Improvement of surface quality on peritectic steel slabs

Peritectic steel grades are very sensitive to microcracking along austenitic grain boundaries in continuous casting. Irsid and Aktiengesellschaft der Dillinger Hüttenwerke (DH) have combined laboratory studies and industrial trials to improve surface quality on these sensitive grades. Laboratory studies at Irsid confirmed the hypothesis that a very thin layer of ferrite along austenitic grain boundaries is detrimental for cracking and indicate that the risk of cracking decreases as soon as ferrite ratio is above 10 %. Dilatometric investigations demonstrate that there is a strong shift between thermodynamic equilibrium and beginning of γ→α phase transformation under casting conditions. Furthermore, at the slab surface, there is no cyclic transformation γ→α→γ induced by thermal cycling in front of spray nozzles and supporting rolls. DH performed trials with various cooling strategies on its new vertical caster No. 5. No cracks appear with intensive cooling whereas microcracks are present with soft cooling. These results are in agreement with laboratory studies. Intensive cooling is the standard condition at DH. With this process, microcracking is avoided for all slab formats.     

Chain transfer behavior of fractionated commercial mercaptans in emulsion polymerization of styrene

The chain transfer behavior of fractionated commercial tertiary mercaptans was investigated in batch and semicontinuous emulsion polymerization of styrene over the entire monomer conversion range. Four mercaptans were obtained by fractionation, which contained 9, 11, 12, and 13 carbons, respectively. The effect of the mercaptans was evaluated in terms of the consumption rates of the monomer and the chain transfer agents, the number average degree of polymerization, DP_n, and the polydispersity index, I, of the polymer. The batch experiments showed that the chain transfer efficiency decreases with increasing carbon number, which is due primarily to a lower diffusion rate of the chain transfer agent to the reaction sites (growing latex particles) through the aqueous phase. The partitioning ratio of the chain transfer agents between the aqueous phase and the monomer droplets also contributes, to a lesser extent, to the efficiency. The number average degree of polymerization and the polydispersity index are primarily controlled by the ratio of the mercaptan consumption rate over that of the monomer. In order to obtain a polymer with a constant DP_n and a narrow I, this ratio should be as close to unity as possible, as is the case for C₁₁. Otherwise, too high a ratio causes a severe increase in DP_n at the end of polymerization, and too low a ratio leads in the opposite direction. The semicontinuous experiments confirmed the batch results. © 1994 John Wiley & Sons, Inc.     

High-throughput solution-based medicinal library screening against human serum albumin

High-throughput screening of combinatorial libraries has evolved from studying large diverse libraries to analyzing small, structurally similar, focused libraries. This paradigm shift has generated a need for rapid screening technologies to screen both diverse and focused libraries in a simple, efficient, and inexpensive manner. We have proactively addressed these needs by developing a high-throughput, solution-based method combining size exclusion (SEC), two-dimensional liquid chromatography (2-D LC), and mass spectrometry (MS) for determining the relative binding of drug candidates in small, focused medicinal libraries against human serum albumin (HSA). Two types of libraries were used to evaluate the performance of the system. The first consisted of five diverse ligands with a wide range of hydrophobicities and whose association constants to HSA cover 3 orders of magnitude. A beta-lactam library composed of structurally similar compounds was used to further confirm the validity of the methodology. The ability to distinguish site-specific interactions of drugs competing for individual domains of the HSA receptor is also demonstrated. Comparison of chromatographic profiles of the library components before and after incubation with the receptor using multiple reaction monitoring allowed a ranking of the ligands according to their relative binding affinities. The observed rankings correlate closely with literature values of the association constants between the respective ligands and HSA. This simple, rugged methodology can screen a wide spectrum of chemical entities from combinatorial mixtures in less than 6 min.     

Parasitism of Gobius bucchichii Steindachner, 1870 (Teleostei, Gobiidae) in protected and unprotected marine environments

We collected 396 Gobius bucchichii, Steindachner, 1870 (Teleostei, Gobiidae) in and around the marine reserve of Cerbère-Banyuls, in the southeast of France, between March and July 1994. Five species of adult parasites were found: one acanthocephalan, Acanthocephaloides propinquus Dujardin, 1845 (Acanthocephala, Arhythmacanthidae); one nematode, Cucullanus sp. (Nematoda, Cucullanidae); and three species of digenetic trematodes, Helicometra sp. (Digenea, Opecoelidae), Derogenes sp. (Digenea, Hemiuridae) and Deretrema scorpaenicola Bartoli, 1990 (Digenea, Zoogonidae). Fishes collected in a protected area were on average, larger, older, had a higher percentage of regenerated scales, and harbored more parasites.     

Effectiveness of resistant starch,compared to guar gum,in depressing plasma cholesterol and enhancing fecal steroid excretion

Amylase-resistant starch (RS) represents a substrate that can be administered in substantial amounts in the diet, in contrast to gel-forming polysaccharides, such as guar gum (GG). The aim of this work was thus to compare the effects of GG and RS on cholesterol metabolism in rats adapted to 0.4% cholesterol diets, using dietary GG or RS levels (8 or 20%, respectively) that led to a similar development of fermentations, as assessed by the degree of enlargement of the cecum. The RS diet elicited a marked rise in the cecal pool of short-chain fatty acids, especially acetic and butyric acid, whereas the GG diet favored high-propionic acid fermentations. Both polysaccharides markedly altered the cholesterol excretion, from 50% of ingested cholesterol in controls, up to about 70% in rats adapted to the RS or GG diets. With these diets, the fecal excretion of bile acids was enhanced (67 and 144% with the RS and GG diets, respectively). RS and GG diets were effective in lowering plasma cholesterol (about −40%) and triglycerides (−36%). There was practically no effect of the diets on cholesterol in d>1.040 lipoproteins (high density lipoproteins), whereas RS (and to a larger extent, GG) were very effective to depress cholesterol in d<1.040 lipoproteins (especially in triglyceride-rich lipoproteins). Fermentable polysaccharides counteracted the accumulation of cholesterol in the liver, especially cholesterol esters. In parallel, liver acyl CoA:cholesterol acyltransferase was depressed in rats fed the RS or GG diets, whereas only the GG diet counteracted the downregulation of 3-hydroxy-3-methylglutaryl-CoA by cholesterol. These data suggest that RS may be practically as effective as a gel-forming gum, such as GG, on steroid excretion and on cholesterol metabolism.     

Pleuropulmonary aspergilloma: clinical spectrum and results of surgical treatment

From 1974 to 1991, 77 patients were admitted for pulmonary (55), pleural (16), or bronchial (6) aspergilloma. About 50% were asymptomatic. Sixty-three underwent operation. Pulmonary aspergillomas were operated on for therapeutic need in 26 and on principle in 18; the procedures were 28 lobar or segmental resections, 10 thoracoplasties, and 5 pleuropneumonectomies (1 patient had exploration only). Pleural aspergillosis was treated by operation on principle in 5 and for therapeutic need in 8 patients; 10 thoracoplasties, 1 attempt at pleuropneumonectomy, and 2 decortications were performed. All six bronchial lesions were operated on as a rule. Overall postoperative mortality was 9.5%. Major complications were bleeding (n = 37), pleural space problems (n = 24), respiratory failure (n = 6), and postpneumonectomy empyema (n = 4). All patients with pleural disease experienced complications. The outcome was better after lobar or segmental resection than after thoracoplasty (mortality, 6% versus 15%). Asymptomatic and nonsequellary pulmonary or bronchial aspergilloma also had an improved outcome. We conclude that operation is at low risk in pulmonary or bronchial locations in asymptomatic patients and in the absence of sequellae; the risk is high in symptomatic patients for whom operation is the only definite treatment. Pleuropneumonectomy should be avoided. Only symptomatic pleural aspergilloma should be operated on.     

A metalloproteinase inhibitor blocks the shedding of soluble cytokine receptors and processing of transmembrane cytokine precursors in human monocytic cells

A number of membrane-anchored cytokines and cytokine receptors are susceptible to yield soluble counterparts. Recently, peptide-hydroxamate metalloproteinase inhibitors have been reported to block the proteolytic processing of tumour necrosis factor (TNF)-alpha 55- and 75-kDa TNF receptors (TNF-R55 and TNF-R75), and interleukin (IL)-6R. In this report the authors studied the effect of an hydroxamate metalloproteinase inhibitor on the secretion of cytokines and the generation of cytokine soluble receptors by human myelomonoycytic cell lines and purified monocytes. Whereas secretion of cytokines lacking a transmembrane domain precursor (IL-1 alpha, IL-1 beta, IL-6 or IL-10) is either unaffected or augmented, shedding/secretion of transmembrane domain-containing cytokines and cytokine receptors [TNF-alpha, macrophage colony-stimulating factor (M-CSF), transforming growth factor (TGF)-alpha, stem cell factor (SCF), TNF-R55, TNF-R75, and IL-6R] was dramatically decreased in the presence of the metalloproteinase inhibitor. The diversity of sequences in the cleavage site of these proteins and differences found in the inhibitory concentration values suggest the existence of a metalloproteinase family displaying different substrate specificity. These results emphasize the important role of metalloproteinases as regulators of membrane expression and secretion of cytokines and cytokine receptors.     

Evaluation of nutritional status by immunologic assessment in bulimia nervosa: influence of body mass index and vomiting episodes

The nutritional status of 21 patients suffering from bulimia nervosa was evaluated by anthropometric and immunologic indexes in comparison with a control group (n = 15). In addition, the influence of body mass index (BMI; in kg/m2) values and vomiting episodes on the nutritional status of bulimic patients was assessed. Anthropometry showed no signs of malnutrition in either group, except for those patients with low weights (BMI < 19). Bulimic patients had lower lymphocyte counts than did control subjects, except for those without vomiting (NVBN). All T lymphocyte subsets tested as well as CD57 cells were lower (22% and 55%, respectively) in bulimic patients than in control subjects, but the CD19 cell subset remained unmodified. The low-weight bulimic group (LWBN) had lower CD4 cell counts than did the normal-weight (BMI > 19) bulimic group. The NVBN group had lymphocyte subpopulations similar to those in the control group, except for CD57, which was lower. The bulimic patients with vomiting had the lowest cell subset values. These results suggest a depleted nutritional status in all bulimic patients studied, even those with normal weights. The LWBN group had the most depleted nutritional status and the NVBN group was least affected at a subclinical level. CD57 can be considered a good marker of nutritional status in this syndrome because it was the only subpopulation altered in all groups.     

Cholesterol-lowering effects of guar gum: Changes in bile acid pools and intestinal reabsorption

Soluble fibers such as guar gum (GG) may exert cholesterol-lowering effects. It is generally accepted that bile acid (BA) reabsorption in portal blood is reduced, thus limiting the capacity of BA to down-regulate liver cholesterol 7α-hydroxylase, the rate-limiting enzyme of BA synthesis. In the present work, rats were adapted to fiber-free (FF) or 5% GG diets (supplemented or not with 0.25% cholesterol), to investigate various aspects of enterohepatic BA cycling. GG in the diet at a level of 5% elicited a significant lowering of plasma cholesterol during the absorptive period, in cholesterol-free (−13%) or 0.25% cholesterol (−20%) diet conditions. In rats adapted to the GG diets, the small intestinal and cecal BA pools and the ileal vein-artery difference for BA were markedly enhanced; reabsorption in the cecal vein was also enhanced in these rats. [¹⁴C]Taurocholate absorption, determined in perfused ileal segments, was not significantly different in rats adapted to the FF or GG diet, suggesting that a greater flux of BA in the ileum might support a greater ileal BA reabsorption in rats adapted to the GG diet. In contrast, capacities for [¹⁴C]cholate absorption from the cecum at pH 6.5 were higher in rats adapted to the GG diet than to the FF diet. Acidification of the bulk medium in isolated cecum (from pH 7.1 down to pH 6.5 or 5.8) or addition of 100 mM volatile fatty acids was also found to stimulate cecal [¹⁴C]cholate absorption. These factors could contribute to accelerated cecal BA absorption in rats fed the GG diet. The effects of GG on steroid fecal excretion thus appear to accompany a greater intestinal BA absorption and portal flux to the liver. These results suggest that some mechanisms invoked to explain cholesterol-lowering effect of fibers should be reconsidered.