The Experts below are selected from a list of 807 Experts worldwide ranked by ideXlab platform
Yusaku Fujio - One of the best experts on this subject based on the ideXlab platform.
-
oscillatory compared with continuous high pressure sterilization on bacillus stearothermophilus spores
Journal of Food Science, 1994Co-Authors: Isao Hayakawa, T Kanno, K Yoshiyama, Yusaku FujioAbstract:TO ESTABLISH a sterilization method with minimal heating, the effect of high pressure on Bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus. After exposure to 800 MPa for 60 min at 60°C, the spore count decreased from 106 to 102/mL. However, exposure to the same pressure at room temperature did not cause significant change in spore numbers. The synergistic effect of high pressurization on the bacteriostatic action of sucrose fatty acid ester at low concentration (< 10 ppm) was pronounced with sucrose palmitic acid ester but not with sucrose stearic acid ester. Oscillatory pressurization was more effective for spore sterilization. Six cycles oscillation of 5-min pressurization with 400 MPa at 70°C decreased the spore count from 106 to 102/mL, and with 600 MPa, complete sterilization was achieved.
-
oscillatory compared with continuous high pressure sterilization on bacillus stearothermophilus spores
Journal of Food Science, 1994Co-Authors: Isao Hayakawa, T Kanno, K Yoshiyama, Yusaku FujioAbstract:TO ESTABLISH a sterilization method with minimal heating, the effect of high pressure on Bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus. After exposure to 800 MPa for 60 min at 60°C, the spore count decreased from 106 to 102/mL. However, exposure to the same pressure at room temperature did not cause significant change in spore numbers. The synergistic effect of high pressurization on the bacteriostatic action of sucrose fatty acid ester at low concentration (< 10 ppm) was pronounced with sucrose palmitic acid ester but not with sucrose stearic acid ester. Oscillatory pressurization was more effective for spore sterilization. Six cycles oscillation of 5-min pressurization with 400 MPa at 70°C decreased the spore count from 106 to 102/mL, and with 600 MPa, complete sterilization was achieved.
David R. Sherman - One of the best experts on this subject based on the ideXlab platform.
-
Mycobacterium tuberculosis Ser/Thr protein kinase B mediates an oxygen-dependent replication switch.
Public Library of Science (PLoS), 2014Co-Authors: Corrie Ortega, Reiling Liao, David R. Sherman, Lindsey N Anderson, Tige Rustad, Anja R Ollodart, Aaron T Wright, Christoph GrundnerAbstract:The majority of Mycobacterium tuberculosis (Mtb) infections are clinically latent, characterized by drug tolerance and little or no bacterial replication. Low oxygen tension is a major host factor inducing Bacteriostasis, but the molecular mechanisms driving oxygen-dependent replication are poorly understood. Here, we tested the role of serine/threonine phosphorylation in the Mtb response to altered oxygen status, using an in vitro model of latency (hypoxia) and reactivation (reaeration). Broad kinase inhibition compromised survival of Mtb in reaeration. Activity-based protein profiling and genetic mutation identified PknB as the kinase critical for surviving hypoxia. Mtb replication was highly sensitive to changes in PknB levels in aerated culture, and even more so in hypoxia. A mutant overexpressing PknB specifically in hypoxia showed a 10-fold loss in viability and gross morphological defects in low oxygen conditions. In contrast, chemically reducing PknB activity during hypoxia specifically compromised resumption of growth during reaeration. These data support a model in which PknB activity is reduced to achieve Bacteriostasis, and elevated when replication resumes. Together, these data show that phosphosignaling controls replicative transitions associated with latency and reactivation, that PknB is a major regulator of these transitions, and that PknB could provide a highly vulnerable therapeutic target at every step of the Mtb life cycle-active disease, latency, and reactivation
-
The Enduring Hypoxic Response of Mycobacterium tuberculosis
2013Co-Authors: Tige R. Rustad, Maria I. Harrell, Reiling Liao, David R. ShermanAbstract:Background. A significant body of evidence accumulated over the last century suggests a link between hypoxic microenvironments within the infected host and the latent phase of tuberculosis. Studies to test this correlation have identified the M. tuberculosis initial hypoxic response, controlled by the two-component response regulator DosR. The initial hypoxic response is completely blocked in a dosR deletion mutant. Methodology/Principal Findings. We show here that a dosR deletion mutant enters Bacteriostasis in response to in vitro hypoxia with only a relatively mild decrease in viability. In the murine infection model, the phenotype of the mutant was indistinguishable from that of the parent strain. These results suggested that additional genes may be essential for entry into and maintenance of Bacteriostasis. Detailed microarray analysis of oxygen starved cultures revealed that DosR regulon induction is transient, with induction of nearly half the genes returning to baseline within 24 hours. In addition, a larger, sustained wave of gene expression follows the DosR-mediated initial hypoxic response. This Enduring Hypoxic Response (EHR) consists of 230 genes significantly induced at four and seven days of hypoxia but not at initial time points. These genes include a surprising number of transcriptional regulators that could control the program of Bacteriostasis. We found that the EHR is independent of the DosR-mediated initial hypoxic response, as EHR expression is virtually unaltered in the dosR mutant. Conclusions/Significance. Our results suggest a reassessment of the role of DosR and the initial hypoxic response in MTB physiology. Instead of a primary role in survival of hypoxia induced Bacteriostasis, DosR may regulate a response that is largely optional in vitro and in mouse infections. Analysis of the EH
-
Mycobacterium tuberculosis Ser/Thr Protein Kinase B Mediates an Oxygen-Dependent Replication Switch
2013Co-Authors: Corrie Ortega, Reiling Liao, David R. Sherman, Lindsey N Anderson, Tige Rustad, Anja R Ollodart, Aaron T Wright, Christoph GrundnerAbstract:The majority of Mycobacterium tuberculosis (Mtb) infections are clinically latent, characterized by drug tolerance and little or no bacterial replication. Low oxygen tension is a major host factor inducing Bacteriostasis, but the molecular mechanisms driving oxygen-dependent replication are poorly understood. Here, we tested the role of serine/threonine phosphorylation in the Mtb response to altered oxygen status, using an in vitro model of latency (hypoxia) and reactivation (reaeration). Broad kinase inhibition compromised survival of Mtb in reaeration. Activity-based protein profiling and genetic mutation identified PknB as the kinase critical for surviving hypoxia. Mtb replication was highly sensitive to changes in PknB levels in aerated culture, and even more so in hypoxia. A mutant overexpressing PknB specifically in hypoxia showed a 10-fold loss in viability and gross morphological defects in low oxygen conditions. In contrast, chemically reducing PknB activity during hypoxia specifically compromised resumption of growth during reaeration. These data support a model in which PknB activity is reduced to achieve Bacteriostasis, and elevated when replication resumes. Together, these data show that phosphosignaling controls replicative transitions associated with latency and reactivation, that PknB is a major regulator of these transitions, and that PknB could provide a highly vulnerable therapeutic target at every step of the Mtb life cycle
-
Mycobacterium tuberculosis Growth following Aerobic Expression of the DosR Regulon
PLOS ONE, 2012Co-Authors: Kyle J. Minch, Tige R. Rustad, David R. ShermanAbstract:The Mycobacterium tuberculosis regulator DosR is induced by multiple stimuli including hypoxia, nitric oxide and redox stress. Overlap of these stimuli with conditions thought to promote latency in infected patients fuels a model in which DosR regulon expression is correlated with Bacteriostasis in vitro and a proxy for latency in vivo. Here, we find that inducing the DosR regulon to wildtype levels in aerobic, replicating M. tuberculosis does not alter bacterial growth kinetics. We conclude that DosR regulon expression alone is insufficient for bacterial latency, but rather is expressed during a range of growth states in a dynamic environment.
J.m Wiest - One of the best experts on this subject based on the ideXlab platform.
-
Atividade antibacteriana in vitro de inflorescências de Achyrocline satureioides (Lam.) DC. - Asteraceae ("macela", "marcela") sobre agentes bacterianos de interesse em alimentos In vitro antibacterial activity of inflorescences of Achyroclines satureioides (Lam.) DC. - Asteraceae ("macela", "marcela") on bacterial agents of interest in food
Universidade Estadual Paulista, 2011Co-Authors: F.m Mota, H.h.c Carvalho, J.m WiestAbstract:Através de Testes de diluição em sistema de tubos múltiplos determinou-se in vitro, atividade antibacteriana em inflorescências de Achyrocline satureioides (Lam.) DC. - Asteraceae ("macela", "marcela"), expressa como Intensidade de Atividade de Inibição Bacteriana (IINIB/bacteriostasia) e Intensidade de Atividade de Inativação Bacteriana (IINAB/bactericidia), a partir de formas de extração etanólica (hidroalcoolaturas) e hídrica (decoctos), sobre inóculos padronizados de Enterococcus faecalis (ATCC 19433), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 11229) e Salmonella enteritidis (ATCC 11076). E. faecalis apresentou a maior sensibilidade, seguido por Staphylococcus aureus, enquanto S. enteritidis e E. coli apresentaram-se mais resistentes. Dentre as formas de extração, a hidroalcoolatura apresentou capacidade de inibição e/ou inativação intensa e seletiva frente aos quatro inóculos bacterianos. Os decoctos mostraram-se completamente ineficazes frente às bactérias Gram-negativas, enquanto que as Gram-positivas apresentaram somente bacteriostasia/inibição.Dilution test in multiple tube system was used to determine the in vitro antibacterial activity in inflorescences of Achyrocline satureioides (Lam.) DC. - Asteraceae ("macela", "marcela"), expressed as intensity of bacterial inhibition activity (IINIB/Bacteriostasis) and intensity of bacterial inactivation activity (IINAB/bactericidie), from ethanol (hydroalcoholic) and water (decoction) extraction forms on standardized inocula of Enterococcus faecalis (ATCC 19433), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 11229) and Salmonella enteritidis (ATCC 11076). E. faecalis had the highest sensitivity, followed by S. aureus, while S. enteritidis and E. coli were more resistant. Of the extraction forms, the hydroalcoholic one showed intense and selective inhibition and/or inactivation capacity against four bacterial inocula. Decoctions were completely ineffective against the Gram-negative bacteria, whereas Gram-positive bacteria showed only Bacteriostasis/inhibition
-
Inibição e inativação in vitro de diferentes métodos de extração de Ocimum gratissimum L. ("alfavacão", "alfavaca", "alfavaca-cravo") - Labiatae (Lamiaceae), frente a bactérias de interesse em alimentos In vitro inhibition and inactivation of different extraction methods in Ocimum gratissimum L. ("alfavacão", "alfavaca", "alfavaca-cravo") - Labiatae (Lamiaceae) against foodborne bacteria of interest
Universidade Estadual Paulista, 2009Co-Authors: M.g. Passos, H. Carvalho, J.m WiestAbstract:Através de testes de diluição em sistema de tubos múltiplos determinou-se a intensidade de atividade de inibição bacteriana (IINIB/bacteriostasia) e a intensidade de atividade de inativação bacteriana (IINAB/bactericidia) de soluções conservantes contendo extratos etanólicas (alcoolatura/planta in natura, hidroalcoolatura/planta seca) e hídricas (decoctos /planta in natura ou seca) de Ocimum gratissimum L. ("alfavacão", "alfavaca", "alfavaca-cravo") - Labiatae (Lamiaceae), sobre inóculos padronizados de Salmonella enteritidis (ATCC 11076), Escherichia coli (ATCC 11229) e Staphylococcus aureus (ATCC 25923). Todas as diferentes formas de extração apresentaram capacidade de inibição e/ou inativação seletivas sobre os inóculos bacterianos, tendo o extrato alccólico apresentado a atividade antibacteriana mais intensa (inibição/inativação) frente aos três agentes. A bactéria mais sensível à atividade antibacteriana em todas as soluções conservantes foi Salmonella enteritidis. Staphylococcus aureus apresentou a menor sensibilidade às formas de decocção, enquanto Escherichia coli apresentou a menor sensibilidade frente ao extrato hidroalcoólico.Dilution tests in multiple tube system were used to evaluate the intensity of bacterial inhibition activity (IINIB/Bacteriostasis) and bacterial inactivation activity (IINAB/bactericide) of conserver solutions containing ethanolic (alcoholature/in natura plant, hidroalcoholature/dry plant) and aqueous (decoctions/in natura or dry plant) extracts of Ocimum gratissimum L. ("alfavacão", "alfavaca", "alfavaca-cravo") - Labiatae - (Lamiaceae) on standardized inocula of Salmonella enteritidis (ATCC 11076), Escherichia coli (ATCC 11229) and Staphylococcus aureus (ATCC 25923). All the different extraction methods presented selective inhibition and/or inactivation on the bacterial inocula. The alcoholic extract had the highest antibacterial activity (inhibition/inactivation) against the three agents. Salmonella enteritidis was the most sensitive to the antibacterial activity in all conserver solutions. Staphylococcus aureus showed the lowest sensitivity to decoctions, whereas Escherichia coli was the least sensitive to the hydroalcoholic extraction
Isao Hayakawa - One of the best experts on this subject based on the ideXlab platform.
-
oscillatory compared with continuous high pressure sterilization on bacillus stearothermophilus spores
Journal of Food Science, 1994Co-Authors: Isao Hayakawa, T Kanno, K Yoshiyama, Yusaku FujioAbstract:TO ESTABLISH a sterilization method with minimal heating, the effect of high pressure on Bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus. After exposure to 800 MPa for 60 min at 60°C, the spore count decreased from 106 to 102/mL. However, exposure to the same pressure at room temperature did not cause significant change in spore numbers. The synergistic effect of high pressurization on the bacteriostatic action of sucrose fatty acid ester at low concentration (< 10 ppm) was pronounced with sucrose palmitic acid ester but not with sucrose stearic acid ester. Oscillatory pressurization was more effective for spore sterilization. Six cycles oscillation of 5-min pressurization with 400 MPa at 70°C decreased the spore count from 106 to 102/mL, and with 600 MPa, complete sterilization was achieved.
-
oscillatory compared with continuous high pressure sterilization on bacillus stearothermophilus spores
Journal of Food Science, 1994Co-Authors: Isao Hayakawa, T Kanno, K Yoshiyama, Yusaku FujioAbstract:TO ESTABLISH a sterilization method with minimal heating, the effect of high pressure on Bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus. After exposure to 800 MPa for 60 min at 60°C, the spore count decreased from 106 to 102/mL. However, exposure to the same pressure at room temperature did not cause significant change in spore numbers. The synergistic effect of high pressurization on the bacteriostatic action of sucrose fatty acid ester at low concentration (< 10 ppm) was pronounced with sucrose palmitic acid ester but not with sucrose stearic acid ester. Oscillatory pressurization was more effective for spore sterilization. Six cycles oscillation of 5-min pressurization with 400 MPa at 70°C decreased the spore count from 106 to 102/mL, and with 600 MPa, complete sterilization was achieved.
K Yoshiyama - One of the best experts on this subject based on the ideXlab platform.
-
oscillatory compared with continuous high pressure sterilization on bacillus stearothermophilus spores
Journal of Food Science, 1994Co-Authors: Isao Hayakawa, T Kanno, K Yoshiyama, Yusaku FujioAbstract:TO ESTABLISH a sterilization method with minimal heating, the effect of high pressure on Bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus. After exposure to 800 MPa for 60 min at 60°C, the spore count decreased from 106 to 102/mL. However, exposure to the same pressure at room temperature did not cause significant change in spore numbers. The synergistic effect of high pressurization on the bacteriostatic action of sucrose fatty acid ester at low concentration (< 10 ppm) was pronounced with sucrose palmitic acid ester but not with sucrose stearic acid ester. Oscillatory pressurization was more effective for spore sterilization. Six cycles oscillation of 5-min pressurization with 400 MPa at 70°C decreased the spore count from 106 to 102/mL, and with 600 MPa, complete sterilization was achieved.
-
oscillatory compared with continuous high pressure sterilization on bacillus stearothermophilus spores
Journal of Food Science, 1994Co-Authors: Isao Hayakawa, T Kanno, K Yoshiyama, Yusaku FujioAbstract:TO ESTABLISH a sterilization method with minimal heating, the effect of high pressure on Bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus. After exposure to 800 MPa for 60 min at 60°C, the spore count decreased from 106 to 102/mL. However, exposure to the same pressure at room temperature did not cause significant change in spore numbers. The synergistic effect of high pressurization on the bacteriostatic action of sucrose fatty acid ester at low concentration (< 10 ppm) was pronounced with sucrose palmitic acid ester but not with sucrose stearic acid ester. Oscillatory pressurization was more effective for spore sterilization. Six cycles oscillation of 5-min pressurization with 400 MPa at 70°C decreased the spore count from 106 to 102/mL, and with 600 MPa, complete sterilization was achieved.
