Biodegradation and in vivo biocompatibility of rosin: a natural film-forming polymer

The specific aim of the present study was to investigate the biodegradation and biocompatibility characteristics of rosin, a natural film-forming polymer. Both in vitro as well as in vivo methods were used for assessment of the same. The in vitro degradation of rosin films was followed in pH 7.4 phosphate buffered saline at 37°C and in vivo by subdermal implantation in rats for up to 90 days. Initial biocompatibility was followed on postoperative days 7, 14, 21, and 28 by histological observations of the surrounding tissues around the implanted films. Poly (DL-lactic-co-glycolic acid) (PLGA) (50∶50) was used as reference material for biocompatibility. Rate and extent of degradation were followed in terms of dry film weight loss, molecular weight (MW) decline, and surface morphological changes. Although the rate of in vitro degradation was slow, rosin-free films showed complete degradation between 60 and 90 days following subdermal implantation in rats. The films degraded following different rates, in vitro and in vivo, but the mechanism followed was primarily bulk degradation. Rosin films demonstrated inflammatory reactions similar to PLGA, indicative of good biocompatibility. Good biocompatibility comparable to PLGA is demonstrated by the absence of necrosis or abscess formation in the surrounding tissues. The study provides valuable insight, which may lead to new applications of rosin in the field of drug delivery.     

Initial observations on the cellulolytic activities of some fungal isolates

Summary The cellulolytic activities of aTrichoderma sp.,Penicillium sp.,Cladosporium sp.,Trichoderma viride ATCC-24687,Myrothecium roredium, ATCC-28814 and unidentified fungus (F-4) were investigated. TheTrichoderma sp. and the unidentified fungus (F-4) secreted larger amounts of cellulase into the growth medium than the other strains. They also saccharified lignocellulosics more rapidly than the other strains.

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Resumen Se estudió la actividad celulolítica de: une especie deTrichoderma sp.,Penicillium sp.,Cladosporium sp.,Trichoderma viride ATCC-24687,Myrothecium roredium, ATCC-28814, y de un hongo no identificado (F-4).Trichoderma sp. y el hongo no identificado secretaron más cantidad de celulasa al medio de cultivo que las otras cepas estudiadas. Tambien saccarificaron materiales lignocelulósicos más rápidamente que los demás hongos.

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Résumé Les activités cellulolytiques d'unTrichoderma sp., d'unPenicillium sp., d'unCladosporium sp., d'unTrichoderma viride ATCC-24687, d'unMyrothecium roredium et d'une moisissure nonidentifiée (F-4) ont été examinées. La soucheTrichoderma sp et la moisissure non-identifiée (F-4) ont secrété des quantités plus importantes de cellulase dans le milieu du culture que les autres souches. Ces deux souches ont aussi saccharifié la ligno-cellulose plus rapidement que les autres souches.

     

A new method for the dressing of free skin grafts

Using adhesive drapes and a disposable suction drain, a new method for the dressing of free skin grafts has been devised. The graft is compressed by pressure that is equivalent to the negative pressure of the suction drain. This method can apply uniform and constant pressure on the graft. Moreover, the graft can be observed through a transparent drape so that the existence of hematomas can be detected easily.     

Preparation of porcine small intestinal submucosa sponge and their application as a wound dressing in full-thickness skin defect of rat

Small intestinal submucosa (SIS) sponge was prepared by crosslinking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). The prepared SIS sponges exhibited elastic and soft property on touch and were ease to handle. The SIS sponges have the pore diameter of 100-200 microm and an interconnective porous structure. The SIS sponges exhibited high water absorption ability over 8000%. The water uptake of SIS sponges decreased as SIS concentration used to manufacture SIS sponge increased. In wound healing test, SIS sponge attained uniform adherence to the wound surface. The SIS sponges absorbed higher extent of exudation for wound than that covered with Tegaderm as control. Wound area contracted above 80% at the 21st postoperative day. The SIS sponge treated wound was almost completely covered with a thin layer of epidermis at 4 weeks. In addition, the dermal collagen in the wound regenerated at only SIS sponges treated wounds. The progress of granulous tissue formation was faster in SIS sponges as wound dressing than in Tegaderm. In conclusion, we found that the SIS sponges might be a potential material as a wound dressing.     

Initial observations on the organization of the testis of Trisopterus minutus capelanus]

Testis of the Teleostean fish Trisopterus minutus capelanus has been examined to study the organization of the seminiferous tubules and the ultrastructural features of the germ cells. The testis is shown to be composed of seminiferous tubules full of cells: only few of them have just a very narrow lumen. Each tubule is divided by thin septa of connective tissue in zones containing homogeneous cells; such an organization is confirmed by ultrastructural images showing groups of synchronously developing germ cells. By morphological characterization of the germ cells found in each zone, 6 maturation stages have been identified. During spermiogenesis, a progressive shrinkage of germ cells and a nuclear chromatin condensation have been observed. Intercellular bridges, homogeneously dispersed granules of glycogen and groups of mitochondria associated with dense granular material have been described. Such features are present in the earlier stages of spermiogenesis and are retained until the later stages of spermatid differentiation. The spermatozoon shows a lack of acrosome as in many other teleosts previously studied.     

Plasticized polyvinylchloride as a temporary dressing for burns.

Plasticized polyvinylchloride film has been used in this burns unit for a long time for dressings before the ward round, before surgery, and when the burned patient is transferred from the casualty department to the burns unit. Plasticized polyvinylchloride film is easy to use, safe, and causes no pain. Most importantly, in the present financial climate, it is cheap.