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131.
Axillary shoot elongation, formation of multiple shoots and rooting of shoots were compared in nodal segment cultures of Gmelina arborea Roxb. from seedlings obtained from six provenances, over several subcultures. Provenance-dependent variation was observed with respect to these parameters. In addition, a subculture-dependent decrease was observed in multiple shoot formation and root induction. Seventy percent of the rooted plantlets were successfully hardened and transferred to soil. A transient decrease in photochemical efficiency was observed during the early stages of hardening, whereas ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) levels increased gradually as the plants acclimatized to photoautotrophic growth. 相似文献
132.
Effects of food processing on the stability of food allergens 总被引:8,自引:0,他引:8
The ubiquitous presence of allergens in the human food supply coupled with increased awareness of food allergies warrants undertaking appropriate preventive measures to protect sensitive consumers from unwanted exposure to offending food allergens. Attempts to reduce or eliminate food allergenicity through food processing have met with mixed results. The rationale for using food processing to reduce/eliminate allergenicity and limitations to using this approach are discussed. 相似文献
133.
Brockhausen I Benn M Bhat S Marone S Riley JG Montoya-Peleaz P Vlahakis JZ Paulsen H Schutzbach JS Szarek WA 《Glycoconjugate journal》2006,23(7-8):525-541
Galactosyltransferases are important enzymes for the extension of the glycan chains of glycoproteins and glycolipids, and
play critical roles in cell surface functions and in the immune system. In this work, the acceptor specificity and several
inhibitors of bovine β1,4-Gal-transferase T1 (β4GalT, EC 2.4.1.90) were studied. Series of analogs of N-acetylglucosamine (GlcNAc) and GlcNAc-carrying glycopeptides were synthesized as acceptor substrates. Modifications were
made at the 3-, 4- and 6-positions of the sugar ring of the acceptor, in the nature of the glycosidic linkage, in the aglycone
moiety and in the 2-acetamido group. The acceptor specificity studies showed that the 4-hydroxyl group of the sugar ring was
essential for β4GalT activity, but that the 3-hydroxyl could be replaced by an electronegative group. Compounds having the
anomeric β-configuration were more active than those having the α-configuration, and O-, S- and C-glycosyl compounds were all active as substrates. The aglycone was a major determinant for the rate of Gal-transfer. Derivatives
containing a 2-naphthyl aglycone were inactive as substrates although quinolinyl groups supported activity. Several compounds
having a bicyclic structure as the aglycone were found to bind to the enzyme and inhibited the transfer of Gal to control
substrates. The best small hydrophobic GlcNAc-analog inhibitor was found to be 1-thio-N-butyrylGlcNβ-(2-naphthyl) with a Ki of 0.01 mM. These studies help to delineate β4GalT–substrate interactions and will aid in the development of biologically
applicable inhibitors of the enzyme. 相似文献
134.
Periodic oscillations play a key role in cell physiology from the cell cycle to circadian clocks. The interplay of positive and negative feedback loops among genes and proteins is ubiquitous in these networks. Often, delays in a negative feedback loop and/or degradation rates are a crucial mechanism to obtain sustained oscillations. How does nature control delays and kinetic rates in feedback networks? Known mechanisms include proper selection of the number of steps composing a feedback loop and alteration of protease activity, respectively. Here, we show that a remarkably simple means to control both delays and effective kinetic rates is the employment of DNA binding sites. We illustrate this design principle on a widely studied activator-repressor clock motif, which is ubiquitous in natural systems. By suitably employing DNA target sites for the activator and/or the repressor, one can switch the clock “on” and “off” and precisely tune its period to a desired value. Our study reveals a design principle to engineer dynamic behavior in biomolecular networks, which may be largely exploited by natural systems and employed for the rational design of synthetic circuits. 相似文献
135.
Cell cultures of Pueraria tuberosa were grown in vessels of different sizes and 2L stirred tank bioreactor containing modified MS medium with morphactin (0.1 mg l?1) and 2iP (5.0 mg l?1) and 20% inoculum. Stable growth and total isoflavonoid yield of 76.6 mg l?1 were recorded in the cultures during scale up. This was in concordance with the persistent yield of the individual isoflavonoids regardless of the vessel size. 相似文献
136.
Valery L. Feigin Rita V. Krishnamurthi Suzanne Barker-Collo Kathryn M. McPherson P. Alan Barber Varsha Parag Bruce Arroll Derrick A. Bennett Martin Tobias Amy Jones Emma Witt Paul Brown Max Abbott Rohit Bhattacharjee Elaine Rush Flora Minsun Suh Alice Theadom Yogini Rathnasabapathy Braden Te Ao Priya G. Parmar Craig Anderson Ruth Bonita ARCOS IV Group 《PloS one》2015,10(8)
Background
Insufficient data exist on population-based trends in morbidity and mortality to determine the success of prevention strategies and improvements in health care delivery in stroke. The aim of this study was to determine trends in incidence and outcome (1-year mortality, 28-day case-fatality) in relation to management and risk factors for stroke in the multi-ethnic population of Auckland, New Zealand (NZ) over 30-years.Methods
Four stroke incidence population-based register studies were undertaken in adult residents (aged ≥15 years) of Auckland NZ in 1981–1982, 1991–1992, 2002–2003 and 2011–2012. All used standard World Health Organization (WHO) diagnostic criteria and multiple overlapping sources of case-ascertainment for hospitalised and non-hospitalised, fatal and non-fatal, new stroke events. Ethnicity was consistently self-identified into four major groups. Crude and age-adjusted (WHO world population standard) annual incidence and mortality with corresponding 95% confidence intervals (CI) were calculated per 100,000 people, assuming a Poisson distribution.Results
5400 new stroke patients were registered in four 12 month recruitment phases over the 30-year study period; 79% were NZ/European, 6% Māori, 8% Pacific people, and 7% were of Asian or other origin. Overall stroke incidence and 1-year mortality decreased by 23% (95% CI 5%-31%) and 62% (95% CI 36%-86%), respectively, from 1981 to 2012. Whilst stroke incidence and mortality declined across all groups in NZ from 1991, Māori and Pacific groups had the slowest rate of decline and continue to experience stroke at a significantly younger age (mean ages 60 and 62 years, respectively) compared with NZ/Europeans (mean age 75 years). There was also a decline in 28-day stroke case fatality (overall by 14%, 95% CI 11%-17%) across all ethnic groups from 1981 to 2012. However, there were significant increases in the frequencies of pre-morbid hypertension, myocardial infarction, and diabetes mellitus, but a reduction in frequency of current smoking among stroke patients.Conclusions
In this unique temporal series of studies spanning 30 years, stroke incidence, early case-fatality and 1-year mortality have declined, but ethnic disparities in risk and outcome for stroke persisted suggesting that primary stroke prevention remains crucial to reducing the burden of this disease. 相似文献137.
Diversity of the human immunodeficiency virus type 1 (HIV-1) env sequence after vertical transmission in mother-child pairs infected with HIV-1 subtype A 下载免费PDF全文
Verhofstede C Demecheleer E De Cabooter N Gaillard P Mwanyumba F Claeys P Chohan V Mandaliya K Temmerman M Plum J 《Journal of virology》2003,77(5):3050-3057
Although several virologic and immunologic factors associated with an increased risk of perinatal human immunodeficiency virus type 1 (HIV-1) transmission have been described, the mechanism of mother-to-child transmission is still unclear. More specifically, the question of whether selective pressures influence the transmission remains unanswered. The aim of this study was to assess the genetic diversity of the transmitted virus after in utero transmission and after peripartum transmission and to compare the viral heterogeneity in the child with the viral heterogeneity in the mother. To allow a very accurate characterization of the viral heterogeneity in a single sample, limiting-dilution sequencing of a 1016-bp fragment of the env gene was performed. Thirteen children were tested, including 6 with in utero infections and 7 with peripartum infections. Samples were taken the day after birth and at the ages of 6 and 14 weeks. A homogeneous virus population was seen in six (46.2%) infants, of whom two were infected in utero and four were infected peripartum. A more heterogeneous virus population was detected in seven infants (53.8%), four infected in utero and three infected peripartum. The phylogenetic trees of the mother-child pairs presented a whole range of different tree topologies and showed infection of the child by one or more maternal variants. In conclusion, after HIV-1 transmission from mother to child a heterogeneous virus population was detected in approximately one-half of the children examined. Heterogeneous virus populations were found after peripartum infection as well as after in utero infection. Phylogenetic tree topologies argue against selection processes as the major mechanism driving mother-to-child transmission but support the hypothesis that virus variability is mainly driven by the inoculum level and/or exposure time. 相似文献
138.
Vaibhav Kalamkar Mamata Joshi Varsha Borkar Sudha Srivastava Meena Kanyalkar 《Bioorganic & medicinal chemistry》2013,21(21):6753-6762
The development of novel antifungal agents with high susceptibility and increased potency can be achieved by increasing their overall lipophilicity. To enhance the lipophilicity of voriconazole, a second generation azole antifungal agent, we have synthesized its carboxylic acid ester analogues, namely p-methoxybenzoate (Vpmb), toluate (Vtol), benzoate (Vbz) and p-nitrobenzoate (Vpnb). The intermolecular interactions of these analogues with model membrane have been investigated using nuclear magnetic resonance (NMR) and differential scanning calorimetric (DSC) techniques. The results indicate varying degree of changes in the membrane bilayer’s structural architecture and physico-chemical characteristics which possibly can be correlated with the antifungal effects via fungal membrane. Rapid metabolite profiling of chemical entities using cell preparations is one of the most important steps in drug discovery. We have evaluated the effect of synthesized analogues on Candida albicans. The method involves real time 1H NMR measurement of intact cells monitoring NMR signals from fungal metabolites which gives Metabolic End Point (MEP). This is then compared with Minimum Inhibitory Concentration (MIC) determined using conventional methods. Results indicate that one of the synthesized analogues, Vpmb shows reasonably good activity. 相似文献
139.
Raveendra Melavanki Vijaya Kumar Diksha Singh Nishant Dhiman Varsha V. Koppal N. R. Patil 《Luminescence》2022,37(6):907-912
Quinoline derivative, i.e. quinilone yellow with the scientific name [sodium 2-(2,3-dihydro-1,3-dioxo-1H-inden-2-yl)quinoline-6,8-disulphonate] (SQDS) is analysed for fluorescence resonance energy transfer (FRET). Fluorescence quenching mechanism is studied by employing steady state and transient state spectroscopic measurements. Cobalt chloride is used as quencher in the present study. Linearity was observed in Stern–Volmer plots for transient state as well as steady state. This was further attributed to a mechanism of collisional quenching. Efficiency in fluorescence quenching is observed as there is a correlation between quenching constants of both transient and steady state. A significant energy transfer is reported between metal ions and SQDS molecule, according to FRET theory. Characterization results are studied and analysed. Application in the field of non-linear optics are predicted for SQDS. With Kurtz and Perry powder technique, SHG (second harmonic generation) efficiency was measured using Q-switched mode locked Nd:YAG laser emitting 1064 nm the first time with this compound. 相似文献
140.
Ya-Li Zheng Niranjana D. Amin Ya-Fang Hu Parvathi Rudrabhatla Varsha Shukla Jyotshnabala Kanungo Sashi Kesavapany Philip Grant Wayne Albers Harish C. Pant 《The Journal of biological chemistry》2010,285(44):34202-34212
The activity of Cdk5-p35 is tightly regulated in the developing and mature nervous system. Stress-induced cleavage of the activator p35 to p25 and a p10 N-terminal domain induces deregulated Cdk5 hyperactivity and perikaryal aggregations of hyperphosphorylated Tau and neurofilaments, pathogenic hallmarks in neurodegenerative diseases, such as Alzheimer disease and amyotrophic lateral sclerosis, respectively. Previously, we identified a 125-residue truncated fragment of p35 called CIP that effectively and specifically inhibited Cdk5-p25 activity and Tau hyperphosphorylation induced by Aβ peptides in vitro, in HEK293 cells, and in neuronal cells. Although these results offer a possible therapeutic approach to those neurodegenerative diseases assumed to derive from Cdk5-p25 hyperactivity and/or Aβ induced pathology, CIP is too large for successful therapeutic regimens. To identify a smaller, more effective peptide, in this study we prepared a 24-residue peptide, p5, spanning CIP residues Lys245–Ala277. p5 more effectively inhibited Cdk5-p25 activity than did CIP in vitro. In neuron cells, p5 inhibited deregulated Cdk5-p25 activity but had no effect on the activity of endogenous Cdk5-p35 or on any related endogenous cyclin-dependent kinases in HEK293 cells. Specificity of p5 inhibition in cortical neurons may depend on the p10 domain in p35, which is absent in p25. Furthermore, we have demonstrated that p5 reduced Aβ(1–42)-induced Tau hyperphosphorylation and apoptosis in cortical neurons. These results suggest that p5 peptide may be a unique and useful candidate for therapeutic studies of certain neurodegenerative diseases. 相似文献