8 research outputs found
Investigation on MMACHC-R161Q pathological mutant from cblC disease
The cblC disease is a rare inborn disorder of the vitamin B12 (cobalamin, Cbl) metabolism characterized by combined methylmalonic aciduria and homocystinuria. The clinical consequences are devastating and, even when early treated with current therapies, the affected children manifest symptoms involving vision, growth, and learning. The molecular genetic cause of the disease was found in the mutations of the gene coding for MMACHC, a 282 amino acid protein that transports and processes the various forms of Cbl.
Here we present the biophysical characterization of wild type MMACHC and a variant, p.R161Q, resulting from the most common missense pathological mutation found in cblC patients.
By using a biophysical approach we investigated the stability of the two proteins and their ability to bind and transform the vitamin B12, and to assemble in a dimeric structure. Moreover, interesting indications about the behaviour of the proteins resulted from the Molecular Dynamics (MD) simulations.
Overall, our results reveal how a biophysical approach based on the complementarity of computational and experimental methods can offer new insights in the study of the specific effects of the pathological cblC mutation and help prospecting new routes for the cblC treatment
Structural Investigations of the Nickel-Induced Inhibition of Truncated Constructs of the JMJD2 Family of Histone Demethylases Using Xâray Absorption Spectroscopy
Occupational
and/or environmental exposure to nickel has been implicated
in various types of cancer, and <i>in vitro</i> exposure
to nickel compounds results in the accumulation of NiÂ(II) ions in
cells. One group of major targets of NiÂ(II) ions inside the cell consists
of FeÂ(II)- and αKG-dependent dioxygenases. Using JMJD2A and
JMJD2C as examples, we show that the JMJD2 family of histone demethylases,
which are products of putative oncogenes as well as FeÂ(II)- and αKG-dependent
dioxygenases, are highly sensitive to inhibition by NiÂ(II) ions. In
this work, X-ray absorption spectroscopy (XAS) has been used to investigate
the FeÂ(II) active site of truncated JMJD2A and JMJD2C (1â350
amino acids) in the presence and absence of αKG and/or substrate
to obtain mechanistic details of the early steps in catalysis that
precede O<sub>2</sub> binding in histone demethylation by the JMJD2
family of histone demethylases. Zinc K-edge XAS has been performed
on the resting JMJD2A (with iron in the active site) to confirm the
presence of the expected structural zinc site. XAS of the NiÂ(II)-substituted
enzymes has also been performed to investigate the inhibition of these
enzymes by NiÂ(II) ions. Our XAS results indicate that the five-coordinate
FeÂ(II) center in the resting enzyme is retained in the binary and
ternary complexes. In contrast, the NiÂ(II) center is six-coordinate
in the resting enzyme and binary and ternary complexes. XAS results
indicate that both FeÂ(II) and NiÂ(II) bind αKG in the binary
and ternary complexes. The electron density buildup that is observed
at the FeÂ(II) center in the presence of αKG and substrate is
not observed at the NiÂ(II) center. Thus, both electronic and steric
factors are responsible for Ni-induced inhibition of the JMJD2 family
of histone demethylases. Ni-induced inhibition of these enzymes may
explain the alteration of the epigenetic mechanism of gene expression
that is responsible for Ni-induced carcinogenesis
Gene expression changes in human lung cells exposed to arsenic, chromium, nickel or vanadium indicate the first steps in cancer
Developmental methoxychlor exposure affects multiple reproductive parameters and ovarian folliculogenesis and gene expression in adult rats
Morphological alterations in the liver of yellow perch (Perca flavescens) from a biological mercury hotspot
Structural Investigations of the Nickel-Induced Inhibition of Truncated Constructs of the JMJD2 Family of Histone Demethylases Using X-ray Absorption Spectroscopy
Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries
Background
Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks.
Methods
The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned.
Results
A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31).
Conclusion
Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)