Structure of human pancreatic lipase-related protein 2 with the lid in an open conformation

Access to the active site of pancreatic lipase (PL) is controlled by a surface loop, the lid, which normally undergoes conformational changes only upon addition of lipids or amphiphiles. Structures of PL with their lids in the open and functional conformation have required cocrystallization with amphiphiles. Here we report two crystal structures of wild-type and unglycosylated human pancreatic lipase-related protein 2 (HPLRP2) with the lid in an open conformation in the absence of amphiphiles. These structures solved independently are strikingly similar, with some residues of the lid being poorly defined in the electron-density map. The open conformation of the lid is however different from that previously observed in classical liganded PL, suggesting different kinetic properties for HPLRP2. Here we show that the HPLRP2 is directly inhibited by E600, does not present interfacial activation, and acts preferentially on substrates forming monomers or small aggregates (micelles) dispersed in solution like monoglycerides, phospholipids and galactolipids, whereas classical PL displays reverse properties and a high specificity for unsoluble substrates like triglycerides and diglycerides forming oil-in-water interfaces. These biochemical properties imply that the lid of HPLRP2 is likely to spontaneously adopt in solution the open conformation observed in the crystal structure. This open conformation generates a large cavity capable of accommodating the digalactose polar head of galactolipids, similar to that previously observed in the active site of the guinea pig PLRP2, but absent from the classical PL. Most of the structural and kinetic properties of HPLRP2 were found to be different from those of rat PLRP2, the structure of which was previously obtained with the lid in a closed conformation. Our findings illustrate the essential role of the lid in determining the substrate specificity and the mechanism of action of lipases.     

Transformation of white poplar (Populus alba L.) with a novel Arabidopsis thaliana cysteine proteinase inhibitor and analysis of insect pest resistance

Transgenic white poplar (Populus alba L.) plants expressing a novel Arabidopsis thaliana cysteine proteinase inhibitor (Atcys) gene have been produced using Agrobacterium tumefaciens-mediated gene transfer. Internodal stem segments of cv. Villafranca were co-cultivated with the EHA105 pBI-Atcys A. tumefaciens strain. Sixteen putative transgenic plant lines were regenerated from different calli with a transformation efficiency of 11%. The integration and expression of the cysteine proteinase inhibitor (Atcys) gene into the plant genome was confirmed by Southern and northern blot analyses. Papain inhibitory activity was detected in poplar transgenic tissues by means of a specific in vitro assay. Such activity was sufficient to inhibit most of the digestive proteinase activity of chrysomelid beetle (Chrysomela populi L.) and confer resistance to C. populi larvae on selected transgenic plants. A close correspondence between the inhibition of papain and resistance to poplar leaf beetle was observed in all tested transgenic lines. Our results indicate that Atcys could be succesfully employed in breeding programmes aimed at the selection of new poplar genotypes resistant to major insect pests.     

Maternal Separation Induced Alterations of Neurogenesis in the Rat Rostral Migratory Stream

1. The aim of our study was to investigate the possibility that maternal separation, an experimental model for studies of early environmental influences, has an effect on postnatal neurogenesis in neurogenic pathway—the rostral migratory stream (RMS). 2. Rat pups were subjected to maternal separation daily for 3 h, starting from the first postnatal day (P1) till P14 or P21. In the first two groups, brains were analyzed at the age of P14 and P21, respectively. In the third group, after 3 weeks of maternal separation, 1 week of normal rearing was allowed, and the brains were analyzed at P28. The controls matched the age of maternally separated animals. Dividing cells were labeled by bromodeoxyuridine; dying cells were visualized by Fluoro-Jade C and nitric oxide (NO) producing cells by NADPH-diaphorase histochemistry. 3. Quantitative analysis of proliferating cells in the RMS showed that maternal separation decreased the number of dividing cells in all experimental groups. This decrease was most prominent in the caudal part of the RMS. The amount of dying cells was increased at the end of 3 weeks of maternal separation as well as 1 week later. The number of differentiated nitrergic cells in the RMS was increased at the end of 2 or 3 weeks of maternal separation, respectively. Besides quantitative changes, maternally separated animals showed an accelerated maturation of nitrergic cells. 4. Our results indicate that an exposure of rats to adverse environmental factors in early postnatal periods may induce acute site-specific changes in the RMS neurogenesis.     

Neutrophil adhesion to endothelial cells impairs the effects of catalase and glutathione in preventing endothelial injury

We studied the effects of the CuZn superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) on endothelial permeability to ¹²⁵I-albumin after activation of neutrophils (PMN) with phorbol 12-myristate-13-acetate (PMA; 10^?8M). PMN were either in direct contact with the endothelial cell monolayer grown on a porous gelatin-coated microporous 10-μm-thick polycarbonate filter (upright system) or separated from the endothelium by a similar filter (inverted system). Transendothelial ¹²⁵I-albumin clearance rates were measured as an index of endothelial permeability. In the absence of antioxidants, activation of PMN increased transendothelial ¹²⁵I-albumin clearnace rates in both systems from 0.041 ± 0.006 μl/min (baseline) to 0.262 ± 0.18 μl/min (upright system) and from 0.063 ± 0.02 μl/min to 0.244 ± 0.06 μl/min (inverted system). PMA induced 80–90% of PMN to adhere to either gelatin-coated filters or to endothelial cells, from the basal PMN adhesion value of 5.3 ± 2.2% and 4.3 ± 1.1%, respectively. SOD, which dismutates superoxide anion to hydrogen peroxide (H₂O₂), did not alter the transendothelial ¹²⁵I-albumin clearance rates in either systm at any concerntration from 10–300 U/ml. CAT (100–1,000 U/ml) and GSH (0.5–10 mM), which remove the H₂O₂ generated during PMN activation, did not alter the increase in transendothelial ¹²⁵I-clearance rates after PMN activation in the upright system, but both agents prvented the increase in transendothelial ¹²⁵I-clearance rates in the inverted system. We conclude that PMN activation with PMA causes endothelial injury irrespective of PMN contact to the endothelial monolayer. Moreover, H₂O₂, a release product of PMN activation, is a critical mediator of PMN-dependent endothelial injury. Finally, the results indicate that CAT and GSH prevent endothelial injury only in the absence of direct PMN contact with endothelial cells, suggesting that antioxidants such as GSH and CAT are excluded from sites of PMN-endothelial contact and thus are ineffective antioxidants. © 1993 Wiley-Liss, Inc.     

Gamete Therapeutics: Recombinant Protein Adsorption by Sperm for Increasing Fertility via Artificial Insemination

A decrease in fertility can have a negative economic impact, both locally and over a broader geographical scope, and this is especially the case with regard to the cattle industry. Therefore, much interest exists in evaluating proteins that might be able to increase the fertility of sperm. Heparin binding proteins (HBPs), specifically the fertility associated antigen (FAA) and the Type-2 tissue inhibitor of metalloproteinase (TIMP-2), act to favor the capacitation and acrosome reaction and perhaps even modulate the immune system’s response toward the sperm. The objective of this research was to determine the effect on fertility of adding recombinant FAA (rFAA) and recombinant TIMP-2 (rTIMP-2) to bovine semen before cryopreservation for use in an artificial insemination (AI) program in a tropical environment. For this experiment, 100 crossbred (Bos taurus x Bos indicus) heifers were selected based on their estrus cycle, body condition score (BCS), of 4 to 6 on a scale of 1 to 9, and adequate anatomical conformation evaluated by pelvic and genital (normal) measurements. Heifers were synchronized using estradiol benzoate (EB), Celosil® (PGF2α) (Shering-Plough) and a controlled internal drug release (CIDR) device was inserted that contained progesterone. Inseminations were performed in two groups at random, 50 animals per group. The control group was inseminated with conventional semen. The treatment group was inseminated with semen containing rFAA (25 µg/mL) and rTIMP-2 (25 µg/mL). In the control group a 16% pregnancy rate was obtained versus a 40% pregnancy rate for the HBP treatment group, resulting in a significant difference (P = 0.0037). Given the results herein, one may conclude that the HBPs can increase fertility and could be an option for cattle in tropical conditions; however, one needs to consider the environment, nutrition, and the genetic interaction affecting the final result in whatever reproductive program that is implemented.     

Lomofungin,a New Antibiotic Produced by Streptomyces lomondensis sp. n

Lomofungin is a new antimicrobial agent obtained from the culture broth of Streptomyces lomondensis sp. n. UC-5022. Lomofungin is an acidic, olive-yellow, crystalline compound which inhibits, in vitro, a variety of pathogenic fungi, yeasts, and gram-positive and gram-negative bacteria.     

An evaluation of multidrug-resistant <Emphasis Type="Italic">Escherichia coli</Emphasis> isolates in urinary tract infections from Aguascalientes,Mexico: cross-sectional study

Background

Uropathogenic Escherichia coli (UPEC) are one of the main bacteria causing urinary tract infections (UTIs). The rates of UPEC with high resistance towards antibiotics and multidrug-resistant bacteria have increased dramatically in recent years and could difficult the treatment.

Methods

The aim of the study was to determine multidrug-resistant bacteria, antibiotic resistance profile, virulence traits, and genetic background of 110 E. coli isolated from community (79 isolates) and hospital-acquired (31 isolates) urinary tract infections. The plasmid-mediated quinolone resistance genes presence was also investigated. A subset of 18 isolates with a quinolone-resistance phenotype was examined for common virulence genes encoded in diarrheagenic and extra-intestinal pathogenic E. coli by a specific E. coli microarray.

Results

Female children were the group most affected by UTIs, which were mainly community-acquired. Resistance to trimethoprim–sulfamethoxazole, ampicillin, and ampicillin–sulbactam was most prevalent. A frequent occurrence of resistance toward ciprofloxacin (47.3%), levofloxacin (43.6%) and cephalosporins (27.6%) was observed. In addition, 63% of the strains were multidrug-resistant (MDR). Almost all the fluoroquinolone (FQ)-resistant strains showed MDR-phenotype. Isolates from male patients were associated to FQ-resistant and MDR-phenotype. Moreover, hospital-acquired infections were correlated to third generation cephalosporin and nitrofurantoin resistance and the presence of kpsMTII gene. Overall, fimH (71.8%) and fyuA (68.2%), had the highest prevalence as virulence genes among isolates. However, the profile of virulence genes displayed a great diversity, which included the presence of genes related to diarrheagenic E. coli. Out of 110 isolates, 25 isolates (22.7%) were positive to qnrA, 23 (20.9%) to qnrB, 7 (6.4%) to qnrS1, 7 (6.4%) to aac(6′)lb-cr, 5 (4.5%) to qnrD, and 1 (0.9%) to qnrC genes. A total of 12.7% of the isolates harbored bla_CTX-M genes, with bla_CTX-M-15 being the most prevalent.

Conclusions

Urinary tract infection due to E. coli may be difficult to treat empirically due to high resistance to commonly used antibiotics. Continuous surveillance of multidrug resistant organisms and patterns of drug resistance are needed in order to prevent treatment failure and reduce selective pressure. These findings may help choosing more suitable treatments of UTI patients in this region of Mexico.