New triazole-bearing gramine derivatives - synthesis, structural analysis and protective effect against oxidative haemolysis.

The new series of triazole-bearing gramine derivatives were synthesized through a CuAAC procedure. The structures of all newly obtained compounds were confirmed by spectroscopic analysis and DFT methods. The obtained derivatives were screened for their protective potency against oxidative haemolysis induced by free radicals generated from 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). Our work demonstrates that derivatives with propyl or octyl linker and phthalimide group associated with indole-triazole moiety, which have a folded structure, effectively protect human erythrocytes against oxidative stress-induced haemolysis.

The contractile properties of motor units in the rat flexor digitorum brevis muscle have continuous distribution.

The majority of motor unit studies were performed predominantly on calf muscles, where three types of units: S, FR and FF were found. These muscles are involved in postural activity, walking, running and jumping. The properties of foot muscles that perform other functions, e.g. scratching (in animals), and are purely co-active with calf muscles, are poorly known. The aim of the present study was to investigate the contractile properties of motor units in the flexor digitorum brevis. Fifty-six motor units were studied in male Wistar rats. Several methods of fast/slow motor unit categorization, presence of sag, contraction time values, and 20 Hz index, did not allow the separation of the studied motor units into discrete clusters. Therefore, motor units were divided into two groups: fatigable and resistant to fatigue, based on the fatigue index with the border value of 0.5 (although the distribution of the index was not bimodal). The fatigable motor units were stronger and faster compared to the resistant ones. In conclusion, the distribution of motor unit contractile properties in the studied foot muscle was continuous and indicated a lack of three separate physiological types of motor units that usually occurs for the majority of hindlimb muscles. This discrepancy appears to be associated with differences in the typical forms of motor unit activity in distinct muscles.

Model-generated decomposition of unfused tetani of motor units evoked by random stimulation.

Unfused tetani of motor units (MUs) evoked by stimulation at variable interpulse intervals at mean frequencies of 20, 25, 33, 40 and 50Hz were studied using ten functionally isolated fast-type MUs from the medial gastrocnemius muscle of adult Wistar rats. A previously proposed algorithm and computer program for mathematical decomposition of unfused tetani into a series of twitches, representing responses to individual pulses, were used. Analysis of the parameters of the decomposed twitches showed considerable variability in force of successive contractions. These twitches were extremely variable with up to 2-fold higher forces and longer contraction times than a single twitch evoked by one stimulus. However, when the stimulation frequency was decreased, the decomposed twitches became similar to the single twitch with respect to amplitude and contraction time. It was found that the basic contractile parameters of decomposed twitches could be predicted with high accuracy on the basis of the tetanus force level at which the next contraction begins. This analysis of the parameters of decomposed twitches demonstrated that the contractile responses of the muscle fibers to successive action potentials generated by motoneurons are highly variable and depend on the previous MU state.

Stability and enzymatic hydrolysis of quaternary ammonium-linked glucuronide metabolites of drugs with an aliphatic tertiary amine-implications for analysis.

Quaternary ammonium-linked glucuronide (N+-glucuronide) metabolites formed at aliphatic tertiary amine functional groups of xenobiotics have not been previously systematically studied with respect to their stability over a wide pH range and the ease of enzymatic hydrolysis by beta-glucuronidase from various sources. Three and four N+-glucuronide metabolites were respectively studied regarding their non-enzymatic and enzymatic stabilities where the metabolites were quantified by HPLC procedures. The N+-glucuronide metabolites of clozapine, cyclizine, and doxepin were stored at 18-22 degrees C in buffers at each nominal pH value over the 1-11 pH range. All three metabolites were stable for 3 months over the 4-10 pH range, while two metabolites slowly degraded (k in the range 0.002-0.01 days(-1)) at each of the other extreme pH values. In the initial enzymatic study the N+-glucuronide metabolites of chlorpromazine, clozapine, cyclizine, and doxepin were each treated in pH 5.0 and 7.4 buffers at 37 degrees C with beta-glucuronidase from three different sources, namely commercial brands from bovine liver, mollusks (Helix pomatia), and bacteria (Escherichia coli). Clozapine N+-glucuronide and the standard phenolphthalein O-glucuronide were susceptible to hydrolysis by the enzyme from all three sources. In contrast, the other three N+-glucuronide metabolites were resistant to hydrolysis, except for the E. coli source of beta-glucuronidase at pH 7.4. Also when examined at 50-fold increase in concentration of the enzyme sources from bovine liver and H. pomatia cyclizine N+-glucuronide was still resistant to hydrolysis by the former enzyme preparation. The optimum pH for the hydrolysis of each of the four N+-glucuronide metabolites from the E. coli enzyme source was investigated and was found to be in the pH range 6.5-7.4. These data have important implications with respect to the analysis of N+-glucuronide metabolites formed at an aliphatic tertiary amine: in general, their non-enzymatic stability will not be an important factor in the development of an analytical procedure, and when developing an indirect approach to the analysis of N+-glucuronide metabolites that involves beta-glucuronidase hydrolysis to the aglycone preliminary work should involve determining the appropriate enzyme source, buffer pH, and length of time of incubation.

Brain reorganization in patients with spinal cord compression evaluated using fMRI.

OBJECTIVE: This prospective study characterizes the reorganization that occurs within the primary sensorimotor cortices following decompression of cervical spinal stenosis. METHODS: Twelve right-handed patients with cervical myelopathy underwent blood oxygenation level dependent functional MRI (fMRI) prior to decompression and 6 months following surgery. Ten right-handed controls also underwent fMRI. All subjects performed a finger-tapping paradigm with the right hand. Volume time course data were corrected for temporal serial correlation and % normalized before inclusion in the general linear model. Activation maps were created for each group using a threshold of p < 0.005 with Bonferroni correction. Between-group differences in left hemisphere volume of activation (VOA) were measured along the precentral gyrus (PrCG) and postcentral gyrus (PoCG). Each subject also completed clinical questionnaires. RESULTS: Prior to surgery, patients demonstrated a larger VOA (1.23 cm(3), t(max) = 11.8) in comparison to controls within the PrCG. This difference increased following surgery (2.99 cm(3), t(max) = 13.6). Within the PoCG, controls demonstrated a larger VOA (0.53 cm(3), t(max) = 8.28) than preoperative patients. This difference decreased by 0.12 cm(3) (t(max) = 7.05) following surgery. Preoperatively, patients had a 21.7 cm(3) VOA (t(max) = 29.4) within the sensorimotor cortex with the center of gravity located within Brodmann area (BA) 3. Following surgery, the VOA increased to 23.1 cm(3) (t(max) = 26.1) within BA 3. There were significant improvements in clinical outcomes following surgery. CONCLUSIONS: Spinal cord compression resulted in an increase in volume of activation (VOA) within the precentral gyrus (PrCG) and a loss of VOA within the postcentral gyrus (PoCG) in comparison to controls. Surgical decompression results in cortical reorganization with enlarging VOA within both the PrCG and PoCG.