Elephantfish proinsulin possesses a monobasic processing site.

Total pancreatic RNA from the holocephalan species Callorhyncus milii (elephantfish) was used to make cDNA as a template for the polymerase chain reaction. Three redundant primers based on the known amino acid sequence of elephantfish insulin were used to amplify a fragment of proinsulin comprising truncated B-chain, complete C-peptide, and complete A-chain. Whereas the C-peptide/A-chain junction contained the expected dibasic cleavage site (-Lys-Arg-), the B-chain/C-peptide junction was found to contain only a single Arg, the first such site to be unequivocally associated with the proteolytic processing of a proinsulin to insulin. Examination of the flanking sequences around this site shows that a typical endocrine/neuroendocrine PC3 conversion enzyme should still be able to cleave, as the general requirements for precursor processing at a monobasic site are satisfied, notably a basic residue (Lys) at the -4 position. An acidic residue (in this case Asp) at the +1 position, which is seen in all known proinsulins, is maintained. The corresponding genomic DNA fragment of elephantfish proinsulin was also amplified by PCR, revealing a 402-bp intron at the conserved IVS-2 position within the C7 codon.

Subjective perceptual methods for comparing backpacks.

Subjective perceptual methods may provide useful information about small differences in backpack design when physiological and biomechanical comparisons are ineffective. This study used two subjective perceptual methods, category ratio scale (CRS) ratings of perceived discomfort and written questionnaires for comparing two types of leisure backpack. CRS ratings of perceived discomfort for each of 24 body regions after 30 min of uphill (15% grade) treadmill walking at 3 km h-1 in 10 males, failed to distinguish between a New Zealand designed backpack (Pack A) and a British designed backpack (Pack B), each weighted to 20 kg. A simple pre- and post-walking written questionnaire using either a visual analogue linear scale or free-format responses indicated that more subjects found Pack A easier to adjust but that it had less comfortable shoulder and waist straps. It was considered to be more comfortable with regard to balance and posture and for shoulder, back and leg muscular tension. Pack B was initially more comfortable but required more lumbar support. Pack B was considered more comfortable for waist and shoulder pressure only. Overall preference was for Pack A (seven subjects) rather than Pack B (three subjects). In conclusion, in this study a questionnaire approach was found to be more useful than CRS ratings of perceived discomfort and the New Zealand designed backpack was preferred.

Population study of T cell receptor V beta gene usage in peripheral blood lymphocytes: differences in ethnic groups.

The T cell receptor (TCR) V beta repertoire in peripheral blood lymphocytes (PBL) of a large number of healthy individuals was analysed by quantifying V beta-specific mRNA using the method of anchored multiprimer DNA amplification and a reverse dot blot assay. Among 16 V beta gene families examined, particular V beta genes were noted to be unequally expressed in the PBL of 70 healthy donors. The frequently used genes belong to the V beta 4, 5, 6, 8 and 13 (12) families, while V beta 1, 9 and 15 were the least frequently used gene families. This bias in gene usage was observed in all individuals. Marked deviation from the mean percentage usage was noted for some V beta genes in individuals when their PBL were examined serially, but the common pattern of biased usage was not grossly distorted. When the TCR repertoire of different ethnic groups was examined, a lower mean frequency of V beta 3.2 was seen in the repertoire of 19 Caucasians compared with 25 age-matched Samoans (P < 0.003). Conversely, the expression of V beta 5.1 and V beta 5.3 was higher in Caucasians than in 51 age-matched Polynesians (Maoris and Samoans, P < 0.003). Considering the 20% co-efficient of variation in the estimate of V beta gene usage, our data from 70 unrelated individuals suggest that in PBL, individual variations in the TCR repertoire were superimposed upon a common biased usage of V beta genes in the general population.