Discovery of a novel transcriptional regulator of sugar catabolism in archaea.

The haloarchaeon Haloferax volcanii degrades D-glucose via the semiphosphorylative Entner-Doudoroff pathway and D-fructose via a modified Embden-Meyerhof pathway. Here, we report the identification of GfcR, a novel type of transcriptional regulator that functions as an activator of both D-glucose and D-fructose catabolism. We find that in the presence of D-glucose, GfcR activates gluconate dehydratase, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase and also acts as activator of the phosphotransferase system and of fructose-1,6-bisphosphate aldolase, which are involved in uptake and degradation of D-fructose. In addition, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase are activated by GfcR in the presence of D-fructose and also during growth on D-galactose and glycerol. Electrophoretic mobility shift assays indicate that GfcR binds directly to promoters of regulated genes. Specific intermediates of the degradation pathways of the three hexoses and of glycerol were identified as inducer molecules of GfcR. GfcR is composed of a phosphoribosyltransferase (PRT) domain with an N-terminal helix-turn-helix motif and thus shows homology to PurR of Gram-positive bacteria that is involved in the transcriptional regulation of nucleotide biosynthesis. We propose that GfcR of H. volcanii evolved from a PRT-like enzyme to attain a function as a transcriptional regulator of central sugar catabolic pathways in archaea.

c-di-GMP regulates activity of the PlzA RNA chaperone from the Lyme disease spirochete.

PlzA is a c-di-GMP-binding protein crucial for adaptation of the Lyme disease spirochete Borrelia (Borreliella) burgdorferi during its enzootic life cycle. Unliganded apo-PlzA is important for vertebrate infection, while liganded holo-PlzA is important for survival in the tick; however, the biological function of PlzA has remained enigmatic. Here, we report that PlzA has RNA chaperone activity that is inhibited by c-di-GMP binding. Holo- and apo-PlzA bind RNA and accelerate RNA annealing, while only apo-PlzA can strand displace and unwind double-stranded RNA. Guided by the crystal structure of PlzA, we identified several key aromatic amino acids protruding from the N- and C-terminal domains that are required for RNA-binding and unwinding activity. Our findings illuminate c-di-GMP as a switch controlling the RNA chaperone activity of PlzA, and we propose that complex RNA-mediated modulatory mechanisms allow PlzA to regulate gene expression during both the vector and host phases of the B. burgdorferi life cycle.

Application of N-Terminal Site-Specific Biotin and Digoxigenin Conjugates to Clinical Anti-drug Antibody Assay Development.

Biotin- and digoxigenin (DIG)-conjugated therapeutic drugs are critical reagents used for the development of anti-drug antibody (ADA) assays for the assessment of immunogenicity. The current practice of generating biotin and DIG conjugates is to label a therapeutic antibody with biotin or DIG via primary amine groups on lysine or N-terminal residues. This approach modifies lysine residues nonselectively, which can impact the ability of an ADA assay to detect those ADAs that recognize epitopes located at or near the modified lysine residue(s). The impact of the lysine modification is considered greater for therapeutic antibodies that have a limited number of lysine residues, such as the variable heavy domain of heavy chain (VHH) antibodies. In this paper, for the first time, we report the application of site-specifically conjugated biotin- and DIG-VHH reagents to clinical ADA assay development using a model molecule, VHHA. The site-specific conjugation of biotin or DIG to VHHA was achieved by using an optimized reductive alkylation approach, which enabled the majority of VHHA molecules labeled with biotin or DIG at the desirable N-terminus, thereby minimizing modification of the protein after labeling and reducing the possibility of missing detection of ADAs. Head-to-head comparison of biophysical characterization data revealed that the site-specific biotin and DIG conjugates demonstrated overall superior quality to biotin- and DIG-VHHA prepared using the conventional amine coupling method, and the performance of the ADA assay developed using site-specific biotin and DIG conjugates met all acceptance criteria. The approach described here can be applied to the production of other therapeutic-protein- or antibody-based critical reagents that are used to support ligand binding assays.

Associations of neutral pH, low-GDP peritoneal dialysis solutions with patient survival, transfer to haemodialysis and peritonitis.

BACKGROUND: Peritoneal dialysis (PD) solutions containing low levels of glucose degradation products (GDPs) are associated with attenuation of peritoneal membrane injury and vascular complications. However, clinical benefits associated with neutral-pH, low-GDP (N-pH/L-GDP) solutions remain unclear. METHODS: Using data from the Australia and New Zealand Dialysis and Transplant Registry, we examined the associations between N-pH/L-GDP solutions and all-cause mortality, cause-specific mortality, transfer to haemodialysis (HD) for ≥30 days and PD peritonitis in adult incident PD patients in Australia and New Zealand between 1 January 2005 and 31 December 2020 using adjusted Cox regression analyses. RESULTS: Of 12 814 incident PD patients, 2282 (18%) were on N-pH/L-GDP solutions. The proportion of patients on N-pH/L-GDP solutions each year increased from 11% in 2005 to 33% in 2017. During the study period, 5330 (42%) patients died, 4977 (39%) experienced transfer to HD and 5502 (43%) experienced PD peritonitis. Compared with the use of conventional solutions only, the use of any form of N-pH/L-GDP solution was associated with reduced risks of all-cause mortality {adjusted hazard ratio [aHR] 0.67 [95% confidence interval (CI) 0.61-0.74]}, cardiovascular mortality [aHR 0.65 (95% CI 0.56-0.77)], infection-related mortality [aHR 0.62 (95% CI 0.47-0.83)] and transfer to HD [aHR 0.79 (95% CI 0.72-0.86)] but an increased risk of PD peritonitis [aHR 1.16 (95% CI 1.07-1.26)]. CONCLUSIONS: Patients who received N-pH/L-GDP solutions had decreased risks of all-cause and cause-specific mortality despite an increased risk of PD peritonitis. Studies assessing the causal relationships are warranted to determine the clinical benefits of N-pH/L-GDP solutions.

Subclassification of epithelioid sarcoma with potential therapeutic impact.

Epithelioid sarcoma is a rare and aggressive mesenchymal tumour, the genetic hallmark of which is the loss of expression of SMARCB1, a key member of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodelling complex. Hampered by its rarity, epithelioid sarcoma has received little research attention and therapeutic options for this disease remain limited. SMARCB1-deficient tumours also include malignant rhabdoid tumour, atypical teratoid and rhabdoid tumour, epithelioid malignant peripheral nerve sheath tumour, and poorly differentiated chordoma. Histologically, it can be challenging to distinguish epithelioid sarcoma from malignant rhabdoid tumour and other SMARCB1-deficient tumours, whereas methylation profiling shows that they represent distinct entities and facilitates their classification. Methylation studies on SMARCB1-deficient tumours, although not including epithelioid sarcomas, reported methylation subgroups which resulted in new clinical stratification and therapeutic approaches. In addition, emerging evidence indicates that immunotherapy, including immune checkpoint inhibitors, represents a promising therapeutic strategy for SMARCB1-deficient tumours. Here, we show that some epithelioid sarcomas share methylation patterns of malignant rhabdoid tumours indicating that this could help to distinguish these entities and guide treatment. Using gene expression data, we also showed that the immune environment of epithelioid sarcoma is characterised by a predominance of CD8+ lymphocytes and M2 macrophages. These findings have potential implications for the management of patients with epithelioid sarcoma. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Equatorial auroral records reveal dynamics of the paleo-West Pacific geomagnetic anomaly.

Localized regions of low geomagnetic intensity such as the South Atlantic Anomaly allow energetic particles from the Van Allen radiation belt to precipitate into the atmosphere and have been linked to a signature in the form of red aurora-like airglow visible to the naked eye. Smoothed global geomagnetic models predict a low-intensity West Pacific Anomaly (WPA) during the sixteenth to nineteenth centuries characterized by a simple time dependence. Here, we link the WPA to an independent database of equatorial aurorae recorded in Seoul, South Korea. These records show a complex fluctuating behavior in auroral frequency, whose overall trend from 1500 to 1800 AD is consistent with the locally weak geomagnetic field of the WPA, with a minimum at 1650 AD. We propose that the fluctuations in auroral frequency are caused by corresponding and hitherto unknown fluctuations in the regional magnetic intensity with peaks at 1590 and 1720 AD, a time dependence that has been masked by the smoothing inherent in regularized global geomagnetic models. A physical core flow model demonstrates that such behavior requires localized time-dependent upwelling flows in the Earth's core, possibly driven by regional lower-mantle anomalies.

Discovery of a caspase cleavage motif antibody reveals insights into noncanonical inflammasome function.

Inflammasomes sense a number of pathogen and host damage signals to initiate a signaling cascade that triggers inflammatory cell death, termed pyroptosis. The inflammatory caspases (1/4/5/11) are the key effectors of this process through cleavage and activation of the pore-forming protein gasdermin D. Caspase-1 also activates proinflammatory interleukins, IL-1ß and IL-18, via proteolysis. However, compared to the well-studied apoptotic caspases, the identity of substrates and therefore biological functions of the inflammatory caspases remain limited. Here, we construct, validate, and apply an antibody toolset for direct detection of neo-C termini generated by inflammatory caspase proteolysis. By combining rabbit immune phage display with a set of degenerate and defined target peptides, we discovered two monoclonal antibodies that bind peptides with a similar degenerate recognition motif as the inflammatory caspases without recognizing the canonical apoptotic caspase recognition motif. Crystal structure analyses revealed the molecular basis of this strong yet paradoxical degenerate mode of peptide recognition. One antibody selectively immunoprecipitated cleaved forms of known and unknown inflammatory caspase substrates, allowing the identification of over 300 putative substrates of the caspase-4 noncanonical inflammasome, including caspase-7. This dataset will provide a path toward developing blood-based biomarkers of inflammasome activation. Overall, our study establishes tools to discover and detect inflammatory caspase substrates and functions, provides a workflow for designing antibody reagents to study cell signaling, and extends the growing evidence of biological cross talk between the apoptotic and inflammatory caspases.

Loss of Diel Circadian Clock Gene Cycling Is a Part of Grape Berry Ripening.

Diel cycles of gene expression are thought to adapt plants to 24-h changes in environmental conditions. The circadian clock contributes to this process, but less is known about circadian programs in developing reproductive organs. While model plants and controlled conditions have contributed greatly to our knowledge of circadian clock function, there is a need to better understand its role in crop plants under field conditions with fluctuating light and temperature. In this study, we investigated changes in the circadian clock during the development of grape berries of Vitis vinifera L. We found that the transcripts of circadian clock homologs had high-amplitude oscillations prior to, but not during, ripening. As ripening progressed, the amplitude and rhythmicity of the diel oscillations decreased until most transcripts tested had no significant fluctuation over the 24-h cycle. Despite this loss of rhythmicity, the majority of circadian clock genes investigated were expressed at or near their abundance at the nadir of their pre-ripening oscillation although the berries remained transcriptionally active. From this, it can be concluded that cycling of the canonical circadian clock appears unnecessary for berry ripening. Our data suggest that changes in circadian clock dynamics during reproductive organ development may have important functional consequences.

Long-term Trends in Infection-Related Mortality in Adults Treated With Maintenance Dialysis.

RATIONALE & OBJECTIVE: Infection is 1 of the top 3 causes of death in patients receiving maintenance dialysis. We evaluated the trends over time and risk factors for infection-related deaths among people receiving dialysis. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: We included all adults who began dialysis between 1980 and 2018 in Australia and New Zealand. EXPOSURE: Age, sex, dialysis modality, and dialysis era. OUTCOME: Infection-related death. ANALYTICAL APPROACH: Incidence was described and standardized mortality ratios (SMR) calculated for infection-related death. Fine-Gray subdistribution hazards models were fitted, with non-infection-related death and kidney transplantation treated as competing events. RESULTS: The study comprised 46,074 patients who received hemodialysis and 20,653 who were treated with peritoneal dialysis who were followed for 164,536 and 69,846 person-years, respectively. There were 38,463 deaths during the follow-up period, 12% of which were ascribed to infection. The overall rate of mortality from infection (per 10,000 person-years) was 185 and 232 for patients treated with hemodialysis and peritoneal dialysis, respectively. The rates were 184 and 219 for males and females, respectively; and 99, 181, 255, and 292 for patients aged 18-44, 45-64, 65-74, 75 years and over, respectively. The rates were 224 and 163 for those commencing dialysis in years 1980-2005 and 2006-2018, respectively. The overall SMR declined over time, from 37.1 (95% CI, 35.5-38.8) in years 1980-2005 to 19.3 (95% CI, 18.4-20.3) in years 2006-2018, consistent with the declining 5-year SMR trend (P<0.001). Infection-related mortality was associated with being female, older age, and Aboriginal and/or a Torres Strait Islander or Maori. LIMITATIONS: Mediation analyses defining the causal relationships between infection type and infection-related death could not be undertaken as disaggregating the data was not feasible. CONCLUSIONS: The excess risk of infection-related death in patients on dialysis has improved substantially over time but remains more than 20 times higher than in the general population.

Sex Disparity in Cause-Specific and All-Cause Mortality Among Incident Dialysis Patients.

RATIONALE & OBJECTIVE: Early mortality rates of female patients receiving dialysis have been, at times, observed to be higher than rates among male patients. The differences in cause-specific mortality between male and female incident dialysis patients with kidney failure are not well understood and were the focus of this study. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: Incident patients who had initiated dialysis in Australia and New Zealand in 1998-2018. EXPOSURE: Sex. OUTCOMES: Cause-specific and all-cause mortality while receiving dialysis, censored for kidney transplant. ANALYTICAL APPROACH: Adjusted cause-specific proportional hazards models, focusing on the first 5 years following initiation of dialysis. RESULTS: Among 53,414 patients (20,876 [39%] female) followed for a median period of 2.8 (IQR, 1.3-5.2) years, 27,137 (51%) died, with the predominant cause of death attributed to cardiovascular disease (18%), followed by dialysis withdrawal (16%). Compared with male patients, female patients were more likely to die in the first 5 years after dialysis initiation (adjusted hazard ratio [AHR], 1.08 [95% CI, 1.05-1.11]). Even though female patients experienced a lower risk of cardiovascular disease-related mortality (AHR, 0.93 [95% CI, 0.89-0.98]) than male patients, they experienced a greater risk of infection-related (AHR, 1.20 [95% CI, 1.10-1.32]) and dialysis withdrawal-related (AHR, 1.19 [95% CI, 1.13-1.26]) mortality. LIMITATIONS: Possibility of residual and unmeasured confounders. CONCLUSIONS: Compared with male patients, female patients had a higher risk of all-cause mortality in the first 5 years after dialysis initiation, a difference driven by higher rates of mortality from infections and dialysis withdrawals. These findings may inform the study of sex differences in mortality in other geographic settings.

Development of an 18F-labeled anti-human CD8 VHH for same-day immunoPET imaging.

PURPOSE: Cancer immunotherapies (CITs) have revolutionized the treatment of certain cancers, but many patients fail to respond or relapse from current therapies, prompting the need for new CIT agents. CD8+ T cells play a central role in the activity of many CITs, and thus, the rapid imaging of CD8+ cells could provide a critical biomarker for new CIT agents. However, existing 89Zr-labeled CD8 PET imaging reagents exhibit a long circulatory half-life and high radiation burden that limit potential applications such as same-day and longitudinal imaging. METHODS: To this end, we discovered and developed a 13-kDa single-domain antibody (VHH5v2) against human CD8 to enable high-quality, same-day imaging with a reduced radiation burden. To enable sensitive and rapid imaging, we employed a site-specific conjugation strategy to introduce an 18F radiolabel to the VHH. RESULTS: The anti-CD8 VHH, VHH5v2, demonstrated binding to a membrane distal epitope of human CD8 with a binding affinity (KD) of 500 pM. Subsequent imaging experiments in several xenografts that express varying levels of CD8 demonstrated rapid tumor uptake and fast clearance from the blood. High-quality images were obtained within 1 h post-injection and could quantitatively differentiate the tumor models based on CD8 expression level. CONCLUSION: Our work reveals the potential of this anti-human CD8 VHH [18F]F-VHH5v2 to enable rapid and specific imaging of CD8+ cells in the clinic.

Donors With a Prior History of Cancer: Factors of Non-Utilization of Kidneys for Transplantation.

Cancer transmission from deceased donors is an exceedingly rare but potentially fatal complication in transplant recipients. We aimed to quantify the likelihood of non-utilization of kidneys for transplantation from donors with a prior cancer history. We included all intended and actual deceased donors in Australia and New Zealand between 1989 and 2017. Association between prior cancer history and non-utilization of donor kidneys was examined using adjusted logistic regression. Of 9,485 deceased donors, 345 (4%) had a prior cancer history. Of 345 donors with a prior cancer history, 197 (57%) were utilized for transplantation. Donor characteristics of age, sex and comorbidities were similar between utilized and non-utilized donors with prior cancer. The time from cancer to organ donation was similar between utilized and non-utilized donors, irrespective of cancer subtypes. Donors with a prior cancer history were less likely to be utilized [adjusted OR (95% CI) 2.29 (1.68-3.13)] than donors without prior cancer. Of all actual donors, the adjusted OR for non-utilization among those with prior cancer was 2.36 (1.58-3.53). Non-melanoma skin cancer was the most frequent prior cancer type for utilized and non-utilized potential donors. Donors with prior cancers were less likely to be utilized for transplantation, with no discernible differences in cancer characteristics between utilized and non-utilized donors.

Hip Arthroplasty Outcomes in the Presence of Kidney Failure: A National Data Linkage Study.

BACKGROUND: Patients who have kidney failure are at higher risk of requiring total hip arthroplasty (THA) and are at higher risk of complications. This study compared the rate of revision surgery and mortality following THA between patients who have kidney failure receiving long term dialysis or who had a kidney transplant and those who did not have kidney failure. METHODS: A data linkage study was performed using data from 2 national registries: a registry of dialysis and kidney transplant patients and a registry of THA procedures. Both registries had coverage of almost all procedures or treatments in Australia. Data from September 1999 to December 2016 were used. Mortality and revision surgery were compared between patients receiving dialysis, those who had a functioning kidney transplant, and patients who did not have kidney failure using Cox and Fine-Gray (competing risk) regression models. A total of 383,478 primary THA procedures were identified as people receiving dialysis (n = 490), who had a functioning kidney transplant (n = 459), or who did not have kidney failure (n = 382,529). RESULTS: There was no significant difference in the overall rate of revision surgery between the groups (dialysis versus no kidney failure HR = 1.20; 95% CI 0.76, 1.88, transplant versus no kidney failure (hazard ratio) HR = 1.01; 95% (confidence interval) CI 0.66, 1.53). The risk for death after surgery was significantly higher in the dialysis group compared to both the functioning transplant group (HR = 3.44; 95%CI 1.58, 7.5), and in those without kidney failure (HR = 4.13; 95%CI 3.25, 5.25). CONCLUSION: The rate of mortality after THA in patients on dialysis is higher than in patients who have a functioning transplant or those who do not have kidney failure, but there is no early excess mortality to suggest a difference in this metric due to the surgery.

Mutations in PBP2 from ceftriaxone-resistant Neisseria gonorrhoeae alter the dynamics of the ß3-ß4 loop to favor a low-affinity drug-binding state.

Resistance to the extended-spectrum cephalosporin ceftriaxone in the pathogenic bacteria Neisseria gonorrhoeae is conferred by mutations in penicillin-binding protein 2 (PBP2), the lethal target of the antibiotic, but how these mutations exert their effect at the molecular level is unclear. Using solution NMR, X-ray crystallography, and isothermal titration calorimetry, we report that WT PBP2 exchanges dynamically between a low-affinity state with an extended ß3-ß4 loop conformation and a high-affinity state with an inward ß3-ß4 loop conformation. Histidine-514, which is located at the boundary of the ß4 strand, plays an important role during the exchange between these two conformational states. We also find that mutations present in PBP2 from H041, a ceftriaxone-resistant strain of N. gonorrhoeae, increase resistance to ceftriaxone by destabilizing the inward ß3-ß4 loop conformation or stabilizing the extended ß3-ß4 loop conformation to favor the low-affinity drug-binding state. These observations reveal a unique mechanism for ceftriaxone resistance, whereby mutations in PBP2 lower the proportion of target molecules in the high-affinity drug-binding state and thus reduce inhibition at lower drug concentrations.

Mortality After Home Hemodialysis Treatment Failure and Return to In-Center Hemodialysis.

RATIONALE & OBJECTIVE: Patients on home hemodialysis (HHD) may eventually return to in-center hemodialysis (ICHD) for clinical, technical, or psychosocial reasons. We studied the mortality of patients returning to ICHD after HHD, comparing it with the mortality experience among patients receiving HHD and patients receiving ICHD without prior treatment with HHD. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: All patients represented in the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) who commenced HD during 2005-2015 and were treated for >90 days. EXPOSURE: ICHD and/or HHD, and clinical characteristics at study entry. OUTCOME: Mortality and cause of death. ANALYTICAL APPROACH: A time-varying multivariate Cox proportional hazards analysis with shared frailty was implemented to explore the association between patient treatment states and mortality. Patients were censored at the time of transplantation or change in treatment modality to peritoneal dialysis. RESULTS: A total of 19,306 patients initiated HD and were treated for >90 days. The mean age of patients was 60.8 ± 15.4 (SD) years, 62% were male, and 49% had diabetes. After HHD treatment failure, adjusted mortality was increased compared with continued HHD at 0-30 days (HR, 3.93 [95% CI, 2.09-7.40]; P < 0.001), 30-90 days (HR, 3.34 [95% CI, 1.98-5.62]; P < 0.001), and >90 days (HR, 2.29 [95% CI, 1.84-2.85]; P < 0.001). LIMITATIONS: Covariates recorded at dialysis initiation, residual confounding underlying successful initiation of HHD treatment, and observational data lacking detail on cause of HHD treatment failure. CONCLUSIONS: HHD treatment failure is associated with a significant increase in mortality compared with continued HHD. This risk was present in both the early (first 30 days and 30-90 days) and late (>90 days) periods after HHD treatment failure. Further investigation into the specific causes of treatment failure and death may highlight specific high-risk patients.

Factors influencing fertility rates in Australian women receiving kidney replacement therapy: analysis of linked Australia and New Zealand Dialysis and Transplant Registry and perinatal data over 22 years.

BACKGROUND: Pregnancy in women receiving kidney replacement therapy (KRT) is uncommon, and trends and factors influencing fertility rates remain poorly defined. METHODS: The Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) was linked to mandatory perinatal data sets (all births from 1991 to 2013, ≥20 weeks' gestation) in four Australian jurisdictions. Overall, age- and era-specific fertility rates were calculated based on general and KRT population denominators. RESULTS: From 2 948 084 births, 248 babies were born to 168 mothers receiving KRT (37 babies born to 31 dialysed mothers; 211 babies born to 137 transplanted mothers). Substantial agreement between ANZDATA and perinatal data sets was observed for birth events and outcomes. Transplanted women had higher fertility rates than dialysed women in all analyses, with 21.4 live births/1000 women/year [95% confidence interval (CI) 18.6-24.6] in transplanted women, 5.8 (95% CI 4.1-8.1) in dialysed women and 61.9 (95% CI 61.8-62.0) in the non-KRT cohort. Fertility rates for dialysed women rose in recent years. After adjusting for maternal age and treatment modality, Caucasian women had higher fertility rates, while women with pre-existing diabetes, or transplanted women with exposure to KRT for ≤3.0 years had lower rates. As expected, transplanted women with a pre-conception estimated glomerular filtration rate (eGFR) of <45 mL/min/1.73 m2 or transplant-to-pregnancy interval of <1.0 year had lower fertility rates. Geographical location, socioeconomic status and primary disease (glomerulonephritis versus other) did not affect fertility rates. CONCLUSIONS: Reporting of births to ANZDATA is sufficiently accurate to justify ongoing data collection. Rising fertility rates in dialysed women may indicate permissive attitudes towards pregnancy. Treatment modality, ethnicity, diabetes, pre-conception eGFR, transplant-to-pregnancy interval and duration of KRT exposure were associated with fertility rates. These factors should be considered when counselling women with kidney disease about parenthood.

Temporal changes and risk factors for death from early withdrawal within 12 months of dialysis initiation-a cohort study.

BACKGROUND: Mortality risk is high soon after dialysis initiation in patients with kidney failure, and dialysis withdrawal is a major cause of early mortality, attributed to psychosocial or medical reasons. The temporal trends and risk factors associated with cause-specific early dialysis withdrawal within 12 months of dialysis initiation remain uncertain. METHODS: Using data from the Australia and New Zealand Dialysis and Transplant Registry, we examined the temporal trends and risk factors associated with mortality attributed to early psychosocial and medical withdrawals in incident adult dialysis patients in Australia between 2005 and 2018 using adjusted competing risk analyses. RESULTS: Of 32 274 incident dialysis patients, 3390 (11%) experienced death within 12 months post-dialysis initiation. Of these, 1225 (36%) were attributed to dialysis withdrawal, with 484 (14%) psychosocial withdrawals and 741 (22%) medical withdrawals. These patterns remained unchanged over the past two decades. Factors associated with increased risk of death from early psychosocial and medical withdrawals were older age, dialysis via central venous catheter, late referral and the presence of cerebrovascular disease; obesity and Asian ethnicity were associated with decreased risk. Risk factors associated with early psychosocial withdrawals were underweight and higher socioeconomic status. Presence of peripheral vascular disease, chronic lung disease and cancers were associated with early medical withdrawals. CONCLUSIONS: Death from dialysis withdrawal accounted for >30% of early deaths in kidney failure patients initiated on dialysis and remained unchanged over the past two decades. Several shared risk factors were observed between mortality attributed to early psychosocial and medical withdrawals.

Reductive Amination Revisited: Reduction of Aldimines with Trichlorosilane Catalyzed by Dimethylformamide─Functional Group Tolerance, Scope, and Limitations.

Aldimines, generated in situ from aliphatic, aromatic, and heteroaromatic aldehydes and aliphatic, aromatic, and heteroaromatic primary or secondary amines, can be reduced with trichlorosilane in the presence of dimethylformamide (DMF) as an organocatalyst (≤10 mol %) in toluene or CH2Cl2 at room temperature. The reduction tolerates ketone carbonyls, esters, amides, nitriles, sulfones, sulfonamides, NO2, SF5, and CF3 groups, boronic esters, azides, phosphine oxides, C═C and C≡C bonds, and ferrocenyl nucleus, but sulfoxides and N-oxides are reduced. α,ß-Unsaturated aldimines undergo 1,2-reduction only, leaving the C═C bond intact. N-Monoalkylation of primary amines is attained with a 1:1 aldehyde to amine ratio, whereas excess of the aldehyde (≥2:1) allows second alkylation, giving rise to tertiary amines. Reductive N-alkylation of α-amino acids proceeds without racemization; the resulting products, containing a C≡C bond or N3 group, are suitable for click chemistry. This reaction thus offers advantages over the traditional methods (borohydride reduction or catalytic hydrogenation) in terms of efficiency and chemoselectivity. Solubility of some of the reacting partners appears to be the only limitation. The byproducts generated by the workup with aqueous NaHCO3 (i.e., NaCl and silica) are environmentally benign. As a greener alternative, DMA can be employed as a catalyst instead of DMF.

Interactions Between Donor Age and 12-Month Estimated Glomerular Filtration Rate on Allograft and Patient Outcomes After Kidney Transplantation.

Reduced estimated glomerular filtration rate (eGFR) at 12-months after kidney transplantation is associated with increased risk of allograft loss, but it is uncertain whether donor age and types modify this relationship. Using Australia and New Zealand registry data, multivariable Cox proportional modelling was used to examine the interactive effects between donor age, types and 12-month eGFR on overall allograft loss. We included 11,095 recipients (4,423 received live-donors). Recipients with lowest 12-month eGFR (<30 ml/min/1.73 m2) experienced the greatest risk of allograft loss, with adjusted HR [95% CI) of 2.65 [2.38-2.95] compared to eGFR of 30-60 ml/min/1.73 m2; whereas the adjusted HR for highest eGFR (>60 ml/min/1.73 m2) was 0.67 [0.62-0.74]. The association of 12-month eGFR and allograft loss was modified by donor age (but not donor types) where a higher risk of allograft loss in recipients with lower compared with higher 12-month eGFR being most pronounced in the younger donor age groups (p < 0.01). Recipients with eGFR <30 ml/min/1.73 m2 12-months after transplantation experienced ≥2.5-fold increased risk of overall allograft loss compared to those with eGFR of >60 ml/min/1.73 m2, and the magnitude of the increased risk is most marked among recipients with younger donors. Careful deliberation of other factors including donor age when considering eGFR as a surrogate for clinical endpoints is warranted.

Mutations in penicillin-binding protein 2 from cephalosporin-resistant Neisseria gonorrhoeae hinder ceftriaxone acylation by restricting protein dynamics.

The global incidence of the sexually transmitted disease gonorrhea is expected to rise due to the spread of Neisseria gonorrhoeae strains with decreased susceptibility to extended-spectrum cephalosporins (ESCs). ESC resistance is conferred by mosaic variants of penicillin-binding protein 2 (PBP2) that have diminished capacity to form acylated adducts with cephalosporins. To elucidate the molecular mechanisms of ESC resistance, we conducted a biochemical and high-resolution structural analysis of PBP2 variants derived from the decreased-susceptibility N. gonorrhoeae strain 35/02 and ESC-resistant strain H041. Our data reveal that mutations both lower affinity of PBP2 for ceftriaxone and restrict conformational changes that normally accompany acylation. Specifically, we observe that a G545S substitution hinders rotation of the ß3 strand necessary to form the oxyanion hole for acylation and also traps ceftriaxone in a noncanonical configuration. In addition, F504L and N512Y substitutions appear to prevent bending of the ß3-ß4 loop that is required to contact the R1 group of ceftriaxone in the active site. Other mutations also appear to act by reducing flexibility in the protein. Overall, our findings reveal that restriction of protein dynamics in PBP2 underpins the ESC resistance of N. gonorrhoeae.