A genetic analysis of aromatic amino acid hydroxylases involvement in DOPA synthesis during Drosophila adult development

This study was designed to examine whether cyclosporine (CyA) acts on the endocrine system by modifying the pulsatile secretion pattern of prolactin and LH. Both pituitary-grafted and sham-operated rats were submitted to a subcutaneous vehicle or CyA (5 mg/kg) treatment daily for 10 days beginning on the day of surgery. Pituitary grafting and/or CyA administration changed the pulsatile pattern of prolactin observed in sham-operated animals. The mean values of serum prolactin were significantly increased by pituitary grafting and the treatment with CyA further increased them. The mean half-life of prolactin was significantly increased in pituitary-grafted rats and was not changed by CyA administration, although it was decreased in sham-operated rats. The frequency of prolactin pulses was significantly decreased in pituitary-grafted as compared to sham-operated controls and was not further modified by CyA administration. However, in sham-operated rats a significant decrease of this parameter was observed. Duration of the prolactin peaks was significantly increased by pituitary grafting, and was not modified by CyA administration in any of the groups studied. The absolute amplitude of the prolactin peaks was significantly increased in pituitary-grafted as compared to sham-operated animals, and the treatment with CyA further increased this parameter in both groups. Mean values of LH were significantly increased in pituitary-grafted as compared to control rats. CyA administration significantly increased LH levels in sham-operated rats and decreased them in pituitary-grafted animals. The mean half-life, the pulse frequency and the duration of LH peaks were not modified by either pituitary grafting or CyA administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determinants of the inhibitory action of purified 14-kDa phospholipases A2 on cell-free prothrombinase complex

It has been suggested (Kini, R. R., and Evans, H. J. (1987) J. Biol. Chem. 262, 14402-14407) that the anticoagulant activity of members of the 14-kDa phospholipase A2 (PLA2) family depends on the presence of basic residues within a variable surface region (residues 54-77) distinct from both the conserved catalytic machinery and surface sites mediating the antibacterial action of these enzymes (see Weiss, J., Inada, M., Elsbach, P., and Crowl, R. M. (1994) J. Biol. Chem. 269, 26331-26337). To further define the determinants of the anticoagulant activity of PLA2, we have analyzed the inhibitory effects of purified native and recombinant PLA2 on cell-free prothrombinase. Both native and recombinant wild-type pig pancreas (net charge -1) and human "secretory" PLA2 (net charge +15) produced similar dose-dependent inhibition of prothrombinase activity that was significantly less potent than a toxic PLA2 purified from snake venom. Site-specific mutations that either increased or decreased PLA2 activity toward bactericidal/permeability-increasing protein-treated Escherichia coli by up to 50-fold had no effect on antiprothrombinase activity. In contrast, substitution of Arg for Asp-59/Gly for Ser-60 in the pig PLA2 increased antiprothrombinase activity by 5-10-fold without affecting catalytic activity toward a range of phospholipid substrates or antibacterial activity. Comparison of antiprothrombinase activity of catalytically active and inactive forms of the PLA2 and under a range of phospholipid conditions revealed that the potent antiprothrombinase activity of native toxic venom PLA2 and of the D59R.S60G mutant pancreatic PLA2 reflect combined catalytic and noncatalytic actions, the latter apparently dependent on basic residues at discrete surface sites in the enzyme.     

Iterative optimization of high-affinity proteases inhibitors using phage display. 1. Plasmin

We generated a series of libraries having variants of the first Kunitz domain of human lipoprotein-associated coagulation inhibitor (LACI-D1, also known as tissue-factor pathway inhibitor-I) displayed on bacteriophage M13 as pIII-fusions. We varied LACI-DI iteratively in two regions: the P1 region (positions 10-21) and the "second loop", (positions 31-39), which together form one end of the domain. Display-phage library Lib#1 allows 31 200 amino-acid sequences in P1 region (residues 13, 16-19). Preliminary, we screened Lib#1 against human plasmin (PLA, EC 3.4.21.7) immobolized on agarose to enrich for phage displaying variants with PLA affinity. We introduced a 1600-fold increase in second-loop diversity (residues 31, 32, 34, 39) into the population of selectants from Lib#1, yielding Lib#2. Lib#2 (allowing approximately 50 million amino-acid sequences) was screened against PLA-agarose to isolate highest affinity binders. Protein EPI-P211, derived from the best isolate of Lib#2, inhibits PLA with Ki = 2 nM (at least 500-fold better than LACI-D1) and with high specificity. We used amino-acid sequences of PLA-binding selectants to design a PLA-biased library (Lib#3) which we screened against PLA. The protein EPI-P302 (derived from the best binder obtained from Lib#3) has Ki for PLA inhibition of 87 pM, which is 25-fold better than the first-round best binder and > or = 12 500-fold better than LACI-D1. EPI-P302 also shows very high specificity for PLA vs other human proteases and is resistant to inactivation by oxidants and extremes of temperature or pH. Thus, one can use selectants from one library to design target-tailored combinatorial libraries and obtain quite stable, highly specific, very high-affinity binding molecules while maintaining an essentially human framework.     

The synthesis of elastin, collagen, and glycosaminoglycans by high density primary cultures of neonatal rat aortic smooth muscle. An ultrastructural and biochemical study

Primary cultures of neonatal rat aortic smooth muscle cells inoculated at high densities (1 X 10(6) cells/25 cm2 Falcon flask) with adequate nutrient media and pH control grow rapidly and form multilayers of cells with typical "hill and valley" organization. After 10 days growth insoluble elastin formation could be visualized by phase contrast microscopy as small particles which grew rapidly to become larger irregular refractile aggregates and later coalesced to form larger aggregates and small fibres. With light and electronmicroscopy, elastin was the predominant matrix protein formed, with the "hill regions" of cultures containing abundant elastin aggregates and some collagen. In 2-week-old cultures differentiation could be observed within the cell multilayer. The older deeper cells contained more protein synthesis organelles and myofilaments and were in close association with large often coalescing elastin aggregates; compared to younger more superficial cells which contained more free polyribosomes less myofilaments, and were associated with fewer and small elastin aggregates. In older cultures this differentiation was not apparent; the cells contained many myofilaments, dense bodies, and lysosomes. Elastin aggregates and newly formed elastic fibres were abundant in the matrix. Quantitative analysis of insoluble elastin formation in the cell layer during the 4-week culture period indicated continuous biosynthesis and deposition which paralleled that of desmosine formation. Amino-acid analysis of a hot alkali insoluble residue (regarded as elastin) from 30-day-old cultures gave a profile identical with neonatal rat aortic elastin in vivo. Insoluble collagen formation in the cell layer tended to plateau after the log phase of growth was completed (10 days). Proteoglycans were found predominantly in the supernatant media. Glycosaminoglycan analysis revealed a profile of dermatan sulphate (32%), chondroitin 4-sulphate (43%), keratan and heparan sulphate (30%), with only a trace of hyaluronic acid. This study indicates that primary cultures of neonatal rat aortic smooth muscle cells remain differentiated in culture and have the unique capacity to continue to synthesize and deposit large amounts (mg) of insoluble elastin which aggregate and from elastic fibres in vitro.     

Studies on the interactions between ZDOL perfluoropolyether lubricant and the carbon overcoat of rigid magnetic media

Current high performance magnetic storage devices, i.e., hard disk drives, typically operate at elevated temperatures of nominally 45–60°C. As a consequence, understanding the thermal response of the materials used in the construction of the drive becomes imperative. In this report, we focus on the thermal behavior of a common perfluoropolyether lubricant (ZDOL) used on the carbon-overcoated, hard disk. In particular, we show that evaporative loss of this disk lubricant, as well as bonding of the lubricant to the carbon-overcoated disk, can occur at the temperatures encountered in the hard-disk drive. Surface energy measurements show that the interaction of the hydroxyl-terminated perfluoropolyether ZDOL occurs principally through the end-groups. On unannealed disks, the interaction between this “mobile” lubricant and the carbon overcoat is characterized by hydrogen bonding with the strength of these interactions being only slightly stronger than the intermolecular hydrogen bonding characteristic of bulk ZDOL. Upon annealing at temperatures in the range of 60–150°C, the ZDOL lubricant becomes “bonded” to the disk. The surface energy of the bonded lubricant is substantially lower than the mobile lubricant reflecting the increased interaction strength that occurs as a result of bonding. Since the bonded state is the lower energy state, transitions from the mobile state to the bonded state are thermodynamically favored. The kinetics of this bonding transition, as well as the kinetics of lubricant evaporation were studied as a function of temperature. Using a model of two competing reaction channels, the activation energies for both lubricant bonding and lubricant evaporation were determined to be 3.6 kcal/mole and 5.4 kcal/mole respectively. Ab initio quantum chemical modelling was used to investigate possible interaction sites on the carbon surface. Both experiment and theory indicate that interaction of the hydroxyl-terminated ZDOL to the carbon overcoat occurs via hydrogen bonding to oxygenated species on the carbon overcoat, with a binding energy of 5–8 kcal/mole. An esterification reaction between the hydroxyl end-groups of ZDOL with carboxyl groups on the carbon surface as a result of annealing is shown to be consistent with the both the surface energy data and the kinetic data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mobilization of peripheral blood stem cells in children using G-CSF after carboplatin containing myelosuppressive chemotherapy

PURPOSE: Peripheral blood stem cell (PBSC) apheresis provides an alternative to autologous marrow harvest as a source of hematologic stem cells for transplantation in children with solid tumors. PATIENTS AND METHODS: Eight children with metastatic or recurrent solid tumors underwent 27 apheresis procedures. Recovery from myelosuppressive chemotherapy occurred without continuous daily growth factor support prior to mobilization. Granulocyte colony stimulating factor (G-CSF) at 16 microgs/kg/day was used to increase stem cells in the peripheral circulation. CD 34 positive cells, mononuclear cells (MNC), and CFU-GM were measured in the apheresis products. Prior chemotherapy was examined as a clinical factor that affected PBSC yield. RESULTS: A significant correlation was found between CD 34+/kg and CFU-GM/kg of the products (r = 0.758, P < 0.001). Patients receiving cumulative doses of carboplatin over 1,600 mg/m2 produced adequate MNC (1 x 10(8)/kg) but yielded significantly less CD 34+ cells or CFU-GM than those patients receiving less carboplatin. Prior doses of etoposide and ifosfamide did not effect PBSC yield. CONCLUSIONS: The mobilization technique was well tolerated, and the products obtained produced trilineage engraftment in the patients that underwent peripheral blood stem cell transplantation. Peripheral blood stem cell apheresis in children can be optimized by selection of appropriate candidates and mobilization with G-CSF after an absence of hematopoietic growth factor support.     

An Evolutionary Model of Price Competition Among Spatially Distributed Firms

Various studies have shown the emergence of cooperative behavior in evolutionary models with repeated local interaction among spatially distributed agents. We investigate to what extent these findings generalize to evolutionary models of price competition among spatially distributed firms. We consider both one- and two-dimensional models, and we vary the amount of information firms have about competitors in their neighborhood. Our computer simulations show that the emergence of cooperative behavior depends strongly on the amount of information available to firms. Firms tend to behave most cooperatively if they have only a very limited amount of information about their competitors. We provide an intuitive explanation for this phenomenon. Our simulations further indicate that three other factors in our models, namely the accuracy of firms’ information, the probability of experimentation, and the spatial distribution of consumers, have little effect on the emergence of cooperative behavior.