The effect of sarcopenic obesity and muscle quality on complications after DIEP-flap breast reconstruction

Introduction: The aim of this study was to evaluate whether sarcopenic obesity and muscle quality as expressed by skeletal muscle radiodensity (SMD) are associated to postoperative complications in women undergoing DIEP-flap breast reconstruction (BR). Methods: All patients who underwent DIEP-flap BR at our tertiary center between 2010 and 2018 were asked to sign informed consent for the use of their electronic medical records and images. By outlining anatomical skeletal muscle contours on the preoperative abdominal CT-scan at lumbar level L3, SMD and skeletal muscle indices (SMI) were measured by two observers independently. Using logistic regression analyses, the association between sarcopenic obesity (BMI >25 & SMI <39), low SMD (<40HU), and Clavien-Dindo (CD) grade ≥ II complications was evaluated. In this way odds ratios (OR) and adjusted odds ratios (ORadjusted) were provided. Results: Out of the 103 patients included in this study, 36% had CD grade ≥ II complications within 30 days of surgery. Twenty patients (19%) suffered from sarcopenic obesity of whom eleven patients (55%) had CD grade ≥ II complications (OR = 2.7, p = 0.05). In a multivariate analysis, sarcopenic obesity was not significantly related to a higher complication rate (ORadjusted = 2.2, p = 0.14) but women with SMD below average and those with prior radiotherapy had a higher risk for grade ≥ II complications (ORadjusted = 2.9, p = 0.02 and ORadjusted = 2.7, p = 0.02 respectively). Conclusion: Below average SMD (<40HU) was found to be associated with the development of postoperative CD grade ≥ II complications in women undergoing DIEP-flap BR. Future research should evaluate whether improving SMD reduces the complication incidence in this patient group

C1 compounds as auxiliary substrate for engineered Pseudomonas putida S12

The solvent-tolerant bacterium Pseudomonas putida S12 was engineered to efficiently utilize the C1 compounds methanol and formaldehyde as auxiliary substrate. The hps and phi genes of Bacillus brevis, encoding two key steps of the ribulose monophosphate (RuMP) pathway, were introduced to construct a pathway for the metabolism of the toxic methanol oxidation intermediate formaldehyde. This approach resulted in a remarkably increased biomass yield on the primary substrate glucose when cultured in C-limited chemostats fed with a mixture of glucose and formaldehyde. With increasing relative formaldehyde feed concentrations, the biomass yield increased from 35% (C-mol biomass/C-mol glucose) without formaldehyde to 91% at 60% relative formaldehyde concentration. The RuMP-pathway expressing strain was also capable of growing to higher relative formaldehyde concentrations than the control strain. The presence of an endogenous methanol oxidizing enzyme activity in P. putida S12 allowed the replacement of formaldehyde with the less toxic methanol, resulting in an 84% (C-mol/C-mol) biomass yield. Thus, by introducing two enzymes of the RuMP pathway, co-utilization of the cheap and renewable substrate methanol was achieved, making an important contribution to the efficient use of P. putida S12 as a bioconversion platform host

Characterization of Cg10062 from Corynebacterium glutamicum: Implications for the Evolution of cis-3-Chloroacrylic Acid Dehalogenase Activity in the Tautomerase Superfamily†

A 149-amino acid protein designated Cg10062 is encoded by a gene from Corynebacterium glutamicum. The physiological function of Cg10062 is unknown, and the gene encoding this protein has no obvious genomic context. Sequence analysis links Cg10062 to the cis-3-chloroacrylic acid dehalogenase (cis-CaaD) family, one of the five known families of the tautomerase superfamily. The characterized tautomerase superfamily members have two distinctive characteristics: a P-cc-p structure motif and a catalytic amino-terminal proline. Pro-1 is present in the Cg10062 amino acid sequence along with His-28, Arg-70, Arg-73, Tyr-103, and Glu-114, all of which have been implicated as critical residues for cis-CaaD activity. The gene for Cg10062 has been cloned and the protein overproduced, purified, and subjected to kinetic and mechanistic characterization. Like cis-CaaD, Cg10062 functions as a hydratase: it converts 2-oxo-3-pentynoate to acetopyruvate and processes 3-bromopropiolate to a species that inactivates the enzyme by acylation of Pro-1. Kinetic and (1)H NMR spectroscopic studies also show that Cg10062 processes both isomers of 3-chloroacrylic acid at low levels with a clear preference for the cis isomer. Pro-1 is critical for the dehalogenase and hydratase activities because the PIA mutant no longer catalyzes either reaction. The presence of the six key catalytic residues and the hydratase activity coupled with the absence of an efficient cis-CaaD activity and the lack of isomer specificity implicate factors beyond this core set of residues in cis-CaaD catalysis and specificity. This work sets the stage for in-depth mechanistic and structural studies of Cg10062, which could identify the additional features necessary for a fully active and highly specific cis-CaaD. Such results will also shed light on how cis-CaaD emerged in the tautomerase superfamily because Cg10062 could be characteristic of an intermediate along the evolutionary pathway for this dehalogenase