Novel tamarind seed polysaccharide-alginate mucoadhesive microspheres for oral gliclazide delivery: in vitro-in vivo evaluation.

Novel tamarind seed polysaccharide (TSP)-alginate mucoadhesive microspheres were prepared using TSP and alginate as blend in different ratios with different calcium chloride (CaCl(2)) concentration as a cross linker by ionotropic gelation. The prepared microspheres were of spherical shape having rough surfaces, and average particle sizes within the range of 752.12 ± 6.42 to 948.49 ± 20.92 µm. The drug entrapment efficiency of these microspheres were within the range between 58.12 ± 2.42 to 82.78 ± 3.43% w/w. Fourier transform infrared (FTIR) studies indicated that there were no reactions between gliclazide, and polymers (TSP, and sodium alginate) used. Different formulations of gliclazide loaded TSP-alginate microspheres showed prolonged in vitro release profiles of gliclazide over 12 hours in both stomach pH (pH 1.2), and intestinal pH (pH 7.4). It was found that the gliclazide release in gastric pH was comparatively slow and sustained than intestinal pH. These TSP-alginate microspheres also exhibited good mucoadhesivity. The in vivo studies on alloxan-induced diabetic rats (Animal Ethical Committee registration number: IFTM/837ac/0160) demonstrated the significant hypoglycemic effect of selected formulation of TSP-alginate mucoadhesive microspheres containing gliclazide on oral administration. This developed gliclazide loaded new TSP-alginate mucoadhesive microspheres may be very much useful for prolonged systemic absorption of gliclazide for proper maintaining blood glucose level and advanced patient compliance.

Mussel-mimetic tissue adhesive for fetal membrane repair: a standardized ex vivo evaluation using elastomeric membranes.

OBJECTIVE: Iatrogenic preterm premature rupture of membranes (iPPROM), the main complication of invasive interventions in the prenatal period, seriously limits the benefit of diagnostic or surgical prenatal procedures. This study aimed to evaluate preventive plugging of punctured fetal membranes in an ex vivo situation using a new mussel-mimetic tissue adhesive (mussel glue) to inhibit leakage. METHODS: A novel biomechanical test device that tests the closure of injured membranes under near-physiological conditions was used. Mussel glue, a poly(ethylene glycol)-based hydrogel, was used to seal membrane defects of up to 3 mm in mechanically well-defined elastomeric membranes with three different degrees of stiffness. RESULTS: Elastomeric test membranes were successfully employed for testing mussel glue under well-defined conditions. Mussel glue plugs were distended by up to 94%, which translated to an improved sealing efficiency on elastomeric membranes with high stiffness. For the stiffest membrane tested, a critical burst pressure of 48 mbar (36 mmHg) was accomplished in this ex vivo setting. CONCLUSIONS: Mussel glue appears to efficiently seal membrane defects under well-standardized ex vivo conditions. As repaired membranes resist pressures measured in amniotic cavities, mussel glue might represent a novel sealing method for iatrogenic membrane defects.

[Extraction and application of Perna viridis foot protein as bioadhesive].

Mussel adhesive proteins have attracted increasing interests for their potential use as environmentally friendly bioadhesives in medicine and aqueous conditions. In this study, surface coating analysis, quartz crystal microbalance (QCM), cell and bone tissue adhesion and cytotoxicity assay were used to study the properties of the Perna viridis foot proteins (Pvfp) extract as bioadhesive. The results of coating ability on various materials and QCM analysis revealed that Pvfp extract has comparable or superior adsorbtion ability to that of Cell-Tak (the naturally extracted MAP mixture from Mytilus edulis, and has been commercialized), and also, the cell adhesion ability of Pvfp extract was stronger than that of Cell-Tak and poly-L-lysine. No cytotoxicity was detected using human HeLa and 293T cells. Furthermore, broken bones of mouse could be stuck together by use of Pvfp extract. In bulk-scale adhesion tests, Pvfp extract showed much greater tensile strength than did fibrin glue for conglutinating poly (vinl chloride) sticks and for binding together pig's femur segments. These results suggested that Pvfp extract be an efficient cell and tissue adhesive in biotechnological application and it might be a potential bioadhesive in medical practice.

Head glands of Monogenoidea: morphology, functionality, and potentialities in industrial production of surgery bioadhesives.

A review of the structure and functionality of monogenoidean head glands is provided. The unique features of the biochemical methods used by parasites to attach to, or detach from, fish hosts are highlighted. The potential use of monogenoidean cephalic secretions in the surgical field, and particularly in the production of bioadhesives, is suggested and critically supported by comparison with other available hemostatic agents.

A new fibrin sealant from Crotalus durissus terrificus venom: applications in medicine.

Fibrin sealant, a widely available tissue adhesive, has been used since 1940 in a variety of clinical applications. Commercially available fibrin sealant products are synthesized from bovine thrombin and human fibrinogen, which may transmit infectious diseases, and recipients may also develop antibodies against bovine thrombin. Bearing these disadvantages in mind, a new fibrin sealant was developed in 1989 by a group of researchers from the Center for the Study of Venoms and Venomous Animals, in Sao Paulo State, Brazil. The main purpose was to produce an adhesive fibrin without using human blood, to avoid transmitting infectious diseases. The components of this novel sealant were extracted from large animals and a serine proteinase extracted from Crotalus durissus terrificus snake venom. The applicability of this sealant was tested in animals and humans with beneficial results. The new fibrin sealant can be a useful tool clinically due to its flexibility and diversity of applications. This sealant is a biological and biodegradable product that (1) does not produce adverse reactions, (1) contains no human blood, (3) has a good adhesive capacity, (4) gives no transmission of infectious diseases, and (5) may be used as an adjuvant in conventional suture procedures. The effectiveness of this new fibrin sealant is reviewed and its development and employment are described.

Rapid preparation of small-volume autologous fibrinogen concentrate and its same day use in bleb leaks after glaucoma filtration surgery.

The authors evaluated small-volume preparation of autologous fibrin glue (AFG) and same day use in postglaucoma filtration surgery patients with Seidel positive bleb leaks and determined fibrinogen concentrations in autologous fibrinogen concentrates (AFCs) from 10 volunteers. Thirty milliliters of blood was centrifuged (5 min, 2400 x g); plasma was frozen (5 min-ethanol and ice), thawed (1-6 C, 30-60 min), and centrifuged (10 min, 5 C, 2800 x g); and the precipitate was transferred to a 1.0-ml tuberculosis syringe. Thrombin (1000 U) was dissolved (0.8 sterile water, 0.2 ml aminocaproic acid) and warmed (37 C). Average preparation time was 90 minutes. Alternating drops of AFC and thrombin were applied to bleb leaks until AFC clotted. Seidel testing with fluorescein determined success. AFC was prepared from 10 volunteers and fibrinogen was measured. AFG was initially successful with two (Seidel negative) eyes; one eye remained negative. AFG was unsuccessful in one briskly Seidel-positive leak. Mean +/- SD fibrinogen concentration in AFCs from the 10 volunteers was 2314 +/- 643 mg/dl (range 1608-3431 mg/dl). AFG may successfully close bleb leaks in outpatient settings. Brisk aqueous flow may impair effectiveness of AFG. Fibrinogen concentrations were comparable with previous reports.

Fibrin sealant in the United States: clinical use at the University of Virginia.

Fibrin sealant use in the United States has been limited because of the lack of a commercially available, government approved product. However, the significant need and usefulness of this material at the time of surgical operations has stimulated alternative sources of production. At the University of Virginia, the Blood Bank produces concentrated single donor or autologous fibrinogen for use with commercially available bovine thrombin in order to make fibrin sealant. The hemostatic and adhesive properties of fibrin sealant have been used since 1985 at this Center in a wide variety of operations with over 90% effectiveness. This chapter will review the development and role of this material in modern clinical surgery at this institution. The advantages, disadvantages, and never applications of this substance in various forms will be assessed. The role of fibrin sealant is increasing in this country and additional developmental work is continuing. The era of a commercially available product in the United States appears to be on the horizon.

Protein-based medical adhesives.

There are many naturally occurring adhesive proteins which have potential for application in medicine and dentistry. Cloning and expression of their genes enables the modes of action of these proteins to be better understood and increases their availability for practical applications. This article concentrates on the adhesive protein from the blue mussel Mytilus edulis but also describes medical adhesives based on fibrin isolated from human blood.

Autologous fibrin tissue adhesive for peripheral nerve anastomosis.

The sciatic nerve in rabbits was exposed, transected, and repaired using either of two methods. The experimental group had an autologous fibrin-based adhesive repair. The control group had conventional perineural suturing. The autologous tissue glue is similar in composition, handling, and performance to the commercially available European product Tisseel. It can be prepared quickly without sophisticated equipment or expense. Autologous glue obviates the risk of transmissible disease that has precluded approval of the commercial product for use in the United States. The glued anastomosis can be performed with accurate apposition and minimal trauma to the nerve. By making a fibrin cocoon, the anastomosis can be insulated. This provides some of the benefits of sheathed anastomosis while minimizing foreign body reaction. Functional evaluation and histologic results comparing the amount of anastomotic fibrosis, axonal regeneration, and alignment of fascicles showed glue to be as good as, if not superior to, conventional suture technique.

Fibrin glue from stored human plasma. An inexpensive and efficient method for local blood bank preparation.

European surgeons have used fibrin glue extensively during thoracic, cardiovascular, and general surgical operations. Until now, however, it has been available only as a commercial preparation made from pooled human plasma, and it has not been approved by the U.S. Food and Drug Administration for use in the United States because of a high associated risk of hepatitis and acquired immune deficiency syndrome. Methods of obtaining fibrinogen, an essential component of fibrin glue, from cryoprecipitate or fresh frozen plasma have been published recently. However, the cryoprecipitate method results in relatively low concentrations of fibrinogen, which can reduce glue effectiveness. The fresh frozen plasma method is more expensive and does not meet the standards of the American Association of Blood Banks for the "closed" system required for safe handling and management of blood component products. Both the cryoprecipitate and the fresh frozen plasma methods result in waste of unstable clotting factors. These factors are necessary to replace human plasma clotting deficiencies but are not necessary for the production of fibrin glue. The authors have developed an efficient, high-concentration blood bank method for producing and maintaining a local supply of a safer and less expensive but equally effective material derived from stored human plasma. This material is produced using approved blood bank techniques for a "closed" system in blood component production, thus reducing the risks of contamination and infection, and its fibrinogen concentration is higher than that of standard cryoprecipitate. The cost of 1 unit of this fibrin glue is comparable to that for 1 unit of cryoprecipitate and less than that for 1 unit of fresh frozen plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Preparation of fibrin glue from single-donor fresh-frozen plasma.

Fibrin glue is used widely in Europe as a tissue sealant and hemostatic agent. The European glue is prepared commercially from pooled human blood. It is not available in this country because of the risk of transmission of hepatitis B, acquired immune deficiency syndrome, and other blood-transmitted diseases. We describe a cryoprecipitation technique for preparation of fibrin glue from single-donor fresh-frozen plasma. This technique enables the glue to be made in large quantities with no greater risk of disease transmission than with that from the transfusion of single-unit fresh-frozen plasma. We have found that the glue is a useful tool in surgery. By helping to control difficult bleeding, its use can decrease the need for blood transfusions and shorten operating room time. It also is effective as a means to pretreat highly porous vascular prostheses that currently are used infrequently because of bleeding. These porous grafts offer potential advantages in handling, suturing, and long-term patency. This new technique of fibrin glue preparation may make this useful surgical adjunct as readily available in this country as it is in Europe.

[1st report on the use of an autogenous tissue adhesive in otorhinolaryngology]. / Erste Berichte über die Anwendung eines autogenen Gewebeklebers in der Hals-Nasen-Ohrenheilkunde.

An autogenous tissue glue has been developed at the ENT Department of the University Clinic Graz. It is prepared from the patient's own plasma, and has the following advantages: There is no danger of transmitting infectious diseases, there are no problems with storage, temperature and expiration date. The glue is produced at room temperature and is cheap. The production and application of this autologous tissue glue are described and a first report is given on initial experiences.