Orthopaedic anesthesia - part 1. Commonly used anesthetic agents in orthopaedics.

Anesthesia is a broad discipline; for orthopaedic applications, the type and location of the planned orthopaedic procedure is important in the selection of the most appropriate anesthetic agent and technique. The purpose of this overview is to: 1. highlight the role of several anesthetic agents commonly used in an orthopaedic setting and 2. to familiarize the orthopaedist with those techniques of regional anesthesia that have implications for emergency rooms and other ambulatory settings. Because the subject matter is expansive in scope, it is necessary to address each of the above objectives separately, in two different articles. Part 1 describes anesthetic agents, whereas Part 2 encompasses techniques of administering regional anesthesia.

Orthopaedic anesthesia - part 2. Common techniques of regional anesthesia in orthopaedics.

Anesthesia may be considered in terms of two categories: general and regional. The aim of general anesthesia is to induce analgesia, sedation, amnesia, suppression of autonomic reflexes, and relaxation of muscles. Regional anesthesia is more site-specific and is typically divided into three categories based on the location of injection: 1. a central neuraxial block is an injection of an anesthetic drug into the epidural or intrathecal space; 2. a peripheral nerve block is an injection near the nerve or plexus supplying the area under operation; and 3. a field block is an injection into the adjoining tissues with subsequent diffusion into the surgical area (in orthopaedics, it is typically employed for minor procedures of the hand or foot). Of these three categories of regional anesthesia (i.e., neuraxial, peripheral, and field blocks), this article focuses on the latter two. Although neuraxial blocks comprise an important part of regional anesthesia, they are typically performed by anesthesiologists in an operative setting for major procedures of the lower extremities. The intent of this article is to familiarize the orthopaedist with techniques that have implications for emergency rooms and other ambulatory settings in which regional techniques are sometimes favored over general alternatives because they entail less risk of systemic side effects and may involve more cost-effective use of resources.

Genetic association of Alzheimer's disease with multiple polymorphisms in alpha-2-macroglobulin.

Alpha-2-Macroglobulin (A2M) is a highly plausible candidate gene for Alzheimer's disease (AD) in a region of chromosome 12 that has numerous independent reports of genetic linkage. We previously reported that a 5 bp deletion in A2M was associated with AD in a subset of the National Institute of Health (NIMH) Genetics Initiative AD family sample. Efforts to replicate this association finding in case - control samples have been largely negative, while those in family samples have been more positive. We hypothesized that variable findings regarding this deletion, along with variable reports of association with V1000I, another polymorphism in the gene, result from linkage disequilibrium in the area as well as ascertainment differences between family-based and case-control studies. Thus, we resequenced the A2M locus to identify novel polymorphisms to test for genetic association with AD. We identified seven novel polymorphisms and tested them in the full NIMH sample of 1439 individuals in 437 families. We found significant genetic association of the 5 bp deletion and two novel polymorphisms with AD. Substantial linkage disequilibrium was detected across the gene as a whole, and haplotype analysis also showed significant association between AD and groups of A2M polymorphisms. Several of these polymorphisms and haplotypes remain significantly associated with AD even after correction for multiple testing. Taken together, these findings, and the positive reports in other family-based studies, continue to support a potential role for A2M or a nearby gene in AD. However, the negative case - control studies suggest that any underlying pathogenic polymorphisms have a modest effect, and may operate primarily among individuals with a family history of AD.