO2 diffusion. Time courses of photochemical efficiency in PAR, during UV exposure and during subsequent recovery in PAR, were determined using a pulse amplitude modulated fluorometer. The results were consistent with the BWFs. In all time courses, a steady state was obtained after an initial decrease, consistent with a dynamic balance between damage and repair as found for other phytoplankton. However, the relationship of response to exposure showed a steep decline in activity that is consistent with a constant rate of repair. A novel feature of a model developed from a constant repair rate is an explicit threshold for photosynthetic response to UV. [source]

Rice leaf growth and water potential are resilient to evaporative demand and soil water deficit once the effects of root system are neutralized

ABSTRACT Rice is known to be sensitive to soil water deficit and evaporative demand, with a greatest sensitivity of lowland-adapted genotypes. We have analysed the responses of plant water relations and of leaf elongation rate (LER) to soil water status and evaporative demand in seven rice genotypes belonging to different species, subspecies, either upland- or lowland-adapted. In the considered range of soil water potential (0 to ,0.6 MPa), stomatal conductance was controlled in such a way that the daytime leaf water potential was similar in well-watered, droughted or flooded conditions (isohydric behaviour). A low sensitivity of LER to evaporative demand was observed in the same three conditions, with small differences between genotypes and lower sensitivity than in maize. The sensitivity of LER to soil water deficit was similar to that of maize. A tendency towards lower sensitivities was observed in upland than lowland genotypes but with smaller differences than expected. We conclude that leaf water status and leaf elongation of rice are not particularly sensitive to water deficit. The main origin of drought sensitivity in rice may be its poor root system, whose effect was alleviated in the study presented here by growing plants in pots whose soil was entirely colonized by roots of all genotypes. [source]

Small bowel tumours: a 10 year experience in four sydney teaching hospitals

David S. Rangiah
Background: Small bowel tumours are uncommon and can have a long delay prior to diagnosis. The present study aims to compare the use of computed tomography (CT) and contrast small bowel series (SBS) in their diagnosis and to outline the clinical features of small bowel tumours. Methods: A retrospective, case note study was conducted between 1990 and 2000 in four Sydney teaching hospitals. The data collected included clinical features, investigations and tumour characteristics. Results: One hundred and sixty-six people with small bowel tumours were identified (91 malignant; 75 benign). Malignant tumours consisted of adenocarcinomas (31%), carcinoid tumours (12%), lymphomas (7%) and leiomyosarcomas (5%). Benign tumours consisted of adenomas (22%), hamartomas (13%), leiomyomas (4%), inflammatory polyps (4%) and hyperplastic polyps (2%) and a benign schwannoma (1%). Adenocarcinomas were mainly located in the duodenum (P < 0.001) and carcinoid tumours in the ileum (P < 0.001). Malignant tumours were associated with a higher proportion of symptoms (P < 0.01), signs (P < 0.001) and episodes of small bowel obstruction (P < 0.01). Abdominal CT scans demonstrated a greater sensitivity (87.7%) than SBS (72.9%) with a slightly improved sensitivity when both investigations were used (89.3%). Abdominal ultrasound had a lower sensitivity than both of the above investigations of 65%. Gastroduodenoscopy had a sensitivity of 90% for diagnosing duodenal tumours. Operative procedures were performed on 92 patients with a preoperative diagnosis made in 77%. Metastatic spread of malignant tumours was evident in 46%. The sites of spread were to lymph nodes (23%), liver (21%) and distant locations (2%) at diagnosis. Conclusions: Malignant small bowel tumours are more likely to produce symptoms and signs than benign tumours, particularly caused by small bowel obstruction. Abdominal CT is the best radiological investigation for small bowel tumours and has a slight complimentary effect with SBS in improving the chances of detection. Gastroduodenoscopy remains the best investigation of duodenal tumours. [source]

Temporal and spatial patterns of ecosystem functioning in protected arid areas in southeastern Spain

José M. Paruelo
Abstract We characterized the spatial variability and temporal dynamics of the photosynthetic active radiation absorbed (APAR) by the canopy, a descriptor of ecosystem functioning, in Cabo de Gata , Níjar Natural Park (CGNNP) (Spain). Ecosystem functioning was characterized for five landscape classes using the Normalized Difference Vegetation Index (NDVI) derived from NOAA/AVHRR LAC (1 km × 1 km) images. We also used a 19-year time series of NDVI PAL data (8 km × 8 km) to analyse the relationship APAR-precipitation inside and outside the park. The vegetation of CGNNP absorbed less than 20% of the incoming radiation. Plains intercepted 37% and hills 14% less photosynthetic active radiation than mountains, the most productive landscape of the park. CGNNP showed a well-defined growing season with a unique peak of APAR. Plains and piedmont, covered by annual vegetation displayed an earlier development of the leaf area index than the shrublands and grasslands typical of the other landscapes. APAR had a significant relationship with the sum of the precipitation of the current and two previous growing seasons, except for the plains. We found that the APAR of the areas more modified by humans (outside the park) showed a lower sensitivity to changes in precipitation than those under protection. The differences were higher if the accumulated precipitation of the previous three growing seasons was considered. The description of such differences in the response of absorbed PAR to water availability are proposed as the base of a monitoring system for semi-arid and arid areas. [source]

Ethnicity affects the diagnostic validity of alpha-fetoprotein in hepatocellular carcinoma

Amal GAD
Abstract Introduction: Hepatocellular carcinoma (HCC) is the fourth most common cancer worldwide with a high morbidity and mortality. Alpha-fetoprotein (AFP) is considered the main tumor marker for HCC diagnosis, but the variation in its diagnostic validity among studies justifies further investigation of the underlying contributing factors. Ethnic difference could be one of the factors that has not been well studied. We aimed at investigating the ethnic difference in AFP validity between Egyptian (representing Arabic North African) and Japanese (representing Asian) for HCC diagnosis. Methods: Four cohorts with chronic liver diseases (CLD) were studied: 171 Egyptian (65 HCC/106 non-HCC), and 173 Japanese (45 HCC/128 non-HCC). Laboratory tests including serum AFP, protein-induced vitamin K deficiency or absence (PIVKA-II), alanine aminotransferase (ALT), total bilirubin, platelet count, HBsAg, anti-HCV, and HCV core antigen were conducted using standard commercially available assays. Results: A significantly higher sensitivity of AFP in Egyptian in comparison with Japanese for HCC diagnosis (99 vs 67%, P < 0.001) was observed using an AFP cut-off point of 10 ng/mL, with a comparable specificity, (75,vs, 82%), While, a, sensitivity, of, 98, versus, 56%,,P < 0.001, and, a, specificity, of, 83, versus, 89% was found for AFP cut-off point of 20 ng/mL, respectively. The area under the receiver operating characteristic curve (ROC) was found to be 0.98 (95%CI = 0.969,0.997) for Egyptian and 0.77 (95%CI = 0.686,0.864) for Japanese. The highest sensitivity for the former group occurred at AFP = 20.5 ng/mL and at AFP = 10.2 ng/mL for the latter. Univariate analysis showed no effect for age, sex, underlying liver disease, cirrhosis, Child's class or tumor characteristics (size, pathological grade) on AFP sensitivity, while race significantly contributed to the higher sensitivity among Egyptians in comparison with the Japanese. Using ROC analysis, the AFP cut-off point for HCC detection in each subgroup of patients with and without each of the risk factors of interest was determined and the subgroups were again subclassified according to AFP positivity (< or , the decided cut-off point for each group). Logistic regression analysis of those factors combined showed that Egyptian ethnicity with an AFP level >20.5 ng/mL (P = 0.007), older age (>50 years) with an AFP level >26 ng/mL (P = 0.010), and cirrhosis with an AFP level >10.5 ng/mL (P = 0.014) were the independent risk factors for HCC. Conclusion: There is an ethnic variation in AFP validity between Egyptian and Japanese patients with a significantly lower sensitivity in the latter. Alpha-fetoprotein should not be the only marker used for screening HCC among Asian Japanese and younger age groups (<50 years) with CLD. In addition, an AFP cut-off point of 20 ng/mL is recommended when screening patients of Asian origin for HCC. [source]

Electromagnetic fields alter the expression of estrogen receptor cofactors in breast cancer cells

Rainer Girgert
Abstract Breast cancer is the most common malignancy of women in Western societies. The increasing exposure to electromagnetic fields has been suspected to contribute to the rising incidence of breast cancer in industrialized countries. The majority of breast tumors is treated with the partial antiestrogen tamoxifen. Most tumors become resistant to tamoxifen in the course of treatment resulting in treatment failure. Electromagnetic fields reduce the efficacy of tamoxifen similar to tamoxifen resistance. In this study we investigated the mechanism by which electromagnetic fields influence the sensitivity to tamoxifen. In cells exposed to 1.2 µT of a 50 Hz electromagnetic field gene expression of cofactors of the estrogen receptors was compared to sham exposed cells. Using a gene array technology several cofactors were found to be differentially expressed. The expression of the coactivators, SRC-1 and AIB1, and of two corepressors, N-Cor and SMRT, was quantified by RT-PCR. Both coactivators were expressed more strongly in the exposed cells while the expression of two corepressors decreased. The RNA analysis was confirmed by Western blots. The contradirectional changes in gene expression of coactivators and corepressors by electromagnetic fields results in a lower sensitivity to tamoxifen. Electromagnetic fields may contribute to the induction of tamoxifen resistance in vivo. Bioelectromagnetics 29:169,176, 2008. © 2007 Wiley-Liss, Inc. [source]

The Six-item Screener to Detect Cognitive Impairment in Older Emergency Department Patients

Scott T. Wilber MD
Abstract Background:, Cognitive impairment due to delirium or dementia is common in older emergency department (ED) patients. To prevent errors, emergency physicians (EPs) should use brief, sensitive tests to evaluate older patient's mental status. Prior studies have shown that the Six-Item Screener (SIS) meets these criteria. Objectives:, The goal was to verify the performance of the SIS in a large, multicenter sample of older ED patients. Methods:, A prospective, cross-sectional study was conducted in three urban academic medical center EDs. English-speaking ED patients ,65 years old were enrolled. Patients who received medications that could affect cognition, were too ill, were unable to cooperate, were previously enrolled, or refused to participate were excluded. Patients were administered either the SIS or the Mini-Mental State Examination (MMSE), followed by the other test 30 minutes later. An MMSE of 23 or less was the criterion standard for cognitive impairment; the SIS cutoff was 4 or less for cognitive impairment. Standard operator characteristics of diagnostic tests were calculated with 95% confidence intervals (CIs), and a receiver operating characteristic curve was plotted. Results:, The authors enrolled 352 subjects; 111 were cognitively impaired by MMSE (32%, 95% CI = 27% to 37%). The SIS was 63% sensitive (95% CI = 53% to 72%) and 81% specific (95% CI = 75% to 85%). The area under the receiver operating characteristic curve was 0.77 (95% CI = 0.72 to 0.83). Conclusions:, The sensitivity of the SIS was lower than in prior studies. The reasons for this lower sensitivity are unclear. Further study is needed to clarify the ideal brief mental status test for ED use. [source]