A cadaveric study of the anatomical variation of the origins of the celiac trunk and the superior mesenteric artery: a role in median arcuate ligament syndrome?

Gray's Anatomy states, "the celiac trunk is the first anterior branch of the abdominal aorta and arises just below the aortic hiatus. The superior mesenteric artery originates from the aorta c1.0 cm below the celiac trunk." (Standring, 2008a, Gray's Anatomy. 40th Ed. London: Churchill Livingstone Elsevier, p. 1073-1074). During dissection classes with medical students we found this not to be the case. We have re-evaluated the anatomy of the origins of the celiac trunk (CT) and superior mesenteric artery (SMA) and the relationship of the CT to the median arcuate ligament (MAL) in 99 cadavers. We have found the external distance between the CT and SMA to range from 0 to 20 mm (mean 3.4 mm, SD 5.17 mm), with the two in direct apposition in 57.6% (n = 99) of cases: a higher figure than previously documented. However, the internal distance between the CT and SMA ranged from 10 to 30 mm (mean 18.9 mm, SD 4.09 mm). There was no distance measurable between the MAL and the CT in 88 cadavers (92.6%, n = 95) and, of these, 32 (33.7%) showed evidence of compression or kinking of the CT. We suspect that the MAL is responsible for the approximation of the CT to the SMA in these cadavers, and that the high incidence of kinking of the CT (33.7% of cases) may have implications with regard to its role in MAL syndrome.

The surgical anatomy of the radial nerve and the triceps aponeurosis.

The radial nerve passes around the posterior aspect of the humerus where it is prone to injury in both humeral fractures and surgical exploration of this region. We examined 55 cadaveric limbs to determine whether the exact position of the radial nerve could be reliably predicted on the basis of superficial anatomical markings. We found that when there is considerable variability in the position of the nerve in relation to the lateral epicondyle, the nerve consistently passed adjacent to the lateral border of the triceps aponeurosis at a distance of 22-27 (+/-2) mm. It was never found to be closer than 13 (+/-1) mm to the aponeurosis. The lateral border of the triceps aponeurosis is easy to identify and our findings may help avoid iatrogenic injury to the radial nerve during exploration.

The use of oxygen uptake rate to monitor discovery of microbial and enzymatic biocatalysts.

Arising from the requirement for discovery of novel biocatalysts with unusual properties, a process was developed which uniquely combines aspects of continuous culture with the measurement of oxygen uptake. This adaptation of the chemostat can be used to facilitate the isolation of a number of microorganisms with desirable properties, particularly those with useful metabolic capabilities and/or enzymes. The technique was also used to provide feedback on the metabolic status of a microbial population and increase the feed flow rate (i.e., dilution rate) thereby enabling the isolation of microorganisms with enhanced 1,3-propanediol dehydrogenase activity. The use of oxygen uptake as an indicator of cellular activity enables indirect measurement of substrate utilization and provides a real-time online assessment of the status of microbial enrichment or evolutionary processes and provides an opportunity, through the use of feedback systems, to control these processes. To demonstrate the utility of the technique, oxygen uptake rate (OUR) was compared with a range of conventional analytical techniques that are typically used to monitor enrichment/evolutionary processes and showed good correlation. Further validation was demonstrated by monitoring a characterizable microbial population shift using OUR. The population change was confirmed using off-line analytical techniques that are traditionally used to determine microbial activity. OUR was then used to monitor the enrichment of microorganisms capable of using a solvent (1-methyl-2-pyrrolidinone) as the sole source of carbon for energy and biomass formation from a heterogeneous microbial population. After purification the microorganisms taken from the enrichment process were able to completely utilize 1 g L(-1) 1-methyl-2-pyrrolidinone within 24 h demonstrating that the technique had correctly indicated the enriched population was capable of growth on 1-methyl-2-pyrrolidinone. The technique improves on conventional microbial enrichment that utilizes continuous culture by providing a real-time assessment of the enrichment process and the opportunity to use the OUR output for automated control and variation of one or more growth parameters.