An intestinal Candida albicans model for monomicrobial and polymicrobial biofilms and effects of hydrolases and the Bgl2 ligand.

Background and Aim: Candida albicans is the most prevalent human fungal pathogen. In biofilms, C. albicans becomes more resistant to antifungal agents because of the production of an extracellular matrix (ECM) that protects the yeast cells. This study aimed to determine the effects of hydrolase enzymes and the Bgl2 ligand on monomicrobial and polymicrobial biofilms. Materials and Methods: Biofilm induction in rats was carried out using streptomycin (25 mg/kg) and gentamicin (7.5 mg/kg) administered orally once per day for 5 days. Rats were injected subcutaneously with cortisone acetate (225 mg/kg) as an immunosuppressant on day 5. In addition, rats were orally administered C. albicans for the single microbial model and a combination of C. albicans with Escherichia coli for the polymicrobial model. Following the biofilm production, the groups were treated with glucosamine (8.57 mg/kg body weight) and Achatina fulica hydrolases (1.5 mL) orally for 2 weeks. The reduction of the biofilm was measured using confocal laser scanning microscopy (CLSM). Data were analyzed using a t-test, with a significance value of 95%. Results: CLSM images revealed a strong association between C. albicans and E. coli in the polymicrobial biofilm. On the contrary, the combination treatment using glucosamine and A. fulica hydrolases reduced the ECM of the single microbial biofilm (53.58%). However, treatment effectiveness against the matrix (19.17%) was reduced in the polymicrobial model. Conclusion: There is a strong association between C. albicans and E. coli in the formation of polymicrobial biofilms. The combination of glucosamine and the A. fulica enzyme can reduce the single microbial biofilm ECM; however, it is ineffective in the polymicrobial model.

Peculiar citric acid cycle of hydrothermal vent chemolithoautotroph Hydrogenovibrio crunogenus, and insights into carbon metabolism by obligate autotrophs.

The genome sequence of the obligate chemolithoautotroph Hydrogenovibrio crunogenus paradoxically predicts a complete oxidative citric acid cycle (CAC). This prediction was tested by multiple approaches including whole cell carbon assimilation to verify obligate autotrophy, phylogenetic analysis of CAC enzyme sequences and enzyme assays. Hydrogenovibrio crunogenus did not assimilate any of the organic compounds provided (acetate, succinate, glucose, yeast extract, tryptone). Enzyme activities confirmed that its CAC is mostly uncoupled from the NADH pool. 2-Oxoglutarate:ferredoxin oxidoreductase activity is absent, though pyruvate:ferredoxin oxidoreductase is present, indicating that sequence-based predictions of substrate for this oxidoreductase were incorrect, and that H. crunogenus may have an incomplete CAC. Though the H. crunogenus CAC genes encode uncommon enzymes, the taxonomic distribution of their top matches suggests that they were not horizontally acquired. Comparison of H. crunogenus CAC genes to those present in other 'Proteobacteria' reveals that H. crunogenus and other obligate autotrophs lack the functional redundancy for the steps of the CAC typical for facultative autotrophs and heterotrophs, providing another possible mechanism for obligate autotrophy.

Phase Locking the Spin Precession in a Storage Ring.

This Letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV/c bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate (≈121 kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a 1 standard deviation range of σ=0.21 rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles.

Speciation of metals in bed sediments and water of Qaraaoun Reservoir, Lebanon.

Determination of only total element in sediments does not give an accurate estimate of the likely environmental impacts. Speciation study of metals in sediment provides information on the potential availability of metals (toxic) to biota under various environmental conditions. In water, the toxic metal specie is the free hydrated metal ion. The toxicity of metals depends especially on their chemical forms rather than their total metal content. The present study focuses on Qaraaoun Reservoir, Lebanon. Earlier studies focused only on total metal concentrations in sediment and water. The objective of this study was to determine metal speciation (Fe, Cr, Ni, Zn, Cu, Pb, Cd) in the (operationally defined) sediment chemical fractions and metal speciation in reservoir water. This would reflect on metal bioavailability and toxicity. Water samples and bed sediments were collected from nine sites during the dry season and a sequential chemical fraction scheme was applied to the <75-µm sieve sediment fraction. Metal content in each fraction was determined by the FAAS technique. The data showed that the highest percentages of total metal content in sediment fractions were for: Fe in residual followed by reducible, Cr and Ni in residual and in reducible, Cu in organic followed by exchangeable, Zn in residual and in organic, Pb in organic and carbonate, Cd was mainly in carbonate. Total metal content in water was determined by ICP-MS technique and aqueous metal speciation was predicted using AQUACHEM software interfaced to PHREEQC geochemical computer model. The water speciation data predicted that a high percentage of Pb and Ni were present as carbonate complex species and low percentages as free hydrated ions, highest percentage of Zn as carbonate complex species followed by free hydrated ion, highest percentage of Cd as free hydrated ion followed by carbonate complex species. The sensitivity attempt of free hydrated ion of Ni, Zn, Pb, and Cd in reservoir water revealed dependence of Zn and Cd on pH and alkalinity, while Ni and Pb were only dependent on pH.

Assesment of LV diastolic filling using color M-mode Doppler echocardiography: validation in new hydoraulic model.

The effect of LV properties on v(p) and the E/v(p) ratio remains a matter of debate. Therefore,the objective of this study is to explore - in a new hydraulic model - the individual contributions of LV relaxation, filling pressure and compliance in changes of E, v(p) and E/v(p) for different stages of diastolic function. A new hydraulic model, consisting of an open cylindrical LA connected to an ellipsoidal LV, is designed. E and v(p) are measured for varying values of tau (45-60-90 ms), LV compliance (0.45-1.35 ml/mmHg) and filling pressure (3-10-30 mmHg). The results are used for predicting the evolution of E, v(p) and E/v(p) during different stages of diastolic function. An increase in compliance decreases E, whereas it augments v(p). v(p) is less load-dependent than E. E decreases with delayed relaxation, increases for the case of pseudonormalisation, and becomes higher than the reference values during restrictive filling. The v(p) value is lower for the case of delayed relaxation than for the reference situation. During pseudonormalisation, the value of v(p) remains lower than the reference value but higher than the value for delayed relaxation. v(p) further decreases during restrictive filling. In conclusion, the effect of simultaneous changes in compliance and loading counterbalance changes in v(p). Therefore, under normal physiologic conditions where load and compliance are coupled, v(p) is apparently load-intensive and E/v(p) increases as filling pressure increases. Moreover, in the different stages of diastolic dysfunction, due to the interference of the co-varying relaxation, the increase in E/v(p) is more pronounced.

Validation of planar and tomographic radionuclide ventriculography by a dynamic ventricular phantom.

Although there is increasing interest in the automatic processing of tomographic radionuclide ventriculography (TRV) studies, validation is mainly limited to a comparison of TRV results with data from planar radionuclide ventriculography (PRV) or gated perfusion single photon emission computed tomography (SPECT). The aim of this study was to use a dynamic physical cardiac phantom to validate the ejection fraction (EF) and volumes from PRV and TRV studies. A new dynamic left ventricular phantom was constructed and used to obtain 21 acquisitions in the planar and tomographic mode. The directly measured volumes and EFs of the phantom during the acquisitions were considered as the gold standard for comparison with TRV and PRV. EFs were calculated from PRV by background-corrected end-diastolic and end-systolic frames. Volumes and EFs were calculated from TRV by region growing with different lower thresholds to search for the optimal threshold. EF from PRV correlated significantly with the real EF (r=0.94, P=0.00). The optimal threshold value for volume calculation from TRV in 336 cases was 50% (r=0.98, P=0.00) yielding the best slope after linear regression. When considering these calculated end-diastolic and end-systolic volumes, EF correlated well (r=0.99, P=0.00) with the real EF, and this correlation was significantly (P=0.04) higher than that of the EF from PRV. Our experiments prove that EF measured by TRV yields more accurate results compared with PRV in dynamic cardiac phantom studies.

Limitations of Doppler echocardiography for the post-operative evaluation of aortic coarctation.

Doppler blood flow measurements and derived pressure differences, through the Bernoulli equation, are used in the diagnosis of aortic coarctation, a congenital stenosis distal to the left subclavian artery. Doppler velocities remain elevated at the coarctation site after successful repair of coarctation, leading to high Doppler derived pressure differences without significant arm-leg pressure differences. We studied this apparent contradiction of two diagnostic methods, in vivo using patient and control data, and in vitro using a hydraulic model. Clinical and echocardiographic data from 31 patients, aged 13.0 +/- 4.0, 10.5 +/- 4.7 yr after coarctectomy by end-to-end anastomosis, and 18 age-matched healthy subjects were reviewed. Doppler peak velocities at the aortic isthmus were elevated in patients (2.2 +/- 0.4 vs. 1.2 +/- 0.2m/s, P < 0.001), corresponding to significant Doppler differences (20 +/- 7 mmHg), however, without significant arm-leg pressure differences. In all patients, a mild anatomic stenosis could still be observed. Local stiffness was increased. The hypothesis that the less distensible surgical scar in post-coarctectomy patients leads to a significant dynamic obstruction in systole was validated in a latex model of the aorta. Rigid rings (0.5-1.5 cm), matching the unloaded aortic diameter, were mounted around the aorta. Under loading conditions, Doppler peak velocities increased by 40 +/-7%, yielding Doppler differences of 21 +/- 3 mmHg, without a significant pressure drop. An alternative expression to calculate pressure differences, using both velocity and geometric information, was validated in the model. In conclusion, post-operatively, Doppler velocities remain elevated due to a mild anatomical and significant dynamic narrowing, but the specific geometry, resembling a tubular hypoplasia rather than an abrupt stenosis, permits an almost complete pressure recovery explaining the occurrence of Doppler differences in disagreement with the negligible arm-leg pressure difference.

Fixed region of nondistensibility after coarctation repair: in vitro validation of its influence on Doppler peak velocities.

After coarctectomy, local loss of distensibility is noted in addition to mild anatomic narrowing. We hypothesize that the increased Doppler peak velocities measured at the aortic isthmus in these patients partly reflect obstruction secondary to the stiff surgical scar. The hypothesis was studied in a pulsatile hydraulic model. Thirty-one patients (13.0 +/- 4.0 years of age), 10.5 +/- 4.7 years after coarctectomy by end-to-end anastomosis, were studied clinically and echocardiographically. Indexes of distensibility were calculated. The effect of isolated increased stiffness was studied in vitro with a stiff and a compliant 1:1 scale latex model of the aorta mounted in a pulsatile full-scale circulation loop. Local stiffening was obtained by a rigid ring mounted around the aorta, fitted to the dimension of the unloaded aorta. For different pressure and flow regimens, pressures and Doppler velocities were measured across the ring. Mean peak velocities at the surgical scar were 2.2 +/- 0.4 m/s. Mild anatomic stenosis was present. All distensibility indexes indicated locally increased stiffness (P <.001). In the stiff latex model, Doppler peak velocities increased from 1.89 +/- 0.04 m/s to 2.32 +/- 0.06 m/s (P <.03); in the compliant model, from 1.15 +/- 0.03 m/s to 1.79 +/- 0.05 m/s (P <.001). The increase of Doppler peak velocities depends on model compliance only and is independent of flow rate, length of the noncompliant segment, and viscosity of the perfusion fluid. Velocities do not change when semicircular stiffening is applied. We have demonstrated in vitro that isolated local nondistensibility leads to vessel narrowing during vascular distension. The relative contribution of local scar stiffness in the increase of Doppler peak velocities after coarctectomy was hereby assessed.

Assessment of the time constant of relaxation: insights from simulations and hemodynamic measurements.

The objective of this study was to use high-fidelity animal data and numerical simulations to gain more insight into the reliability of the estimated relaxation constant derived from left ventricular pressure decays, assuming a monoexponential model with either a fixed zero or free moving pressure asymptote. Comparison of the experimental data with the results of the simulations demonstrated a trade off between the fixed zero and the free moving asymptote approach. The latter method more closely fits the pressure curves and has the advantage of producing an extra coefficient with potential diagnostic information. On the other hand, this method suffers from larger standard errors on the estimated coefficients. The method with fixed zero asymptote produces values of the time constant of isovolumetric relaxation (tau) within a narrow confidence interval. However, if the pressure curve is actually decaying to a nonzero pressure asymptote, this method results in an inferior fit of the pressure curve and a biased estimation of tau.

Diastolic filling and pressure imaging: taking advantage of the information in a colour M-mode Doppler image.

The ability to derive non-invasively information on left ventricular diastolic function on one hand and pressure gradients on the other hand, makes Doppler ultrasound a very attractive tool in clinical practice. However, the limitations of the standard Doppler approaches in differentiating between normal and pseudonormal filling patterns, together with the limitations of the simplified Bernoulli equation for assessing pressure gradients, are well described. In this manuscript the role of colour M-mode Doppler echocardiography as a tool that can overcome these limitations is discussed. Relevant key concepts of the haemodynamics of left ventricular filling and its relationship with colour M-mode Doppler echocardiography are introduced.

Long-term follow-up after endoscopic sphincterotomy for bile duct stones in patients younger than 60 years of age.

BACKGROUND: Little is known about the long-term effects of endoscopic biliary sphincterotomy. METHODS: We retrospectively evaluated the rate of late complications after endoscopic sphincterotomy (EST) for bile duct stones. Patients had to meet the following inclusion criteria: (1) treated between 1976 and 1980, (2) complete stone removal after EST, (3) prior cholecystectomy or elective cholecystectomy within 2 months after EST, and (4) 60 years old or younger at the time of ERCP. A total of 100 patients were identified. Information was obtained from general practitioners and patients by telephone. Patients completed a postal questionnaire and a blood sample was obtained for liver function tests. RESULTS: Information was obtained for 94 patients (in the majority of cases [87%] from multiple sources). There were 26 men and 68 women with a mean age of 51 years at the time of ERCP (range, 23 to 60 years). Early complications (< 30 days) occurred in 14 patients (15%). One patient died of a retroperitoneal perforation secondary to EST. During a median period of 15 years (range, 3 to 18 years), 22 patients (24%) developed a total of 36 late complications. There were 21 patients with symptoms of recurrent bile duct stones and one patient with biliary pancreatitis. Other late complications, such as recurrent ascending cholangitis or malignant degeneration, were not observed. An ERCP was performed in 20 of the 22 patients with late complications and demonstrated bile duct stones in 13, combined with stenosis of the EST opening in 9 patients. Late complications were initially managed endoscopically and/or conservatively. One patient underwent surgery after failed endoscopic treatment and one patient died of cholangitis before she could undergo an ERCP. Twelve other patients died of unrelated causes during follow-up. CONCLUSIONS: After EST for bile duct stones, late complications occur in a significant proportion of patients. Stone recurrence remains the most important problem, but can in general be managed endoscopically.

Left ventricular function during transluminal angioplasty: a haemodynamic and angiographic study.

The response of left ventricular function, was studied in a series of patients undergoing percutaneous transluminal coronary angioplasty (PTCA). From 4 to 6 balloon inflations procedures per patient were performed with an average duration per occlusion of 51 +/- 12 sec (mean +/- SD), total occlusion time 252 +/- 140 sec. Analysis of left ventricular (LV) haemodynamics showed that the relaxation parameters peak negative rate of change in pressure and the early time constant of relaxation responded earliest to acute coronary occlusion while other parameters such as peak pressure, LV end-diastolic pressure, and peak positive rate of change of pressure responded more gradually and suggested a progressive depression in myocardial mechanics during the entire procedure. LV angiogram available in 14 patients indicate an early onset of asynchronous relaxation concurrent with the early response in peak -dP/dt and the time constant of early relaxation. All haemodynamic parameters fully recovered within minutes after the end of PTCA. The results of this study indicate no permanent dysfunction to global or regional myocardial mechanics, after PTCA with 4 to 6 coronary occlusions each lasting 40 to 60 seconds.

Effects of short-term administration of verapamil on left ventricular relaxation and filling dynamics measured by a combined hemodynamic-ultrasonic technique in patients with hypertrophic cardiomyopathy.

The effects of short-term administration of verapamil on left ventricular isovolumetric relaxation and early and late diastolic filling dynamics were studied in 10 patients with hypertrophic cardiomyopathy by a combined hemodynamic-ultrasonic technique. Left ventricular pressures (recorded with high-fidelity micromanometers) were determined simultaneously with M mode echocardiography. After 10 mg of verapamil was given intravenously (2 mg/min), left ventricular contractility and systolic pressure dropped significantly (p less than .05). Left ventricular dP/dt fell from 1947 +/- 544 to 1489 +/- 334 mm Hg/sec, maximal velocity of the contractile element at zero load fell from 50 +/- 17 to 42 +/- 15 1/sec, peak velocity contraction of the contractile element fell from 37 +/- 10 1/sec to 29 +/- 10 1/sec (p less than .05), and left ventricular systolic pressure fell from 149 +/- 30 to 127 +/- 22 mm Hg. Left ventricular negative dP/dt increased from 1770 +/- 479 to 1477 +/- 377 mm Hg/sec (p less than .05), and the time constant of isovolumetric pressure decay was prolonged from 48 +/- 9 to 64 +/- 15 msec (p less than .05). Left ventricular end-diastolic pressure rose from 21 +/- 7 to 23 +/- 6 mm Hg (p less than .05). The time constant of isovolumetric pressure decay was calculated in three different ways, but none of these measurements was influenced by verapamil. Time of isovolumetric relaxation, duration of rapid ventricular filling, and peak rate of left ventricular lengthening were not significantly influenced by verapamil and remained highly abnormal. In contrast, peak rate of left ventricular posterior wall thinning declined further after verapamil from 2.9 +/- 1.2 to 2.4 +/- 1.4 1/sec (p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)