[Correlation between uterine scar condition and uterine rupture for pregnancy women after previous cesarean section].

Objective: To investigate the relationship between the previous cesarean scar thickness, previous cesarean scar defect and the occurrence of uterine rupture for pregnancy women after previous cesarean section and to predict the occurrence of uterine rupture in the third trimester for pregnancy women after previous cesarean section by analyzing the lower uterine segment (LUS) situation or quantitatively measure LUS myometrium thickness. Methods: A total of 154 pregnant women who have a prior cesarean from January 2015 to March 2016 were selected, all of them regularly did the prenatal examination in the pregnancy period and finally gave birth in hospital. By the transvaginal sonograph, the LUS myometrium thickness (transverse and longitudinal thickness) and the size of the previous cesarean scar defect were measured in the first trimester, the LUS myometrium thickness (longitudinal thickness) and qualitatively analysis LUS condition were measured in the third trimester. They were divided into two groups according to the pregnancy outcome: uterine rupture group (found in the cesarean operation or during the pregnancy) and without uterine rupture group (including the vaginal delivery women and those without uterine rupture in the cesarean operation period). The sensitivity and specificity of LUS myometrium thickness in the first trimester and the qualitative analysis LUS situation, the quantitative measurement of LUS myometrium thickness in the third trimester were compared in the prediction of occurrence of uterine rupture (dehiscence or complete rupture). Results: The group without uterine rupture included 134 women (6 vaginal delivery and 128 cesarean delivery), and the group with uterine rupture included 20 women (all of them cesarean delivery). The LUS myometrium thickness in the third trimester in the group without uterine rupture was (1.6±0.5) mm, and was (1.1±0.7) mm in the uterine rupture group (P= 0.004). There were no significant difference between two groups in the mean value of age, height, weight, the interdelivery interval, the LUS myometrium thickness (transverse and longitudinal thickness) in the first trimester. Qualitative analysis of LUS condition had higher specificity (99%), higher positive predictive value (92%), higher negative predictive value (94%) and slightly lower sensitivity (60%) than quantitative measure of LUS myometrium thickness in predicting uterine rupture. Conclusions: Measurement of the LUS myometrium thickness in the first trimester is helpful for predicting the occurrence of uterine rupture, so it is not necessary to terminate the pregnancy because of the thin LUS or the little prior cesarean scar defect in the first trimester. However it should be paid close attention to the LUS situation during the whole gestation. Qualitatively analyzing LUS situation is more meaningful than quantitatively measuring LUS myometrium thickness in predicting the uterine rupture in the third trimester.

Identification of the chitinase genes from the diamondback moth, Plutella xylostella.

Chitinases have an indispensable function in chitin metabolism and are well characterized in numerous insect species. Although the diamondback moth (DBM) Plutella xylostella, which has a high reproductive potential, short generation time, and characteristic adaptation to adverse environments, has become one of the most serious pests of cruciferous plants worldwide, the information on the chitinases of the moth is presently limited. In the present study, using degenerated polymerase chain reaction (PCR) and rapid amplification of cDNA ends-PCR strategies, four chitinase genes of P. xylostella were cloned, and an exhaustive search was conducted for chitinase-like sequences from the P. xylostella genome and transcriptomic database. Based on the domain analysis of the deduced amino acid sequences and the phylogenetic analysis of the catalytic domain sequences, we identified 15 chitinase genes from P. xylostella. Two of the gut-specific chitinases did not cluster with any of the known phylogenetic groups of chitinases and might be in a new group of the chitinase family. Moreover, in our study, group VIII chitinase was not identified. The structures, classifications and expression patterns of the chitinases of P. xylostella were further delineated, and with this information, further investigations on the functions of chitinase genes in DBM could be facilitated.

Secretion profiles of venom alkaloids in Solenopsis geminata (Hymenoptera: Formicidae) in Taiwan.

Solenopsis geminata (F.) was introduced into southern Taiwan decades ago and has continued to threaten the residents. Although the venom compositions of various fire ant species have been studied, the effects of environmental cues on the secretion pattern have received relatively little attention in an area with subtropical climate and high humidity, such as Taiwan. This study characterizes the effects of temperature and season on the venom compositions of S. geminata in Taiwan. Pure venom was sampled by using a microcapillary pipette and immersing the whole ant in hexane and subjected to gas chromatography-mass spectrometry analysis. The results showed that the ratio of cis C(11) to trans C(11) alkaloids in major workers was significantly higher than that in minor workers. No significant differences could be found in either the relative alkaloids content or the ratio of cis C(11) to trans C(11) alkaloids in venom of minor workers while rearing at four temperature conditions. Nevertheless, the ratio of cis C(11) to trans C(11) alkaloids in the venom of minor workers was the highest in spring and the lowest in winter. The results also showed that the body length, abdomen length, head length, head width, and venom volume differed significantly between major workers and minor workers of S. geminata. The venom volumes of these two castes were positively correlated with their body sizes.

In vitro surface characterization of a biological patch fixed with a naturally occurring crosslinking agent.

The study was designed to characterize the surface properties (including water contact angle, surface tension, protein adsorption, platelet adhesion, and cellular compatibility) of a biological patch fixed with genipin, a naturally occurring crosslinking agent. Fresh and glutaraldehyde-fixed counterparts were used as controls. It was found that both glutaraldehyde and genipin are effective crosslinking agents for biological tissue fixation. Fixation of biological tissue with glutaraldehyde or genipin significantly increased its hydrophilicity and surface tension and reduced its mol ratio of adsorbed fibrinogen to adsorbed albumin as well as the amount of adhered platelet. There were no significant differences in hydrophilicity, surface tension, the mole ratio of adsorbed fibrinogen to adsorbed albumin, and the amount of platelet adhesion between the glutaraldehyde- and genipin-fixed tissues. However, the cellular compatibilities of fresh and the genipin-fixed tissues were significantly superior to the glutaraldehyde-fixed tissue.

Fabrication and characterization of a sponge-like asymmetric chitosan membrane as a wound dressing.

A novel asymmetric chitosan membrane has been prepared by immersion-precipitation phase-inversion method and evaluated as wound covering. This new type of chitosan wound dressing which consists of skin surface on top-layer supported by a macroporous sponge-like sublayer was designed. The thickness of the dense skin surface and porosity of sponge-like sublayer could be controlled by the modification of phase-separation process using per-evaporation method. The asymmetric chitosan membrane showed controlled evaporative water loss, excellent oxygen permeability and promoted fluid drainage ability but could inhibit exogenous microorganisms invasion due to the dense skin layer and inherent antimicrobial property of chitosan. Wound covered with the asymmetric chitosan membrane was hemostatic and healed quickly. Histological examination confirmed that epithelialization rate was increased and the deposition of collagen in the dermis was well organized by covering the wound with this asymmetric chitosan membrane. The results in this study indicate that the asymmetric chitosan membrane thus prepared could be adequately employed in the future as a wound dressing.

Sodium arsenite induces chromosome endoreduplication and inhibits protein phosphatase activity in human fibroblasts.

Arsenic, strongly associated with increased risks of human cancers, is a potent clastogen in a variety of mammalian cell systems. The effect of sodium arsenite (a trivalent arsenic compound) on chromatid separation was studied in human skin fibroblasts (HFW). Human fibroblasts were arrested in S phase by the aid of serum starvation and aphidicolin blocking and then these cells were allowed to synchronously progress into G2 phase. Treatment of the G2-enriched HFW cells with sodium arsenite (0-200 microM) resulted in arrest of cells in the G2 phase, interference with mitotic division, inhibition of spindle assembly, and induction of chromosome endoreduplication in their second mitosis. Sodium arsenite treatment also inhibited the activities of serine/threonine protein phosphatases and enhanced phosphorylation levels of a small heat shock protein (HSP27). These results suggest that sodium arsenite may mimic okadaic acid to induce chromosome endoreduplication through its inhibitory effect on protein phosphatase activity.

Method for producing coded micro-carrier and test method by using a novel type biochip.

This paper provides a method for producing a novel type coded micro-carrier. A simple and cost effective solution for bio-molecule applications was developed. Application relevant items such as manufacture process, biospecific interaction, and analysis method are discussed. For low cost fabrication, the use of LIGA-like process is suggested. LIGA-like process is used as a dry patterning process in which an intense beam of light from an excimer laser is used to pattern a material directly. This process has found extensive application in the microelectronics industry for patterning of polymer materials. The use of LIGA-like techniques offers two attractive features: first, we can cut the polymer into many tiny micro-carriers with micrometer precision. Second, LIGA-like process allows to encode with high precision spatial information onto the micro-carrier that can be used in the identification of the bio-molecule. This paper gives a description of the basic idea, describes the fabrication of the novel micro-carrier that we called "coded micro-carrier," and of the image processing algorithms used for the analysis of bio-molecules. This study also provides a test method for identifying a bio-molecule, which includes mixing several coded micro-carriers with the hybridized unknown bio-molecules; and identifying the codes on the micro-carrier via image recognition system. The numbers and types of the known micro-carrier can be flexibly adjusted according to the number of tested bio-molecules.

An in vitro model for evaluation of vaporous toxicity of trichloroethylene and tetrachloroethylene to CHO-K1 cells.

Toxicokinetics of trichloroethylene (TCE) and tetrachloroethylene (PER) in culture medium and their toxicity to CHO-K1 cells were investigated by employing an in vitro vapor exposure system. Cells were cultured in a 60 mm petri dish with a 25 mm glass dish glued in the central area. TCE or PER was added to the central glass dish so that it would evaporate and dissolve in the surrounding medium in which cells were growing. The results showed that the concentration of TCE or PER in medium increased significantly within 20 min and then decreased very rapidly with time. After a 24 h incubation, the residual of TCE or PER in the medium was very low, but was displayed in a dose-dependent manner. Treatment of cells with either TCE or PER resulted in a dose- and time-dependent inhibition of cell growth. A significantly increase in the frequency of micronuclei (MN) was also observed with either TCE or PER treatment. Low doses of TCE (5-20 microl) or PER (1-5 microl) significantly enhanced the intracellular glutathione (GSH) level. However, the level of GSH rapidly decreased with higher doses of TCE (40-80 microl) or PER (10-20 microl). Depletion of cellular GSH showed no effect on the sensitivity of cells to TCE or PER treatment. GSH-conjugation has been proposed as an activation mechanism to account for the nephrotoxicity of TCE and PER, however the toxicity of TCE and PER to CHO-K1 cells is probably mediated through a distinct mechanism.

Cellular uptake of trivalent arsenite and pentavalent arsenate in KB cells cultured in phosphate-free medium.

Trivalent arsenite (As(III)) and pentavalent arsenate (As(V)) have been shown to have differential uptake mechanisms. In regular RPMI 1640 medium, As(III) was about 40-fold more toxic to KB oral epidermoid carcinoma cells. However, the cytotoxicity and intracellular accumulation of As(V) were dramatically enhanced, equalling those of As(III) when cells were grown in phosphate-free RPMI medium, As(V) uptake was dose-dependently inhibited by phosphate, mersalyl acid (a membrane sulfhydryl agent), and energy poisons, such as sodium azide and potassium cyanide. These results suggest that As(V) and phosphate share a common transport system. In contrast, As(III) uptake was not affected by the above agents. However, the initial uptake rates of As(III) were linearly correlated with its extracellular concentrations, suggesting that As(III) uptake is probably accomplished through simple diffusion. Our results also show that As(III) and As(V) are excreted from KB cells at a comparable rate, and at least half of As(V) is reduced to the more toxic As(III) prior to excretion into the medium. Therefore, the toxicity of As(V) may in part result from its reduction to As(III).

Arsenite efflux is inhibited by verapamil, cyclosporin A, and GSH-depleting agents in arsenite-resistant Chinese hamster ovary cells.

We have previously demonstrated that arsenite-resistant SA7 cells can extrude arsenite more effectively and completely than their parental Chinese hamster ovary cells. Our present results show that arsenite efflux from SA7 cells is inhibited by chemosensitizing agents to multidrug resistant-associated protein: verapamil and cyclosporin A and by glutathione-depleting agents: dinitrofluorobenzene and diethyl maleate. These results suggest that arsenite extrusion in SA7 cells may be mediated by a GSH-dependent and verapamil- and cyclosporin A-sensitive membrane transport system. Since arsenite extrusion was found dose-dependently inhibited by energy poison [potassium cyanide (KCN)] and an ATPase inhibitor (sodium vanadate), ATP is apparently required for arsenite extrusion in SA7 cells.

Heat shock causes protein aggregation and reduced protein solubility at the centrosome and other cytoplasmic locations.

Heat shock markedly inhibited centrosome staining by antisera raised against the two centrosome-specific proteins, pericentrin and gamma tubulin. The inhibition of anti-pericentrin binding was measured by fluorescence imaging. Heat had the greatest effect on intact cells, followed in sensitivity by centrosomes attached to their companion nucleus, with purified centrosomes being least sensitive. The centrosomal content of pericentrin was measured by immunoprecipitation followed by western blotting. Heat caused the amount of pericentrin in the centrosomal fraction to increase, suggesting that pericentrin did not leave the centrosome during heat shock. Furthermore, the pericentrin of the centrosomal fraction became less soluble after heat shock, and could only be solubilized by the most denaturing condition of boiling in 0.1% SDS. Immunoelectron microscopy revealed a heat-induced increase in the electron-dense material comprising the pericentriolar material (PCM), consistent with protein aggregation. Lastly, in heated cells immunoelectron microscopy demonstrated an increase in the binding of heat shock protein 70 (HSP70) to numerous locations throughout the cytoplasm. These data suggest that heat shock reduces the solubility of centrosomal and other cytoplasmic proteins, most likely through protein aggregation.

In vitro evaluation of the genotoxicity of a naturally occurring crosslinking agent (genipin) for biologic tissue fixation.

The objective of the present study was to evaluate in vitro, using Chinese hamster ovary (CHO-K1) cells, the genotoxicity of genipin, a naturally occurring crosslinking agent. Glutaraldehyde, the most commonly used crosslinking agent for biologic tissue fixation, was employed as a reference chemical. The selected procedures for this evaluation were the micronucleus (MN) and sister chromatid exchange (SCE) assays with or without the addition of a metabolic activation system (S9 mix). Before starting the genotoxicity assays, the maximum noncytotoxic amounts of glutaraldehyde and genipin were determined using the MTT assay. The results obtained in the MTT assay revealed that the cytotoxicity of genipin was significantly lower than that of glutaraldehyde with or without S9 mix. The frequencies of MN observed in the cases drugged with varying concentrations of glutaraldehyde or genipin were not statistically different from those seen in the negative controls (blank) in the presence or absence of S9 mix. However, it was noted that glutaraldehyde significantly inhibited the cell-cycle progression while the cells drugged with genipin did not result in cell-cycle delay. In the SCE assay, the numbers of SCE per cell observed in the cases drugged with varying concentrations of glutaraldehyde were significantly greater than those found in the negative controls with or without S9 mix. Nevertheless, these numbers were still low compared to the numbers of SCE induced by the strong mutagens used as our positive control substances. This suggests that glutaraldehyde may produce a weakly clastogenic response in CHO-K1 cells. In contrast, the numbers of SCE per cell obtained in the cases drugged with genipin were comparable to those observed in the negative controls in those that were except drugged with the highest dose (50 ppm). This suggests that genipin does not cause clastogenic response in CHO-K1 cells provided its concentration is lower than 50 ppm. In conclusion, as far as cytotoxicity and genotoxicity are concerned, genipin is a promising crosslinking agent for biologic tissue fixation.

In vitro evaluation of cytotoxicity of a naturally occurring cross-linking reagent for biological tissue fixation.

A recognized drawback of the currently available chemical cross-linking reagents used to fix bioprostheses is the potential toxic effects a recipient may be exposed to from the fixed tissues and/or the residues. It is, therefore, desirable to provide a cross-linking reagent which is of low cytotoxicity and may form stable and biocompatible cross-linked products. To achieve this goal, a naturally occurring cross-linking reagent -- genipin -- which has been used in herbal medicine and in the fabrication of food dyes, was used by our group to fix biological tissues. The study was to assess the cytotoxicity of genipin in vitro using 3T3 fibroblasts (BALB/3T3 C1A31-1-1). Glutaraldehyde, the most commonly used cross-linking reagent for tissue fixation, was used as a control. The cytotoxicity of the glutaraldehyde- and genipin-fixed tissues and their residues was also evaluated and compared. The observation in the light microscopic examination revealed that the cytotoxicity of genipin was significantly lower than that of glutaraldehyde. Additionally, the results obtained in the MTT assay implied that genipin was about 10000 times less cytotoxic than glutaraldehyde. Moreover, the colony forming assay suggested that the proliferative capacity of cells after exposure to genipin was approximately 5000 times greater than that after exposure to glutaraldehyde. It was noted that the cells seeded on the surface of the glutaraldehyde-fixed tissue were not able to survive. In contrast, the surface of the genipin-fixed tissue was found to be filled with 3T3 fibroblasts. Additionally, neocollagen fibrils made by these fibroblasts were observed on the genipin-fixed tissue. This fact suggested that the cellular compatibility of the genipin-fixed tissue was superior to its glutaraldehyde-fixed counterpart. Also, the residues from the glutaraldehyde-fixed tissue markedly reduced the population of the cultured cells, while those released from the genipin-fixed tissue had no toxic effect on the seeded cells. In conclusion, as far as cytotoxicity is concerned, genipin is a promising cross-linking reagent for biological tissue fixation.

Arsanilic acid-Sepharose chromatography of pyruvate kinase from KB cells.

In the present study, arsanical-based affinity chromatography for pyruvate kinase (PK) isolation was explored. p-Arsanilic acid (4-aminophenyl arsonic acid), which contains an arsonic acid moiety structurally similar to inorganic pentavalent arsenate, was conjugated to Sepharose 4B via its para-amino group to form an As(V)-Sepharose matrix. The cellular proteins from KB cells bound to arsonic acid moieties were eluted by 50 mM sodium arsenate in Tris-HCl buffer (50 mM, pH 7.6). A single protein band with a molecular mass of 58 kDa was shown on a sodium dodecyl sulfate-polyacrylamide gel. By immunoblotting, amino acid sequencing and enzymatic analysis, the sodium arsenate-eluted 58-kDa protein was demonstrated to be a human PK (type M2). By using this one-step As(V)-Sepharose chromatography, PK from KB cells was purified 35.4-fold with a specific activity of 153.15 U/mg protein in the presence of 6 mM fructose-1,6-biphosphate. Although PK was eluted from an As(V)-Sepharose column with sodium arsenate, PK activity was apparently inhibited by the used eluent system, but not by p-arsanilic acid, indicating a specific interaction of As(V) to PK. In summary, our results indicate that As(V)-Sepharose can serve as a simple and efficient chromatographic support for PK purification from KB cells.

Evaluation of gelatin hydrogel crosslinked with various crosslinking agents as bioadhesives: in vitro study.

Bioadhesives are used for tissue adhesion and hemostasis in surgery. A gelatin-resorcinol mixture crosslinked with formaldehyde (GRF glue) and/or glutaraldehyde (GRG) is used for this purpose. Although the bonding strength of the GRF glue to tissue is satisfactory, concerns about the cytotoxicity of formaldehyde are reported in the literature. It was suggested that the cytotoxicity problem of the GRF glue may be overcome by changing its crosslinking method. The study was therefore undertaken to assess the feasibility of using an epoxy compound (GRE glue), a water-soluble carbodiimide (GAC glue), or genipin (GG glue) to crosslink with a gelatin hydrogel as new bioadhesives. GRF glue and GRG glue were used as controls. The results of our cytotoxicity study suggested that the cellular compatibility of the GAC and GG glues was superior to the GRF, GRG, and GRE glues. The gelation time for the GG glue was relatively longer than the GRF and GRG glues, while no gelation time could be determined for the GAC glue. Additionally, it took approximately 17 h for the GRE glue to become adhesive. The GRF and GRG glues had the greatest bonding strengths to tissue among all test adhesives, while the bonding strengths of the GAC and GG glues were comparable. In contrast, there was almost no bonding strength to tissue for the GRE glue. However, the GRF and GRG glues were less flexible than the GAC and GG glues. Subsequent to the bonding strength measurement, each test adhesive was found to adhere firmly to the tissue surface and underwent cohesive failure during the bond breaking. In conclusion, the GRF and GRG glues may be used as tissue adhesives when their ability to bind tissue rapidly and tightly is required; the GAC and GG glues are preferable when the adhesive action must be accompanied with minimal cytotoxicity and stiffness; and the GRE glue is not suitable for bioadhesion in clinical applications.

Feasibility study of a natural crosslinking reagent for biological tissue fixation.

Bioprostheses derived from biological tissues must be chemically modified and subsequently sterilized before they can be implanted in humans. Various crosslinking reagents, including formaldehyde, glutaraldehyde, dialdehyde starch, and epoxy compound, have been used to chemically modify biological tissues. However, these synthetic crosslinking reagents are all highly (or relatively highly) cytotoxic. It is therefore desirable to provide a crosslinking reagent suitable for use in biomedical applications that is of low cytotoxicity and that forms stable and biocompatible crosslinked products. This study evaluates the feasibility of using a naturally occurring crosslinking reagent--genipin--to chemically modify biological tissues. Genipin and its related iridoid compounds, extracted from gardenia fruits, have been used in traditional Chinese medicine for the treatments of jaundice and various inflammatory and hepatic diseases. In this feasibility study, the cytotoxicity of genipin and the crosslinking characteristics of genipin-fixed biological tissues were investigated. Fresh porcine pericardia procured from a slaughterhouse were used as raw materials. Glutaraldehyde and an epoxy compound (ethylene glycol diglycidyl ether), which has been used extensively in developing bioprostheses, were used as controls. It was found that the cytotoxicity of genipin was significantly lower than that of glutaraldehyde and the epoxy compound. The amino acid residues in the porcine pericardium that may react with genipin were lysine, hydroxylysine, and arginine. Additionally, the genipin-fixed tissue had a mechanical strength and resistance against enzymatic degradation comparable to the glutaraldehyde-fixed tissue. This suggests that genipin can form stable crosslinked products. The results of this in vitro study demonstrate that genipin is an effective crosslinking reagent for biological tissue fixation.

Stability of a biological tissue fixed with a naturally occurring crosslinking agent (genipin).

The study was undertaken to investigate the stability of a biological tissue fixed with a naturally occurring crosslinking agent (genipin) at distinct elapsed storage durations. The glutaraldehyde-fixed counterpart was used as a control. Porcine pericardia procured from a slaughterhouse were used as raw materials. After fixation, the fixed tissues were sterilized in a graded series of ethanol solutions and thoroughly rinsed in phosphate buffered saline for 1 day, and then stored in a jar containing sterilized water. The samples were taken out and tested for their stability during the durations of 1day through 6 months after storage. The stability of each study group was tested by measuring its tensile strength, free-amino-group content, and denaturation temperature. Additionally, the cytotoxicity of each test sample and its corresponding storage solution were investigated in vitro using 3T3 fibroblasts. The results were examined using a microscope and 3-(4,5-dimethylthiazol-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. It was found that the stability of the genipin-fixed tissue during storage was superior to its glutaraldehyde-fixed counterpart. The differences in stability between the genipin- and glutaraldehyde-fixed tissues during storage may be caused by their differences in crosslinking structure. There was no apparent cytotoxicity for both the genipin-fixed tissue and its corresponding storage solution throughout the entire course of the study, whereas significant cytotoxicity was observed for both the glutaraldehyde-fixed tissue and its storage solution. However, the cytotoxicity of the glutaraldehyde-fixed tissue decreased with increasing elapsed storage duration, whereas that of its corresponding storage solution increased. This suggested that the toxic residues remaining in the glutaraldehyde-fixed tissue leached out slowly into its corresponding storage solution during the course of storage.

In vitro evaluation of a chitosan membrane cross-linked with genipin.

The study was to evaluate the characteristics of a chitosan membrane cross-linked with a naturally-occurring cross-linking reagent, genipin. This newly-developed genipin-cross-linked chitosan membrane may be used as an implantable drug-delivery system. The chitosan membrane without cross-linking (fresh) and the glutaraldehyde-cross-linked chitosan membrane were used as controls. The characteristics of test chitosan membranes evaluated were their cross-linking degree, swelling ratio, mechanical properties. antimicrobial activity, cytotoxicity, and degradability. It was found that cross-linking of chitosan membrane using genipin increased its ultimate tensile strength but significantly reduced its strain-at-fracture and swelling ratio. There was no significant difference in antimicrobial activity between the genipin-cross-linked chitosan membrane and its fresh counterpart. Additionally, the results showed that the genipin-cross-linked chitosan membrane had a significantly less cytotoxicity and a slower degradation rate compared to the glutaraldehyde-cross-linked membrane. These results suggested that the genipin-cross-linked chitosan membrane may be a promising carrier for fabricating an implantable drug-delivery system. The drug-release characteristics of the genipin-cross-linked chitosan membrane are currently under investigation.