Electrochemical control of redox potential affects methanogenesis of the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus.

To investigate the precise effect of the redox potential on the methanogenesis of the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus by using an electrochemical redox controlling system without adding oxidizing or reducing agents. A bioelectrochemical system was applied to control the redox conditions in culture and to measure the methane-producing activity of M. thermautotrophicus at a constant potential from +0·2 to -0·8 V (vs Ag/AgCl). Methane production and growth of M. thermautotrophicus were 1·6 and 3·5 times increased at -0·8 V, compared with control experiments without electrolysis, respectively, while methanogenesis was suppressed between +0·2 and -0·2 V. A clear relationship between an electrochemically regulated redox potential and methanogenesis was revealed.

Diffusion-weighted imaging for predicting new compression fractures following percutaneous vertebroplasty.

BACKGROUND: Percutaneous vertebroplasty (PVP) is a technique that structurally stabilizes a fractured vertebral body. However, some patients return to the hospital due to recurrent back pain following PVP, and such pain is sometimes caused by new compression fractures. PURPOSE: To investigate whether the apparent diffusion coefficient (ADC) of adjacent vertebral bodies as assessed by diffusion-weighted imaging before PVP could predict the onset of new compression fractures following PVP. MATERIAL AND METHODS: 25 patients with osteoporotic compression fractures who underwent PVP were enrolled in this study. ADC was measured for 49 vertebral bodies immediately above and below each vertebral body injected with bone cement before and after PVP. By measuring ADC for each adjacent vertebral body, ADC was compared between vertebral bodies with a new compression fracture within 1 month and those without new compression fractures. In addition, the mean ADC of adjacent vertebral bodies per patient was calculated. RESULTS: Mean preoperative ADC for the six adjacent vertebral bodies with new compression fractures was 0.55 x 10(-3) mm(2)/s (range 0.36-1.01 x 10(-3) mm(2)/s), and for the 43 adjacent vertebral bodies without new compression fractures 0.20 x 10(-3) mm(2)/s (range 0-0.98 x 10(-3) mm(2)/s) (P < 0.001). Mean preoperative ADC for the six patients with new compression fractures was 0.55 x 10(-3) mm(2)/s (range 0.21-1.01 x 10(-3) mm(2)/s), and that for the 19 patients without new compression fractures 0.17 x 10(-3) mm(2)/s (range 0.01-0.43 x 10(-3) mm(2)/s) (P < 0.001). CONCLUSION: The ADC of adjacent vertebral bodies as assessed by diffusion-weighted imaging before PVP might be one of the predictors for new compression fractures following PVP.

Development of a novel artificial medium based on utilization of algal photosynthetic metabolites by symbiotic heterotrophs.

AIMS: (i) Quantitative and qualitative analyses of photosynthetic metabolites of Chlorella sorokiniana and elucidation of the mechanism of their utilization by algal symbionts. (ii) Development of artificial medium that imitates photoautotroph-heterotroph interaction and investigation of its suitability for isolation of novel microbes from the environment. METHODS AND RESULTS: Various components, including free dissolved carbohydrates, nitrogenous compounds and vitamin, were detected and together contributed 11.1% (as carbon content) of the total photosynthetic metabolites in the medium. Utilization of these photosynthetic metabolites in algal culture broth by algal symbionts was studied. Many symbionts showed specific utilization patterns. A novel artificial extracellular released organic carbon medium, which imitated the nutritional conditions surrounding algae, was developed based on the pattern of utilization of the algal metabolites by the symbiotic heterotrophs. About 42.9% of the isolates were closely related to photoautotrophic-dependent and oligotrophic bacteria. CONCLUSIONS: With the novel artificial medium, it was possible to selectively isolate some bacterial strains. SIGNIFICANT AND IMPACT OF THE STUDY: Synthetic bacterial growth medium is an important and basic tool for bacterial isolation from environmental samples. The current study shows that preferential separation of typical bacterial subset can be achieved by using artificial medium that mimics photosynthetic metabolites.

Gadolinium-enhanced magnetic resonance imaging after percutaneous vertebroplasty does not improve the short-term prediction of new compression fractures.

PURPOSE: To investigate the relationships between contrast-enhanced magnetic resonance imaging (MRI) findings and new compression fractures occurring after percutaneous vertebroplasty (PVP) in order to determine the necessity of contrast-enhanced MRI. MATERIAL AND METHODS: The material comprised 13 consecutive patients (27 vertebrae) with compression fractures who underwent vertebroplasty. Twenty-nine adjacent vertebrae were monitored for new compression fractures. We performed contrast-enhanced MRI within the 5 days following PVP. RESULTS: The 29 adjacent vertebrae displayed 10 enhanced lesions and 19 vertebral bodies without enhancement-unenhanced lesions on MRI within the 5 days after PVP. In 4 out of 10 vertebrae, enhanced lesions were seen within the 5 days after PVP, but no abnormalities were seen on preoperative MRI. In these 4 vertebrae, new compression fractures were seen within the 1 month following PVP. In the other 6 vertebrae, enhanced lesions were seen within the 5 days after PVP, and these signal changes were detected by preoperative MRI in the same area. In 3 of these 6 vertebrae, new compression fractures occurred at 4, 8, and 9 months after PVP, respectively. However, all of the enhanced lesions were detectable on unenhanced MRI, which was conducted at the same time as enhanced MRI. CONCLUSION: New compression fractures after PVP may be predicted with early postoperative MRI. Contrast-enhanced MRI does not improve detection of the new lesions.

Composition of the sheath produced by the green alga Chlorella sorokiniana.

AIMS: To investigate the chemical characterization of the mucilage sheath produced by Chlorella sorokiniana. METHODS AND RESULTS: Algal mucilage sheath was hydrolysed with NaOH, containing EDTA. The purity of the hydrolysed sheath was determined by an ATP assay. The composition of polysaccharide in the sheath was investigated by high-performance anion-exchange chromatography with pulsed amperometric detection. Sucrose, galacturonic acid, xylitol, inositol, ribose, mannose, arabinose, galactose, rhamnose and fructose were detected in the sheath as sugar components. Magnesium was detected in the sheath as a divalent cation using inductively coupled argon plasma. The sheath matrix also contained protein. CONCLUSIONS: It appears that the sheath is composed of sugars and metals. Mucilage sheath contains many kinds of saccharides that are produced as photosynthetic metabolites and divalent cations that are contained in the culture medium. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on chemical characterization of the sheath matrix produced by C. sorokiniana.

An immunoassay for small analytes with theoretical detection limits.

A flow-based immunoassay that uses microspheres as the solid phase accomplished the theoretical limit of detectability achievable with the antibody. An equilibrated mixture of anti-estriol monoclonal antibody and estriol was briefly exposed to a bead pack containing immobilized estriol in a flow cell. A small portion of free antibody was separated rapidly from the mixture by binding it to immobilized hormone, but the antibody-hormone complex was kinetically excluded from binding. This rapid separation prevented shift in the equilibrium of the liquid phase binding. Signals were generated by labeling the separated antibodies on the beads with a Cy5-conjugated antispecies secondary antibody. By labeling after the separation step, perturbing the liquid-phase or solid-phase binding was prevented. This assay allowed the reduction of the concentration of primary antibody by continuously accumulating free antibody onto the beads prior to quantification and, thus, offered ideal conditions to achieve theoretical limits of detectability. The optimum achievable dynamic range of this immunoassay was 4-300 pM. Because the proportion of free anti-estriol antibody in the mixture was controlled by the Kd of the antibody-estriol interaction, when the concentration of the antibody was below the Kd, the smallest detectable estriol concentration approached the theoretical limit of detectability achievable with this antibody.

High density cultivation of two strains of iron-oxidizing bacteria through reduction of ferric iron by intermittent electrolysis.

Electrolytic cultivation was applied to Leptospirillum ferrooxidans strains P3A and CF27, which use ferrous iron to respire aerobically. Ferrous iron was supplied to the bacteria by intermittent electrolytic reduction of ferric iron as electron shuttle using an electrode. The yield of L. ferrooxidans and strain CF27 reached 20- and 50-fold, respectively, higher density than were achievable yields without electrolysis. The time required to obtain high density depended not on the growth ratio, but rather on the original growth rate of each strain.

Extension of logarithmic growth of Thiobacillus ferrooxidans by potential controlled electrochemical reduction of Fe(III).

In this study, we demonstrated that the period of logarithmic growth for Thiobacillus ferrooxidans could be extended when optimal conditions for cell growth were maintained using potential controlled electrochemical cultivation with sufficient aeration. The optimal pH and Fe(II) concentration for the electrolytic cultivation were determined to be 2.0 and 150 mM, respectively. When the potential was set to 0.0V vs Ag/AgCl, the Pt electrode reduced Fe(III) to Fe(II) with an efficiency of 95%. A porous glass microbubble generator was used to maintain adequate levels of dissolved oxygen, which was the electron acceptor for T. ferrooxidans when the cell density in the medium was high. Under these conditions, cells at an initial density of 10(7) cells/mL grew logarithmically for 4days until the cell density was 4 x 10(9) cells/mL. This corresponded to a period of logarithmic growth that was 3 times longer than was observed in batch cultures without electrolysis. In addition, the final cell density reached 10(10) cells/mL after 6 days of electrochemical cultivation, which was a 50-fold increase over conventional batch culture. Under conditions of increasing cell density, potentiostatic electrolysis made it possible to remove Fe(III), which causes product inhibition, at an increasing rate and to correspondingly increase the production rate of Fe(II), which is the electron donor for T. ferrooxidans. Thus, our cultivation system provides a sufficient supply of electron donor and acceptor for T. ferrooxidans, thereby elongating the period of logarithmic growth and producing very high cell densities.

A novel mineral flotation process using Thiobacillus ferrooxidans.

Oxidative leaching of metals by Thiobacillus ferrooxidans has proven useful in mineral processing. Here, we report on a new use for T. ferrooxidans, in which bacterial adhesion is used to remove pyrite from mixtures of sulfide minerals during flotation. Under control conditions, the floatabilities of five sulfide minerals tested (pyrite, chalcocite, molybdenite, millerite, and galena) ranged from 90 to 99%. Upon addition of T. ferrooxidans, the floatability of pyrite was significantly suppressed to less than 20%. In contrast, addition of the bacterium had little effect on the floatabilities of the other minerals, even when they were present in relatively large quantities: their floatabilities remained in the range of 81 to 98%. T. ferrooxidans thus appears to selectively suppress pyrite floatability. As a consequence, 77 to 95% of pyrite was removed from mineral mixtures while 72 to 100% of nonpyrite sulfide minerals was recovered. The suppression of pyrite floatability was caused by bacterial adhesion to pyrite surfaces. When normalized to the mineral surface area, the number of cells adhering to pyrite was significantly larger than the number adhering to other minerals. These results suggest that flotation with T. ferrooxidans may provide a novel approach to mineral processing in which the biological functions involved in cell adhesion play a key role in the separation of minerals.

Clinical outcome of stenting in superior vena cava syndrome associated with malignant tumors. Comparison with conventional treatment.

PURPOSE: We analyzed the clinical outcome of treatment with the expandable metallic stent (EMS) for the superior vena cava (SVC) syndrome associated with malignant tumors, and the results were compared with those of radiotherapy. MATERIAL AND METHODS: Of 33 patients with the SVC syndrome, 23 were treated by Gianturco EMS placement and 10 were treated by radiotherapy and/or chemotherapy alone. Of the 23 EMS patients, 11 had treatment before EMS placement and 12 had no treatment before EMS placement. RESULTS: After stenting, the clinical symptoms disappeared in 78% (18/23) of the patients, i.e. in 50% of the patients with intraluminal tumors, and in 93% of those with extrinsic compression. The clinical symptoms improved in 80% of patients who received radiotherapy. The mean duration of survival was 145 days in patients who underwent stenting, and 146 days in those receiving radiotherapy. However, the survival period differed significantly between patients with intraluminal tumors (44.9 days) and those with extrinsic compression (198.6 days). Between patients with previous treatment and those with no previous treatment, there was no significant difference in response rate or in survival period which were 82% versus 75%, and 127 days versus 162 days, respectively. CONCLUSION: The clinical symptoms showed similar improvement in patients receiving EMS placement or radiotherapy. EMS placement was effective in relieving clinical symptoms in patients who had failed to respond to radiotherapy.

Acutely severe myocarditis successfully treated by percutaneous cardiopulmonary support applied by a newly developed heparin-binding oxygenator and circuits.

The feasibility of using the heparin-bound percutaneous cardiopulmonary support system (PCPS) for prolonged extracorporeal circulation in patients with acute severe myocarditis is demonstrated. The case histories of 2 patients with cardiogenic shock caused by acute myocarditis are presented; both were successfully treated with long-term PCPS using a newly developed heparin-binding oxygenator and circuits without changing the oxygenator. The courses of both patients remain uneventful more than 12 months after discharge. We also discuss the clinical aspects of using heparin-bound PCPS in patients with acute severe myocarditis.

Percutaneous endoscopic retrieval and replacement of a knitted (Ultraflex) biliary stent.

A knitted (Ultraflex) biliary stent became obstructed after 5 months causing recurrent jaundice in a 92-year-old man with pancreatic cancer. The obstructed stent was successfully removed percutaneously by retrieval forceps under guidance by an 8.4 Fr fiberoptic biliary endoscope. A new stent was placed. No complications were encountered.

Further ST elevation at reperfusion by direct percutaneous transluminal coronary angioplasty predicts poor recovery of left ventricular systolic function in anterior wall AMI.

Some patients with acute myocardial infarction (AMI) develop further ST elevation at reperfusion by percutaneous transluminal coronary angioplasty (PTCA). This study reports the ST deviation at reperfusion by direct PTCA in relation to the clinical factors and the recovery of left ventricular (LV) systolic function. Fifty-two patients with anterior wall AMI were treated with direct PTCA. They were classified into the following 3 groups according to the change in ST elevation at reperfusion: increase of > or = 20% (ST reelevation); reduction of > or = 20% (ST resolution); and the other (ST no change). Angina pectoris preceding AMI occurred less often in the ST reelevation group (ST reelevation group, 38%; ST no change group, 81%; ST resolution group, 70%; p < 0.05). Recovery of LV ejection fraction during the first month after direct PTCA was significantly poor in the ST reelevation group in contrast to the ST resolution group (ST reelevation group, -6.3 +/- 13%; ST no change group, 18 +/- 20%; ST resolution group, 45 +/- 29%; p < 0.0001). The change in ST elevation at reperfusion was an index predicting the recovery of LV systolic function in the reperfusion by direct PTCA.

Sulfur-binding protein of flagella of Thiobacillus ferrooxidans.

The sulfur-binding protein of Thiobacillus ferrooxidans ATCC 23270 was investigated. The protein composition of the bacterium's cell surface changed according to the culture substrate. Sulfur-grown cells showed greater adhesion to sulfur than iron-grown cells. The sulfur-grown cells synthesized a 40-kDa surface protein which was not synthesized by iron-grown cells. The 40-kDa protein had thiol groups and strongly adhered to elemental sulfur powder. This adhesion was not disturbed by Triton X-100, which can quench hydrophobic interactions. However, adhesion was disturbed by 2-mercaptoethanol, which broke the disulfide bond. The thiol groups of the 40-kDa protein formed a disulfide bond with elemental sulfur and mediated the strong adhesion between T. ferrooxidans cells and elemental sulfur. The 40-kDa protein was located on the flagella. The location of the protein would make it possible for cells to be in closer contact with the surface of elemental sulfur powder.

Delayed improvement in skeletal muscle metabolism and exercise capacity in patients with mitral stenosis following immediate hemodynamic amelioration by percutaneous transvenous mitral commissurotomy.

The abrupt improvement in hemodynamics after successful percutaneous transvenous mitral commissurotomy (PTMC) does not immediately enhance exercise capacity. Improved exercise capacity several months after PTMC has been reported. We hypothesized that the delayed improvement in exercise capacity is due partly to the slow improvement in the metabolism of skeletal muscle. This study examined the short- and long-term effects of PTMC on exercise capacity and skeletal muscle metabolism in patients with mitral stenosis. Treadmill exercise testing with respiratory gas analysis was performed in 11 patients with symptomatic mitral stenosis before and 3, 30, and 90 days after successful PTMC. On the same schedule, forearm metabolism of high-energy phosphates was measured by magnetic resonance spectroscopy during and after handgrip exercise. Ten healthy volunteers were examined. PTMC resulted in an immediate symptomatic improvement. However, exercise capacity and skeletal muscle metabolism remained unchanged 3 days after PTMC. At 30 days after PTMC, there were significant improvements in peak oxygen consumption (p <0.05), intracellular pH at end-exercise (p <0.05), and time constant for phosphocreatine recovery (mean +/- SD 88.9 +/- 11.3 vs 106.3 +/- 11.7 seconds, p <0.01) compared with these baseline values. These improvements remained even at 90 days after PTMC. Exercise capacity improved with some time delay after immediate hemodynamic amelioration by PTMC. Long-term improvement in exercise capacity depends partly on the slowly progressing improvement in skeletal muscle metabolism after long-standing mitral stenosis.

Effects of an HMG-CoA reductase inhibitor on cytokine production by human monocytes/macrophages.

It has been reported that the HMG-CoA reductase inhibitor simvastatin does not always effectively lower plasma LDL. This drug acts to monocytes/macrophages directly and inhibits cholesterol ester accumulation in these cells. However cytokine production in macrophages when simvastatin was administrated has not been described. In this study, we examined whether simvastatin affects cytokine production in human monocyte-derived macrophages. Simvastatin at doses ranging from 10(-9) to 10(-5) M did not affect the synthesis of proinflammatory cytokines (IL-1 beta, IL-6, IL-8) from human peripheral mononuclear cells. In addition, any changes in cytokine-induced cytokine production (IL-1-induced IL-8 synthesis) were not detected after the addition of simvastatin. The present results suggest that simvastatin suppresses foam cell formation in monocyte/macrophage, without affecting the immunological or inflammatory functions of these cells.

Role of skeletal muscle metabolism in exercise capacity of patients with myocardial infarction studied by phosphorus-31 nuclear magnetic resonance.

Patients with congestive heart failure reportedly show a poor correlation between cardiac function and exercise tolerance. Recent studies have demonstrated that skeletal muscle is the main factor that limits exercise tolerance. However, the relationship between high-energy phosphate metabolism in skeletal muscle and exercise tolerance has not been well defined. Exercise capacity was assessed in 35 subjects with myocardial infarction in terms of peak oxygen consumption (peak VO2) during treadmill exercise with an analysis of expired gases. On the same day, changes in high-energy phosphates in finger flexor muscle during handgrip exercise were measured by magnetic resonance spectrometry. Phosphocreatine (PCr) utilization and the decrease in pH during handgrip exercise were significantly greater in patients with a poor exercise capacity and their time constant of recovery of PCr was prolonged. The ratios of PCr/Pi (Pi: inorganic phosphate) and PCr/HMPA (HMPA: hexamethylphosphoramide) during exercise and the time constant of recovery of PCr were significantly correlated with peak VO2. These results suggest that skeletal muscle metabolism governs exercise tolerance.