Artificial receptors involved in enolization and pK(a) shifts.

Abiotic receptors used to enolize carbonyl compounds or to shift substrate pK(a) values are reviewed. These systems exhibit disparate frameworks and several approaches to binding and anion stabilization. Detailed emphasis is placed on a bicyclic cyclophane that induces pK(a) shifts in active methylene compounds through NH-pi hydrogen bonding with the resultant enolates.

The effects of positional restraint on heart rate and oxygen saturation.

To study the effects of positional restraint on heart rate and oxygen saturation during recovery, a crossover experimental design with prospective control trials was used in a two-phase study. In phase 1, serial resting oxygen saturations (RO1) measured on 18 volunteers were compared with those measured in the seated unrestrained (SU1) and the hogtie (HT) positions after submaximal cycle exercise. Additionally, serial heart rates were compared postexercise on subjects in the SU1 and HT positions. In phase 2, resting oxygen saturations (RO2) were compared with those measured in the seated unrestrained (SU2) position and an alternate maximal restraint (MR) position after a simulated pursuit and struggle scenario. No statistical differences were found between SU1 and HT recovery heart rates in phase 1. Small oxygen saturation differences (1%) were found in both phase 1 and phase 2 between resting (RO1 and RO2) positions and those measured in the seated unrestrained (SUI), hogtie (HT), and maximal restraint (MR) positions. Oxygen saturations taken during a 5-min period in each of the three situations in phase 1 (RO1, SU1, and HT) were averaged, yielding 97.8, 98.0, and 97.6%, respectively. In phase 2, mean oxygen saturations were 98.0, 97.4, and 96.8% for RO2, SU2, and MR, respectively. In our study population, the use of hogtie and an alternate maximal restraint method did not result in any clinical restrictions in heart rate or oxygen saturation recoveries.

hMSH5: a human MutS homologue that forms a novel heterodimer with hMSH4 and is expressed during spermatogenesis.

MutS homologues have been identified in nearly all organisms examined to date. They play essential roles in maintaining mitotic genetic fidelity and meiotic segregation fidelity. MutS homologues appear to function as a molecular switch that signals genomic manipulation events. Here we describe the identification of the human homologue of the Saccharomyces cerevisiae MSH5, which is known to participate in meiotic segregation fidelity and crossing-over. The human MSH5 (hMSH5) was localized to chromosome 6p22-21 and appears to play a role in meiosis because expression is induced during spermatogenesis between the late primary spermatocytes and the elongated spermatid phase. hMSH5 interacts specifically with hMSH4, confirming the generality of functional heterodimeric interactions in the eukaryotic MutS homologue, which also includes hMSH2-hMSH3 and hMSH2-hMSH6.

Anion recognition: synthetic receptors for anions and their application in sensors.

Important contributions to the field of anion sensing include electrochemical lipophilic uranyl salophene receptors incorporated into membranes that act as fluoride-selective potentiometric microsensors. A promising optical-based sensor, selective for cyclic AMP, involves a preorganized, molecularly imprinted polymer employing an intrinsic fluorophore. Competition methods using ensembles of recognition units and external indicators have been used to sense citrate in highly competitive media and micromolar concentrations of inositol(tris)phosphate in water. In addition, DNA dendrimers immobilized on a quartz-crystal microbalance acted as an elegant biosensor for Cryptosporidium DNA. These designs display the varied methods of anion detection currently being pursued.

Fire in the operating room during tracheostomy.

BACKGROUND: Fire in the modern operating room is still a constant danger today despite the usual absence of the historically explosive anesthetic gases, cyclopropane, and ether. During a tracheostomy, three conditions are present that will support an explosive or combustive event: heat, fuel and oxygen. METHODS: We report three routine tracheostomy cases during which a fire was ignited. One patient had a minor burn during the cauterizing of a bleeding vessel. There was a visible flame in all cases and, in one case, the cloth drapes ignited. There were no serious airway injuries to any patients and all had a complete and uneventful recovery. We duplicated the same conditions in our laboratory. RESULTS: We discuss each case and give effective techniques to prevent ignition during surgery in the future. For our study, we reproduced flames in a cadaver trachea using halothane and the electrocautery in an oxygen-rich environment. We describe a protocol that has effectively prevented tracheostomy fires in our institution and may decrease the risk during other procedures as well. Also, we reviewed the literature to provide insight into the magnitude of the problem. CONCLUSIONS: High-oxygen concentration, the presence of fuels such as suture and tissue, and an igniting spark from the electrocautery device produce the proper conditions for a fire during tracheostomy. Taking the proper precautions can minimize if not eliminate this risk.

Alternating unilateral botulinum toxin type A (BOTOX) injections for spasmodic dysphonia.

Injection of botulinum toxin type A (BOTOX) into both thyroarytenoid muscles is an accepted treatment for spasmodic dysphonia. The authors of this study identified patients who could not tolerate the interval of breathy voice that immediately follows bilateral injections. These patients were offered a protocol in which the injection side was alternated on subsequent treatments. Eighteen patients who received at least two bilateral injections and two unilateral injections were reviewed. Alternating unilateral injections yielded a shorter breathy interval by an average of 12.7 days (P=.0007) and a shorter duration of return of spasmodic symptoms by an average of 26.0 days (P=.0006). Compared with bilateral injections, alternating unilateral injections yielded an average (median) of 3.2 more days of strong voice per day of breathy voice (P=.001). However, unilateral injections had a shorter average interval of strong voice (27.4 days; P=.007), as well as a slightly higher failure rate (4.9% vs. 1.1%). The authors conclude that alternating unilateral botulinum toxin type A injections are useful in patients with spasmodic dysphonia who have difficulty with the breathy voice that follows bilateral injection.

Case report: poorly differentiated carcinoma of unknown primary presenting as Trousseau's syndrome.

Two patients without clinical evidence of malignancy had idiopathic migratory thrombophlebitis. A clinical state consistent with Trousseau's syndrome prompted a work-up of each patient for occult cancer. In both individuals, computed tomography of the chest revealed a solitary mediastinal lymph node that, though inconspicuous, was evaluated further because of the clinical picture. Mediastinoscopy with biopsy revealed poorly differentiated carcinoma. Treatment was begun for carcinoma of unknown primary with variable response to therapy. The clinical presentation and pathophysiology of Trousseau's syndrome, as well as its use in leading to an antemortem diagnosis of occult cancer in these and other patients, are delineated.