[Growth inhibition of Pseudomonas aeroginosa by degree of deacetylation values of chitosan]

Chitin, which entails the most abundant biopolymer in nature after cellulose, having found numerous applications in food processing, cosmetics, agriculture, medical and environment. Natural sources of this polymer are component of exoskeletons of crustaceans and insects as well as cell walls from some bacteria and fungi. Chitosan is a partially deacetylated polymer of chitin, which is more soluble than chitin. The goal of this research is to investigate the diversity of antimicrobial effects of deacetylated chitosan extracted from a certain Persian Gulf shrimp waste [Penaeus semisculcatus], against clinical Pseudomonas aeroginosa. At first, chitin and chitosan were extracted from Penaeus semisulcatus waste by chemical and microbial methods at optimum situation. Deacetylation process of chitin was carried out in alkaline solution at 85°C for 15, 20, 45 minutes and 10 hours respectively and subsequently washed with anhydrous EtOH to remove the residual water. Degree of deacetylation of chitosan samples and its structure were measured by FTIR and Scanning electronic microscopy respectively. Antimicrobial activity was tested against clinical Pseudomonas aeroginosa by agar disc diffusion method. Finally, wound band was made by these compounds and antimicrobial activity was studied invitro. The result of present study confirmed the degree of deacetylation of chitosan samples up to 65% by FTIR method. There was no indication of shift on increasing acetylation degree by heating duration from 15 minutes to 10 hours. Pore diameter was decreased from 0.5-1 micro to 0.065-0.25 micro by the increasing of heating duration. Increased clinical Pseudomonas aeroginosa growth inhibitory up to 50% was obtained by usage of more effective materials up to 3 times on disc. The result of our study showed that there was no relationship between increased heating duration and deacetylation degree. Membrane pores were smaller and antimicrobial activity was more effective by increasing of deacetylation and Ca[+2] presences. The method which was used in this research to prepare porous chitosan membranes with different pore diameter, is suitable and cost effective. Because chitin and chitosan are not toxic, better antimicrobial activity results can be obtained by using more concentrated versions of these components

Therapeutic Effects of Holmium-166 Chitosan Complex in Rat Brain Tumor Model

This study examined the effectiveness of Holmium-166 (Ho-166) chitosan complex therapy for a malignant glioma. Cultured C6 glioma cells (100, 000 in 5microliter) were injected into the caudate/putamen of 200 - 250 gram Wistar rats. Five days later, a Ho-166 chitosan complex was injected into the same site of the glioma injection. Four injection doses were administered: the control group received PBS 10microliter, group 1 received an injection of 100micro Ci (10microliter), group 2 received an injection of 50microCi (5microliter), and group 3 received an injection of 10micro Ci (1microliter). The average tumor volume for each group was 1.385 mm3 for the control group, 0.036 mm3 for group 1, 0.104 mm3 for group 2, and 0.111 mm3 for group 3. Compared with the control group, the size of the tumors in groups 1, 2 and 3 was reduced by an average of 97.4%, 92.5% and 91.9%, respectively. The Kaplan-Meier survival curve of group 2 was the longest, followed by groups 3, group 1 and the control. The mean survival was 22.8, 59, 60, and 44.6 days for the control group and groups 3, 2 and 1, respectively. H-E staining revealed that group 2 yielded the best results in the destruction of the malignant glioma. TUNEL staining and immunohistochemical studies indicated apoptotic features. The Ho-166 chitosan complex proved to be effective in destroying the malignant glioma.

Percutaneous Sclerotherapy of Renal Cysts with a Beta-Emitting Radionuclide, Holmium-166-chitosan Complex

OBJECTIVE: To evaluate the usefulness of a beta-emitting radionuclide (holmium-166-chitosan complex) as a sclerosing agent for the treatment of renal cysts. MATERIALS AND METHODS: Using 10-30 mCi of holmium-166-chitosan complex, 20 renal cysts in 17 patients (14 male and 3 female patients, ranging in age from 47 to 82 years) were treated by percutaneous sclerotherapy under ultrasonographic guidance. The volume of the cysts before and after the sclerotherapy and the percentage change in volume were calculated in order to evaluate the response to therapy, which was classified as either complete regression (invisible), nearly complete regression ( 50 volume%). RESULTS: The follow-up period ranged from 6 to 36 months (mean 28 months). Eighteen cysts (90%) regressed completely (n=11, 55%) or near-completely (n=7, 35%). Partial regression was obtained in one patient (5%) and there was no regression in one patient (5%). No significant complications were encountered. CONCLUSION: The holmium-166-chitosan complex seems to be useful as a new painless sclerosing agent for the treatment of renal cysts with no significant complications.

Características hidrodinámicas de carboximetilquitina y carboximetilquitosana / Hydrodynamic characteristics of carboxymethylchitin and carboxymethylchitosan

Se estudiaron algunas propiedades físico/químicas de 3 derivados carboximetilados, sintetizados a partir de la quitina que se obtiene en Cuba de los carapachos de langostas. Se analiza el comportamiento hidrodinámico de las soluciones de estas sustancias, comprobándose las características de polielectrólito que presentan y se determinan los valores de la masa molar para cada una de ellas

Growth modulation of fibroblasts by chitosan-polyvinyl pyrrolidone hydrogel: implications for wound management?

Wounds in adults and fetuses differ in their healing ability with respect to scar formation. In adults, wounds lacking the epidermis exhibit excess collagen production and scar formation. Fibroblasts synthesize and deposit a collagen rich extracellular matrix. The early migration and proliferation of fibroblasts in the wound area is implicated in wound scarring. We have synthesized a hydrogel from chitosan-polyvinyl pyrrolidone (PVP) and examined its effect on fibroblast growth modulation in vitro. The hydrogel was found to be hydrophilic as seen from its octane contact angle (141.2+/-0.37 degrees). The hydrogel was non-toxic and biocompatible with fibroblasts and epithelial cells as confirmed by the 3(4,5-dimethylthiazolyl-2)-2, 5-diphenyl tetrazolium bromide (MTT) as-say. It showed dual properties by supporting growth of epithelial cells (SiHa) and selectively inhibiting fibro-blast (NIH3T3) growth. Growth inhibition of fibroblasts resulted from their inability to attach on to the hydrogel. These findings are supported by image analysis, which revealed a significant difference (P<0.05) between the number of fibroblasts attached to the hydrogel in tissue culture as compared to tissue culture treated polystyrene (TCPS) controls. However, no significant difference was observed (P>0.05) in the number of epithelial (SiHa) cells attached on to the hydrogel as compared to the TCPS control. Although in vivo experiments are awaited, these findings point to the possible use of chitosan-PVP hydrogels in wound-management.

Dissolution studies on tablets of ibuprofen using chitosan.

An attempt has been made to study the release retardant behaviour of chitosan in ibuprofen tablets. Three different ibuprofen tablets were prepared by using 1,3 and 5% chitosan paste. In vitro evaluations were carried out by using dissolution testing apparatus U.S.P (XXI). The dissolution pattern indicated the role of chitosan in sustained release. Bioavailability studies in male beagle dogs clearly showed the sustained nature of release from chitosan based ibuprofen tablet as compared to conventional ibuprofen marketed formulation. Potential use of chitosan as a new matrix forming material for sustained release preparation has been examined. Chitosan, a natural polysaccharide, has structural characteristics similar to glycosamino glycons. Chitosan has been shown to be non-toxic and biodegradable. It is inexpensive and has been explored in the present investigation as a release retarding agent in ibuprofen tablets.

Quitina y Carboximetilquitosana como agentes desintegrantes / Chitin and carboxymethylchitosan as desintegrating agents

Se realizó un estudio comparativo de la quitina y la carboximetilquitosana como agentes desintegrantes, y se evaluó la influencia ejercida por el método empleado en la elaboración de las tabletas sobre la actividad desintegrante de ambos polímeros. La quitina presentó buenas características como agentes desintegrantes independientemente del método utilizado en la elaboración de las tabletas, mientras que la actividad desintegrante de la carboximetilquitosana fue afectada por el proceso de granulación

Hidrólisis enzimática de Carboximetilquitina y Carboximetilquitosana / Enzymatic hydrolysis of carboxymethylchitin and carboxymethylchitosan

Se estudio la actividad de la lisozima sobre la carboximetilquitina y la carboximetilquitosana mediante el empleo de la viscosimetría y se encontró que ambas son hidrolizadas en condiciones fisiológicas

Investigation with chitosan-oxalate oxidase-catalase conjugate for degrading oxalate from hyperoxaluric rat chyme.

Enteric hyperoxaluria manifests due to hyperabsorption of dietary oxalate, secondary to a variety of chronic gastrointestinal disorders. The potential use of chitosan immobilized oxalate oxidase-catalase conjugate to deplete the oxalate content of food materials, while they are in the digestive tract has been evaluated by treating rat stomach chyme with such an enzyme preparation. Oxalate oxidase, obtained from beet stem, was adsorbed on chitosan along with catalase and then cross linked with glutaraldehyde to stabilize the derivative. This chemical modification of oxalate oxidase brought about a shift in its optimal pH from 4.2 to 3.8 with a marginal increase in its K(m). Compared to native enzyme, the modified oxalate oxidase exhibited increased storage stability, higher thermal stability and enhanced resistance to proteolytic digestion and heavy metal inactivation. These improved properties of the immobilized oxalate oxidase possibly render it suitable for oral administration under hyperoxaluric conditions.

Obtención de dos derivados de quitina / Attainment of two derivatives of chitin

En el presente trabajo de describe la técnica para la obtención de dos derivados de quitina, mediante la reacción de ésta o de su derivado desacetilado con ácido sulfúrico concentrado. Se compara la reactividad de polisacáridos que poseen diferentes grados de desacetilación y se concluye que al aumentar el porcentaje de grupos acetilo se facilita la reacción con el ácido. Se reportan los porcentajes de azufre y nitrógeno para ambos derivados y el comportamiento térmico del sulfato de quitina. El termograma obtenido es comparado con los correspondientes a la quitina y el sulfato de condroitina