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61.
Exoprotease activity of Leuconostoc oenos in stress conditions 总被引:1,自引:1,他引:0
Rollán Farías A.M. Strasser de Saad & M.C. Manca de Nadra 《Journal of applied microbiology》1998,85(2):219-223
Exoprotease activity during 48 h of total energy and nutrient starvation was examined in Leuconostoc oenos X2 L isolated from wine. Starved cells after 2 h of incubation at 30 °C in citrate buffer, 0.05 mmol 1−1 pH 5, showed greater extracellular proteolytic activity than at the onset of starvation. In the presence of 60 mg l−1 SO2 and 8% or 12% ethanol, the proteolytic activity was higher ; 10 mmol l−1 Ca2+ and Mg2+ produced an increase in protease activity during starvation. Glucose and 2-deoxyglucose (2-DOG) were found to repress synthesis by 80% and 100%, respectively. Cyclic adenosine 3'-5'-phosphate increased the exoprotease activity and reverted the repression by glucose and 2-DOG. De novo synthesis of proteins was required for the exoprotease activity by cells submitted to stress conditions. The absence of protease activity in the supernatant fluids from chloramphenicol-treated cells indicated that the activity is a result of deliberate release and not of passive cell lysis. 相似文献
62.
M C Maldonado A M Strasser de Saad 《Journal of industrial microbiology & biotechnology》1998,20(1):34-38
Production of pectinesterase and polygalacturonase by Aspergillus niger was studied in submerged and solid-state fermentation systems. With pectin as a sole carbon source, pectinesterase and polygalacturonase
production were four and six times higher respectively in a solid state system than in a submerged fermentation system and
required a shorter time for enzyme production. The addition of glucose increased pectinesterase and polygalacturonase production
in the solid state system but in submerged fermentation the production was markedly inhibited. A comparison of enzyme productivities
showed that those determined for pectinesterase and polygalacturonase with pectin as a carbon source were three and five times
higher by using the solid state rather than the submerged fermentation system. The productivities of the two enzymes were
affected by glucose in both fermentation systems. The membranes of cells from the solid state fermentation showed increased
levels of C18:1, C16:0 and C18:0 fatty acids. Differences in the regulation of enzyme synthesis by Aspergillus niger depended on the fermentation system, favoring the solid state over the submerged fermentation for pectinase production.
Received 12 May 1997/ Accepted in revised form 19 September 1997 相似文献
63.
It is believed that some wastes play an important role on the pollution prevention. In this paper, three different natural biomasses were investigated as biosorbent. Salsola green plant which grown at Jubail (industrial area) in KSA, it is phyto remediation plant. Salsola is metal hyper accumulation plant, it adsorbed (23.5, 25.7 mg lead per gram stem or leaf) from soil. Also it can be reused as ion exchanger for pb2+ from solution. Shrimp shell’s used for extraction of chitosan in laboratory with degree of substitution 81%. Chitosan and crosslinked carboxymethyl chitosan were investigated for pb2+ adsorption and compared with crosslinked carboxymethyl corn cob. The adsorption experiments demonstrated that the three biomasses have high adsorption capacity for pb2+, good reusability and stability for three cycles. 相似文献
64.
Saad M. Alshahrani Wenli Lu Jun-Bom Park Joseph T. Morott Bader B. Alsulays Soumyajit Majumdar Nigel Langley Karl Kolter Andreas Gryczke Michael A. Repka 《AAPS PharmSciTech》2015,16(4):824-834
The aim of this study was to evaluate a novel combination of Soluplus® and hypromellose acetate succinate (HPMCAS-HF) polymers for solubility enhancement as well as enhanced physicochemical stability of the produced amorphous solid dispersions. This was accomplished by converting the poorly water-soluble crystalline form of carbamazepine into a more soluble amorphous form within the polymeric blends. Carbamazepine (CBZ), a Biopharmaceutics Classification System class II active pharmaceutical ingredient (API) with multiple polymorphs, was utilized as a model drug. Hot-melt extrusion (HME) processing was used to prepare solid dispersions utilizing blends of polymers. Drug loading showed a significant effect on the dissolution rate of CBZ in all of the tested ratios of Soluplus® and HPMCAS-HF. CBZ was completely miscible in the polymeric blends of Soluplus® and HPMCAS-HF up to 40% drug loading. The extrudates were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and dissolution studies. DSC and XRD data confirmed the formation of amorphous solid dispersions of CBZ in the polymeric blends of Soluplus® and HPMCAS-HF. Drug loading and release of CBZ was increased with Soluplus® (when used as the primary matrix polymer) when formulations contained Soluplus® with 7–21% (w/w) HPMCAS-HF. In addition, this blend of polymers was found to be physically and chemically stable at 40°C, 75% RH over 12 months without any dissolution rate changes.KEY WORDS: carbamazepine, hot-melt extrusion, HPMCAS-HF, Soluplus®, stability 相似文献
65.
Word Sense Disambiguation (WSD) is the task of determining which sense of an ambiguous word (word with multiple meanings) is chosen in a particular use of that word, by considering its context. A sentence is considered ambiguous if it contains ambiguous word(s). Practically, any sentence that has been classified as ambiguous usually has multiple interpretations, but just one of them presents the correct interpretation. We propose an unsupervised method that exploits knowledge based approaches for word sense disambiguation using Harmony Search Algorithm (HSA) based on a Stanford dependencies generator (HSDG). The role of the dependency generator is to parse sentences to obtain their dependency relations. Whereas, the goal of using the HSA is to maximize the overall semantic similarity of the set of parsed words. HSA invokes a combination of semantic similarity and relatedness measurements, i.e., Jiang and Conrath (jcn) and an adapted Lesk algorithm, to perform the HSA fitness function. Our proposed method was experimented on benchmark datasets, which yielded results comparable to the state-of-the-art WSD methods. In order to evaluate the effectiveness of the dependency generator, we perform the same methodology without the parser, but with a window of words. The empirical results demonstrate that the proposed method is able to produce effective solutions for most instances of the datasets used. 相似文献
66.
67.
We recently showed that C low-threshold mechanoreceptors (CLTMRs) contribute to touch-evoked pain (allodynia) during experimental muscle pain. Conversely, in absence of ongoing pain, the activation of CLTMRs has been shown to correlate with a diffuse sensation of pleasant touch. In this study, we evaluated (1) the primary afferent fibre types contributing to positive (pleasant) and negative (unpleasant) affective touch and (2) the effects of tactile stimuli on tonic muscle pain by varying affective attributes and frequency parameters. Psychophysical observations were made in 10 healthy participants. Two types of test stimuli were applied: stroking stimulus using velvet or sandpaper at speeds of 0.1, 1.0 and 10.0 cm/s; focal vibrotactile stimulus at low (20 Hz) or high (200 Hz) frequency. These stimuli were applied in the normal condition (i.e. no experimental pain) and following the induction of muscle pain by infusing hypertonic saline (5%) into the tibialis anterior muscle. These observations were repeated following the conduction block of myelinated fibres by compression of sciatic nerve. In absence of muscle pain, all participants reliably linked velvet-stroking to pleasantness and sandpaper-stroking to unpleasantness (no pain). Likewise, low-frequency vibration was linked to pleasantness and high-frequency vibration to unpleasantness. During muscle pain, the application of previously pleasant stimuli resulted in overall pain relief, whereas the application of previously unpleasant stimuli resulted in overall pain intensification. These effects were significant, reproducible and persisted following the blockade of myelinated fibres. Taken together, these findings suggest the role of low-threshold C fibres in affective and pain processing. Furthermore, these observations suggest that temporal coding need not be limited to discriminative aspects of tactile processing, but may contribute to affective attributes, which in turn predispose individual responses towards excitatory or inhibitory modulation of pain. 相似文献
68.
Bárbara Santos Pires da Silva Eloísa Bonfá Júlio César Bertacini de Moraes Carla Gonçalves Schain Saad Ana Cristina de Medeiros Ribeiro Célio Roberto Gonçalves Jozélio Freire de Carvalho 《Biologicals》2010,38(5):567-569
The objective of this study was to evaluate the influence of anti-tumor necrosis factor (anti-TNF) in juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS) or psoriatic arthritis (PsA). Sixty-two patients were investigated: 7 JIA; 37 AS; and 18 PsA. Caucasian race accounted for 79% and 29% were female. Mean age was 40.4 ± 12.6years. None of the patients had a history of diabetes, and none had used oral hypoglycemic agents or insulin. Treatment was with adalimumab, infliximab and etanercept. Glucose, inflammatory markers and prednisone dose were assessed at baseline, as well as after three and six months of treatment. The mean erythrocyte sedimentation rate was significantly lower at three months and six months than at baseline (13.7 ± 18.0 and 18 ± 22.5 vs. 27.9 ± 23.4 mm; p = 0.001). At baseline, three months and six months, we found the following: mean C-reactive protein levels were comparable (22.1 ± 22.7, 14.5 ± 30.7 and 16.0 ± 23.8 mg/L, respectively; p = 0.26); mean glucose levels remained unchanged (90.8 ± 22.2 mg/dl, 89.5 ± 14.6 mg/dl and 89.8 ± 13.6 mg/dl, respectively; p = 0.91); and mean prednisone doses were low and stable (3.9 ± 4.9 mg/day, 3.7 ± 4.8 mg/day and 2.6 ± 4.0 mg/day, respectively; p = 0.23). During the first six months of treatment, anti-TNF therapy does not seem to influence glucose metabolism in JIA, AS or PsA. 相似文献
69.
El-Shahawy IS 《Memórias do Instituto Oswaldo Cruz》2010,105(8):965-969
Coprological examination of 15 Indian peacocks, Pavo cristatus, revealed the presence of a coccidium species of the genus Eimeria, which apparently represents a previously undescribed species. Sporulation is exogenous and fully developed oocysts of Eimeria pavoaegyptica sp. nov. are ellipsoidal, with a dimension of 15 (13-16) × 12 (10-12.9) microm and with a shape index of 1.25 (1-1.3). The sporulated oocysts have no micropyle but enclose one large rectangular-shaped polar granule and an oocyst residuum. The oocysts have a distinct two-layered wall, which is ~approximately1.7 microm thick. The outer layer has a smooth texture; it fills ~? of the total thickness and appears bicolored. The sporocysts are boat-shaped, of about 10 (9-11) × 4 (4-4.7) microm; their average shape-index is 2.5 microm with a small pointed Stieda body and a smooth, thin single-layered wall. No substieda body is detected. The sporocysts contain numerous, nearly uniform granular residua. The sporozoites are banana-shaped, 6 × 3 microm and each has two different-sized refractile bodies. 相似文献
70.
Fledderman EL Fujii K Ghanam RH Waki K Prevelige PE Freed EO Saad JS 《Biochemistry》2010,49(44):9551-9562
Human immunodeficiency virus type 1 (HIV-1) encodes a polypeptide called Gag that is capable of forming virus-like particles (VLPs) in vitro in the absence of other cellular or viral constituents. During the late phase of HIV-1 infection, Gag polyproteins are transported to the plasma membrane (PM) for assembly. A combination of in vivo, in vitro, and structural studies have shown that Gag targeting and assembly on the PM are mediated by specific interactions between the myristoylated matrix [myr(+)MA] domain of Gag and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. Exposure of the MA myristyl (myr) group is triggered by PI(4,5)P2 binding and is enhanced by factors that promote protein self-association. In the studies reported here, we demonstrate that myr exposure in MA is modulated by pH. Our data show that deprotonation of the His89 imidazole ring in myr(+)MA destabilizes the salt bridge formed between His89(Hδ2) and Glu12(COO-), leading to tight sequestration of the myr group and a shift in the equilibrium from trimer to monomer. Furthermore, we show that oligomerization of a Gag-like construct containing matrix-capsid is also pH-dependent. Disruption of the His?Glu salt bridge by single-amino acid substitutions greatly altered the myr-sequestered?myr-exposed equilibrium. In vivo intracellular localization data revealed that the H89G mutation retargets Gag to intracellular compartments and severely inhibits virus production. Our findings reveal that the MA domain acts as a “pH sensor” in vitro, suggesting that the effect of pH on HIV-1 Gag targeting and binding to the PM warrants investigation. 相似文献