Cyanide-induced alterations to the biophysical conformations of the isolated fish liver

The purpose of this study is to examine the applicability of an infared spectroscopic methodology for the study of an environmental problem. The effect of cyanide concentrations on the biophysical conformation of the fish liver homogenate was determined by using an attenuated total reflectance (ATR)/Fourier transform infrared (FT-IR) microspectroscopy. Alive male model fish, Tilapia Zillii, was used. The liver from fish was isolated and homogenized in pH 8.0 Tris buffer solution. The results indicate that the IR peak intensity increased markedly in the C-H stretching range (3000-2800 cm-1), ester C = O stretching of lipids (1743 cm-1) and carbohydrate bands (1195-950 cm-1), but decreased in the amide I at 1649 cm-1 and the free asymmetric stretching band of phosphate at 1261 cm-1 with the increase of KCN concentrations. The marked release of hepatic enzymes and glutathione into homogenate induced by cyanide might account for the higher IR spectral peak intensity of fish liver tissue after treatment with KCN. The cyanide was also found to induce the protein structure of fish liver homogenate from alpha-helical conformation to beta-conformation.

Surgical treatment for concomitant fractures of the femoral neck and diaphysis: a treatment protocol

Concomitant ipsilateral femoral shaft and neck fractures are difficult to treat. The standard protocol in our hospital is plates for diaphyseal fractures and lag screws or dynamic hip screws (DHS) fixations for the femoral neck fractures. We treated 21 patients with these complex fractures between 1988 and 1998 with this protocol. All patients were injured from high-energy trauma. There were 15 males and 6 females with an average age of 44 years. The average follow-up period is 50 months. All except one patient united well. During the follow-up period, neither non-union of the femoral neck fracture nor osteonecrosis of the femoral head was noted. There was also no malunion. There were twenty good results and one poor functional result. We conclude that plate on the shaft and sliding hip screws or separate screws in the hip are a reliable method for concomitant ipsilateral femoral neck and shaft fractures.

Reaction kinetics of solid-state cyclization of enalapril maleate investigated by isothermal FT-IR microscopic system

To investigate the reaction kinetics of the solid-state degradation process of enalapril maleate, a Fourier transform infrared microspectroscope equipped with thermal analyzer (thermal FT-IR microscopic system) was used. The isothermal stability study was conducted at 120-130 degrees C for 1-2 h and changes in the three-dimensional plots of the IR spectra of enalapril maleate with respect to heating time were observed. The study indicates that the bands at 1649, 1728, and 1751 cm(-1) assigned to intact enalapril maleate gradually reduced in peak intensity with heating time. However, the peak intensities at 1672 and 1738 cm(-1) (due to enalapril diketopiperazine (DKP) formation) and at 3250 cm(-1) (corresponding to water formation) gradually increased with heating time. The solid-state diketopiperazine formation and the degradation process of enalapril maleate via intramolecular cyclization were found to be simultaneous. The isothermal decomposition curves were sigmoidal and were characterized by induction and acceleration periods, indicating the presence of autocatalytic solid-state decompositions. Moreover, the power-law equation (n = 1/4) was found to provide the best fit to the kinetics of decomposition. This isothermal FT-IR microscopic system was easily used to investigate the degradation of enalapril maleate and the concomitant formation of DKP. The solid-state reaction of enalapril maleate required an activation energy of 195+/-12 kJ/mol to undergo the processes of decomposition and intramolecular cyclization.

Continuous UVB irradiation to modify the biophysical properties and protein conformation of rat skin

In order to determine the continuous irradiation effects of UVB on the skin of live Sprague Dawley (SD) rats, the changes in biophysical properties and protein conformation of the skin were studied. The continuous UVB irradiation affecting the water content, skin color and protein structure of the rat skin was investigated by using a skin surface hygrometer, a Chroma meter and an attenuated total reflection (ATR)/Fourier transform infrared (FT-IR) spectroscopy. Test areas on the dorsal skin were continuously irradiated with 600 +/- 10 microW/cm2 UVB for 56 h. Part of the dorsal skin was covered with a bandage as a non-irradiated control. The results indicated that the water content of the irradiated skin decreased with UVB irradiation, but the non-irradiated control skin exhibited a higher level of water content. The decrease in the skin's water-binding capacity from cracks induced by continuous UVB irradiation, and the occlusive dressing of the non-irradiated skin to prevent water loss and form full hydration might be responsible for the results. The decrease of L* value and the increase in a*, b* and delta E values in the skin color parameters with UVB irradiation indicates an incremental darkening of the skin and a marked increase in erythema. However, there was no significant change in skin color for the non-irradiated control skin. A slight modification of the protein secondary structure in the skin after continuous UVB irradiation was also evidenced by transforming the alpha-helix structure into a beta-sheet structure after long-term continuous UVB irradiation. Continuous UVB irradiation of SD rat skin may decrease the skin's water-binding capacity, cause darkening, increase erythema and modify the protein secondary structure of the skin.

Presence of Epstein-Barr virus latent membrane protein 1 gene in the nasopharyngeal swabs from patients with nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is the most common head and neck malignancy in southeastern China and Taiwan. Early detection of the local disease followed immediately by proper treatment is essential to increase the cure and survival rates. Because every NPC tumor cell carries Epstein-Barr Virus (EBV) genomes, detection of EBV genomic DNA such as latent membrane protein 1 gene (LMP1) might indicate the presence of NPC. We developed a simple and noninvasive technique of nasopharyngeal swabbing to acquire nasopharyngeal cells for detecting the presence of EBV genome. The aim of this study was to investigate the feasibility and reliability of this technique.

METHODS

We collected nasopharyngeal cells by means of a nasopharyngeal swabbing technique and detected the presence of EBV LMP1 with polymerase chain reaction (PCR). Thirty-eight swab specimens were obtained from patients with NPC who were newly diagnosed or were just beginning radiotherapy. Two groups of control subjects were recruited, including 20 patients with other head and neck cancers and eight family members of the NPC patients. An additional group of 65 NPC patients were enrolled in the course of regular follow-up after definitive radiotherapy.

RESULTS

All of the samples yielded sufficient DNA for PCR amplification. Thirty-six of 38 NPC swab samples were positive for EBV LMP1, and all the control subjects had swab sample results negative for EBV. All five patients with suspected local recurrence exhibited positive EBV test results.

CONCLUSIONS

Demonstration of EBV LMP1 in the nasopharyngeal swab specimens detected NPC with a sensitivity of 94.7% and specificity of 100%. This study confirms the reliability and feasibility of nasopharyngeal swab in the predicting and screening of NPC.

Quantitative analysis of bending efficiency in photonic-crystal waveguide bends at lambda = 1.55 mum wavelengths

Based on a photonic-crystal slab structure, a 60 degrees photonic-crystal waveguide bend is successfully fabricated. Its bending efficiency within the photonic bandgap is measured, and near 100% efficiency is observed at certain frequencies near the valence band edge. The bending radius is ~1mum at a wavelength of lambda~1.55mum . The measured eta spectrum also agrees well with a finite-difference time-domain simulation.

Simvastatin treatment on postprandial hypertriglyceridemia in type 2 diabetes mellitus patients with combined hyperlipidemia

Recent studies have shown that statins are effective in reducing fasting low-density lipoprotein-cholesterol (LDL-C) and triglyceride levels. However, it remains unknown if treatment with statins also lowers daily postprandial triglyceride concentrations, which may promote atherogenesis in type 2 diabetes subjects. Forty-one subjects with type 2 diabetes and combined hyperlipidemia who had stable glycemic control were randomly assigned to take simvastatin 20 mg (n = 27) or a placebo (n = 14) once daily for 12 weeks. The medication dosage was doubled after 4 weeks if a subject's LDL-C was not less than 130 mg/dL. Among these participants, 24 subjects (15 on simvastatin and 9 on placebo) agreed to take a meal tolerance test with isocaloric mixed meals (carbohydrate, 52%; fat, 33%, and protein, 15% of the daily caloric intake) and daytime hourly blood sampling from 8 AM to 4 PM. Simvastatin treatment reduced the fasting total cholesterol level from 237 +/- 5 to 178 +/- 6 mg/dL (-25%), the LDL cholesterol level from 150 +/- 6 to 87 +/- 5 mg/dL (-40%), and raised high-density lipoprotein-cholesterol (HDL-C) level from 36 +/- 2 to 40 +/- 2 mg/dL (+11%) (all P <.001). Fasting and daily ambient triglyceride concentrations from 8 AM to 4 PM decreased significantly in response to simvastatin administration (P <.001), but not to the placebo (P =.305). Simvastatin treatment not only decreased total cholesterol and LDL-C levels and increased HDL-C levels effectively, it also decreased fasting, as well as daily postprandial triglyceride concentrations, but had no effect on glycemic control in type 2 diabetes subjects with combined hyperlipidemia.

Hepatoprotective effects of Arctium lappa on carbon tetrachloride- and acetaminophen-induced liver damage

The root of Arctium lappa Linne (A. lappa) (Compositae), a perennial herb, has been cultivated for a long time as a popular vegetable. In order to investigate the hepatoprotective effects of A. lappa, male ICR mice were injected with carbon tetrachloride (CCl4, 32 microl/kg, i.p.) or acetaminophen (600 mg/kg, i.p.). A. lappa suppressed the SGOT and SGPT elevations induced by CCl4 or acetaminophen in a dose-dependent manner and alleviated the severity of liver damage based on histopathological observations. In an attempt to elucidate the possible mechanism(s) of this hepatoprotective effect, glutathione (GSH), cytochrome P-450 (P-450) and malondialdehyde (MDA) contents were studied. A. lappa reversed the decrease in GSH and P-450 induced by CCl4 and acetaminophen. It was also found that A. lappa decreased the malondialdehyde (MDA) content in CCl4 or acetaminophen-intoxicated mice. From these results, it was suggested that A. lappa could protect the liver cells from CCl4 or acetaminophen-induced liver damages, perhaps by its antioxidative effect on hepatocytes, hence eliminating the deleterious effects of toxic metabolites from CCl4 or acetaminophen.

Micronized ethylcellulose used for designing a directly compressed time-controlled disintegration tablet

Ethylcellulose (EC) of varying particle sizes has been used as an outer coating layer to design a novel dry-coated tablet with time-controlled drug release. This dry-coated tablet, containing a core tablet of sodium diclofenac and an outer coating layer of EC, was prepared by direct compression. The drug release from dry-coated tablet exhibited an initial lag period that was dependent on the particle size of the EC powder, followed by a stage of rapid drug release. The smaller the EC particle size used the longer the lag time obtained, suggesting the particle size of EC powder could modulate the timing of drug release from such a dry-coated tablet. The period of the lag time for sodium diclofenac released from dry-coated tablets was correlated with the penetration distance of the solvent into dry-coated tablet by an in vitro dye penetration study. The densest packing of EC powders appeared on the upper and lower surfaces of dry-coated tablet after compression, resulting in a tight structure yielding a slower penetration of the solvent. Whereas loose packing of EC powders occurred in the middle of the lateral surface of dry-coated tablet, this loosely packed surface readily allowed solvent penetration and that finally caused the splitting of tablet shell into two halves in the dissolution medium. The results suggest that these dry-coated tablets prepared with different particle sizes of EC powder as an outer coating layer might offer a desirable release profile for drug delivery at the predetermined times and/or sites.

Temperature-induced conformational changes in amyloid beta(1-40) peptide investigated by simultaneous FT-IR microspectroscopy with thermal system

Temperature-dependent secondary structures of the amyloid beta(1-40) peptide in the solid state were studied by simultaneous Fourier transform infrared/differential scanning calorimetry (FT-IR/DSC) microspectroscopic system with the heating-cooling-reheating cycle. The result indicates that a thermal transition temperature at 45 degrees C was easily obtained from the three-dimensional plot of the transmission FT-IR spectra as a function of temperature. Furthermore, the thermal-dependent conformational transformations, due to denaturation and aggregation, of solid amyloid beta(1-40) were mainly evidenced by reducing the compositions from 37 to 20-24% for alpha-helical and random coil structures but increasing the components from 27 to 45% for intermolecular beta-sheet structures. Thermal-irreversible behavior and a poor thermal stability of solid amyloid beta(1-40) were also observed from the poor restoration of the secondary conformational changes in the heated sample.

Acute open perilunate dislocation--a case report

A rare case of acute open dorsal perilunate dislocation of the left hand was encountered in a 30-year-old man with exposure of the lunate and distal radius. No other combined injury was identified except open dislocation and chip avulsion fracture of triquetrum. Open reduction was performed through a dorsal approach after debridement. Such a severe injury, to our knowledge, has not been reported previously.

Extensor digitorum brevis rotational muscle flap for lower leg and ankle coverage

BACKGROUND

Soft tissue reconstruction around the ankle has been a challenging problem. This article reports our experience using the extensor digitorum brevis muscle flap; some technical variations are discussed.

METHODS

The extensor digitorum brevis muscle flap is vascularized by the well-defined lateral tarsal artery, a branch of the dorsalis pedis artery originating at the level of the inferior extensor retinaculum. This flap was used for coverage of soft tissue defects in the lower leg and the ankle in 10 patients with various injuries.

RESULTS

All flaps survived completely. Complications included delayed healing of donor skin in two cases. Flap elevation was possible even in the traumatized donor foot.

CONCLUSION

The advantages of this flap include constant and reliable blood supply, easy and rapid flap dissection, adequate bulk, and one-stage procedure. However, disadvantages include the small size of the flap and the sacrifice of the dorsalis pedis artery.

Hairy cell leukemia in Hong Kong Chinese: a 12-year retrospective survey

BACKGROUND

Hairy cell leukemia (HCL) is a unique chronic B cell lymphoproliferative disease (B-LPD), with distinct clinical and pathological features, and excellent treatment response to 2-chlorodeoxyadenosine (2-CDA) and pentostatin. There have been few reports of HCL from oriental countries.

PATIENTS AND METHODS

A retrospective survey of HCL in six major hematology units in Hong Kong over a 12-year period.

RESULTS

There were 18 cases of HCL identified. Most patients presented with fever, splenomegaly and monocytopenia. Lymphadenopathy was present in three patients, and open biopsy revealed tuberculosis infection in two cases. Seven cases received interferon and 12 cases received 2-CDA. Four patients died from bronchogenic carcinoma, cerebral vascular accident, fulminant hepatitis B virus reactivation and malignant melanoma. The remaining 14 patients are in clinical remission at a median of 6 years' follow-up; two are also surviving from second malignancies (thyroid papillary carcinoma and renal cell carcinoma).

CONCLUSIONS

Parallel to the low incidence of B-LPD in Chinese, the incidence of HCL (0.035/100000 population per year) is much lower than in Western series. Other clinical features such as male dominance, clinical presentation, response to 2-CDA treatment, and association with second malignancy are similar to Western reports. However, two common complications in the Chinese population are the fulminant reactivation of hepatitis B infection and disseminated tuberculosis infection.

Thermal-Dependent dehydration process and intramolecular cyclization of lisinopril dihydrate in the solid state

The pathway of dehydration and intramolecular cyclization of lisinopril dihydrate in the solid state was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and a combination of thermal analyzer with Fourier transform infrared microspectroscopy (thermal FT-IR microscopic system). The results indicate that the dehydration from the solid-state lisinopril dihydrate had a two-step process from dihydrate to monohydrate at 76 degrees C and then from monohydrate to anhydrate at 99-101 approximately C, which could be clearly observed from the above three methods. Only the thermal FT-IR microscopic system could give vital information on diketopiperazine (DKP) formation via intramolecular cyclization in anhydrous lisinopril. A new peak at 1670 cm(-1) assigned to the carbonyl band of DKP formation was clearly evidenced. The water of reaction byproduct was liberated at a temperature >157 degrees C and appeared on the IR spectra near 3200-3400 cm(-1). Moreover, the peak at 1574 cm(-1) assigned to carboxylate shifted to 1552 cm(-1) due to the DKP formation. The peak at 1670 cm(-1) related to the DKP formation changed slightly in intensity from 147 degrees C and significantly near 157 degrees C. DSC and TGA methods were poor for use in supplying information on DKP formation in lisinopril. The thermal FT-IR microscopic system is useful from the view point that it can quickly and directly show the solid-state stability of drug.

Percutaneous release of abductor pollicis brevis muscle fibrosis in a bowler--a case report

The authors reported a patient with abductor pollicis brevis muscle fibrosis of the right thumb, stemming from a bowling injury that had occurred 6 years previously. At that time in the acute stage, a Chinese bonesetter treated the injury using manipulation, massage and herbal drugs. Abduction contracture of the patient's right thumb developed. She began to experience chronic pain at dorsal side of her right thumb and discovered that she could not move her thumb into a retro position. When she came into our hospital, physical examination revealed an abduction contracture of patient's right thumb, the angle of separation was 60 degrees, and the angle of circumduction was fixed at 90 degrees. In addition, a fibrotic band was palpable in abductor pollicis brevis muscle. The patient responded well to percutaneous release and physical therapy. As far as we know, this is an unusual case, which has not been reported before.

Differentiation of hair growth cycle from scalp hair roots for the diagnosis of glucose-6-phosphate dehydrogenase deficiency in neonates

Hair analysis can be used as a screening tool in the diagnosis of genetic diseases. The scalp hair roots of 67 normal neonates and 39 neonates with glucose-6-phosphate dehydrogenase (G6PD) deficiency were analysed using Fourier transform infrared (FT-IR) microspectroscopy to differentiate the stages of the hair growth cycle and to diagnose the genetic disorder on the basis of spectral differences. We have demonstrated that FT-IR microspectroscopy is a rapid and effective noninvasive diagnostic method to differentiate scalp hair roots of normal neonates into the anagen, catagen or telogen phases of the hair growth cycle, using IR spectral differences within the 3000-2800 cm(-1) region and the IR peak area ratio of 2854 cm(-1)/2873 cm(-1) or 1084 cm(-1)/amide II band (p<0.001). Moreover, G6PD-deficient neonates could be accurately diagnosed from telogen phase hair roots owing to significant differences in IR peak area ratios of 2854 cm(-1)/2873(-1) or 1084 cm(-1)/amide II band compared to normal values in healthy neonates. The result suggests that the application of FT-IR microspectroscopy may be capable not only of differentiating the hair growth cycle into anagen, categen or telogen phases but also of detecting G6PD deficiency. Hair root analysis promises to be a useful complement to serum and urine analysis in the diagnosis of genetic diseases.

Effect of skin-penetrating enhancers on the thermophysical properties of cholesteryl oleyl carbonate embedded in a thermo-responsive membrane

The effect of skin-penetrating enhancers such as propylene glycol (PG), Azone and ethanol on the thermophysical properties of cholesteryl oleyl carbonate (COC) was investigated using differential scanning colorimetry (DSC) and microscopic Fourier-transform infrared (FT-IR) spectroscopy. The results indicate that PG did not influence the DSC thermograms and IR spectra of COC in the different ratios of COC and PG mixture; whereas Azone interacted with COC not only to lower the semectic-cholesteric phase transition temperature of COC but also to induce a new IR spectral peak at 1653 cm(-1) which shifted from the carbonyl stretching band (1636 cm(-1)) of Azone. Ethanol did not interact with COC, but it influenced the IR spectral peak intensity of COC at 1253 cm(-1). The peak intensity at 1253 cm(-1) gradually rose with the time of ethanol evaporation and was similar to that of the temperature effect. The solubility parameter was also used to explain the miscibility and interaction between COC and PG, Azone or ethanol.

Dome corrective osteotomy for cubitus varus deformity

Between 1994 and 1998, 15 patients had corrective dome-shaped osteotomy of the humerus for posttraumatic cubitus varus deformity. Thirteen patients had surgery before puberty and two patients had surgery after puberty. In the prepuberty group, all the osteotomies were done by a posterior approach with triceps muscle splitting, and cross pins were used to fix the osteotomy. In the postpuberty group, the osteotomies were done by a posterior approach with olecranon osteotomy, and reconstructive plates were used for fixation. The average followup was 2 years and 4 months. Preoperative carrying angle ranged from 19 degrees to 31 degrees varus (average, 26.2 degrees) and postoperative carrying angle ranged from 7 degrees to 15 degrees valgus (average, 10.7 degrees). No loss of correction was observed and all osteotomies united. The preoperative and postoperative differences of the lateral condylar prominence index ranged from -67% to +6% (average, -30.1%). After reviewing these cases, a dome-shaped osteotomy was found to have the following advantages for correction of cubitus varus deformity: the osteotomy site is more stable than a lateral closing wedge osteotomy for maintaining the correction obtained; the domed osteotomy avoids having the lateral condyle becoming prominent; and the posterior scar is more cosmetically acceptable than the lateral scar in the lateral closing wedge osteotomy.

Ipsilateral fractures of the femoral neck and shaft

Ipsilateral femoral shaft and neck fractures are difficult to treat. From 1989 to 1998, we treated 18 patients with these complex fractures. There were 14 male and 4 female with an average age of 40 years. Most resulted from high-energy trauma. The average follow-up period is 41 months. All but one of the fractures united well. The mean time to union is 5.2+/-2.3 months in the diaphysis and 4.16+/-2 months in the neck. No cases of the femoral neck fracture or osteonecrosis of the femoral head were observed during the follow-up period. Fourteen cases were treated with a standard protocol of plates for diaphyseal fractures and lag screws or dynamic hip screws (DHS) fixations for the femoral neck fractures. There were 13 good and 1 fair functional results. Two neglected neck fractures were treated with interlocking nailing for diaphyseal fracture with fair results. We conclude that a plate on the shaft and sliding hip screws or separate screws in the hip is a reliable method for ipsilateral femoral neck and shaft fractures.

Three-dimensional control of light in a two-dimensional photonic crystal slab

Optoelectronic devices are increasingly important in communication and information technology. To achieve the necessary manipulation of light (which carries information in optoelectronic devices), considerable efforts are directed at the development of photonic crystals--periodic dielectric materials that have so-called photonic bandgaps, which prohibit the propagation of photons having energies within the bandgap region. Straightforward application of the bandgap concept is generally thought to require three-dimensional (3D) photonic crystals; their two-dimensional (2D) counterparts confine light in the crystal plane, but not in the perpendicular z direction, which inevitably leads to diffraction losses. Nonetheless, 2D photonic crystals still attract interest because they are potentially more amenable to fabrication by existing techniques and diffraction losses need not seriously impair utility. Here we report the fabrication of a waveguide-coupled photonic crystal slab (essentially a free-standing 2D photonic crystal) with a strong 2D bandgap at wavelengths of about 1.5 microm, yet which is capable of fully controlling light in all three dimensions. These features confirm theoretical calculations on the possibility of achieving 3D light control using 2D bandgaps, with index guiding providing control in the third dimension, and raise the prospect of being able to realize unusual photonic-crystal devices, such as thresholdless lasers.

Simultaneous formation and detection of the reaction product of solid-state aspartame sweetener by FT-IR/DSC microscopic system

The solid-state stability of aspartame hemihydrate (APM) sweetener during thermal treatment is important information for the food industry. The present study uses the novel technique of Fourier transform infrared microspectroscopy equipped with differential scanning calorimetry (FT-IR/DSC microscopic system) to accelerate and determine simultaneously the thermal-dependent impurity formation of solid-state APM. The results indicate a dramatic change in IR spectra from 50, 110 or 153 degrees C, which was respectively attributed to the onset temperature of water evaporation, dehydration and cyclization processes. It is suggested that the processes of dehydration and intramolecular cyclization occurred in the solid-state APM during the heating process. As an impurity, 3-carboxymethyl-6-benzyl-2,5-diketopiperazine (DKP) degraded from solid state APM via intramolecular cyclization and liberation of methanol. This was evidenced by this novel FT-IR/DSC microscopic system in a one-step procedure.

Organic esters of plasticizers affecting the water absorption, adhesive property, glass transition temperature and plasticizer permanence of eudragit acrylic films

The materials used in film coating technology are very important tools for pharmaceutical applications. The effects of four organic esters used as plasticizers (triacetin, diethyl phthalate (DEP), dibutyl phthalate (DBP) and tributyl citrate (TBC)) on the water absorption behavior and adhesive property of Eudragit films and on the glass transition temperature (T(g)) and plasticizer permanence of Eudragit E film were investigated. The results indicate that the water absorption of these Eudragit films was dependent on the type of Eudragit polymers and plasticizers used. Eudragit E film plasticized with triacetin showed a slight water absorption, but when plasticized with DEP, DBP or TBC did not. All Eudragit RL films showed significant uptake of water, but Eudragit RS films exhibited a lesser degree of water absorption. The adhesion (tack value) of all Eudragit films was markedly increased when the concentration of plasticizer was greater than 25%. Eudragit E film exhibited a greater adhesiveness than the Eudragit RL or RS film, particularly with higher plasticizer concentration. Weight loss of the Eudragit E film plasticized with triacetin or DEP was more pronounced with aging, but when plasticized with DBP or TBC weight loss was not seen. The results indicate that TBC may be the best choice of plasticizer for Eudragit film, particularly for the Eudragit E film.

In vitro degradation and dissolution behaviours of microspheres prepared by three low molecular weight polyesters

Three low-molecular weight polyesters, poly(L-lactic acid) (PLA), copoly(lactic acid/glycolic acid) (PLGA) and poly(delta-valerolactone) (PV), were used to prepare water-soluble sodium diclofenac-loaded microspheres by using the oil-in-oil (o/o) emulsification-solvent evaporation method. Their micromeritic and physicochemical properties, and degradation and dissolution behaviours were determined in vitro. The results indicate that high encapsulation efficiency and better monodispersity might be achieved by the o/o emulsification-solvent evaporation method, depending on the amount of drug loading used. The slower evaporation of organic solvent from the system during microencapsulation seemed to modify the crystallinity of drug and polyester in the microspheres, determined by powder x-ray diffractometry and differential scanning calorimetry. The in vitro degradation rate of all the microspheres in pH7.4 phosphate buffer solution showed first-order kinetics and ranked in the order of PLGA > PLA > PV microspheres. Furthermore, the first-order release rate was also found in all the microspheres after an initial drug burst and ranked in the order of PLGA> PLA > PV microspheres, too. The relationship between degradation and dissolution behaviours of these microspheres is discussed.