MonteCat: A Basin-Hopping-Inspired Catalyst Descriptor Search Algorithm for Machine Learning Models.

Proposing relevant catalyst descriptors that can relate the information on a catalyst's composition to its actual performance is an ongoing area in catalyst informatics, as it is a necessary step to improve our understanding on the target reactions. Herein, a small descriptor-engineered data set containing 3289 descriptor variables and the performance of 200 catalysts for the oxidative coupling of methane (OCM) is analyzed, and a descriptor search algorithm based on the workflow of the Basin-hopping optimization methodology is proposed to select the descriptors that better fit a predictive model. The algorithm, which can be considered wrapper in nature, consists of the successive generation of random-based modifications to the descriptor subset used in a regression model and adopting them depending on their effect on the model's score. The results are presented after being tested on linear and Support Vector Regression models with average cross-validation r2 scores of 0.8268 and 0.6875, respectively.

Embolization for pediatric trauma.

BACKGROUND: The management of pediatric trauma with trans-arterial embolization is uncommon, even in level 1 trauma centers; hence, there is a dearth of literature on this subject compared to the adult experience. OBJECTIVE: To describe a single-center, level 1 trauma center experience with arterial embolization for pediatric trauma. MATERIALS AND METHODS: A retrospective review was performed to identify demographics, transfusion requirements, pre-procedure imaging, procedural details, adverse events, and arterial embolization outcomes over a 19-year period. Twenty children (age 4.5 months to 17 years, median 13.5 years; weight 3.6 to 108 kg, median 53 kg) were included. Technical success was defined as angiographic resolution of the bleeding-related abnormality on post-embolization angiography or successful empiric embolization in the absence of an angiographic finding. Clinical success was defined as not requiring additional intervention after embolization. RESULTS: Seventy-five percent (n=15/20) of patients required red blood cell transfusions prior to embolization with a mean volume replacement 64 ml/kg (range 12-166 ml/kg) and the median time from injury to intervention was 3 days (range 0-16 days). Technical success was achieved in 100% (20/20) of children while clinical success was achieved in 80% (n=16/20). For the 4 children (20%) with continued bleeding following initial embolization, 2 underwent repeat embolization, 1 underwent surgery, and 1 underwent repeat embolization and surgery. Mortality prior to discharge was 15% (n=3). A post-embolization mild adverse event included one groin hematoma, while a severe adverse event included one common iliac artery pseudoaneurysm requiring open surgical ligation. CONCLUSIONS: In this single-center experience, arterial embolization for hemorrhage control in children after trauma is feasible but can be challenging and the clinical failure rate of 20% in this series reflects this complexity. Standardization of pre-embolization trauma assessment parameters and embolic techniques may improve outcomes.

Characterization and treatment of thoracic duct obstruction in patients with lymphatic flow disorders.

PURPOSE: The contribution of thoracic duct obstruction to lymphatic flow disorders has not been well-characterized. We describe imaging findings, interventions, and outcomes in patients with suspected duct obstruction by imaging or a lympho-venous pressure gradient (LVPG). MATERIALS AND METHODS: Clinical, imaging, and interventional data, including the LVPG, of patients with flow disorders and imaging features of duct obstruction who underwent lymphatic intervention were retrospectively reviewed, collated, and analyzed with descriptive statistics. RESULTS: Eleven patients were found to have obstruction, median age 10.4 years (interquartile range: 8-14.9 years). Pleural effusions were seen in 8/11 (72%), ascites in 8/11 (72%), both in 5/11 (45%), and protein-losing enteropathy in 5 (45%). Eight patients (72%) had congenital heart disease. The most common site of obstruction was at the duct outlet in 7/11 patients (64%). Obstruction was secondary to extrinsic compression or ligation 4 patients (36%). Nine patients (82%) underwent interventions, with balloon dilation in 7/9 (78%), massive lymphatic malformation drainage and sclerotherapy in 1, and lympho-venous anastomosis in 1. There was resolution of symptoms in 7/9 (78% who underwent intervention, with worsening in 1 patient and no change in 1. In these patients, preprocedure mean LVPG was 7.9 ± 5.7 mmHg and postprocedure gradient was 1.6 ± 1.9 mmHg (p = 0.014). Five patients in this series underwent intervention solely to alleviate duct obstruction and in 4/5 (80%) this led to resolution of symptoms (p = 0.05). CONCLUSION: Duct obstruction may be seen in lymphatic flow disorders and can occur from intrinsic and extrinsic causes. Stenosis at the outlet was most common. Obstruction can be demonstrated by an elevated LVPG, and interventions to alleviate the obstruction can be beneficial.

Percutaneous Nephrostomy in Neonates and Young Infants.

PURPOSE: To describe a single-center experience of placing percutaneous nephrostomy (PCN) tubes in neonates and young infants aged ≤3 months. MATERIALS AND METHODS: This retrospective study evaluated PCN placement during a 19-year period. Medical records were reviewed for patient demographics, indications, procedure details, catheter-related adverse events, and outcomes. A total of 45 primary PCN insertions were attempted in 29 children (median age, 11 days [range, first day of life to 3 months]; median weight, 3.5 kg [range, 1.4-7.0 kg]). Salvage procedures resulted in 13 secondary catheters in 6 children. The most common indication was ureteropelvic junction obstruction (40.0%), and the most common urinary tract dilation classification was P3 (88.9%). RESULTS: Technical success for primary placements was 95.6%; both technical failures were due to loss of access in the same patient. Of primary placements, 76.7% were electively removed, 6.9% were dislodged but not replaced, and the remaining 16.3% required salvage procedures. Mechanical adverse events occurred in 20.9% of primary and 53.8% of secondary catheters, including partial retraction, complete dislodgement, and occlusion. Urinary tract infections (UTIs) occurred in 18.6% of primary and 15.4% of secondary catheters. Urosepsis occurred in 2.3% of primary and 7.7% of secondary catheters. Median primary catheter dwell time was 41 days (range, 1-182 days) and median secondary catheter dwell time was 31 days (range, 10-107 days). CONCLUSION: PCN placement in neonates and young infants has a high technical success rate, although not without particular procedural and management challenges of catheter malfunction and UTI.

In utero torsion of an accessory hepatic lobe mimicking a congenital tumor.

Accessory hepatic lobes are rare anatomic variants connected to the liver by a fibrous stalk or parenchymal attachments. They are usually detected incidentally, but torsion is a rare complication. Here, we report torsion of an accessory hepatic lobe occurring in utero with a focus on the MRI findings. The lesion mimicked a congenital tumor, and we provide potential clues that may have narrowed the differential diagnosis prior to surgical exploration.

Adjunctive techniques for percutaneous enteral access in children: a pictorial review.

Primary percutaneous gastrostomy and gastrojejunostomy tube placements are fundamental procedures performed in pediatric interventional radiology, with both antegrade and retrograde techniques described. In pediatric patients, however, challenges may arise due to smaller patient size and anatomical variations. Several adjunctive techniques may facilitate safe percutaneous access in the setting of a limited percutaneous gastric access window. These include the intra-procedural use of cone beam computed tomography (CT), percutaneous needle decompression in the setting of distended air-filled bowel interposed between the stomach and abdominal wall, post-pyloric balloon occlusion to facilitate gastric distension, ultrasound-guided gastric puncture, and intra-gastric contrast-enhanced ultrasound (ceUS) to define the relationship of the gastric wall and the anterior abdominal wall. Adjunctive techniques may increase successful primary percutaneous gastroenteric tube placement and may improve operator confidence in safe placement.

State-of-the-art imaging for lymphatic evaluation in children.

The lymphatic system has been poorly understood and its importance neglected for decades. Growing understanding of lymphatic flow pathophysiology through peripheral and central lymphatic flow imaging has improved diagnosis and treatment options in children with lymphatic diseases. Flow dynamics can now be visualized by different means including dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL), the current standard technique to depict central lymphatics. Novel imaging modalities including intranodal, intrahepatic and intramesenteric DCMRL are quickly evolving and have shown important advances in the understanding and guidance of interventional procedures in children with intestinal lymphatic leaks. Lymphatic imaging is gaining importance in the radiologic and clinical fields and new techniques are emerging to overcome its limitations.

Dynamic contrast-enhanced MR lymphangiography: feasibility of using ferumoxytol in patients with chronic kidney disease.

PURPOSE: To assess the feasibility of direct intra-lymphatic administration of diluted ferumoxytol as a T1-positive contrast agent for dynamic contrast-enhanced MR lymphangiography (DCMRL) imaging of the central lymphatics in children with renal disease. METHODS: In vitro scan of dilute ferumoxytol was initially performed using time-resolved and high-resolution 3D gradient echo (GRE) sequences with short TE values (1 to 1.5 ms). A ferumoxytol concentration of 0.25 to 0.40 mg/mL was found to retain high signal in the T1-weighted sequences. DCMRL was then performed in 4 children with renal disease with the same 3D GRE sequences administrating diluted ferumoxytol via intra-mesenteric (IM), intra-hepatic (IH), and intra-nodal (IN) routes (6 to 9 mL to each site; average total dose of 0.75 mg/kg) by slow hand injection (0.5 to 1.0 mL/min). The signal-to-noise ratio (SNR) of the lymphatics was measured for quantitative evaluation. RESULTS: Ferumoxytol-enhanced DCMRL was technically successful in all patients. Contrast conspicuity within the lymphatics was sufficient without subtraction. The mean SNR was significantly higher than the muscle (50.1 ± 12.2 vs 13.2 ± 2.8; t = 15.9; p < .001). There were no short-term complications attributed to the administration of ferumoxytol in any of the four patients. CONCLUSION: Magnetic resonance lymphangiography using ferumoxytol via IN, IH, and IM access is a new method to directly visualize the central lymphatic system and can be applied safely in patients with renal failure based on our preliminary report of four cases. Ferumoxytol-enhanced DCMRL shows diagnostic image quality by using 3D GRE sequences with short TE values and appropriate dilution of ferumoxytol. KEY POINTS: • MR lymphangiography using ferumoxytol via intra-nodal, intra-hepatic, and intra-mesenteric access is a new method to directly visualize the central lymphatic system from the groin to the venous angle. • FDCMRL can be applied safely in patients with renal failure based on our preliminary report of four cases. • FDCMRL shows diagnostic image quality by using 3D GRE sequences with short TE values and appropriate dilution of the ferumoxytol.

Liver lymphatic anatomy and role in systemic lymphatic disease.

OBJECTIVES: To characterize hepatic to systemic lymphatic connections in patients with systemic lymphatic disease using intra-hepatic lymphangiography and to compare outcomes after lymphatic intervention. METHODS: In this retrospective study, patients with intra-hepatic lymphangiography from May 2014 - April 2019 at our institution were included. Imaging review was performed and hepatic lymphatic connections and flow patterns were characterized. Clinical data were reviewed and comparisons between patients undergoing lymphatic intervention with or without abnormal hepatic lymphatics were performed. RESULTS: During the study period, 105 patients underwent intra-hepatic lymphangiography. Primary clinical presentation included ascites (19/105), chylothorax (27/105), plastic bronchitis (PB) (17/105), and protein losing enteropathy (PLE) (42/105). Five categories of hepatic lymphatic connections and flow patterns were identified (%): normal (25%, 26/105), hepatoperitoneal (12%, 13/105), hepatopulmonary (10.5%, 11/105), hepatomesenteric (7.5%, 8/105), and hepatoduodenal (41%, 43/105) with four patients having more than one abnormal pattern. A comparison between clinical presentation and imaging category revealed an increased likelihood of having ascites with hepatoperitoneal (p < .0001), chylothorax/PB with hepatopulmonary (p = .01), and PLE with hepatoduodenal (p < .001) connections. Seventy-six patients had a lymphatic intervention, 24% with normal, and 76% with abnormal liver lymphatics. There was no difference in length of hospital stay or mortality between the two groups, but there was a prolonged time to symptom resolution (p = .006) and persistent symptoms after 6 months (5% vs 44%, p = .002) in the group with abnormal liver lymphatics. CONCLUSION: We identified five liver lymphatic imaging categories with a substantial correlation to presenting lymphatic disease. Abnormal imaging patterns correlated with increased morbidity. Evaluation of liver lymphatics should be considered in patients with a systemic lymphatic disease if central lymphatic imaging is normal. KEY POINTS: • We identified five liver lymphatic imaging patterns: normal, hepatoperitoneal, hepatomesenteric, hepatopulmonary, and hepatoduodenal. • Imaging patterns were correlated with disease presentation (normal - chylothorax/PB, hepatoperitoneal - ascites/chylothorax, hepatopulmonary - chylothorax/PB, hepatoduodenal - PLE). • Abnormal imaging patterns correlated with increased morbidity.

Dynamic Contrast Magnetic Resonance Lymphangiography Localizes Lymphatic Leak to the Duodenum in Protein-Losing Enteropathy.

OBJECTIVES: Protein-losing enteropathy (PLE) is a disorder of intestinal lymphatic flow resulting in leakage of protein-rich lymph into the gut lumen. Our primary aim was to report the imaging findings of dynamic contrast magnetic resonance lymphangiography (DCMRL) in patients with PLE. Our secondary objective was to use these imaging findings to characterize lymphatic phenotypes. METHODS: Single-center retrospective cohort study of patients with PLE unrelated to single-ventricle circulation who underwent DCMRL. We report imaging findings of intranodal (IN), intrahepatic (IH), and intramesenteric (IM) access points for DCMRL. RESULTS: Nineteen patients 0.3-58 years of age (median 1.2 years) underwent 29 DCMRL studies. Primary intestinal lymphangiectasia (PIL) was the most common referring diagnosis (42%). Other etiologies included constrictive pericarditis, thoracic insufficiency syndrome, and genetic disorders. IN-DCMRL demonstrated a normal central lymphatic system in all patients with an intact thoracic duct and localized duodenal leak in one patient (1/19, 5%). IH-DCMRL detected a duodenal leak in 12 of 17 (71%), and IM-DCMRL detected duodenal leak in 5 of 6 (83%). Independent of etiology, lymphatic leak was only visualized in the duodenum. CONCLUSIONS: In patients with PLE, imaging via DCMRL reveals that leak is localized to the duodenum regardless of etiology. Comprehensive imaging evaluation with three access points can provide detailed information about the site of duodenal leak.

Dynamic contrast-enhanced magnetic resonance lymphangiography.

Lymphatic flow disorders include a broad spectrum of abnormalities that can originate in the lymphatic or the venous system. The development of these disorders is multifactorial and is most commonly associated with congenital heart diseases and palliative surgeries that these patients undergo. Central lymphatic disorders might be secondary to traumatic leaks, lymphatic overproduction, conduction abnormalities or lymphedema, and they can progress to perfusion anomalies. Several imaging modalities have been used to visualize the lymphatic system. However, the imaging of central lymphatic flow has always been challenging. Dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL) allows for visualization of central lymphatic flow disorders and has been recently applied for the assessment of plastic bronchitis, protein-losing enteropathy, chylothorax and chylopericardium, among other lymphatic disorders. The hepatic and mesenteric accesses are innovative and promising techniques for better identification and understanding of these abnormalities. The main objectives of this review are to discuss the physiology and anatomy of the lymphatic system and review the current uses of DCMRL in the diagnosis and management of lymphatic flow disorders.

Central venous catheter fracture leading to TPN extravasation and abdominal compartment syndrome diagnosed with bedside contrast-enhanced ultrasound.

Central venous lines may require contrast injection under fluoroscopy to evaluate for dysfunction such as occlusion, fibrin sheath development or catheter fracture. Rarely, some patients may be too ill to travel to the interventional radiology suite for this examination. We present a case utilizing contrast-enhanced ultrasound (CEUS) at the bedside to assess catheter integrity in a critically ill infant with a large intra-abdominal fluid collection. CEUS demonstrated extravasation into the collection, confirming catheter fracture and prompting immediate cessation of line use and recommendation for exchange. This case shows the utility of CEUS to evaluate central venous access devices in children who are unable to travel to interventional radiology for a standard contrast injection.

Intramesenteric dynamic contrast pediatric MR lymphangiography: initial experience and comparison with intranodal and intrahepatic MR lymphangiography.

OBJECTIVES: To report on our initial experience with intramesenteric (IM) dynamic contrast magnetic resonance lymphangiography (DCMRL) for evaluation of the lymphatics in patients with concern for mesenteric lymphatic flow disorders and to compare IM-DCMRL with intrahepatic (IH) and intranodal (IN) DCMRL. METHODS: This is a retrospective review of imaging findings in 15 consecutive patients who presented with protein losing enteropathy (PLE) and/or ascites undergoing IM-DCMRL, IH-DCMRL, and IN-DCMRL. The IM-DCMRL technique involves the injection of a gadolinium contrast agent into the mesenteric lymphatic ducts or lymph nodes followed by imaging of the abdomen and chest with dynamic time-resolved MR lymphangiography. RESULTS: IM-DCMRL was successfully performed in 14/15 (93%) of the patients. When comparing IN-DCMRL with IM-DCMRL, there was a significant difference in the visualization of dermal backflow (p = 0.014), duodenal perfusion (p = 0.003), duodenal leak (p = 0.014), and peritoneal leak (p = 0.003). IM-DCMRL demonstrated peritoneal leak in 7 patients in contrast to IH-DCMRL which demonstrated leak in 4 patients and IN-DCMRL which did not demonstrate any peritoneal leaks. Duodenal leaks were seen by IH-DCMRL in 9 patients versus 5 with IM-DCMRL and none with IN-DCMRL. In one patient with congenital PLE, the three modalities showed different disconnected flow patterns with duodenal leak only seen by IM-DCMRL. There were no short-term complications from the procedures. CONCLUSIONS: IM-DCMRL is a feasible imaging technique for evaluation of the mesenteric lymphatics. In certain mesenteric lymphatic flow abnormalities, such as PLE and ascites, this imaging may be helpful for diagnosis and the planning of interventions and warrants further studies. KEY POINTS: • Intramesenteric dynamic contrast magnetic resonance lymphangiography (IM-DCMRL) is a new imaging technique to evaluate mesenteric lymphatic flow disorders such as ascites. • IM-DCMRL is able to image lymphatic leaks in patients with ascites and protein losing enteropathy not seen with intranodal (IN-DCMRL) imaging.

Pediatric pulmonary lymphatic flow Disorders: Diagnosis and management.

Pulmonary lymphatic flow disorders involve the abnormal lymphatic flow via lymphatic channels to the lungs and pleural space. Plastic bronchitis and chylothorax are the main complications of this abnormal lymphatic perfusion, which has been termed pulmonary lymphatic perfusion syndrome (PLPS). Following lymphatic access, dynamic contrast MR lymphangiography is the imaging modality of choice to diagnose these disorders. Management includes medical therapy, percutaneous interventions under fluoroscopy, and surgical interventions.

Imaging of fetal lymphangiectasias: prenatal and postnatal imaging findings.

Lymphangiectasias are lymphatic malformations characterized by the abnormal dilation and morphology of the lymphatic channels. The classification and treatment of these disorders can be challenging given the limited amount of literature available in children. Various imaging modalities are used to confirm suspected diagnosis, plan the most appropriate treatment, and estimate a prognosis. Prenatal evaluation is performed using both prenatal US imaging and fetal MRI. These modalities are paramount for appropriate parental counseling and planning of perinatal care. During the neonatal period, chest US imaging is a useful modality to evaluate pulmonary lymphangiectasia because other modalities such as conventional radiography and CT display nonspecific findings. Finally, the recent breakthroughs in lymphatic imaging with MRI have allowed us to better classify lymphatic disorders. Dynamic contrast-enhanced lymphangiography, conventional lymphangiography and percutaneous lymphatic procedures offer static and dynamic evaluation of the central conducting lymphatics in children, with excellent spatial resolution and the possibility to provide treatment. The purpose of this review is to discuss the normal and abnormal development of the fetal lymphatic system and how to best depict it by imaging during the prenatal and postnatal life.

Implantable venous access devices in children with severe hemophilia: a tertiary pediatric institutional experience.

BACKGROUND: Clotting factor replacement forms the pillar of treatment for children with hemophilia. Most children can be treated using peripheral venipuncture, but very young children and children with poor venous access might require a central venous catheter. Short-term and long-term complications of implantable venous access device placement (also known as port placement) can result in important morbidity and mortality in children with hemophilia. OBJECTIVE: The purpose of this study is to describe our experience with port placement in children and adolescents with severe hemophilia (<1% of the Factors VIII or IX). MATERIALS AND METHODS: We performed a retrospective review over a 10-year period to identify port placement in pediatric patients with severe hemophilia. We reviewed demographic and procedural information, access frequency, mechanical complications, and central-line-associated bloodstream infections (CLABSI). Eighteen males were included, with median age at insertion of 3.9 years (0.7-22.7 years). Fifteen of the 18 patients had hemophilia Type A and 3/18 had Type B. Thirteen had high neutralizing inhibitor titers. RESULTS: Technical success in port placement was achieved in 26/27 (96.3%) patients, with 1 port failure caused by venous occlusion from prior catheter placement. Port catheter size ranged from 5 French (Fr) to 7.5 Fr. All were single-lumen and placed via right (76.9%) or left (23.1%) internal jugular vein; 59.3% were placed during general anesthesia, and all had factor replacement prophylaxis. A peripherally inserted central catheter (PICC) was placed concurrently in 69.2% of the cases; per hospital policy, the port was only accessed 15 days post-placement to reduce the risk of site hematoma. Two patients were lost to follow-up. The total catheter days was 15,893. Ports were removed in 14/24 cases, most commonly because of CLABSI (7/24; 29.2%) and transition to peripheral infusion (3/24; 12.5%). Bleeding was the most common complication in the first 30 days after placement. There were nine CLABSI events (0.57 per 1,000 catheter days), all in patients with high neutralizing inhibitor titers. A higher frequency of port access (more or equal to daily vs. less than daily) correlated with higher infection rates (P=0.02). Median time from port insertion to first infection was 348 days (range 167-1,055 days). There were four fibrin-sheath-related catheter occlusions (0.25 per 1,000 catheter days): three catheters were salvaged with intra-catheter tissue plasminogen activator (tPA) instillation resulting in a salvage of an additional 1,214 catheter days, and one catheter was removed after tPA failure (0.06 per 1,000 catheter days). CONCLUSION: Port maintenance in boys with severe hemophilia is challenging given the need for long-term frequent device access that is associated with catheter-related infections. The rate of bleeding or infection did not differ in patients whether the device was accessed immediately or 15 days post placement. With appropriate pre- and post-procedural factor replacement, immediate and early term severe complications are not common.

Roles of Bacillus subtilis RecA, Nucleotide Excision Repair, and Translesion Synthesis Polymerases in Counteracting Cr(VI)-Promoted DNA Damage.

Bacteria deploy global programs of gene expression, including components of the SOS response, to counteract the cytotoxic and genotoxic effects of environmental DNA-damaging factors. Here we report that genetic damage promoted by hexavalent chromium elicited the SOS response in Bacillus subtilis, as evidenced by the induction of transcriptional uvrA-lacZ, recA-lacZ, and P recA-gfp fusions. Accordingly, B. subtilis strains deficient in homologous recombination (RecA) and nucleotide excision repair (NER) (UvrA), components of the SOS response, were significantly more sensitive to Cr(VI) treatment than were cells of the wild-type strain. These results strongly suggest that Cr(VI) induces the formation in growing B. subtilis cells of cytotoxic and genotoxic bulky DNA lesions that are processed by RecA and/or the NER pathways. In agreement with this notion, Cr(VI) significantly increased the formation of DNA-protein cross-links (DPCs) and induced mutagenesis in recA- and uvrA-deficient B. subtilis strains, through a pathway that required YqjH/YqjW-mediated translesion synthesis. We conclude that Cr(VI) promotes mutagenesis and cell death in B. subtilis by a mechanism that involves the formation of DPCs and that such deleterious effects are counteracted by both the NER and homologous recombination pathways, belonging to the RecA-dependent SOS system.IMPORTANCE It has been shown that, following permeation of cell barriers, Cr(VI) kills B. subtilis cells following a mechanism of reactive oxygen species-promoted DNA damage, which is counteracted by the guanine oxidized repair system. Here we report a distinct mechanism of Cr(VI)-promoted DNA damage that involves production of DPCs capable of eliciting the bacterial SOS response. We also report that the NER and homologous recombination (RecA) repair pathways, as well as low-fidelity DNA polymerases, counteract this metal-induced mechanism of killing in B. subtilis Hence, our results contribute to an understanding of how environmental pollutants activate global programs of gene expression that allow bacteria to contend with the cytotoxic and genotoxic effects of heavy metals.

A novel technique for removing a fibrin sheath from a mediport catheter in the pediatric population.

Mediport (also known as port, portacath or Infusaport) is a commonly placed central venous access in pediatric patients. Fibrin sheath formation around the central venous catheter is a common biological response leading to port malfunction in the form of inability to aspirate but preserved capacity for infusion of fluids. If fibrinolytic therapy fails, percutaneous fibrin sheath stripping via transfemoral route or replacement with a new mediport are routine/conventional treatments for a fibrin sheath. We describe a novel technique for removing a fibrin sheath by exteriorizing the catheter through the neck entry site, stripping the fibrin sheath from the catheter manually under sterile conditions and replacing the catheter via a peel-away sheath introduced through the same skin incision as an alternative to complete port replacement or attempted catheter stripping.

A new species of Branchellion Savigny, 1822 (Hirudinida: Piscicolidae), a marine leech parasitic on the giant electric ray Narcine entemedor Jordan & Starks (Batoidea: Narcinidae) off Oaxaca, Mexico.

Branchellion spindolaorum n. sp. (Hirudinida: Piscicolidae) is described based on specimens found parasitising the giant electric ray Narcine entemedor Jordan & Starks off the coast of Oaxaca, Mexico. The new species can be clearly distinguished from the other species of Branchellion Savigny, 1822 by the presence of 30 pairs of lateral branchiae and 10 pairs of pulsatile vesicles. The definition of the genus Branchellion is expanded to include species with either 30, 31 or 33 pairs of foliaceous (plate-like) lateral branchiae in the urosome. In addition, we provide for the first time for the genus, scanning electron micrographs of the secondary suckers located on the ventral surface of the posterior sucker. Additionally, partial DNA sequences of the mitochondrial cytochrome c oxidase subunit 1 (cox1) were generated and compared with homologous sequences of other species of the genus. Branchellion spindolaorum n. sp. represents the fourth species of the genus known in the Eastern Pacific and the first record of a leech parasitising N. entemedor.

Role of Bacillus subtilis DNA Glycosylase MutM in Counteracting Oxidatively Induced DNA Damage and in Stationary-Phase-Associated Mutagenesis.

UNLABELLED: Reactive oxygen species (ROS) promote the synthesis of the DNA lesion 8-oxo-G, whose mutagenic effects are counteracted in distinct organisms by the DNA glycosylase MutM. We report here that in Bacillus subtilis, mutM is expressed during the exponential and stationary phases of growth. In agreement with this expression pattern, results of a Western blot analysis confirmed the presence of MutM in both stages of growth. In comparison with cells of a wild-type strain, cells of B. subtilis lacking MutM increased their spontaneous mutation frequency to Rif(r) and were more sensitive to the ROS promoter agents hydrogen peroxide and 1,1'-dimethyl-4,4'-bipyridinium dichloride (Paraquat). However, despite MutM's proven participation in preventing ROS-induced-DNA damage, the expression of mutM was not induced by hydrogen peroxide, mitomycin C, or NaCl, suggesting that transcription of this gene is not under the control of the RecA, PerR, or σ(B) regulons. Finally, the role of MutM in stationary-phase-associated mutagenesis (SPM) was investigated in the strain B. subtilis YB955 (hisC952 metB5 leuC427). Results revealed that under limiting growth conditions, a mutM knockout strain significantly increased the amount of stationary-phase-associated his, met, and leu revertants produced. In summary, our results support the notion that the absence of MutM promotes mutagenesis that allows nutritionally stressed B. subtilis cells to escape from growth-limiting conditions. IMPORTANCE: The present study describes the role played by a DNA repair protein (MutM) in protecting the soil bacterium Bacillus subtilis from the genotoxic effects induced by reactive oxygen species (ROS) promoter agents. Moreover, it reveals that the genetic inactivation of mutM allows nutritionally stressed bacteria to escape from growth-limiting conditions, putatively by a mechanism that involves the accumulation and error-prone processing of oxidized DNA bases.