Comprehensive Systematic Review Update Summary: Disorders of Consciousness: Report of the Guideline Development,Dissemination, and Implementation Subcommittee of the American Academy of Neurology; the American Congress of Rehabilitation Medicine; and the National Institute on Disability,Independent Living,and Rehabilitation Research

Objective

To update the 1995 American Academy of Neurology (AAN) practice parameter on persistent vegetative state and the 2002 case definition for the minimally conscious state (MCS) by reviewing the literature on the diagnosis, natural history, prognosis, and treatment of disorders of consciousness lasting at least 28 days.

Skeletal muscle ventricles as left atrial-aortic pumps: short-term studies.

In 5 dogs, skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle and placed in the left hemithorax. After a 3-week vascular delay period, SMVs were electrically preconditioned with 2-Hz stimulation for 6 weeks. At a second operation, SMVs were connected between the left atrium and thoracic aorta by afferent and efferent aortic root homografts, and stimulated to contract in a 1:2 diastolic mode. At a mean left atrial pressure of 12.4 +/- 1.3 mm Hg and a burst stimulation frequency of 33 Hz, SMV stroke volume was initially 43% of that of the native left ventricle, achieving a flow equivalent to 21% of cardiac output (194 +/- 38 versus 902 +/- 85 mL/min). At 50-Hz stimulation, this figure rose to 27% (246 +/- 41 mL/min; p less than 0.05). Skeletal muscle ventricle power output (the product of stroke work and contraction rate) at 33 Hz was 0.016 +/- 0.003 W, increasing to 0.024 +/- 0.004 W at 50 Hz (p less than 0.05), corresponding to 14% and 22%, respectively, of left ventricular power output (0.11 +/- 0.012 W). After 4 hours of continuous pumping, four of the SMVs were still generating flows of more than 70% of starting values and more than 60% of initial power output. This study demonstrates that SMVs can function in the systemic circulation at physiologic left atrial preloads.     

Nutritional support in surgical practice: Part I

Critical evaluation of the therapeutic benefit gained from provision of nutritional support requires knowledge regarding the nutritional status of those to whom it was given. The apparent effect of giving parenteral nutrition or enteral nutrition depends not only on how much and how well it is given, but also on how depleted the recipient is. Thus, nutritional assessment requires close examination before proceeding to assess the efficacy and potential benefits of the remedial measures of parenteral nutrition or enteral nutrition. Although preoperative malnutrition is associated with a poor operative outcome, there appears to be no consensus as to whether perioperative nutritional support can reduce postoperative complications to the level occurring in well-nourished patients undergoing similar procedures. This is partly because reports evaluating the effect of perioperative nutritional support on postoperative outcome vary widely as to numbers of patients studied, primary diagnoses, and the duration and quality of perioperative nutritional support. In Part I, these issues are explored in patients who are undergoing operations for cancer, trauma, or burns. Enteral nutrition appears to be as effective as parenteral nutrition in improving operative outcome, as compared with ad libitum oral nutrition. Postoperative enteral nutrition and parenteral nutrition are equally effective in reducing postoperative complications.     

The case of medium-dependent dual mechanisms for photoisomerization: one-bond-flip and hula-twist

This paper critically reviews examples in the literature of photochemical cis-trans isomerization paying particular attention to the medium effect and accompanied conformational changes. A case is made that the Hula-Twist mechanism, postulated in 1985 as a photochemical reaction pathway for a polyene chromophore imbedded in a protein binding cavity such as those of rhodopsin and bacteriorhodopsin, is also a dominant reaction pathway for a diene, or a longer polyene confined in a rigid (relative to isomerization rate) medium. The conventional one-bond-flip process is the preferred reaction pathway in a fluid medium. While defining experiments are proposed, this dual mechanistic approach successfully accounts for all examples in the literature on photoisomerization reactions whether involving conformational changes or not.