To simultaneously take into account the Biot-flow mechanism, the squirt-flow mechanism, and the frame-viscoelasticity mechanism, a generalized viscoelastic BISQ (Biot/squirt) model is developed for wave propagation ...To simultaneously take into account the Biot-flow mechanism, the squirt-flow mechanism, and the frame-viscoelasticity mechanism, a generalized viscoelastic BISQ (Biot/squirt) model is developed for wave propagation in clay-bearing sandstones based on Dvorkin's elastic BISQ model. The present model is extended to a wide range of permeabilities (k 〉 0.05 mD) by introducing a dimensionless correction factor for viscoelastic parameters, defined as a function of the permeability and the clay content. We describe the frame's stress-strain relationship of the clay-bearing sandstones by the differential constitutive equations of generalized viscoelasticity and then derive the viscoelastic-wave dynamic equations. With the assumption of a plane-wave solution, we finally yield the phase velocities and the attenuation coefficients by solving the dynamic wave equations in the frequency and wave number domain. The comparison of numerical results and experimental data shows that the generalized viscoelastic BISQ model is applicable for modeling the wave propagation in most of the sandstones mainly bearing kaolinite clay.展开更多
Aim Ciprofloxacin polylactic acid microspheres (CFX-PLA-MS) were preparedusing solvent evaporation method from a solid-in-oil-in-water emulsion system. Methods Orthogonalexperiment was used to optimize the method of C...Aim Ciprofloxacin polylactic acid microspheres (CFX-PLA-MS) were preparedusing solvent evaporation method from a solid-in-oil-in-water emulsion system. Methods Orthogonalexperiment was used to optimize the method of CFX-PLA-MS preparation. Microspheres werecharacterized in terms of morphology, size, encapsulation efficiency, drug loading and in vitro drugrelease. Results The physical state of CFX-PLA-MS was determined by scanning electron microscopy(SEM) and differential scanning calorimetry (DSC) . Microspheres formed were spherical with smoothsurfaces. Drug was enveloped in microspheres without mixing physically with PLA. The averageparticle size was 280.80 ± 0.15 μm, with over 90% of microspheres falling in the range of 250 -390 μm. The encapsulation efficiency was 65.8% ± 0.58% and the drug loading was 34.1% ± 0.51% .In vitro release study revealed a profile of sustained release of Ciprofloxacin from CFX-PLA-MS. Theaccumulated release percentage and half-life (T_(1/2) of Ciprofloxacin microspheres were 84.0% in53.2 h, and 31.9 h, respectively. Higuchi equation was Q= -0.0043 + 0.003 9 t^(1/2), r = 0.9941.Conclusion Ciprofloxacin microspheres have been successfully prepared and sustained release of CFXfrom microspheres is achieved.展开更多
Chylothorax is an uncommon disease where fatty fluid accumulates within the chest cavity. Conservative manage- ment, including repeated thoracentesis or pleurodesis, seems to be suitable to most cases. Herein, we pres...Chylothorax is an uncommon disease where fatty fluid accumulates within the chest cavity. Conservative manage- ment, including repeated thoracentesis or pleurodesis, seems to be suitable to most cases. Herein, we present a case of efficacious pleurodesis by intrapleural injection of Sapylin, a streptococcus preparation, for the treatment of chylothorax. A 52-year-old non-smoking female farmer was diagnosed as idiopathic chylothorax after we ruled out possible causes including chest trauma, lymphoma, lung cancer, filariasis, tuberculosis, and etc. Two-time intra-thoracic injection of 3 Klinische Einheit (KE) Sapylin achieved rapid and effective control of chylothorax with no severe side effects. Sapylin may facilitate pleurodesis by producing a strong inflammatory response.展开更多
The limitation of iron(Fe)makes the North Pacific a typically high-nitrate,low-chlorophyll(HNLC)region in comparison with other oceanic regions of the world.Iron inputs from land via river discharge and atmospheric du...The limitation of iron(Fe)makes the North Pacific a typically high-nitrate,low-chlorophyll(HNLC)region in comparison with other oceanic regions of the world.Iron inputs from land via river discharge and atmospheric dust deposition are the primary processes introducing Fe into the ocean.Also,subsequent physical processes are crucial in transporting biologically available Fe into the upper ocean.As anthropogenic dust increases,the Fe from anthropogenic activities is expected to become more important in terms of impacting marine ecosystems.To investigate the Fe cycle and its impact on ecosystems,a project entitled‘The sources and transport of Fe in the North Pacific and its impact on marine ecosystems’has been funded by the National Natural Science Foundation of China.The project will focus on three major scientific questions:(1)What are the major sources of Fe in the North Pacific?(2)What is the influence of the Fe-binding ligand cycle on marine ecosystems?(3)What is the likely influence of global change in the future?The distribution of Fe and its corresponding impact on the marine ecosystem in current and future environmental conditions will be investigated.The results of the project are expected to improve our understanding of the marine ecosystem in the North Pacific.展开更多
Endosymbionts influence many aspects of their hosts’ health conditions, including physiology, development, immunity, metabolism, etc. Tree shrews(Tupaia belangeri chinensis) have attracted increasing attention in mod...Endosymbionts influence many aspects of their hosts’ health conditions, including physiology, development, immunity, metabolism, etc. Tree shrews(Tupaia belangeri chinensis) have attracted increasing attention in modeling human diseases and therapeutic responses due to their close relationship with primates. To clarify the situation of symbiotic bacteria from their body surface, oral cavity, and anus, 12 wild and 12 the third generation of captive tree shrews were examined. Based on morphological and cultural characteristics, physiological and biochemical tests, as well as the 16 S rDNA full sequence analysis, 12 bacteria strains were isolated and identified from the wild tree shrews: body surface: Bacillus subtilis(detection rate 42%), Pseudomonas aeruginosa(25%), Staphlococcus aureus(33%), S. Epidermidis(75%), Micrococcus luteus(25%), Kurthia gibsonii(17%); oral cavity: Neisseria mucosa(58%), Streptococcus pneumonia(17%); anus: Enterococcus faecalis(17%), Lactococus lactis(33%), Escherichia coli(92%), Salmonella typhosa(17%); whereas, four were indentified from the third generation captive tree shrews: body surface: S. epidermidis(75%); oral cavity: N.mucosa(67%); anus: L. lactis(33%), E. coli(100%). These results indicate that S. epidermidis, N. mucosa, L. lactis and E. coli were major bacteria in tree shrews, whereas, S. aureus, M. luteus, K. gibsonii, E. faecalis and S. typhosa were species-specific flora. This study facilitates the future use of tree shrews as a standard experimental animal and improves our understanding of the relationship between endosymbionts and their hosts.展开更多
Geotechnical properties of sedimentary rocks exposed along upper Egypt-Red Sea road were investigated to evaluate their geotechnical behavior. One of the most important aims of this work was to determine the engineeri...Geotechnical properties of sedimentary rocks exposed along upper Egypt-Red Sea road were investigated to evaluate their geotechnical behavior. One of the most important aims of this work was to determine the engineering problems affected on the road due to the geotechnical behavior of the studied sedimentary rocks and to suggest the suitable solution. Specific weight, unconfined compressive strength, slaking durability and free swelling were measured. The results showed that the studied crystalline limestone, marly limestone and Issawia limestone had higher unconfined compressive strength values ranging from 34,184.00 kN/m2 to 42,602.00 kN/m2 and the studied shale, siltstone and coral reef had lower values ranging from 3,689.00 kN/m2 to 6,933.00 kN/m2. The results showed also that the studied shale, siltstone and mudstone had fast to very fast slaking rate and their slaking amount described as low to medium after Gamble's slake durability classification. Replacement and/or chemical stabilization (using lime and/or cement kiln dust) of the expansive sedimentary rocks (shale and mudstone) were recommended to reduce the swelling. Geophysical investigations including shallow seismic, microgravity and GPR (ground penetrating radar) were recommended to scan the sub-grade of the road at El Maaza plateau to determine possible other caves and large voids under the road to avoid its collapse.展开更多
Representativity of biota in the biosphere also have similar significance in the lithosphere after their death. Recently, taphonomic representation of biota in the lithosphere has been widely used for minimizing the b...Representativity of biota in the biosphere also have similar significance in the lithosphere after their death. Recently, taphonomic representation of biota in the lithosphere has been widely used for minimizing the biases in palaeo-environmental reconstructions including global climate change. In September 2001, a sediment trap was installed at the central area of the Loch Coire Fionnaraich (LCFR), a small, oligotrophic mountain loch in northwest Scotland for a taphonomic study of cladoceran zooplankton. The trap was emptied on a seasonal basis, where an average 0.14 g dry material was recovered in each season, January, May and August 2002 respectively. A sediment core was also taken from near the sediment trap location. The top 0.5 cm section, the 'core' was used for a comparative study with the trap sediment samples. The planktonic Cladocera consisted of Bosmina coregoni and appeared to have excellent preservation in the trap assemblages. Moreover, some common littoral Cladocera such as Alonella excisa and Aloha guttata appear to be less well preserved in the fossil assemblages. Large littoral taxa such as Eurycercus lamellatus and Aloha quadrangularis were rare in the trap but relatively common and well preserved in the sediment-water interface. It is suggested that taphonomic processes play a dominant role on deposition of fossil remains of Cladocera and caution should be taken while inferring the past environmental changes whilst using fossil assemblages recovered from the lake centre as a representation of the entire cladoceran community in the lake.展开更多
Mine rocky desertification is another type of rocky desertification which coexists with Karst rocky desertification, suggested firstly by professor SONG Jian-bo, Guizhou University. Mine rocky desertification is a pro...Mine rocky desertification is another type of rocky desertification which coexists with Karst rocky desertification, suggested firstly by professor SONG Jian-bo, Guizhou University. Mine rocky desertification is a process and result that the earth's surface is similar to desert landscapes after rock is exposed gradually, owing to mine wastes discharged at will which consist of waste residue, waste liquid and waste gas. On the basis of introducing Karst rocky desertification simply, we clarify the concept of Mine rocky desertification systemically, analyze its danger and compare the differences between Mine rocky desertification and Karst rocky desertification. Finally, we make preliminary discussion on the study significance of comprehensive treatment of Mine rocky desertification展开更多
Multi-drug resistant microbial infections caused by Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi represent a critical public health issue worldwide. Plant-derived agents are cre...Multi-drug resistant microbial infections caused by Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi represent a critical public health issue worldwide. Plant-derived agents are credible sources for search and development of alternative antimicrobials to fight these infections. This study describes the in-vitro antibacterial activity of plants extracts from 15 medicinal plants of the Cameroonian pharmacopeia against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi. Plants selected based on their ethnopharmacological uses were extracted by either maceration or decoction using distilled water, ethanol, methanol and ethylacetate. The afforded extracts were phytochemically screened for bioactive secondary metabolites. The microdilution method was used to assess the antibacterial activity. The two promising extracts were tested in combination using the cbeckboard technique. Eighty one extracts showed antibacterial activity with eight having minimum inhibitory concentrations below 2.5 mg/mL. Results from combination assays with extracts from Terminalia catappa and Gnidia glauca leaves showed synergistic effect against Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi and additive effect against Staphylococcus aureus. These extracts mainly contained saponins, tannins, glucosides, phenols, triterpenes and anthraquinones. These results support the ethnobotanical claims and indicate further directions for the investigation of plants extracts to develop alternative drugs against multi-resistant bacteria.展开更多
The antibacterial effect of the crude methanol extracts and purified fractions of Ctadophora glomerata (Linnaeus) Kutzing (Cladophoraceae) against multidrug resistant human pathogen were investigated. The test bac...The antibacterial effect of the crude methanol extracts and purified fractions of Ctadophora glomerata (Linnaeus) Kutzing (Cladophoraceae) against multidrug resistant human pathogen were investigated. The test bacterial strains were Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus faecalis, Escherichia coli and S. typhimurium. Ethanol extract (0.5 mg/mL) of Cladophora glomerata inhibited growth of all the test organisms. Primary detection of active compounds showed that maeroalgae (Cladophora glomerata) containing flavonoids, alkaloids, phenols and tannins. Gas Chromatography-Mass Spectrometry was used to know the compounds which responsible of antibacterial activity and they were g-Pentadecanone that was found to be a major compound (42.67%) followed by 8-Octadecanone (22.43%) and Salicylic acid (20.04%) in addition to 10-hexadecaden (8.01%). These findings suggest the possibility of using the Cladophora glomerata as a novel source of natural antimicrobial agents in pharmaceutical industries.展开更多
The search for new prototype drugs to combat infection is an absolute necessity and in this regard plant essential oils may offer great potential and hope. In this investigation, the essential oil of the leaves ofMent...The search for new prototype drugs to combat infection is an absolute necessity and in this regard plant essential oils may offer great potential and hope. In this investigation, the essential oil of the leaves ofMentha officinalis grown in Rwanda was extracted by hydrodistillation method and analyzed by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS). The disc diffusion method was used to evaluate in vitro the zone of bacterial growth inhibition at various concentrations of the oil for five bacterial strains: Escherichia coli, Bacillus aureus, Streptococcus lactis, Staphylococcus aureus and Salmonella typhimurium. The results of this study revealed many components among which the major components were menthol (80.79%), menthone (4.906%), isomenthone (3.5%), piperitone (2.56%), and methyl acetate (2.2%). After 7 days of incubation on PCA medium, the growth of Escherichia coli, Bacillus aureus, Streptococcus lactis and Staphylococcus aureus was totally inhibited at an average diameter of 19 mm, 32 mm, 50 mm and 30 mm respectively by a medium concentration of 30 μm/disc ofM. officinalis oil. Quite the reverse, this investigation by a bioassay showed that the essential oil ofM. officinalis has no effect on Salmonella typhimurium. The obtained results in the present study indicate the possibility of exploiting the essential oil ofM. officinalis to combat so many infectious human diseases in Rwanda. However, further investigations are required to make the medical exploitation of this plant successful.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars of China (Grant No. 40725012)the National Hi-tech Research and Development Program of China(863 Program) (Grant No. 2006AA06Z240)the National Basic Research Program of China (973 program)(Grant No. 2007CB209505).
文摘To simultaneously take into account the Biot-flow mechanism, the squirt-flow mechanism, and the frame-viscoelasticity mechanism, a generalized viscoelastic BISQ (Biot/squirt) model is developed for wave propagation in clay-bearing sandstones based on Dvorkin's elastic BISQ model. The present model is extended to a wide range of permeabilities (k 〉 0.05 mD) by introducing a dimensionless correction factor for viscoelastic parameters, defined as a function of the permeability and the clay content. We describe the frame's stress-strain relationship of the clay-bearing sandstones by the differential constitutive equations of generalized viscoelasticity and then derive the viscoelastic-wave dynamic equations. With the assumption of a plane-wave solution, we finally yield the phase velocities and the attenuation coefficients by solving the dynamic wave equations in the frequency and wave number domain. The comparison of numerical results and experimental data shows that the generalized viscoelastic BISQ model is applicable for modeling the wave propagation in most of the sandstones mainly bearing kaolinite clay.
基金National Natural Science Foundation of Guangdong Province (020885,980504).
文摘Aim Ciprofloxacin polylactic acid microspheres (CFX-PLA-MS) were preparedusing solvent evaporation method from a solid-in-oil-in-water emulsion system. Methods Orthogonalexperiment was used to optimize the method of CFX-PLA-MS preparation. Microspheres werecharacterized in terms of morphology, size, encapsulation efficiency, drug loading and in vitro drugrelease. Results The physical state of CFX-PLA-MS was determined by scanning electron microscopy(SEM) and differential scanning calorimetry (DSC) . Microspheres formed were spherical with smoothsurfaces. Drug was enveloped in microspheres without mixing physically with PLA. The averageparticle size was 280.80 ± 0.15 μm, with over 90% of microspheres falling in the range of 250 -390 μm. The encapsulation efficiency was 65.8% ± 0.58% and the drug loading was 34.1% ± 0.51% .In vitro release study revealed a profile of sustained release of Ciprofloxacin from CFX-PLA-MS. Theaccumulated release percentage and half-life (T_(1/2) of Ciprofloxacin microspheres were 84.0% in53.2 h, and 31.9 h, respectively. Higuchi equation was Q= -0.0043 + 0.003 9 t^(1/2), r = 0.9941.Conclusion Ciprofloxacin microspheres have been successfully prepared and sustained release of CFXfrom microspheres is achieved.
基金Project (No. 30500229) supported partly by the National Natural Science Foundation of China
文摘Chylothorax is an uncommon disease where fatty fluid accumulates within the chest cavity. Conservative manage- ment, including repeated thoracentesis or pleurodesis, seems to be suitable to most cases. Herein, we present a case of efficacious pleurodesis by intrapleural injection of Sapylin, a streptococcus preparation, for the treatment of chylothorax. A 52-year-old non-smoking female farmer was diagnosed as idiopathic chylothorax after we ruled out possible causes including chest trauma, lymphoma, lung cancer, filariasis, tuberculosis, and etc. Two-time intra-thoracic injection of 3 Klinische Einheit (KE) Sapylin achieved rapid and effective control of chylothorax with no severe side effects. Sapylin may facilitate pleurodesis by producing a strong inflammatory response.
基金supported by the National Natural Science Foundation of China(NSFC)[grant number 41730536]
文摘The limitation of iron(Fe)makes the North Pacific a typically high-nitrate,low-chlorophyll(HNLC)region in comparison with other oceanic regions of the world.Iron inputs from land via river discharge and atmospheric dust deposition are the primary processes introducing Fe into the ocean.Also,subsequent physical processes are crucial in transporting biologically available Fe into the upper ocean.As anthropogenic dust increases,the Fe from anthropogenic activities is expected to become more important in terms of impacting marine ecosystems.To investigate the Fe cycle and its impact on ecosystems,a project entitled‘The sources and transport of Fe in the North Pacific and its impact on marine ecosystems’has been funded by the National Natural Science Foundation of China.The project will focus on three major scientific questions:(1)What are the major sources of Fe in the North Pacific?(2)What is the influence of the Fe-binding ligand cycle on marine ecosystems?(3)What is the likely influence of global change in the future?The distribution of Fe and its corresponding impact on the marine ecosystem in current and future environmental conditions will be investigated.The results of the project are expected to improve our understanding of the marine ecosystem in the North Pacific.
基金This study was supported by the National 863 Project of China (2012AA021801) and the Project of Frontier Study of Foundation, CAS (KSCX2-EW-R-11, KSCX2-EW-J-23)
文摘Endosymbionts influence many aspects of their hosts’ health conditions, including physiology, development, immunity, metabolism, etc. Tree shrews(Tupaia belangeri chinensis) have attracted increasing attention in modeling human diseases and therapeutic responses due to their close relationship with primates. To clarify the situation of symbiotic bacteria from their body surface, oral cavity, and anus, 12 wild and 12 the third generation of captive tree shrews were examined. Based on morphological and cultural characteristics, physiological and biochemical tests, as well as the 16 S rDNA full sequence analysis, 12 bacteria strains were isolated and identified from the wild tree shrews: body surface: Bacillus subtilis(detection rate 42%), Pseudomonas aeruginosa(25%), Staphlococcus aureus(33%), S. Epidermidis(75%), Micrococcus luteus(25%), Kurthia gibsonii(17%); oral cavity: Neisseria mucosa(58%), Streptococcus pneumonia(17%); anus: Enterococcus faecalis(17%), Lactococus lactis(33%), Escherichia coli(92%), Salmonella typhosa(17%); whereas, four were indentified from the third generation captive tree shrews: body surface: S. epidermidis(75%); oral cavity: N.mucosa(67%); anus: L. lactis(33%), E. coli(100%). These results indicate that S. epidermidis, N. mucosa, L. lactis and E. coli were major bacteria in tree shrews, whereas, S. aureus, M. luteus, K. gibsonii, E. faecalis and S. typhosa were species-specific flora. This study facilitates the future use of tree shrews as a standard experimental animal and improves our understanding of the relationship between endosymbionts and their hosts.
文摘Geotechnical properties of sedimentary rocks exposed along upper Egypt-Red Sea road were investigated to evaluate their geotechnical behavior. One of the most important aims of this work was to determine the engineering problems affected on the road due to the geotechnical behavior of the studied sedimentary rocks and to suggest the suitable solution. Specific weight, unconfined compressive strength, slaking durability and free swelling were measured. The results showed that the studied crystalline limestone, marly limestone and Issawia limestone had higher unconfined compressive strength values ranging from 34,184.00 kN/m2 to 42,602.00 kN/m2 and the studied shale, siltstone and coral reef had lower values ranging from 3,689.00 kN/m2 to 6,933.00 kN/m2. The results showed also that the studied shale, siltstone and mudstone had fast to very fast slaking rate and their slaking amount described as low to medium after Gamble's slake durability classification. Replacement and/or chemical stabilization (using lime and/or cement kiln dust) of the expansive sedimentary rocks (shale and mudstone) were recommended to reduce the swelling. Geophysical investigations including shallow seismic, microgravity and GPR (ground penetrating radar) were recommended to scan the sub-grade of the road at El Maaza plateau to determine possible other caves and large voids under the road to avoid its collapse.
基金supported by the ORS Award to Giri Kattel, ENSIS Ltd Trust Fund,Department of Geography and UCL Graduate School Research Scholarships
文摘Representativity of biota in the biosphere also have similar significance in the lithosphere after their death. Recently, taphonomic representation of biota in the lithosphere has been widely used for minimizing the biases in palaeo-environmental reconstructions including global climate change. In September 2001, a sediment trap was installed at the central area of the Loch Coire Fionnaraich (LCFR), a small, oligotrophic mountain loch in northwest Scotland for a taphonomic study of cladoceran zooplankton. The trap was emptied on a seasonal basis, where an average 0.14 g dry material was recovered in each season, January, May and August 2002 respectively. A sediment core was also taken from near the sediment trap location. The top 0.5 cm section, the 'core' was used for a comparative study with the trap sediment samples. The planktonic Cladocera consisted of Bosmina coregoni and appeared to have excellent preservation in the trap assemblages. Moreover, some common littoral Cladocera such as Alonella excisa and Aloha guttata appear to be less well preserved in the fossil assemblages. Large littoral taxa such as Eurycercus lamellatus and Aloha quadrangularis were rare in the trap but relatively common and well preserved in the sediment-water interface. It is suggested that taphonomic processes play a dominant role on deposition of fossil remains of Cladocera and caution should be taken while inferring the past environmental changes whilst using fossil assemblages recovered from the lake centre as a representation of the entire cladoceran community in the lake.
文摘Mine rocky desertification is another type of rocky desertification which coexists with Karst rocky desertification, suggested firstly by professor SONG Jian-bo, Guizhou University. Mine rocky desertification is a process and result that the earth's surface is similar to desert landscapes after rock is exposed gradually, owing to mine wastes discharged at will which consist of waste residue, waste liquid and waste gas. On the basis of introducing Karst rocky desertification simply, we clarify the concept of Mine rocky desertification systemically, analyze its danger and compare the differences between Mine rocky desertification and Karst rocky desertification. Finally, we make preliminary discussion on the study significance of comprehensive treatment of Mine rocky desertification
文摘Multi-drug resistant microbial infections caused by Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi represent a critical public health issue worldwide. Plant-derived agents are credible sources for search and development of alternative antimicrobials to fight these infections. This study describes the in-vitro antibacterial activity of plants extracts from 15 medicinal plants of the Cameroonian pharmacopeia against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi. Plants selected based on their ethnopharmacological uses were extracted by either maceration or decoction using distilled water, ethanol, methanol and ethylacetate. The afforded extracts were phytochemically screened for bioactive secondary metabolites. The microdilution method was used to assess the antibacterial activity. The two promising extracts were tested in combination using the cbeckboard technique. Eighty one extracts showed antibacterial activity with eight having minimum inhibitory concentrations below 2.5 mg/mL. Results from combination assays with extracts from Terminalia catappa and Gnidia glauca leaves showed synergistic effect against Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi and additive effect against Staphylococcus aureus. These extracts mainly contained saponins, tannins, glucosides, phenols, triterpenes and anthraquinones. These results support the ethnobotanical claims and indicate further directions for the investigation of plants extracts to develop alternative drugs against multi-resistant bacteria.
文摘The antibacterial effect of the crude methanol extracts and purified fractions of Ctadophora glomerata (Linnaeus) Kutzing (Cladophoraceae) against multidrug resistant human pathogen were investigated. The test bacterial strains were Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus faecalis, Escherichia coli and S. typhimurium. Ethanol extract (0.5 mg/mL) of Cladophora glomerata inhibited growth of all the test organisms. Primary detection of active compounds showed that maeroalgae (Cladophora glomerata) containing flavonoids, alkaloids, phenols and tannins. Gas Chromatography-Mass Spectrometry was used to know the compounds which responsible of antibacterial activity and they were g-Pentadecanone that was found to be a major compound (42.67%) followed by 8-Octadecanone (22.43%) and Salicylic acid (20.04%) in addition to 10-hexadecaden (8.01%). These findings suggest the possibility of using the Cladophora glomerata as a novel source of natural antimicrobial agents in pharmaceutical industries.
文摘The search for new prototype drugs to combat infection is an absolute necessity and in this regard plant essential oils may offer great potential and hope. In this investigation, the essential oil of the leaves ofMentha officinalis grown in Rwanda was extracted by hydrodistillation method and analyzed by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS). The disc diffusion method was used to evaluate in vitro the zone of bacterial growth inhibition at various concentrations of the oil for five bacterial strains: Escherichia coli, Bacillus aureus, Streptococcus lactis, Staphylococcus aureus and Salmonella typhimurium. The results of this study revealed many components among which the major components were menthol (80.79%), menthone (4.906%), isomenthone (3.5%), piperitone (2.56%), and methyl acetate (2.2%). After 7 days of incubation on PCA medium, the growth of Escherichia coli, Bacillus aureus, Streptococcus lactis and Staphylococcus aureus was totally inhibited at an average diameter of 19 mm, 32 mm, 50 mm and 30 mm respectively by a medium concentration of 30 μm/disc ofM. officinalis oil. Quite the reverse, this investigation by a bioassay showed that the essential oil ofM. officinalis has no effect on Salmonella typhimurium. The obtained results in the present study indicate the possibility of exploiting the essential oil ofM. officinalis to combat so many infectious human diseases in Rwanda. However, further investigations are required to make the medical exploitation of this plant successful.