Upper Gastrointestinal Involvement in Crohn's Disease as an Independent Predictor of New-Onset Strictures: Insights from an Extensive Retrospective Cohort Analysis.

BACKGROUND/AIMS: Crohn's Disease (CD) can affect the entire gastrointestinal tract, including the upper sections (UGI), which is often overlooked, especially in Asian populations. There's a notable gap in research regarding the impact of UGI involvement on the intricate landscape of ensuing complications. This study aims to address this gap. METHODS: Conducting a retrospective study at Chang Gung Memorial Hospital from January 2001 to September 2023, we compared CD patients with UGI (Montreal L4) involvement against non-L4 counterparts, focusing on baseline characteristics, post-diagnosis complications, and overall outcomes. Routine UGI endoscopy was performed around the time of diagnosis in all patients followed in our inflammatory bowel disease (IBD) center, and all CD patients with adequate follow-up were included in this study. RESULTS: The study included 212 CD patients, 111 in the L4 group and 101 in the non-L4 group, with an average follow-up of 40.8 ± 15.1 months. At baseline, individuals in the L4 category demonstrated elevated smoking rates, increased Crohn's Disease Activity Index scores, a higher prevalence of strictures, and a more prevalent usage of biologics and proton pump inhibitors. Moreover, this group was characterized by reduced albumin levels. Upon concluding the follow-up, those with L4 involvement continued to show escalated CDAI scores and hospitalization frequencies, alongside heightened C-reactive protein levels and diminished albumin concentrations. Additionally, the occurrence of UGI involvement, stricturing disease at the time of diagnosis, and a younger age at the onset of CD were pinpointed as independent predictors for the development of new-onset strictures. CONCLUSIONS: CD patients with UGI involvement exhibit elevated disease activity and serve as independent predictors for the development of intestinal strictures. Thorough UGI evaluations at the time of diagnosis, coupled with assertive treatment strategies, are essential for managing these patients effectively.

Impact of completely histological remission on reducing flare-ups in moderate-to-severe, biologics-experienced ulcerative colitis patients with endoscopic remission.

BACKGROUND/PURPOSE: Endoscopic remission is presently recognized as the standard therapeutic target in the treatment of ulcerative colitis (UC). However, achieving histological remission is increasingly viewed as a pivotal objective. This study investigates the effects of attaining completely histological remission on the clinical outcomes for UC patients with a high disease burden who have already reached endoscopic remission. This is the inaugural study to concentrate on this specific patient demographic. METHODS: This retrospective cohort study enrolled moderate-to-severe, biologics-experienced UC patients with completely endoscopic remission (Mayo endoscopic subscore of 0) between June 2017 and October 2023 at Chang Gung Memorial Hospital, Linkou. Patients were classified into histological remission (HR) and non-histological remission (non-HR) groups based on the Nancy index (NI). HR was defined as an NI score of 0, with all other patients categorized as non-HR. The definition of flare-ups was based on both clinical and endoscopic evidence. Comparative analyses focused on baseline characteristics and clinical outcomes at follow-up. RESULTS: A total of 42 patients (HR group: 23, non-HR group: 19) were included. The average follow-up duration was 17.6 months. Baseline characteristics were comparable between the groups. At the end of follow-up, the HR group showed a significantly lower rate of acute flare-ups (26.1% vs. 68.4%, P = 0.006). Although not statistically significant, the HR group also experienced fewer emergency department visits and hospital admissions. CONCLUSIONS: For moderate-to-severe, biologics-experienced UC patients in endoscopic remission, achieving completely histological remission is associated with a substantial reduction in flare-ups, suggesting its potential as a valuable therapeutic target.

Development and validation of a Chinese version chronic wound health-related quality of life instrument: A methodological study.

AIMS AND OBJECTIVES: To develop a Chinese version of a chronic wound health-related quality of life (QoL) instrument and to examine the psychometric properties of this instrument. BACKGROUND: Existing QoL instruments are not tailored to the linguistic and cultural characteristics of Chinese-speaking patients; a version addressing this gap will increase clinical understanding of their healthcare experience and may help guide chronic wound care. DESIGN: A methodological study. METHODS: The method advanced by DeVellis (2017) was used to develop the instrument. An initial pool of 38 items was created. To optimize scale length and test reliability and validity, exploratory and confirmatory factor analyses were conducted. A total of 23 items formed the final pool. After two rounds of expert discussions, the average content validity index of the final 23 items was .89. RESULTS: A total of 226 patients completed the instrument and were divided into two groups for further analysis. Exploratory factor analysis revealed that 15 items remained in four factors (social activity restrictions, physical and psychological disturbance, wound burden and daily life limitation), which accounted for 64.87% of the variance. Confirmatory factor analysis revealed an acceptable fit of the hypothesized factor structure and the convergent and discriminant validities were achieved. Cronbach's α coefficients for each factor were .807, .773, .799 and .713, respectively. CONCLUSION: The Chinese version of a chronic wound health-related QoL instrument consists of 15 items in four subscales and demonstrates good reliability and validity. RELEVANCE TO CLINICAL PRACTICE: This instrument can be used intermittently or continuously to evaluate the treatment effect of chronic wounds by assessing health-related QoL. Scholars in Chinese-speaking regions may find this culturally compatible instrument useful when conducting studies related to chronic wounds. PATIENT OR PUBLIC CONTRIBUTION: Two hundred twenty-six participants provided their perspectives on health-related QoL.

Enabling Secure Communication in Wireless Body Area Networks with Heterogeneous Authentication Scheme.

Thanks to the widespread availability of Fifth Generation (5G) wireless connectivity, it is now possible to provide preventative or proactive healthcare services from any location and at any time. As a result of this technological improvement, Wireless Body Area Networks (WBANs) have emerged as a new study of research in the field of healthcare in recent years. WBANs, on the one hand, intend to gather and monitor data from the human body and its surroundings; on the other hand, biomedical devices and sensors interact through an open wireless channel, making them exposed to a range of cyber threats. However, WBANs are a heterogeneous-based system; heterogeneous cryptography is necessary, in which the transmitter and receiver can employ different types of public key cryptography. This article proposes an improved and efficient heterogeneous authentication scheme with a conditional privacy-preserving strategy that provides secure communication in WBANs. In the proposed scheme, we employed certificateless cryptography on the client side and Identity-Based Cryptography on the receiver side. The proposed scheme employs Hyperelliptic Curve Cryptography (HECC), a more advanced variation of Elliptic Curve Cryptography (ECC). HECC achieves the same level of security with a smaller key size and a more efficient approach than its counterpart methods. The proposed scheme not only meets the security and privacy standards of WBANs but also enhances efficiency in terms of computation and communication costs, according to the findings of the security and performance analysis.

LAP-IoHT: A Lightweight Authentication Protocol for the Internet of Health Things.

The Internet of Health Things (IoHT), which is an extension of the Internet of Things (IoT) in healthcare, has provided a new type of telemedicine approach. In IoHT, wearable sensors are used to collect patient health data, and information is transmitted remotely to doctors who can develop accurate treatment plans and provide timely telemedicine services to patients. However, patient health data are transmitted over a public channel, which means that the privacy and medical data of patients are at significant risk of leakage and can be confronted by serious security problems. We proposed a lightweight authentication protocol known as LAP-IoHT for IoHT environments to overcome the various threats that are currently faced by IoHT. We verified the security of LAP-IoHT using a Real-or-Random model and demonstrated its significant performance advantage by conducting a comparative analysis with other similar protocols for a better adaptation to the IoHT environment.

Predicting Healthy C5 Spinal Nerve Stumps Eligible for Grafting with MRI, Tinel Test, and Rhomboid Electromyography: A Retrospective Study of 295 Consecutive Brachial Plexus Surgeries.

Background MRI, Tinel test, and rhomboid electromyography (EMG) can be used to predict whether C5 spinal nerve stumps are healthy and eligible for grafting in acute adult brachial plexus injuries, but their comparative diagnostic efficacies have not been evaluated. Purpose To compare diagnostic performances of MRI, Tinel test, and rhomboid EMG in predicting healthy C5 spinal nerve stumps that are eligible for grafting. Materials and Methods This retrospective study included consecutive adult patients with acute brachial plexus injury who underwent microreconstructions between January 2008 and December 2018. Healthy C5 spinal nerve stumps eligible for grafting with preceding normal intradural nerve rootlets were diagnosed by an experienced neuroradiologist using an avulsion severity score system based on fast imaging employing steady-state acquisition or FIESTA neurography, which separates intradural nerve rootlets into normal, partial mild, severe, and complete avulsions. Tinel test and rhomboid EMG results were assessed by an experienced nerve surgeon and neurologist, respectively. The accuracy, sensitivity, and specificity of the three tests were compared using microdissection as the reference standard. P < .05 was considered to indicate a significant difference. Results A total of 251 patients (mean age, 31 years ± 13 [standard deviation]; 217 men) with brachial plexus injuries who had -undergone MRI (n = 251), Tinel test (n = 235), rhomboid EMG (n = 181) and MRI, Tinel test, and EMG (n = 172) were -included. Accuracy, sensitivity, and specificity, respectively, in predicting healthy C5 spinal nerve stumps eligible for grafting were 93% (233 of 251), 84% (58 of 69), and 96% (175 of 182) for MRI; 59% (139 of 235), 56% (37 of 66), and 60% (102 of 169) for Tinel test; and 39% (71 of 181), 85% (43 of 50), and 21% (28 of 131) for rhomboid EMG. MRI (area under the receiver operating characteristic curve [AUC], 0.90; P < .001) -outperformed MRI and Tinel test (AUC, 0.74), Tinel test (AUC, 0.59), and rhomboid EMG (AUC, 0.53). Conclusion MRI performed best in the prediction of healthy graftable C5 spinal nerve stumps in acute adult brachial plexus injuries. © RSNA, 2021 Online supplemental material is available for this article.

Outpatient Percutaneous Endovascular Abdominal Aortic Aneurysm Repair: A Single-Center Experience.

PURPOSE: To evaluate the safety of outpatient percutaneous endovascular abdominal aortic repair (PEVAR) versus inpatient PEVAR without or with adjunct procedures. MATERIALS AND METHODS: Between January 2012 and June 2019, a cohort of 359 patients comprising 168 (46.8%) outpatients and 191 (53.2%) inpatients who had undergone PEVAR were enrolled. All the patients were asymptomatic but had indications for endovascular aortic repair, ie, fit for intravenous anesthesia and anatomically feasible with standard devices. Patient sex, age, comorbidities, smoking status, type of anesthesia, adjunct procedures, type of graft device, operative times, mortality, complications, and readmissions were analyzed. RESULTS: Median follow-up period was 16.5 months (interquartile range, 9-31 months). Except for a higher percentage of tobacco use (42.6% vs 28.8%; P = .04), dyslipidemia (39.7% vs 19.2%; P < .01), and use of local anesthesia (99.4% vs 82.2%; P < .01) in the outpatients, there was no significant difference in the type of graft and adjunct procedures used. No outpatient mortality occurred. There was no difference in the number, severity, and onset of complications (all P > .05). Outpatient unexpected same-day admission, 30-day readmission, and emergency department visit rates were 4.8%, 2.4% (P = .13), and 10% (P < .01), respectively. Operative times for outpatient PEVAR without adjunct procedures were shorter (P < .01). CONCLUSIONS: Outpatient PEVAR can be performed with a safety profile similar to that of inpatient PEVAR. The unexpected same-day admission, 30-day readmission, and emergency department visit rates were low. The outpatient PEVARs without adjunct procedures took less time.

Vedolizumab combined with surgical resection successfully treated perforating Crohn's disease with peritoneal space to rectal and vaginal fistulas: a case report.

BACKGROUND: Intestinal perforations and fistulas are common complications of Crohn's disease. However, chronic perforation with peritoneal space to rectal and vaginal fistulas have not been previously reported. CASE PRESENTATION: A 38-year-old female suffered from progressive lower abdominal pain, diarrhea and weight loss. Terminal ileal chronic perforation with intra-abdominal abscess, peritoneal space to rectal and vaginal fistulas were noted. The patient received surgical resection of the cecum and terminal ileum, and then vedolizumab treatment. Three months later, she had complete fistula closure, and her body mass index had increased from 13 to 22. CONCLUSION: Vedolizumab combined with stool diversion is effective at treating Crohn's disease with chronic perforation and complex peritoneal space to rectal and vaginal fistulas.

Response Findings after Treatment and Outcomes on CT after Endovascular Repair of Mycotic Aortic Aneurysm.

PURPOSE: To demonstrate post-treatment computed tomography (CT) findings and outcomes of endovascular aortic repair (EVAR) for mycotic aortic aneurysm (MAA). MATERIALS AND METHODS: Clinical data of patients with MAA who underwent EVAR from June 2010 to December 2017 were retrospectively reviewed. A total of 22 patients were included (19 men and 3 women). The periaortic features of the MAA regression after EVAR were graded and evaluated by follow-up CT. RESULTS: The median follow-up was 36.5 months (range, 0.5-97 months.). The cumulative survival rate at 1 month, 6 months, 1 year, and 5 years was 95.5%, 86.4%, 81.6%, and 73.4%, respectively. The early and late infection-related complication (IRC) rate was 18.2% and 13.6%, respectively. One patient died within 1 month from severe acidosis and shock. Of the other patients, the median time to stable response of the MAA was 6 months (range, 3-36 months). Fourteen patients (66.7%) showed early response of the MAA, while 7 patients (33.3%) showed delayed response. A significant association was observed between delayed response and late IRCs (P = .026). CONCLUSIONS: The post-EVAR periaortic features on follow-up CT aid in monitoring the treatment response of the MAA. Early response of the MAA was associated with a low rate of late IRCs and might aid in adjusting the antibiotic duration after the patient has achieved complete or nearly complete regression of the MAA.

Use of the Octopus Technique for Endovascular Treatment of Complex Aortic Lesions.

PURPOSE: To evaluate feasibility and effectiveness using the octopus endograft technique to treat complex aortic aneurysms (CAAs). MATERIALS AND METHODS: Endovascular repair of CAAs, including thoracoabdominal aneurysms (TAAAs) and dissections involving major side branches, was performed at a single center from June 2014 to June 2017. Patients included 9 men and 2 women (mean age, 60.5 y; range, 40-89 y) were included. The octopus technique was applied using standard aortic grafts with branch stent grafts to preserve the renovisceral arteries. RESULTS: Aortic pathologies comprised 3 mycotic aneurysms, 2 chronic dissections with acute rupture, 1 progressively enlarging chronic type B dissection, 1 acutely ruptured TAAA, and 4 unruptured TAAAs. Mean procedural and fluoroscopic times were 562 min (range, 324-840 min) and 183 min (range, 73-338 min), respectively. Three patients died within 1 month. Mean duration of follow-up was 26.3 months (range, 8-42 months) for remaining patients. Technical success rate of target vessel stent placement was 89.7% (35/39). Major complication rate was 45.5% (5/11), including 3 deaths, 1 permanent paraplegia, and 1 temporary paraplegia that resolved in 2 months. All 3 mycotic aneurysms with mean duration of follow-up of 29 months (range, 8-42 months) were excluded successfully without endoleak. CONCLUSIONS: The octopus technique is feasible for treatment of CAAs requiring urgent management or with difficult anatomy without the use of available custom-made or off-the-shelf branched devices. The procedure carries substantial morbidity and mortality and requires further investigation for its long-term durability.

Cryptanalysis and Improvement of a Privacy-Preserving Three-Factor Authentication Protocol for Wireless Sensor Networks.

Wireless sensor networks (WSNs) are of prominent use in unmanned surveillance applications. This peculiar trait of WSNs is actually the underlying technology of various applications of the Internet of Things (IoT) such as smart homes, smart cities, smart shopping complexes, smart traffic, smart health, and much more. Over time, WSNs have evolved as a strong base for laying the foundations of IoT infrastructure. In order to address the scenario in which a user wants to access the real-time data directly from the sensor node in wireless sensor networks (WSNs), Das recently proposed an anonymity-preserving three-factor authentication protocol. Das's protocol is suitable for resource-constrained sensor nodes because it only uses lightweight cryptographic primitives such as hash functions and symmetric encryption schemes as building blocks. Das's protocol is claimed to be secure against different known attacks by providing formal security proof and security verification using the Automated Validation of Internet Security Protocols and Applications tool. However, we find that Das's protocol has the following security loopholes: (1) By using a captured sensor node, an adversary can impersonate a legal user to the gateway node, impersonate other sensor nodes to deceive the user, and the adversary can also decrypt all the cipher-texts of the user; (2) the gateway node has a heavy computational cost due to user anonymity and thus the protocol is vulnerable to denial of service (DoS) attacks. We overcome the shortcomings of Das's protocol and propose an improved protocol. We also prove the security of the proposed protocol in the random oracle model. Compared with the other related protocols, the improved protocol enjoys better functionality without much enhancement in the computation and communication costs. Consequently, it is more suitable for applications in WSNs.

Local hemostatic matrix for endoscope-assisted removal of intracerebral hemorrhage is safe and effective.

BACKGROUND/PURPOSE: Minimally invasive endoscope-assisted (MIE) evacuation of spontaneous intracerebral hemorrhage (ICH) is simple and effective, but the limited working space may hinder meticulous hemostasis and might lead to rebleeding. Management of intraoperative hemorrhage is therefore a critical issue of this study. This study presents experience in the treatment of patients with various types of ICH by MIE evacuation followed by direct local injection of FloSeal Hemostatic Matrix (Baxter Healthcare Corp, Fremont, CA, USA) for hemostasis. METHODS: The retrospective nonrandomized clinical and radiology-based analysis enrolled 42 patients treated with MIE evacuation of ICH followed by direct local injection of FloSeal Hemostatic Matrix. Rebleeding, morbidity, and mortality were the primary endpoints. The percentage of hematoma evacuated was calculated from the pre- and postoperative brain computed tomography (CT) scans. Extended Glasgow Outcome Scale (GOSE) was evaluated at 6 months postoperatively. RESULTS: Forty-two ICH patients were included in this study, among these, 23 patients were putaminal hemorrhage, 16 were thalamic ICH, and the other three were subcortical type. Surgery-related mortality was 2.4%. The average percentage of hematoma evacuated was 80.8%, and the rebleeding rate was 4.8%. The mean operative time was 102.7 minutes and the average blood loss was 84.9 mL. The mean postoperative GOSE score was 4.55 at 6-months' follow-up. CONCLUSION: This study shows that local application of FloSeal Hemostatic Matrix is safe and effective for hemostasis during MIE evacuation of ICH. In our experience, this shortens the operation time, especially in cases with intraoperative bleeding. A large, prospective, randomized trial is needed to confirm the findings.

Complete chloroplast genome of Gracilaria firma (Gracilariaceae, Rhodophyta), with discussion on the use of chloroplast phylogenomics in the subclass Rhodymeniophycidae.

BACKGROUND: The chloroplast genome of Gracilaria firma was sequenced in view of its role as an economically important marine crop with wide industrial applications. To date, there are only 15 chloroplast genomes published for the Florideophyceae. Apart from presenting the complete chloroplast genome of G. firma, this study also assessed the utility of genome-scale data to address the phylogenetic relationships within the subclass Rhodymeniophycidae. The synteny and genome structure of the chloroplast genomes across the taxa of Eurhodophytina was also examined. RESULTS: The chloroplast genome of Gracilaria firma maps as a circular molecule of 187,001 bp and contains 252 genes, which are distributed on both strands and consist of 35 RNA genes (3 rRNAs, 30 tRNAs, tmRNA and a ribonuclease P RNA component) and 217 protein-coding genes, including the unidentified open reading frames. The chloroplast genome of G. firma is by far the largest reported for Gracilariaceae, featuring a unique intergenic region of about 7000 bp with discontinuous vestiges of red algal plasmid DNA sequences interspersed between the nblA and cpeB genes. This chloroplast genome shows similar gene content and order to other Florideophycean taxa. Phylogenomic analyses based on the concatenated amino acid sequences of 146 protein-coding genes confirmed the monophyly of the classes Bangiophyceae and Florideophyceae with full nodal support. Relationships within the subclass Rhodymeniophycidae in Florideophyceae received moderate to strong nodal support, and the monotypic family of Gracilariales were resolved with maximum support. CONCLUSIONS: Chloroplast genomes hold substantial information that can be tapped for resolving the phylogenetic relationships of difficult regions in the Rhodymeniophycidae, which are perceived to have experienced rapid radiation and thus received low nodal support, as exemplified in this study. The present study shows that chloroplast genome of G. firma could serve as a key link to the full resolution of Gracilaria sensu lato complex and recognition of Hydropuntia as a genus distinct from Gracilaria sensu stricto.

Predictive Factors for Additional ProGlide Deployment in Percutaneous Endovascular Aortic Repair.

PURPOSE: To evaluate outcomes and predictive factors for additional ProGlide device deployment in percutaneous endovascular aortic repair (PEVAR) with the preclose technique. MATERIALS AND METHODS: Clinical data of patients who underwent PEVAR with the preclose technique from February 2012 to January 2015 were retrospectively reviewed. A total of 268 patients (229 men, 39 women) who underwent PEVAR (thoracic endovascular aortic repair [TEVAR], n = 113; endovascular abdominal aortic repair [EVAR], n = 152; simultaneous TEVAR and EVAR, n = 3) with 418 femoral access sites were enrolled. The mean age of the patients was 69 years ± 14. Univariate and multivariate analyses were performed to identify predictive factors associated with additional ProGlide device deployment. RESULTS: Primary technical success with adequate hemostasis and two ProGlide devices was 87.6%, and 48 femoral arterial access sites (11.5%) required additional ProGlide device deployment. The secondary technical success rate was 99.0%. Four femoral access sites (1.0%) needed surgical repair. Anterior wall calcification near the arteriotomy increased the risk of additional ProGlide device deployment (adjusted odds ratio, 6.19; 95% confidence interval, 2.81-13.64; P < .001), whereas larger sheath size, common femoral artery (CFA) diameter, and depth from the skin to the arteriotomy did not. CONCLUSIONS: Additional ProGlide device deployment reduces the rate of surgical repair after primary hemostasis failure in PEVAR. Anterior CFA wall calcification is a significant predictor for additional ProGlide device deployment.

Accumulation of methylglyoxal and d-lactate in Pb-induced nephrotoxicity in rats.

Lead (Pb) is an environmental pollutant associated with several diseases, such as nephrotoxicity. Methylglyoxal (MG) is a reactive dicarbonyl compound formed during glycolysis and reported to increase in kidney damage. Metformin is used as an MG scavenger in the clinic. In this study, we investigated the mechanism of Pb-induced renal injury and the effect of metformin on Pb-induced nephrotoxicity. Eighteen Wistar rats were randomly divided into three groups: control, Pb, and Pb + metformin groups. Pb (250 ppm) was administered in drinking water, and 50 mg/kg of metformin was co-administered orally. After 28 days, the levels of MG and its metabolite d-lactate in urine, serum and renal tissues were examined. The elevation of renal MG (56.86 ± 17.47 vs 36.40 ± 5.69, p < 0.01) and urinary d-lactate (0.68 ± 0.28 vs 0.32 ± 0.13, p < 0.01) was observed in Pb-exposed rats compared with those in control rats. After co-treatment with metformin, these phenomena were attenuated. In the present study, it was demonstrated for the first time that urinary d-lactate might serve as the candidate marker for Pb-induced nephrotoxicity in the clinic, and metformin might be a new therapeutic candidate for Pb poisoning.

An Efficient User Authentication and User Anonymity Scheme with Provably Security for IoT-Based Medical Care System.

In recent years, with the increase in degenerative diseases and the aging population in advanced countries, demands for medical care of older or solitary people have increased continually in hospitals and healthcare institutions. Applying wireless sensor networks for the IoT-based telemedicine system enables doctors, caregivers or families to monitor patients' physiological conditions at anytime and anyplace according to the acquired information. However, transmitting physiological data through the Internet concerns the personal privacy of patients. Therefore, before users can access medical care services in IoT-based medical care system, they must be authenticated. Typically, user authentication and data encryption are most critical for securing network communications over a public channel between two or more participants. In 2016, Liu and Chung proposed a bilinear pairing-based password authentication scheme for wireless healthcare sensor networks. They claimed their authentication scheme cannot only secure sensor data transmission, but also resist various well-known security attacks. In this paper, we demonstrate that Liu-Chung's scheme has some security weaknesses, and we further present an improved secure authentication and data encryption scheme for the IoT-based medical care system, which can provide user anonymity and prevent the security threats of replay and password/sensed data disclosure attacks. Moreover, we modify the authentication process to reduce redundancy in protocol design, and the proposed scheme is more efficient in performance compared with previous related schemes. Finally, the proposed scheme is provably secure in the random oracle model under ECDHP.

Passively Q-switched Er3+-doped fiber lasers using colloidal PbS quantum dot saturable absorber.

We report on the demonstration of a passively Q-switched 1.55 µm fiber laser utilizing a colloidal PbS quantum dot (QD) thin film as a saturable absorber. Colloidal PbS QD films have several features that are advantageous in passively Q-switched fiber laser operation, including a large operation wavelength range, cost-effectiveness, and a low saturable absorption intensity. We conducted thorough material and optical studies to verify the advantages of PbS QDs in Q-switched laser operation and successfully generated 801 nJ pulses with a 24.2 kHz repetition rate. To the best of our knowledge, the developed Q-switched fiber laser is the first based on colloidal PbS QDs.

Ecological genomics in Xanthomonas: the nature of genetic adaptation with homologous recombination and host shifts.

BACKGROUND: Comparative genomics provides insights into the diversification of bacterial species. Bacterial speciation usually takes place with lasting homologous recombination, which not only acts as a cohering force between diverging lineages but brings advantageous alleles favored by natural selection, and results in ecologically distinct species, e.g., frequent host shift in Xanthomonas pathogenic to various plants. RESULTS: Using whole-genome sequences, we examined the genetic divergence in Xanthomonas campestris that infected Brassicaceae, and X. citri, pathogenic to a wider host range. Genetic differentiation between two incipient races of X. citri pv. mangiferaeindicae was attributable to a DNA fragment introduced by phages. In contrast to most portions of the genome that had nearly equivalent levels of genetic divergence between subspecies as a result of the accumulation of point mutations, 10% of the core genome involving with homologous recombination contributed to the diversification in Xanthomonas, as revealed by the correlation between homologous recombination and genomic divergence. Interestingly, 179 genes were under positive selection; 98 (54.7%) of these genes were involved in homologous recombination, indicating that foreign genetic fragments may have caused the adaptive diversification, especially in lineages with nutritional transitions. Homologous recombination may have provided genetic materials for the natural selection, and host shifts likely triggered ecological adaptation in Xanthomonas. To a certain extent, we observed positive selection nevertheless contributed to ecological divergence beyond host shifting. CONCLUSION: Altogether, mediated with lasting gene flow, species formation in Xanthomonas was likely governed by natural selection that played a key role in helping the deviating populations to explore novel niches (hosts) or respond to environmental cues, subsequently triggering species diversification.