An Adaptor Hierarchy Regulates Proteolysis during a Bacterial Cell Cycle.

Regulated protein degradation is essential. The timed destruction of crucial proteins by the ClpXP protease drives cell-cycle progression in the bacterium Caulobacter crescentus. Although ClpXP is active alone, additional factors are inexplicably required for cell-cycle-dependent proteolysis. Here, we show that these factors constitute an adaptor hierarchy wherein different substrates are destroyed based on the degree of adaptor assembly. The hierarchy builds upon priming of ClpXP by the adaptor CpdR, which promotes degradation of one class of substrates and also recruits the adaptor RcdA to degrade a second class of substrates. Adding the PopA adaptor promotes destruction of a third class of substrates and inhibits degradation of the second class. We dissect RcdA to generate bespoke adaptors, identifying critical substrate elements needed for RcdA recognition and uncovering additional cell-cycle-dependent ClpXP substrates. Our work reveals how hierarchical adaptors and primed proteases orchestrate regulated proteolysis during bacterial cell-cycle progression.

Regulated Proteolysis in Bacteria: Caulobacter.

Protein degradation is essential for all living things. Bacteria use energy-dependent proteases to control protein destruction in a highly specific manner. Recognition of substrates is determined by the inherent specificity of the proteases and through adaptor proteins that alter the spectrum of substrates. In the α-proteobacterium Caulobacter crescentus, regulated protein degradation is required for stress responses, developmental transitions, and cell cycle progression. In this review, we describe recent progress in our understanding of the regulated and stress-responsive protein degradation pathways in Caulobacter. We discuss how organization of highly specific adaptors into functional hierarchies drives destruction of proteins during the bacterial cell cycle. Because all cells must balance the need for degradation of many true substrates with the toxic consequences of nonspecific protein destruction, principles found in one system likely generalize to others.

Transitional Hemodynamics in Neonates Born Through Meconium-Stained Amniotic Fluid: A Prospective Observational Study.

Neonates born through meconium-stained amniotic fluid (MSAF) are at increased risk of altered cardiopulmonary transition at birth. There is a paucity of literature evaluating the transitional hemodynamics in these neonates. We aimed to evaluate transitional hemodynamics via echocardiography in neonates born through MSAF, compared to healthy neonates. The primary objective was to assess pulmonary vascular resistance using left pulmonary artery-velocity time integral (LPA-VTI). The secondary objectives were to assess other pulmonary vascular parameters and myocardial function. We enrolled 35 MSAF-born and 35 healthy neonates. Echocardiography was performed at 24 and 48 h of life by a pediatric cardiologist. Echocardiographic parameters were compared between MSAF-born and healthy neonates, and between MSAF-born neonates who developed meconium aspiration syndrome (MAS) and who did not (non-MAS). Among 35 MSAF-born neonates, 14 (40%) were non-vigorous, 18 (51%) required admission to neonatal intensive care unit, 8 (23%) developed MAS, 3 (9%) pulmonary hypertension and 1 (3%) air leak. On echocardiography, LPA-VTI (cm; mean ± SD) was significantly decreased at 24 and 48 h in MSAF-born neonates (14.38 ± 2.48; 15.55 ± 2.48), compared to healthy neonates (16.60 ± 2.14; 17.66 ± 2.71), respectively. Further, LPA-VTI was significantly reduced at 24 and 48 h among MAS (11.81 ± 3.0; 12.43 ± 2.5), compared to non-MAS neonates (15.15 ± 1.72; 16.48 ± 1.55), respectively. Other pulmonary vascular and myocardial function parameters were comparable between the two groups. Pulmonary adaptation was significantly delayed in neonates with MSAF, which was more pronounced in MAS neonates. Further studies should explore the utility of these parameters for early prediction of cardiorespiratory morbidities in this population.

The impact of mechanical oesophageal deviation on posterior wall pulmonary vein reconnection.

AIMS: During atrial fibrillation ablation, oesophageal heating typically prompts reduction or termination of radiofrequency energy delivery. We previously demonstrated oesophageal temperature rises are associated with posterior left atrial pulmonary vein reconnection (PVR) during redo procedures. In this study, we assessed whether mechanical oesophageal deviation (MED) during an index procedure minimizes posterior wall PVRs during redo procedures. METHODS AND RESULTS: Patients in whom we performed a first-ever procedure followed by a clinically driven redo procedure were divided based on both the use of MED for oesophageal protection and the ablation catheter employed (force or non-force sensing) in the first procedure. The PVR sites were compared between MED using a force-sensing catheter (MEDForce), or no MED with a non-force (ControlNoForce) or force (ControlForce) sensing catheter. Despite similar clinical characteristics, the MEDForce redo procedure rate (9.2%, 26/282 patients) was significantly less than the ControlNoForce (17.2%, 126/734 patients; P = 0.002) and ControlForce (17.5%, 20/114 patients; P = 0.024) groups. During the redo procedure, the posterior PVR rate with MEDForce (2%, 1/50 PV pairs) was significantly less than with either ControlNoForce (17.7%, 44/249 PV pairs; P = 0.004) or ControlForce (22.5%, 9/40 PV pairs; P = 0.003), or aggregate Controls (18.3%, 53/289 PV pairs; P = 0.006). However, the anterior PVR rate with MEDForce (8%, 4/50 PV pairs) was not significantly different than Controls (aggregate Controls-3.5%, 10/289 PV pairs, P = 0.136; ControlNoForce-2.4%, 6/249 PV pairs, P = 0.067; ControlForce-10%, 4/40 PV pairs, P = 1.0). CONCLUSION: Oesophageal deviation improves the durability of the posterior wall ablation lesion set during AF ablation.

Polar Localization Hub Protein PopZ Restrains Adaptor-Dependent ClpXP Proteolysis in Caulobacter crescentus.

In Caulobacter crescentus, timely degradation of several proteins by the ClpXP protease is critical for proper cell cycle progression. During the cell cycle, the ClpXP protease, the substrate CtrA, and many other proteins are localized to the stalked pole dependent on a polar interaction hub composed of PopZ protein oligomers. Prior work suggests that the localization of ClpXP, protease substrates, and cofactors is needed for recognition of substrates, such as CtrA, by ClpXP. Here, we formally test this hypothesis by examining the role of PopZ in ClpXP activity and find, surprisingly, that CtrA degradation is enhanced in cells lacking polar localization due to loss of PopZ. The ClpXP adaptor CpdR is required for this enhanced degradation of CtrA and other adaptor-dependent substrates, but adaptor-independent substrate degradation is not affected upon loss of PopZ. We find that overexpression of PopZ also leads to faster degradation of CtrA but is likely due to nonphysiologically relevant recognition of CtrA by ClpXP alone, as loss of CpdR does not affect this enhancement. Our main conclusion is that loss of PopZ, and therefore loss of polar localization, does not result in the loss of ClpXP-regulated proteolysis, as would be predicted from a model which requires polar localization of ClpXP for its activation. Rather, our data point to a model where PopZ normally restrains ClpXP proteolysis by promoting the inactivation of the CpdR adaptor, perhaps through the activity and localization of the CckA kinase.IMPORTANCE Regulated proteolysis is critical for the cell cycle progression of bacteria, such as Caulobacter crescentus According to one model, this regulated proteolysis requires localization of the ClpXP protease at the stalked pole for its subsequent degradation of substrates, such as CtrA. This study offers evidence that supports an alternative model to explain how localization might influence protein degradation. Using a delocalized in vivo system created by the deletion of a polar organizing protein, PopZ, we show that activation of the ClpXP protease is independent of its polar localization. The data point to a role for PopZ in restraining ClpXP activity, likely by controlling the activity of upstream regulators of protease activity, such as CckA, though changes in its localization.

Cargo engagement protects protease adaptors from degradation in a substrate-specific manner.

Protein degradation in bacteria is a highly controlled process involving proteolytic adaptors that regulate protein degradation during cell cycle progression or during stress responses. Many adaptors work as scaffolds that selectively bind cargo and tether substrates to their cognate proteases to promote substrate destruction, whereas others primarily activate the target protease. Because adaptors must bind their cognate protease, all adaptors run the risk of being recognized by the protease as substrates themselves, a process that could limit their effectiveness. Here we use purified proteins in a reconstituted system and in vivo studies to show that adaptors of the ClpXP protease are readily degraded but that cargo binding inhibits this degradation. We found that this principle extends across several adaptor systems, including the hierarchical adaptors that drive the Caulobacter bacterial cell cycle and the quality control adaptor SspB. We also found that the ability of a cargo to protect its adaptor is adaptor substrate-specific, as adaptors with artificial degradation tags were not protected even though cargo binding is unaffected. Our work points to an optimization of inherent adaptor degradation and cargo binding that ensures that robust adaptor activity is maintained when high amounts of substrate must be delivered and that adaptors can be eliminated when their tasks have been completed.

Cell cycle-dependent adaptor complex for ClpXP-mediated proteolysis directly integrates phosphorylation and second messenger signals.

The cell-division cycle of Caulobacter crescentus depends on periodic activation and deactivation of the essential response regulator CtrA. Although CtrA is critical for transcription during some parts of the cell cycle, its activity must be eliminated before chromosome replication because CtrA also blocks the initiation of DNA replication. CtrA activity is down-regulated both by dephosphorylation and by proteolysis, mediated by the ubiquitous ATP-dependent protease ClpXP. Here we demonstrate that proteins needed for rapid CtrA proteolysis in vivo form a phosphorylation-dependent and cyclic diguanylate (cdG)-dependent adaptor complex that accelerates CtrA degradation in vitro by ClpXP. The adaptor complex includes CpdR, a single-domain response regulator; PopA, a cdG-binding protein; and RcdA, a protein whose activity cannot be predicted. When CpdR is unphosphorylated and when PopA is bound to cdG, they work together with RcdA in an all-or-none manner to reduce the Km of CtrA proteolysis 10-fold. We further identified a set of amino acids in the receiver domain of CtrA that modulate its adaptor-mediated degradation in vitro and in vivo. Complex formation between PopA and CtrA depends on these amino acids, which reside on alpha-helix 1 of the CtrA receiver domain, and on cdG binding by PopA. These results reveal that each accessory factor plays an essential biochemical role in the regulated proteolysis of CtrA and demonstrate, to our knowledge, the first example of a multiprotein, cdG-dependent proteolytic adaptor.

Real world utilization and impact of the wearable cardioverter-defibrillator in a community setting.

INTRODUCTION: The wearable cardioverter-defibrillator (WCD) is used in patients at risk for sudden cardiac death (SCD) but not immediate candidates for intracardiac defibrillator (ICD) implantation. METHODS: We performed a single center retrospective study of patients prescribed WCD upon hospital discharge from January 2002 to October 2015. Clinical characteristics were obtained from the hospital electronic database and device data from Zoll LifeVest database. RESULTS: Of 140 patients, 62% were men, 85.9% were African-American and mean age was 58.2 ± 15.5 years. Ischemic cardiomyopathy was present in 45 (32%) and non-ischemic cardiomyopathy in 64 patients (46%). Mean left ventricular ejection fraction (EF) was 0.28 ± 0.4. WCD was worn for 7657 patient-days (21 patient-years), with each patient using WCD for median of 43 days (IQR: 7-83 days), and daily mean use 17.3 ± 7.5 h. There were a total of 6 (4.2%) WCD shocks of which 2 (1.4%) were appropriate (one for VT, one for VF) and 4 (2.8%) were inappropriate (2 had supraventricular tachycardia, 2 had artifact). Two patients who received appropriate shocks were African-American with non-ischemic cardiomyopathy (EF<20%), non-sustained VT and wide QRS duration. Upon termination of WCD use, 45 (32%) received ICD while EF improved in 34 patients (32%). CONCLUSIONS: In a predominantly minority, community setting, WCD compliance is high and use is effective in aborting SCD. However, inappropriate shocks do occur. A significant proportion of patients did not ultimately require ICD implantation suggesting this may be a cost-effective strategy in patients at risk of SCD.

Use of the new contact force sensing ablation catheter dramatically reduces fluoroscopy time during atrial fibrillation ablation procedures.

OBJECTIVES: To study the impact of contact force (CF) sensing on fluoroscopy, procedure, left atrial (LA) and ablation times and number of ablations during atrial fibrillation (AF) ablation. BACKGROUND: Catheter ablation is an effective treatment for symptomatic AF. Recently a new ablation catheter providing real-time CF has been approved for use. METHODS: A nested case-control study was performed comparing radiofrequency ablation of AF using the irrigated CF-sensing ThermoCool SmartTouch catheter versus open-irrigated ThermoCool SF catheter (Biosense Webster, Inc., Diamond Bar, California). Demographic and procedure data were obtained and student t-test was used to compare data between groups. RESULTS: Thirty consecutive adult patients were included with 15 patients in each group. Mean fluoroscopy time was significantly lower in CF group (19.4 ± 8 vs 40.7 ± 8 min, p < 0.0001). LA time was significantly lower in CF group (151.7 ± 44 vs 185.7 ± 35 min, p = 0.01). There were no significant differences in procedure time between CF and SF groups (204 ± 37 vs 207 ± 36 min) and ablation time (121 ± 32 vs 122 ± 37 min). When patients who only underwent pulmonary vein isolation (PVI) were compared, fluoroscopy time was significantly lower in CF group (18 ± 9 vs 37.8 ± 5 min, p < 0.0001) as was LA time (141.4 ± 39 vs 171.8 ± 30 min, p = 0.04). Fluoroscopy time was also significantly lower in CF subgroup with additional ablation (20.9 ± 7 vs 44.9 ± 10 min, p < 0.001). CONCLUSION: Use of CF-sensing catheter significantly reduced fluoroscopy and LA times during AF ablation with similar acute efficacy.

Regulated proteolysis of a transcription factor complex is critical to cell cycle progression in Caulobacter crescentus.

Cell cycle transitions are often triggered by the proteolysis of key regulatory proteins. In Caulobacter crescentus, the G1-S transition involves the degradation of an essential DNA-binding response regulator, CtrA, by the ClpXP protease. Here, we show that another critical cell cycle regulator, SciP, is also degraded during the G1-S transition, but by the Lon protease. SciP is a small protein that binds directly to CtrA and prevents it from activating target genes during G1. We demonstrate that SciP must be degraded during the G1-S transition so that cells can properly activate CtrA-dependent genes following DNA replication initiation and the reaccumulation of CtrA. These results indicate that like CtrA, SciP levels are tightly regulated during the Caulobacter cell cycle. In addition, we show that formation of a complex between CtrA and SciP at target promoters protects both proteins from their respective proteases. Degradation of either protein thus helps trigger the destruction of the other, facilitating a cooperative disassembly of the complex. Collectively, our results indicate that ClpXP and Lon each degrade an important cell cycle regulator, helping to trigger the onset of S phase and prepare cells for the subsequent programmes of gene expression critical to polar morphogenesis and cell division.

Birds and environment: a multidisciplinary approach to ecological, behavioural and conservation issues.

Birds perform significant ecosystem services in the environment. Nevertheless, they have been facing threats to their survival globally. This special collection assembles diverse articles on various aspects of birds' life, their interactions with the environment, their adaptations, and threats they have been facing along with conservation measures.

Robust superconductivity and the suppression of charge-density wave in the quasi-skutteruditesCa3(Ir1-xRhx)4Sn13single crystals at ambient pressure.

Single crystals of the quasi-skutterudite compounds Ca3(Ir1-xRhx)4Sn13(3-4-13) were synthesized by flux growth and characterized by x-ray diffraction, energy dispersive x-ray spectroscopy, magnetization, resistivity, and radio frequency magnetic susceptibility techniques. The coexistence and competition between the charge density wave (CDW) and superconductivity was studied by varying the Rh/Ir ratio. The superconducting transition temperature,Tc, varies from 7 K in pure Ir (x = 0) to 8.3 K in pure Rh (x = 1). Temperature-dependent electrical resistivity reveals monotonic suppression of the CDW transition temperature,TCDW(x). The CDW starts in pure Ir,x = 0, atTCDW≈ 40 K and extrapolates roughly linearly to zero atxc≈0.53-0.58 under the superconducting dome. Magnetization and transport measurements show a significant influence of CDW on superconducting and normal states. Meissner expulsion is substantially reduced in the CDW region, indicating competition between the CDW and superconductivity. The low-temperature resistivity is higher in the CDW part of the phase diagram, consistent with the reduced density of states due to CDW gapping. Its temperature dependence just aboveTcshows signs of non-Fermi liquid behavior in a cone-like composition pattern. We conclude that the Ca3(Ir1-xRhx)4Sn13alloy is a good candidate for a composition-driven quantum critical point at ambient pressure.

Suspect the Unexpected: A Rare Association of Autoimmune Hemolytic Anemia and Hemophagocytic Lymphohistiocytosis with Visceral Leishmaniasis: A Case Report and Review of Literature.

Visceral leishmaniasis is a common tropical infection presenting with a myriad of hematological abnormalities. We report an unusual case of an 11-year-old girl suffering from a febrile illness with hepatosplenomegaly and anemia. Laboratory findings included pancytopenia and hyperbilirubinemia. The leishmania antigen rK39 was positive and bone marrow examination revealed hemophagocytosis and amastigote forms of Leishmania donovani. Direct Coombs' test was positive (warm type, IgG) and LDH was elevated. Tests for other infections were negative. A diagnosis of visceral leishmaniasis with autoimmune hemolytic anemia (warm antibody type, IgG) with hemophagocytic lymphohistiocytosis was made. Patient showed response with anti-leishmanial treatment with improvement in clinical condition.

A Case of Fibrinous Pericardial Effusion: Masquerading Presentation of Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder with varied presentations varying from nonspecific features like fever, malaise, and arthralgia to serious manifestations like serositis (pleural, pericardial effusions), neurological manifestations, and renal involvement (lupus nephritis). SLE is a great mimicker, especially for infections like tuberculosis (TB) which is rampant in low- and middle-income countries (LMIC). We report a case of massive pericardial effusion, which was initially diagnosed as TB on clinico-radiological basis, but the diagnosis was later revised owing to new findings.

Fetal Hydantoin Syndrome: A Case Report.

Epilepsy is not a common cause of morbidity in pregnancy. It has widespread effects on maternal and fetal health necessitating adequate control of seizures. Many anti-seizure medications (ASM) have teratogenic effects on the fetus. We report a case of severe fetal hydantoin syndrome resulting in life-threatening major congenital anomalies. The mother was on phenytoin for the last three years and the pregnancy was not registered. We discuss various features of fetal hydantoin syndrome and the ideal management of epilepsy in pregnancy in brief.

Systemic Pseudohypoaldosteronism Type 1 Due to a Novel Mutation in SCNN1B Gene: A Case Report.

Pseudo hypoaldosteronism (PHA) is a type of channelopathy leading to life-threatening hyperkalemia, hyponatremia and metabolic acidosis in neonates. Type I PHA (PHAI) is characterized by either mutation in NR3C2 (MLR) gene or genes related to subunit of ENaC channel, whereas Type II (A to E) PHA is due to mutations in other genes. Type I PHA is further divided into systemic and renal forms based on the gene and organ involved. Systemic PHAI is a rare, multisystem disease presenting as severe salt wasting in neonates. In this article, we report a case of systemic pseudohypoaldosteronism type 1 in a 2 days old neonate with a novel mutation involving SCNN1B gene. Our patient appears to be the first reported case of systemic PHAI due to SCNN1B mutation from India.

Submandibular gland in squamous cell carcinoma of the tongue: Can preservation during neck dissection be a pragmatic option?

Context: The submandibular glands (SMGs) excision during head-and-neck oncosurgeries lead to significant morbidity and degradation of quality of life (QOL). The preservation of SMGs during head-and-neck oncosurgeries, without affecting oncological safety, will improve QOL by preventing xerostomia in these patients. Aims: The aim of this retrospective study was to assess the involvement of SMG by malignancy during neck dissection being done for the squamous cell carcinoma (SCC) of tongue and to evaluate oncological safety of SMG preservation in SCC of the tongue. Settings and Design: The study design was a retrospective analytical study. Subjects and Methods: The study included 391 patients of SCC of tongue operated at Quaternary oncological center from January 2016 to February 2020. The treatment records of 371 patients were reviewed for demographical data, nodal metastasis, and histopathological involvement of SMG by SCC. The statistical analysis was done using SPSS 22. Results: A total of 555 necks dissected were assessed, out of which 95 necks dissected were positive for nodal metastasis at level Ib. The SMG was involved by SCC in only two cases, both of which were poorly differentiated SCC. No intraglandular lymph nodes were detected in any of the SMG dissected. Conclusions: The study showed that involvement of the SMG by SCC of the tongue is not very common, and it may be possible to preserve the SMG during neck dissection in selected cases in SCC of the tongue. The preservation will definitely improve QOL of the patients, as excision of the SMG is one of the prominent factors, resulting in xerostomia.

Ethnomedicinal Use, Phytochemistry, and Other Potential Application of Aquatic and Semiaquatic Medicinal Plants.

Medicinal plants have been treating various ailments and diseases since ancient times. Aquatic and semiaquatic medicinal plants play an essential role in human welfare to fulfill their daily needs. They have shown biological, pharmacological, nutraceutical, and commercial applications. This review aims to collect and update all recent information on ethnomedicinal, phytochemistry, pharmacological activities, and nanoparticle synthesis and their uses in aquatic and semiaquatic medicinal plants. Original research papers, review papers, short communications, and book chapters on aquatic and semiaquatic plants have been retrieved from PubMed, Web of Science, Scopus, and Google Scholar. Keywords, ethnomedicinal studies, phytochemistry, pharmacological activities, and nanoparticle synthesis from aquatic and semiaquatic medicinal plants are used for the search. Different aquatic and semiaquatic medicinal plants belonging to the families Acanthaceae, Alismataceae, Amaranthaceae, Apiaceae, Araceae, Asteraceae, Boraginaceae, Ceratophyllaceae, Cyperaceae, Fabaceae, Hydrocharitaceae, Lythraceae, Marsileaceae, Menyanthaceae, Nelumbonaceae, Nymphaeaceae, Onagraceae, Plantaginaceae, Poaceae, Polygonaceae, Pontederiaceae, Primulaceae, Scrophulariaceae, and Zingiberaceae have been studied. They are rich in alkaloids, flavonoids, terpenoids, phenolics, saponins, tannins, dietary fiber, glycosidic derivatives, carbohydrates, and proteins. These phytochemicals have been used for their antimicrobial, antioxidant, hepatoprotective, sedative, anticonvulsant, cytotoxic, antiparasitic, and antidiabetic activities. Besides this, various parts of the plants are used as dietary supplements and green nanoparticle synthesis. These plants are also known for their commercial value and are used as an ingredient in some pharmaceutical industries.

Avian diversity in forest, agriculture and water stream habitats of Dehradun Valley, Uttarakhand, India.

The Western Himalaya is recognised for its biological diversity and ecological values. An attempt was made to understand the avian diversity distribution in Forest, Agriculture and Water stream habitats of Dehradun (Western Himalaya) Uttarakhand. A total of two hundred and thirty one species belonging to 54 families were encountered during the survey. Out of these, one endangered species (Egyptian Vulture, Neophron percnopterus) and three near-threatened species Alexandrine Parakeet (Psittacula eupatria), Black-necked Stork (Ephippiorhynchus asiaticu) and River Lapwing (Vanellus duvaucelii) and one vulnerable species Woolly-necked Stork (Ciconia episcopus) were sighted. Three avian species, Mistle Thrush, Sulphur-bellied Warbler and White-rumped Munia. have been recorded as isolates in the study area. The presence of these species indicates the habitats extension in Dehradun District of Uttarakhand. The present study provides significant records in the study site and provides a baseline data for future study with reference to conservation in Dehradun Region.