Nitrosating activity in Escherichia coli

Nitrosation activity was measured in Escherichia coli isolates and a range of nitrite reductase (nir) mutants. Activity was only detected in intact cells and could be inhibited by a number of treatments such as sonication and osmotic shock. Aerobically-grown cells had highest nitrosation activity compared to oxygen-limited ones. Inclusion of nitrite in growth media induced high activities of nitrite reductase and for some isolates, nitrosation. Analysis of nir mutants identified two which were unable to nitrosate. This result suggested that NADH-dependent nitrite reductase was implicated either directly or indirectly in nitrosation.     

The association of human coagulation factors VIII,IXa and X with phospholipid vesicles involves both electrostatic and hydrophobic interactions

Blood coagulation factor X (FX) is converted to its active form (FXa) by a membrane bound multi-protein enzyme complex, comprised of factor VIII (FVIII), factor IXa (FIXa) and FX. Characterization of the molecular forces involved in the association of these proteins with phospholipids is crucial to understanding how these proteins bind to the lipid milieux of physiological membranes. In this report, the molecular forces involved in the association of FVIII, FIXa or FX with phospholipid vesicles (PLV) were characterized by ligand affinity chromatographic analyses. Treating FVIII-affinity columns with agents that disrupt electrostatic interactions caused elution of 15.2% of the total bound PLV, while agents that disrupt hydrophobic interactions caused elution of 84.8% of the total bound PLV. These results demonstrate that the association of PLV with FVIII is primarily hydrophobic. In contrast, the association of PLV with FIXa or FX is largely the result of electrostatic forces. This was established by observing that 71.3% and 78.9% of the total bound PLV was eluted from FIXa- and FX-affinity columns, respectively, by agents that disrupt electrostatic interactions. Of the total bound PLV, 28.7% and 21.2% were eluted from FIXa- and FX-affinity columns, respectively, by agents that disrupt hydrophobic interactions. These data demonstrate that hydrophobic forces play a heretofore unrecognized role in the association of PLV with FIXa or FX.     

Synthesis and anti-inflammatory activity of celecoxib like compounds

Nine novel 4-[3-(4-Dimethylamino-phenyl)-5-aryl-4,5-dihydro-pyrazol-1-yl]-benzenesulfonamides (2a-i) were synthesized and evaluated for their anti-inflammatory and antiproliferative activities. These compounds (2a-i) showed moderate to strong anti-inflammatory activity in carrageenan rat paw oedema test. Compounds 2b, 2d and 2g showing comparable anti-inflammatory activity to that of reference drug celecoxib were evaluated for their ulcerogenic and analgesic activities. The effect of 2b, 2d and 2g on the content of NO, TNF-α and PGE₂ in exudates from rat paw stimulated by carrageenan was also evaluated. The compound 2c showed considerable antitumor activities against all 60 human tumor cell lines with effective GI₅₀ (MG-MID) value of 3.63 µM. It exhibited maximum activity against melanoma (LOX IMVI and SK-MEL-5) cancer cell lines with GI₅₀ value less than 2 μM.     

Estimation of Individual Growth Curves by Empirically Weighted Least Squares

The simultaneous estimation of individual growth curves and a mean growth curve is accomplished by weighted least squares. A polynomial curve is fitted for each individual and the polynomial parameters are linear functions of parameters corresponding to covariates. A simple, computationally efficient variance-covariance estimator is derived. The resultant estimate is used in the weighted least squares estimation. The results are compared to empirical Bayes estimation.     

Synthesis and in vitro bioactivity of C-terminal deleted analogs of human growth hormone-releasing factor

A series of C-terminal deleted analogs of human growth hormone-releasing factor (hGRF) with either an amidated or a free carboxylic acid C-terminus were synthesized by solid phase methodology. Their capacity to release growth hormone was tested on rat anterior pituitary cells in monolayer culture. A gradual decrease of bioactivity down to 23% relative to hGRF was noted when the C-terminal amino acids were deleted to hGRF (1-34)OH. Further deletions, however, did not decrease the bioactivity because the potencies of the fragments, hGRF(1-31)NH2, (1-30)NH2 and (1-29)NH2 remained at about 50% of that of hGRF. Continual deletion of residues to hGRF(1-23)NH2, (1-22)NH2 and (1-21)NH2 still yielded bioactive fragments with full intrinsic activity despite very low potency. Only with the deletion down to hGRF(1-19)NH2 did the bioactivity completely disappear. Thus, together with the data published in a previous paper (1), the minimal biologically active core of hGRF with full intrinsic activity comprises the fragment (3-21).     

Sex-specific somatic–otolith growth relationship in two Gadidae

Otolith and somatic mass of two Gadidae ( Merlangius merlangus and Trisopterus minutus ) were compared in order to analyse the sex-specific relationship between otolith and somatic growth at age. In the present study, otolith mass appeared a reliable indicator of age in both species. Otolith growth reflected somatic growth, but the relationship between these characters varied and differed between species and sexes.     

The effects of cell density and metabolite flux on cellular dynamics

Summary Density-dependent regulation of cell growth in tissue culture is a well-known phenomenon but the mechanism of regulation remains obscure. Here we explore the effects of cell density and metabolite flux on the collective dynamics of a cell population. The intracellular dynamics are modelled by positive feedback kinetic mechanisms of the kind known to apply to yeast cells. Several experimental observations related to glycolytic oscillations are predicted and it is suggested that the general conclusions may be applicable in a broader context.     

Assessment of Optimal Selected Prognostic Factors

The identification and assessment of prognostic factors is one of the major tasks in clinical research. The assessment of one single prognostic factor can be done by recently established methods for using optimal cutpoints. Here, we suggest a method to consider an optimal selected prognostic factor from a set of prognostic factors of interest. This can be viewed as a variable selection method and is the underlying decision problem at each node of various tree building algorithms. We propose to use maximally selected statistics where the selection is defined over the set of prognostic factors and over all cutpoints in each prognostic factor. We demonstrate that it is feasible to compute the approximate null distribution. We illustrate the new variable selection test with data of the German Breast Cancer Study Group and of a small study on patients with diffuse large B‐cell lymphoma. Using the null distribution for a p‐value adjusted regression trees algorithm, we adjust for the number of variables analysed at each node as well. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)