Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Braz. j. biol ; 82: e232434, 2022. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1153465

RESUMO

Abstract Many pathogenic strains have acquired multidrug-resistant patterns in recent a year, which poses a major public health concern. The growing need for effective antimicrobial agents as novel therapies against multidrug-resistant pathogens has drawn scientist attention toward nanotechnology. Silver nanoparticles are considered capable of killing multidrug-resistant isolates due to their oligo-dynamic effect on microorganisms. In this research study NPs were synthesized using the gram-positive bacteria Lactobacillus bulgaricus and its activity against selected pathogenic strains. Lactobacillus bulgaricus pure cultures were isolated from raw milk and grown in "De Man, Rogasa, and Sharp" broth for synthesis of nanoparticles. Lactobacillus bulgaricus culture was centrifuged and Cell- free supernatant of it was employed with aqueous silvery ions and evaluated their antibacterial activities against bacterial strains i.e. Staphylococcus aureus, Staphylococcus epidermidis and Salmonella typhi using agar well diffusion assay. Antibiotic profiling against selected pathogenic strains were also conducted using disc diffusion method. The synthesis and characterization of silver nanoparticles were monitored primarily by the conversion of the pale-yellow color of the mixture into a dark-brown color and via ultraviolet-visible absorption spectroscopy and Scanning electron microscopy respectively. The result showed that that AgNPs with size (30.65-100 nm) obtained from Lactobacillus bulgaricus were found to exhibit antibacterial activities against selected bacterial strains. Taken together, these findings suggest that Lactobacillus bulgaricus has great potential for the production of AgNPs with antibacterial activities and highly effective in comparison to tested antibiotics.


Resumo Muitas cepas patogênicas adquiriram padrões multirresistentes nos últimos anos, o que representa um grande problema de saúde pública. A crescente necessidade de agentes antimicrobianos eficazes como novas terapias contra patógenos multirresistentes atraiu a atenção dos cientistas para a nanotecnologia. As nanopartículas de prata são consideradas capazes de matar isolados multirresistentes por causa de seu efeito oligodinâmico em microrganismos. Neste estudo de pesquisa, as NPs foram sintetizadas usando a bactéria Gram-positiva Lactobacillus bulgaricus e sua atividade contra cepas patogênicas selecionadas. Culturas puras de Lactobacillus bulgaricus foram isoladas do leite cru e cultivadas em caldo "De Man, Rogasa e Sharp" para síntese de nanopartículas. A cultura de Lactobacillus bulgaricus foi centrifugada, e o sobrenadante livre de células foi empregado com íons prateados aquosos, avaliando-se suas atividades antibacterianas contra cepas bacterianas, isto é, Staphylococcus aureus, Staphylococcus epidermidis e Salmonella typhi usando ensaio de difusão em poço de ágar. O perfil de antibióticos contra cepas patogênicas selecionadas também foi conduzido usando o método de difusão em disco. A síntese e a caracterização das nanopartículas de prata foram monitoradas principalmente pela conversão da cor amarelo-pálida da mistura em uma cor marrom-escura e por espectroscopia de absorção visível e ultravioleta e por microscopia eletrônica de varredura, respectivamente. O resultado mostrou que AgNPs com tamanho de 30,65-100 nm, obtidas de Lactobacillus bulgaricus, exibiram atividades antibacterianas contra cepas bacterianas selecionadas. Tomados em conjunto, esses achados sugerem que o Lactobacillus bulgaricus tem um grande potencial para a produção de AgNPs com atividades antibacterianas e altamente eficazes em comparação aos antibióticos testados.

2.
PLoS One ; 16(5): e0250242, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33945537

RESUMO

Corporate governance is the way of governing a firm in order to increase its accountability and to avoid any massive damage before it occurs. The aim of this paper is to investigate the impact of capital structure, firms' size, and competitive advantages of firms as control variables on credit ratings. We investigate the role of corporate governance in improving the firms' credit rating using a sample of Jordanian listed firms. We split firms into four categories according to WVB credit rating. We use both the binary logistic regression (LR) and the ordinal logistic regression (OLR) to model credit ratings in Jordanian environment. The empirical results show that the control variables are strong determinants of credit ratings. When we evaluate the relationship between the governance variables and credit ratings, we found interesting results. The board stockholders and board expertise are moderately significant. The board independence and role duality are weakly significant, while board size is insignificant.

3.
Braz J Biol ; 82: e232434, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33681895

RESUMO

Many pathogenic strains have acquired multidrug-resistant patterns in recent a year, which poses a major public health concern. The growing need for effective antimicrobial agents as novel therapies against multidrug-resistant pathogens has drawn scientist attention toward nanotechnology. Silver nanoparticles are considered capable of killing multidrug-resistant isolates due to their oligo-dynamic effect on microorganisms. In this research study NPs were synthesized using the gram-positive bacteria Lactobacillus bulgaricus and its activity against selected pathogenic strains. Lactobacillus bulgaricus pure cultures were isolated from raw milk and grown in "De Man, Rogasa, and Sharp" broth for synthesis of nanoparticles. Lactobacillus bulgaricus culture was centrifuged and Cell- free supernatant of it was employed with aqueous silvery ions and evaluated their antibacterial activities against bacterial strains i.e. Staphylococcus aureus, Staphylococcus epidermidis and Salmonella typhi using agar well diffusion assay. Antibiotic profiling against selected pathogenic strains were also conducted using disc diffusion method. The synthesis and characterization of silver nanoparticles were monitored primarily by the conversion of the pale-yellow color of the mixture into a dark-brown color and via ultraviolet-visible absorption spectroscopy and Scanning electron microscopy respectively. The result showed that that AgNPs with size (30.65-100 nm) obtained from Lactobacillus bulgaricus were found to exhibit antibacterial activities against selected bacterial strains. Taken together, these findings suggest that Lactobacillus bulgaricus has great potential for the production of AgNPs with antibacterial activities and highly effective in comparison to tested antibiotics.


Assuntos
Anti-Infecciosos , Lactobacillus delbrueckii , Nanopartículas Metálicas , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana , Prata/farmacologia
4.
Nat Commun ; 5: 4040, 2014 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-24925481

RESUMO

The discovery of a natural quasicrystal, icosahedrite (Al63Cu24Fe13), accompanied by khatyrkite (CuAl2) and cupalite (CuAl) in the CV3 carbonaceous chondrite Khatyrka has posed a mystery as to what extraterrestrial processes led to the formation and preservation of these metal alloys. Here we present a range of evidence, including the discovery of high-pressure phases never observed before in a CV3 chondrite, indicating that an impact shock generated a heterogeneous distribution of pressures and temperatures in which some portions reached at least 5 GPa and 1,200 °C. The conditions were sufficient to melt Al-Cu-bearing minerals, which then rapidly solidified into icosahedrite and other Al-Cu metal phases. The meteorite also contains heretofore unobserved phases of iron-nickel and iron sulphide with substantial amounts of Al and Cu. The presence of these phases in Khatyrka provides further proof that the Al-Cu alloys are natural products of unusual processes that occurred in the early solar system.

5.
J Int Med Res ; 40(1): 393-7, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22429381

RESUMO

OBJECTIVE: This observational, retrospective study investigated infertility among Iraqi men who had been long-term prisoners of war. METHODS: Routine seminal fluid analyses were undertaken in former prisoners with suspected infertility attending the Ramadi Infertility Clinic, Ramadi, Iraq; semen samples were also microscopically evaluated in these patients. RESULTS: In 16 out of 38 patients (42%), male infertility was found to be associated with the formation of unusually large clumps of sperm. These sperm clumps contained large numbers of sperm; clumping led to sperm immobilization and infertility. CONCLUSIONS: The causes of sperm clumping are unclear. It is possible that the sperm clumping observed in the present study might be a result of developmental defects, possibly related to stress or other undiscovered factors, although this requires further investigation.


Assuntos
Infertilidade Masculina/patologia , Prisioneiros , Espermatozoides/patologia , Adulto , Agregação Celular , Humanos , Iraque , Masculino , Sêmen
7.
J Gen Microbiol ; 128(2): 303-6, 1982 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-6804596

RESUMO

Electron microscopy of Neisseria gonorrhoeae grown on solid medium with a subinhibitory concentration of penicillin suggested that the amount of penicillin reaching each pair of gonococci was different, as illustrated by the ultrastructural appearance of N, gonorrhoeae cells in the colony. This supports the view that the concentration of penicillin in different parts of the colony is not uniform, causing some cells to lyse while the others remain intact.


Assuntos
Neisseria gonorrhoeae/efeitos dos fármacos , Penicilina G/farmacologia , Bacteriólise , Meios de Cultura , Testes de Sensibilidade Microbiana , Microscopia Eletrônica , Neisseria gonorrhoeae/ultraestrutura
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...