Hasan Bilgili

Evaluation of sericin/collagen membranes as prospective wound dressing biomaterial.

Sericin, a silk protein, has high potential for use in biomedical applications. In this study, wound dressing membranes of Sericin (S) and Collagen (C) were prepared by glutaraldehyde cross-linking at S/C; 2:1, 1:1, 1:2, and 0:1 weight ratios. They were stable in water for 4 weeks. However, increasing the proportion of sericin had decreasing effect on the membrane stability. Water swelling property of membranes was enhanced with sericin. The highest water swelling was obtained in 1:1 group (9.06 g/g), but increasing collagen or sericin content in the membranes had a diminishing effect. Highest water vapor transmission rate was obtained with 1:2 group (1013.80 g/m(2)/day). Oxygen permeability results showed that 1:2 (7.67 mg/L) and 2:1 (7.85 mg/L) S/C groups were better than the other groups. While sericin decreased the tensile strength and elongation of membranes, it increased modulus. Sericin also increased brittleness of membranes, but their UTS range (24.93-44.92 MPa) was still suitable for a wound dressing. Membranes were not penetrable to microorganisms. Cytotoxicity studies showed that fibroblasts and keratinocytes attached and gained their characteristic morphologies. They also proliferated on membranes significantly. After 1 week of subcutaneous implantation, a fibrous capsule formed around all membranes with an acute inflammation. Sericin containing membranes showed signs of degradation (at 2nd week), while collagen only membranes remained largely intact. Eventually, sericin containing membranes degraded in 3 weeks with moderate inflammatory response. Overall results suggest that sericin/collagen membranes would be favorable as wound dressing material when sericin ratio is less than or equal to the collagen component.

Hemostatic Efficacy of Ankaferd Blood Stopper® in a Swine Bleeding Model

Objective: The purpose of this study was to show the hemostatic effect of spray, solution and tampon forms of Ankaferd Blood Stopper® (ABS), a unique medicinal plant extract historically used as a hemostatic agent in Turkish folklore medicine, in a porcine bleeding model. Materials and Methods: Two 1-year-old pigs were used as bleeding models for superficial and deep skin lacerations, grade II liver and spleen injuries, grade II saphenous vein injury and grade IV saphenous artery injury. Spray, solution or tampon forms of ABS were applied after continuing bleeding was confirmed. The primary outcome was time to hemostasis. Volume of blood loss was not measured. The pigs were euthanized at the end of the experiment. Results: Spray or direct application of ABS solution resulted in instant control of bleeding in superficial and deep skin lacerations as well as puncture wounds of the liver. A 40-second application of ABS tampon was sufficient to stop bleeding of skin lacerations, while 1.5- and 3.5-min applications were used to control hemorrhage from the saphenous vein and artery, respectively. No rebleeding was observed once hemostasis was achieved. However, repeated applications of ABS solution and tampon were only temporarily effective in the hemostasis of spleen injury. Conclusions: The data showed that ABS was an effective hemostatic agent for superficial and deep skin lacerations and minor/moderate trauma injuries in a porcine bleeding model.

Ultrastructural and Morphological Analyses of the In Vitro and In Vivo Hemostatic Effects of Ankaferd Blood Stopper

Ultrastructural and morphological analyses of a novel hemostatic agent, Ankaferd Blood Stopper (ABS), in comparison to its in vitro and in vivo hemostatic effects were investigated. High-resolution scanning electron microscopy (SEM) images accompanied with morphological analysis after topical application of ABS revealed a very rapid (<1 second) protein network formation within concurrent vital erythroid aggregation covering the classical coagulation cascade. Histopathological examination revealed similar in vivo ABSinduced hemostatic network at the porcine hepatic tissue injury model. Instantaneous control of bleeding was achieved in human surgery-induced dental tissue injury associated with primary and secondary hemostatic abnormalities. Ankaferd Blood Stopper could hold a great premise for clinical management of surgery bleedings as well as immediate cessation of bleeding on external injuries based on upcoming clinical trials.

Oral Systemic Administration of Ankaferd Blood Stopper Has No Short-Term Toxicity in an In Vivo Rabbit Experimental Model

Background: Ankaferd blood stopper (ABS) is a standardized herbal extract obtained from 5 different plants. In Turkey, it has been approved for local topical applications in external postsurgical and postdental surgery bleedings. Ankaferd blood stopper, besides its hemostatic activity, has in vitro anti-infectious and antineoplastic actions. Objective: The aim of this study was to assess short-term hematological and biochemical safety following the oral systemic administration of ABS to rabbits. Methods: Twelve rabbits (aged 6-12 months) were included to test the safety of oral ABS. Animals were divided into 4 groups, which had ABS administered orally at doses of 1, 3, 6, and 9 mL, irrespective of their weight. The general well-being and feeding patterns of the animals were observed for a period of 7 days. Blood samples (5.5 mL) were obtained just before oral administration, on days 1 and 4. Results: During the observation period of 7 days, none of the animals showed any abnormal behavior or deviation from the normal. Acute mucosal toxicity, hematotoxicity, hepatotoxicity, nephrotoxicity, and biochemical toxicity were not observed during the short-term follow-up of the animals. Conclusions: No signs of toxicity were observed in rabbits during short-term study with oral ABS administration.

Thrombus Localization by Using Streptokinase Containing Vesicular Systems

Our research focused on the preparation of vesicular drug delivery systems, such as liposomes, noisomes, and sphingosomes, for achieving slow release of entrapped proteins in the circulation to increase half-life, to mask immunogenic properties, and to protect against loss of enzymatic activity. We prepared, characterized, and monitored the biodistribution of three types of vesicular systems (liposomes, niosomes, and sphingosomes) containing streptokinase. For biodistribution stuides, radiolabelled streptokinase dispersions were injected into the ear vein of female rabbits in the weight of 2.5–3 kg weight. Following the application, rabbits were sacrificed, then organs of these animals were removed and radioactivity of organs was measured by well-type gamma counter. The comparison of the biodistribution results of the free streptokinase with the streptokinase vesicles showed that incorporation of the enzyme into the vesicles changed the biodistribution of the drug and by the entrapment of the streptokinase in the vesicles, thrombus uptake and imaging quality were improved.

Enhanced efficacy of diclofenac sodium-loaded lipogelosome formulation in intra-articular treatment of rheumatoid arthritis

Recent research into the complex and varied components of rheumatoid arthritis (RA) is leading to the development of more effective targets for pharmaceutical approach than even before. Current treatment of RA frequently includes the use of nonsteroidal anti-inflammatory drugs, such as Diclofenac sodium (DFNa) in spite of the severe adverse effects. Local application and incorporation of the drugs in liposome based formulations may reduce those side effects and improve the efficacy of drugs by reducing the availability of them in systemic circulation and increasing accumulation and retention time in the sites of inflammation. Herein, anti-inflammatory efficacy of the DFNa containing lipogelosome formulations (L1J1) was evaluated and found that L1J1 elicits a better anti-inflammatory efficacy after a single dose i.a administration in comparison with commercial product, VE-CP®, which is used topically. Histopathological examination of the opened joints showed that joints treated with L1J1, had significantly (p < 0.05) lower scores than contra lateral control joints for inflammatory changes in the synovium. These results were also confirmed by biodistribution studies.

Pentoxifylline effects on acute and late complications after radiotherapy in rabbit

Soft tissue damages after radiotherapy are an uncommon but serious complication. Late damage after radiation is the principal dose-limiting factor in radiation therapy today and is dependent on vascular pathology as a result of radiation. Pentoxifylline is a methylxanthine derivative that produces dose-related improvement in blood flow, lower blood viscosity, improved erythrocyte flexibility, and increased tissue oxygen levels. An agent that increases blood flow and tissue oxygen content may contribute to enhanced healing of soft tissue pathology. Sixteen adult New Zealand rabbits were separated into 2 groups and inspected for 30 weeks after radiation. We noted acute and chronic reactions and pathologic changes in different regions of the head and neck of rabbits. The prophylactic administration of pentoxifylline in the postirradiation period can reduce late soft tissue pathology, but it does not affect acute radiation reactions.

Biomechanical and histological outcome of combined raloxifene–estrogen therapy on skeletal and reproductive tissues

Estrogen replacement is a potent therapy for postmenopausal osteoporosis. However, its carcinogenic effects on breasts and the uterus limit its utilization. Raloxifene has estrogen-like effects on bones without the carcinogenic symptoms on breast or uterine tissue. Their individual effects are well characterized, but the results of their interaction remains elusive. In this work, we investigate the consequences of a combined raloxifene/estrogen therapy on bone and uterus with experimental osteoporosis. 40 Wistar rats began treatment 3 months post-ovariectomy. Estrogen and raloxifene were administered 0.03 mg/kg/day and 1.5mg/kg/day separately and together for 5 times per week for 12 weeks. Biomechanical tests and bone mineral density measurements, histology of uterus, and blood markers were analyzed. The co-administration group had higher toughness and ultimate strength than the ovariectomized controls (P<0.01). E+R had better biomechanical properties than the single treatments; yet the differences were not significant. Uterus histology signified high degeneration in the estrogen group. The raloxifene group had less degeneration but higher vascularization. Less immune reaction and vascularization were observed in the group with combined dosage than in those with individual treatments. Hence, the uterus of the combined treatment had fewer side effects than the ones that were individually treated. Mutual antagonization might be possible between raloxifene and estrogen, and that might have caused a decrease in the adverse effects. Overall, combined therapy might be useful to minimize the individual side effects of raloxifene and estrogen on the uterus and still provide bone strength and toughness.

The effect of gamma radiation sterilization on dental biomaterials

Biomaterials are used in the field of bone and tissue engineering, orthopaedics and dentistry. Dental biomaterials including commercially available biodegradable materials act as physical barriers to help quicker healing while stimulating the regeneration of periodontal tissues, which is defined as Guided Tissue Regeneration (GTR). Amongst natural and synthetic biomaterials, collagen and aliphatic polyesters, such as polylactic acid (PLA) and poly (lactic-co-glycolic) acid (PLGA) are the most frequently used biomaterials for regenerative therapies due to their excellent biocompatibility and biodegradability. Due to their resorption in the body and interaction with biological systems, the GTR membranes must be sterile and pyrogen free. The sterility and apyrogenicity of the GTR membranes before human use is a regulatory requirement, however the sterilization of biomaterials is challenging due to the physicochemical changes and toxic residues with the commonly used sterilization techniques. The purpose of the present study was to evaluate the effect of gamma radiation and ethylene oxide sterilization on dental biomaterials with analytical, microbiological and histological examinations. PLGA-based GTR dental biomaterial is selected as the most gamma stable membrane according to the FTIR, DSC, TGA, and SEM results. This dental membrane was sterilized with ethylene oxide (EtO) and the effect of sterilization method on PLGA-based membrane was also investigated. Animal experiments were carried out to evaluate the regenerative properties and inflammatory responses of gamma and EtO sterilized PLGA-based GTR membrane after implantation. Histological examinations showed that resorption and bone formation of gamma sterilized PLGA-based GTR membrane was completed in 12 weeks without any inflammatory response; while only 60.095 ± 2.019% of new bone formation was observed with EtO sterilized one. Gamma sterilized PLGA membrane had significantly faster (P < 0.05) resorption and bone formation in comparison with EtO sterilization. In conclusion, the PLGA-based biomaterials could be sterilized safely and time- and cost-effectively with validated radiation doses for the tissue engineering applications.

Prospective evaluation of Vitamin K2, Raloxifene and their co-administration in osteoporotic rats

In this study, therapeutic effects of Vitamin K2, Raloxifene and their co-administration on bone, uterus, blood and weight profiles were investigated with an ovariectomized rat model. Forty Wistar rats were divided into five groups (n=8): Raloxifene (R), Vitamin K2 (K), Raloxifene+Vitamin K2 (R+K), ovariectomized controls (OVX) and Sham-operated controls (Sham). Treatment began 3 months after ovariectomy. Vitamin K2 and Raloxifene were administered 30 and 1.5 mg/kg/day separately and in combination five times per week for 12 weeks. All treatment groups had significantly higher ultimate strength and energy absorption capacity (P<0.05) than ovariectomized controls in both femur and tibia. Histological results showed that treatment groups had healthy lumen structure, whereas OVX had degeneration. Adverse effects which were seen in individual treatments (myometrium weakening in K, endometrium weakening in R, and ALP increase in group R) were not observed in the R+K group implying a synergistic effect of these two agents when they are co-administered. According to blood analysis, ALP values were significantly high in Raloxifene-only group (P<0.0001). This effect is suppressed in the co-administered group. In summary, the groups R, K and R+K had significantly higher ultimate strength and less susceptibility to fracture than ovariectomized controls. In summation, Vitamin K2 treated groups (either in single or combined with Raloxifene) had considerable biomechanical performance and reproductive tissue profile indicating that this agent is prospectively effective in osteoporosis management.