Gestational meconium: a sign of poor neonatal prognosis

Seventy five pregnancies where the presence of antepartum meconium was detected by transabdominal amniocentesis, were compared with 224 cases showing clear amniotic fluid (A.F.). The statistical differences were analized in terms of data of anamnesis, diseases complicating pregnancy, gestational age, fetal maturity diagnosis from the A.F. study, oxytocin test, labor characteristics, perinatal mortality and neurologic morbidity during the first nine months of life. The results suggest that the presence of antepartum meconium implies an increase in fetal risk, demanding an adequate analysis of the obstetric solutions, which is discussed.     

Amino acid substitutions in the C-terminal regulatory domain disrupt allosteric effector binding to biosynthetic threonine deaminase from Escherichia coli

Shifts in the sigmoidal kinetics of allosteric threonine deaminase promoted by isoleucine and valine binding control branched chain amino acid biosynthesis in Escherichia coli. A highly conserved alpha-helix in the C-terminal regulatory domain of the tetrameric enzyme was previously implicated in effector binding and feedback inhibition. Double (447, 451) and triple (447, 451, 454) alanine replacements for the conserved amino acids leucine 447, leucine 451, and leucine 454 in this region yield enzyme variants that show increased sigmoidality in steady-state kinetics, and which are less sensitive to the allosteric modifiers isoleucine and valine. Equilibrium binding studies using fluorescence, enzyme kinetic, and calorimetric approaches indicate that the enzyme variants possess reduced affinity for isoleucine and valine, and suggest that heterotropic ligands can bind to the same site to promote their different effects. The increase in sigmoidal kinetics for the mutants relative to wild-type threonine deaminase may be attributable to the elimination of L-threonine binding to the effector sites, which activates the wild-type enzyme. Enzyme kinetic data and isotherms for active site ligand binding to the mutants can be analyzed in terms of a simple two-state model to yield values for allosteric parameters that are consistent with previous estimates based on an expanded two-state model for homotropic cooperativity for threonine deaminase.     

Chiral esters: Sex pheromone of the bagworm,Oiketicus kirbyi (Lepidoptera: Psychidae)

Gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone extract of female bagworms,Oiketicus kirbyi (Guilding), revealed five EAD-active compounds. Retention index calculations, GC-mass spectrometry in both full-scan and selected-ion monitoring modes and GC-EAD analyses of authentic standards identified the compounds as 1-methylbutyl octanoate (MBO), 1-methylbutyl nonanoate (MBN), 1-methylbutyl decanoate (MBD), 1-methylpentyl decanoate (MPD), and 1-methylbutyl dodecanoate (MBDD). Of these five chiral esters, MBD was most abundant in extracts and elicited the strongest antennal response. In field experiments in Costa Rica, (R)-MBD attractedO. kirbyi males, whereas (S)-MBD in combination with (R)-MBD inhibited response.R but notS enantiomers of MBO, MBN, and MBDD strongly synergized attraction to (R)-MBD. (S)-MBO and (S)-MBDD were inactive, whereas (S)-MBN was inhibitory. (R)-, (S)- and racemic MPD were inactive. Blends of (R)-MBD in ternary combination with either (R)-MBO and (R)-MBN or (R)-MBN and (R)-MBDD were as attractive as the five-ester blend. Five- and four-ester blends were equally attractive, suggesting redundancy of pheromone components for attraction of males. The multiple sex pheromone component blend of chiral esters inO. kirbyi may have evolved to maintain species-specific communication in bagworm communities of tropical Americas.     

Control of permanent-magnet generators applied to variable-speed wind-energy systems connected to the grid

Wind energy is a prominent area of application of variable-speed generators operating on the constant grid frequency. This paper describes the operation and control of one of these variable-speed wind generators: the direct driven permanent magnet synchronous generator (PMSG). This generator is connected to the power network by means of a fully controlled frequency converter, which consists of a pulsewidth-modulation (PWM) rectifier, an intermediate dc circuit, and a PWM inverter. The generator is controlled to obtain maximum power from the incident wind with maximum efficiency under different load conditions. Vector control of the grid-side inverter allows power factor regulation of the windmill. This paper shows the dynamic performance of the complete system. Different experimental tests in a 3-kW prototype have been carried out to verify the benefits of the proposed system.     

Nucleoside diphosphate kinase from bovine retina: purification, subcellular localization, molecular cloning, and three-dimensional structure

The biochemical and structural properties of bovine retinal nucleoside diphosphate kinase were investigated. The enzyme showed two polypeptides of approximately 17.5 and 18.5 kDa on SDS-PAGE, while isoelectric focusing revealed seven to eight proteins with a pI range of 7.4-8.2. Sedimentation equilibrium yielded a molecular mass of 96 +/- 2 kDa for the enzyme. Carbohydrate analysis revealed that both polypeptides contained Gal, Man, GlcNAc, Fuc, and GalNac saccharides. Like other nucleoside diphosphate kinases, the retinal enzyme showed substantial differences in the Km values for various di- and triphosphate nucleotides. Immunogold labeling of bovine retina revealed that the enzyme is localized on both the membranes and in the cytoplasm. Screening of a retinal cDNA library yielded full-length clones encoding two distinct isoforms (NBR-A and NBR-B). Both isoforms were overexpressed in Escherichia coli and their biochemical properties compared with retinal NDP-kinase. The structures of NBR-A and NBR-B were determined by X-ray crystallography in the presence of guanine nucleotide(s). Both isoforms are hexameric, and the fold of the monomer is similar to other nucleoside diphosphate kinase structures. The NBR-A active site contained both a cGMP and a GDP molecule each bound at half occupancy while the NBR-B active site contained only cGMP.     

AMD-Like Substrate Causes Epithelial Mesenchymal Transition in iPSC-Derived Retinal Pigment Epithelial Cells Wild Type but Not C3-Knockout

The Bruch’s membrane (BrM) is a five-layered extracellular matrix (ECM) that supports the retinal pigment epithelium (RPE). Normal age-related changes in the BrM may lead to RPE cell damage and ultimately to the onset and progression of age-related macular degeneration (AMD), which is the most common cause of visual loss among the elderly. A role for the complement system in AMD pathology has been established, but the disease mechanisms are poorly understood, which hampers the design of efficient therapies to treat millions of patients. In an effort to identify the mechanisms that lead from normal aging to pathology, we have developed a cell-based model using complement deficient human induced pluripotent stem cell (iPSC)-derived RPE cells cultured on an AMD-like ECM that mimics BrM. The data present evidence that changes in the ECM result in loss of differentiation and promote epithelial mesenchymal transition (EMT) of healthy RPE cells. This pathological process is mediated by complement activation and involves the formation of a randomly oriented collagen meshwork that drives the dedifferentiation of the RPE monolayer. Genetic ablation of complement component 3 has a protective effect against EMT but does not prevent the abnormal deposition of collagens. These findings offer new insights into the sequence of events that initiate AMD and may guide the design of efficient therapies to treat this disease with unmet medical needs.     

Anticryptococcal activity by alveolar macrophages from rats treated with cortisone acetate during different periods of time

Recently mouse models have shown that expression of costimulatory molecules such as B7-1 on tumor cells can induce tumor-specific immunity, suggesting that tumor cells modified to express costimulatory molecules can be a potential tumor vaccine. To investigate the importance of B7-1 co-stimulation in induction of autologous tumor immunity in humans, we established a renal carcinoma cell line, RCC-1, from a tumor resection and studied the patient's antitumor immune responses in vitro. The RCC-1 cell line constitutively expressed major histocompatibility complex (MHC) class I, intercellular adhesion molecule (ICAM)-1, and leukocyte function-associated antigen (LFA)-3 molecules, and MHC class II molecules were induced by interferon-gamma (IFN-gamma) treatment in vitro. However, neither RCC-1- nor IFN-gamma-treated RCC-1 cells expressed B7-1, and both failed to induce T-cell proliferative responses in mixed lymphocyte and tumor cell reaction (MLTR) assays, suggesting that the costimulatory signals provided by cell adhesion molecules such as ICAM-1 and LFA-3 were not sufficient to elicit an antitumor immune response. However, on transfection of the human B7-1 into RCC-1, these cells were able to induce a significant T-cell proliferation in MLTR assays. This T-cell response could be blocked by anti-B7 mAb treatment of the tumor cells. RCC-1B7 cells also induced the generation of tumor-specific cytolytic T lymphocytes to the parent RCC-1 cells in vitro, with little nonspecific cytolysis of an unrelated RCC line, A498, or autologous phytohemagglutinin (PHA) blasts. This specific cytotoxicity could be abrogated by anti-CD8 mAb and complement treatment. In summary, our study indicates that B7-1-CD28 interaction plays a critical role in induction of autologous tumor-specific cytotoxic T lymphocytes (CTLs) in humans, suggesting that the costimulatory molecule transfected tumor cells could be useful in expanding tumor-specific autologous CTL in vitro for adoptive tumor immunotherapy.