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111.
112.
John V. Huddleston 《Bulletin of mathematical biology》1974,36(4):341-345
For an environmental system described by a system of nonlinear first-order differential equations, the problem of achieving specified terminal conditions in a given time with a minimum expenditure of resources is considered. The initial conditions and the minimum value are found numerically in a particular example. 相似文献
113.
Synthesis of delta-(alpha-aminoadipyl)cysteinylvaline and its role in penicillin biosynthesis. 总被引:12,自引:7,他引:5 下载免费PDF全文
P A Fawcett J J Usher J A Huddleston R C Bleaney J J Nisbet E P Abraham 《The Biochemical journal》1976,157(3):651-660
1. The stereoisomers of delta-(alpha-aminoadipyl)-L-cysteinylvaline (LLD, LLL and DLD) were synthesized from valine labelled with 3H in its methyl groups or in the alpha position. L-Cysteinyl-D-[4,4'-3H]valine was also synthesized. 2. 3H was incorporated into a compound that behaved like penicillin N when the LLD tripeptide containing either a methyl- or an alpha-labelled valine residue was incubated with a cell-free system prepared by lysis of protoplasts of Cephalosporium acremonium. 3. Incorporation was not observed under these conditions from the labelled all-L- or DLD-tripeptide, from L-cysteinyl-D-[4,4'-3H]valine, or of Penicillium chrysogenum appeared to be the LLD isomer, like that from C. acremonium. 5. These findings are discussed in relation to penicillin biosynthesis. 相似文献
114.
AS Glen D Anderson CJ Veltman PM Garvey M Nichols 《New Zealand journal of zoology.》2016,43(2):127-137
A major challenge in controlling overabundant wildlife is monitoring their populations, particularly as they decline to very low density. Camera traps and wildlife detector dogs are increasingly being used for this purpose. We compared the cost-effectiveness of these two approaches for detecting feral cats (Felis catus) on two pastoral properties in Hawke's Bay, North Island, New Zealand. One property was subject to intensive pest removal, while the other had no recent history of pest control. Camera traps and wildlife detector dogs detected cats at similar rates at both sites. The operating costs of each method were also comparable. We identify a number of advantages and disadvantages of each technique, and suggest priorities for further research. 相似文献
115.
Thomas J. Kuehl Thomas W. Davis Clayton Young Patty Nunez Melissa R. Robinson Kevin P. Huddleston Thomas J. Wincek Jose F. Pliego W. Richard Dukelow 《American journal of primatology》1999,49(2):153-164
This study was designed to measure the effects of variations in the length of pretreatment with a GnRH agonist, leuprolide acetate (LA), on subsequent follicular development and ovulation. The hypothesis was that the duration of LA suppression of pituitary function does not adversely affect ovarian response to standardized ovulation induction protocols in squirrel monkeys. The first phase determined the dose and duration of LA needed to achieve a hypogonadal state. One of two groups received daily subcutaneous injections of 50 μg of LA. The other received a single injection of 175 μg of a depot suspension of LA. Sera were assayed for estradiol (E2) and progesterone (P). E2 and P levels increased 2‐ to 5‐fold with peak levels on days 4 and 7, respectively. Suppression of steroid levels took 10 to 15 days in the LA‐treated group. Depot‐LA did not effectively suppress steroid production. After suppression, females receiving daily LA received five daily injections of hMG to stimulate follicular development. E2 and P increased in these animals. These results suggest that cycling squirrel monkeys have P‐secreting capacity throughout the cycle. This may explain how the squirrel monkey is able to accommodate both a short (4–5 day) luteal phase of their 9 day cycle and implantation from 5 to 7 days after ovulation. A second study compared exogenous follicle stimulating hormone (FSH) to endogenous gonadotropins released as a response to LA in ovulation induction. Steroid production and hCG‐induced ovulation were assessed. LA treatment was compared to a standard ovulation induction protocol by using a randomized cross‐over measures design. There were no differences in E2 and P levels in response to dosages of either LA or hMG. The ovulatory response following LA treatment was not significantly greater than that using FSH. The number of animals with unovulated, large follicles was greater on the FSH protocol (12/18) compared to the LA protocol (3/18). Thus, a single injection of a depot preparation of LA is sufficient to stimulate follicular development and ovulation when followed by an hCG injection. Based on this observation and the data on unovulated large follicles, it is suggested that the ovary responds more readily to endogenous gonadotropins released by LA than to exogenous FSH. Am. J. Primatol. 49:153–164, 1999. © 1999 Wiley‐Liss, Inc. 相似文献
116.
Mirjafari H Farragher TM Verstappen SM Yates A Bunn D Marshall T Lunt M Symmons DP Bruce IN 《Arthritis research & therapy》2011,13(5):R159
Introduction
Cardiovascular disease (CVD) is the leading cause of death in patients with inflammatory polyarthritis (IP), especially in seropositive disease. In established rheumatoid arthritis (RA), insulin resistance (IR) is increased and associated with CVD. We investigated factors associated with IR in an inception cohort of patients with early IP. 相似文献117.
Shovan Dutta Michael J. Celestine Supreet Khanal Alexis Huddleston Colin Simms Jessa Faye Arca Amlan Mitra Loree Heller Piotr J. Kraj Michel Ledizet John F. Anderson Girish Neelakanta Alvin A. Holder Hameeda Sultana 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(1):40-50
Trace elements such as copper and cobalt have been associated with virus-host interactions. However, studies to show the effect of conjugation of copper(II) or cobalt(III) metal centers to thiosemicarbazone ligand(s) derived from either food additives or mosquito repellent such as 2-acetylethiazole or citral, respectively, on Zika virus (ZIKV) or dengue virus (serotype 2; DENV2) infections have not been explored. In this study, we show that four compounds comprising of thiosemicarbazone ligand derived from 2-acetylethiazole viz., (E)-N-ethyl-2-[1-(thiazol-2-yl)ethylidene]hydrazinecarbothioamide (acetylethTSC) (compound 1), a copper(II) complex with acetylethTSC as a ligand (compound 2), a thiosemicarbazone ligand-derived from citral (compound 3) and a cobalt(III) complex with a citral-thiosemicarbazone ligand (compound 4) increased DENV2 and ZIKV replication in both mosquito C6/36 cells and human keratinocytes (HaCaT cells). Treatment of both cell lines with compounds 2 or 4 showed increased dengue viral titers at all three tested doses. Enhanced dengue viral plaque formation was also noted at the tested dose of 100 μM, suggesting higher production of infectious viral particles. Treatment with the compounds 2 or 4 enhanced ZIKV and DENV2 RNA levels in HeLa cell line and primary cultures of mouse bone marrow derived dendritic cells. Also, pre- or post treatments with conjugated compounds 2 or 4 showed higher loads of ZIKV or DENV2 envelope (E) protein in HaCaT cells. No changes in loads of E-protein were found in ZIKV-infected C6/36 cells, when compounds were treated after infection. In addition, we tested bis(1,10-phenanthroline)copper(II) chloride ([Cu(phen)2]Cl2, (compound 5) and tris(1,10-phenanthroline)cobalt(III) chloride ([Co(phen)3]Cl3, (compound 6) that also showed enhanced DENV2 loads. Also, we found that copper(II) chloride dehydrate (CuCl2·2H2O) or cobalt(II) chloride hexahydrate (CoCl2·6H2O) alone had no effects as “free” cations. Taken together, these findings suggest that use of Cu(II) or Co(III) conjugation to organic compounds, in insect repellents and/or food additives could enhance DENV2/ZIKV loads in human cells and perhaps induce pathogenesis in infected individuals or individuals pre-exposed to such conjugated complexes.
Importance
Mosquito-borne diseases are of great concern to the mankind. Use of chemicals/repellents against mosquito bites and transmission of microbes has been the topic of interest for many years. Here, we show that thiosemicarbazone ligand(s) derived from 2-acetylethiazole or citral or 1,10-phenanthroline upon conjugation with copper(II) or cobalt(III) metal centers enhances dengue virus (serotype 2; DENV2) and/or Zika virus (ZIKV) infections in mosquito, mouse and human cells. Enhanced ZIKV/DENV2 capsid mRNA or envelope protein loads were evident in mosquito cells and human keratinocytes, when treated with compounds before/after infections. Also, treatment with copper(II) or cobalt(III) conjugated compounds increased viral titers and number of plaque formations. These studies suggest that conjugation of compounds in repellents/essential oils/natural products/food additives with copper(II) or cobalt(III) metal centers may not be safe, especially in tropical and subtropical places, where several dengue infection cases and deaths are reported annually or in places with increased ZIKV caused microcephaly. 相似文献118.
119.
Lawrence SM Huddleston KA Tomiya N Nguyen N Lee YC Vann WF Coleman TA Betenbaugh MJ 《Glycoconjugate journal》2001,18(3):205-213
The addition of sialic acid residues to glycoproteins can affect important protein properties including biological activity and in vivo circulatory half-life. For sialylation to occur, the donor sugar nucleotide cytidine monophospho-sialic acid (CMP-SA) must be generated and enzymatically transferred to an acceptor oligosaccharide. However, examination of insect cells grown in serum-free medium revealed negligible native levels of the most common sialic acid nucleotide, CMP-N-acetylneuraminic acid (CMP-Neu5Ac). To increase substrate levels, the enzymes of the metabolic pathway for CMP-SA synthesis have been engineered into insect cells using the baculovirus expression system. In this study, a human CMP-sialic acid synthase cDNA was identified and found to encode a protein with 94% identity to the murine homologue. The human CMP-sialic acid synthase (Cmp-Sas) is ubiquitously expressed in human cells from multiple tissues. When expressed in insect cells using the baculovirus vector, the encoded protein is functional and localizes to the nucleus as in mammalian cells. In addition, co-expression of Cmp-Sas with the recently cloned sialic acid phosphate synthase with N-acetylmannosamine feeding yields intracellular CMP-Neu5Ac levels 30 times higher than those observed in unsupplemented CHO cells. The absence of any one of these three components abolishes CMP-Neu5Ac production in vivo. However, when N-acetylmannosamine feeding is omitted, the sugar nucleotide form of deaminated Neu5Ac, CMP-2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (CMP-KDN), is produced instead, indicating that alternative sialic acid glycoforms may eventually be possible in insect cells. The human CMP-SAS enzyme is also capable of CMP-N-glycolylneuraminic acid (CMP-Neu5Gc) synthesis when provided with the proper substrate. Engineering the CMP-SA metabolic pathway may be beneficial in various cell lines in which CMP-Neu5Ac production limits sialylation of glycoproteins or other glycans. 相似文献
120.
Rates and dates of divergence between AIDS virus nucleotide sequences 总被引:25,自引:3,他引:25