Activation of cysteine proteases in cowpea plants during the hypersensitive response--a form of programmed cell death

The matrix metalloproteinases appear to play a key role in mammary tissue remodeling during involution. By immunoprecipitation and immunoblot using antibodies against 60K gelatinase which appears during involution a 90K polypeptide has been identified as its inactive proenzyme in the early involuting rat mammary gland. 90K polypeptide was isolated from the second day involuting rat mammary gland by immunoaffinity chromatography. On proteolytic digestion, the inactive 90K polypeptide was converted to active gelatinase. Primary cultures of mammary epithelial cells secreted the 90K polypeptide. These results indicated that the 60K inducible MMP involved in mammary gland involution and remodeling is produced as a 90K proenzyme which is activated by proteolysis in the extracellular sites.     

Interaction between proteins containing homeodomains associated to leucine zippers from sunflower

A strategy based on the use of PCR with one degenerate oligonucleotide deduced from conserved sequences and lambda gt10 primers was used to isolate homeobox containing sequences from sunflower stem and root cDNA libraries. Six different partial cDNAs coding for the first 48 amino acids of homeodomains and amino terminal sequences were analyzed and found to be members of the HD-Zip superfamily, which contain a homeobox linked to a leucine zipper coding region. A full-length cDNA clone, Hahb-10, was isolated and characterized. The leucine zipper portions of Hahb-10 and of the previously reported Hahb-1 have been utilized to construct fusions with the N-terminal domain of the lambda repressor. These fusions were tested for their ability to bind to lambda promoters in vivo. The expression of a protein containing an active dimerization domain, but not capable of DNA binding, exerts a dominant negative effect on the ability of repressor-zipper fusions to bind to its target DNA. From these experiments, it was concluded that Hahb-1 and -10, when co-expressed, form preferentially homodimers. Exchange of conserved threonines and leucines at positions a1 and d1 of both zippers reduces dimerization efficiency and allows the formation of heterodimers, suggesting that these residues are, among others, determinants of the specificity of interaction, most likely through changes in hydrophobic packing interactions at the dimer interface. The results imply that a great number of interacting molecular entities compose this protein superfamily which is presumably involved in regulating plant developmental responses.     

Agricultural use of antibiotics and the evolution and transfer of antibiotic-resistant bacteria

Microbial Resistance to antibiotics is on the rise, in part because of inappropriate use of antibiotics in human medicine but also because of practices in the agricultural industry. Intensive animal production involves giving livestock animals large quantities of antibiotics to promote growth and prevent infection. These uses promote the selection of antibiotic resistance in bacterial populations. The resistant bacteria from agricultural environments may be transmitted to humans, in whom they cause disease that cannot be treated by conventional antibiotics. The author reviews trends in antibiotic use in animal husbandry and agriculture in general. The development of resistance is described, along with the genetic mechanisms that create resistance and facilitate its spread among bacterial species. Particular aspects of resistance in bacterial species common to both the human population and the agrifood industry are emphasized. Control measures that might reverse the current trends are highlighted.     

Benzodiazepine use and cognitive function among community-dwelling elderly

OBJECTIVE: To evaluate the relation between benzodiazepine use and cognitive function among community-dwelling elderly. METHODS: This prospective cohort study included 2765 self-reporting subjects from the Duke Established Populations for Epidemiologic Studies of the Elderly. The subjects were cognitively intact at baseline (1986-1987) and alive at follow-up data collection 3 years later. Cognitive function was assessed with the Short Portable Mental Status Questionnaire (unimpaired versus impaired and change in score) and on the basis of the number of errors on the individual domains of the Orientation-Memory-Concentration Test. Benzodiazepine use was determined during in-home interviews and classified by dose, half-life, and duration. Covariates included demographic characteristics, health status, and health behaviors. RESULTS: After control for covariates, current users of benzodiazepine made more errors on the memory test (beta coefficient, 0.35; 95% confidence interval [CI], 0.10 to 0.61) than nonusers. Further assessment of the negative effects on memory among current users suggested a dose response in which users taking the recommended or higher dose made more errors (beta coefficient, 0.57; 95% CI, 0.26 to 0.88) and a duration response in which long-term users made more errors (beta coefficient, 0.39; 95% CI, 0.05 to 0.73) than nonusers. Users of agents with long half-lives and users of agents with short half-lives both had increased memory impairment (beta coefficient, 0.32; 95% CI, 0.01 to 0.64 and beta coefficient, 0.38; 95% CI, 0.02 to 0.75, respectively) relative to nonusers. Previous benzodiazepine use was unrelated to memory problems, and current and previous benzodiazepine use was unrelated to level of cognitive functioning as measured with the other 4 tests. CONCLUSIONS: The results suggested that current benzodiazepine use, especially in recommended or higher doses, is associated with worse memory among community-dwelling elderly.     

A local immuno-endocrine interaction may mediate rat adrenal glucocorticoid response to bacterial endotoxins

The effects of the bacterial endotoxin lipopolysaccharide (LPS) and interleukin (IL)-1beta on corticosterone secretion has been studied in vivo by employing the technique of in situ perfusion of the isolated rat left adrenal gland. Both LPS and IL-1beta dose-dependently raised corticosterone output, the response peaking at 60 and 90 min, respectively. IL-1 receptor antagonist dose-dependently reversed the effect of LPS and IL-1beta. The IL-1beta converting enzyme (ICE) inhibitor Ac-YVAD-CMK annulled the adrenal response to LPS, but did not affect that to IL-1beta. Collectively, these findings provide evidence that LPS, by enhancing adrenal production of IL-1beta, is able to evoke a sizable glucocorticoid response in the rat, thereby suggesting that local immuno-endocrine interactions may be operative in the adrenal gland of this species.     

Sequence comparison of the EcoHK31I and EaeI restriction-modification systems suggests an intergenic transfer of genetic material

The genes coding for the EcoHK31I and EaeI restriction-modification (R-M) systems from Escherichia coli strain HK31 and Enterobacter aerogenes, respectively, have been cloned and sequenced. Both ENases recognize and cleave Y/GGCCR leaving 4 nucleotide 5'-protruding ends, while the MTases modify the internal cytosine. The systems were isolated on a 2.3kb AseI fragment for EcoHK31I, and a 4.6 kb HindIII fragment for EaeI. The R and M genes of both systems converge and overlap by 14 nucleotides. Previously, we found that M.EcoHK31I consisted of two subunits, (alpha and beta), with the beta subunit being translated from an alternative open reading frame within the gene encoding the alpha subunit. Sequence comparison between the EcoHK31I and EaeI systems reveals striking similarity. The eaeIM gene also encodes alpha and beta polypeptides of 309 and 176 amino acids which share 96% and 97% identity, respectively, with those of ecoHK31IM. ecoHK31IR and eaeIR encode proteins of 318 and 315 aa, respectively, which share 92% identity but are otherwise unique in the GenBank database. The EaeI and the EcoHK31I R-M systems were found to be flanked by genes coding for integrases. It is possible that these integrases have facilitated the transfer of this system among different bacterial species.     

The role of operative arthroscopy for the diagnosis and treatment of lesions about the distal ulna

Operative arthroscopy of the wrist compliments the physical examination and radiographic imaging to improve diagnosis and treatment of lesions about the distal ulna. This article reviews the relevant anatomy, biomechanics, and classification of acute and degenerative lesions of the triangular fibrocartilage complex (TFCC). Minimally invasive diagnostic and management techniques for TFCC tears are described in detail.