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71.
Nur Fariza Abd. RahmanMahiran Basri Mohd Basyaruddin Abdul RahmanRaja Noor Zaliha Raja Abdul Rahman Abu Bakar Salleh 《Bioresource technology》2011,102(3):2168-2176
Engkabang fat esters were produced via alcoholysis reaction between Engkabang fat and oleyl alcohol, catalyzed by Lipozyme RM IM. The reaction was carried out in a 500 ml Stirred tank reactor using heptane and hexane as solvents. Response surface methodology (RSM) based on a four-factor-five-level Central composite design (CCD) was applied to evaluate the effects of synthesis parameters, namely temperature, substrate molar ratio (oleyl alcohol: Engkabang fat), enzyme amount and impeller speed. The optimum yields of 96.2% and 91.4% were obtained for heptane and hexane at the optimum temperature of 53.9 °C, impeller speeds of 309.5 and 309.0 rpm, enzyme amounts of 4.82 and 5.65 g and substrate molar ratios of 2.94 and 3.39:1, respectively. The actual yields obtained compared well with the predicted values of 100.0% and 91.5%, respectively. Meanwhile, the properties of the esters show that they are suitable to be used as ingredient for cosmetic applications. 相似文献
72.
Low KO Mahadi NM Rahim RA Rabu A Abu Bakar FD Murad AM Illias RM 《Journal of industrial microbiology & biotechnology》2011,38(9):1587-1597
Direct transport of recombinant protein from cytosol to extracellular medium offers great advantages, such as high specific
activity and a simple purification step. This work presents an investigation on the potential of an ABC (ATP-binding cassette)
transporter system, the hemolysin transport system, for efficient protein secretion in Escherichia coli (E. coli). A higher secretory production of recombinant cyclodextrin glucanotransferase (CGTase) was achieved by a new plasmid design
and subsequently by optimization of culture conditions via central composite design. An improvement of at least fourfold extracellular
recombinant CGTase was obtained using the new plasmid design. The optimization process consisted of 20 experiments involving
six star points and six replicates at the central point. The predicted optimum culture conditions for maximum recombinant
CGTase secretion were found to be 25.76 μM IPTG, 1.0% (w/v) arabinose and 34.7°C post-induction temperature, with a predicted
extracellular CGTase activity of 68.76 U/ml. Validation of the model gave an extracellular CGTase activity of 69.15 ± 0.71 U/ml,
resulting in a 3.45-fold increase compared to the initial conditions. This corresponded to an extracellular CGTase yield of
about 0.58 mg/l. We showed that a synergistic balance of transported protein and secretory pathway is important for efficient
protein transport. In addition, we also demonstrated the first successful removal of the C-terminal secretion signal from the transported fusion protein by thrombin proteolytic cleavage. 相似文献
73.
Foraging behavior is influenced by spatial and temporal habitat heterogeniety. Here we report on within-day foraging and perceived risk of predation by the striped mouse (Rhabdomys pumilio) in a grassland savannah with wooded “islands” using giving-up densities (GUD, amount of food left behind in depletable food patches). Higher GUDs correspond to higher forging costs. GUDs were measured six times per day at 2-h intervals from paired stations along fern–grass habitat boundaries at 3 and 6 m distances from 10 wooded islands. R. pumilio's GUDs varied significantly over the course of the day with highest GUDs during the afternoon hours of 1–3 pm, and lowest between 7 and 9 am in the morning. The same pattern was consistent for both habitats (fern and grass) and distances from the wooded islands. GUDs decreased with distance from the woody islands in both fern and grass habitats and were significantly lower in the fern habitat. This activity pattern suggests that R. pumilio responds to a spectrum of spatially and temporally varying risks from a variety of predators including aerial predators that increase risk as they make use of mid-day thermals. 相似文献
74.
Chowdhury F Rahman MA Begum YA Khan AI Faruque AS Saha NC Baby NI Malek MA Kumar AR Svennerholm AM Pietroni M Cravioto A Qadri F 《PLoS neglected tropical diseases》2011,5(4):e999
Background
In Bangladesh, increases in cholera epidemics are being documented with a greater incidence and severity. The aim of this prospective study was to identify the prevalence and importance of V. cholerae O1 and enterotoxigenic Escherichia coli (ETEC) as causal agents of severe diarrhea in a high diarrhea prone urban area in Dhaka city.Methodology
Systematic surveillance was carried out on all diarrheal patients admitted from Mirpur between March 2008 to February 2010 at the ICDDR, B hospital. Stool or rectal swabs were collected from every third diarrheal patient for microbiological evaluation.Principal Findings
Of diarrheal patients attending the hospital from Mirpur, 41% suffered from severe dehydration with 39% requiring intravenous rehydration therapy. More diarrheal patients were above five years of age (64%) than those below five years of age (36%). About 60% of the patients above five years of age had severe dehydration compared with only 9% of patients under five years of age. The most prevalent pathogen isolated was Vibrio cholerae O1 (23%) followed by ETEC (11%). About 8% of cholera infection was seen in infants with the youngest children being one month of age while in the case of ETEC the rate was 11%. Of the isolated ETEC strains, the enterotoxin type were almost equally distributed; ST accounted for 31% of strains; LT/ST for 38% and LT for 31%.Conclusion
V. cholerae O1 is the major bacterial pathogen and a cause of severe cholera disease in 23% of patients from Mirpur. This represents a socioeconomic group that best reflects the major areas of high cholera burden in the country. Vaccines that can target such high risk groups in the country and the region will hopefully be able to reduce the disease morbidity and the transmission of pathogens that impact the life and health of people. 相似文献75.
Ahmed A. Morsi Lamiaa M. Shawky Tamer M. Shawky Mohamed H. Bahr Mahmoud Tawfiq Abu Alnasr Eman El Bana 《Cell biochemistry and function》2024,42(1):e3927
Gastric ulceration is a prevalent worldwide clinical presentation due to altered gastric defense mechanisms. Nonsteroidal anti-inflammatory drugs are one of the common causes of gastric ulcers mediated by the release of inflammatory mediators. The study aimed to investigate the potential protective effect of soyasaponin I (soya) against diclofenac (DIC)-induced gastric ulcer in rats and to highlight the underlying mechanisms. The experiment was conducted on 40 male Wistar albino rats, equally distributed into five groups: control, DIC-induced ulcer (9 mg/kg/d, orally, twice daily for 3 days), ulcer/soya-, ulcer/ranitidine-, and ulcer/soya/selective nuclear factor kappa B inhibitor (JSH-23)-treated groups. The doses of soya, ranitidine, and JSH were 20, 25, and 5 mg/kg/d, respectively, given orally. Gastric specimens were prepared for gene and histological study and for biochemical analysis of gastric prostaglandin E2 (PGE2), oxidative markers, and inflammatory cytokines. The gastric samples were formalin-fixed, paraffin-embedded, and subjected to hematoxylin and eosin (H&E), PAS staining, and immunohistochemical assay for identification of nuclear factor kappa B (NF-κB), cyclooxygenase-2 (COX-2), and proliferation marker (Ki67) expressions. The findings revealed decreased gastric PGE2 and altered inflammatory and oxidative markers in the ulcer model group. The H&E staining showed mucosal injury characterized by mucosal surface defects and inflammatory cell infiltrations. The polymerase chain reaction (PCR) and immunohistochemistry demonstrated an upregulation of NF-κB and COX-2 expression at gene/protein levels; meanwhile, Ki67 downregulation. The soya-treated group showed maintained biochemical, histological, and PCR findings comparable to the ranitidine-treated group. The JSH-23-treated group still showed partial gastric protection with biochemical and immunohistochemical changes. Soyasaponin I ameliorated DIC-induced gastric ulcers by targeting the COX-2 activity through modulation of NF-κB signaling. 相似文献
76.
77.
We have recently shown an essential role of the 32 amino acids C-terminus domain of IcmT of Legionella pneumophila in bacterial egress from macrophages. Mutants expressing an IcmT protein with a truncation in the C-terminus, replicate intracellularly but are defective in pore formation-mediated egress. The C-terminus domain of IcmT is the only hydrophilic domain of IcmT that is predicted to be in the cytoplasm while the rest of the protein is in the cytoplasmic membrane. In order to characterize the structure-function of the C-terminus of IcmT in the pore-forming activity and bacterial egress, we constructed 10 icmT missense mutant alleles differing by a single amino acid in the C-terminus of icmT and introduced them into the null icmT mutant. The H58Q, W69L, R71I, R79I and R86I icmT mutant alleles showed significantly lower pore-forming activity as measured by hemolysis of sRBC. The Y59S, R68L and S77L mutant alleles showed significantly lower cytopathogenicity to U937 macrophages. All 10 mutant alleles enabled the icmT null mutant to replicate intracellularly as efficiently as icmT null mutant harboring the wild-type icmT. Seven of the icmT alleles enabled the icmT null mutant to egress from infected macrophages as efficiently as icmT null mutant harboring the wild-type icmT. The other 3 substitutions conferred a partial defect in hemolysis and two of them also conferred a defect in egress from macrophages. Thus, two amino acid residues in the C-terminus of IcmT are required for both pore formation and bacterial egress. However, certain single amino acid substitutions in the C-terminus reduce the pore-forming activity when tested in vitro, but may or may not have a detectable effect on egress of L. pneumophila from U937 macrophages. 相似文献
78.
Abu Eid R Landini G 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》2005,27(4):232-240
OBJECTIVE: To compare the architectural and morphometric features of pseudoepitheliomatous hyperplasia (PEH) associated with oral granular cell tumors (GCT), normal oral mucosa and oral epithelial dysplasia. STUDY DESIGN: Quantitative comparisons between the diagnostic entities were carried out at the tissue level by estimating the fractal complexity of the epithelial connective tissue interface and at the cellular level by analyzing the morphometric features of algorithmically segmented epithelial cell areas. RESULTS: Casewise multivariate analysis showed that the fractal properties produced a correct discrimination rate of 96.4% between PEH and normal mucosa. Cellular parameters gave a 100% correct discrimination rate between PEH and mild dysplasia. Combining the fractal and cellular properties also showed 100% discrimination between PEH and normal mucosa and between PEH and mild dysplasia. CONCLUSION: The results show that PEH associated with GCT displays quantifiable morphometric features that make it differentiable from normal oral mucosa and oral epithelial dysplasia. 相似文献
79.
The Francisella tularensis subsp. novicida-containing phagosome (FCP) matures into a late endosome-like stage that acquires the late endosomal marker LAMP-2 but does not fuse to lysosomes, for the first few hours after bacterial entry. This modulation in phagosome biogenesis is followed by disruption of the phagosome and bacterial escape into the cytoplasm where they replicate. Here we examined the role of the Francisella pathogenicity island (FPI) protein IglC and its regulator MglA in the intracellular fate of F. tularensis subsp. novicida within human macrophages. We show that F. tularensis mglA and iglC mutant strains are defective for survival and replication within U937 macrophages and human monocyte-derived macrophages (hMDMs). The defect in intracellular replication of both mutants is associated with a defect in disruption of the phagosome and failure to escape into the cytoplasm. Approximately, 80-90% of the mglA and iglC mutants containing phagosomes acquire the late endosomal/lysosomal marker LAMP-2 similar to the wild-type (WT) strain. Phagosomes harbouring the mglA or iglC mutants acquire the lysosomal enzyme Cathepsin D, which is excluded from the phagosomes harbouring the WT strain. In hMDMs in which the lysosomes are preloaded with BSA-gold or Texas Red Ovalbumin, phagosomes harbouring the mglA or the iglC mutants acquire both lysosomal tracers. We conclude that the FPI protein IglC and its regulator MglA are essential for modulating phagosome biogenesis and subsequent bacterial escape into the cytoplasm. Therefore, acquisition of the FPI, within which iglC is contained, is essential for the pathogenic evolution of F. tularensis to evade lysosomal fusion within human macrophages and cause tularemia. This is the first example of specific virulence factors of F. tularensis that are essential for evasion of fusion of the FCP to lysosomes. 相似文献
80.
Binding of madindoline A to the extracellular domain of gp130 总被引:2,自引:0,他引:2
Elevated levels of IL-6 and IL-11 are associated with multiple myeloma, rheumatoid arthritis, hypercalcemia, cancer cachexia, and Castleman's disease. Madindoline A (MadA), isolated from Streptomyces nitrosporeus K93-0711, specifically inhibits the growth of IL-6- and IL-11-dependent cell lines, most likely by interfering with the homodimerization of gp130. This raises the possibility that MadA can be used as a model compound for the development of novel chemotherapeutic agents. In this report, we demonstrate that the binding of MadA to gp130 is specific and noncovalent, and displays a relatively low affinity. Furthermore, we show that the tricyclic 3a-hydroxytetrahydrofuro[2,3-b]indole (HFI) moiety of MadA alone is not sufficient for binding. Matrix-bound MadA precipitates a protein composed of the extracellular domain of gp130 fused to the Fc region of the immunoglobulin heavy chain. Binding is inhibited in a dose-dependent manner by preincubation with free MadA. The K(D) for binding of MadA to gp130 is 288 microM, as determined by surface plasmon resonance (SPR)-based biosensor analysis. The HFI portion of MadA does not bind to gp130 in either affinity precipitation or SPR analyses. Finally, MadA, but not the HFI portion, inhibits IL-6-dependent Stat3 tyrosine phosphorylation in HepG2 cells. 相似文献