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Although many human major histocompatibility genes have been identified, relatively few have been localized to the class I region. We searched for new class I region genes by sample sequencing, a process in which short stretches of random genomic sequence are generated from cosmids and then compared with sequences deposited in nucleotide databases. Four class I region cosmids were isolated for sample sequencing by screening a chromosome 6 specific cosmid library with probes derived from specific class I region genes or with overlapping class I region yeast artificial chromosomes. Cosmids were sonnicated to produce fragments of 0.5 - 1 kilobases, subcloned, and sequenced using an automated sequencer. Sequences were then compared with nucleotide sequences deposited in the GenBank databases using the BLASTN algorithm. A number of potential new class I region genes were identified, including a cDNA with similarity to the tre oncogene, the trans-activating factor SC1 (TCF19), and a member of the interferon inducible 1 - 8 gene family. These observations suggest that sample sequencing is an efficient method for identifying new class I region genes, which can be applied to other regions of the genome and to other species, and support previous observations that the class I region contains a variety of genes other than those encoding HLA antigens.

A gas chromatographic (GC) assay for the determination of SCH 44643, an orally active antagonist of responses to both histamine and PAF, was developed and validated for rat plasma. The method involved organic solvent extraction followed by solid phase extraction on aminopropyl column. The separation was on a capillary column (DB-17) with quantitation by a nitrogen-phosphorus detection. The method was sensitive with a limit of quantitation of 5 ng mL−1. There was a good linear relationship between the peak height ratio (SCH 44643/internal standard) and SCH 44643 concentration in the range 5 to 200 ng mL−1. The method was precise with a coefficient of variation ranging from 1.8 to 3.0% and accurate with a bias ranging from 0 to 5.8%. Moreover, SCH 44643 was stable in rat plasma after being subjected to three freeze-thaw cycles. The assay was shown to be sensitive, specific, accurate and precise, and suitable for use in pharmacokinetic or toxicokinetic studies.

The sequence of troponin I from fast and slow skeletal and cardiac muscle shows strong homology in the region which binds to actin and is responsible for inhibition of the actomyosin AT Pase. More differences are found in the N-terminal region which binds to troponin C.

STUDIES of the three chief classes of immunoglobulins in the rabbit, IgG, IgA and IgM, have shown that they all possess the basic four chain structure proposed by Porter1 of two light and two heavy chains, and that while the light chains are common to all three classes the heavy chains, γ, α and μ respectively, are class specific, and differ considerably as judged by pep tide mapping2,3. Despite these differences in the heavy chains the allotypic specificities at the a locus, Aa1, Aa2 and Aa3 (ref. 4), are present not only on the γ chain but also on the α and μ-chains5–7. These specificities have been shown to be on the Fd fragment of γ-chain8 and appear to correlate with the N-terminal sequence of that chain9. In the light of these findings it seemed reasonable to expect that similar structures would be present in the N-terminal sequence of both a and μ-chains, and I have attempted to show this by determining the N-terminal sequence of α-chain from rabbits homozygous for the allotypes Aa1 and Aa3.