Chronic thromboembolic pulmonary disease: Association with exercise-induced pulmonary hypertension and right ventricle adaptation over time

BACKGROUND AND AIM

Chronic thromboembolic pulmonary disease (CTEPD) is a progressive condition caused by fibrotic thrombi and vascular remodeling in the pulmonary circulation despite prolonged anticoagulation. We evaluated clinical factors associated with CTEPD, as well as its impact on functional capacity, pulmonary haemodynamics at rest and after exercise, and right ventricle (RV) morphology and function.

METHODS

We compared 33 consecutive patients with a history of acute pulmonary embolism and either normal pulmonary vascular imaging (negative Q-scan, group 1, n = 16) or persistent defects on lung perfusion scan (positive Q-scan) despite oral anticoagulation at 4 months (group 2, n = 17). Investigations included thrombotic load, the Pulmonary Embolism Severity Index (PESI) score, functional class, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), cardiopulmonary exercise test (CPET) and echocardiographic parameters at rest and after exercise (ESE), at 4 and at 24 months.

RESULTS

Compared with group 1, group 2 featured a higher PESI score (p = 0.02) and a higher thrombotic load (p = 0.004) at hospital admission. At 4 months, group 2 developed exercise-induced pulmonary hypertension (Ex-PH) at CPET (p < 0.001) and ESE (p < 0.001). At 24 months group 2 showed higher NT-proBNP (p < 0.001), WHO-FC (p < 0.001), systolic (p<0.001) and diastolic (p = 0.037) RV dysfunction and worse RV-arterial coupling (p < 0.001) despite maintaining a low or intermediate echocardiographic probability of PH.

CONCLUSIONS

This is the first "proof of concept" study showing that patients with a positive Q-scan frequently develop Ex-PH and RV functional deterioration as well as reduced functional capacity, generating the hypothesis that Ex-PH could help detect the progression to CTEPD.

Cardiovascular outcomes and molecular targets for the cardiac effects of Sodium-Glucose Cotransporter 2 Inhibitors: A systematic review

Sodium-glucose cotransporter 2 inhibitors (SGLT2i), a new class of glucose-lowering drugs traditionally used to control blood glucose levels in patients with type 2 diabetes mellitus, have been proven to reduce major adverse cardiovascular events, including cardiovascular death, in patients with heart failure irrespective of ejection fraction and independently of the hypoglycemic effect. Because of their favorable effects on the kidney and cardiovascular outcomes, their use has been expanded in all patients with any combination of diabetes mellitus type 2, chronic kidney disease and heart failure. Although mechanisms explaining the effects of these drugs on the cardiovascular system are not well understood, their effectiveness in all these conditions suggests that they act at the intersection of the metabolic, renal and cardiac axes, thus disrupting maladaptive vicious cycles while contrasting direct organ damage. In this systematic review we provide a state of the art of the randomized controlled trials investigating the effect of SGLT2i on cardiovascular outcomes in patients with chronic kidney disease and/or heart failure irrespective of ejection fraction and diabetes. We also discuss the molecular targets and signaling pathways potentially explaining the cardiac effects of these pharmacological agents, from a clinical and experimental perspective.

The Anthropocene Generalized: Evolution of Exo-Civilizations and Their Planetary Feedback

We present a framework for studying generic behaviors possible in the interaction between a resource-harvesting technological civilization (an exo-civilization) and the planetary environment in which it evolves. Using methods from dynamical systems theory, we introduce and analyze a suite of simple equations modeling a population which consumes resources for the purpose of running a technological civilization and the feedback those resources drive on the state of the host planet. The feedbacks can drive the planet away from the initial state the civilization originated in and into domains that are detrimental to its sustainability. Our models conceptualize the problem primarily in terms of feedbacks from the resource use onto the coupled planetary systems. In addition, we also model the population growth advantages gained via the harvesting of these resources. We present three models of increasing complexity: (1) Civilization-planetary interaction with a single resource; (2) Civilization-planetary interaction with two resources each of which has a different level of planetary system feedback; (3) Civilization-planetary interaction with two resources and nonlinear planetary feedback (i.e., runaways). All three models show distinct classes of exo-civilization trajectories. We find smooth entries into long-term, "sustainable" steady states. We also find population booms followed by various levels of "die-off." Finally, we also observe rapid "collapse" trajectories for which the population approaches n = 0. Our results are part of a program for developing an "Astrobiology of the Anthropocene" in which questions of sustainability, centered on the coupled Earth-system, can be seen in their proper astronomical/planetary context. We conclude by discussing the implications of our results for both the coupled Earth system and for the consideration of exo-civilizations across cosmic history. Key Words: Anthropocene-Astrobiology-Civilization-Dynamical system theory-Exoplanets-Population dynamics. Astrobiology 18, 503-518.

Regional point prevalence study of healthcare-associated infections and antimicrobial use in acute care hospitals in Liguria, Italy

BACKGROUND

Given the importance of monitoring healthcare-associated infections (HCAIs) and the consumption of antibiotics, a regional point prevalence survey was conducted in Liguria between March and April 2016.

AIM

To measure the overall prevalence of HCAI and describe the use of antibiotics in all public hospitals.

METHODS

Data on risk factors and use of antibiotics were collected for each hospitalized patient. To define the variables significantly associated with HCAI, univariate and multivariate analyses were conducted. Standardized infection ratio and standardized antimicrobial use ratio were measured for each participating hospital.

FINDINGS

A total of 3647 patients were enrolled. In all, 429 HCAIs were diagnosed in 376 patients, giving a prevalence of HCAI of 10.3%. Respiratory tract (21.7%) and urinary tract (20%) were the most frequent sites of infection. High rates of meticillin-resistant Staphylococcus aureus (47.4%) and Enterobacteriaceae resistant to carbapenems (26.3%) were isolated. Forty-six percent of patients received at least one antibiotic. Combinations of penicillins including β-lactamase inhibitors (24.1%) were the most widely used; the main indication (46.7%) was the treatment of a community-acquired infection.

CONCLUSION

There was an increase in HCAI prevalence compared to a similar survey conducted in 2007; however, the performance of overlapping investigations will enable more reliable considerations. Nevertheless, data on antimicrobial resistance and use of antibiotics are consistent with the national trend. Despite methodological limitations, prevalence studies are useful to monitor HCAI over time and encourage greater awareness of the problem by all stakeholders.

Multi-chamber microfluidic platform for high-precision skin permeation testing

The established in vitro tool used for testing the absorption and penetration of chemicals through skin in pharmacology, toxicology and cosmetic science is the static Franz diffusion cell. While widespread, Franz cells are relatively costly, low-throughput and results may suffer from poor reproducibility. Microfluidics has the potential to overcome these drawbacks. In this paper, we present a novel microfluidic skin permeation platform and validate it rigorously against the Franz cell by comparing the transport of 3 model chemicals of varying lipophilicity: caffeine, salicylic acid and testosterone. Permeation experiments through silicone membranes show that the chip yields higher sensitivity in permeant cumulative amounts and comparable or lower coefficients of variation. Using a skin organotypic culture, we show that the chip decreases the effect of unstirred water layers that can occur in static Franz cells. The validation reported herein sets the stage for efficient skin permeation and toxicity screening and further development of microfluidic skin-on-chip devices.

Immunochip analysis identifies novel susceptibility loci in the human leukocyte antigen region for acquired thrombotic thrombocytopenic purpura

Essentials Genetic predisposition to acquired thrombotic thrombocytopenic purpura (aTTP) is mainly unknown. Genetic risk factors for aTTP were studied by Immunochip analysis and replication study. Human leukocyte antigen (HLA) variant rs6903608 conferred a 2.5-fold higher risk of developing aTTP. rs6903608 and HLA-DQB1*05:03 may explain most of the HLA association signal in aTTP. Click to hear Dr Cataland's presentation on acquired thrombotic thrombocytopenic purpura SUMMARY: Background Acquired thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening thrombotic microangiopathy associated with the development of autoantibodies against the von Willebrand factor-cleaving protease ADAMTS-13. Similarly to what has been found for other autoimmune disorders, there is evidence of a genetic contribution, including the association of the human leukocyte antigen (HLA) class II complex with disease risk. Objective To identify novel genetic risk factors in acquired TTP. Patients/Methods We undertook a case-control genetic association study in 190 European-origin TTP patients and 1255 Italian healthy controls by using the Illumina Immunochip. Replication analysis in 88 Italian cases and 456 controls was performed with single-nucleotide polymorphism (SNP) TaqMan assays. Results and conclusion We identified one common variant (rs6903608) located within the HLA class II locus that was independently associated with acquired TTP at genome-wide significance and conferred a 2.6-fold increased risk of developing a TTP episode (95% confidence interval [CI] 2.02-3.27, P = 1.64 × 10-14 ). We also found five non-HLA variants mapping to chromosomes 2, 6, 8 and X that were suggestively associated with the disease: rs9490550, rs115265285, rs5927472, rs7823314, and rs1334768 (nominal P-values ranging from 1.59 × 10-5 to 7.60 × 10-5 ). Replication analysis confirmed the association of HLA variant rs6903608 with acquired TTP (pooled P = 3.95 × 10-19 ). Imputation of classic HLA genes followed by stepwise conditional analysis revealed that the combination of rs6903608 and HLA-DQB1*05:03 may explain most of the HLA association signal in acquired TTP. Our results refined the association of the HLA class II locus with acquired TTP, confirming its importance in the etiology of this autoimmune disease.

Physical activity, sleep pattern and energy expenditure in double-handed offshore sailing

AIM

The aim of the present study was to quantify total energy expenditure, activity energy expenditure and time spent at three levels of physical activity (low, moderate, high intensity) in four two-person crews during a 500-mile double-handed sailing regatta.

METHODS

Physical activity intensity and energy expenditure were assessed during a 500-nautical-mile double-handed offshore competition in eight male sailors (46.3±3.4 years; 180±13 cm; 85.4±12.5 kg). During the whole regatta, they wore an activity monitor that estimated energy expenditure and minutes spent at each level of intensity (sedentary, <1.5 METs; light physical activity, 1.5-2.9 METs; moderate physical activity, 3.0-6.0 METs; vigorous physical activity, >6.0 METs).

RESULTS

The sailors spent longer periods (P<0.0001) of time in sedentary (823±193 min/day) and light physical activities (516±177 min/day) than in moderate (95±34 min/day) or vigorous (6±4 min/day) physical activities. They slept 5 times per day (±1.4) for 36 min (±9) in each sleeping period. The total energy expenditure was 14.26±1.89 MJ/day and the activity energy expenditure was 5.06±1.42 MJ/day. Activity energy expenditure was significantly correlated with total sleep time, boat speed, and distance covered each day (P<0.05). CONCLUSION;:The high total energy expenditure was more likely a consequence of the short and rare periods of sleep during the competition rather than of the bouts of moderate and vigorous physical activities.

Two patients with history of STEC-HUS, posttransplant recurrence and complement gene mutations

Hemolytic uremic syndrome (HUS) is a disease of microangiopathic hemolytic anemia, thrombocytopenia and acute renal failure. About 90% of cases are secondary to infections by Escherichia coli strains producing Shiga-like toxins (STEC-HUS), while 10% are associated with mutations in genes encoding proteins of complement system (aHUS). We describe two patients with a clinical history of STEC-HUS, who developed end-stage renal disease (ESRD) soon after disease onset. They received a kidney transplant but lost the graft for HUS recurrence, a complication more commonly observed in aHUS. Before planning a second renal transplantation, the two patients underwent genetic screening for aHUS-associated mutations that revealed the presence of a heterozygous CFI mutation in patient #1 and a heterozygous MCP mutation in patient #2, and also in her mother who donated the kidney. This finding argues that the two cases originally diagnosed as STEC-HUS had indeed aHUS triggered by STEC infection on a genetic background of impaired complement regulation. Complement gene sequencing should be performed before kidney transplantation in patients who developed ESRD following STEC-HUS since they may be undiagnosed cases of aHUS, at risk of posttransplant recurrence. Furthermore, genetic analysis of donors is mandatory before living-related transplantation to exclude carriers of HUS-predisposing mutations.

Physical fitness before and after weight restoration in anorexia nervosa

AIM

The aims of this paper were: 1) to evaluate the feasibility of test for evaluating physical fitness (PF) in patients with anorexia nervosa (AN); 2) to investigate the effects of nutritional rehabilitation in this population of patients; and 3) to compare their level of fitness scores (at baseline and after weight restoration) with an age-matched healthy control group.

METHODS

PF was assessed with an adapted version of the Eurofit Physical Fitness Test Battery (EPFTB) administered to 37 consecutive female AN patients, at baseline and after weight restoration, and to 57 healthy age-matched females.

RESULTS

The inpatient treatment, based on cognitive behavior therapy, was associated with a significant improvement in BMI (from 14.5±1.5 to 18.8±1.1, P<0.001) and in 5 out of 6 EPFTB tests (P<0.05) in the AN group. However, both in pre and post, AN patients showed significant lower EPFTB than the control group (all P<0.001) with the exception of the Sit-Up score.

CONCLUSION

Results indicated that PF is lower in AN patients than in controls both at baseline and after weight restoration. Future studies should evaluate if the inclusion of an individualized health-enhancing physical activity program might improve the restoration of physical fitness.

The dangerous synergism between influenza and Streptococcus pneumoniae and innovative perspectives of vaccine prevention

Secondary bacterial pneumonia, particularly sustained by Streptococcus pneumoniae (Sp), represents an important cause of excess mortality during both influenza epidemics and pandemics. The lethal synergism between influenza virus and Sp was first suggested by studies performed on samples collected during autopsy from victims of 1918 influenza pandemic, and recently confirmed by data collected during the 2009 A/H1N1v influenza pandemic. Moreover, researches carried out in animal model contributed to partially clarify the pathogenic mechanisms underlying the synergism between these two etiological agents. Since 2000, a seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in the US, and in the following year in Europe, determining substantial and almost immediate benefits in terms of reduction of invasive pneumococcal disease (IPD) in both vaccinated children and adults through induction of herd protection. Furthermore, several researches have recently demonstrated the capacity of the PCV7 to prevent community-acquired pneumonia (CAP) and, in particular, influenza-associated pneumonia hospitalisations among children. Taking into account the above-mentioned positive results obtained with PCV7, the availability of a new generation of conjugate pneumococcal vaccine with an enlarged antigenic spectrum (i.e. PCV13) offers promising perspectives, to improve the control of influenza through the protection offered against its major complications, particularly CAP, not only in children, but also among adults.

History and evolution of influenza vaccines

Since the isolation of influenza virus in 1933, a great deal of work was carried out in order to develop influenza vaccines and improve these fundamental tools of prevention in terms of production, quality control, safety and tolerability, and immunogenicity. The paper summarizes the cornerstones of the continuous evolution of influenza vaccines and the most recent and promising developments in this field.

@Prevention: a website project for prevention in the healthcare setting

In the field of prevention, Internet websites and their related instruments constitute valuable tools for healthcare facilities, and particularly for Local Healthcare Authorities (LHA). As yet, however, their undoubted potential remains largely unexploited. Many LHA websites currently operating in Italy are organized in such a way that they fail to make adequate use of this precious resource. Indeed, communication regarding prevention is all too often limited to the simple reproduction of information and indications in a static and heterogeneous manner, so much so that it resembles a mere "online notice-board". The aim of the present research was to analyze the current situation and the various innovative proposals that have been made, in order to construct a more effective website model that could be used nationwide. To this end, the research was carried out through a two-pronged approach: on the one hand, all 190 LHA websites in Italy were analyzed; on the other, a questionnaire was administered to a sample of habitual users of the most modern and widespread social network, Facebook. Analysis and elaboration of the data gathered led to the creation of the model "@Prevention". This project is intended to introduce an innovative perspective into the field of online communication for healthcare prevention by providing a highly useful tool for the LHA, healthcare workers and, obviously, citizens.

[Outcome and survival of pediatric Short Bowel Syndrome (SBS)]

INTRODUCTION

SBS is the main cause of intestinal failure (IF) in children and has a high morbility and mortality.

OBJECTIVES

to analyze factors associated with the outcome and survival of SBS children.

METHODS

analytical, descriptive and retrospective study. We include patients with residual bowel length (RBL) ≤ 40 cm. OUTCOME is analyzed in groups: dead (D), adapted (A), parenteral nutrition dependant (NPD), and transplanted (Tx) according to: bowel anatomy, diagnosis, prematurely, year of beginning of IF, duration of IF, cholestasis (CB > 2 mg/dl) and thrombosis. Survival is analyzed with Kaplan Meier.

RESULTS

63 patients were included: RBL x 21 ± 11 cm, preserved colon 46%, prematures 41%, neonatal resection 78%, duration of IF x 0.66 years. 54% had cholestasis (CB x 5.29 ± 2.35 mg/dl) and 25% had thrombosis.

OUTCOME

D 33%, A 27%, PND 30% and Tx 10%. Adapted patients had longer RBL (p 0.001) and more preserved colon (p 0.017). 1 year survival was 86%, 2 years 70% and 3 years 66%. Age at death: x 2.3 years. Causes of death: hepatic failure 62%, lack of venous access 19%, sepsis 10%, others 10%. Factors related to death were shorter RBL (p 0.045), cholestasis (0.049, admittance to the center before 2000 (p 0.02).

CONCLUSIONS

SBS had a high mortality and 1/3 of patients could adapt requiring up to 5 years. Adaptation was in relation to anatomic factors. Mortality was related to.

Impact of alcohol consumption on winter sports-related injuries

INTRODUCTION

This study was carried out to evaluate data about trauma-related winter sports, including risk factors such as high speed, gender, age, alcohol consumption, details about the accident and snow conditions.

METHODS

A retrospective review was conducted to determine the injury patterns and crash circumstances in holiday skiers and snowboarders. The data recorded were obtained from the database of the Pre-Hospital Emergency Registry of six skiing areas in the Dolomite mountains during the winter seasons November 2004-May 2009, injury data for major traumas from Ski Patrol Injury reports (helicopter, ambulance or ski slopes' patrol reports), and intrahospital Emergency Department data. Alcohol concentration in blood was detected in 200 individuals suffering from major trauma.

RESULTS

A total of 4550 injured patients, predominantly male (69%), mean age 22 years (range 16-72), were included in the observational analysis. Knee, wrist and shoulder injuries were frequently associated with major thoracic, abdominal or head traumas (64% of cases). Suboptimal technical level, high speed, low concentration, snow or weather conditions, faulty equipment and protective devices were among the various causes of accidents. The analysis revealed that high alcohol blood concentration was present in 43% of 200 patients.

CONCLUSIONS

Even though the major causes of accidents were excessive speed, excessive fatigue, technical errors and bad weather conditions, alcohol abuse was often discovered. Random sampling and a non-systematic detection of alcohol blood levels likely led to an underestimation of alcohol consumption-related injuries. It is recommended that investigations into alcoholic intoxication in injured skiers should be carried out on a large scale.

Reaction center and light-harvesting I genes from Rhodopseudomonas capsulata

Five structural genes coding for the reaction center (RC) L, M, and H subunits and the two light-harvesting (LH) I polypeptides, B870alpha and B870beta, have been mapped on two restriction fragments from the R-prime plasmid pRPS404. It has been recently shown that enhanced near-infrared fluorescence mutants of Rhodopseudomonas capsulata typically lack RC or LH I polypeptides and that these lesions are marker-rescued by two restriction fragments from the R-prime plasmid: the 7.5-kilobase-pair EcoRI F fragment and the 4.75-kilobase-pair BamHI C-EcoRI fragment. We have now determined the nucleotide sequence of two restriction fragments and have found that the BamHI C-EcoRI B fragment carries the structural genes for the RC L and M subunits and both LH I polypeptides. Forty kilobase pairs away from this locus, the BamHI F fragment (within the EcoRI F fragment) carries the RC H subunit. The structural genes on the BamHI C-EcoRI B fragment are probably transcribed as part of a polycistronic mRNA. All of the structural genes begin with a consensus Shine-Dalgarno sequence and separate AUG start codons, indicating that the structural polypeptides are not cleaved from larger precursor polypeptides.

A long-term review of 50 patients out of 506 treated with automated percutaneous nucleotomy according to Onik for lumbar-sacral disc herniation

At the Orthopaedics and Traumatology Unit of the Palmanova Hospital, between 27 October 1989 and 31 December 2003 we performed 506 automated percutaneous nucleotomies according to Onik for the treatment of lumbar disc hernia. The survey of 50 reviewed cases after evaluation of the subjective and objective clinical pictures according to the Cabot method allowed us to come to the conclusion that this percutaneous methodology is suitable to relieve damaged discs from compression. It is also well accepted by patients because it is not too traumatic, it requires short-term hospitalisation, presents no risk of post-operative fibrosis and does not create complications for the eventual traditional operation when unsuccessful. It is extremely important to accurately select the candidates keeping in mind the original indications given by Onik for percutaneous discectomy for which--in case of contained disc herniation--leg pain (sciatalgia) is more severe than low back pain affecting the lumbar region.

Biomonitoring: Integration of biological end-points into chemical monitoring

Biomonitoring is currently performed at two levels, assessing exposure to pollutants and effects monitoring by bioassays. As an example for the first approach, vitellogenin (VTG) in male fish of Abramis brama as an endpoint for estrogen exposure is discussed. However, similar changes of VTG or VTG-like proteins in the hemolymph of mussels could not be detected. Enzyme-linked receptor assays for monitoring estrogenic effects at the molecular level serve as an example for the second category. Applications of the enzyme-linked receptor assay (ELRA) developed in our laboratory are presented. Detection limits of 0.02 μg/l 17β-estradiol were recently achieved with the chemiluminescent format. Although effect monitoring provides information in terms of toxicity equivalents, it is not possible to relate the signals to specific pollutants and their concentrations. For this purpose, chemical analysis is required. New approaches are reported for the direct coupling of bioassays and chemical analysis. This concept is defined as bioresponse-linked instrumental analysis. It combines biomolecular recognition, initiating a biological effect, and chemical analysis. In addition to the classical bioanalytical approaches, new strategies in genomics and proteomics have been developed. This may lead to multimarker approaches opening this area to environmental analytics.

[Comparison between Greenbaum's parabulbar anesthesia and Ripart's subtenon anesthesia in the anterior segment surgery]

PURPOSE

To compare two methods of sub-tenon anesthesia in 80 surgical procedures (phakoemulsification, glaucoma and combined surgery) in a prospective, single-surgeon study.

MATERIALS AND METHODS

Forty patients requiring anterior segment surgery in each eye were randomised to receive subtenon anaesthesia by either Greenbaum's method (using a flexible plastic cannula) or Ripart's method (using a 23G hypodermic needle). Randomization dictated the mode of anaesthesia for the first eye, the other technique being used for the second eye. Anaesthesia consisted of 1.5ml lidocaïne 2% and 1.5ml bupivacaïne 0.5% in all cases, and was performed by the same surgeon (EDLM) immediately before surgery. Type of surgical procedure, duration, complications, presence of sub-conjunctival haemorrhage, were assessed by the surgeon, who also graded chemosis (0-3), nuclear hardness (1-4), and ocular akinesia (0-2) for each patient. Pain was scored subjectively by each patient (0-10) during the injection, peroperatively and postoperatively.

RESULTS

Chemosis was significatively higher with Greenbaum's method than Ripart's method (p<0.01) and was sometimes undesirable for the surgeon. There was no difference in the pain score during the injection, preoperatively or postoperatively. Pain was usually very light and did not correlate with the duration of surgery. There was no akinesia in the majority of cases with either method, but the surgeon was sometimes limited by the akinesia of the medial rectus muscle and often by that of the inferior rectus muscle with elevation of the globe.

CONCLUSION

Greenbaum's method and Ripart's method are two subtenon anesthesic techniques characterized by an immediate, intense and prolonged analgesia (sometimes 60mn). Complete akinesia is rare and this is sometimes limiting. Chemosis was more often associated with Greenbaum's method, but Ripart's method carries the potential for needle-related complications.

Recombinational and mutagenic repair of psoralen interstrand cross-links in Saccharomyces cerevisiae

Psoralen photoreacts with DNA to form interstrand cross-links, which can be repaired by both nonmutagenic nucleotide excision repair and recombinational repair pathways and by mutagenic pathways. In the yeast Saccharomyces cerevisiae, psoralen cross-links are processed by nucleotide excision repair to form double-strand breaks (DSBs). In yeast, DSBs are repaired primarily by homologous recombination, predicting that cross-link and DSB repair should induce similar recombination end points. We compared psoralen cross-link, psoralen monoadduct, and DSB repair using plasmid substrates with site-specific lesions and measured the patterns of gene conversion, crossing over, and targeted mutation. Psoralen cross-links induced both recombination and mutations, whereas DSBs induced only recombination, and monoadducts were neither recombinogenic nor mutagenic. Although the cross-link- and DSB-induced patterns of plasmid integration and gene conversion were similar in most respects, they showed opposite asymmetries in their unidirectional conversion tracts: primarily upstream from the damage site for cross-links but downstream for DSBs. Cross-links induced targeted mutations in 5% of the repaired plasmids; all were base substitutions, primarily T --> C transitions. The major pathway of psoralen cross-link repair in yeast is error-free and involves the formation of DSB intermediates followed by homologous recombination. A fraction of the cross-links enter an error-prone pathway, resulting in mutations at the damage site.

The crystal structures of psoralen cross-linked DNAs: drug-dependent formation of Holliday junctions

The single-crystal structures are presented for two DNA sequences with the thymine bases covalently cross-linked across the complementary strands by 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT). The HMT-adduct of d(CCGCTAGCGG) forms a psoralen-induced Holliday junction, showing for the first time the effect of this important class of chemotheraputics on the structure of the recombination intermediate. In contrast, HMT-d(CCGGTACCGG) forms a sequence-dependent junction. In both structures, the DNA duplex is highly distorted at the thymine base linked to the six-member pyrone ring of the drug. The psoralen cross-link defines the intramolecular interactions of the drug-induced junction, while the sequence-dependent structure is nearly identical to the native Holliday junction of d(CCGGTACCGG) alone. The two structures contrast the effects of drug- and sequence-dependent interactions on the structure of a Holliday junction, suggesting a role for psoralen in the mechanism to initiate repair of psoralen-lesions in mammalian DNA.

[Ergonomic approach to risk control]

The aim of the paper is to emphasise the role and the importance of the ergonomic approach to improve reduction and management of the risk related to repetitive strain injuries. The authors tried to select and to put in evidence the risk factors related to the investigated problem, proposing a critical analysis of them, and to detect some guide lines to design or correct workplaces and tasks. These guidelines are based on ergonomic principles and they aim at reducing the risk related to repetitive strain injuries. The proposed interventions are grouped by a risk-factor criterion.

Acute fuel selection in response to high-sucrose and high-starch meals in healthy men

BACKGROUND

Despite considerable controversy over the inclusion of sucrose in the diets of people with diabetes, the acute metabolism of sucrose is not completely understood.

OBJECTIVE

Our objective was to investigate the metabolism of the monomeric constituents of sucrose after a high-sucrose meal.

DESIGN

Three test meals were consumed in a randomized, crossover design by 7 healthy male volunteers. Two of the meals were high in sucrose; one was supplemented with 200 mg uniformly labeled [13C]fructose and one was supplemented with 200 mg [13C]glucose. The other meal was high in starch, supplemented with 200 mg [13C]glucose. Fifty percent of energy was supplied as sucrose in the high-sucrose meals and as starch in the high-starch meal. Breath (13)CO(2) enrichment was measured at 15-min intervals and indirect calorimetry was performed for five 20-min sessions immediately before and during a 6-h postprandial period.

RESULTS

Carbohydrate oxidation rates rose much faster after the high-sucrose meals than after the high-starch meal. Breath (13)CO(2) enrichment rose faster and peaked earlier and at a higher value when [13C]fructose rather than [13C]glucose was given with the high-sucrose test meal. Values for breath (13)CO(2) enrichment from [13C]glucose after the high-starch meal were intermediate.

CONCLUSIONS

These results show that fructose is preferentially oxidized compared with glucose after a high-sucrose meal and that glucose is oxidized more slowly after a high-sucrose meal than after a high-starch meal.

Rhodobacter capsulatus DNA topoisomerase I purification and characterization

A 30-kDa DNA topoisomerase has been purified to near homogeneity from the purple nonsulfur photosynthetic bacterium Rhodobacter capsulatus. The enzyme is recognized by an antibody against a 16-mer peptide sequence from human DNA topoisomerase I. The purified enzyme is a type I topoisomerase. Consistent with the properties of other prokaryotic type I DNA topoisomerases, the isolated enzyme is unable to relax positively supercoiled DNA and absolutely requires divalent cations for its relaxation activity. However, regardless of the Mg+2 concentrations, ATP concentrations above 5 mM completely inhibit the relaxing activity. The enzyme is sensitive to high salt concentrations and the optimal activity occurs at salt concentrations between 3 and 30 mM for monovalent cations. Single-stranded M13 DNA is a strong inhibitor of this relaxing activity. The enzyme is inhibited by ethidium bromide, confirming that this DNA topoisomerase is incapable of relaxing positive supercoils. Topoisomerase I-specific inhibitors like Hoechst 32258 and actinomycin D inhibit the enzymatic activity while the enzyme is resistant to type II topoisomerase inhibitors such as norfloxacin, nalidixic acid, and novobiocin. From these enzymatic characteristics, we conclude that the R. capsulatus DNA topoisomerase is a prokaryotic type I DNA topoisomerase.

Comparative study of the analgesic efficacy of flurbiprofen and diclofenac in patients following excimer laser photorefractive keratectomy

This randomized, patient-masked, crossover trial compared the analgesic efficacy of flurbiprofen and diclofenac in 16 patients following excimer laser photorefractive keratectomy. Patients were randomly assigned to receive one study medication after surgery on the first eye and the other medication after surgery on the second eye (approximately 30 days later). After both surgeries, patients instilled one drop of the assigned medication six times daily for the first 3 days postsurgery and one drop four times daily on postsurgery days 4 through 7. Patients assessed the intensity of postsurgical pain beginning at postsurgery hour 5 and pain relief beginning at postsurgery hour 8 and continued to do so daily thereafter. On the last day (day 7), patients rated the global efficacy of the analgesic treatment. All assessments were performed by patients using descriptor and visual ordinal scales and were recorded in diaries. Patients were queried as to the presence, severity, and duration of any adverse events. Flurbiprofen produced significantly greater reductions in pain intensity than did diclofenac at all evaluations through day 4 and significantly greater relief of pain than did diclofenac at all evaluations through day 3. Significantly more patients treated with flurbiprofen reported being pain free on days 3 and 4 (11 [69%] and 16 [100%], respectively) compared with those treated with diclofenac (3 [19%] and 9 [56%], respectively). Based on patient ratings, flurbiprofen had significantly better global analgesic activity than diclofenac. Both treatments were well tolerated. Mild and transient ocular burning after instillation was the only reported adverse event; it was reported by all patients in both study groups at approximately 50% of study visits.

The local repressor AcrR plays a modulating role in the regulation of acrAB genes of Escherichia coli by global stress signals

Genes acrAB encode a multidrug efflux pump in Escherichia coli. We have previously reported that transcription of acrAB is increased under general stress conditions (i.e. 4% ethanol, 0.5 M NaCl, and the stationary phase in Luria-Bertani medium). In this study, lacZ transcriptional fusions and an in vitro gel mobility shift assay have been utilized to study the mechanisms governing the regulation of acrAB. We found that a closely linked gene, acrR, encoded a repressor of acrAB. Nevertheless, the general stress conditions increased transcription of acrAB in the absence of functional AcrR, and such conditions surprisingly increased the transcription of acrR even more strongly than that of acrAB. These results suggest that the general-stress-induced transcription of acrAB is primarily mediated by global regulatory pathway(s), and that one major role of AcrR is to function as a specific secondary modulator to fine tune the level of acrAB transcription and to prevent the unwanted overexpression of acrAB. To our knowledge, this represents a novel mechanism of regulating gene expression in E. coli. Evidence also suggests that the up-regulation of acrAB expression under general stress conditions is not likely to be mediated by the known global regulators, such as MarA or SoxS, although elevated levels of these proteins were shown to increase the transcription of acrAB.

Genes acrA and acrB encode a stress-induced efflux system of Escherichia coli

Defined mutations of acrA or acrB (formerly acrE) genes increased the susceptibility of Escherichia coli to a range of small inhibitor molecules. Deletion of acrAB increased susceptibility to cephalothin and cephaloridine, but the permeability of these beta-lactams across the outer membrane was not increased. This finding is inconsistent with the earlier hypothesis that acrAB mutations increase drug susceptibility by increasing the permeability of the outer membrane, and supports our model that acrAB codes for a multi-drug efflux pump. The natural environment of an enteric bacterium such as E. coli is enriched in bile salts and fatty acids. An acrAB deletion mutant was found to be hypersusceptible to bile salts and to decanoate. In addition, acrAB expression was elevated by growth in 5 mM decanoate. These results suggest that one major physiological function of AcrAB is to protect E. coli against these and other hydrophobic inhibitors. Transcription of acrAB is increased by other stress conditions including 4% ethanol, 0.5 M NaCl, and stationary phase in Luria-Bertani medium. Finally, acrAB expression was shown to be increased in mar (multiple-antibiotic-resistant) mutants.

Functional assignment of Erwinia herbicola Eho10 carotenoid genes expressed in Escherichia coli

Erwinia herbicola is a nonphotosynthetic bacterium that is yellow pigmented due to the presence of carotenoids. When the Erwinia carotenoid biosynthetic genes are expressed in Escherichia coli, this bacterium also displays a yellow phenotype. The DNA sequence of the plasmid pPL376, carrying the entire Erwinia carotenoid gene cluster, has been found to contain 12 open reading frames (ORFs). Six of the ORFs have been identified as carotenoid biosynthesis genes that code for all the enzymes required for conversion of farnesyl pyrophosphate (FPP) to zeaxanthin diglucoside via geranylgeranyl pyrophosphate, phytoene, lycopene, beta-carotene, and zeaxanthin. These enzymatic steps were assigned after disruption of each ORF by a specific mutation and analysis of the accumulated intermediates. Carotenoid intermediates were identified by the absorption spectra of the colored components and by high pressure liquid chromatographic analysis. The six carotenoid genes are arranged in at least two operons. The gene coding for beta-carotene hydroxylase is transcribed in the opposite direction from that of the other carotenoid genes and overlaps with the gene for phytoene synthase.

Structural analysis of c-myc in human sporadic colorectal carcinomas

Analysis of the DNA extracted from the colonic mucosa of 13 patients operated for colorectal carcinoma revealed c-myc rearrangements in three of them. In all cases, the alterations were found both in the histologically normal and in the tumoral mucosa. In one case, a different pattern of rearrangements characterized the two tissues. In all three individuals, the c-myc sequences appeared to be amplified. We suggest that c-myc rearrangements in the histologically normal colonic mucosa of colorectal carcinoma patients could represent a predisposition factor for the development of additional neoplasms.

Dynamic analysis of ventricular repolarization duration from 24-hour Holter recordings

Evaluation of the influence of the autonomic nervous system on the ventricular repolarization duration was carried out using beat-to-beat analysis of the time intervals between the peaks of the R and T waves (RTm). After pre-processing of digitized Holter ECG's, auto and cross spectrum analyses were applied to heart rate and repolarization duration variability signals. Coherence analysis was used to assess the existence of common spectral contributions. The heart rate variability signal was used as reference of the sympatho-vagal balance at the sinus node. It was found that, in normal individuals, the autonomic nervous system directly influences the ventricular repolarization duration and that this influence is qualitatively very similar to the one that modulates the heart rate. Pathological alteration of these parallel autonomic activities to the heart (on the sinus node and on the ventricle) might cause uncoupling between depolarization and repolarization.

Molecular cloning and characterization of acrA and acrE genes of Escherichia coli

The DNA fragment containing the acrA locus of the Escherichia coli chromosome has been cloned by using a complementation test. The nucleotide sequence indicates the presence of two open reading frames (ORFs). Sequence analysis suggests that the first ORF encodes a 397-residue lipoprotein with a 24-amino-acid signal peptide at its N terminus. One inactive allele of acrA from strain N43 was shown to contain an IS2 element inserted into this ORF. Therefore, this ORF was designated acrA. The second downstream ORF is predicted to encode a transmembrane protein of 1,049 amino acids and is named acrE. Genes acrA and acrE are probably located on the same operon, and both of their products are likely to affect drug susceptibilities observed in wild-type cells. The cellular localizations of these polypeptides have been analyzed by making acrA::TnphoA and acrE::TnphoA fusion proteins. Interestingly, AcrA and AcrE share 65 and 77% amino acid identity with two other E. coli polypeptides, EnvC and EnvD, respectively. Drug susceptibilities in one acrA mutant (N43) and one envCD mutant (PM61) have been determined and compared. Finally, the possible functions of these proteins are discussed.