Technological properties of Oenococcus oeni strains isolated from typical southern Italian wines.

AIMS: To isolate indigenous Oenococcus oeni strains suitable as starters for malolactic fermentation (MLF), using a reliable polyphasic approach. METHODS AND RESULTS: Oenococcus oeni strains were isolated from Nero di Troia wines undergoing spontaneous MLF. Samples were taken at the end of alcoholic fermentation and during MLF. Wine samples were diluted in a sterile physiological solution and plated on MRS and on modified FT80. Identification of O. oeni strains was performed by a polymerase chain reaction (PCR) experiment using strain-specific primers. Strains were further grouped using a multiplex RAPD-PCR analysis. Then, six strains were inoculated in two winelike media with two different ethanol concentrations (11 and 13% vol / vol) with a view to evaluate their capacity to grow and to perform MLF. In addition, a quantitative PCR (qRT-PCR) approach was adapted to monitor the physiological state of the strains selected. CONCLUSION: A positive correlation between the malolactic activity performance and the ability to develop and tolerate stress conditions was observed for two selected O. oeni strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The results reported are useful for the selection of indigenous MLF starter cultures with desired oenological traits from typical regional wines. It should be the base for the improvement in organoleptic quality of typical red wine.

Common gene expression in Medicago truncatula roots in response to Pseudomonas fluorescens colonization, mycorrhiza development and nodulation.

• Beneficial rhizosphere microorganisms may share similar molecular steps during root colonization. To test this hypothesis, we compared Medicago truncatula Gaertn. gene expression in roots colonized, or not colonized, by Glomus mosseae BEG12, Pseudomonas fluorescens C7R12 or Sinorhizobium meliloti 2011. • Pseudomonas fluorescens C7R12 formed colonies on the surface of M. truncatula roots and colonized root tissues intercellularly and intracellularly in a way similar to that previously described for other plants. • Semiquantitative reverse transcriptase polymerase chain reaction of a set of 12 mycorrhiza upregulated M. truncatula genes revealed different expression profiles in roots 3 weeks after inoculation with P. fluorescens or S. meliloti. Pseudomonas fluorescens colonization activated seven of the plant genes while nodulated root systems showed increased expression in only three genes and five appeared to be downregulated. • This first report of similar gene induction by a fluorescent pseudomonad and a mycorrhizal fungus in roots supports the hypothesis that some plant cell programmes may be shared during root colonization by these beneficial microorganisms. Less similarity existed in expression of the gene set with nodulation by S. meliloti.

Expression profiling of up-regulated plant and fungal genes in early and late stages of Medicago truncatula-Glomus mosseae interactions.

Suppression subtractive hybridization (SSH), expression profiling and EST sequencing identified 12 plant genes and six fungal genes that are expressed in the arbuscular mycorrhizal symbiosis between Medicago truncatula and Glomus mosseae. All the plant genes and three of the fungal genes were up-regulated in symbiotic tissues. Expression of 15 of the genes is described for the first time in mycorrhizal roots and two are novel sequences. Six M. truncatula genes were also activated during appressorium formation at the root surface, suggesting a role in this early stage of mycorrhiza establishment, whilst the other six plant genes were only induced in the late stages of mycorrhization and could be involved in the development or functioning of the symbiosis. Phosphate fertilization had no significant influence on expression of any of the plant genes. Expression profiling of G. mosseae genes indicated that two of them may be associated with appressorium development on roots and one with arbuscule formation or function. The other three fungal genes were expressed throughout the life-cycle of G. mosseae.

'Action substances' of peripheral nerve re-visited.

Fifty years ago, four 'action substances' were described as being 'liberated' from peripheral nerve in the course of activity. An attempt has been made to update this information. Confirmatory evidence is available that acetylcholine and thiamine do play a role in the course of activity. However, the question of the relationship in time between their release and the electrical events, and the possible effect on specific ionic gating mechanisms, remains unclarified. The 'liberation' of potassium has been found to be a transmembrane K efflux, and the question of the existence of another substance similar to thiamine has not been pursued.

High-frequency rotational ablation following failed percutaneous transluminal coronary angioplasty.

Percutaneous transluminal coronary angioplasty (PTCA) failed in 29 of 1,150 patients (2.5%) after successful passage of the guide wire. The reasons for failure were inability to pass the lesion with a balloon in 28 patients and inability to dilate the lesion in 1 patient. In these patients (15 stenoses and 14 chronic occlusions) rotational ablation was performed. We were able to pass the burr through the lesion in all of them, resulting in a reduction of diameter stenosis from 87 +/- 15 to 51 +/- 18%. Rotational ablation alone was initially successful (stenoses reduction > 20% and residual stenoses < 50%) in 15 of 29 (52%) patients. Additional PTCA was performed in 21 of 29 (72%) patients, in 8 to optimize the initially successful result and in 13 because the outcome was unsatisfactory. After dilatation the diameter stenosis was reduced to 41 +/- 14% immediately after the procedure and to 36 +/- 13% at 24 hr control. Overall success was achieved in 21 of 29 (72%) patients immediately after the procedure and in 26 of 29 (90%) patients at 24 hr control. No acute major complications occurred. We conclude that rotational ablation can be used as a safe and effective alternative when PTCA is not successful.

Magnetic stimulation of ferret papillary muscle.

1. Ferret papillary muscles were magnetically stimulated by the discharge of a capacitor through an inductance. 2. An induced current density of 39 mA cm-2 averaged over 280 microseconds (= 11 microC cm-2) corresponded to threshold. 3. A short galvanic current pulse was found to have a comparable charge threshold. 4. The time-varying magnetic field or the magnetically induced electrical field did not result in excitation unless current was allowed to flow. 5. Threshold conditions could be reached by adding subthreshold magnetically induced current to subthreshold galvanic current. A suprathreshold galvanic current could be prevented from exciting by simultaneously applying induced current of opposite direction. 6. It is concluded that outward current through the membrane capacity is the stimulus, independent of the origin of the current.

High frequency rotational ablation: an alternative in treating coronary artery stenoses and occlusions.

OBJECTIVE: To prove the safety and effectiveness of high frequency rotational ablation of coronary artery stenoses and occlusion in humans. SUBJECTS: 106 patients with symptoms (91 men, 15 women) who had 67 significant stenoses, mainly types B and C, and 46-chronic occlusions. MAIN OUTCOME MEASURES: Mean change in diameter stenosis after rotational angioplasty alone and in combination with percutaneous transluminal coronary angioplasty immediately after treatment and 24 hours and six months later; restenosis rates at six months; complication of treatment. RESULTS: Rotational ablation could not be used in five stenoses and 16 chronic occlusions because of inability to reach or cross the lesion with the Rotablator guide wire. In four cases rotational ablation failed. Initial angiographic and clinical success by rotational ablation was achieved in 40 of the 67 stenoses (60%) and in 18 of the 46 chronic occlusions (39%). Additional balloon angioplasty was performed in 45 patients, increasing the success rates to 79% and 54%, respectively. In the 62 stenoses treated by rotational ablation the angiographic diameter stenoses were reduced from 76% (SD 14%) to 32% (14%) after Rotablator treatment alone and from 75% (11%) to 33% (17%) with additional balloon angioplasty. In the 30 chronic occlusions treated by rotational ablation the angiographic diameter stenoses were reduced to 38% (18%). At six months angiographic restenosis was evident in nine of the 25 (36%) stenoses treated with rotational ablation alone, in seven of the 22 (32%) stenoses treated with rotational and balloon angioplasty, and in 14 of the 24 (58%) chronic occlusions. There were no procedural deaths and two patients (2%) underwent emergency coronary artery bypass grafting. Although no transmural infarction occurred, there were five (6%) non-Q wave infarctions (two embolic side branch occlusions, two subacute occlusions, and one acute occlusion). Clinically insignificant slight increases in creatine kinase activity were seen in five patients (6%). Severe coronary artery spasm unresponsive to medical treatment was provoked in seven cases (8%). CONCLUSIONS: High frequency rotational ablation is a safe and effective method for treating type B and C coronary artery lesions with results comparable to percutaneous transluminal coronary balloon angioplasty. The combined use of rotational ablation and balloon angioplasty is feasible and is necessary in about half of all procedures, in most cases because the lumen created by the biggest burr is too small.

Cardiac cellular electrophysiology: past and present.

The time-course of the cardiac action potential can be accounted for in terms of ionic currents crossing the cell membranes. Depolarizing current is carried by Na+ or Ca2+ entering the cells, repolarizing current by K+ leaving the cells. Membrane permeability for the passive movement of these ions is thought to be voltage-dependent as well as time-dependent. Net transfer of charge may also result from active transport, 2 Na+ out against 1 K+ in; or coupled exchange, 3 or 4 Na+ in against 1 Ca2+ out. This review follows the path by which present-day knowledge has been reached. It also gives a few examples to illustrate that electrophysiology has provided concepts useful to clinical cardiology.

Effects of palytoxin on the electrical activity of dog and rabbit heart.

Reversible effects of palytoxin, extracted from colonies of the soft coral Palythoa caribaeorum, are described. There is a decrease of both membrane resting potential and overshoot during activity. Rise time of the action potential is prolonged, while repolarization is shortened. The electrical events resemble those seen with metabolic poisons.

[Propagation of stimuli]. / Erregungsausbreitung

Cardiac muscle is considered as a biological cable, similar to fibres of skeletal muscle or nerve. "Local currents" within the core of the cable and through the extracellular space are responsible for the propagation of membrane excitation. Conduction velocity depends on (i) fibre diameter, (ii) specific resistance of the core and interstitial fluid, (iii) strength of possible inward current through the surface membrane. Conduction delay and possible block is found at sites of transition between terminal Purkinje fibres and ventricular muscle. Monophasic action potentials of somewhat different shapes are recorded from various parts of the heart. A slow upstroke is characteristic for sites of low conduction velocity (SA-node, AV-node). A progressive decrease of resting potential in the phase of diastole is typical for regions showing a tendency to automatic impulse generation (SA-node, AV-node, Purkinje fibres). Cardiac muscle is a functional syncytium. This statement is based on (i) measurements of electrical resistance between cells and (ii) diffusion experiments using tracer substances. Progressive de-coupling is observed under various pathological conditions, resulting in slow conduction or block.

Low resistance pathways between myocardial cells.

To test the hypothesis of whether the intercalated discs represent a low resistance to diffusing ions, a method was developed to study the longitudinal diffusion of radioactive potassium (42K), tetraethylammonium ([14C]TEA), and the fluorescent dye Procion yellow (PY) in sheep and calf heart bundles. The method involved 1) loading the cells, 2) allowing the ions to diffuse for periods of 2-6 hr, 3) freezing the bundle in liquid air and cutting it into equal slices of 0.5 mm, 4) measuring the concentration of the ion in each slice. From the results, the diffusion of coefficients were considered to be due partially to the discs and partially to the myoplasm. The permeabilities of the nexal membranes were 7.68-10(-3), 1.27-10(-3), and 1.4-10(-6) cm/sec for 42K, 14C-TEA, and PY. These values are 9,600, 21,000, and 220 times more than the corresponding ones for the surface membrane. The disc resistance for potassium, the main intracellular charge carrier, was about 0.9 ohm cm2. From the van der Waals sizes of the ions, the diameter of the nexal pores has to be 10-15 A. It is concluded that the junctions between myocardial cells have low resistances and that propagation of action potentials is possible by local circuit currents.

Membrane currents in mammalian ventricular heart muscle fibers using a voltage-clamp technique.

Bundles of sheep ventricular fibers were voltage-clamped utilizing a modified sucrose gap technique and intracellular voltage control. An action potential was fired off in the usual way, and the clamp circuit was switched on at preselected times during activity. Clamping the membrane back to its resting potential during the early part of an action potential resulted in a surge of inward current. The initial amplitude of this current surge decreased as the clamp was switched on progressively later during the action potential. Inward current decreasing as a function of time was also recorded if the membrane potential was clamped beyond the presumed K equilibrium potential (to -130 mv). Clamping the membrane to the inside positive range (+40 mv to +60 mv) at different times of an action potential resulted in a step of outward current which was not time-dependent. The results suggest that normal repolarization of sheep ventricle depends on a time-dependent decrease of inward current (Na, Ca) rather than on a time-dependent increase of outward current (K).

Electrical constants of trabecular muscle from mammalian heart.

1. The passive electrical properties of muscle bundles obtained from the right ventricle of sheep or calf hearts were determined. Preparations were kept in silicon oil; through extracellular electrodes constant current pulses were made to flow between the ends of the bundles.2. Using micro-electrodes for potential recording, the following data were obtained: (i) a space constant of 880 mu; (ii) a membrane time constant of 4.4 msec; (iii) a ratio of intra-to-extracellular longitudinal resistance of 3.5: 1; (iv) a conduction velocity of 0.75 m/sec.3. The intracellular specific resistance (R(i)) in the longitudinal direction was 470Omega cm, corresponding to 3 times R(i) of Purkinje fibres or 9 times the specific resistance of Tyrode solution.4. A calculation of specific membrane resistance (R(m)) and capacity (C(m)) was up against uncertainties in estimating the surface area. Taking morphological data as obtained by light microscopy, R(m) works out at 9100Omega cm(2), C(m) 0.81 muF/cm(2). Electron micrographs suggest that the true surface membrane might be either larger (T-tubules) or smaller (tight junctions between parallel fibres) than the surface area as seen by the light microscope.5. The apparently small value of C(m) seems to indicate that the flow of current between ;outside' and ;inside' is restricted to only a fraction of the fibre surface, while a considerable part of the contact area between parallel fibres is of the low-resistance type. This would provide for functional connexions not only at the level of intercalated disks, but also along parallel-running fibres.