Out-of-plane multilayer-dielectric-grating compressor for ultrafast Ti:sapphire pulses.

Extreme heat loads on optics, in particular the final pulse compression gratings, are a major hurdle to overcome in the ongoing push towards high average power (kW) and high repetition rate (kHz) operation of terawatt-class Ti:sapphire lasers. Multilayer dielectric (MLD) diffraction gratings have been suggested as a potential alternative to traditionally gold-coated compressor gratings, which are plagued by high energy absorption in the top gold layer. However, to support the required bandwidth (and ultimately the desired pulse duration) with MLD gratings, the gratings have to be operated in an out-of-plane geometry near the Littrow angle. Here, we report on the design of an MLD-based out-of-plane test compressor and a matching custom stretcher. We present a full characterization of the MLD compressor, focusing on its spectral transmission and the significance of laser pulse polarization in the out-of-plane geometry. To demonstrate compression of 40 µJ pulses centered at 800 nm wavelength to 26 fs pulse duration, we use the compressor with an MLD and gold grating configuration, and fully characterize the compressed pulses. Extrapolating our results indicates that MLD-grating-based out-of-plane compressors can support near-transform-limited pulses with sub-30 fs duration and good quality, demonstrating the viability of this concept for kW-level ultrafast Ti:sapphire laser systems.

Dose effects of tricyclic antidepressants in the treatment of acute depression - A systematic review and meta-analysis of randomized trials.

BACKGROUND: Tricyclic antidepressants (TCA) continue to be an important group of drugs, but it is unclear whether a dose-response relationship is supported by high-level evidence. METHODS: Systematic review in the Cochrane Collaboration's Central Register of Controlled Trials (CENTRAL) of studies randomizing patients to at least two doses of one TCA, complemented by searches in Medline, Embase, and PsycInfo. In multilevel regression, we calculated the standardized mean difference (SMD) in antidepressant efficacy per mg TCA dose increase, and we analyzed drop-outs due to adverse events. Finally, we computed random effects meta-analyses of all dose comparisons investigated in a minimum of two studies. RESULTS: Out of 5365 studies screened, we included 15 randomized trials on 24 comparisons of 14 different dose contrasts. We found a statistically non-significant positive effect of increasing the dose: 0.34 SMD with 100 mg/d dose increase ([-0.03; 0.70] p = 0.073). While several comparisons showed no clear signal of a dose gradient, 300 mg of imipramine/desipramine is statistically significantly superior to 150 mg (SMD: 0.80 [0.28; 1.33], p = 0.003, I2: 0%). Drop-outs increased with higher doses, albeit not statistically significantly: Odds ratio (OR) of 1.44 with 100 mg dose increase [0.54; 3.86]. Overall, risk of bias was high. LIMITATIONS: Limited number of studies with mainly high risk of bias. CONCLUSIONS: So far, data on a dose-response relationship in TCAs from direct dose comparisons are inconclusive. Clinically, escalation to high doses may be justified if side effects are bearable.

Dose-Response Relationship in Selective Serotonin and Norepinephrine Reuptake Inhibitors in the Treatment of Major Depressive Disorder: A Meta-Analysis and Network Meta-Analysis of Randomized Controlled Trials.

INTRODUCTION: Selective serotonin and norepinephrine reuptake inhibitors (SNRI) are among the most prescribed antidepressants, and dose escalation is a frequently applied strategy after non-response to an initially prescribed dose. OBJECTIVE: This meta-analysis aimed to find evidence of a dose-response relationship or to the contrary in direct comparisons of different SNRI doses in patients with major depressive disorder. METHODS: A systematic literature search for RCTs comparing at least two doses of SNRIs was carried out in CENTRAL, PubMed, PsycINFO, and EMBASE. Doses were classified as high, medium, and low according to manufacturers' product monographs and analyses at the level of SNRIs as a group and for single substances, accompanied by sensitivity network meta-analyses (Prospero CRD42018081031). RESULTS: From 2,070 studies screened, we included 26 studies with a total of 10,242 patients. Comparisons of medium versus low and high versus medium doses resulted in clinically and statistically non-significant standardized mean differences of -0.06 (-0.16 to 0.04) and -0.06 (-0.16 to 0.03) in favor of higher doses. In the analyses of single substances, no statistically significant results emerged, and many contrasts yielded very small effect sizes. Dropouts due to side effects tended to be more frequent with higher doses. Heterogeneity was low. Network meta-analyses of direct comparisons supported the findings, as did a risk of bias analysis. CONCLUSION: Based on the lack of positive evidence for a dose-response relationship in SNRIs as a group and in single SNRIs, we recommend prescribing medium doses. In case of insufficient response, we do not recommend increasing the dose of SNRIs.

Dose Increase Versus Unchanged Continuation of Antidepressants After Initial Antidepressant Treatment Failure in Patients With Major Depressive Disorder: A Systematic Review and Meta-Analysis of Randomized, Double-Blind Trials.

OBJECTIVE: To evaluate the efficacy and tolerability of dose increase compared to dose continuation of the initially prescribed antidepressant in antidepressant treatment failure (ATF). DATA SOURCES: We searched CENTRAL, PubMed, Embase, and PsycINFO using generic terms for depression, dose increase, and randomized controlled trials (RCTs), without date or language restrictions. STUDY SELECTION: Of 1,780 studies screened, 9 studies reporting on 1,273 patients were included for meta-analysis (PROSPERO Registration: CRD42017058389). Studies met the following predetermined inclusion criteria: randomized controlled trial, patients diagnosed with unipolar depression according to a standardized diagnostic instrument, ATF after a standard antidepressant trial (duration of ≥ 3 weeks at a standard dose), dose increase regimen, and control group of dose continuation. DATA EXTRACTION: Two authors extracted data independently according to the Cochrane Handbook for Systematic Reviews. Analyses are based on random effects models. RESULTS: All studies reported on selective serotonin reuptake inhibitors (SSRIs); 1 study also reported on maprotiline. Meta-analyses resulted in a statistically nonsignificant summary effect size of 0.053 standardized mean difference (95% CI, -0.143 to 0.248) in favor of antidepressant dose increase. Subgroup and sensitivity analyses and secondary outcome analyses resulted in similar effect estimates and supported the robustness of the results. CONCLUSIONS: With clinically and statistically nonsignificant effect estimates, there is evidence from RCTs against increasing the dose of SSRIs (with the possible exception of citalopram) in adult patients with major depression and ATF. Dose increase with other antidepressants (eg, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, monoamine oxidase inhibitors) and in other patient groups (minor depression, children and adolescents) or after long periods of first-line antidepressant therapy (ie, 8 weeks) have not been or not been sufficiently studied and, at this time, cannot be recommended in clinical practice.

Suicides and Suicide Attempts during Long-Term Treatment with Antidepressants: A Meta-Analysis of 29 Placebo-Controlled Studies Including 6,934 Patients with Major Depressive Disorder.

BACKGROUND: It is unclear whether antidepressants can prevent suicides or suicide attempts, particularly during long-term use. METHODS: We carried out a comprehensive review of long-term studies of antidepressants (relapse prevention). Sources were obtained from 5 review articles and by searches of MEDLINE, PubMed Central and a hand search of bibliographies. We meta-analyzed placebo-controlled antidepressant RCTs of at least 3 months' duration and calculated suicide and suicide attempt incidence rates, incidence rate ratios and Peto odds ratios (ORs). RESULTS: Out of 807 studies screened 29 were included, covering 6,934 patients (5,529 patient-years). In total, 1.45 suicides and 2.76 suicide attempts per 1,000 patient-years were reported. Seven out of 8 suicides and 13 out of 14 suicide attempts occurred in antidepressant arms, resulting in incidence rate ratios of 5.03 (0.78-114.1; p = 0.102) for suicides and of 9.02 (1.58-193.6; p = 0.007) for suicide attempts. Peto ORs were 2.6 (0.6-11.2; nonsignificant) and 3.4 (1.1-11.0; p = 0.04), respectively. Dropouts due to unknown reasons were similar in the antidepressant and placebo arms (9.6 vs. 9.9%). The majority of suicides and suicide attempts originated from 1 study, accounting for a fifth of all patient-years in this meta-analysis. Leaving out this study resulted in a nonsignificant incidence rate ratio for suicide attempts of 3.83 (0.53-91.01). CONCLUSIONS: Therapists should be aware of the lack of proof from RCTs that antidepressants prevent suicides and suicide attempts. We cannot conclude with certainty whether antidepressants increase the risk for suicide or suicide attempts. Researchers must report all suicides and suicide attempts in RCTs.

Effects of activated Bt transgene products (Cry1Ab, Cry3Bb) on immature stages of the ladybird Adalia bipunctata in laboratory ecotoxicity testing.

Insect-active Bacillus thuringiensis (Bt) proteins are expressed by several transgenic crop plants to control certain pests, but nontarget organisms such as ladybirds also can be exposed to these proteins in the field. We developed an improved ecotoxicity testing protocol and conducted feeding trials in a laboratory setting to test for possible adverse effects of different concentrations of microbially produced trypsin-activated Cry1Ab and Cry3Bb toxins on the coccinellid Adalia bipunctata. Larval/pupal mortality, development time, and overall body mass accumulation were recorded. Even at the lowest concentration (5 microg/ml), A. bipunctata larvae fed with the lepidopteran-active Cry1Ab toxin exhibited significantly higher mortality than the control group. In experiments with the coleopteran-active Cry3Bb, only a concentration of 25 microg/ml resulted in a marginally significantly higher mortality compared to the control. Both experiments revealed a slight decline in mortality at the highest concentration of 50 microg/ml, though this was statistically significant only in the Cry1Ab treatment. No differences were detected for development time and body mass of newly emerged adults. Dilutions of the expression vector pBD10--used as a control to exclude effects of the toxin production method--at concentrations between 10 and 100 microg/ml revealed no significant effects on either of the studied parameters. This suggests that the increased mortality of larvae in the toxin feeding trials was caused directly by the activated Bt toxins and raises questions regarding their commonly postulated specificity and their mode of action in A. bipunctata. Implications of the reported results for ladybird populations and their biological pest control functions in transgenic crop ecosystems are discussed.

Small-vessel stents for intracranial angioplasty: in vitro comparison of different stent designs and sizes by using CT angiography.

BACKGROUND AND PURPOSE: Our purpose was to evaluate whether CT angiography is a suitable alternative to conventional angiography in the evaluation of small-vessel stents for intracranial angioplasty. METHODS: CT angiographic appearances of 23 stents of different designs and sizes (2.0, 3.0, and 4.0 mm) were investigated after they were filled with a solution of 0.9% NaCl or diluted contrast medium. For each stent, artificial lumen narrowing (ALN) was measured, and the difference in the number of pixels with a Hounsfield value below 200 HU between the two filling states, DIFF(HU<200), was calculated to provide an objective indicator of the size of the evaluable stent diameter. RESULTS: With a window width of 1500 HU at a window level of 400 HU, ALN ranged from 66.8% to 97.7% in the group of 2.0-mm stents and from 38.6% to 66.8% in the groups of 3.0- and 4.0-mm stents. For the 2.0-mm stents, DIFF(HU<200) was zero. In the groups of 3.0- and 4.0-mm stents, DIFF(HU<200) ranged from 0.3 to 6.7, corresponding to a diameter of 0.13-3.0 mm, when the pixel size was presupposed to be 0.449 mm. CONCLUSION: CT angiographic evaluation of small-vessel patency after stent placement is considerably impaired by ALN. Stent manufacturers should be aware of potential artifacts caused by their stents during noninvasive diagnostic studies such as CT angiography.