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Interleukin-8 (IL-8) and closely related Glu-Leu-Arg (ELR) containing CXC chemokines, including growth-related oncogene (GRO)alpha, GRObeta, GROgamma, and epithelial cell-derived neutrophil-activating peptide-78 (ENA-78), are potent neutrophil chemotactic and activating peptides, which are proposed to be major mediators of inflammation. IL-8 activates neutrophils by binding to two distinct seven-transmembrane (7-TMR) G-protein coupled receptors CXCR1 (IL-8RA) and CXCR2 (IL-8RB), while GROalpha, GRObeta, GROgamma, and ENA-78 bind to and activate only CXCR2. A chemical lead, which selectively inhibited CXCR2 was discovered by high throughput screening and chemically optimized. SB 225002 (N-(2-hydroxy-4-nitrophenyl)-N'-(2-bromophenyl)urea) is the first reported potent and selective non-peptide inhibitor of a chemokine receptor. It is an antagonist of 125I-IL-8 binding to CXCR2 with an IC50 = 22 nM. SB 225002 showed >150-fold selectivity over CXCR1 and four other 7-TMRs tested. In vitro, SB 225002 potently inhibited human and rabbit neutrophil chemotaxis induced by both IL-8 and GROalpha. In vivo, SB 225002 selectively blocked IL-8-induced neutrophil margination in rabbits. The present findings suggest that CXCR2 is responsible for neutrophil chemotaxis and margination induced by IL-8. This selective antagonist will be a useful tool compound to define the role of CXCR2 in inflammatory diseases where neutrophils play a major role.

Camptothecin, a cytotoxic drug, is a strong inhibitor of nucleic acid synthesis in mammalian cells and a potent inducer of strand breaks in chromosomal DNA. Neither the equilibrium dialysis nor the unwinding measurement indicates any interaction between camptothecin and purified DNA. However, camptothecin induces extensive single strand DNA breaks in reactions containing purified mammalian DNA topoisomerase I. DNA breakage in vitro is immediate and reversible. Analyses of camptothecin-induced DNA breaks show that topoisomerase I is covalently linked to the 3' end of the broken DNA. In addition, camptothecin inhibits the catalytic activity of mammalian DNA topoisomerase I. We propose that camptothecin blocks the rejoining step of the breakage-reunion reaction of mammalian DNA topoisomerase I. This blockage results in the accumulation of a cleavable complex which resembles the transient intermediate proposed for eukaryotic DNA topoisomerase I. The inhibition of nucleic acid synthesis and the induction of DNA strand breaks observed in vivo may be related to the formation of this drug-induced cleavable complex.

In this study, an earlier investigation of the effects of molecular weight on fatigue crack propagation, FCP, in PVC was extended and earlier tentative conclusions were verified using samples whose molecular weight distributions were relatively constant and narrow. In the range of Mw between 6 × 104 and 2 × 105, a strong effect of M on the FCP rate per cycle (da/dN) as a function of the range in the stress intensity factor (δ K) was observed. While the apparent fracture toughness increased moderately with M, FCP rates at constant δK decreased by three orders of magnitude over the range examined. This strong dependence, which followed the empirical relationship da/dN = A eB/M δKn, implies that cyclic disentanglement is more difficult the higher M. Preliminary observations were also made on the roles of sample orientation, mean stress and thermal history. It was found that the residual orientation that survived specimen fabrication had a slight but significant effect on FCP rates and the maximum values of δ K obtainable prior to fracture (δK max). Thus the smaller the angle between the loading and orientation directions, the lower da/dN and the higher δKmax; the magnitude of the effect was greater, the lower the value of M. The mean stress also affected the FCP rate, sometimes positively and sometimes negatively, depending on the material. In contrast, little effect of prior thermal history of the FCP rate was noted. Just as an increase in temperature to above T g is known to erase the effects of aging, so did cyclic loading, a t least in this case.

The effects of molecular weight and external plasticization in PVC on fatigue crack propagation rates and fracture morphology were studied. Results were interpreted in terms of the stability of the networks in crazes ahead of the crack.

Methidiumpropyl-EDTA . iron(II) [MPE . Fe (II)] cleaves double-helical DNA with considerably lower sequence specificity than micrococcal nuclease. Moreover, digestions with MPE . Fe(II) can be performed in the presence of certain metal chelators, which will minimize the action of many endogenous nucleases. Because of these properties MPE . Fe(II) would appear to be a superior tool for probing chromatin structure. We have compared the patterns generated from the 1.688 g/cm3 complex satellite, 5S ribosomal RNA, and histone gene sequences of Drosophila melanogaster chromatin and protein-free DNA by MPE . Fe(II) and micrococcal nuclease cleavage. MPE . Fe(II) at low concentrations recognizes the nucleosome array, efficiently introducing a regular series of single-stranded (and some double-stranded) cleavages in chromatin DNA. Subsequent S1 nuclease digestion of the purified DNA produces a typical extended oligonucleosome pattern, with a repeating unit of ca. 190 base pairs. Under suitable conditions, relatively little other nicking is observed. Unlike micrococcal nuclease, which has a noticeable sequence preference in introducing cleavages, MPE . Fe(II) cleaves protein-free tandemly repetitive satellite and 5S DNA sequences in a near-random fashion. The spacing of cleavage sites in chromatin, however, bears a direct relationship to the length of the respective sequence repeats. In the case of the histone gene sequences a faint, but detectable, MPE . Fe(II) cleavage pattern is observed on DNA, in some regions similar to and in some regions different from the strong chromatin-specified pattern. The results indicate that MPE . Fe(II) will be very useful in the analysis of chromatin structure.

A camptothecin-resistant subline of P388 leukemia (P388/CPT) was developed by repeated transplantation of P388 cells in mice treated with therapeutic doses of camptothecin. In mice bearing the resistant tumor, a maximally tolerated dose of camptothecin produced no net reduction in tumor cell burden, in contrast to a 5-log cell kill in the parental P388 (P388/S). The IC50 of camptothecin, as determined by colony formation assays of cultured cells, was 8 times greater for the cloned P388/CPT cell line than for P388/S. P388/CPT cells were not cross-resistant to other antineoplastic agents, including topoisomerase II inhibitors. The type I topoisomerases purified from P388/CPT and P388/S cells were identical with respect to molecular weight, specific activity, in vitro camptothecin sensitivity, and DNA cleavage specificity. Camptothecin induced fewer protein-associated DNA single-strand breaks in the resistant cells than in the wild-type P388 cells. Topoisomerase I mRNA, immunoreactivity, and extractable enzymatic activity were 2-4 times lower for P388/CPT cells than for P388/S cells. As resistance to camptothecin developed, topoisomerase I extractable activity decreased, concomitant with an increase in topoisomerase II extractable activity. Furthermore, the appearance of camptothecin resistance was associated with specific rearrangements of the topoisomerase I gene. These results suggest that development of resistance to inhibitors of topoisomerase I can occur by down-regulation of the target enzyme, thus reducing the production of lethal enzyme-mediated DNA damage. The enhanced topoisomerase II activity in these cells suggests that resistance to camptothecin may be overcome by co-treatment with topoisomerase II inhibitors.

We report a direct technique for determining the binding sites of small molecules on naturally occurring heterogeneous DNA. Methidiumpropyl-EDTA.Fe(II) [MPE.Fe(II) cleaves double helical DNA with low sequence specificity. Using a combination of MPE.Fe(II) cleavage of drug-protected DNA fragments and Maxam-Gilbert gel methods of sequence analysis, we have determined the preferred binding sites on a Rsa I-EcoRI restriction fragment from pBR322 for the intercalator actinomycin D and the minor groove binders netropsin and distamycin A. Netropsin and distamycin A gave identical DNA cleavage-inhibition patterns and bound preferentially to A+T-rich regions with a minimal protected site of four base pairs. We were able to observe the effect of increasing concentration on site selection by netropsin and distamycin A. Actinomycin D afforded a completely different cleavage-inhibition pattern, with 4- to 16-base-pair-long protected regions centered around one or more G.C base pairs.

The anisotropy of fatigue crack propagation in hot rolled steel plate was studied for three orientations, viz., crack arrester, crack divider, and short transverse. The dependence of crack growth rate on stress intensity factor was shown to be sensitive to the microconstituents present and their orientation relative to the fracture plane and direction. Generally, this dependence increased as the material toughness decreased and when the mechanical fibering was parallel to the facture plane and direction. The macroscopic growth rates, were considered as the summation of several macroscopic mechanisms, including striation formation and inclusion-matrix fracture. The data show that striation spacing was independent of orientation and that the fracture of inclusions was primarily responsible for the observed crack growth anisotropy.

The Mycobacteria. By Colin Ratledge, B.Sc.Tech., Ph.D., F.R.I.C.; Patterns of Progress;1977. England: Meadowfield Press Ltd. 8″ × 5½″, pp. 138, with diagrams. Price: $US9.60. Biological Amplification Systems in Immunology. Edited by Noorbibi K. Day and Robert A. Good; Comprehensive Immunology, No. 2;1977. London, New York: Plenum Publishing Corporation. 10″ × 7″, pp. 342, with diagrams. Price: $US35.40. The Biochemistry of Adenosyl methionine: Proceedings of an International Symposium on The Biochemistry of Adenosylmethionine, sponsored by the Accademia Nazionale dei Lincei, held in Rome, Italy. May 21‐26. 1974. Edited by Francesco Salvatore, Ernest Borek, Vincenzo Zappia, Howard Guy Williams‐Ashman and Fritz Schlenk; 1977. New York: Columbia University Press; Sydney: Australia and New Zealand Book Co. Pty Ltd. 9″ × 5¾″, pp. 604, with diagrams. Price: $67.50. Goldrush Doctors at Ballaarat. By Keith Macrae Bowden, 1977. Melbourne: Published by Author. 11¼″ × 8½″, pp. 126, with illustrations. Price: Not stated. Cancer: A Comprehensive Treatise‐‐‐5: Chemotherapy. Edited by Frederick F. Becker; 1977. London, New York: Plenum Publishing Corporation. 10″ × 7″, pp. 688, with diagrams. Price: $US51.00. Mechanical Support of the Failing Heart and Lungs. Edited by David Bregman, M.D.; 1977. New York: Appleton‐Century‐Crofts; Sydney: Prentice Hall of Australia Pty Ltd. 9″ × 6″, pp. 224, with illustrations. Price: $33.75. Clinical Reproductive Neuroendocrinology: 6th International Seminar on Reproductive Physiology and Sexual Endocrinology, Brussels, 1976. Edited by P. O. Hubinont, M. L'Hermite and C. Robyn; 1977. Basel: S. Karger; Sydney: Australasian Drug Information Services Pty Ltd., 24 cm × 16½ cm, pp. 296, with illustrations. Price: Sw.Fr.116.00. Dermatoglyphics in Medical Disorders. By Blanka Schaumann and Milton Alter; 1976. New York, Berlin: Springer‐Verlag; Mitcham, Victoria: D. A. Book Depot Pty Ltd. 9″ × 6″, pp. 270, with illustrations. Price: $25.30. The Biology of DNA Tumour Viruses. Edited by Samuel Schiminovich; Milestones in Current Research. Volume 1: 1976. New York, London: Plenum Press. 10″ × 6½″, pp. 284, with illustrations. Price: $US30.00. The Metabolic Consequences of Chronic Renal Failure. By Michael R. Wills, R.D., M.D., M.R.C.P., M.R.C.Path.; 1978, second edition. Buckinghamshire: H.M. & M. Publishers. 23¼ cm × 15¼ cm, pp. 224, with diagrams. Price: £10.50. Remembering Henry. Edited by Stephen Lock and Heather Windle; 1977. London: British Medical Association. 8½″ × 5¼″, pp. 178, with illustrations. Price: $US7.50 and £3.00. Lectures on Forensic Medicine and Pathology. By Vernon D. Plueckhahn, E.D., M.D. (Adel.), F.R.A.C.P., F.R.C.P.A., F.R.C.Path., F.A.A.C.B., M.I.A.C.; second edition, 1978. Melbourne: University of Melbourne, 29¼ cm × 20¼ cm, pp. 298. Price: $3.00. Vitreous Surgery and Advances in Fundus Diagnosis and Treatment. Edited by H. MacKenzie Freeman, M.D., Tatsuo Hirose, M.D. and Charles L. Schepens, M.D.; 1977. New York: Appleton‐Century‐Crofts; Sydney: Prentice Hall of Australia Pty Ltd. 10″ × 7″, pp. 701, with illustrations. Price: $84.50. Scientific Foundations of Ophthalmology. Edited by Edward S. Perkins and David W. Hill; 1977. London: William Heinemann Books Ltd, 28½ cm × 22¼ cm. Price: £25.00.

Abstract: In an effort to more fully understand fatigue crack propagation in composite materials, tension-tension fatigue studies of the Ni−Ni3Nb eutectic composite were conducted. This composite displayed excellent fatigue resistance in a notched configuration by exhibiting an endurance limit of 55 pct of the 108.7 ksi smooth bar tensile strength. Under high stress-low cycle fatigue conditions, the fatigue resistance of the composite was controlled by the {112} twinning and subsequent twin boundary fracture of the Ni3Nb phase. However, under low stress-high cycle fatigue conditions, Stage I crack propagation was observed in the nickel matrix. It was concluded that the nickel matrix controls the high cycle fatigue resistance of the composite. The fatigue behavior of the Ni−Ni3Nb eutectic composite was compared with that of the Al−Al3Ni composite. The similarity in the operative crack growth mechanisms in these two composites suggests a trend which may apply to all composites.

Abstract: To understand the mechanical behavior of the Ni−Ni3Nb eutectic composite, it was necessary to determine the operative deformation and fracture mechanisms in the Ni3Nb intermetallic phase. It was found that Ni3Nb deforms primarily by twinning along {112} planes and {011} planes when tension and compression, respectively, are applied parallel to the [100] growth direction. The {112} twins were observed to serve as crack nucleation sites with cracks forming along the twin boundaries. The monotonic response of the Ni−Ni3Nb eutectic composite was investigated with tension and compression tests, metallography, and electron fractography. Room temperature tensile testing of the Ni−Ni3Nb composite revealed this material to be capable of sustaining tensile strains in excess of 11 pct. This large composite ductility was associated with extensive {112} twinning of the Ni3Nb lamellae and subsequent twin boundary cracking. When amassed in sufficient numbers in a given cross-section, these {112} twin boundary fissures initiated composite rupture. The room temperature ultimate tensile and compressive strengths of the alloy were found to be 109 and 235 ksi, respectively.

N,N‘-Diarylureas were prepared, and the structure−activity relationship relative to the CXCR2 receptor was examined. This led to the identification of a potent and highly selective CXCR2 antagonist, which in addition was shown to be functionally active both in vitro against human neutrophils and in vivo in rabbit models of ear edema and neutropenia.