CTLA4 Autoimmunity-Associated Genotype Contributes to Severe Pulmonary Tuberculosis in an African Population

The gene of Cytotoxic T Lymphocyte-associated Antigen 4 (CTLA4), a negative regulator of T lymphocytes, contains a single-nucleotide polymorphism (SNP) at position +6230A->G (ct60A->G), which has been found associated with several autoimmune diseases and appears to reduce T-cell inhibitory activity. In Ghana, West Africa, we compared the frequencies of CTLA4 +6230 A/G and 6 haplotype-tagging SNPs in 2010 smear-positive, HIV-negative patients with pulmonary tuberculosis (TB) and 2346 controls matched for age, gender and ethnicity. We found no difference in allele frequencies between cases and controls. However, +6230A and a distinct CTLA4 haplotype and a diplotype comprising the +6230A allele were significantly less frequent among cases with large opacities in chest radiographs compared to those with small ones (P_{corrected [cor]} = 0.002, P_cor = 0.00045, P = 0.0005, respectively). This finding suggests that an increased T-cell activity associated with the CTLA4 +6230G allele contributes to pathology rather than to protection in pulmonary TB.     

Effect of darkening the cotyledons on the growth and curvature of the sunflower hypocotyl: evidence of hydraulic signalling

When both cotyledons of light-grown sunflower seedlings (Helianthusannuus L.) were darkened by covering them with aluminium foil,the resulting increase in the rate of elongation of the hypocotylwas closely proportional to the associated reduction in seedlingtranspiration and to the increase in xylem water potential (_PX.Covering only one cotyledon induced curvature away from thatside. This response was associated with a higher _PX in the vascularbundles connected directly with the covered cotyledon than inthose connected with the illuminated cotyledon. The water contentof peripheral tissues of the hypocotyl below the covered cotyledonwas also higher than that of similar samples from below theilluminated cotyledon. These results are consistent with thehypothesis that the effect of darkening the cotyledons on thegrowth and curvature of the hypocotyl is mediated by hydraulicsignalling, characterized by transmission to the hypocotyl ofan increase in _PX resulting from the reduction in cotyledontranspiration. Key words: Cotyledons, Helianthus annuus, hydraulic signalling, hypocotyl, transpiration, water potential     

Estimation of whole-plant resistance to gaseous exchange independent of leaf temperature measurement

For studies into the uptake of mercury vapor by wheat (Triticum aestivum), a simple theory and plant chamber were employed to estimate total leaf resistance of whole plants to water vapor exchange. The estimates were independent of leaf temperature, for which mean values were indirectly determined. The approach involved the measurement, at steady-state conditions, of the net change in water vapor flux per unit of leaf surface (Δq_v) in response to a small induced change in absolute humidity (ΔC_a). Assuming that total leaf resistance (r_l) was constant and that change in leaf temperature (T_l) was negligible, total leaf resistance was calculated from the equation, [Formula: see text]     

Burn syndactyly.

When the entire digital web space has been destroyed by burn scarring and there is a contracture of the volar aspect of the web as well as the dorsum, Z-plasties and skin grafts alone seldom produce a satisfactory web space. During the past 3 years, for the release of 46 contracted web spaces in 20 burned patients, we have turned a rectangular flap from the dorsal surface of the web through into an inverted-T incision in the palm. The adjacent sides of the defects have been skin grafted. In all these patients, we obtained satisfactory release of the contracture and restoration of the web space.     

The isolation of peptides by high-performance liquid chromatography using predicted elution positions

This paper describes the derivation and use of predictive retention coefficients for the reversed-phase high-performance liquid chromatography of peptides. The use of predicted elution positions in the isolation of peptides is illustrated by two examples where peptides, whose existence was postulated from cDNA sequence data, have been successfully isolated. The combination of the powerful chromatographic technology and the ability to predict the elution positions of peptides based on their composition provides a very potent method for the isolation of peptides from biological tissues.     

Inhibition of mitosis in fertilized sea urchin eggs by inhibition of the cyclic AMP-dependent protein kinase

Inhibition of cAMP-dependent protein kinase activity by microinjection of a specific physiologic protein inhibitor into sea urchin eggs inhibits the first cleavage after fertilization. Inhibition apparently occurs at some time prior to or during formation of the mitotic spindle. Measurement of the total protein kinase activity of sea urchin egg homogenates after fertilization showed that cAMP-dependent phosphorylation increases after fertilization and then declines prior to or at the time of the first cleavage. It is concluded that a cAMP-dependent phosphorylation plays a significant role in events leading to regulation of mitotic spindle assembly.     

A relationship between weight loss during food deprivation and subsequent meal size in the locust, Chortoicetes terminifera

Sizes of meals of 0·5 M sucrose taken by adults of either sex of Chortoicetes terminifera showed a strong positive correlation with the weight loss of the insects during the preceding 24 hr period of food deprivation. The relationship was less marked in males fed water, and there was no relationship in those fed 1·0 M sucrose. Meal size in females fed water was as strongly weight loss dependent as in those fed 0·5 M sucrose, but was less so in those fed 1·0 M sucrose. The results indicated that changes occurring after the completion of gut emptying influence meal size.