AXSIS: Exploring the frontiers in attosecond X-ray science, imaging and spectroscopy.

X-ray crystallography is one of the main methods to determine atomic-resolution 3D images of the whole spectrum of molecules ranging from small inorganic clusters to large protein complexes consisting of hundred-thousands of atoms that constitute the macromolecular machinery of life. Life is not static, and unravelling the structure and dynamics of the most important reactions in chemistry and biology is essential to uncover their mechanism. Many of these reactions, including photosynthesis which drives our biosphere, are light induced and occur on ultrafast timescales. These have been studied with high time resolution primarily by optical spectroscopy, enabled by ultrafast laser technology, but they reduce the vast complexity of the process to a few reaction coordinates. In the AXSIS project at CFEL in Hamburg, funded by the European Research Council, we develop the new method of attosecond serial X-ray crystallography and spectroscopy, to give a full description of ultrafast processes atomically resolved in real space and on the electronic energy landscape, from co-measurement of X-ray and optical spectra, and X-ray diffraction. This technique will revolutionize our understanding of structure and function at the atomic and molecular level and thereby unravel fundamental processes in chemistry and biology like energy conversion processes. For that purpose, we develop a compact, fully coherent, THz-driven atto-second X-ray source based on coherent inverse Compton scattering off a free-electron crystal, to outrun radiation damage effects due to the necessary high X-ray irradiance required to acquire diffraction signals. This highly synergistic project starts from a completely clean slate rather than conforming to the specifications of a large free-electron laser (FEL) user facility, to optimize the entire instrumentation towards fundamental measurements of the mechanism of light absorption and excitation energy transfer. A multidisciplinary team formed by laser-, accelerator,- X-ray scientists as well as spectroscopists and biochemists optimizes X-ray pulse parameters, in tandem with sample delivery, crystal size, and advanced X-ray detectors. Ultimately, the new capability, attosecond serial X-ray crystallography and spectroscopy, will be applied to one of the most important problems in structural biology, which is to elucidate the dynamics of light reactions, electron transfer and protein structure in photosynthesis.

OX40L blockade and allergen-induced airway responses in subjects with mild asthma.

BACKGROUND: The OX40/OX40L interaction contributes to an optimal T cell response following allergic stimuli and plays an important role in the maintenance and reactivation of memory T effector cells. OBJECTIVE: We tested whether treatment with an anti-OX40L monoclonal antibody (MAb) would inhibit allergen-induced responses in subjects with asthma. METHODS: Twenty-eight mild, atopic asthmatic subjects were recruited for a double-blind, randomized, placebo-controlled, parallel-group trial (ClinicalTrials.gov identifier NCT00983658) to compare blockade of OX40L using a humanized anti-OX40L MAb to placebo-administered intravenously in 4 doses over 3 months. Allergen inhalation challenges were carried out 56 and 113 days after the first dose of study drug. The primary outcome variable was the late-phase asthmatic response. Other outcomes included the early-phase asthmatic response, airway hyperresponsiveness, serum IgE levels, blood and sputum eosinophils, safety and tolerability. RESULTS: Treatment with anti-OX40L MAb did not attenuate the early- or late-phase asthmatic responses at days 56 or 113 compared with placebo. In the anti-OX40L MAb treatment group, total IgE was reduced 17% from pre-dosing levels, and sputum eosinophils decreased 75% by day 113 (both P = 0.04). There was no effect of anti-OX40L MAb on airway hyperresponsiveness or blood eosinophils. The frequency of AEs was similar in both groups. CONCLUSION AND CLINICAL RELEVANCE: Pharmacological activity of anti-OX40L MAb was observed by decreases in serum total IgE and airway eosinophils at 16 weeks post-dosing, but there was no effect on allergen-induced airway responses. It is possible that the treatment duration or dose of antibody was insufficient to impact the airway responses.

The effects of lebrikizumab in patients with mild asthma following whole lung allergen challenge.

BACKGROUND: Interleukin 13 (IL13) is a T-helper type 2 (Th2) cytokine associated with inflammation and pathology in allergic diseases such as bronchial asthma. We have shown that treatment with lebrikizumab, an anti-IL13 monoclonal antibody, significantly improves prebronchodilator forced expiratory volume in 1 s (FEV(1)) in a subset of subjects with uncontrolled asthma. OBJECTIVE: To evaluate efficacy and safety of lebrikizumab in subjects with mild asthma who underwent bronchial allergen challenge. METHODS: Twenty-nine subjects were randomized 1 : 1-5 mg/kg lebrikizumab (n = 13) or placebo (n = 16) administered subcutaneously every 4 weeks over 12 weeks, a total of four doses. Primary efficacy outcome was late asthmatic response (LAR) at Week 13, defined as area under the curve of FEV1 measured 2-8 h following inhaled allergen challenge. Serum biomarkers were measured to verify IL13 pathway inhibition and identify patients with an increased response to lebrikizumab. RESULTS: At Week 13, the LAR in lebrikizumab subjects was reduced by 48% compared with placebo subjects, although this was not statistically significant (95% confidence interval, -19%, 90%). Exploratory analysis indicated that lebrikizumab-treated subjects with elevated baseline levels of peripheral blood eosinophils, serum IgE, or periostin exhibited a greater reduction in LAR compared with subjects with lower baseline levels of these biomarkers. Lebrikizumab exerted systemic effects on markers of Th2 inflammation, reducing serum immunoglobulin E (IgE), chemokine ligands 13 and 17 by approximately 25% (P < 0.01). Lebrikizumab was well tolerated. CONCLUSION AND CLINICAL RELEVANCE: Lebrikizumab reduced the LAR in subjects with mild asthma. Clinical trial number NCT00781443.

Pulse synthesis in the single-cycle regime from independent mode-locked lasers using attosecond-precision feedback.

We report the synthesis of a nearly single-cycle (3.7 fs), ultrafast optical pulse train at 78 MHz from the coherent combination of a passively mode-locked Ti:sapphire laser (6 fs pulses) and a fiber supercontinuum (1-1.4 µm, with 8 fs pulses). The coherent combination is achieved via orthogonal, attosecond-precision synchronization of both pulse envelope timing and carrier envelope phase using balanced optical cross-correlation and balanced homodyne detection, respectively. The resulting pulse envelope, which is only 1.1 optical cycles in duration, is retrieved with two-dimensional spectral shearing interferometry (2DSI). To our knowledge, this work represents the first stable synthesis of few-cycle pulses from independent laser sources.

Differences between perspectives of physicians and patients on anticoagulation in patients with atrial fibrillation: observational study.

OBJECTIVE: To determine and compare physicians' and patients' thresholds for how much reduction in risk of stroke is necessary and how much risk of excess bleeding is acceptable with antithrombotic treatment in people with atrial fibrillation. DESIGN: Prospective observational study. SETTING: Tertiary and peripheral referral centres in Nova Scotia, Canada. PARTICIPANTS: 63 physicians who were treating patients with atrial fibrillation and 61 patients at high risk for atrial fibrillation. MAIN OUTCOME MEASURES: Participants underwent a face to face interview with a probability trade-off tool. Thresholds were determined for the minimum reduction in risk of stroke necessary and the maximum increase in risk of excess bleeding acceptable for treatment with aspirin and warfarin in people with atrial fibrillation. RESULTS: The minimum number of strokes that needed to be prevented in 100 patients over two years for warfarin to be justified was significantly lower for patients than for physicians (1.8 (SD 1.9) v 2.5 (1.6), P=0.009), whereas for aspirin there was no difference between patients and physicians (1.3 (1.3) v 1.6 (1.5), P=0.29). The maximum number of excess bleeds acceptable in 100 patients over two years for use of warfarin and aspirin was significantly higher for patients than for physicians (warfarin 17.4 (7.1) v 10.3 (6.1); aspirin 14.7 (8.5) v 6.7 (6.2); P<0.001 for both comparisons). CONCLUSIONS: Patients at high risk for atrial fibrillation placed more value on the avoidance of stroke and less value on the avoidance of bleeding than did physicians who treat patients with atrial fibrillation. The views of the individual patient should be considered when decisions are being made about antithrombotic treatment for people with atrial fibrillation.

Physician characteristics in relation to cardiovascular drugs commonly prescribed for hypertension in Nova Scotia.

BACKGROUND: Cardiovascular drugs are the most frequently prescribed class of drugs in Canada. Among them, drugs used to treat hypertension are the single largest component. Variability in how these drugs are prescribed should be based on the specific characteristics of patients. However, some evidence shows that physician characteristics can also play a substantial role in prescribing trends. Such variation is also associated with varying beneficial and adverse patient outcomes. PURPOSE: To determine whether prescribing patterns of drugs used to treat hypertension in elderly patients in Nova Scotia varied by physician characteristics. METHODS: A retrospective, population-based descriptive study was done using the Nova Scotia Pharmacare program data for the fiscal year 1995/96. The unit of analysis was the individual physician. All drugs indicated in the management of hypertension were included for the analysis. RESULTS: Of 1466 physicians included in the analysis, 1004 were family physicians (FPs) and/or general practitioners (GPs), 155 were internal medicine specialists and 307 were other specialists. Fifty-eight per cent of 103,193 eligible senior citizens received at least one of the study medications. FPs and/or GPs prescribed 95.9% of all the study drugs. Internists prescribed proportionately fewer angiotensin-converting enzyme inhibitors, thiazides and other diuretics compared with the FPs and/or GPs but more beta-blockers and calcium channel blockers. A large proportion of the FPs and/or GPs (55.3%) prescribed less than 10% of the total day's supply of drugs, whereas a small proportion of FPs and/or GPs (16.3%) prescribed 52.6% of all the study drugs. There was no variation in the distribution of the types of antihypertensives prescribed based on physician age, sex or volume of prescribing. A slight variation in prescribing was seen with location of practice. CONCLUSIONS: Patterns of prescribing cardiovascular drugs used to treat hypertension were remarkably unaffected by physician characteristics. This finding counters other evidence in the literature that has raised concerns over prescribing patterns of certain types of physicians. Prescribing patterns may vary for other drug classes, but for this group of antihypertensives, little variability was found.

Efficient new ribozyme mimics: direct mapping of molecular design principles from small molecules to macromolecular, biomimetic catalysts.

Dramatic improvements in ribozyme mimics have been achieved by employing the principles of small molecule catalysis to the design of macromolecular, biomimetic reagents. Ribozyme mimics derived from the ligand 2,9-dimethylphenanthroline (neocuproine) show at least 30-fold improvements in efficiency at sequence-specific RNA cleavage when compared with analogous o-phenanthroline- and terpyridine-derived reagents. The suppression of hydroxide-bridged dimers and the greater activation of coordinated water by Cu(II) neocuproine (compared with the o-phenanthroline and terpyridine complexes) better allow Cu(II) to reach its catalytic potential as a biomimetic RNA cleavage agent. This work demonstrates the direct mapping of molecular design principles from small-molecule cleavage to macromolecular cleavage events, generating enhanced biomimetic, sequence-specific RNA cleavage agents.

Asthma in primary care: making guidelines work.

OBJECTIVE: To determine the views of family physicians regarding selected asthma recommendations from a Canadian practice guideline and the supporting evidence, and to identify issues needing further development if family physicians are to find guideline recommendations to be truly useful clinical tools. SETTING: Four urban communities in Nova Scotia, Prince Edward Island and New Brunswick. PARTICIPANTS: Twenty community family physicians representing different practice settings, and varying according to age and sex, were recruited to participate. DATA COLLECTION: Four focus groups were held, each lasting 2 h, at which recommendations from a published asthma guideline were presented for discussion on the applicability to their practices. The data were analyzed using a grounded theory method. RESULTS: Physicians rely on clinical judgment in lieu of objective measures in diagnosing asthma and resist treating every exacerbation with steroids. They thought that the recommendations on smoking and patient education should have been stronger or more prominent. Patient noncompliance limits the usefulness of home peak flow measures. Topics such as allergy assessment and most pharmacological therapies triggered little discussion. DISCUSSION: Asthma guideline developers and those interested in enhancing compliance with recommendations will need to attend to factors such as physician attitudes and beliefs on a variety of issues, including the use of objective measures and the availability of adequate resources to conduct the tests. Similarly, negative patient attitudes toward an increased use of corticosteroids suggest that a public education program would be most helpful regarding that group of recommendations.

Prescribing exercise for cardiac patients: knowledge, practices, and needs of family physicians and specialists.

PURPOSE: To determine the following about prescribing exercise for cardiac patients: physicians' present and needed knowledge; their present practices; barriers that hinder them; and perceived need for and content of a protocol for prescribing exercise. METHODS: (1) Questionnaire mailed to 371 family physicians (FPs), 31 internists, and 25 cardiologists; and (2) four focus groups consisting of 25 FPs, 1 internist, and 3 cardiologists. RESULTS: Questionnaire response rate was 45% (n = 192). Because responses were similar and the group was small, internists and cardiologists were combined as "specialists." Generally, questionnaire data agreed with focus group data, with the latter providing more detail. Family physicians perceived they know little about prescribing a specific exercise program while specialists perceived they know little about motivating patients to begin an exercise program. The method most frequently used by both physician groups to increase exercise is providing general advice. The main barriers to prescribing exercise were inadequate knowledge (FPs only), patient education materials, and community resources. Both groups rated highly the need for a protocol for prescribing exercise and indicated it should: (1) include identification of patient's stage of change; (2) include indications and contraindications for exercise; (3) provide guidelines for developing a specific exercise prescription; (4) contain patient education materials, and (5) be simple and short. CONCLUSIONS: Family physicians perceive they know little about prescribing a specific exercise program for cardiac patients while specialists perceive they know little about motivating patients. Physicians rate highly the need for a protocol to help them prescribe exercise for cardiac patients.

Cyclosporin use in the precolectomy chronic ulcerative colitis patient: a community experience and its relationship to prospective and controlled clinical trials. Pacific Northwest Gastroenterology Society.

OBJECTIVE: To define what effect seminal and controlled clinical trials have on practice patterns within a gastroenterological community. To define whether these practice patterns reproduce reported treatment methods and whether results comparable with those reported in such trials are noted within a community practice setting. METHODS: Mailed surveies, with telephone follow-up, were sent to all members of the Pacific Northwest Gastroenterology Society. Respondents were queried regarding cyclosporin use in the precolectomy chronic ulcerative colitis (CUC) patient. Data collected included patient demographics, disease duration and extent, pre-treatment use of steroids, method, dosage, and duration of cyclosporin therapy, side effects, and short-term and subsequent clinical results. RESULTS: Twenty-one percent of 81 respondents had used cyclosporin for precolectomy CUC, approximately one-half using constant infusion and one-half using parenteral bolus therapy. Side effects attributed to the cyclosporin were noted in eight of 30 patients (27%), and acute colectomy was avoided in 17 patients (57%). Subsequent colectomy was required in an additional nine patients (73% total) within a 6-month follow-up period, a significantly higher colectomy rate than that reported in prospective trials. CONCLUSIONS: Potential reasons precluding cyclosporin use within the gastroenterological community may include lack of knowledge about cyclosporin therapy for CUC, lack of opportunity, skepticism, fear of medication side effects, survey sampling error, or treatment philosophy. Potential reasons for failure to duplicate the results reported in controlled trials are more complex but may include inadequate treatment duration the learning curve associated with the use of a new medication, or acceptance of colectomy as the treatment of choice in patients with acutely or chronically debilitating disease.

Bile duct diverticula and webs: nonspecific cholangiographic features of primary sclerosing cholangitis.

Biliary tree diverticula and webs are considered by several authors to be specific cholangiographic features of primary sclerosing cholangitis (PSC). Our experience suggested that these findings can be seen in patients without PSC. The purpose of this study was twofold: to establish whether diverticula and webs are indeed specific for PSC and to assess whether PSC can be accurately diagnosed without reference to diverticula or webs. We retrospectively reviewed 861 consecutive ERCP studies and found 32 cases of webs and/or diverticula. Using accepted cholangiographic, clinical, and histologic criteria, we diagnosed PSC in nine patients and excluded it in 21, with two instances of uncertain diagnoses. Webs and diverticula seen in PSC were cholangiographically indistinguishable from those in the group without PSC. All 21 patients without PSC had other biliary abnormalities, and were grouped by the predominant abnormality or finding believed to be associated with diverticulum or web formation: common duct stones or cholangitis (n = 11 patients), postoperative stricture (n = 4), bile duct stent and balloon dilatation (n = 3), malignant stricture (n = 2), and choledochoduodenostomy (n = 1). To assess cholangiographic diagnosis of PSC in these patients, a blinded reviewer studied the radiographs of the 30 patients with diverticula and/or webs who had confirmed diagnoses. By using established radiologic criteria alone (ignoring diverticula and webs), the correct diagnosis was made in 27, yielding a sensitivity of 89% and specificity of 91%. We conclude that the presence of diverticula and/or webs on a cholangiogram is a nonspecific finding and may be due to inflammation or trauma to the bile duct wall. Further, PSC can be distinguished from other abnormalities on the basis of findings other than diverticula and webs.

Endoscopic laser lithotripsy of large bile duct stones.

Experimental work has established that the Candela (Candela Laser Corporation, Wayland, MA) flashlamp excited dye laser (wavelength, 504 nm) is a highly effective method for fragmenting biliary stones and has minimal potential for injuring the bile duct wall. This technique was evaluated in 25 complex patients whose stones, usually because of large size, did not respond to standard nonoperative treatment. The laser imaging was applied through a quartz fiber and aimed either under direct vision with choledochoscopes passed percutaneously or through a special "mother" duodenoscope or under fluoroscopic guidance at standard duodenoscopy. Laser treatment resulted in some fragmentation of stones in 23 cases. Subsequently, it proved that it was possible to clear the bile duct of stones in 20 patients, 12 of them receiving successful treatment during the same endoscopic procedure. There were no significant complications. This endoscopic technique seems to be a useful new alternative to surgery in patients with large and difficult bile duct stones.

Inhibitory regulation of rat exocrine pancreas by peptide YY and pancreatic polypeptide.

Peptide YY (PYY) and pancreatic polypeptide (PP) have been shown to inhibit exocrine pancreatic secretion in vivo in a variety of species. This study evaluates the type of stimulation inhibited by PYY and PP by examining, in urethan-anesthetized rats, the inhibition of pancreatic secretion when stimulated to a comparable extent by cholecystokinin (CCK), 2-deoxy-D-glucose (2DG), bethanecol, and electrical vagal nerve stimulation. PYY at maximal infusion rates inhibited stimulation by CCK by 83%, bethanecol by 55%, and electrical nerve stimulation by 40%. The inhibition of CCK stimulation was half maximal at 250 pmol.kg-1.h-1. By contrast, PYY totally inhibited 2DG-stimulated secretion with half-maximal inhibition at 10 pmol. kg-1.h-1. PP acted similarly to PYY in inhibiting CCK and 2DG-stimulated pancreatic protein secretion but was fivefold weaker in each case. These findings indicate that PYY and PP have multiple actions but preferentially inhibit neurally mediated pancreatic secretion at a preacinar cell locus, possibly at a central site of action.

Gaucher's disease: a case history with extensive lipid storage in the brain.

Patients with acute infantile or type II neuropathic Gaucher's disease demonstrate neurologic deficits that are seemingly greater than the extent of the central nervous system involvement found at autopsy. Examination of the brain of an affected child shows widespread deposition of lipid in a pattern not recognized heretofore. Based on these observations, the authors hypothesize that widespread deposition of the Gaucher glucocerebroside elicits a mild tissue response, which functionally becomes highly significant.