Mechanization techniques for poplar development in Turkey

Annual commercial poplar wood production in Turkey is about 3.6 million cubic meters, half of which comes from hybrid poplar I-214. The poplar plantation areas of Turkey are 70% of the poplar plantation areas of the Near and Middle Eastern countries, and nearly 5% of the world. In this study, unit times of standard operations were investigated in poplar nurseries and plantations in which new mechanical technology was applied and compared with traditional methods. Analyses of unit times were made on 11 treatments for poplar nurseries and nine treatments for poplar plantations; some new methods are also recommended. Mechanization methods based on new technologies give promising results in poplar nurseries and plantations.     

Successful long‐term evaluation of intraocular titanium tacks for the mechanical stabilization of posterior segment ocular implants

Presently there are several lines of new intraocular implants under development (retina stimulators, drug delivery systems and others) that necessitate novel anchoring techniques for the posterior eye segment. It was the aim of this study to test intrasclerally inserted titanium tacks for this purpose in rabbit eyes under long‐term observation. Insertion of titanium tacks was performed through vitreous cavity and retina into the sclera in six rabbits after vitreous removal by mechanical and enzyme assisted (plasmin) vitrectomy. Follow‐up (between 2 weeks and 6 months, median: 4.5 months) and outcome were analyzed using fundus imaging, echography, electroretinography, light microscopy (standard, immunhistochemistry), and scanning electron microscopy. Intraoperative handling of tacks (Heimann design) revealed as a critical manouver due to relatively high mechanical force necessary for insertion. Position of tacks was stable without any signs of extrusion, tilting or dislocation in all eyes during the whole follow‐up period. Tack surface in contact with ocular tissue was embedded by a thin capsule of fibroglial avascular tissue extending from choroid and retina. Scanning electron microscopy of explanted tacks did not present any sign of surface degradation. The retina around inserted tacks presented a regional fibroglial transformation and thickening limited to the surround of insertion (radial diameter < 750 μm). No significant signs of proliferative disease or retinal degeneration were detected outside this area by funduscopy, histology, or in electroretinography. In one case the retina detached due to intraoperative complications not related to the insertion. Results of this study demonstrate that intrascleral tacks provide principially a permanent, stable, and biocompatible option for posterior segment anchoring necessary for the mechanical stabilization of intraocular implants. It is desired to design mimimalized structures in order to limit the surgical trauma of tack insertion.     

Analysis of bifurcations and stability properties of molecular systems

The dynamics and stability of a three-dimensional model of dissipative molecular systems are studied in detail The model considered is produced by an approximate quantum formulation, and it contains two parameters. It has been demonstrated analytically that the system exhibits 'cusp catastrophe' as in the case of potential systems; however, the non-potential nature of the dissipative model is reflected by the existence of limit cycles bifurcating from the equilibrium surface. The critical lines in the parameter plane and the family of limit cycles bifurcating from equilibria are determined analytically, and it has been shown that they are unstable     

Changes of Subjective Symptoms and Tear Film Biomarkers following Femto-LASIK

Femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) represents a common treatment modality in refractive surgery and shows excellent results in terms of safety, efficacy, predictability, and long-term stability. However, patients may be affected by dry eye symptoms. The aim of this study was to identify a potential association between subjective dry eye symptoms, objective dry eye markers, and possible changes in the tear film, which could be a target for future therapy development. Therefore, clinical (dry eye) examinations (OSDI, Schirmer test, lissamine green and fluorescein staining, BUT, visual acuity) were carried out before LASIK as well as 5 and 90 days post-OP. The dry eye marker MMP-9, cytokines (IL-1β, IL-8), and pain markers (NGF, CGRP) were quantified in tear samples with immunoassays. In addition, correlation analyses were performed. Clinical examinations revealed an upregulated OSDI score 5 days post-OP and an increased lissamine green staining score 90 days post-OP. Downregulated CGRP levels were noted 5 days post-OP, while other protein markers were not significantly altered after Femto-LASIK. Hence, Femto-LASIK surgery induced subjective symptoms like that of dry eye which could objectively rather be classified as Femto-LASIK-related discomfort. In the future, this could possibly be better detected and treated using pain markers such as CGRP.     

A comparative study on antibacterial activities of chitosan based products and their combinations with gentamicin against S. epidermidis and E. coli

Antibacterial activity of chitosan, and a graft copolymer based on chitosan namely chitosan-graft-poly(N-vinyl imidazole), (Chi-graft-PNVI), was studied against Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli). The graft copolymer was prepared by two different methods; via an N-protection route and without N-protection to observe the effect of free amine groups on the antibacterial activity. It was further investigated whether a combination of each of these products would produce a synergetic effect with the antibiotic gentamicin against S. epidermidis and E. coli compared to gentamicin alone. Antibacterial activity was determined by the inhibition zone measurement method. Results reveal an improvement in the antibacterial activity of gentamicin, when combined with chitosan or chitosan-based biomaterials against S. epidermidis and E. coli compared to that of gentamicin itself. When gentamicin is used in combination with Chi-graft-PNVI prepared via N-protection, antibacterial activity against S. epidermidis is three times higher in comparison with the activity of gentamicin alone according to the inhibition zone measurements. Gentamicin produces an inhibition zone of 8.2 ± 0.2 mm against S. epidermidis when undiluted, while the inhibition zone increases to 25.8 ± 0.7 mm in combination with Chi-graft-PNVI prepared via N-protection. These combinations have a potential to form a basis for new formulations of gentamicin with improved antibacterial activity and might allow usage of decreased doses of the antibiotic.     

Magnesium in the prophylaxis of migraine--a double-blind placebo-controlled study

The migraine prophylactic effect of 10 mmol magnesium twice-daily has been evaluated in a multicentre, prospective, randomized, double-blind, placebo-controlled study. Patients with two to six migraine attacks per month without aura, and history of migraine of at least 2 years, were included. A 4-week baseline period without medication was followed by 12 weeks of treatment with magnesium or placebo. The primary efficacy end-point was a reduction of at least 50% in intensity or duration of migraine attacks in hours at the end of the 12 weeks of treatment compared to baseline. With a calculated total sample size of 150 patients, an interim analysis was planned after completing treatment of at least 60 patients, which in fact was performed with 69 patients (64F, 5M), aged 18-64 years. Of these, 35 had received magnesium and 34 placebo. The number of responders was 10 in each group (28.6% under magnesium and 29.4% under placebo). As determined in the study protocol, this was a major reason to discontinue the trial. With regard to the number of migraine days or migraine attacks there was no benefit with magnesium compared to placebo. There were no centre-specific differences, and the final assessments of treatment efficacy by the doctor and patient were largely equivocal. With respect to tolerability and safety, 45.7% of patients in the magnesium group reported primarily mild adverse events like soft stool and diarrhoea in contrast to 23.5% in the placebo group.