Does trans-spinal and local DC polarization affect presynaptic inhibition and post-activation depression?

KEY POINTS: Trans-spinal polarization was recently introduced as a means to improve deficient spinal functions. However, only a few attempts have been made to examine the mechanisms underlying DC actions. We have now examined the effects of DC on two spinal modulatory systems, presynaptic inhibition and post-activation depression, considering whether they might weaken exaggerated spinal reflexes and enhance excessively weakened ones. Direct current effects were evoked by using local intraspinal DC application (0.3-0.4 µA) in deeply anaesthetized rats and were compared with the effects of trans-spinal polarization (0.8-1.0 mA). Effects of local intraspinal DC were found to be polarity dependent, as locally applied cathodal polarization enhanced presynaptic inhibition and post-activation depression, whereas anodal polarization weakened them. In contrast, both cathodal and anodal trans-spinal polarization facilitated them. The results suggest some common DC-sensitive mechanisms of presynaptic inhibition and post-activation depression, because both were facilitated or depressed by DC in parallel. ABSTRACT: Direct current (DC) polarization has been demonstrated to alleviate the effects of various deficits in the operation of the central nervous system. However, the effects of trans-spinal DC stimulation (tsDCS) have been investigated less extensively than the effects of transcranial DC stimulation, and their cellular mechanisms have not been elucidated. The main objectives of this study were, therefore, to extend our previous analysis of DC effects on the excitability of primary afferents and synaptic transmission by examining the effects of DC on two spinal modulatory feedback systems, presynaptic inhibition and post-activation depression, in an anaesthetized rat preparation. Other objectives were to compare the effects of locally and trans-spinally applied DC (locDC and tsDCS). Local polarization at the sites of terminal branching of afferent fibres was found to induce polarity-dependent actions on presynaptic inhibition and post-activation depression, as cathodal locDC enhanced them and anodal locDC depressed them. In contrast, tsDCS modulated presynaptic inhibition and post-activation depression in a polarity-independent fashion because both cathodal and anodal tsDCS facilitated them. The results show that the local presynaptic actions of DC might counteract both excessively strong and excessively weak monosynaptic actions of group Ia and cutaneous afferents. However, they indicate that trans-spinally applied DC might counteract the exaggerated spinal reflexes but have an adverse effect on pathologically weakened spinal activity by additional presynaptic weakening. The results are also relevant for the analysis of the basic properties of presynaptic inhibition and post-activation depression because they indicate that some common DC-sensitive mechanisms contribute to them.

Long-term effects of whole-body vibration on motor unit contractile function and myosin heavy chain composition in the rat medial gastrocnemius.

Structural and physiological mechanisms underling functional adaptations of a muscle to chronic whole-body vibration (WBV) are poorly understood. The study aimed at examining the contractile properties of motor units and the myosin heavy chain (MHC) expression in rat medial gastrocnemius muscle in response to 3- or 6-month periods of the WBV. The three-month WBV induced modifications of contractile properties principally in slow (S) and fast resistant to fatigue (FR) motor units. In S units an increase in the maximum tetanus force, a reduction in the twitch force and a decrease in the twitch-to-tetanus force ratio were found. In FR units a shortening in the twitch time parameters, a decrease in the twitch-to-tetanus ratio and an increase in the fatigue resistance were observed. In addition, a decrease in the type I and an increase in the type IIax MHC content were revealed. The six-month WBV caused a decrease in the twitch-to-tetanus force ratio in S and FR units. Other structural and physiological changes in MU properties previously seen were no longer apparent. In conclusion, responses to the long-term WBV stimulus vary between particular types of motor units, what suggests that multiple adaptive processes in muscle tissue are involved.

Gasochromic switching of Ta and Pd-doped nanocrystalline TiO2 thin films.

In this work TiO2:(Ta, Pd) thin films with gasochromic properties have been described. Thin films were prepared by reactive magnetron sputtering process using mosaic Ti-Ta-Pd target. The amounts of dopants were 2.54 at.% and 12.36 at.% of Ta and Pd, respectively. The results of optical measurements performed at presence of ethanol and additional heating of the sample up to 350 degrees C have shown an abrupt change of transmission level from 80% down to 10% in VIS and in IR range. The gasochromic change was very fast. Moreover, rapid cooling (down to room temperature) in an air ambient results in stable thin film coloration. The reverse effect (bleaching) was obtained after annealing at 500 degrees C in an ambient air.

New theory of acoustic signal detection in the inner ear - An explanation of bifilar structure of the cochlea.

In this work a new theory of acoustic signal detection in the inner ear and an experimental explanation of the causes of bifilar cochlear structure was presented. Our innovative approach describes sound detection in a completely different way from the one currently adopted. It requires analyzing the inner ear system in the form of a bent spiral and assuming that perilymph in such a small system behaves like a non-Newtonian fluid. The necessity of analyzing the system in the form of a bifilar spiral results from the need to compensate the head movements, so far omitted in the analysis. We suggest that the construction and the role of the oval window and the stapes are different than just a simple piston that converts mechanical signals to hydrokinetic ones. Stapes provides uniform distribution of the hydrokinetic signal in the spiral cochlear system, and the conversion of momentum to angular momentum creates a force perpendicular to the vestibular membrane, which causes the effect of its deflection, what has not yet been explained.

A pressurized flow reactor combustion experiment interfaced with synchrotron double imaging photoelectron photoion coincidence spectroscopy.

A new pressurized low-temperature combustion experiment has been commissioned at the Swiss Light Source, Paul Scherrer Institute. The experiment uses photoionization with tunable synchrotron radiation and double imaging photoelectron photoion coincidence (i2PEPICO) detection at the vacuum ultraviolet beamline. The experimental setup is described, including the high-pressure reactor experiment, sampling interface, and reactant delivery system. The CRF-PEPICO (Combustion Reactions Followed by Photoelectron Photoion Coincidence) endstation and VUV beamline are briefly elaborated. The novel aspects of the apparatus and the new components are elucidated in detail, such as the fluid supply system to the reactor and the reactor integration into the endstation. We also present a system overview of the experimental setup. The technical details are followed by a description of the experimental procedure used to operate the pressurized flow reactor setup. Finally, first experimental results demonstrating the capability of the setup are provided and analyzed. A major advantage of this new experiment is that the excellent isomer resolution capabilities of the i2PEPICO technique can be transferred to the investigation of reactions at elevated pressures of several bars. This enables the investigation of pressure effects on the reactivity of fuel mixtures and covers more realistic conditions found in technical combustors. The capability to obtain quantitative oxidation data is confirmed, and the main and certain intermediate species are quantified for a selected condition. The results show excellent agreement with a chemical kinetics model and previously published reference measurements performed with a gas chromatography setup.

Dye chromoendoscopy leads to a higher adenoma detection in the duodenum and stomach in patients with familial adenomatous polyposis.

Backround and study aims Duodenal cancer is the cancer most often seen in patients with familial adenomatous polyposis (FAP) who have undergone risk-reducing colonic surgery. Almost all patients with FAP eventually develop duodenal adenomas and risk for duodenal cancer is up to 12 % with poor prognosis. In addition, there is a rising concern regarding increased gastric cancer risk in patients with FAP. Our aim was to enhance polyp detection by using CE (CE) with the application of indigo carmine dye. Patient and methods We conducted a prospective, blinded study of patients with FAP undergoing endoscopic examination of the upper gastrointestinal tract. First, a standard white-light examination (WLE) was done followed by an examination performed by an endoscopist who was blinded to the previous examination, using chromoendoscopy (CE) (0.4 % indigo carmine dye). Results Fifty patients were included in the study. Using WLE, a median number of 13 adenomas (range 0-90) was detected compared to 23 adenomas/patient (range 0-150; P  < 0.0001) detected after staining, leading to a higher Spigelman stage in 16 patients (32 %; P  = 0.0003). CE detected significantly more larger adenomas (> 10 mm) than WLE (12 vs. 19; P  = 0.0391). In the gastric antral region, a median number of 0 adenomas (range 0-6) before and 0.5 adenomas (range 0-7) after staining ( P  = 0.0025) were detected. Conclusion This prospective endoscopic trial, to our knowledge the largest in patients with FAP, showed a significant impact of CE on adenoma detection and therapeutic management in the upper gastrointestinal tract. This leads to more intensive surveillance intervals.

Cryosurgery for resectable and unresectable hepatic metastases from colorectal cancer.

AIMS: Hepatic cryosurgery is useful for patients with hepatic metastases from colorectal cancer confined to the liver but considered unresectables because of the number and location of lesions. While encouraging results were reported following cryosurgery for unresectable liver metastases we considered particularly valuable to examine the safety and effectiveness of cryosurgery in patients with resectable and unresectable metastases from colorectal cancer. METHODS: Between January 1997 and September 2005, 53 patients with liver metastases from colorectal cancer underwent hepatic cryosurgery at our institution. Hepatic metastases were resectable in 31 (58.5%) patients and unresectable in 22 (41.5%). RESULTS: A total of 136 liver metastases were treated in 53 patients. The size of treated lesions ranged from 0.5 to 10 cm (mean 2.7). There were 2 postoperative deaths (3.8%) from massive bleeding and from cryoshock. The overall morbidity rate was 66%. The median follow-up was 24.8 months. The overall survival rate at 12 months was 86.1%, at 48 months it was 27%. No significant difference was found between survival rates in patients with resectable or unresectable metastases. Among 31 patients with resectable liver metastases 7 (22.6%) patients developed recurrence at the site of cryosurgery. CONCLUSION: Survival rates were comparables between patients with resectable and unresectable metastases but a high complication rate and a substantial rate of local recurrence following cryosurgery should caution against its use to treat resectable disease.

Influence of the surface properties on bactericidal and fungicidal activity of magnetron sputtered Ti-Ag and Nb-Ag thin films.

In this study the comparative investigations of structural, surface and bactericidal properties of Ti-Ag and Nb-Ag thin films have been carried out. Ti-Ag and Nb-Ag coatings were deposited on silicon and fused silica substrates by magnetron co-sputtering method using innovative multi-target apparatus. The physicochemical properties of prepared thin films were examined with the aid of X-ray diffraction, grazing incidence X-ray diffraction, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy methods. Moreover, the wettability of the surface was determined. It was found that both, Ti-Ag and Nb-Ag thin films were nanocrystalline. In the case of Ag-Ti film presence of AgTi3 and Ag phases was identified, while in the structure of Nb-Ag only silver occurred in a crystal form. In both cases the average size of crystallites was ca. 11 nm. Moreover, according to scanning electron microscopy and atomic force microscopy investigations the surface of Nb-Ag thin films was covered with Ag-agglomerates, while Ti-Ag surface was smooth and devoid of silver particles. Studies of biological activity of deposited coatings in contact with Bacillus subtilis, Pseudomonas aeruginosa, Enterococcus hirae, Klebisiella pneumoniae, Escherichia coli, Staphylococcus aureus and Candida albicans were performed. It was found that prepared coatings were bactericidal and fungicidal even in a short term-contact, i.e. after 2 h.

Determination of structural, mechanical and corrosion properties of Nb2O5 and (NbyCu 1-y)Ox thin films deposited on Ti6Al4V alloy substrates for dental implant applications.

In this paper comparative studies on the structural, mechanical and corrosion properties of Nb2O5/Ti and (NbyCu1-y)Ox/Ti alloy systems have been investigated. Pure layers of niobia and niobia with a copper addition were deposited on a Ti6Al4V titanium alloy surface using the magnetron sputtering method. The physicochemical properties of the prepared thin films were examined with the aid of XRD, XPS SEM and AFM measurements. The mechanical properties (i.e., nanohardness, Young's modulus and abrasion resistance) were performed using nanoindentation and a steel wool test. The corrosion properties of the coatings were determined by analysis of the voltammetric curves. The deposited coatings were crack free, exhibited good adherence to the substrate, no discontinuity of the thin film was observed and the surface morphology was homogeneous. The hardness of pure niobium pentoxide was ca. 8.64GPa. The obtained results showed that the addition of copper into pure niobia resulted in the preparation of a layer with a lower hardness of ca. 7.79 GPa (for niobia with 17 at.% Cu) and 7.75 GPa (for niobia with 25 at.% Cu). The corrosion properties of the tested thin films deposited on the surface of titanium alloy depended on the composition of the thin layer. The addition of copper (i.e. a noble metal) to Nb2O5 film increased the corrosion resistance followed by a significant decrease in the value of corrosion currents and, in case of the highest Cu content, the shift of corrosion potential towards the noble direction. The best corrosion properties were obtained from a sample of Ti6Al4V coated with (Nb0.75Cu0.25)Ox thin film. It seems that the tested materials could be used in the future as protection coatings for Ti alloys in biomedical applications such as implants.

[Port-site metastasis after laparoscopic resction of a duodenal stromal tumor]. / Métastase sur orifice de trocart après exérèse laparoscopique d'une tumeur stromale du duodénum.

Gastro-intestinal stromal tumors are rare and their evolution is dubious. This observation of port site metastasis after laparoscopic resection of a small duodenal stromal tumor would be, to our knowledge, the first case reported in the literature. Several direct and indirect mechanisms were supposed to be involved in the appearance of metastases after laparoscopic surgery, but the risk of dissemination remains badly evaluated on its frequency as well as on its mechanisms.

[Management of traumatic retroperitoneal hematoma]. / Conduite à tenir devant un hématome rétro-péritonéal d'origine traumatique.

Traumatic retroperitoneal hematoma (RPH) may arise from injury to bony structures, major blood vessels, and intestinal or retroperitoneal viscera. To categorize the management of RPH, the retroperitoneum may be divided into three zones. Zone 1 (central) extends from the esophageal hiatus to the sacral promontory. Zone 2 (lateral) extends from the lateral diaphragm to the iliac crest. Zone 3 (pelvic) is confined to the retroperitoneal space of the pelvic bowl. For the traumatized patient with RPH, laparotomy is mandated by persistent hemodynamic instability despite intensive volume replacement. The judgment of whether and when to explore the retroperitoneal hematoma is guided by the mechanism of injury (blunt or penetrating) and the location of the RPH. RPH localized to the upper central area (Zone 1) after penetrating trauma implies injury to the great vessels and always requires urgent surgical exploration. RPH in other zones should be evaluated by CT and/or angiography; ongoing hemorrhage may respond to therapeutic embolization.

[Usefulness of determining the conduction of sensory nerve fibers in the diagnosis of vibration disease]. / Przydatnosc oznaczania przewodzenia wlókien nerwowych czuciowych dla diagnostyki choroby wibracyjnej.

Thirty two metallurgical industry workers exposed to vibration (I group) and nine workers of the same industrial plant but unexposed to vibration (II group) underwent the following tests: electromyography--abductor dig. V, and abductor pollicis brevis, conductability of sensory fibers n. medianus and ulnaris, conductability of motoric fibers of n. ulnaris. In the third, control, group twenty five men had conductability norms determined. The results have been statistically analysed. Electromyography appeared more useful for the diagnosis of early symptoms of the vibration disease than for nerves conductability tests. The tests of sensory nerves conductability exhibit frequent deviations in the II group workers. Positive correlation was found between electromyography and nerves conductability findings.

Low-volume whole-body vibration lasting 3 or 6 months does not affect biomarkers in blood serum of rats.

Whole-body vibration training (WBV) has been reported to improve both, bone strength and neuromuscular performance. Although changes in hormonal and immunological parameters following vibration exercises were reported, there are still few studies concerning the immune response with respect to different duration of WBV. In our study, we aimed to establish whether three and six months of specific, short-lasting WBV (four bouts lasting 30 s, 1 min rest intervals) influences blood cell counts as well as some immunological parameters in rats. Adult male Wistar rats were assigned randomly to two groups trained for three (WBV3mo) or six (WBV6mo) months and results were compared to the age matched control group (C). After the training period, red and white blood cells, lymphocytes, monocytes, granulocytes, hemoglobin, and hematocrit, as well as interleukin-1b, interleukin-10, interleukin-6, and vascular endothelial growth factor levels were determined. No significant differences between WBV3mo, WBV6mo, and C groups in complete blood counts or in immunological parameters were found, indicating that the whole-body vibration training used in this study did not disturb the balance of examined indices, directly or indirectly involved in inflammatory processes.

You're fired! What to do, how to cope, finding a new job.

If you find yourself out of a job, do not despair. It has happened to the best and the brightest; you are not alone. If you have never lost a job consider yourself fortunate, but do not become complacent. It very well could happen to you sometime soon. Be prepared. Watch for the signs. And if it happens, remain the professional you have always been. There is always another, and probably better, job awaiting you.

The actions of lovastatin on platelet function and platelet eicosanoid receptors in type II hypercholesterolaemia. A double-blind, placebo-controlled, prospective study.

We have studied the effects of 12 weeks of lovastatin (20 mg per day) on platelet function and thromboxane formation in 18 patients with type II hypercholesterolaemia in a double-blind, placebo-controlled, prospective study. Lovastatin significantly reduced total serum and LDL-cholesterol by 20% and 25% respectively. Washed platelets of lovastatin-treated patients had significantly reduced collagen-induced aggregation and thromboxane formation ex vivo. There was no change in ADP-induced platelet aggregation, but a significant increase in prostacyclin (iloprost)-stimulated platelet cyclic AMP concentrations in lovastatin-treated patients. This was associated with a significant increase in the number of prostacyclin receptors in platelet membranes prepared from lovastatin-treated patients. There was also an increase in platelet thromboxane receptors. There were no such changes in the placebo group. These data confirm our original observation of normalization of platelet function in hypercholesterolaemia by HMGCoA reductase inhibitors and suggest changes in platelet membrane composition at the megakaryocyte level as a possible site of action.