POTENTIAL USE OF CHITOSAN – BASED MATERIALE IN MEDICINE

Polysaccharides are macromolecular polymers that manifest ability toward the forming of fibres, film and coatings. Some of their specific properties like biodegradability and biocompatibility make them suitable for medical application. Chitin, chitosan and alginates are basic polymers mostly used in the preparation of medical biomaterials. In the Institute of Biopolymers and Chemical Fibres (IBWCh) multidirectional investigations are in full swing concerned with the use medical of polysaccharides and their various useful forms. The research includes amongst: multifunctional dressing materials, implants and other polysaccharide biomaterials

Lesion and stimulation of the ventral tegmental area increases cholinergic activity in the rat brain

Our previous study indicated that unilateral lesion of the ventral tegmental area (VTA) facilitates contralateral VTA stimulation-induced feeding or exploration. The present study was aimed to determine the possible role of the central cholinergic systems in this effect. Immunohistochemistry for choline acetyltransferase (ChAT) was used to measure the number of active cholinergic neurons in their major groups (Ch1-Ch6) and in striatal regions in rats subjected to unilateral electrocoagulation and contralateral VTA electrical stimulation (L/S group) in comparison to the unilaterally stimulated (S), unilaterally lesioned (L) and sham (Sh) groups. The study showed that unilateral VTA lesion increased (as compared to Sh group) the number of ChAT+ neurons in the Ch1-Ch3 and unilateral VTA stimulation increased the number in the Ch1 and the ventral pallidum only. The most sensitive to these changes in the mesolimbic system were cholinergic structures providing hippocampal afferentation. Surprisingly, there was no significant increase in the number of ChAT+ neurons in the L/S group. The obtained results did not confirm any evident influence of the cholinergic systems on the VTA lesion-induced facilitation of the behavioral response evoked by contralateral VTA stimulation

Dimethyl Fumarate Alleviates Adult Neurogenesis Disruption in Hippocampus and Olfactory Bulb and Spatial Cognitive Deficits Induced by Intracerebroventricular Streptozotocin Injection in Young and Aged Rats

The disorder of adult neurogenesis is considered an important mechanism underlying the learning and memory impairment observed in Alzheimer’s disease (AD). The sporadic nonhereditary form of AD (sAD) affects over 95% of AD patients and is related to interactions between genetic and environmental factors. An intracerebroventricular injection of streptozotocin (STZ-ICV) is a representative and well-established method to induce sAD-like pathology. Dimethyl fumarate (DMF) has antioxidant and anti-inflammatory properties and is used for multiple sclerosis treatment. The present study determines whether a 26-day DMF therapy ameliorates the disruption of adult neurogenesis and BDNF-related neuroprotection in the hippocampus and olfactory bulb (OB) in an STZ-ICV rat model of sAD. Considering age as an important risk factor for developing AD, this study was performed using 3-month-old (the young group) and 22-month-old (the aged group) male Wistar rats. Spatial cognitive functions were evaluated with the Morris water maze task. Immunofluorescent labelling was used to assess the parameters of adult neurogenesis and BDNF-related neuroprotection in the hippocampus and OB. Our results showed that the STZ-ICV evoked spatial learning and memory impairment and disturbances in adult neurogenesis and BDNF expression in both examined brain structures. In the aged animals, the deficits were more severe. We found that the DMF treatment significantly alleviated STZ-ICV-induced behavioural and neuronal disorders in both age groups of the rats. Our findings suggest that DMF, due to its beneficial effect on the formation of new neurons and BDNF-related neuroprotection, may be considered as a promising new therapeutic agent in human sAD

Lesion of the ventral tegmental area amplifies stimulation-induced Fos expression in the rat brain

Unilateral lesions of the ventral tegmental area (VTA), the key structure of the mesolimbic system, facilitate behavioral responses induced by electrical stimulation of the VTA in the contralateral hemisphere. In search of the neuronal mechanism behind this phenomenon, Fos expression was used to measure neuronal activation of the target mesolimbic structures in rats subjected to unilateral electrocoagulation and simultaneously to contralateral electrical stimulation of the VTA (L/S group). These were compared to the level of mesolimbic activation after unilateral electrocoagulation of the VTA (L group), unilateral electrical stimulation of the VTA (S group) and bilateral electrode implantation into the VTA in the sham (Sh) group. We found that unilateral stimulation of the VTA alone increased the density of Fos containing neurons in the ipsilateral mesolimbic target structures: nucleus accumbens, lateral septum and amygdala in comparison with the sham group. However, unilateral lesion of the VTA was devoid of effect in non-stimulated (L) rats and it significantly amplified the stimulation-induced Fos-immunoreactivity (L/S vs S group). Stimulation of the VTA performed after contralateral lesion (L/S) evoked strong bilateral induction of Fos expression in the mesolimbic structures involved in motivation and reward (nucleus accumbens and lateral septum) and the processing of the reinforcing properties of olfactory stimuli (anterior cortical amygdaloid nucleus) in parallel with facilitation of behavioral function measured as shortened latency of eating or exploration. Our data suggest that VTA lesion sensitizes mesolimbic system to stimuli by suppressing an inhibitory influence of brain areas afferenting the VTA

Hemostatic, Resorbable Dressing of Natural Polymers-Hemoguard

Investigations are presented for the preparation of a model hemostatic dressing that would exhibit an adequate hemostatic capacity in injuries and surgical wounds, an antibacterial activity to prevent primary and secondary infections, and offer safety in use. The Hemoguard dressing has been designed as a powder prepared from the complex chitosan/alginate Na/Ca in the form of micro- and nano-fibrids. Useful antibacterial and hemostatic properties of Hemoguard, which would qualify the material as first aid dressing and a temporary protection of injury wounds in field conditions, were assessed. Biocompatibility of the dressing was confirmed by biological in vitro examinations

The Redox Balance in Erythrocytes, Plasma, and Periosteum of Patients with Titanium Fixation of the Jaw

Titanium miniplates and screws are commonly used for fixation of jaw fractured or osteotomies. Despite the opinion of their biocompatibility, in clinical practice symptoms of chronic inflammation around the fixation develop in some patients, even many years after the application of miniplates and screws. The cause of these complications is still an unanswered question. Taking into account that oxidative stress is one of the toxic action of titanium, we have evaluated the antioxidant barrier as well as oxidative stress in the erythrocytes, plasma and periosteum covering the titanium fixation of the jaw. The study group was composed of 32 patients aged 20–30 with inserted miniplates and screws. The antioxidant defense: catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase-1 (SOD1), uric acid (UA), total antioxidant capacity (TAC), as well as oxidative damage products: advanced oxidation protein products (AOPP), advanced glycation end products (AGE), dityrosine, kynurenine, N-formylkynurenine, tryptophan, malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), total oxidant status (TOS), and oxidative status index (OSI) were evaluated. SOD1 activity (↓37%), and tryptophan levels (↓34%) showed a significant decrease while AOPP (↑25%), TOS (↑80%) and OSI (↑101%) were significantly elevated in maxillary periosteum of patients who underwent bimaxillary osteotomies as compared to the control group. SOD-1 (↓55%), TAC (↓58.6%), AGE (↓60%) and N-formylkynurenine (↓34%) was statistically reduced while AOPP (↑38%), MDA (↑29%), 4-HNE (↑114%), TOS (↑99%), and OSI (↑381%) were significantly higher in the mandibular periosteum covering miniplates/screw compared with the control tissues. There were no correlations between antioxidants and oxidative stress markers in the periosteum of all patients and the blood. As exposure to the Ti6Al4V titanium alloy leads to disturbances of redox balance in the periosteum surrounding titanium implants of the maxilla and the mandible so antioxidant supplementation should be recommended to the patients undergoing treatment of dentofacial deformities with the use of titanium implants. The results we obtained may also indicate a need to improve the quality of titanium jaw fixations through increase of TiO2 passivation layer thickness or to develop new, the most highly biodegradable materials for their production

Haemostatic, resorbable dressing of natural polymers - hemoguard

Investigations are presented in the preparation of a first aid haemostatic dressing that would exhibit an adequate haemostatic capacity in injuries and surgical wounds, an antibacterial activity to prevent primary and secondary infections, and offer safety in us