The osteocutaneous free fibula flap: is the skin paddle reliable?

This clinical and anatomic study was undertaken to see if the skin paddle of the osteocutaneous fibula flap could be made more reliable. Eighty cadaver limbs were dissected to evaluate the type, number, and location of the cutaneous perforators supplying the lateral leg. Three types of perforators were identified: septocutaneous, musculocutaneous, and a type we termed septomuscular, which does not actually run within the muscle substance but is adherent to the muscle. Although not a true musculocutaneous perforator, it should be treated as such clinically. Musculocutaneous perforators were found to be more numerous and more proximal than the septocutaneous perforators. Eighteen clinical cases demonstrate a 33 percent skin paddle survival when dissected as a septocutaneous flap and a 93 percent skin paddle survival when dissected as a septomusculocutaneous flap. In using the osteocutaneous fibula flap, it is recommended that a cuff of soleus and flexor hallucis longus be incorporated into the flap to help ensure flap viability.     

Breast reconstruction with the DIEP flap or the muscle-sparing (MS-2) free TRAM flap: is there a difference?

The advantages of breast reconstruction using the deep inferior epigastric perforator (DIEP) flap and the muscle-sparing free transverse rectus abdominis musculocutaneous (TRAM) flap (MS-2) are well recognized. Both techniques optimize abdominal function by maintaining the vascularity, innervation, and continuity of the rectus abdominis muscle. The purpose of this study was to compare these two methods of breast reconstruction and determine whether there is a difference in outcome. The study considered 177 women who have had breast reconstruction using muscle-sparing flaps over a 4-year period. This includes 89 women who had an MS-2 free TRAM flap procedure, of which 65 were unilateral and 24 were bilateral, and 88 women who had a DIEP flap procedure, of which 66 were unilateral and 22 were bilateral. The total number of flaps was 223. Mean follow-up was 23 months (range, 3 to 49 months). For all MS-2 free TRAM flaps (n = 113), outcome included fat necrosis in eight (7.1 percent), venous congestion in three (2.7 percent), and total necrosis in two (1.8 percent). For the women who had an MS-2 free TRAM flap, an abdominal bulge occurred in three women (4.6 percent) after unilateral reconstruction and in five women (21 percent) after bilateral reconstruction. The ability to perform sit-ups was noted in 63 women (97 percent) after unilateral reconstruction and 20 women (83 percent) after bilateral reconstruction. For all DIEP flaps (n = 110), outcome included fat necrosis in seven (6.4 percent), venous congestion in five (4.5 percent), and total necrosis in three (2.7 percent) patients. For the women who had DIEP flap reconstruction, an abdominal bulge occurred in one woman (1.5 percent) after unilateral reconstruction and in one woman (4.5 percent) after bilateral reconstruction. The ability to perform sit-ups was noted in all women after unilateral reconstruction and in 21 women (95 percent) after bilateral reconstruction. These results demonstrate that there are no significant differences in fat necrosis, venous congestion, or flap necrosis after DIEP or MS-2 free TRAM flap reconstruction. The percentage of women who are able to perform sit-ups and the percentage of women who did not develop a postoperative abdominal bulge is increased after DIEP flap reconstruction; however, this difference is not statistically significant.     

Personalizing foods: is genotype necessary?

The inescapable conclusion of a just a decade of nutrigenomics research must now be brought to practice. Humans differ in their responses to diet and many of these differences are being assigned to genetic polymorphisms. However, differences in the varying responses to diet between humans are not solely because of genetic variation. Lifestage, lifestyle, prior nutritional and physiological variables and even your mother's microflora all influence the differences between humans. The question becomes: are all of these inputs to an individual's health measurable as part of a nutritional phenotype assessment? The answer to this question is increasingly, yes. As variations in humans can be both measured and even more importantly understood, the implications of those measures to dietary guidance become actionable. More accurate assessment of the inputs to human health and the consequences of those inputs measured as accurate proteomic and metabolomic analyses would bring personalized health to practice far faster than waiting for a predictive knowledge of genetic variation.     

Walking on a ‘peg leg’: extensor muscle activities and sensory feedback after distal leg denervation in cockroaches

Previous studies in insects demonstrated that leg coordination changes following complete ablation of distal limb segments. However, normal coordination was restored when small peg leg prostheses were attached to leg stumps to permit substrate contact. We have adapted this paradigm to preserve appropriate leg mass and inertia by severing all nerves and muscle tendons in the femur of the cockroach hind leg and converting the animals own limb into a peg leg. Recordings of muscle activities and leg movements before and after denervation showed that: (1) the peg leg is actively used in walking and regular bursts occur in motoneurons to leg extensor muscles; (2) driving of motoneuron activity is sufficient to produce fictive bursting in a muscle whose tendon (apodeme) is cut in the ablation; and (3) similar motoneuron activities are found in walking on an oiled glass surface, when the effects of body weight and mechanical coupling are minimized. When distal segments were completely severed in these preparations, leg use and muscle bursting were disrupted but could be restored if the stumps were pressed against the substrate. These results support the hypothesis that feedback from receptors in proximal leg segments indicating forces allows for active leg use in walking.     

Intramuscular triacylglycerol utilization in human skeletal muscle during exercise: is there a controversy?

Intramuscular triacylglyerols (IMTGs) represent a potentially important energy source for contracting human skeletal muscle. Although the majority of evidence from isotope tracer and (1)H-magnetic resonance spectroscopy (MRS) studies demonstrate IMTG utilization during exercise, controversy regarding the importance of IMTG as a metabolic substrate persists. The controversy stems from studies that measure IMTG in skeletal muscle biopsy samples and report no significant net IMTG degradation during prolonged moderate-intensity (55-70% maximal O(2) consumption) exercise lasting 90-120 min. Although postexercise decrements in IMTG levels are often reported from direct muscle measurements, the marked between-biopsy variability (approximately 23%) that has been reported with this technique in untrained subjects is larger than the expected decrease in IMTG content, effectively precluding significant findings. In contrast, recent data obtained in endurance-trained subjects demonstrated reduced variability between duplicate biopsies (approximately 12%), and significant changes in IMTG were detected after 120 min of moderate-intensity exercise. Therefore, it is our contention that the muscle biopsy, isotope tracer, and (1)H-MRS techniques report significant and energetically important oxidation of free fatty acids derived from IMTGs during prolonged moderate exercise.     

Natural alcohol exposure: is ethanol the main substrate for alcohol dehydrogenases in animals?

Alcohol dehydrogenase (ADH) activity is widely distributed in all phyla. In animals, three non-homologous NAD(P)(+)-dependent ADH protein families are reported. These arose independently throughout evolution and possess different structures and mechanisms of reaction: type I (medium-chain) ADHs are zinc-containing enzymes and comprise the most studied group in vertebrates; type II (short-chain) ADHs lack metal cofactor and have been extensively studied in Drosophila; and type III ADHs are iron-dependent/-activated enzymes that were initially identified only in microorganisms. The presence of these different ADHs in animals has been assumed to be a consequence of chronic exposure to ethanol. By far the most common natural source of ethanol is fermentation of fruit sugars by yeast, and available data support that this fruit trait evolved in concert with the characteristics of their frugivorous seed dispersers. Therefore, if the presence of ADHs in animals evolved as an adaptive response to dietary ethanol exposure, then it can be expected that the enzymogenesis of these enzymes began after the appearance of angiosperms with fleshy fruits, because substrate availability must precede enzyme selection. In this work, available evidence supporting this possibility is discussed. Phylogenetic analyses reveal that type II ADHs suffered several duplications, all of these restricted to flies (order Diptera). Induction of type II Adh by ethanol exposure, a positive correlation between ADH activity and ethanol resistance, and the fact that flies and type II Adh diversification occurred in concert with angiosperm diversification, strongly suggest that type II ADHs were recruited to allow larval flies to exploit new restricted niches with high ethanol content. In contrast, phyletic distribution of types I and III ADHs in animals showed that these appeared before angiosperms and land plants, independently of ethanol availability. Because these enzymes are not induced by ethanol exposure and possess a high affinity and/or catalytic efficiency for non-ethanol endogenous substrates, it can be concluded that the participation of types I and III ADHs in ethanol metabolism can be considered as incidental, and not adaptive.     

The continuing HIV vaccine saga: is a paradigm shift necessary?

As pointed out in previous editorials, the development of an effective vaccine for the Human Immunodeficiency Virus capable of preventing infection, or even one capable of preventing the Acquired Immunodeficiency Disease Syndrome, has eluded investigators for the past 20 years. Now Reche and Keskin and their co-workers have provided evidence that an entirely new approach, based upon modern bioinformatics methods and skillful in vitro immunological experiments, may result in an effective way to prime the T cell immune response of normal individuals against conserved peptide epitopes.