Reactive organic carbon air emissions from mobile sources in the United States

Mobile sources are responsible for a substantial controllable portion of the reactive organic carbon (ROC) emitted to the atmosphere, especially in urban environments of the United States. We update existing methods for calculating mobile source organic particle and vapor emissions in the United States with over a decade of laboratory data that parameterize the volatility and organic aerosol (OA) potential of emissions from on-road vehicles, nonroad engines, aircraft, marine vessels, and locomotives. We find that existing emission factor information from Teflon filters combined with quartz filters collapses into simple relationships and can be used to reconstruct the complete volatility distribution of ROC emissions. This new approach consists of source-specific filter artifact corrections and state-of-the-science speciation including explicit intermediate-volatility organic compounds (IVOCs), yielding the first bottom-up volatility-resolved inventory of US mobile source emissions. Using the Community Multiscale Air Quality model, we estimate mobile sources account for 20 %-25 % of the IVOC concentrations and 4.4 %-21.4 % of ambient OA. The updated emissions and air quality model reduce biases in predicting fine-particle organic carbon in winter, spring, and autumn throughout the United States (4.3 %-11.3 % reduction in normalized bias). We identify key uncertain parameters that align with current state-of-the-art research measurement challenges.

2002-2017 anthropogenic emissions data for air quality modeling over the United States

The United States Environmental Protection Agency (US EPA) has developed a set of annual North American emissions data for multiple air pollutants across 18 broad source categories for 2002 through 2017. The sixteen new annual emissions inventories were developed using consistent input data and methods across all years. When a consistent method or tool was not available for a source category, emissions were estimated by scaling data from the EPA's 2017 National Emissions Inventory with scaling factors based on activity data and/or emissions control information. The emissions datasets are designed to support regional air quality modeling for a wide variety of human health and ecological applications. The data were developed to support simulations of the EPA's Community Multiscale Air Quality model but can also be used by other regional scale air quality models. The emissions data are one component of EPA's Air Quality Time Series Project which also includes air quality modeling inputs (meteorology, initial conditions, boundary conditions) and outputs (e.g., ozone, PM_2.5 and constituent species, wet and dry deposition) for the Conterminous US at a 12 km horizontal grid spacing.

Evaluation of 15 years of modeled atmospheric oxidized nitrogen compounds across the contiguous United States

Atmospheric nitrogen oxide and nitrogen dioxide (NO + NO2, together termed as NO X ) estimates from annual photochemical simulations for years 2002-2016 are compared to surface network measurements of NO X and total gas-phase-oxidized reactive nitrogen (NO Y ) to evaluate the Community Multiscale Air Quality (CMAQ) modeling system performance by U.S. region, season, and time of day. In addition, aircraft measurements from 2011 Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality are used to evaluate how emissions, chemical mechanism, and measurement uncertainty each contribute to the overall model performance. We show distinct seasonal and time-of-day patterns in NO X performance. Summertime NO X is overpredicted with bimodal peaks in bias during early morning and evening hours and persisting overnight. The summertime morning NO X bias dropped from between 28% and 57% for earlier years (2002-2012) to between -2% and 7% for later years (2013-2016). Summer daytime NO X tends to be unbiased or underpredicted. In winter, the evening NO X overpredictions remain, but NO X is unbiased or underpredicted overnight, in the morning, and during the day. NO X overpredictions are most pronounced in the Midwestern and Southern United States with Western regions having more of a tendency toward model underpredictions of NO X . Modeled NO X performance has improved substantially over time, reflecting updates to the emission inputs and the CMAQ air quality model. Model performance improvements are largest for years simulated with CMAQv5.1 or later and for emission inventory years 2014 and later, coinciding with reduced onroad NO X emissions from vehicles with newer emission control technologies and improved treatment of chemistry, deposition, and vertical mixing in CMAQ. Our findings suggest that emissions temporalization of specific mobile source sectors have a small impact on model performance, while chemistry updates improve predictions of NO Y but do not improve summertime NO X bias in the Baltimore/DC area. Sensitivity runs performed for different locations across the country suggest that the improvement in summer NO X performance can be attributed to updates in vertical mixing incorporated in CMAQv5.1.

Digital pen technology for conducting cognitive assessments: a cross-over study with older adults

Many digitalized cognitive assessments exist to increase reliability, standardization, and objectivity. Particularly in older adults, the performance of digitized cognitive assessments can lead to poorer test results if they are unfamiliar with the computer, mouse, keyboard, or touch screen. In a cross-over design study, 40 older adults (age M = 74.4 ± 4.1 years) conducted the Trail Making Test A and B with a digital pen (digital pen tests, DPT) and a regular pencil (pencil tests, PT) to identify differences in performance. Furthermore, the tests conducted with a digital pen were analyzed manually (manual results, MR) and electronically (electronic results, ER) by an automized system algorithm to determine the possibilities of digital pen evaluation. ICC(2,k) showed a good level of agreement for TMT A (ICC(2,k) = 0.668) and TMT B (ICC(2,k) = 0.734) between PT and DPT. When comparing MR and ER, ICC(2,k) showed an excellent level of agreement in TMT A (ICC(2,k) = 0.999) and TMT B (ICC(2,k) = 0.994). The frequency of pen lifting correlates significantly with the execution time in TMT A (r = 0.372, p = 0.030) and TMT B (r = 0.567, p < 0.001). A digital pen can be used to perform the Trail Making Test, as it has been shown that there is no difference in the results due to the type of pen used. With a digital pen, the advantages of digitized testing can be used without having to accept the disadvantages.

Economic evaluations of system-based obesity interventions - the case for a new approach

System-based interventions are of increasing interest as they seek to modify environments (e.g. socio-cultural system, transport system or policy system) that promote development of conditions such as obesity and its related risk factors. In our commentary, we draw attention to features of the system-based approach that may explain the relative absence of economic evaluations of the cost-effectiveness of these interventions, needed to guide decision-making on which to deploy. We present and discuss potentially applicable methods and alternative approaches based on our experiences in two major system-based interventions currently underway (in Melbourne, Australia and Gaggenau, Germany) that begin to fill this gap. We feel the issues and potential solutions outlined in this commentary are important for a broad range of stakeholders (e.g. clinicians, interventionalists, policy makers) to consider as they seek to address the issue of obesity.

Effect of Ambient Temperature on Total Organic Gas Speciation Profiles from Light-Duty Gasoline Vehicle Exhaust

Total organic gases (TOG) emissions from motor vehicles include air toxic compounds and contribute to formation of ground-level ozone and secondary organic aerosol (SOA). These emissions are known to be affected by temperature; however previous studies have typically focused only on the temperature dependence of total emission factors and select toxic compounds. This study builds on the previous research by performing an evaluation of a comprehensive set of gas-phase organic compounds present in gasoline motor vehicle exhaust. A fleet of five vehicles using port fuel injection engine technology and running on E10 fuel was tested. Overall, three temperatures (0, 20, and 75 °F; or -18, -7, and 24 °C), two driving conditions (urban-FTP75 and aggressive driving-US06) and 161 compounds were evaluated; the emissions distributions were used to construct speciation profiles for each driving cycle and temperature. Overall, the speciation results indicated a significant increase in alkane and methane content, and decrease in alcohol, aldehyde and ketone content with decreasing temperature. These were verified using a statistical significance test. The fraction and composition of Mobile Source Air Toxics (MSATs) were significantly affected by temperature for both driving cycles. The ozone forming potentials of these profiles were evaluated using the maximum incremental reactivity (MIR) scale. Aromatic content was predicted to be a major driver behind the ozone forming potentials. Additionally, the decreasing ozone potential could be attributed to increased methane fractions with increasing temperature.

Estimating the lifetime cost of childhood obesity in Germany: Results of a Markov Model

BACKGROUND

Child obesity is a growing public health concern. Excess weight in childhood is known to be associated with a high risk of obesity and obesity-related comorbidities in adulthood.

OBJECTIVES

This study quantifies lifetime excess costs of overweight and obese adults in Germany taking the history of obesity in childhood into account.

METHODS

A two-stage Markov cohort state transition model was developed. At stage 1, the distribution of body mass index (BMI) categories was tracked from childhood (ages 3-17) to adulthood (age 17 and up). Based on these results, it was distinguished whether adults had been normal in weight or overweight/obese as child. At stage 2, age-specific and lifetime costs from age 18 onwards were simulated in two further Markov cohort models, one for each of the two BMI groups. Model parameter values were obtained from the German Interview and Examination Survey for Children and Adolescents (KiGGS), the German Microcensus 2009 and published literature.

RESULTS

When compared with normal weight adults, lifetime excess costs are higher among adults who had been overweight or obese at any point during childhood. For 18-year-old women (men), who have been overweight/obese during their childhood (ages 3-17), undiscounted lifetime excess costs are estimated at €19,479 (€14,524), with 60% (67%) occurring beyond age 60. Discounted (3%) lifetime excess costs are considerably lower, amounting to €4262 for men and €7028 for women.

CONCLUSIONS

Because childhood obesity determines healthcare costs occurring in adulthood, interventions preventing the persistence of child obesity and obesity-related comorbidities during adulthood could have a substantial impact on reducing the burden of the obesity epidemic.

Association Strength of Three Adiposity Measures with Autonomic Nervous System Function in Apparently Healthy Employees

OBJECTIVES

To investigate the association of different measures of central (abdominal) and overall adiposity with autonomic nervous system (ANS) function, indexed by heart rate variability (HRV), in apparently healthy human adults.

DESIGN AND MEASUREMENTS

Cross-sectional data of 8,538 participants (20% female, age: 41 ± 11 years, body mass index (BMI): 24 ± 4 kg/m2, waist circumference (WC): 91 ± 12 cm, waist-to-height ratio (WHtR): 0.45 ± 0.08) were available for analysis.

RESULTS

All measures of adiposity were inversely correlated with vagally-mediated HRV indexed by RMSSD (all p<0.001). Strongest associations were found with WC and RMSSD (r = -0.29). Associations were stronger in males (WC r = -0.32) than in females (WC r = -0.23). Partial correlations revealed the same pattern for RMSSD (WC all pcc = -0.12 p<0.001; WC male pcc = -0.14 p<0.001; WC female pcc = -0.06 p<0.05). Correlation strength of BMI and WHtR with RMSSD were similar and significantly weaker compared to WC (p < .001) in unadjusted analysis. Overall, nonparametric Kendall's τb led to the same conclusions.

CONCLUSION

The present data supports previous findings, that HRV is related to measures of adiposity in healthy individuals. In line with previous research, we found that WC is more strongly related to measures of HRV, indicating that WC best captures adiposity related risk.

Metabolic profiles during an oral glucose tolerance test in pregnant women with and without gestational diabetes

BACKGROUND/AIM

Gestational diabetes (GDM) is a complex metabolic condition associated with hyperpglycemia that is diagnosed in an oral glucose tolerance test (OGTT) during pregnancy. For a deeper understanding of the pathology of the disease, further investigations during pregnancy are required, ideally under metabolic challenging conditions.

METHODS

We performed targeted metabolomics in a group of 24 well-matched women during an oral glucose tolerance test (OGTT). 231 plasma metabolites were profiled and compared to conventional clinical diagnostics.

RESULTS

A pattern of 8 metabolites differed between GDM and healthy controls as early as 30 min in an OGTT (AUC 0.977±0.008), and an increase in acylcarnitine C18:0, decreased concentrations of diacyl phosphatidylcholines (PC aa) C34:4, PC aa C36:4, PC aa C38:5, Lyso PC C20:4 and arachidonic acid were associated with insulin resistance.

CONCLUSION

Our data suggest an additional value of metabolite pattern in the diagnosis of GDM and describe altered pathways that might be subjected to a more precise diagnosis and individualized therapy.

[Off-label drug prescriptions among outpatient children and adolescents in Germany--a database analysis]

BACKGROUND

Due to lack of respective studies children often receive medication that is applied beyond the approved indication. The consequence of this off-label use is often an increased risk of unexpected and undesirable side effects. This study deals with the amount of off-label drug prescriptions among children and adolescents receiving outpatient treatment in Germany. The aim is to outline age-, gender-, region-, and insurance specific differences and to determine risk factors for an off-label prescription.

METHODS

This is a retrospective study that has been conducted by means of the IMS Patient Database Disease Analyzer for the year 2010 considering three therapy classes (analgesics, antibiotics and antidepressants). The evaluation of the risk factors for an off-label prescription resulted from a multivariate logistic regression. Age- and dose-specific prescriptions were analyzed but not indication-specific prescriptions.

RESULTS

In total 189,285 children and adolescents with analgesics-, 147,089 with antibiotics-, and 15,405 with antidepressants prescriptions were identified. The percentage of patients with off-label prescriptions amounted to 0.9 % for analgesics, 2.5 % for antibiotics and 8.5 % for antidepressants. The off-label prescriptions made by general practitioners were significantly higher than those made by pediatricians and child psychiatrists. The number of off-label prescriptions in country sides was higher than in cities. In eastern states more off-label prescriptions were made than in western states of Germany.

CONCLUSION

The study shows that outpatient treatment of children and adolescents occurs widely with drugs corresponding to age and dosage. Off-label prescriptions not conform to indication were not determined. However, off-label drug use should be reduced further for outpatient treatment to ensure a safe and low-risk medical treatment for children and adolescents.

The long-term cost-effectiveness of obesity prevention interventions: systematic literature review

Obesity prevention provides a major opportunity to improve population health. As health improvements usually require additional and scarce resources, novel health technologies (interventions) should be economically evaluated. In the prevention of obesity, health benefits may slowly accumulate over time and it can take many years before an intervention has reached full effectiveness. Decision-analytic simulation models (DAMs), which combine evidence from diverse sources, can be utilized to evaluate the long-term cost-effectiveness of such interventions. This literature review summarizes long-term economic findings (defined as ≥ 40 years) for 41 obesity prevention interventions, which had been evaluated in 18 cost-utility analyses, using nine different DAMs. Interventions were grouped according to their method of delivery, setting and risk factors targeted into behavioural (n=21), community (n=12) and environmental interventions (n=8). The majority of interventions offered good value for money, while seven were cost-saving. Ten interventions were not cost-effective (defined as >50,000 US dollar), however. Interventions that modified a target population's environment, i.e. fiscal and regulatory measures, reported the most favourable cost-effectiveness. Economic findings were accompanied by a large uncertainty though, which complicates judgments about the comparative cost-effectiveness of interventions.

Egeson's (George's) transtridecadal weather cycling and sunspots

In the late 19th century, Charles Egeson, a map compiler at the Sydney Observatory, carried out some of the earliest research on climatic cycles, linking them to about 33-year cycles in solar activity, and predicted that a devastating drought would strike Australia at the turn of the 20th century. Eduard Brückner and William J. S. Lockyer, who, like Egeson, found similar cycles, with notable exceptions, are also, like the map compiler, mostly forgotten. But the transtridecadal cycles are important in human physiology, economics and other affairs and are particularly pertinent to ongoing discusions of climate change. Egeson's publication of daily weather reports preceded those officially recorded. Their publication led to clashes with his superiors and his personal life was marked by run-ins with the law and, possibly, an implied, but not proven, confinement in an insane asylum and premature death. We here track what little is known of Egeson's life and of his bucking of the conventional scientific wisdom of his time with tragic results.

Determination of root canal curvatures before and after canal preparation (part II): A method based on numeric calculus

The aim of this paper is to present a new method based on numeric calculus to provide data on any type of root canal curvature at any point of the long axis of the canal. Twenty severely curved, simulated root canals were prepared with rotary FlexMaster and Profile instruments in the crown-down technique and manually in the step-back technique. The inner and outer curvatures were registered in a system of coordinates before and after preparation in increments of 0.5 mm. Using an equalising function, the curvatures were first represented in graphic and algebraic form. The maximum and the mean curvature as well as the length of the arc from the apical foramen to the point of maximum curvature were determined mathematically. An increase in maximum curvature was registered for all four shaping systems investigated. The radius of the inner curvature decreased by 0.5-1.2 mm in the manual systems as a result of the preparation. The Profile system displayed the smallest changes in radius (-0.9 mm) even with the outer curvature, and manual preparation with stainless steel files the most pronounced change (-1.8 mm). The point of maximum curvature at the inner curvature was displaced by 1.6 mm to the apical foramen through manual preparation with Ni-Ti files. At the outer curvature, the maximum displacement (1.8 mm) recorded was also the result of preparation with Ni-Ti hand files, while a displacement of only 0.3 mm to the apical foramen was recorded with the other systems. The method offers a means of determining curvatures precisely without random specification of reference points. The method is also capable of registering only minor changes in curvature in the two-dimensional long axis of the canal.

Determination of root canal curvatures before and after canal preparation (part 1): a literature review

The continuing development of methods and materials for root canal preparation is resulting in enhanced preparation techniques with only minor alterations to the canal morphology. Improved evaluation methods are required for differentiated assessment of these innovations. One criterion for assessment of the preparation quality of curved root canals is preparation-induced straightening of the canal. The first canal curvature measurements served to divide teeth into different curvature classes. However, their actual execution represented mere angular measurement rather than root curvature assessment. This purely graphic method lacked precision, nor could it be readily applied to all tooth groups. Further developments of that method resulted in it being applicable to molars and to canals with multiple curvatures. Some years ago, the graphically determined curvature radius was added as a further parameter to measurement of the canal deviation angle, thus permitting a curvature to be correctly described for the first time in geometric and analytic terms. The first mathematically accurate description was presented by Dobó-Nagy et al., who correctly described the mean canal curvature in a two-dimensional image in concrete terms by means of fourth-degree polynomial functions. Recent developments in the application of microcomputed tomography of extracted teeth permit non-destructive three-dimensional assessment of root canal configurations. It remains to be seen whether this resource-intensive form of in vitro examination can assert itself.

Das Leitlinien-Clearingverfahren COPD. Empfehlungen für eine nationale Leitlinie

In order to promote the care of patients with COPD in Germany a national guideline clearing project was initiated jointly by autonomous corporate bodies of the German health care system. Following a systematic search of literature data bases between 1992 and 2002, 20 guidelines were identified that met the inclusion criteria and were evaluated with the German Checklist for Methodological Guideline Appraisal. Following this, a multidisciplinary expert group appointed by the German Guideline Clearinghouse (Leitlinien-Clearingstelle im Arztlichen Zentrum fur Qualitat in der Medizin, AZQ) reviewed the suitability of these guidelines for the use in the German health care system. Referring to methodological aspects, criteria were best met by the guideline of the Veteran's Health Administration/Department of Defense (US), followed by the one of the Deutsche Atemwegsliga and the Deutsche Gesellschaft fur Pneumologie. Aiming at the production respectivly a revision of a German national guideline for COPD the expert group agreed on recommendations organized in 19 chapters. Among others these strengthened the role of a precise definition of COPD based primarily on the pathogenesis, of a subtle description of all diagnostic and therapeutic tools and of a detailed description of quality assurance and quality management. The feasability of recommendations were demonstrated by examples chosen from the evaluated guidelines. Additionally the presented findings may be used as steering tools in the German Health care system.

Root-canal shaping with manual and rotary Ni-Ti files performed by students

AIM

To investigate root-canal shaping with manual and rotary Ni-Ti files performed by students.

METHODOLOGY

Thirty undergraduate dental students prepared 150 simulated curved root canals in resin blocks with manual Ni-Ti files with a stepback technique and 450 simulated curved canals with rotary Ni-Ti files with a crowndown technique. Incidence of fracture, preparation length, canal shape and preparation time were investigated. Questionnaires were then issued to the students for them to note their experience of the two preparation methods.

RESULTS

Zips and elbows occurred significantly (P < 0.001) less frequently with rotary than with manual preparation. The correct preparation length was achieved significantly (P < 0.05) more often with rotary files than with manual files. Instrument fractures were recorded in only 1.3% of cases with both rotary and manual preparation. The mean time required for manual preparation was significantly (P < 0.001) longer than that required for rotary preparation. Prior experience with a hand preparation technique was not reflected in an improved quality of the subsequent rotary preparation. Approximately 83% of the students claimed to have a greater sense of security in rotary than in manual preparation. Overall 50% felt that manual and engine-driven preparation should be given equal status in undergraduate dental education.

CONCLUSIONS

Inexperienced operators achieved better canal preparations with rotary instruments than with manual files. No difference in fracture rate was recorded between the two systems.

Root canal shaping with manual stainless steel files and rotary Ni-Ti files performed by students

AIM

To investigate root canal shaping with manual stainless steel files and rotary Ni-Ti files by students.

METHODOLOGY

Two hundred and ten simulated root canals with the same geometrical shape and size in acrylic resin blocks were prepared by 21 undergraduate dental students with manual stainless steel files using a stepback technique or with rotary Ni-Ti files in crown-down technique. Preparation length, canal shape, incidence of fracture and preparation time were investigated.

RESULTS

Zips and elbows occurred significantly (P < 0.001) less frequently with rotary than with manual preparation. The correct preparation length was achieved significantly (P < 0.05) more often with rotary Ni-Ti files than with manual stainless steel files. Fractures occurred significantly (P < 0.05) less frequently with hand instrumentation. The mean time required for manual preparation was significantly (P < 0.001) longer than that required for rotary preparation. Prior experience with a hand preparation technique was not reflected in an improved quality of the subsequent engine-driven preparation.

CONCLUSIONS

Inexperienced operators achieved better canal preparations with rotary Ni-Ti instruments than with manual stainless steel files. However, rotary preparation was associated with significantly more fractures.

[Current initiatives in Germany for translating national guidelines into reality - a survey]

The role of practice guidelines as a tool for quality management in health care is now widely accepted in Germany- not only by health professionals, but also in politics. The physicians' professional associations as well as health care authorities (physicians' self-governmental bodies) and parliament introduced several incentives and regulations, aiming at a regular use of guidelines in health care. Among these the German guideline clearinghouse with the systematic approach towards identification, dissemination, and implementation of best available evidence-based guidelines, as well as the country-wide implementation of disease management guidelines seem to be effective and efficient in quality management as well as in patient care management in the German health care system. The article gives an overview on background, procedures and barriers to country-wide implementation of clinical practice guidelines within a social security health care system.

Gait with and without forearm crutches in patients with total hip arthroplasty

There is considerable variation between centres in the use of forearm crutches in the rehabilitation of patients with total hip arthroplasty who are capable of full weight bearing. This study aimed to compare the gait of patients with total hip arthroplasty walking with and without crutches. The gait analysis in 19 patients included the assessment of kinematics, kinetics and the kinesiological electromyographic activity of lower limb and trunk muscles. With the forearm crutches patients walked with a reduced cadence, a longer stride length and more symmetrically (P < 0.05). The activity of the gluteus medius, vastus medialis and lateralis, and erector spinae muscles of the affected and of the vastus medialis muscle of the unaffected side decreased significantly (P < 0.05). Furthermore, seven subjects displayed an abnormal activation pattern of the affected hip abductor when walking with forearm crutches, characterized by a second burst during swing (n = 5) or a tonic pattern (n = 2). It is concluded that the use of forearm crutches resulted in a symmetrical gait pattern. The reduced activity of relevant pelvi-trochanteric muscles and the disturbed activation pattern of the affected hip abductor when walking with crutches might indicate that patients should walk unaided as soon as possible to provide a more efficient muscular training under dynamic conditions.

[The gait of patients with full weightbearing capacity after hip prosthesis implantation on the treadmill with partial body weight support, during assisted walking and without crutches]

PROBLEM

Treadmill training with partial body weight support is a new promising technique in the rehabilitation in hip arthroplasty patients. With little data on the gait pattern and extent of pelvitrochanteric muscle activation, this study analysed the gait of hip arthroplasty patients walking on the treadmill and also during floor walking with and without crutches.

METHOD

Gait analysis in 19 hip arthroplasty patients capable of full weight bearing included the assessment of kinematics, kinetics and kinesiologic electromyogram of relevant trunk and lower limb muscles during treadmill walking with 15% of body weight support, and during floor walking with and without crutches at comparable walking velocities.

RESULTS

Both on the treadmill and with crutches, patients walked less frequent, with a longer stride and more symmetric as compared to the unaided gait. Both techniques, however, resulted in a reduced activation of most of the pelvitrochanteric muscles, particularly when using crutches. The comparison of both supporting methods revealed a higher activity of the M. gluteus medius of the affected side on the treadmill. The amount of body weight reduction was comparable ranging from 10 to 15%.

CONCLUSIONS

Treadmill training with constant body weight support enables hip arthroplasty patient to entrain a dynamic and symmetric gait pattern with a better activation of the hip abductor of the affected side as compared to walking with crutches. Nevertheless, the level of activation was less than when walking without crutches which, however, resulted in a limping gait pattern.

Substrate-specific selenoprotein B of glycine reductase from Eubacterium acidaminophilum. Biochemical and molecular analysis

The substrate-specific selenoprotein B of glycine reductase (PBglycine) from Eubacterium acidaminophilum was purified and characterized. The enzyme consisted of three different subunits with molecular masses of about 22 (alpha), 25 (beta) and 47 kDa (gamma), probably in an alpha 2 beta 2 gamma 2 composition. PBglycine purified from cells grown in the presence of [75Se]selenite was labeled in the 47-kDa subunit. The 22-kDa and 47-kDa subunits both reacted with fluorescein thiosemicarbazide, indicating the presence of a carbonyl compound. This carbonyl residue prevented N-terminal sequencing of the 22-kDa (alpha) subunit, but it could be removed for Edman degradation by incubation with o-phenylenediamine. A DNA fragment was isolated and sequenced which encoded beta and alpha subunits of PBglycine (grdE), followed by a gene encoding selenoprotein A (grdA2) and the gamma subunit of PBglycine (grdB2). The cloned DNA fragment represented a second GrdB-encoding gene slightly different from a previously identified partial grdBl-containing fragment. Both grdB genes contained an in-frame UGA codon which confirmed the observed selenium content of the 47-kDa (gamma) subunit. Peptide sequence analyses suggest that grdE encodes a proprotein which is cleaved into the previously sequenced N-terminal 25-kDa (beta) subunit and a 22-kDa (alpha) subunit of PBglycine. Cleavage most probably occurred at an -Asn-Cys- site concomitantly with the generation of the blocking carbonyl moiety from cysteine at the alpha subunit.

Various functions of selenols and thiols in anaerobic gram-positive, amino acids-utilizing bacteria

Electron transfer reactions for the reduction of glycine in Eubacterium acidaminophilum involve many selenocysteine (U)- and thiol-containing proteins, as shown by biochemical and molecular analysis. These include an unusual thioredoxin system (-CXXC-), protein A (-CXXU-) and the substrate-specific protein B of glycine reductase (-UXXCXXC-). Most probably a selenoether is formed at protein B by splitting the C-N-bond after binding of the substrate. The carboxymethyl group is then transferred to the selenocysteine of protein A containing a conserved motif. The latter protein acts as a carbon and electron donor by giving rise to a protein C-bound acetyl-thioester and a mixed selenide-sulfide bond at protein A that will be reduced by the thioredoxin system. The dithiothreitol-dependent D-proline reductase of Clostridium sticklandii exhibits many similarities to protein B of glycine reductase including the motif containing selenocysteine. In both cases proprotein processing at a cysteine residue gives rise to a blocked N-terminus, most probably a pyruvoyl group. Formate dehydrogenase and some other proteins from E. acidaminophilum contain selenocysteine, e.g., a 22 kDa protein showing an extensive homology to peroxiredoxins involved in the detoxification of peroxides.

Dioxin causes a sustained oxidative stress response in the mouse

Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD) is the prototype for environmental agonists of the aromatic hydrocarbon receptor (AHR) that are known to produce multiple adverse effects in laboratory animals as well as humans. Although not directly genotoxic, dioxin is known to increase transformation and mutations in mammalian cell culture and to cause an exaggerated oxidative stress response in the female rat. In humans and mice, however, dioxin-mediated oxidative stress appears to be more subtle, causing a response that has been poorly characterized. Using the female C57BL/6J inbred mouse, we show here that intraperitoneal treatment of 5 micrograms TCDD per kilogram on 3 consecutive days produces a striking, prolonged oxidative stress response: hepatic oxidized glutathione levels increase 2-fold within 1 week, and these effects persist for at least 8 weeks despite no further dioxin treatment. Urinary levels of 8-hydroxydeoxyguanosine--a product of DNA base oxidation and subsequent excision repair--remain elevated about 20-fold at 8 weeks after dioxin treatment, consistent with chronic and potentially promutagenic DNA base damage. These results demonstrate that dioxin exposure does produce a sustained oxidative stress response in the mouse.

A comparison of long term results of the standard Whipple procedure and the pylorus preserving pancreatoduodenectomy

The standard Whipple procedure involves intestinal disturbances, such as dumping, diarrhea, dyspeptic complaints and the occurrence of ulcers of the anastomoses. A postoperative weight loss was observed ranging between 10 and 40 kilograms. Only a few patients were able to compensate after several months. It was thought that preservation of the intact stomach would prevent the complications arising from a loss of gastric reservoir function and thus the malnutrition could be improved postoperatively. Between 1985 and March 1992, we performed the pylorus-preserving Whipple procedure and treated a group of 43 patients with this method. In the same period, 15 patients were operated upon with the standard Whipple procedure. The present evaluation of the accumulated patient data, including extensive functional studies, led to the following results comparing the pylorus preserving Whipple procedure with the standard Whipple procedure. First, the capacity for food uptake and the development of body weight postoperatively is significantly better. Second, gastric or jejunal ulcers were not observed. Third, there were no clinical signs of digestive disorders, such as different forms of dumping. Nutrition and digestion were not impeded by the preserved opening mechanism of the pylorus. Fourth, the postoperative exocrine function was only slightly decreased. Fifth, glucose metabolism postoperatively was influenced only slightly by preservation of the pylorus. In taking the results of all the examinations into consideration, it can be said that the restricted organ loss in the Whipple procedure with pylorus preservation leaves the secretory and functional capacity of the upper part of the gastrointestinal tract almost unchanged.

A member of a novel human DH gene family: DHFL16

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