The silent mutational landscape of infant MLL-AF4 pro-B acute lymphoblastic leukemia

Over 90% of infants (< 1-year-old) diagnosed with leukemia have pro-B acute lymphoblastic leukemia (ALL) containing the MLL-AF4 fusion. When compared with other forms of paediatric ALL affecting later B-cell differentiation, MLL-AF4 pro-B is associated with a dismal prognosis with a typical 5-year disease-free survival of <20%. MLL-AF4 may be sufficient on its own for leukemogenesis or the gene-fusion product may alternatively predispose transformed cells to global genetic instability, enhancing the acquisition of additional key mutations. To gain insight into the genomic landscape of infant MLL-AF4 pro-B ALL we performed whole genome sequencing of diagnostic leukemic blasts and matched germline samples from three MLL-AF4 pro-B ALL infants. Our analysis revealed few somatic changes (copy number abnormalities, loss of heterozygosity, or single nucleotide variants), demonstrating that only a very small number of mutations are necessary to generate infant MLL-leukemia.

The CCND1 c.870G>A polymorphism is a risk factor for t(11;14)(q13;q32) multiple myeloma

A number of specific chromosomal abnormalities define the subgroups of multiple myeloma. In a meta-analysis of two genome-wide association studies of multiple myeloma including a total of 1,661 affected individuals, we investigated risk for developing a specific tumor karyotype. The t(11;14)(q13;q32) translocation in which CCND1 is placed under the control of the immunoglobulin heavy chain enhancer was strongly associated with the CCND1 c.870G>A polymorphism (P = 7.96 × 10(-11)). These results provide a model in which a constitutive genetic factor is associated with risk of a specific chromosomal translocation.

Germline mutations affecting the proofreading domains of POLE and POLD1 predispose to colorectal adenomas and carcinomas

Many individuals with multiple or large colorectal adenomas or early-onset colorectal cancer (CRC) have no detectable germline mutations in the known cancer predisposition genes. Using whole-genome sequencing, supplemented by linkage and association analysis, we identified specific heterozygous POLE or POLD1 germline variants in several multiple-adenoma and/or CRC cases but in no controls. The variants associated with susceptibility, POLE p.Leu424Val and POLD1 p.Ser478Asn, have high penetrance, and POLD1 mutation was also associated with endometrial cancer predisposition. The mutations map to equivalent sites in the proofreading (exonuclease) domain of DNA polymerases ɛ and δ and are predicted to cause a defect in the correction of mispaired bases inserted during DNA replication. In agreement with this prediction, the tumors from mutation carriers were microsatellite stable but tended to acquire base substitution mutations, as confirmed by yeast functional assays. Further analysis of published data showed that the recently described group of hypermutant, microsatellite-stable CRCs is likely to be caused by somatic POLE mutations affecting the exonuclease domain.

Technology-assisted and sutureless microvascular anastomoses: evidence for current techniques

BACKGROUND

Since the birth of reconstructive microvascular surgery, attempts have been made to shorten the operative time while maintaining patency and efficacy. Several devices have been developed to aid microsurgical anastomoses. This article investigates each of the currently available technologies and attempts to provide objective evidence supporting their use.

METHODS

Techniques of microvascular anastomosis were investigated by performing searches of the online databases Medline and Pubmed. Returned results were assessed according to the criteria for ranking medical evidence advocated by the Oxford Centre for Evidence Based Medicine. Emphasis was placed on publications with quantifiable endpoints such as unplanned return to theatre, flap salvage, and complication rates.

RESULTS

There is a relative paucity of high-level evidence supporting any form of assisted microvascular anastomosis. Specifically, there are no randomized prospective trials comparing outcomes using one method versus any other. However, comparative retrospective cohort studies do exist and have demonstrated convincing advantages of certain techniques. In particular, the Unilink™/3M™ coupler and the Autosuture™ Vessel Closure System® (VCS®) clip applicator have been shown to have level 2b evidence supporting their use, meaning that the body of evidence achieves a level of comparative cohort studies.

CONCLUSION

Of the available forms of assisted microvascular anastomoses, there is level 2b evidence suggesting a positive outcome with the use of the Unilink™/3M™ coupler and the Autosuture™ VCS® clip applicator. Other techniques such as cyanoacrylates, fibrin glues, the Medtronic™ U-Clip®, and laser bonding have low levels of evidence supporting their use. Further research is required to establish any role for these techniques.

Common variation at 3p22.1 and 7p15.3 influences multiple myeloma risk

To identify risk variants for multiple myeloma, we conducted a genome-wide association study of 1,675 individuals with multiple myeloma and 5,903 control subjects. We identified risk loci for multiple myeloma at 3p22.1 (rs1052501 in ULK4; odds ratio (OR) = 1.32; P = 7.47 × 10(-9)) and 7p15.3 (rs4487645, OR = 1.38; P = 3.33 × 10(-15)). In addition, we observed a promising association at 2p23.3 (rs6746082, OR = 1.29; P = 1.22 × 10(-7)). Our study identifies new genomic regions associated with multiple myeloma risk that may lead to new etiological insights.

Computed tomographic angiography: clinical applications

There has been a move towards increasingly refined techniques for autologous breast reconstruction, and given the substantial inter-individual variability of perforator anatomy, the need for reliable, accurate methods of vascular imaging has been sought. Computed tomographic angiography (CTA) can offer a range of applications in autologous breast reconstruction to aid surgical planning and improved outcomes. This article explores the utility of CTA in imaging perforators, pedicles and recipient vessels across a wide range of flap types and donor sites. CTA has a range of clinical applications in autologous breast reconstruction, and can aid operative planning and improve outcomes.

The importance of the superficial venous anatomy of the abdominal wall in planning a superficial inferior epigastric artery (SIEA) flap: case report and clinical study

The importance of the venous drainage of the anterior abdominal wall to free tissue transfer in deep inferior epigastric artery perforator flap surgery has been highlighted in several recent publications in this journal, however the same attention has not been given to superficial inferior epigastric artery (SIEA) flaps, in which the flap necessarily relies on the superficial venous drainage. We describe a unique case, in which the presence of two superficial inferior epigastric veins (SIEVs) draining into separate venous trunks was identified. The use of only one trunk led to a well-demarcated zone of venous congestion. A clinical study was also conducted, assessing 200 hemiabdominal walls with preoperative computed tomographic angiography imaging. The presence of more than a single major SIEV trunk was present in 80 hemiabdominal walls (40% of overall sides). There was considerable variability in the source of drainage of the SIEV, draining variably into the deep inferior epigastric vein, the great saphenous vein, the saphenous bulb, a common trunk with the superficial circumflex iliac vein or a common trunk with a second branch of the SIEV. These findings highlight the considerable variation in the number of SIEV trunks as well as their source of regional drainage, and show the importance of consideration of such variation.

The variability of the Superficial Inferior Epigastric Artery (SIEA) and its angiosome: A clinical anatomical study

INTRODUCTION

The superficial inferior epigastric artery (SIEA) is a useful pedicle in supply to the lower abdominal integument, with its use sparing damage to rectus abdominis muscle or sheath. However, it is limited in usefulness due to its anatomical variability. While previous anatomical studies have been limited in number and study design, the use of preoperative imaging has enabled the analysis of this vasculature in large numbers and greater anatomical detail.

METHODS

A clinical anatomical study of 500 hemi-abdominal walls in 250 consecutive patients undergoing preoperative computed tomographic angiography (CTA) prior to autologous breast reconstruction was undertaken. The presence, size, location, and branching pattern of the SIEA were assessed in each case.

RESULTS

The SIEA was identified in 468 cases, an incidence of 94%. Its mean diameter was 0.6 mm, and in 24% of cases was of a diameter >1.5 mm. SIEA location was highly variable, with mean position 2-cm lateral to the linea semilunaris (range 0-8 cm lateral), and relationship to the superficial inferior epigastric vein (SIEV) was also highly variable, with the distance between them ranging from 0.3 to 8.5 cm apart. SIEA branches directly crossed the abdominal midline in 5% of cases. Larger SIEA diameters correlated with a decrease in diameter of ipsilateral DIEA perforators.

CONCLUSION

The SIEA is present more frequently than previously demonstrated, but is typically too small for use in free tissue transfer. The variable degree of SIEA branching suggests that its territory of supply is also variable, and that preoperative imaging may be useful in planning SIEA flaps.

Sequencing delivers diminishing returns for homology detection: implications for mapping the protein universe

MOTIVATION

Databases of sequenced genomes are widely used to characterize the structure, function and evolutionary relationships of proteins. The ability to discern such relationships is widely expected to grow as sequencing projects provide novel information, bridging gaps in our map of the protein universe.

RESULTS

We have plotted our progress in protein sequencing over the last two decades and found that the rate of novel sequence discovery is in a sustained period of decline. Consequently, PSI-BLAST, the most widely used method to detect remote evolutionary relationships, which relies upon the accumulation of novel sequence data, is now showing a plateau in performance. We interpret this trend as signalling our approach to a representative map of the protein universe and discuss its implications.

The efficacy of postoperative monitoring: a single surgeon comparison of clinical monitoring and the implantable Doppler probe in 547 consecutive free flaps

BACKGROUND

An important element in achieving high success rates with free flap surgery has been the use of different techniques for monitoring flaps postoperatively as a means to detecting vascular compromise. Successful monitoring of the vascular pedicle to a flap can potentiate rapid return to theater in the setting of compromise, with the potential to salvage the flap. There is little evidence that any technique offers any advantage over clinical monitoring alone.

METHODS

A consecutive series of 547 patients from a single plastic surgical unit who underwent a fasciocutaneous free flap operation for breast reconstruction [deep inferior epigastric artery perforator (DIEP) flap, superficial inferior epigastric artery (SIEA) flap, or superior gluteal artery perforator (SGAP) flap] were included. A comparison was made between the first 426 consecutive patients in whom flap monitoring was performed using clinical monitoring alone and the subsequent 121 patients in whom monitoring was achieved with the Cook-Swartz implantable Doppler probe. Outcome measures included flap salvage rate and false-positive rate.

RESULTS

There was a strong trend toward improved salvage rates with the implantable Doppler probe compared with clinical monitoring (80% vs. 66%, P = 0.48). When combined with the literature (meta-analysis), the data prove statistically significant (P < 0.01). There was no statistical difference between the groups for false-positive rates.

CONCLUSION

Flap monitoring with the implantable Doppler probe can improve flap salvage rates without increasing the rate of false-positive takebacks.

Postoperative monitoring of free flaps in autologous breast reconstruction: a multicenter comparison of 398 flaps using clinical monitoring, microdialysis, and the implantable Doppler probe

Many techniques for flap monitoring following free tissue transfer have been described; however, there is little evidence that any of these techniques allow for greater rates of flap salvage over clinical monitoring alone. We sought to compare three established monitoring techniques across three experienced microsurgical centers in a comparable cohort of patients. A retrospective, matched cohort study of 398 consecutive free flaps in 347 patients undergoing autologous breast reconstruction was undertaken across three institutions during the same 3-year period, with a single form of postoperative monitoring used at each institution: clinical monitoring alone, the Cook-Swartz implantable Doppler probe, or microdialysis. Both objective and subjective measures of efficacy were assessed. Clinical monitoring alone, the implantable Doppler probe, and microdialysis showed statistically similar rates of flap salvage. False-negative rates were also statistically similar (only seen in the clinically monitored group). However, there was a statistically significant increase in false-positive alarms causing needless take-backs to theater in the microdialysis and implantable Doppler arms, P < 0.001. This study did not find any technique superior to clinical monitoring alone. New monitoring technologies should be compared objectively with clinical monitoring as the current standard in postoperative flap monitoring.

Evaluating anatomical research in surgery: a prospective comparison of cadaveric and living anatomical studies of the abdominal wall

BACKGROUND

Cadaveric research has widely influenced our understanding of clinical anatomy. However, while many soft-tissue structures remain quiescent after death, other tissues, such as viscera, undergo structural and functional changes that may influence their use in predicting living anatomy. In particular, our understanding of vascular anatomy has been based upon cadaveric studies, in which vascular tone and flow do not match the living situation.

METHODS

An angiographic analysis of the abdominal wall vasculature was performed using plain film and computed tomography angiography in 60 cadaveric hemi-abdominal walls (from 31 cadavers) and 140 living hemi-abdominal walls (in 70 patients). The deep inferior epigastric artery (DIEA) and all of its perforating branches larger than 0.5 mm were analysed for number, calibre and location.

RESULTS

Both large, named vessels and small calibre vessels show marked differences between living anatomy and cadaveric specimens. The DIEA was of larger diameter (4.2 mm versus 3.1 mm, P < 0.01) and had more detectable branches in the cadaveric specimens. Perforators were of greater calibre (diameter 1.5 mm versus 0.8 mm, P < 0.01) and were more plentiful (16 versus 6, P < 0.01) in cadaveric specimens. However, the location of individual vessels was similar.

CONCLUSIONS

Cadaveric anatomy displays marked differences to in vivo anatomy, with the absence of living vascular dynamics affecting vessel diameters in cadaveric specimens. Blood vessels are of greater measurable calibre in cadaveric specimens than in the living. Consequently, cadaveric anatomy should be interpreted with consideration of post-mortem changes, while living anatomical studies, particularly with the use of imaging technologies, should be embraced in anatomical research.