Mechanism of ultrafast non-reactive deactivation of the retinal chromophore in non-polar solvents.

The photoisomerization of the all-trans protonated Schiff base of retinal (SBR+) in solution is highly inefficient. The present theoretical and experimental investigation aims at disclosing the mechanisms of ultrafast, non-reactive relaxation of SBR+ that lead to the drastic decrease in the isomerization yield in non-polar solvents. Our pump-probe measurements demonstrate the sensitivity of the all-trans SBR+ excited-state dynamics on the electrostatic interaction with the surrounding counterions and the crucial importance of the chromophore microenvironment. Our computational study focuses for the first time on the retinal chromophore-counterion pairs that are formed in non-polar solvents. By employing TDDFT-based nonadiabatic dynamics simulations and ADC(2) reaction paths calculations we found that internal conversion from the initially excited state to an inter-molecular charge transfer state with excitation localized on the counterion, leads to dissociation of the chromophore-counterion pair and to the abortion of isomerization. Barriers to conical intersection with the inter-molecular charge transfer state were found in the range 0.42-0.67 eV at the ADC(2) level. The existence of a barrier along the non-reactive relaxation pathways explains the observation that in solution the excitation on the blue edge of the SBR+ absorption leads to decrease in the isomerization yield with respect to the excitation at the red edge.

Kinematic magnetic resonance imaging study of the brain stem and cervical cord by dynamic neck motion.

BACKGROUND: The aim was to examine the position of the brain stem and cervical cord following the neck flexion and extension. MATERIALS AND METHODS: The serial sagittal T2-weighted magnetic resonance imaging (MRI) sections of the cervical cord and brain stem were made in 6 volunteers. The images were mainly used to measure certain distances and angles of the brain stem and cervical cord in the neutral position, and then following the head and neck flexion and extension. RESULTS: The measurements showed that the pons is slightly closer to the clivus following the neck flexion; the medulla oblongata is somewhat distant to the basion but closer to the odontoid process. At the same time, the spino-medullary angle diminishes in size. On the other hand, the upper cervical cord slightly approaches the posterior wall of the spinal canal, the lower cervical cord is closer to the anterior wall, while the angle between them is significantly larger in size. After the cervical cord extension, the rostral pons is somewhat distant to the clivus, whereas the caudal pons and the medulla are slightly closer to the clivus and the basion. At the same time, the spino-medullary angle diminishes in size. The cervical cord is mainly closer to the posterior wall of the spinal canal, whilst its angle is significantly smaller. CONCLUSIONS: The obtained results regarding the brain stem and cervical cord motion can be useful in the kinetic MRI examination of certain congenital disorders, degenerative diseases, and traumatic injuries of the craniovertebral junction and the cervical spine.

[Current trends in surgical treatment of radial nerve injuries associated with injuries of the humerus].

Radial nerve is the most common injured peripheral nerve after bone and wrist injuries in human body. Radial nerve can be injured by force causing fracture of the humeral shaft, due to compound fracture of the bone or by direct injury with small fragments of the bone. This happen in of cases and in remaining caseswas caused by manipulation during the treatment of the fracture of the humeral shaft. Because of the possibility of spontaneous recovery, indication and timing of surgical treatment of the radial nerve still remain controversial. There is contradictory approach in the treatment of the injured radial nerve. In a period betwen 1979 and 2005 year we have operated 193 patients with injury of radial nerve. Among them, 97 (50.2%) have had combined injury of the humeral shaft or proximal part of radius. Rest of injuries of the radial nerve were associated with manipulation during treatment. Surgical treatment has been performed in a period between three and four months after neurological deficit. Analysing our result regarding recovery of the motor function we have used combination of gradation including British Medical Council Score and modified Highet Scale to obtain satisfactory analysis of useful functional recovery of motor function after surgical procedure. We have classified results as bad M O-2 for all muscles innervated by the radial nerve; satisfactory M3, for extensors of the wrist and fingers and M O-2 for abductor of the thumb, good M 4-5 extensors of the wrist and fingers and M3 for abductor of the thumb, and excellent M 4-5 for all muscles.

[Carpal tunnel syndrome--surgical and anesthesiology considerations].

Carpal tunnel syndrome presents the most common peripheral nerve entrapment, and section of carpal transverse ligament is the most common procedure in peripheral nerve surgery. Favourable outcomes depend on several factors including correct diagnosis, careful patient selection, precise operative technique and appropriate postoperative care. The goal of this paper is to establish the most common causes of failed surgery analysing primary and secondary outcomes, and to give the possibility for better results in the future. Analysis was based on 250 operated patients. Primary outcome and secondary outcome 3 months after surgery was estimated. Total rate of complications was 8% with persistent complaints in 7 (35%) patients and recurrent symptoms in 13 (65%) patients.

[The position of anterior cuciate ligament in frontal and sagittal plane].

INTRODUCTION: Position of the anterior cruciate ligament (ACL) represents one of the anatomical factors which can lead to the rupture of the ligament. AIM: The aim of this study was to overview and compare gender and age differences of the position of the ACL and its relation with the medial aspect of the lateral femoral condyle. METHOD: The measurements were performed on the fifty cadaver knees (32 male and 18 female) aged between 15 - 53 years with intact ACL. We were measuring the angle of the ACL in sagittal and frontal plane and the angle of the medial aspect of the lateral condyle in frontal and horizontal plane. RESULTS: Measurements of the ACL in sagittal plane and measurements of the angle of the medial aspect of the lateral femoral condyle in horizontal plane showed statistically significant variations with the age (p < 0.05 and p < 0.01, respectively). The angle of the medial aspect of the lateral femoral condyle in frontal plane was statistically significant higher than the same measured angle in the horizontal plane ( p < 0.01). CONCLUSION: ACL fomis narrower angle with medial aspect of the lateral femoral condyle in extension of lower leg than in flexion as a result of smaller angle of the medial aspect of the lateral femoral condyle in frontal compared to horizontal plane.

Quantum mechanical study of secondary structure formation in protected dipeptides.

An extensive computational study of the conformational preferences of three capped dipeptides: Ac-Xxx-Phe-NH(2), Xxx = Gly, Ala, Val is reported. On the basis of local second-order Møller-Plesset perturbation theory (LMP2) and DFT computations we were able to identify the experimentally observed conformers as gamma(L)-gamma(L)(g-) and beta-turn I(g+) in Ac-Gly-Phe-NH(2), and Ac-Ala-Phe-NH(2), and as the closely related gamma(L)(g+)-gamma(L)(g-) and beta-turn I(a,g+) in Ac-Val-Phe-NH(2). In contrast to the experimental observation that peptides with bulky side chain have a propensity for beta-turns, we show that in Ac-Val-Phe-NH(2) the minimum energy structure corresponds to the experimentally non detected beta-strand.

A computational study of electronic and spectroscopic properties of formic acid dimer isotopologues.

We consider the effect of isotopic labeling on the electric charge distribution and dynamics of the formic acid dimer. Our investigation is based on accurate ab initio calculations of vibrationally induced dipole moments and multidimensional quantum calculations of vibrational ground-state splittings. It is found that non-negligible dipole moments of mu = 0.032 D and mu = 0.021 D arise in HCOOH-DOOCD and HCOOH-DOOCH, respectively, suggesting the feasibility of microwave studies. Within the reaction surface Hamiltonian approach a ratio of splittings of 1:0.2:0.045 is predicted for HCOOH-HOOCH:HCOOH-DOOCH:HCOOD-DOOCH.

[Reconstruction of the alae nasi by folded nasolabial flap].

Reconstruction of the nose is very old surgical procedure and, in fact, represents the beginnings of plastic surgery. In reconstruction, an effort has to be made in order to achieve a normal look. A surgeon must choose carefully the method of reconstruction, taking into consideration the skin color, texture and nasal topography. Full-thickness nasal defects in alar region are very difficult for reconstruction due to anatomic characteristics and structures, which are very important for normal breathing and cosmetic result. Our study analyzed 16 patients with full-thickness defect of alae nasi. Folded nasolabial flaps were used for reconstruction of these defects. Good results were achieved in all cases. The flap was vital. No flap necrosis was reported in any of these patients. The lining of the nose was good. Postoperatively, the alar edge was thickened, but it became thinned after six months. The incision in donor's region was well placed in the natural line of nasolabial fold. It was concluded that folded nasolabial flap was extremely good one-step procedure for reconstruction of full-thickness defects of alar region.

[The excision width in surgical treatment of basal cell carcinoma].

Basal cell carcinoma originates from pluripotent cells of basal layer of epiderm, external covering of hair follicles, sebaceous glands or other skin adnexa. It is characterized by local infiltrating and sometimes destructive growth. There are several types of basal cell carcinomas that may be manifested in over 12 clinical forms. Surgical treatment depends to a large extent on the histological type, localization and its clinical manifestation. The analysis included 250 patients of both gender and different age, operated for basal cell carcinoma. Clinical characteristics of basal cell carcinoma and the width of the excision were described. It was concluded that the width of the excision of basal cell cancer was in relation to histological type.

C-fiber activation exacerbates sleep-disordered breathing in rats.

We reported previously that activation of vagal feedback by protoveratrines or serotonin exacerbates sleep apnea in rats, but each of these agents activates multiple afferent fiber types. To elucidate the specific impact of C-fiber activity on sleep apnea, the present study utilized capsaicin (CAP), which stimulates C-fibers via the CAP receptor. Nine adult Sprague-Dawley rats were instrumented for chronic polysomnography and recorded for 6 hours on four occasions. Prior to each recording, the animals received an intraperitoneal injection of either saline (control), or CAP 0.1, 1.0, or 10.0 mg/kg. Respiration was monitored by single-chamber plethysmography and apneas were scored as breaths longer than 2.5 seconds not preceded by a sigh. CAP increased apneas during non-rapid eye movement (NREM) sleep (p < 0.05 vs control) and reduced respiratory minute ventilation by about 15% in all behavioral states (waking, NREM, and REM sleep). We conclude that selective pharmacological activation of C-fibers produces a diathesis of sleep-disordered breathing specific to NREM sleep in rats.

Capillary zone electrophoresis separation of tryptophan and its metabolites, including quinolinic acid.

Capillary zone electrophoresis with UV absorbance detection was used to separate tryptophan and ten of its metabolites. Run buffers of pH 4.0-10.0 were evaluated for their effect on resolution; a pH 9.6 buffer was found to give optimum separation of all components. Ethylenediaminetetraacetic acid (EDTA), which prevents complexation of some analytes with polyvalent cations, was included in the run buffer to insure good peak shape and reproducible mobilities. The resulting method was used to detect the presence of quinolinic acid in a urine sample.