Experimental generation of a flat-top beam profile in a stable ring cavity.

In this Letter, we present a spatially homogeneous field inside of a ring cavity that was created by combining two transverse modes generated by a single laser through modulation. The interference term between the two modes averages out because of the frequency difference that exists between them, eliminating the need for interferometric control of their relative phase. The use of a ring cavity allows for a large waist for the flat-top profile, big enough to cover the atoms in an atomic trap. The cavity is mechanically and thermally isolated, and the laser light is locked to the cavity using the Pound-Drever-Hall technique. The flat-top profile technique reported here fulfills the vanishing curvature criterion at the center of the profile.

Influence of implant strategy on the transition from temporary left ventricular assist device to durable mechanical circulatory support.

OBJECTIVES: Bridging from a temporary microaxial left ventricular assist device (tLVAD) to a durable left ventricular assist device (dLVAD) is playing an increasing role in the treatment of terminally ill patients with heart failure. Scant data exist about the best implant strategy. The goal of this study was to analyse differences in the dLVAD implant technique and effects on patient outcomes. METHODS: Data from 341 patients (19 European centres) who underwent a bridge-to-bridge implant from tLVAD to dLVAD between January 2017 and October 2022 were retrospectively analysed. The outcomes of the different implant techniques with the patient on cardiopulmonary bypass, extracorporeal life support or tLVAD were compared. RESULTS: A durable LVAD implant was performed employing cardiopulmonary bypass in 70% of cases (n = 238, group 1), extracorporeal life support in 11% (n = 38, group 2) and tLVAD in 19% (n = 65, group 3). Baseline characteristics showed no significant differences in age (P = 0.140), body mass index (P = 0.388), creatinine level (P = 0.659), the Model for End-Stage Liver Disease (MELD) score (P = 0.190) and rate of dialysis (P = 0.110). Group 3 had significantly fewer patients with preoperatively invasive ventilation and cardiopulmonary resuscitation before the tLVAD was implanted (P = 0.009 and P < 0.001 respectively). Concomitant procedures were performed more often in groups 1 and 2 compared to group 3 (24%, 37% and 5%, respectively, P < 0.001). The 30-day mortality data showed significantly better survival after an inverse probability of treatment weighting in group 3, but the 1-year mortality showed no significant differences among the groups (P = 0.012 and 0.581, respectively). Postoperative complications like the rate of right ventricular assist device (RVAD) implants or re-thoracotomy due to bleeding, postoperative respiratory failure and renal replacement therapy showed no significant differences among the groups. Freedom from the first adverse event like stroke, driveline infection or pump thrombosis during follow-up was not significantly different among the groups. Postoperative blood transfusions within 24 h were significantly higher in groups 1 and 2 compared to surgery on tLVAD support (P < 0.001 and P = 0.003, respectively). CONCLUSIONS: In our analysis, the transition from tLVAD to dLVAD without further circulatory support did not show a difference in postoperative long-term survival, but a better 30-day survival was reported. The implant using only tLVAD showed a reduction in postoperative transfusion rates, without increasing the risk of postoperative stroke or pump thrombosis. In this small cohort study, our data support the hypothesis that a dLVAD implant on a tLVAD is a safe and feasible technique in selected patients.

[Effect of latanoprost on ocular hemodynamics and contrast sensitivity]. / Einfluss von Latanoprost auf okuläre Hämodynamik und Kontrastsensitivität.

BACKGROUND: Latanoprost effectively lowers intraocular pressure. Because ischemia has gained increasing importance in the pathogenesis of glaucoma, an antiglaucomatous drug should also be investigated with regard to the influence on ocular hemodynamics. METHODS: In a double masked, randomized, clinical trial, Latanoprost eye drops were administered to 15 volunteers once daily for 8 days and 15 further volunteers received placebo eye drops according to the same protocol. IOP, blood pressure, heart rate, ocular pulse amplitudes, pulse volume, pulsatile ocular blood flow and contrast sensitivity were measured before (1T0), 120 min after drop administration (1T120), after 7 days of therapy (8T0) and again 120 min after an acute administration (8T120). For statistical analysis a two-way variance-analysis and the t-test for paired samples were used. RESULTS: IOP was found to be statistically significantly different comparing both groups over the test period (p = 0.036). In Latanoprost-treated subjects the t-test revealed a significant drop in IOP between 1T0 and 8T0 (p = 0.009) and between 1T0 and 8T120 (p < 0.0001). All other above mentioned parameters remained constant. CONCLUSION: In Latanoprost-treated subjects, a significant drop in intraocular pressure was observed after 1 week. However, ocular perfusion and contrast sensitivity did not change during therapy. This might be due to an effective autoregulation in healthy volunteers.

Standardized evaluation of long-term results after anterior lumbar interbody fusion.

A total of 113 patients, excluding those with tumor, spondylitis, and idiopathic scoliosis, underwent anterior lumbar interbody fusion (ALIF) with autologous iliac crest graft between 1984 and 1991 at our department. The proportion of these who were failed back patients was higher than that reported in the literature. Evaluation of functional outcome was feasible in 80 patients, utilizing Oswestry and Marburg scores, which were closely intercorrelated. The overall results yielded an improvement in the Oswestry score of 35.7 percentage points. A subset of 52 patients who were evaluated twice, showed the same results at an average of 6.6 years as they did at 2.3 years following surgery. Functional results showed a weak correlation with postoperative height loss of the intervertebral space. Influencing factors for the functional result were: postoperative compensation claim, age, and obesity. Of the professional people involved, 19.4% did not return to any occupation. Patients satisfied with the result had significantly greater functional improvement. Younger patients with additional dorsal distraction prior to ALIF for reduction of severe spondylolisthesis fared better than patients with ALIF alone. The rate of complications was low and did not contribute to the postoperative functional result. On the basis of these results further prospective studies have been designed and are currently underway.

Mechanism of amphotericin B resistance in Leishmania donovani promastigotes.

Amphotericin B (AmB)-resistant Leishmania donovani promastigotes were selected by increasing drug pressure, and their biological features were compared with those of the wild-type parent strain. The 50% inhibitory concentration for resistant cells was 20 times higher than that for the wild-type. Resistance was stable after more than 40 passages in drug-free medium, and resistant promastigotes were infective to macrophages in vitro but lost their virulence in vivo. They had 2.5 times longer generation time, decreased AmB uptake, and increased AmB efflux in comparison to the wild type. Fluorescence measurement with a specific plasma membrane probe, 1-[4-(trimethylammonio)-1,6-diphenylhexa]-1,3,5-triene, showed increased membrane fluidity in drug-resistant promastigotes. Analysis of lipid composition showed that in resistant cells saturated fatty acids were prevalent, with stearic acid as the major fatty acid, and the major sterol was an ergosterol precursor, the cholesta-5, 7, 24-trien-3beta-ol and not ergosterol as in the AmB-sensitive strain.