Mesenchymal stem cells (MSCs) have the capacity for self-renewal and can form bone, fat, and cartilage. Alginate forms a viscous solution when dissolved in 0.9% saline and gels on contact with divalent cations. The viability and phenotype maintenance of chondrocytes in alginate beads have been well documented. However, little is known about the effect of microencapsulation in alginate on chondrogenesis of MSCs. In this study, human MSCs encapsulated in alginate beads were cultured in serum-free medium with the addition of transforming growth factor (TGF)beta1 (10 ng/mL), dexamethasone (10(-7) M), and ascorbate 2-phosphate (50 microg/mL). The MSCs in alginate assumed a rounded morphology with lacunae around them after 1 week in culture. Cell aggregates were observed at 2 weeks or longer in culture. Histological findings agreed with the clinical determination of hyaline cartilage, characterized by isolated cells with ground substance positive in Safranin-O staining and immunohistochemistry for collagen type II at the periphery of cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) revealed the expression of COL2A1 and COL10A1, marker of chondrocytes and hypertrophy chondrocytes, respectively. These results indicate MSCs in alginate can form cartilage and the MSCs-alginate system represents a relevant model for the study of the molecular mechanisms involved in the chondrogenesis and endochondral ossification.

A novel Fourier transform infrared (FT-IR) microspectrophotometer equipped with differential scanning calorimetry (DSC) was used to investigate the kinetics of intramolecular cyclization of aspartame (APM) sweetener in the solid state under isothermal conditions. The thermal-dependent changes in the peak intensity of IR spectra at 1543, 1283, and 1259 cm(-1) were examined to explore the reaction. The results support that the intramolecular cyclization process in APM proceeded in three steps: the methoxyl group of ester was first thermolyzed to release methanol, then an acyl cation was attacked by the lone pair of electrons available on nitrogen by an S(N)1 pathway, and finally ring-closure occurred. The intramolecular cyclization of APM determined by this microscopic FT-IR/DSC system was found to follow zero-order kinetics after a brief induction period. The bond cleavage energy (259.38 kJ/mol) of thermolysis for the leaving group of -OCH(3), the bond conversion energy (328.88 kJ/mol) for the amide II NH band to DKP NH band, and the CN bond formation energy (326.93 kJ/mol) of cyclization for the DKP in the APM molecule were also calculated from the Arrhenius equation. The total activation energy of the DKP formation via intramolecular cyclization was 261.33 kJ/mol, calculated by the above summation of the bond energy of cleavage, conversion, and formation, which was near to the value determined by the DSC or TGA method. This indicates that the microscopic FT-IR/DSC system is useful as a potential tool not only to investigate the degradation mechanism of drugs in the solid state but also to directly predict the bond energy of the reaction.

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The structural changes in the lipid of the excised skin of nude mice and the porcine stratum corneum was investigated by in vitro treatment with vitamin C, oleic acid, or DMSO. The CH 2 stretching vibrational peaks of lipid near 2920 cm -1 (asymmetric) and 2850 cm -1 (symmetric) shifted to higher wavenumber due to the lipid-disorder after in vitro treatment with above enhancers. The spectral shift of the asymmetric CH2 band was more sensitive than that of the symmetric CH2 band. The higher wavenumber of CH2 stretching bands decreased gradually to the lower region after co-treatment or posttreatment with pyrrolidone carboxylate sodium (PCA Na). Such a decrease was dependent on the PCA N a concentration and the time of treatment. The higher the concentration of PCA Na used, the lower value of the permeability coefficient of vitanIin C through the excised skin and the downward spectral shift of asymmetric CH2 band were obtained. When PCA Na coexisted with vitanIin C in the cell donor compartment, a competitive effect between PCA Na and vitanIin C was found. The oleic acid was supposed to directly insert it into the lipid structure to form a rigid structure, leading to larger spectral shift of both stretching bands but lesser restoring ability after PCA Na treatment. However, DMSO only displaces water from the lipid head groups and protein domain of skin to indirectly loosen the lipid structure, resulting in lesser spectral shift of the CH2 stretching bands to higher region, which was easier and better restoration after PCA Na application. The PCA Na enabled to restore the disordered lipid structure to order state might be attributed to PCA Na previously penetrated into skin and then absorbed water to directly or indirectly rearrange the disordered lipid bilayer structure.

Transformation of the secondary conformational structure of the human lens capsule after traumatic lens subluxation in a patient was investigated by Fourier transform infrared (FT-IR) microscopic spectrometry. The result was compared with the IR spectra of type IV collagen in crystalline state, solid film and aqueous solution and those of the excised and dried lens capsule under compression or treated with ethyl alcohol. The results indicate that the IR spectra of the intact human lens capsule after traumatic lens subluxation were the same as those of the rabbit lens capsule, except in the 1,100–1,000 cm^––1 proteoglycan region, but were different from those of type IV collagen aqueous solution at the amide I and II bands and the proteoglycan region, although type IV collagen is a predominant component of lens capsule. Two new peaks at 1,054 and 1,023 cm^––1 appeared on the IR spectra of the intact human lens capsule and on those of type IV collagen in crystalline state and solid film after compression but not in normal rabbit lens capsule and native type IV collagen. It was also found that all the IR spectra of the excised and dried lens capsule were similar to those of native type IV collagen in crystalline state and solid film. When pressure was applied on the excised and dried lens capsule, the directly compressed sample without KBr disks exhibited the same IR spectra as the original dried lens capsule did without treatment, but the sample compressed within KBr disks resulted in the deformation of the IR spectra at the amide I and II bands, and a new peak at 1,051 cm^––1 appeared in this proteoglycan region, suggesting that the pressure applied was retained in the compressed sample. The impact of pressure seemed to be significantly related to the IR spectral change in the proteoglycan region of the intact human lens capsule after traumatic lens subluxation. The IR spectra of the dried lens capsule pretreated with ethyl alcohol were found to change at the amide I and II bands.