Pillared Graphene Structures Supported by Vertically Aligned Carbon Nanotubes as the Potential Recognition Element for DNA Biosensors

The development of electrochemical biosensors is an important challenge in modern biomedicine since they allow detecting femto- and pico-molar concentrations of molecules. During this study, pillared graphene structures supported by vertically aligned carbon nanotubes (VACNT-graphene) are examined as the potential recognition element of DNA biosensors. Using mathematical modeling methods, the atomic supercells of different (VACNT-graphene) configurations and the energy profiles of its growth are found. Regarding the VACNT(12,6)-graphene doped with DNA nitrogenous bases, calculated band structure and conductivity parameters are used. The obtained results show the presence of adenine, cytosine, thymine, and guanine on the surface of VACNT(12,6)-graphene significantly changes its conductivity so the considered object could be the prospective element for DNA biosensing.     

Inhalant use in adolescents in northern Russia

Purpose

To determine the prevalence of inhalant use in Russian adolescents and to investigate associated psychosocial problems from a gender perspective.

Methods

Data on inhalant use and comorbid psychopathology were collected by means of self-reports from 2892 (42.4% boys) sixth to tenth grade students in public schools in Arkhangelsk, Russia. Multivariate analysis of covariance was used to assess differences in the levels of internalizing and externalizing problems in boys and girls, who were non-users and users of inhalants.

Results

The prevalence of inhalant use was 6.1% among boys and 3.4% among girls. Compared with non-users, inhalant users scored significantly higher on internalizing and externalizing problems, functional impairment and lower on academic motivation, with psychopathology increasing with age. While there were no gender differences for internalizing problems, increased levels of externalizing problems in inhalant users were gender-specific (significantly higher in boys).

Conclusions

Inhalant use is related to significantly higher levels of comorbid psychopathology in Russian adolescents. Comprehensive, evidence-based prevention and intervention policies are needed to address inhalant use and its harmful effects.

     

The cause of a depressed glomerular filtration rate after an ischaemic insult: whole kidney and superficial nephron study in the dog

Twenty-four hours after 90 min clamping of the left renal artery in dogs, the glomerular filtration rate (GFR) was decreased in the whole kidney (0.34 ml.min^–1g KW^–1 [KW=Kidney weight] vs 0.64 in contralateral unclamped kidney) just as in the single nephron (SNGFR, 19.7 vs 51.8 nl.min^–1). Renal blood flow (RBF) did not change; single nephron glomerular blood flow (SNGBF) was decreased by 9% only. After injection of Lissamine green into the renal artery, brief diffuse tinting of the whole kidney surface was observed. Thereafter, patchy coloration — corresponding to passage of the dye through patent tubuli — took place in approximately one-quarter to one-third of the kidney surface. Micropuncture measurements were carried out in these areas.The values of hydraulic pressure in peritubular capillaries and proximal convolutions were not different from those found in controls; directly measured glomerular capillary pressure was decreased (48.7 vs 59.5 mmHg). The ultrafiltration coefficient(K _f) was significantly depressed (2.7 vs 3.8 mmHg.nl^–1.min). Total kidney and arteriolar resistances remained unchanged but afferent resistance (R _A) was elevated (11%) and efferent resistance (R _E) was lowered (23%) compared with those of controls. Ninetyseven percent of proximally microinjected ³H-inulin was recovered from the control kidney but only 85 % from the kidney rendered ischaemic. In conclusion, the typical findings at 24 h after 90 min ischaemia are low GFR and SNGFR with normal RBF and almost normal superficial SNGBF values. This phenomenon is mainly due to a decrease in K _f and a decrease in R _E with a simultaneous increase in R _A; back-leak through damaged tubuli seems to play only a minor role.     

DYNC1H1 gene methylation correlates with severity of spinal muscular atrophy

Methylation profiles of CpG islands within the SLC23A2, CDK2AP1, and DYNC1H1 genes and their association with spinal muscular atrophy (SMA) severity were studied. High clinical heterogeneity of SMA suggests the existence of different factors modifying SMA phenotype with gene methylation as a plausible one. The genes picked up in our earlier genome‐wide methylation studies of SMA patients demonstrated obvious differences in their methylation patterns, thus suggesting the likely involvement of their protein products in SMA development. Significantly decreased methylation of CpG islands within exon 37 of the DYNC1H1 gene was observed in patients with a severe SMA manifestation (type I) compared to mildly affected SMA patients (types III–IV). This finding provides new information on peculiarities of methylation in clinically different types of SMA patients and gives a clue for identification of new SMA modifiers.     

Mammalian complex III heme dynamics studied with pump-probe spectroscopy and red light illuminations

The electronic or molecular mechanisms that initiate photobiomodulation (PBM) in cells are not yet fully understood. The porcine complex III (C-III) of the electron transport chain was characterized with transient absorption spectroscopy (TAS). We then applied our recently developed continuous wave laser coupled TAS procedure (CW-TAS) to investigate the effect of red light irradiances on the heme dynamics of C-III in its c₁ reduced state. The time constants were found to be 3.3 ± 0.3 ps for vibrational cooling of the oxidized state and 4.9 ± 0.4 ps for rebinding of the photodissociated axial ligand of the c₁ reduced state. The analysis of the CW-TAS procedure yielded no significant changes in the C-III heme dynamics. We rule out the possibility of 635 nm CW light at 4.7 mW/cm² inducing a PBM effect on the heme dynamic of C-III, specifically with the photodissociation of its axial ligand.     

Experimental and Numerical Investigations on High Performance SFRC: Cyclic Tensile Loading and Fatigue

In the present study, the capability of high-strength short steel fibers to control the degradation in high-performance concrete was experimentally examined and numerically simulated. To this end, notched prismatic high-performance concrete specimens with (HPSFRC) and without (HPC) short steel fibers were subjected to static and cyclic tensile tests up to 100,000 cycles. The cyclic tests showed that the rate of strain increase was lower for HPSFRC specimens and that the strain stagnated after around 10,000 cycles, which was not the case with HPC specimens. The microscopic examinations showed that in HPSFRC, a larger number of microcracks developed, but they had a smaller total surface area than the microcracks in the HPC. To further investigate the influence of fibers on the behavior of HPSFRC in the cracked state, displacement-controlled crack opening tests, as well as numerical simulations thereof, were carried out. Experiments have shown, and the numerical simulations have confirmed, that the inclusion of short steel fibers did not significantly affect the ultimate strength; however, it notably increased the post-cracking ductility of the material. Finally, the unloading/reloading behavior was examined, and it was observed that the unloading stiffness was stable even for significant crack openings; however, the hysteresis loops due to unloading/reloading were very small.     

Alcohol use in adolescents from northern Russia: the role of the social context

Drinking alcohol is an essential and commonplace part of life in Russia. Alcohol-related problems in the general population and among adolescents in particular has become a major public health concern. The problem cannot be solely explained by the frequency and quantity of alcohol consumption. The social determinants of drinking alcohol also need to be considered. These are the focus of the present investigation. The social determinants of drinking behaviour were assessed by self-reports (Social Context of Drinking Scale, Adolescent Alcohol Involvement Scale and Rutgers Alcohol Problem Index) in 387 secondary school students in Arkhangelsk, Russia. The factor structure for the Social Context of Drinking Scale was similar to that noted in respect of the original study [Thombs and Beck (1994) Health Education and Research 9, 13-22]. Significant gender differences in problem drinking and the social contexts of drinking were found. High intensity girl drinkers were likely to drink in most social contexts, whereas high intensity drinking boys were more likely to drink in the context of Stress Control. Furthermore, boy problem drinkers were more likely to drink in the context of School Defiance and Peer Acceptance, whereas girl problem drinkers tended to drink in the contexts of School Defiance and Stress Control. In general, the Social Context of Drinking Scale demonstrated a good ability to discriminate high from low intensity drinkers, and high from low problem drinkers. These results may provide useful information for targeted prevention programmes for adolescents.     

Impact of UVR-A on whole human lenses, supernatants of buffered human lens homogenates, and purified argpyrimidine and 3-OH-kynurenine

PURPOSE: Yellow chromophores and fluorescent compounds accumulate in the lens with age. Some of these compounds are photochemically active. The present study aimed to examine the photochemical effect of ultraviolet radiation-A (UVR-A) on the human lens. METHODS: Intact human lenses and supernatants of buffered lens homogenates were exposed to UVR-A. The effect of UVR-A was evaluated by time-resolved and steady-state fluorescence spectroscopy, visual evaluation of colour and protein gel electrophoresis. RESULTS: Intact lenses exposed to UVR-A showed no changes in time-resolved or steady-state fluorescence properties but the yellow coloration was visibly attenuated. The supernatants of buffered lens homogenates exposed to UVR-A demonstrated a reduction in time-resolved and steady-state fluorescent properties and protein cross-linking. CONCLUSIONS: Exposure of the intact lens to UVR-A causes chromophore bleaching without affecting fluorescence, indicating that non-fluorescent chromophores have been destroyed. After homogenization, both chromophores and fluorophores from the lens suffer damage and proteins aggregate. This indicates that powerful mechanisms of protection against UVR-A found in the intact lens are disturbed by homogenization of the lens, suggesting that isolated lens proteins cannot be used as a model system for studying cataractogenesis. Hypothetically, the protective mechanism could be related to the rigidly packed three-dimensional structure of the lens proteins or to the abundance of antioxidative and free radical scavenging defence systems.     

Artificial iris-lens diaphragm in reconstructive surgery for aniridia and aphakia

PURPOSE: To determine the efficacy and safety of surgical implantation of artificial iris-lens diaphragm in patients with anatomic or functional iris deficiencies, aphakia or cataract. SETTING: Svyatoslav Fyodorov MNTK Eye Microsurgery, Cheboksary, Russia. METHODS: Twenty eyes of 19 consecutive patients with combined iris and lens pathology of traumatic or congenital etiology were identified for an interventional noncomparative case series. The newly proposed model of an elastic iris-lens diaphragm with a colored haptic and additional support elements was implanted using various fixation approaches. RESULTS: Fifteen eyes (75%) experienced improvement in corrected visual acuities. The best spectacle-corrected visual acuity (BSCVA) in 2 eyes did not change, while the uncorrected visual acuity (UCVA) in these eyes increased. There were 3 eyes in which BSCVA deteriorated with no change or even slight improvement in UCVA. All patients were satisfied with the cosmetic results of the surgery and reported a decrease in glare and photophobia. There was 1 intraoperative complication of vitreous hemorrhage. Postoperatively, 2 cases of hyphema, 1 case of ciliochoroidal detachment, 4 eyes with exaggerated immediate postoperative reaction, and 1 eye with persistent low-grade cyclitis were observed. In 1 eye, there was persistent intraocular pressure rise. One eye showed signs of cystoid macular edema. No iris-lens diaphragm decentrations and no new or extensions of old retinal detachments were seen during the follow-up period. CONCLUSIONS: Artificial iris-lens diaphragm implantation effectively improved postoperative outcomes by correcting aphakia, reducing glare disability, and addressing cosmetic issues faced by iris-deficient, and aphakic or cataract patients. Although the iris-lens diaphragm appears to be safe, long-term results must be clarified in studies with longer follow-up and a larger patient population.