Atmospheric Pollution with Halothane during Outpatient Dental Anaesthesia

Pollution of the atmosphere with halothane has been measured during general anaesthesia for outpatients undergoing dental extractions. The level of contamination was far in excess of that recorded in surgical operating theatres, and halothane was inhaled at similar concentrations by both the anaesthetist and the dental surgeon. The room air-changing system and a local fan had little effect on contamination. Scavenging devices on the exhalation valve of the anaesthetic circuit were only moderately effective in reducing the concentration of halothane in the atmosphere.     

Class II MHC quantitative binding motifs derived from a large molecular database with a versatile iterative stepwise discriminant analysis meta-algorithm.

MOTIVATION: The identification of T-cell epitopes can be crucial for vaccine development. An epitope is a peptide segment that binds to both a T-cell receptor and a major histocompatibility complex (MHC) molecule. Predicting which peptide segments bind MHC molecules is the first step in epitope prediction. RESULTS: An iterative stepwise discriminant analysis meta-algorithm explores a large molecular database to derive quantitative motifs for peptide binding. The applications presented here demonstrate the algorithm's versatility by producing four closely related models for HLA-DR1. Two models use an expert initial estimate and two do not; two models use amino acid residues as the only predictors and two use amino acid groupings as additional predictors. Each model correctly classifies >90% of the peptides in the database. AVAILABILITY: Software is available commercially; data are free over the Internet.     

Multiple mutations of MYO1A,a cochlear-expressed gene,in sensorineural hearing loss

Myosin I isozymes have been implicated in various motile processes, including organelle translocation, ion-channel gating, and cytoskeleton reorganization. Unconventional myosins were among the first family of proteins found to be associated with hearing loss in both humans and mice. Here, we report the identification of a nonsense mutation, of a trinucleotide insertion leading to an addition of an amino acid, and of six missense mutations in MYO1A cDNA sequence in a group of hearing-impaired patients from Italy. MYO1A, which is located within the DFNA48 locus, is the first myosin I family member found to be involved in causing deafness and may be a major contributor to autosomal dominant-hearing loss.     

Temporal Intra-Individual Variation of Immunological Biomarkers in Type 1 Diabetes Patients: Implications for Future Use in Cross-Sectional Assessment

Multiple immune parameters such as frequencies of autoreactive CD4⁺, CD8⁺ T-cells and CD4⁺CD25⁺Foxp3⁺ T-cells have been explored as biomarkers in human T1D. However, intra-individual temporal variation of these parameters has not been assessed systematically over time. We determined the variation in each of these parameters in a cohort of T1D and healthy donors (HDs), at monthly intervals for one year. Despite low intra- and inter-assay co-efficient of variation (CV), mean CVs for each of the immune parameters were 119.1% for CD4⁺ T-cell-derived IFN-γ, 50.44% for autoreactive CD8⁺ T-cells, and 31.24% for CD4⁺CD25⁺Foxp3⁺ T-cells. Further, both HDs and T1D donors had similar CVs. The variation neither correlated with BMI, age, disease duration or insulin usage, nor were there detectable cyclical patterns of variation. However, averaging results from multiple visits for an individual provided a better estimate of the CV between visits. Based on our data we predict that by averaging values from three visits a treatment effect on these parameters with a 50% effect size could be detected with the same power using 1.8–4-fold fewer patients within a trial compared to using values from a single visit. Thus, our present data contribute to a more robust, accurate endpoint design for future clinical trials in T1D and aid in the identification of truly efficacious therapies.     

A noncoding point mutation of Zeb1 causes multiple developmental malformations and obesity in Twirler mice

Heterozygous Twirler (Tw) mice develop obesity and circling behavior associated with malformations of the inner ear, whereas homozygous Tw mice have cleft palate and die shortly after birth. Zeb1 is a zinc finger protein that contributes to mesenchymal cell fate by repression of genes whose expression defines epithelial cell identity. This developmental pathway is disrupted in inner ears of Tw/Tw mice. The purpose of our study was to comprehensively characterize the Twirler phenotype and to identify the causative mutation. The Tw/+ inner ear phenotype includes irregularities of the semicircular canals, abnormal utricular otoconia, a shortened cochlear duct, and hearing loss, whereas Tw/Tw ears are severely malformed with barely recognizable anatomy. Tw/+ mice have obesity associated with insulin-resistance and have lymphoid organ hypoplasia. We identified a noncoding nucleotide substitution, c.58+181G>A, in the first intron of the Tw allele of Zeb1 (Zeb1(Tw)). A knockin mouse model of c.58+181G>A recapitulated the Tw phenotype, whereas a wild-type knockin control did not, confirming the mutation as pathogenic. c.58+181G>A does not affect splicing but disrupts a predicted site for Myb protein binding, which we confirmed in vitro. In comparison, homozygosity for a targeted deletion of exon 1 of mouse Zeb1, Zeb1(ΔEx1), is associated with a subtle abnormality of the lateral semicircular canal that is different than those in Tw mice. Expression analyses of E13.5 Twirler and Zeb1(ΔEx1) ears confirm that Zeb1(ΔEx1) is a null allele, whereas Zeb1(Tw) RNA is expressed at increased levels in comparison to wild-type Zeb1. We conclude that a noncoding point mutation of Zeb1 acts via a gain-of-function to disrupt regulation of Zeb1(Tw) expression, epithelial-mesenchymal cell fate or interactions, and structural development of the inner ear in Twirler mice. This is a novel mechanism underlying disorders of hearing or balance.