SummarySixty ASA grade 1 or 2 patients, aged 60 years or over, scheduledfor surgery to the lower abdomen or lower limbs under spinal anaesthesia w e e allocated randomly to one of three treatment groups. Group A received 16 mllkg of Ringer's acetate solution immediately before spinal anaesthesia, group B received 8 mljkg and group C received no volume preload. Heart rate, arterial pressure and anaesthetic level were recorded by an independent observer. The overall incidence of systemic arterial hypotension (defined as a decrease of 25% or more in systolic arterial pressure) was 27%; there were no significant difSerences among groups. The overall incidence of hypotension was 60%, when temperature sensation was blocked to T, and above ( n = 25). The number of patients with hypotension which required treatment increased as block height increased above T,; at a level of T, or higher, all patients required ephedrine. Crystalloid preloading had no effect on the incidence of hypotension after spinal anaesthesia in ,fit, elderly patients. Key wordsAnaesthetic technique; spinal. Complications; hypotension.Arterial hypotension during spinal anaesthesia may be associated with significant patient discomfort and even mortality.' Crystalloid preloading is recommended in some textbooks2 as a means whereby the incidence or degree of hypotension is reduced, and is common research practice.5-' However, it is not a universal r e c o m m e n d a t i~n~~~ since its value has only been tested in a n obstetric population.1° The purpose of this study was to assess the value of volume preload with crystalloid solution in a group of elderly patients. MethodEthics committee approval was obtained for this study, and informed consent obtained from each patient. Sixty ASA grade 1 or 2 patients scheduled for elective lower abdominal or lower limb surgery under spinal anaesthesia were entered into the study.All patients were prernedicated with oral diazepam 2 hours before anaesthesia, 5-15 mg, depending on body weight. An electrocardiograph was connected before spinal anaesthesia, and three measurements of systolic and diastolic arterial pressures were made using an oscillotonometer. A large-bore intravenous cannula was inserted. The patient was then assigned randomly to receive 16, 8 or 0 ml/kg Ringer's acetate solution immediately before spinal anaesthesia. The preload was given over 5-10 minutes, using a pressure infusion device if necessary.One of the authors (A.J.C.), who had no knowledge of the preload used, then performed spinal anaesthesia. Three to four ml plain bupivacaine 0.5% was given through a 26-gauge needle a t the L,-L, interspace. Heart rate, systolic and diastolic arterial pressures were measured at 3-minute intervals, and the height of block assessed using an ethyl chloride spray. Increments of intravenous ephedrine 5 mg were administered to restore arterial pressure if systolic arterial pressure decreased by more than 25% of the lowest of the three baseline measurements. Atropine 0.3-0.6 mg was given if heart rate decrease...

The genomic duplication associated with Potocki-Lupski syndrome (PTLS) maps in close proximity to the duplication associated with Charcot-Marie-Tooth disease type 1A (CMT1A). PTLS is characterized by hypotonia, failure to thrive, reduced body weight, intellectual disability, and autistic features. CMT1A is a common autosomal dominant distal symmetric peripheral polyneuropathy. The key dosage-sensitive genes RAI1 and PMP22 are respectively associated with PTLS and CMT1A. Recurrent duplications accounting for the majority of subjects with these conditions are mediated by nonallelic homologous recombination between distinct low-copy repeat (LCR) substrates. The LCRs flanking a contiguous genomic interval encompassing both RAI1 and PMP22 do not share extensive homology; thus, duplications encompassing both loci are rare and potentially generated by a different mutational mechanism. We characterized genomic rearrangements that simultaneously duplicate PMP22 and RAI1, including nine potential complex genomic rearrangements, in 23 subjects by high-resolution array comparative genomic hybridization and breakpoint junction sequencing. Insertions and microhomologies were found at the breakpoint junctions, suggesting potential replicative mechanisms for rearrangement formation. At the breakpoint junctions of these nonrecurrent rearrangements, enrichment of repetitive DNA sequences was observed, indicating that they might predispose to genomic instability and rearrangement. Clinical evaluation revealed blended PTLS and CMT1A phenotypes with a potential earlier onset of neuropathy. Moreover, additional clinical findings might be observed due to the extra duplicated material included in the rearrangements. Our genomic analysis suggests replicative mechanisms as a predominant mechanism underlying PMP22-RAI1 contiguous gene duplications and provides further evidence supporting the role of complex genomic architecture in genomic instability.

CD73 is a glycosyl phosphatidylinositol-anchored protein with both ecto-enzyme activity (ecto-5'-nucleotidase) and signal transducing capabilities for human T lymphocytes. We now report an analysis of the distribution and function of CD73 in murine lymphoid tissues made possible by the development of the first monoclonal antibodies (mAb) specific for murine CD73. Subsets of T and B lymphocytes are CD73+ and the level of expression increases with lymphocyte maturation in both species. Among B cells, CD73 is largely restricted to cells which have undergone isotype switching. The signal transmitting function of CD73 is also conserved, as splenic T cells treated with anti-CD73 mAb plus phorbol 12-myristate 13-acetate proliferate and secrete IL-2. Fyn-/- mice are unresponsive to CD73 ligation, however, demonstrating the requirement for this tyrosine kinase in CD73-mediated signal transduction. CD73 is down-regulated after mAb plus cross-linking, suggesting that expression may be controlled by interaction with a ligand. Only small numbers of thymocytes are CD73+, so CD73 receptor functions are unlikely to be important for developing T cells. However, immunohistochemical analysis reveals that reticular and vascular cells throughout the thymus and other lymphoid tissues are markedly CD73+. Therefore, CD73 might mediate lymphocyte-stromal cell interactions or condition the local microenvironment to facilitate lymphocyte development and/or function.

The Bair Hugger system is a new and highly effective active patient warming system which produces a layer of warm air between the patient and the warming system. We report an instance of marked softening and distortion of a polyvinyl chloride tracheal tube caused by this layer. We also present laboratory data indicating that this is a likely problem under routine theatre conditions, with suggestions for prevention.