Small signal modulation of photonic crystal surface emitting lasers.

We report the small-signal characterization of a PCSEL device, extracting damping factors and modulation efficiencies, and demonstrating -3 dB modulation bandwidths of up to 4.26 GHz. Based on modelling we show that, by reducing the device width and improving the active region design for high-speed modulation, direct modulation frequencies in excess of 50 GHz are achievable.

Increased Production of Abdominal Donor Site Fluid Following Microsurgical Breast Reconstruction With Superficial Inferior Epigastric Artery Versus Deep Inferior Epigastric Artery Perforator Flaps.

Introduction and aims Donor site seroma following abdominal flap harvest for breast reconstruction is common in both deep inferior epigastric artery perforator (DIEP) and superficial inferior epigastric artery (SIEA) flaps. We tested the hypothesis that there is increased donor site fluid following SIEA dissection compared to DIEP. Materials and methods Of60 SIEA breast reconstructions performed by one surgeon in 50 patients (2004-2019), complete data were available for 31 patients. Eighteen unilateral SIEAs were matched with 18 unilateral DIEPs. Thirteen bilateral flap harvests involving an SIEA were matched with 13 bilateral DIEP controls. Their cumulative abdominal drain outputs, times to drain removal, hospital stay, and number and volume of seroma aspirations were compared. Results Patients who underwent an SIEA flap harvest had significantly increased drain output compared to only a DIEP flap harvest (SIEA=1,078 mL, DIEP=500 mL, p<0.001), which remained significant after controlling for confounding variables (p=0.002). There was increased time until drain removal (SIEA=11 days, DIEP=6 days, p=0.010), and patients who underwent an SIEA harvest were 14 times more likely to be discharged with a drain in situ (odds ratio (OR)=14.6, 95% confidence interval (CI)=2.8203-75.9565, p=0.0014). There was no significant difference in the number or volume of outpatient aspirations, length of hospital admission, or total seroma volume. Conclusion This study demonstrated that SIEA harvest is a significant predictor of increased abdominal drain output postoperatively. This accounted for longer periods before drain removal and more patients discharged with an abdominal drain in situ and should be an important consideration for reconstructive surgeons. There was no demonstrable difference in the number or volume of seroma aspirations after drain removal for either group.

The RecA-directed recombination pathway of natural transformation initiates at chromosomal replication forks in the pneumococcus.

Homologous recombination (HR) is a crucial mechanism of DNA strand exchange that promotes genetic repair and diversity in all kingdoms of life. Bacterial HR is driven by the universal recombinase RecA, assisted in the early steps by dedicated mediators that promote its polymerization on single-stranded DNA (ssDNA). In bacteria, natural transformation is a prominent HR-driven mechanism of horizontal gene transfer specifically dependent on the conserved DprA recombination mediator. Transformation involves internalization of exogenous DNA as ssDNA, followed by its integration into the chromosome by RecA-directed HR. How DprA-mediated RecA filamentation on transforming ssDNA is spatiotemporally coordinated with other cellular processes remains unknown. Here, we tracked the localization of fluorescent fusions to DprA and RecA in Streptococcus pneumoniae and revealed that both accumulate in an interdependent manner with internalized ssDNA at replication forks. In addition, dynamic RecA filaments were observed emanating from replication forks, even with heterologous transforming DNA, which probably represent chromosomal homology search. In conclusion, this unveiled interaction between HR transformation and replication machineries highlights an unprecedented role for replisomes as landing pads for chromosomal access of tDNA, which would define a pivotal early HR step for its chromosomal integration.

Excellent Survival and Good Outcomes at 15 Years Using the Press-Fit Condylar Sigma Total Knee Arthroplasty.

BACKGROUND: We report 15-year survival, clinical, and radiographic follow-up data for the Press-Fit Condylar Sigma total knee arthroplasty. METHODS: Between October 1998 and October 1999, 235 consecutive TKAs were performed in 203 patients. Patients were reviewed at a specialist nurse-led clinic before surgery and at 5, 8-10, and 15 years postoperatively. Clinical outcomes, including Knee Society Score, were recorded prospectively at each clinic visit, and radiographs were obtained. RESULTS: Of our initial cohort, 99 patients (118 knees) were alive at 15 years, and 31 patients (34 knees) were lost to follow-up. Thirteen knees (5.5%) were revised; 5 (2.1%) for infection, 7 (3%) for instability, and 1 (0.4%) for aseptic loosening. Cumulative survival with the end point of revision for any reason was 92.3% at 15 years and with revision for aseptic failure as the end point was 94.4%. The mean Knee Society Score knee score was 77.4 (33-99) at 15 years, compared with 31.7 (2-62) preoperatively. Of 71 surviving knees for which X-rays were available, 12 (16.9%) had radiolucent lines and 1 (1.4%) demonstrated clear radiographic evidence of loosening. CONCLUSION: The Press-Fit Condylar Sigma total knee arthroplasty represents a durable, effective option for patients undergoing knee arthroplasty, with excellent survival and good clinical and radiographic outcomes at 15 years.

Thermal injury induces impaired function in polymorphonuclear neutrophil granulocytes and reduced control of burn wound infection.

Severe thermal injury induces immunosuppression, involving all parts of the immune system, especially when large fractions of the total body surface area are affected. An animal model was established to characterize the burn-induced immunosuppression. In our novel mouse model a 6% third-degree burn injury was induced in mice with a hot-air blower. The third-degree burn was confirmed histologically. The mice were allocated into five groups: control, shave, burn, infection and burn infection group. At 48 h, a decline in the concentration of peripheral blood leucocytes was observed in the group of mice with burn wound. The reduction was ascribed to the decline in concentration of polymorphonuclear neutrophil leucocytes and monocytes. When infecting the skin with Pseudomonas aeruginosa, a dissemination of bacteria was observed only in the burn wound group. Histological characterization of the skin showed a more polymorphonuclear neutrophil granulocytes (PMNs)-dominated inflammation in the group of mice with infected burn wound compared with the with burn wound group. In contrast, a higher degree of inflammation was observed in the burn wound group compared with the group of mice with infected burn wound. Furthermore, the oxidative burst and the phagocytic capacity of the PMNs were reduced in the group of mice with burn wound. Using this novel mouse model of thermal injury a decline of peripheral leucocytes was observed, whereas the increased local inflammatory response at the site of infection showed reduced capacity to contain and eliminate the infection.

Presence of nonhemolytic pneumolysin in serotypes of Streptococcus pneumoniae associated with disease outbreaks.

Pneumolysin is an important virulence factor of the human pathogen Streptococcus pneumoniae. Sequence analysis of the ply gene from 121 clinical isolates of S. pneumoniae uncovered a number of alleles. Twenty-two strains were chosen for further analysis, and 14 protein alleles were discovered. Five of these had been reported previously, and the remaining 9 were novel. Cell lysates were used to determine the specific hemolytic activities of the pneumolysin proteins. Six strains showed no hemolytic activity, and the remaining 16 were hemolytic, to varying degrees. We report that the nonhemolytic allele reported previously in serotype 1, sequence type (ST) 306 isolates is also present in a number of pneumococcal isolates of serotype 8 that belong to the ST53 lineage. Serotype 1 and 8 pneumococci are known to be associated with outbreaks of invasive disease. The nonhemolytic pneumolysin allele is therefore associated with the dominant clones of outbreak-associated serotypes of S. pneumoniae.