Biosensors based on membrane-bound enzymes immobilized in a 5-(octyldithio)-2-nitrobenzoic acid layer on gold electrodes

Gold electrodes were modified through chemisorption of 5-(octyldithio)-2-nitrobenzoic acid (ODTNB). ODTNB includes a long chain in a short-length thio acid, providing a heterogeneous-like alkanethiol layer after adsorption on gold electrodes. Membrane-bound enzymes, in particular D-fructose dehydrogenase (FDH), D-gluconate dehydrogenase (GADH), and L-lactic dehydrogenase (cytochrome b2) (Cyb2), were immobilized onto ODTNB-modified gold electrodes simply by adsorption. The short-length thio acid may provide electrostatic interactions with enzyme surface charges, while the alkanethiolate enables hydrophobic interaction with the largely lipophilic, membrane-bound enzymes. The immobilization of FDH, GADH, and Cyb2 onto ODTNB-modified gold surfaces has been studied with the quartz crystal microbalance (QCM). Spectrophotometric and electrochemical assays indicate that the immobilized enzyme retains its enzymatic activity after immobilization onto the ODTNB-modified gold surface. The amount of immobilized (and active) enzyme was estimated from QCM to be of the order of 2.5 x 10(-12)-5.3 x 10(-12) mol x cm(-2). A fructose biosensor was developed, making use of a gold surface modified with ODTNB and fructose dehydrogenase, employing hydroxymethylferrocene as a mediator in solution. Calibration curves exhibited a linear relation between the biosensor response and the substrate concentration up to 0.7 mM. Statistical analysis gave an excellent linear correlation (r = 0.9993) and a sensitivity of 6.1 mM(-1) fructose. The biosensor shows a significant stable catalytic current for at least 25 days.     

Gastric versus duodenal feeding and gastric tonometric measurements

OBJECTIVE: To compare the influence of gastric and postpyloric enteral feeding on the gastric tonometric PCO2 gap (tonometric PCO2 - PaCO2). DESIGN: A prospective, clinical trial. SETTING: Two intensive care units in a university hospital. PATIENTS: Twenty patients undergoing mechanical ventilation and enteral feeding without catecholamines, sepsis, or sign of hypoxia. INTERVENTIONS: Patients were randomized to receive feeding through the tonometer (gastric group), or through a postpyloric tube (postpyloric group). MEASUREMENTS AND MAIN RESULTS: The patients received tube feeding at a rate of 50 mL/hr during 4 hrs. Baseline measurements included: mean arterial pressure, heart rate, tonometric parameters, arterial gases, and arterial lactate concentration. Except for lactate concentration, these measurements were repeated after 1 and 4 hrs of enteral feeding and 2 hrs after stopping enteral feeding. During the study, arterial pH and PaCO2 did not change. During enteral feeding, the PCO2 gap increased in the gastric group from a mean of 7+/-5 to 17+/-14 (SD) torr (0.9 0.7 to 2.3+/-1.9 kPa) (p< .O01) and did not change in the postpyloric group (5+/-5 to 3+/-1 torr [0.7+/-0.7 to 0.4+/-0.1 kPa]). Two hours after stopping enteral feeding, the PCO2 gap was still increased in the gastric group (15+/-9 vs. 7+/-5 torr [2.0+/-1.2 vs. 0.9+/-0.7 kPa]) (p < .01). CONCLUSION: The results indicate that gastric enteral feeding increased the PCO2 gap. However, postpyloric enteral feeding does not interact with gastric tonometric measurements and should be used when using gastric tonometry in enterally fed patients.     

Rapid progress of cirrhosis in hepatitis C: the role of age at the time of viral contamination

OBJECTIVE: The aim of this study was to assess predictive factors for the progression to liver cirrhosis in hepatitis C. METHODS: One hundred thirty six patients (79 men; 57 women; mean age 39 years) with transfusion or intravenous drug use-associated hepatitis C virus (HCV) infection were studied. Sex, cause of infection, duration of contamination, and genotype were studied as predictive factors of progression to liver cirrhosis. RESULTS: One hundred twenty three patients presented with chronic hepatitis without cirrhosis and 13 had cirrhosis. At the time of liver biopsy, rates of cirrhosis were: 0% before 40 years, 10% between 40 and 60 years, and 47% after 60 years. (p < 0.05). Rates of cirrhosis according to the age at the time of contamination were as follows: 3% before 30 years; 16% between 30 and 50 years; 46% after 50 years even though duration of the disease was comparable in the three groups. In multivariate analysis, two independent factors were associated with liver cirrhosis: age at contamination and duration of infection. CONCLUSION: Duration of infection and especially age at contamination seem better correlated with the probability of cirrhosis than the route of transmission or the genotype 1b. The results of this study suggest that progression to cirrhosis is slower in cases of contamination before 30 years of age than later on. Age at the time of contamination is an important predictive factor of progression to cirrhosis.     

School consultation research: Past trends and future directions.

Reviews and evaluates school consultation research conducted during the past decade. Attention is given to the breadth and quality of the present consultation knowledge base, the appropriateness of data analysis procedures, and the impact of consultation research findings on consultation training. Recommendations for future directions in school consultation research are offered from both methodological and substantive perspectives. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tuberculosis: epidemiological, bacteriological and therapeutic changes

The regular decline in the incidence of tuberculosis up to 1985 left us with the hope that the disease might one day be totally irradicated. But from 1985 on the number of cases has remained unchanged at about 8000 new cases per year in France. Resistant strains have also been identified, requiring new treatment strategies. Polyresistant strains may develop because of non-compliance to standard treatment or, particularly in immunosuppressed patients with AIDS, infection with atypical mycobacteria such as Mycobacterium avium. In developed countries, prophylactic measures for tuberculosis should be based on early diagnosis, rapid initiation of a proven treatment protocol not only to obtain cure but also to reduce contagion, and avoiding contract between high-risk patients. Chemoprophylaxy should be prescribed in case of doubt about contact as the tuberculin test is no longer discriminate due to widespread vaccination. For AIDS patients, the treatment protocol is the same as for normal subjects but should be prolonged. In case of M. avium infection, the most effective treatment combines pyrazinamide, clarithromycin and a third anti-tuberculosis drug.     

Histamine does not potentiate cyclic AMP-mediated amylase secretion in the guinea-pig pancreatic acinar cells

Some chemotherapeutic agents, as well as TNF and Fas, induce apoptotic cell death in tumor cells, but the cellular components involved in the process have not yet been identified. Interleukin 1 beta converting enzyme (ICE) is a mammalian homolog of CED-3, a protein required for programmed cell death in nematode Caenorhabditis elegans. We found that a selective inhibitor of ICE/ced 3 family proteases, benzyloxycarbonyl Asp CH2OC(O) 2 6,-dichlorobenzene (Z-Asp-CH2-DCB). completely blocked the apoptotic cell death of human leukemia cells caused by etoposide, camptothecin, 1-beta-D-arabinofuranosyl cytosine (Ara-C) and adriamycin. Moreover, in antitumor agent-treated U937 cells, an ICE-like (CPP32-like) protease was strongly activated. These results indicate that ICE/ ced 3 family proteases are involved in antitumor agent-induced apoptosis. Activation of ICE family proteases plays a key role in apoptosis. However, the subsequent mechanisms resulting in apoptosis are largely unknown. We identified actin as a substrate of ICE family proteases. Cleavage of actin and other substrate proteins by ICE family proteases could be critical in the ongoing process of antitumor agent-induced apoptosis in tumor cells.     

Language deficits, localization, and grammar: Evidence for a distributive model of language breakdown in aphasic patients and neurologically intact individuals.

Selective deficits in aphasic patients' grammatical production and comprehension are often cited as evidence that syntactic processing is modular and localizable in discrete areas of the brain (e.g., Y. Grodzinsky, 2000). The authors review a large body of experimental evidence suggesting that morphosyntactic deficits can be observed in a number of aphasic and neurologically intact populations. They present new data showing that receptive agrammatism is found not only over a range of aphasic groups, but is also observed in neurologically intact individuals processing under stressful conditions. The authors suggest that these data are most compatible with a domain-general account of language, one that emphasizes the interaction of linguistic distributions with the properties of an associative processor working under normal or suboptimal conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of pre-impact occupant postures and analysis of consequences on injury outcome. Part I: a driving simulator study

This paper considers pre-impact vehicle maneuvers and analyzes the resulting driver motion from their comfort seating position. Part I of this work consists of analyzing the driver behavior during a crash. The study is conducted using the LAMIH driving simulator and involves 76 participants. The emergency situation is created by a truck emerging from behind a tractor on the opposite side of the road and tearing along the participant. The driver positioning throughout the simulation is recorded via five video cameras allowing view of the front scene, the driver face, feet and pedals, hands on the steering wheel and global lateral view. Data related to braking force, seat pressure, muscular activity for major groups of muscles and actions on the steering wheel are also collected.The typical response to this type of emergency event is to brace rearward into the seat and to straighten the arms against the steering wheel, or, to swerve to attempt to avoid the impacting vehicle. While turning the steering wheel, the forearm can be directly positioned on the airbag module at time of crash which represents a potential injurious situation.These positions are used in Part II to determine scenario of positions for numerical simulation of a frontal collision.     

Baseline Determination in Construction Labor Productivity-Loss Claims

Various ways of quantifying damages have been applied to productivity loss claims in construction. All of the ways attempt to be as objective as possible based on the extent of information available in a particular case. The measured mile, a widely accepted method, is employed when an unimpacted baseline period of production can be identified. Although that approach is considered to be the most objective method available in such cases, the method is limited and does not directly account for variation in individual productivity values about a normal or natural level of productivity. A gap exists between the use of existing methods and the availability of an appropriate methodology that specifically addresses variation in productivity. The key lies in the way baseline productivity is measured, which is inherently statistical, yet no truly statistical methods are used to establish such a baseline. Using the measured mile as a backdrop, this article provides an objective, measurement-based approach that can be used to establish a productivity baseline applied to construction productivity loss claims, based on the application of statistical methods aided by a process control chart. The focus is on providing the basic principles and concepts underlying the approach presented.