Early risk prognosis of free-flap transplant failure by quantitation of the macrophage colony-stimulating factor in patient plasma using 2-dimensional liquid-chromatography multiple reaction monitoring-mass spectrometry.

Although great success of microvascular free-flap transplantation surgery has been achieved in recent years, between 1.5% and 15% of flaps are still lost due to vascular occlusion. The clinical challenge remains to salvage a transplant in the case of vascular complications. Since flap loss is devastating for the patient, it is of utmost importance to detect signs of complications or of conspicuities as soon as possible. Rescue success rates highly depend on early revision. In this study, we collected blood samples during transplantation surgery from either the contributory artery or the effluent vein of the flap and applied a targeted mass spectrometry-based approach to quantify 24 acute phase proteins, cytokines, and growth factors in 63 plasma samples from 21 hospitalized patients, generating a dataset with 9450 protein concentration values. Biostatistical analyses of the targeted plasma protein concentrations in all 63 plasma samples showed that venous concentrations of macrophage colony-stimulating factor (M-CSF) provided the highest accuracy for discriminating patients with either clinical conspicuities or complications from control individuals. Using 21.33 ng/mL of M-CSF as the diagnostic threshold when analyzing venous blood plasma samples, the assay obtained a sensitivity of 0.93 and a specificity of 0.85 with an area under the curve value of 0.902 in the receiver operating characteristic analysis. Overall, our results indicate that M-CSF is a potential molecular marker for early risk prognosis of free-flap transplant failure.

Mass spectrometric characterization of limited proteolysis activity in human plasma samples under mild acidic conditions.

We developed a limited proteolysis assay for estimating dynamics in plasma-borne protease activities using MALDI ToF MS analysis as readout. A highly specific limited proteolysis activity was elicited in human plasma by shifting the pH to 6. Mass spectrometry showed that two singly charged ion signals at m/z 2753.44 and m/z 2937.56 significantly increased in abundance under mild acidic conditions as a function of incubation time. For proving that a provoked proteolytic activity in mild acidic solution caused the appearance of the observed peptides, control measurements were performed (i) with pepstatin as protease inhibitor, (ii) with heat-denatured samples, (iii) at pH 1.7, and (iv) at pH 7.5. Mass spectrometric fragmentation analysis showed that the observed peptides encompass the amino acid sequences 1-24 and 1-26 from the N-terminus of human serum albumin. Investigations on peptidase specificities suggest that the two best candidates for the observed serum albumin cleavages are cathepsin D and E. Reproducibility, robustness, and sensitivity prove the potential of the developed limited proteolysis assay to become of clinical importance for estimating dynamics of plasma-borne proteases with respect to associated pathophysiological tissue conditions.

Long-term follow-up of donor site morbidity after defect coverage with Integra following radial forearm flap elevation.

BACKGROUND: The radial forearm flap (RFF) is known for its excellent and reliable results regarding defect coverage though donor site morbidity represents a persisting problem. Integra is widely used in reconstructive surgery. This study aims to assess long-term outcomes regarding functionality and cosmesis after donor site coverage with respect to esthetic appearance, scar quality, and wrist function as well as ability to work after donor site coverage with Integra and split-thickness skin. METHODS: The prospective follow-up exam, after a mean time of 23.8 months, enrolled 13 patients. Identification of patients' comorbidities and evaluation of the subjective esthetic outcome, sensibility, cold intolerance, and scar instability was assessed by a questionnaire. In clinics, designed Pinch test assessed scar tissue mobility over the flexor tendons. The Vancouver Scar Scale (VSS) was calculated; wrist function and grip strength were determined. RESULTS: The satisfaction score for the esthetic appearance of the donor site was in average 3.42 ± 0.44. Two patients experienced an unstable scar and cold intolerance. The VSS resulted in a value of 4.2 representing a good result. The pinch test revealed an average scar mobility of 8 mm without any tendon adhesions. Active range of motion of the wrist was equal to the non-operated site as was grip strength. The pinch test showed a significant negative correlation with the VSS making it a reliable tool to measure scar quality. CONCLUSION: Long-term results show an esthetic and functional successful defect coverage of the RFF donor site by the use of Integra and split-thickness skin. Level of Evidence: Level IV, therapeutic study.