Cry1A toxins of Bacillus thuringiensis bind specifically to a region adjacent to the membrane-proximal extracellular domain of BT-R(1) in Manduca sexta: involvement of a cadherin in the entomopathogenicity of Bacillus thuringiensis.

Many subspecies of the soil bacterium Bacillus thuringiensis produce various parasporal crystal proteins, also known as Cry toxins, that exhibit insecticidal activity upon binding to specific receptors in the midgut of susceptible insects. One such receptor, BT-R(1) (210 kDa), is a cadherin located in the midgut epithelium of the tobacco hornworm, Manduca sexta. It has a high binding affinity (K(d) approximately 1nM) for the Cry1A toxins of B. thuringiensis. Truncation analysis of BT-R(1) revealed that the only fragment capable of binding the Cry1A toxins of B. thuringiensis was a contiguous 169-amino acid sequence adjacent to the membrane-proximal extracellular domain. The purified toxin-binding fragment acted as an antagonist to Cry1Ab toxin by blocking the binding of toxin to the tobacco hornworm midgut and inhibiting insecticidal action. Exogenous Cry1Ab toxin bound to intact COS-7 cells expressing BT-R(1) cDNA, subsequently killing the cells. Recruitment of BT-R(1) by B. thuringiensis indicates that the bacterium interacts with a specific cell adhesion molecule during its pathogenesis. Apparently, Cry toxins, like other bacterial toxins, attack epithelial barriers by targeting cell adhesion molecules within susceptible insect hosts.

The relationship between axillary and core body temperature measurements.

The goal of this study was to assess the accuracy of the axillary site as an indicator of core body temperature. Data from 30 core body temperatures, 30 electronic axillary temperatures, and 30 mercury-in-glass axillary temperatures in nonpostoperative intensive care unit patients are reported. Core and axillary temperatures were simultaneously measured in each patient. The correlation between core and axillary-mercury was r = 0.90. The mean difference between core and axillary-mercury was 0.35 degrees F (0.19 degrees C). The correlation between core and axillary-electronic was r = .87. The mean difference between core and axillary-electronic was 0.6 degrees F (0.33 degrees C). Only three, or 5%, of the 60 core-axillary pairs met the expected 2 degrees F (1.2 degrees C) difference. These findings support the accuracy of axillary temperature measurement as a reflection of core body temperature measurement in nonpostoperative patients. These researchers suggest that mercury thermometers be used in cases where small differences in temperature are clinically meaningful.