Development of new hypoxic cell sensitizers: Amides of nitrobenzoic acid with spermidine and spermine

Summary New type hypoxic cell sensitizers, N¹, N¹⁰-bis(4-nitrobenzoyl)spermidine (1) and N¹,N¹⁴-bis(4-nitrobenzoyl)-spermine (2), have been developed. These compounds were shown to be more effective radiosensitizers to hypoxic cells than misonidazole (3).     

Inhibitory effects of spermine and spermidine on muscle calpain II

The muscle enzyme calpain II, in contrast to muscle calpain I, was markedly inhibited by millimolar concentrations of the polyamines spermine and spermidine. These compounds and the calpain inhibitor calpastatin had synergistic inhibitory effects on calpain II. These results suggest that the polyamines may have possible regulatory effects on the in vivo activity of calpain II enzymes.     

Inhibitory effects of spermine and spermidine on muscle calpain II

Summary The muscle enzyme calpain II, in contrast to muscle calpain I, was markedly inhibited by millimolar concentrations of the polyamines spermine and spermidine. These compounds and the calpain inhibitor calpastatin had synergistic inhibitory effects on calpain II. These results suggest that the polyamines may have possible regulatory effects on the in vivo activity of calpain II enzymes.     

Astrocytes in multiple sclerosis: A product of their environment

It has long been thought that astrocytes, like other glial cells, simply provide a support mechanism for neuronal function in the healthy and inflamed central nervous system (CNS). However, recent evidence suggests that astrocytes play an active and dual role in CNS inflammatory diseases such as multiple sclerosis (MS). Astrocytes not only have the ability to enhance immune responses and inhibit myelin repair, but they can also be protective and limit CNS inflammation while supporting oligodendrocyte and axonal regeneration. The particular impact of these cells on the pathogenesis and repair of an inflammatory demyelinating process is dependent upon a number of factors, including the stage of the disease, the type and microenvironment of the lesion, and the interactions with other cell types and factors that influence their activation. In this review, we summarize recent data supporting the idea that astrocytes play a complex role in the regulation of CNS autoimmunity.     

字典乘积图的点转发指数

路由选择的优劣直接影响网络通信性能的有效性.在大规模超级计算机系统中,某些元件和连线发生故障是不可避免的,故障的出现势必会对路由的选择产生影响.由于路由选择的点转发指数是用来度量网络节点的负载情况,因而它是衡量路由选择优劣的一个重要参数.本文利用图的字典乘积方法,用若干已有的小网络来构造规模较大的网络,通过分析这些小网络与所得大网络拓扑参数之间的联系,首次得到字典乘积网络点转发指数的一个紧的上界和紧的下界.     

Expulsion of the placenta from the uterus is the principal initiator for collagen degradation in mouse uterus

In unilaterally pregnant mice, collagen degradation in the non-pregnant uterine horn was not initiated by removal of the fetus only but by removal of both the fetus and placenta. The results indicate that expulsion of the placenta from the uterus is a principal factor in the initiation of the process of collagen degradation simultaneously in the whole uterus.     

Forecasting for business planning: A case study of IBM product sales

This is a case study of a closely managed product. Its purpose is to determine whether time-series methods can be appropriate for business planning. By appropriate, we mean two things: whether these methods can model and estimate the special events or features that are often present in sales data; and whether they can forecast accurately enough one, two and four quarters ahead to be useful for business planning. We use two time-series methods, Box-Jenkins modeling and Holt-Winters adaptive forecasting, to obtain forecasts of shipments of a closely managed product. We show how Box-Jenkins transfer-function models can account for the special events in the data. We develop criteria for choosing a final model which differ from the usual methods and are specifically directed towards maximizing the accuracy of next-quarter, next-half-year and next-full-year forecasts. We find that the best Box-Jenkins models give forecasts which are clearly better than those obtained from Holt-Winters forecast functions, and are also better than the judgmental forecasts of IBM's own planners. In conclusion, we judge that Box-Jenkins models can be appropriate for business planning, in particular for determining at the end of the year baseline business-as-usual annual and monthly forecasts for the next year, and in mid-year for resetting the remaining monthly forecasts.     

Norepinephrine as principal catecholamine in a specific neurone of an invertebrate (Boophilus microplus: Acarina)

Summary Norepinephrine has been identified as the principal catecholamine in individual neurons of the synganglion of an arthropod, the cattle tickBoophilus microplus. This suggests that norepinephrine may have a hitherto unsuspected major physiological role in at least one group of invertebrates.     

The molecular role of the Rothmund-Thomson-, RAPADILINO- and Baller-Gerold-gene product, RECQL4: recent progress

The RecQ family of DNA helicases is highly conserved throughout evolution and plays an important role in the maintenance of genomic stability in all organisms. Mutations in three of the five known family members in humans, BLM, WRN and RECQL4, give rise to disorders that are characterized by predisposition to cancer and premature aging, emphasizing the importance of studying the RecQ proteins and their cellular activities. Interestingly, three autosomal recessive disorders have been associated with mutations in the RECQL4 gene: Rothmund-Thomson, RAPADILINO, and Baller-Gerold syndromes, thus making RECQL4 unique within the RecQ family of DNA helicases. To date, however, the molecular function of RECQL4 and the possible cellular pathways in which it is involved remain poorly understood. Here, we present an overview of recent findings in connection with RECQL4 and try to highlight different directions the field could head, helping to clarify the role of RECQL4 in preventing tumorigenesis and maintenance of genome integrity in humans. Received 31 October 2006; received after revision 4 January 2007; accepted 5 February 2007     

Bromal,the product of reaction of aspartic acid with N-bromosuccinimide

Zusammenfassung Bromal wurde als ein Endprodukt der Reaktion zwischen Asparginsäure und N-Bromsuccinimid identifiziert und die antibakterielle Aktivität dieser Verbindung gegenüber einigen Mikroorganismen geprüft.     

Oxygenation of a dipyrromethene model for bilirubin: Formation of a singlet oxygen-like product

Summary An oxodipyrromethene model compound for bilirubin is found to undergo oxidation to a blue tetrapyrrole and a water-propentdyopent on a silica gel thin layer chromatography plate. The reaction involves ground state oxygen and requires silica gel, although the propentdyopent is an expected product from reaction with singlet oxygen.The authors wish to thank the National Science Foundation for generous support of this work. We also thank Mr.Richard Gillespie and Ms.Elizabeth Irwin for running the high resolution mass spectra.     

Carbamoyl phosphate synthetase: an amazing biochemical odyssey from substrate to product

Carbamoyl phosphate synthetase (CPS) catalyzes one of the most remarkable reactions ever described in biological chemistry, in which carbamoyl phosphate is produced from one molecule of bicarbonate, two molecules of Mg2+ ATP, and one molecule of either glutamine or ammonia. The carbamoyl phosphate so produced is utilized in the synthesis of arginine and pyrimidine nucleotides. It is also employed in the urea cycle in most terrestrial vertebrates. Due to its large size, its important metabolic role, and the fact that it is highly regulated, CPS has been the focus of intensive investigation for nearly 40 years. Numerous enzymological, biochemical, and biophysical studies by a variety of investigators have led to a quite detailed understanding of CPS. Perhaps one of the most significant advances on this topic within the last 2 years has been the successful X-ray crystallographic analysis of CPS from Escherichia coli. Quite unexpectedly, this structural investigation revealed that the three active sites on the protein are widely separated from one another. Furthermore, these active sites are connected by a molecular tunnel with a total length of approximately 100 A, suggesting that CPS utilizes this channel to facilitate the translocation of reaction intermediates from one site to another. In this review, we highlight the recent biochemical and X-ray crystallographic results that have led to a more complete understanding of this finely tuned instrument of catalysis.     

Isoelectric variants of the principal polypeptide (p 30) of different strains of murine oncornaviruses]

The major murine oncornavirus polypeptide p 30 (30,000 daltons), which bears the conventional group-specific (gs) determinants, can be separated by isoelectric focusing into four classes, with isoelectric points (pI) of 5.5, 5.9, 6.7 and 7.1. All the Moloney stocks tested have a pI 5.9 p 30, while p 30's with three to four different pI values are found to coexist in other stocks, with the pI 6.7 form predominating in Gross virus stocks.     

Effects of receptor agonists on polyamine concentrations and spermidine/spermine N1-acetyltransferase activity in rat parotid gland

The polyamine putrescine might be formed via a degradation (catalyzed by spermidine/spermine N¹-acetyltransferase, SSAT) of the higher polyamines spermidine and spermine to putrescine. The involvement of different intracellular signal pathways in the regulation of putrescine formation was studied in explants and in cultured cells of rat parotid glands by using receptor agonists that activate separate second messenger systems, and measuring their effects on the concentrations of putrescine, spermidine and spermine and on the SSAT activity. The -adrenoceptor agonist isoprenaline, which is an activator of cAMP formation, increased the putrescine concentration and stimulated the SSAT activity. Pilocarpine, a drug that activates the muscarinic receptors and thereby enhances the phosphoinositide turnover, had no effect on either the polyamine concentrations or on the SSAT activity. Epidermal growth factor (EGF), which induces activation of a protein tyrosine kinase, had no effect on the polyamine concentrations or on the SSAT activity. The adenylate cyclase activator forskolin increased the glandular levels of putrescine. Taken together, these findings suggest that increases in putrescine concentration in cultured rat parotid gland cells are accompanied by accumulation of cAMP.     

The principal toxin ofDelphinium brownii Rydb., and its mode of action

Summary Examination ofD. brownii, a stock-poison of Western Canada, revealed that the principal toxin was methyllycaconitine: a potent neuromuscular blocking agent which appears to act competitively at nicotinic receptors.We thank the University of Calgary, The National Research Council of Canada, and the Alberta Agriculture Department, for financial assistance.     

Juvenile hormone I is the principal juvenile hormone in a hemipteran insect,Riptortus clavatus

Juvenile hormone I (JH I) was identified by combined gas chromatography/mass spectrometry as the predominant JH in the hemolymph of female adults of the bean bug,Riptortus clavatus (Thunberg) (Hemiptera: Alydidae). Among JH I, II, and III, JH I was the most effective hormone for inducing the synthesis of yolk proteins in diapause adults.