Violent emergence from anesthesia: is it a pharmacological or psychological reaction?

A violent emergence from deep sedation is an uncommon reaction in the daily practice of anesthesia in the oral and maxillofacial surgery office. We present a case of a 22-yr-old male with a severe violent emergence from deep sedation that we attribute to a psychological rather than a pharmacological cause. A differential diagnosis is discussed, as are methods of treatment.     

Positive effects of allosteric modulators on the binding properties and the function of muscarinic acetylcholine receptors

Data are reviewed indicating that allosteric modulators can enhance the affinities of muscarinic receptors for their antagonists and agonists, that the enhancement of the affinity for agonists is relevant functionally, and that the allosterically induced conformational change also affects the interaction between the receptors and the G proteins.     

Brain iron, transferrin and ferritin concentrations are altered in developing iron-deficient rats

To study the iron, transferrin, and ferritin distribution at subcellular levels in response to acute dietary iron deficiency, we tested the hypothesis that early post-weaning iron deficiency can change iron and iron regulatory protein concentrations in rat brain. Male Sprague-Dawley rats were fed diets containing either 2 or 35 micrograms iron/g for 2, 3 or 4 wk starting at 21 d of age. Brain iron, transferrin and ferritin concentrations in cytosolic and microsomal fractions of either whole brain or pons and cerebellum were then determined. After 14 d of dietary iron restriction, brain iron concentrations were 50% lower in the microsomal fraction and 30% lower in cytosol compared with controls. Brain cytosolic transferrin concentration almost doubled in the same animals. Brain ferritin concentration in fractions from rats fed the iron-deficient diet for 14 d was lower than in controls, but then remained fairly constant. Absolute brain weight and total brain protein contents were unaffected by iron restriction. This study extends previous research by demonstrating that the brain responds to changes in body iron status with a change in transferrin concentration. If the dietary restriction is quite severe, this adaptation is insufficient. This study also notes that brain ferritin decreases with decreasing body iron status, though it was less responsive than nonheme iron in liver. The concept that iron enters the brain through a highly regulated endocytotic process at the blood brain barrier, that undoubtedly involves the regulation of transferrin receptors in capillary endothelial cell, is supported by our observation of elevated transferrin concentrations in brain of iron-deficient rats.     

MR of the heart under pharmacologic stress

Magnetic resonance imaging is one method for assessing cardiac function and perfusion at rest and under stress conditions. In this article, the potential of stress magnetic resonance imaging for evaluating ischemic heart disease is reviewed, and technical aspects of some developments that may contribute to comprehensive magnetic resonance imaging assessment of heart disease under rest and stress are discussed.     

Increased flight surgeon role in military aeromedical evacuation

BACKGROUND: Physicians were involved in the development of aeromedical evacuation (medevac) and flight surgeons flew as crewmembers on the first U.S. military medevac flights. However, since World War II flight surgeons have not been routinely assigned to operational medevac units. The aeromedical literature addressing the role of physicians in medevac is controversial. Recent contingencies involving the U.S. Air Force (USAF) have required the augmentation of medevac units with flight surgeons. RECENT CHANGES IN THE EUROPEAN THEATER: Beginning in 1992, the United States Air Forces Europe (USAFE) assigned three flight surgeons to the medevac squadron. Between 2 February 1993 and 24 March 1994 USAFE moved 241 patients on 29 missions out of the former Yugoslavia--most of these missions had a flight surgeon on the crew. Because advance medical information on the status of these patients is often nonexistent, the presence of a physician on the crew proved life-saving in some instances. In peacetime operations, there has been a recent trend in the European theater for the USAF to move more unstable patients. OBSERVED BENEFITS OF PHYSICIANS IN MEDEVAC: Dedicated medevac flight surgeons have proven to have the specific experience and training to perform effectively in the role of in-flight medical attendant. In addition, they are effective in negotiating with referring physicians about the urgency of movement, required equipment, the need for medical attendants, etc. These flight surgeons also provide medical coverage of transiting patients in the Aeromedical Staging Flight (ASF), thus providing needed continuity in the medevac system. CONCLUSION: Dedicated medevac flight surgeons fill a unique and valuable role in medevac systems. Agencies with medevac units should consider assigning flight surgeons to these units.     

Physiological analysis of stress-induced changes in the suppressor activity of mouse T-lymphocytes

BACKGROUND: Despite their potential therapeutic benefit, the effects of cholinergic agents on anal function have been poorly investigated. AIM: To analyse the effects of neostigmine and atropine on anorectal responses to rectal isobaric distension. METHODS: This was a placebo-controlled, randomized, double-blind crossover study, performed in 12 healthy volunteers who received intravenously, on 3 separate days, neostigmine, atropine or the placebo. During each day of the experiment, seven pressure steps (ranging from 1 to 31 mmHg) in three different protocols of rectal isobaric distension (phasic, stepwise and tonic) were applied using an electronic barostat. Manometric responses of the anal canal, adaptative volumes and perception scores of the rectum were recorded. RESULTS: During stepwise distension, a significant drug effect was encountered at the anal level. No drug effect was observed on the other investigated parameters (rectal volumes and rectal perception scores) or for the other modes of distension. Compared to placebo, neostigmine significantly decreased pressures at the upper level of the anal canal for both recto anal inhibitory reflex and mean resting pressures. In contrast, atropine significantly increased pressures at the lower part of the anal canal but did not modify upper anal pressures. CONCLUSION: The present study suggests that cholinergic effects result more from an indirect action on intermediate neurotransmitters and rectal myenteric neurons, than from a direct action on anal targets.