RESUMO
BACKGROUND: Maintaining an adequate temperature at the target site is essential for effective ablation. We hypothesized that a tissue temperature-controlled (T-Con) catheter for cavotricuspid isthmus (CTI) ablation could improve the procedural ablation parameters. PURPOSE: To evaluate the efficacy and safety of the T-Con (DiamondTemp™) catheter for CTI ablation compared with non-irrigation (Non-Irri) and irrigation (Irri) catheters. METHODS: We analyzed 150 patients who underwent prophylactic CTI ablation combined with pulmonary vein isolation. The Non-Irri, Irri, and T-Con catheter groups comprised 50 patients each, and the ablation procedural parameters and complications were compared between these groups. RESULTS: There were no significant differences in clinical background characteristics among the three groups. The Kruskal-Wallis and post hoc tests demonstrated that the T-Con group showed the lowest total radiofrequency energy delivery time among the three groups (median [25 and 75 percentiles]: 340 [209, 357], 147 [100, 199], and 83 [61, 109] s, respectively in the Non-Irri, Irri, and T-Con groups; T-Con versus Non-Irri, p < .01; T-Con versus Irri, p < .01). The total procedural time and acute reconnection rate in the T-Con group (264 s and 4%, respectively) were lower than those in the Non-Irri group (438 s and 24%) but were similar to those in the Irri group (268 s and 6%). No significant complications were observed in any group. CONCLUSIONS: The T-Con catheter achieved a short energy delivery time and a low acute reconnection rate, indicating its potential as an alternative catheter for CTI ablation.
RESUMO
Rapidly progressive in-stent restenosis (ISR) after stent deployment from the left main trunk (LMT) to the left anterior descending artery (LAD) without plaque at the LMT ostium has not been reported. A 60-year-old Japanese man with a history of scleroderma, pulmonary fibrosis, and type 2 diabetes developed acute myocardial infarction of the right coronary artery (RCA) and was treated by emergency percutaneous coronary intervention (PCI) for RCA. Nine days later he underwent PCI from the LMT to the LAD. Follow-up coronary angiography (CAG) at 9 and 21 months post-PCI did not reveal ISR in any lesion, but the patient experienced cardiac arrest at 25 months post-PCI. Emergency CAG after resuscitation revealed ISR of the LMT ostium; emergency PCI was conducted. The development of ISR at the ostium of the LMT although the patient was free of plaque 4 months before is extremely unusual. This rare ISR of the LMT ostium progressed rapidly after follow-up CAG revealed no ISR at 21 months post-stent implantation.
Assuntos
Doença da Artéria Coronariana/cirurgia , Estenose Coronária/cirurgia , Constrição Patológica/cirurgia , Angiografia Coronária , Reestenose Coronária/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Intervenção Coronária Percutânea , Fatores de Risco , Stents , Resultado do TratamentoRESUMO
BACKGROUND: Remote monitoring (RM) has been advocated as the new standard of care for patients with cardiovascular implantable electronic devices (CIEDs). RM has allowed the early detection of adverse clinical events, such as arrhythmia, lead failure, and battery depletion. However, lead failure was often identified only by arrhythmic events, but not impedance abnormalities. OBJECTIVE: To compare the usefulness of arrhythmic events with conventional impedance abnormalities for identifying lead failure in CIED patients followed by RM. METHODS: CIED patients in 12 hospitals have been followed by the RM center in Okayama University Hospital. All transmitted data have been analyzed and summarized. RESULTS: From April 2009 to March 2016, 1,873 patients have been followed by the RM center. During the mean follow-up period of 775 days, 42 lead failure events (atrial lead 22, right ventricular pacemaker lead 5, implantable cardioverter defibrillator [ICD] lead 15) were detected. The proportion of lead failures detected only by arrhythmic events, which were not detected by conventional impedance abnormalities, was significantly higher than that detected by impedance abnormalities (arrhythmic event 76.2%, 95% CI: 60.5-87.9%; impedance abnormalities 23.8%, 95% CI: 12.1-39.5%). Twenty-seven events (64.7%) were detected without any alert. Of 15 patients with ICD lead failure, none has experienced inappropriate therapy. CONCLUSIONS: RM can detect lead failure earlier, before clinical adverse events. However, CIEDs often diagnose lead failure as just arrhythmic events without any warning. Thus, to detect lead failure earlier, careful human analysis of arrhythmic events is useful.
Assuntos
Arritmias Cardíacas/terapia , Estimulação Cardíaca Artificial/efeitos adversos , Desfibriladores Implantáveis , Cardioversão Elétrica/efeitos adversos , Cardioversão Elétrica/instrumentação , Técnicas Eletrofisiológicas Cardíacas/métodos , Marca-Passo Artificial , Falha de Prótese , Tecnologia de Sensoriamento Remoto/instrumentação , Potenciais de Ação , Idoso , Idoso de 80 Anos ou mais , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/fisiopatologia , Diagnóstico Precoce , Feminino , Frequência Cardíaca , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Desenho de Prótese , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Resultado do TratamentoRESUMO
BACKGROUND: Ambulatory measurement of intrathoracic impedance (ITI) with an implanted device may detect increases in pulmonary fluid retention early, but the clinical utility of this method is not well established. The goal of this study was to test whether conventional ITI-derived parameters can diagnose fluid retention that may cause early stage heart failure (HF). METHODS AND RESULTS: HF patients implanted with high-energy devices with OptiVol (Medtronic) monitoring were enrolled in this study. Patients were monitored remotely. At both baseline and OptiVol alert, patients were assessed on standard examinations, including analysis of serum brain natriuretic peptide (BNP). From April 2010 to August 2011, 195 patients from 12 institutes were enrolled. There were 154 primary OptiVol alert events. BNP level at the alerts was not significantly different from that at baseline. Given that ITI was inversely correlated with log BNP, we added a criterion specifying that the OptiVol alert is triggered only when ITI decreases by ≥4% from baseline. This change improved the diagnostic potential of increase in BNP at OptiVol alert (sensitivity, 75%; specificity, 88%). CONCLUSIONS: BNP increase could not be identified based on OptiVol alert. Decrease in ITI ≥4% compared with baseline, in addition to the alert, however, may be a useful marker for the likelihood of HF (Clinical trial info: UMIN000003351).
Assuntos
Cardiografia de Impedância/métodos , Alarmes Clínicos , Insuficiência Cardíaca/prevenção & controle , Peptídeo Natriurético Encefálico/sangue , Edema Pulmonar/diagnóstico , Doença Aguda , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Biomarcadores/sangue , Terapia de Ressincronização Cardíaca , Cardiografia de Impedância/instrumentação , Fármacos Cardiovasculares/uso terapêutico , Terapia Combinada , Desfibriladores Implantáveis , Impedância Elétrica , Feminino , Cardiopatias/sangue , Cardiopatias/tratamento farmacológico , Cardiopatias/fisiopatologia , Cardiopatias/cirurgia , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Edema Pulmonar/sangue , Edema Pulmonar/complicações , Edema Pulmonar/fisiopatologia , Curva ROC , Telemedicina/instrumentação , Veia Cava Inferior/ultraestrutura , Aumento de PesoRESUMO
BACKGROUND: Endothelial function is a prognostic predictor in patients undergoing percutaneous coronary intervention (PCI). However, in an era with widespread use of drug-eluting stents, the clinical relevance of endothelial dysfunction on restenosis in patients undergoing PCI has not been fully evaluated. METHODS: This study included 80 patients with stable angina pectoris. Flow-mediated dilation (FMD) of the brachial artery was examined 1 week after PCI. Patients were retrospectively followed-up for an average of 21 months after PCI. The primary endpoints included cardiac death, nonfatal myocardial infarction, stroke, coronary revascularization, and critical limb ischemia. RESULTS: A drug-eluting stent was used in 58 patients and a cardiovascular event was recorded in 34 patients during follow-up. The incidence of all cardiovascular diseases was significantly greater in the low FMD (median FMD <4.2%) than the high FMD (median FMD ≥4.2%) group (60% vs. 25%, p <0.01). Furthermore, the incidence of coronary revascularization was significantly higher in the low than the high FMD group (p = 0.02), while the incidence of in-stent restenosis did not differ between the two groups. Cox regression analysis showed that low FMD was an independent predictor of cardiovascular events (hazard ratio: 2.77, 95% confidence interval: 1.23 to 6.19, p = 0.01). CONCLUSIONS: Impaired brachial artery FMD independently predicts long-term cardiovascular events after PCI in the era of drug-eluting stents.
Assuntos
Angina Estável/terapia , Artéria Braquial/fisiopatologia , Doença da Artéria Coronariana/terapia , Stents Farmacológicos , Endotélio Vascular/fisiopatologia , Intervenção Coronária Percutânea/instrumentação , Vasodilatação , Idoso , Angina Estável/diagnóstico , Angina Estável/mortalidade , Angina Estável/fisiopatologia , Distribuição de Qui-Quadrado , Doença da Artéria Coronariana/diagnóstico , Doença da Artéria Coronariana/mortalidade , Doença da Artéria Coronariana/fisiopatologia , Reestenose Coronária/etiologia , Reestenose Coronária/fisiopatologia , Estado Terminal , Feminino , Humanos , Isquemia/etiologia , Isquemia/fisiopatologia , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Infarto do Miocárdio/etiologia , Infarto do Miocárdio/fisiopatologia , Intervenção Coronária Percutânea/efeitos adversos , Intervenção Coronária Percutânea/mortalidade , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Fatores de Risco , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/fisiopatologia , Fatores de Tempo , Resultado do TratamentoRESUMO
BACKGROUND: Excess visceral adipose tissue (VAT) is closely associated with the presence of coronary artery plaques that are vulnerable to rupture. Patients with diabetes mellitus (DM) have more VAT than patients without DM, but the extent to which VAT contributes to the characteristics of coronary plaques before and after the development of DM is not fully understood. METHODS: We retrospectively evaluated 456 patients (60% male, age 64 ± 16 years) who were suspected to have cardiovascular disease and underwent 64-slice computed tomography angiography (CTA). Seventy-one (16%) patients had vulnerable plaques (CT density < 50 Hounsfield Units, positive remodeling index > 1.05, and adjacent spotty areas of calcification). RESULTS: Patients were divided into tertiles according to the VAT area. There were stepwise increases in noncalcified and vulnerable plaques with increasing tertiles of VAT area in patients without DM, but not in patients with DM. Multivariate analysis showed that a larger VAT area was significantly associated with a higher risk of vulnerable plaque in patients without DM (odds ratio 3.17, 95% confidence interval 1.08-9.31, p = 0.04), but not in patients with DM. CONCLUSIONS: The VAT area is associated with the characteristics of coronary plaques on CTA in patients without DM, but not in patients with DM. VAT may be a significant cardiometabolic risk factor that is associated with plaque vulnerability before the development of DM. CTA findings may help to improve risk stratification in such patients.
Assuntos
Diabetes Mellitus/diagnóstico por imagem , Diabetes Mellitus/epidemiologia , Gordura Intra-Abdominal/diagnóstico por imagem , Placa Aterosclerótica/diagnóstico por imagem , Placa Aterosclerótica/epidemiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Diabetes Mellitus/diagnóstico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada Multidetectores/métodos , Placa Aterosclerótica/diagnóstico , Estudos Retrospectivos , Adulto JovemRESUMO
Peptide uptake by plant roots from degraded soybean-meal products was analyzed in Brassica rapa and Solanum lycopersicum. B. rapa absorbed about 40% of the initial water volume, whereas peptide concentration was decreased by 75% after 24 h. Analysis by reversed-phase HPLC showed that number of peptides was absorbed by the roots during soaking in degraded soybean-meal products for 24 h. Carboxyfluorescein-labeled root hair-promoting peptide was synthesized, and its localization, movement, and accumulation in roots were investigated. The peptide appeared to be absorbed by root hairs and then moved to trichoblasts. Furthermore, the peptide was moved from trichoblasts to atrichoblasts after 24 h. The peptide was accumulated in epidermal cells, suggesting that the peptide may have a function in both trichoblasts and atrichoblasts.
Assuntos
Peptídeos/farmacocinética , Raízes de Plantas/metabolismo , Brassica rapa , Epiderme Vegetal/metabolismoRESUMO
In the latent pro-form of matrix metalloproteinase 7 (MMP-7), the cysteine residue in the pro-peptide binds the active-site zinc ion. Hence, recombinant active MMP-7 was prepared from pro-MMP-7 by modification of this cysteine residue with a mercuric reagent. In this study, mature MMP-7 was expressed in Escherichia coli as inclusion bodies, solubilized, and refolded with 1 M L-arginine. The purified product was indistinguishable from the one prepared from pro-MMP-7 as assessed by hydrolysis of (7-methoxycoumarin-4-yl)acetyl-L-Pro-L-Leu-Gly-L-Leu-[N(3)-(2,4-dinitrophenyl)-L-2,3-diaminopropionyl]-L-Ala-L-Arg-NH(2).
Assuntos
Escherichia coli/genética , Metaloproteinase 7 da Matriz/biossíntese , Metaloproteinase 7 da Matriz/isolamento & purificação , Engenharia de Proteínas/métodos , Redobramento de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Sequência de Aminoácidos , Arginina/farmacologia , Sequência de Bases , Escherichia coli/citologia , Expressão Gênica , Humanos , Concentração de Íons de Hidrogênio , Corpos de Inclusão/genética , Metaloproteinase 7 da Matriz/química , Metaloproteinase 7 da Matriz/metabolismo , Redobramento de Proteína/efeitos dos fármacos , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , SolubilidadeRESUMO
To construct an efficient lipid-containing wastewater treatment system, microorganisms that degrade lipids efficiently were isolated from various environmental sources. Strain DW2-1 showed the highest rate of degradation of 1% (w/v) salad oil among the isolated strains. Strain DW2-1 was identified as Burkholderia sp. and designated Burkholderia sp. DW2-1. The rate of degradation of salad oil, olive oil, sesame oil, and beef tallow by strain DW2-1 were 96.7%, 92.3%, 90.1% and 77.4%, respectively, during a 48-h cultivation. Strain DW2-1 grew well in a synthetic wastewater medium (>1 x 10(10) colony forming unit [CFU]/ml) between 20 degrees C and 38 degrees C, and its rate of degradation of salad oil was above 90% after a 48-h cultivation. The lipase and biosurfactant (BSF) activities of strain DW2-1 after a 48-h cultivation were 1720 U/l and 480 U/ml, respectively. In continuous cultures for lipid-containing wastewater treatment, DW2-1 was stably maintained and degraded more than 90% of salad oil during a 7-d cultivation.
Assuntos
Burkholderia/crescimento & desenvolvimento , Óleos de Plantas/metabolismo , Eliminação de Resíduos Líquidos , Poluentes da Água/metabolismo , Purificação da Água , Proteínas de Bactérias/metabolismo , Burkholderia/isolamento & purificação , Lipase/metabolismo , Tensoativos/metabolismoRESUMO
Improvement of phosphorus circulation in the soil is necessary to enhance phosphorus availability to plants. Phosphorus circulation activity is an index of soil's ability to supply soluble phosphorus from organic phosphorus in the soil solution. To understand the relationship among phosphorus circulation activity; bacterial biomass; pH; and Fe, Al, and Ca concentrations (described as mineral concentration in this paper) in agricultural soil, 232 soil samples from various agricultural fields were collected and analyzed. A weak relationship between phosphorus circulation activity and bacterial biomass was observed in all soil samples (R² = 0.25), and this relationship became significantly stronger at near-neutral pH (6.0-7.3; R² = 0.67). No relationship between phosphorus circulation activity and bacterial biomass was observed at acidic (pH < 6.0) or alkaline (pH > 7.3) pH. A negative correlation between Fe and Al concentrations and phosphorus circulation activity was observed at acidic pH (R² = 0.72 and 0.73, respectively), as well as for Ca at alkaline pH (R² = 0.64). Therefore, bacterial biomass, pH, and mineral concentration should be considered together for activation of phosphorus circulation activity in the soil. A relationship model was proposed based on the effects of bacterial biomass and mineral concentration on phosphorus circulation activity. The suitable conditions of bacterial biomass, pH, and mineral concentration for phosphorus circulation activity could be estimated from the relationship model.
RESUMO
T wave oversensing (TWOS) is a common cause of inappropriate implantable cardioverter-defibrillator (ICD) therapies. Various algorithms to avoid inappropriate ICD therapy are available; however, they are not helpful to avoid TWOS. Although the reproduction of TWOS is useful to resolve the problem of TWOS, it is sometimes difficult to reproduce TWOS. We report two cases of inappropriate ICD therapy due to TWOS, which were induced only by body twisting. We can successfully manage the device based on the evidence of reproduced TWOS.
RESUMO
BACKGROUND: Ambulatory measurement of intrathoracic impedance (ITI) with an implanted device has potential to assess fluid accumulation in patients with heart failure (HF), but it has failed to reduce HF-related hospitalization because of a high false-positive rate. OBJECTIVE: We aimed to examine whether a modified algorithm (OptiVol 2.0) could reduce false-positive HF events documented in our multicenter trial (MOMOTARO). METHODS: The MOMOTARO trial assessed the potential that fluid index could predict fluid accumulation and therefore HF. The MOMOTARO trial assessed whether HF events could be detected based on fluid accumulation as assessed by fluid index. We re-analyzed raw data of ITI trends of the threshold-crossing events with the modified algorithm. RESULTS: The study consisted of 195 patients who had been implanted with a high-energy device. During a mean follow-up period of 658±165 days, there were 154 primary HF events detected by the previous algorithm (OptiVol 1.0). With the previous algorithm, there was no significant difference in log concentration of brain natriuretic peptide (BNP) between baseline and alert (p=0.21). Among 150 alerts of the previous algorithm, only 37 reached the threshold by the modified algorithm, and log BNP was significantly higher in these 37 events compared with the baseline value (2.40±0.46 vs. 2.27±0.52, p<0.01). CONCLUSION: Our simulation study demonstrates that fluid index calculated with the modified algorithm reduces the number of false-positive threshold-crossing HF events and is promising for accurate diagnosis of fluid accumulation in patients.
Assuntos
Algoritmos , Cardiografia de Impedância , Insuficiência Cardíaca/diagnóstico , Idoso , Impedância Elétrica , Feminino , Insuficiência Cardíaca/sangue , Hospitalização , Humanos , Masculino , Pessoa de Meia-Idade , Peptídeo Natriurético Encefálico/sangueRESUMO
The relationship between the autodegradation and thermostability of thermolysin (TLN) was studied. Four autodegradation sites in TLN were identified in the presence of Ca(2+). One of the sites was identified as Gly(154)-Leu(155), and Leu(155) was substituted with various amino acids, X = Ala, Ser, Phe, and Gly, by site-directed mutagenesis. The thermostability at 80 degrees C increased with the amino acid substitutions in the order of Ala>Phe>Ser>Gly>Leu (WT TLN). An additional autodegradation fragment that was not observed with WT TLN appeared for all mutant TLNs examined. The autodegradation site shifted from the Gly(154)-Leu(155) bond to the X(155)-Ile(156) one with the mutation at Leu(155). Furthermore, the Ile(164)-Asp(165) bond was recognized newly as an autodegradation site in the mutant TLNs for the production of AF3'.
Assuntos
Substituição de Aminoácidos/genética , Termolisina/metabolismo , Sequência de Aminoácidos/fisiologia , Aminoácidos/química , Aminoácidos/genética , Bacillus/enzimologia , Sítios de Ligação/genética , Cloreto de Cálcio/química , Dicroísmo Circular , Dipeptídeos/química , Dipeptídeos/metabolismo , Eletroforese em Gel de Poliacrilamida , Estabilidade Enzimática/genética , Escherichia coli/genética , Vetores Genéticos/genética , Temperatura Alta , Cinética , Leucina/química , Leucina/genética , Modelos Químicos , Modelos Moleculares , Mutagênese Sítio-Dirigida , Fragmentos de Peptídeos/análise , Mutação Puntual/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Temperatura , Termolisina/química , Termolisina/genéticaRESUMO
We examined the effects of D- or L-amino acids on the stimulation of Brassica rapa roots. When 6.7 microM of D-methionine (D-Met) or L-methionine (L-Met) was applied, root hair numbers increased. L-Met (above concentration of 67.0 microM) caused the tip of roots to spiral. When CoCl2 (ethylene synthesis inhibitor) was added into the medium, L-Met lost its activity but COCl2 did not inhibit the bioactivity of D-Met.
RESUMO
The degradation of alkylcyclohexane by Acinetobacter sp. ODDK71 was investigated. Strain ODDK71 degraded alkylcyclohexanes (alkyl side chain length of > or = 12) by co-metabolism when hexadecane was used as a growth substrate. GGMS analysis of co-metabolized products from dodecylcyclohexane suggests that strain ODDK71 degraded dodecylcyclohexane via a ring oxidation and an alkyl side chain oxidation pathways. The ring oxidation pathway of dodecylcyclohexane is a novel pathway of microbial degradation of dodecylcyclohexane.
RESUMO
BACKGROUND: Residual risk of cardiovascular disease from increased small dense low-density lipoprotein (sdLDL)-cholesterol levels and low n-3 polyunsaturated fatty acid (PUFA) levels is a considerable therapeutic issue. The purpose of this study was to evaluate the effect of ezetimibe as an add-on to statins and supplemental eicosapentaenoic acid (EPA) on sdLDL cholesterol and absorption of EPA in patients with coronary artery disease. METHODS: The study population consisted of ten male patients who were concurrently receiving statins and EPA 1,800 mg/day. Serum lipids and PUFAs, including EPA and arachidonic acid, were measured in blood samples collected before ezetimibe (baseline), 4 weeks after starting 10-mg/day ezetimibe, and 4 weeks after discontinuing ezetimibe. RESULTS: Ezetimibe significantly decreased sdLDL-cholesterol levels after 4 weeks of treatment (baseline 35 ± 13 mg/dl; treatment 27 ± 9 mg/dl), but the levels returned to baseline after discontinuation of ezetimibe (37 ± 13 mg/dl). The concentration of EPA did not significantly change during the study. CONCLUSION: Ezetimibe shows great promise as an add-on therapy to statins to reduce sdLDL-cholesterol-related residual risk of cardiovascular disease without affecting absorption of supplemental EPA in patients with coronary artery disease.
Assuntos
Anticolesterolemiantes/uso terapêutico , Azetidinas/uso terapêutico , LDL-Colesterol/sangue , Doença da Artéria Coronariana/sangue , Doença da Artéria Coronariana/tratamento farmacológico , Ácido Eicosapentaenoico/farmacocinética , Idoso , Quimioterapia Combinada , Ezetimiba , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Absorção Intestinal/efeitos dos fármacos , Masculino , Projetos Piloto , Estudos ProspectivosRESUMO
Accumulations of inorganic nitrogen (NH4âº, NO2â», and NO3â») were analyzed to evaluate the nitrogen circulation activity in 76 agricultural soils. Accumulation of NH4⺠was observed, and the reaction of NH4âºâ NO2â» appeared to be slower than that of NO2â» â NO3â» in agricultural soil. Two autotrophic and five heterotrophic ammonia-oxidizing bacteria (AOB) were isolated and identified from the soils, and the ammonia-oxidizing activities of the autotrophic AOB were 1.0 × 10³-1.0 × 106 times higher than those of heterotrophic AOB. The relationship between AOB number, soil bacterial number, and ammonia-oxidizing activity was investigated with 30 agricultural soils. The ratio of autotrophic AOB number was 0.00032-0.26% of the total soil bacterial number. The soil samples rich in autotrophic AOB (>1.0 × 104 cells/g soil) had a high nitrogen circulation activity, and additionally, the nitrogen circulation in the agricultural soil was improved by controlling the autotrophic AOBs.
Assuntos
Amônia/metabolismo , Bactérias/metabolismo , Nitrogênio/química , Solo/química , Agricultura , Processos Autotróficos , Nitrificação , Nitrogênio/análise , Microbiologia do SoloRESUMO
A real-time PCR quantification method for indigenous hydrocarbon-degrading bacteria (HDB) carrying the alkB gene in the soil environment was developed to investigate their distribution in soil. The detection limit of indigenous HDB by the method was 1 × 10(6) cells/g-soil. The indigenous HDB were widely distributed throughout the soil environment and ranged from 3.7 × 10(7) to 5.0 × 10(8) cells/g-soil, and the ratio to total bacteria was 0.1-4.3 %. The dynamics of total bacteria, indigenous HDB, and Rhodococcus erythropolis NDKK6 (carrying alkB R2) during bioremediation were analyzed. During bioremediation with an inorganic nutrient treatment, the numbers of these bacteria were slightly increased. The numbers of HDB (both indigenous bacteria and strain NDKK6) were gradually decreased from the middle stage of bioremediation. Meanwhile, the numbers of these bacteria were highly increased and were maintained during bioremediation with an organic nutrient. The organic treatment led to activation of not only the soil bacteria but also the HDB, so an efficient bioremediation was carried out.
Assuntos
Hidrocarbonetos/metabolismo , Rhodococcus/metabolismo , Microbiologia do Solo , Alcanos/metabolismo , Carga Bacteriana , Biodegradação Ambiental , Biota , Carbono/metabolismo , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Petróleo/metabolismo , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismo , Rhodococcus/genética , Solo , Fatores de TempoRESUMO
To better understand the phosphorus (P) cycling in an agricultural soil environment, amounts of total, organic and inorganic P in 10 agricultural soil samples were analyzed. Since a large proportion (57.8%) of the total P in the soils was in organic form, a method was developed to evaluate the mineralization rate of organic P in the soil by adding phytate to the soil and analyzing the change in water-soluble P (WSP) content after incubating it for 3 days. Moreover, the relationship between the phytate mineralization activity and bacterial biomass in 60 agricultural soils was also investigated, where the phytate mineralization activity ranged from 0 to 61.7% (average: 18.8%), and the R² value between phytate mineralization activity and indigenous bacterial biomass was 0.11 only. Phytate-degrading bacteria were isolated from the soil environment, and identified as Pseudomonas rhodesiae JT29, JT32, JT33, JT34, JT35, Pseudomonas sp. JT30, and Flavobacterium johnsoniae JT31. When P. rhodesiae JT29 and F. johnsoniae JT31 were inoculated into the agricultural soils, the phytate mineralization activities were increased up to 16 and 27 times, respectively. It was concluded that promotion of effective phytate-degrading bacterial strains could improve the sustainable P management in the agricultural soils.
Assuntos
Flavobacterium/isolamento & purificação , Flavobacterium/metabolismo , Ácido Fítico/metabolismo , Pseudomonas/isolamento & purificação , Pseudomonas/metabolismo , Microbiologia do Solo , Biomassa , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Flavobacterium/classificação , Flavobacterium/crescimento & desenvolvimento , Dados de Sequência Molecular , Fósforo/análise , Pseudomonas/classificação , Pseudomonas/crescimento & desenvolvimento , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Solo/químicaRESUMO
The autodegradation-resistant mutant thermolysins (TLNs), L155A (Leu(155) to Ala) and L155S (Leu(155) to Ser), were previously constructed by site-directed mutagenesis to enhance thermostability. These mutations suppressed autodegradation at position 154-155, resulting in increased thermostability. However, a new autodegradation site became apparent in these mutant TLNs, at position 155-156. In this study, further stabilization of the mutant TLNs to suppress this new autodegradation was attempted by the substitution of Ile(156) to Asp and Val (L155A-I156N, L155A-I156V, L155S-I156N, and L155S-I156V). SDS-PAGE analysis showed that the autodegradation at 155-156 of all double-mutant TLNs was suppressed. Thermostability at 80 °C was enhanced in all double-mutant TLNs (half-life at 80 °C: WT, 18.3 min; L155A, 25.0 min; L155S, 24.0 min; L155A-I156N, 60.8 min; L155A-I156V, 62.4 min; L155S-I156N, 93.3 min; and L155S-I156V, 40.0 min), and k (cat)/K (m) values were: WT, 220; L155A, 240; L155S, 123; L155A-I156N, 62; L155A-I156V, 760; L155S-I156N, 240; and L155S-I156V, 520 min(-1) mM(-1).