Injectable hyaluronic acid-tyramine hydrogels for the treatment of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disease caused by inflammation of the synovial membrane, leading in turn to articular cartilage destruction. In this work, injectable tyramine modified hyaluronic acid (HA-Tyr) hydrogels were developed for the treatment of RA. HA-Tyr conjugate was synthesized by amide bond formation between carboxyl groups of HA and amine groups of tyramine. Then, HA-Tyr hydrogels were prepared by radical crosslinking reaction using H(2)O(2) and horse-radish peroxidase. Intra-articular injection of HA-Tyr hydrogels encapsulating dexamethasone (DMT) as a model drug resulted in successful treatment of RA with reduced interlukine-6, prostaglandin E2 and four types of cytokine levels in collagen-induced arthritis animal models. Histological analysis with hematoxylin and eosin (H&E) staining also confirmed the therapeutic effect of injectable HA-Tyr hydrogels with DMT. Taken together, the injectable HA-Tyr hydrogels were thought suitable to be developed as a therapeutically effective drug carrier for the treatment of RA.

Impact of helical computed tomography in clinically evident appendicitis.

OBJECTIVES: To determine the utility of multidetector computed tomography (MDCT) in patients with clinically evident acute appendicitis and to compare the test characteristics of overall clinical impression, Alvarado scores, and MDCT in suspected appendicitis. METHODS: A prospective observational cohort study was conducted in two urban emergency departments (ED). Consecutive patients with suspected acute appendicitis were clinically evaluated by an emergency physician who was asked to determine whether appendicitis was clinically evident or not. Elements of the Alvarado scores were collected and all patients then underwent MDCT and a decision to operate, observe, or discharge the patients was made by a surgeon. The final diagnosis was based on surgical pathology or clinical follow-up. The test characteristics of clinical impression, Alvarado scores and MDCT were then calculated and the rates at which acute appendicitis was falsely diagnosed based on clinical impression and MDCT were compared using McNemar's test. RESULTS: Of 157 study patients, 71 were considered to have clinically evident appendicitis before MDCT and 91 had findings of acute appendicitis on MDCT. 19 of the 71 patients with clinically evident appendicitis did not have appendicitis. 14 of 52 patients with an Alvarado score > or = 8 also did not have appendicitis. Three of 91 patients with acute appendicitis based on MDCT did not have appendicitis. The specificities of clinical impression and Alvarado score > or = 8 were 71.6% and 79.1%, respectively, and these were significantly lower than that of MDCT (95.5%, p<0.05). CONCLUSION: The performance of abdominal MDCT in patients with a high degree of clinical suspicion for acute appendicitis reduces the number of false positives and has the potential to reduce negative appendectomies.

Production of poly(3-hydroxybutyrate) by high cell density fed-batch culture of Alcaligenes eutrophus with phospate limitation.

High cell density fed-batch fermentation of Alcaligenes eutrophus was carried out for the production of poly(3-hydroxybutyrate) (PHB) in a 60-L fermentor. During the fermentation, pH was controlled with NH(4)OH solution and PHB accumulation was induced by phosphate limitation instead of nitrogen limitation. The glucose feeding was controlled by monitoring dissolved oxygen (DO) concentration and glucose concentration in the culture broth. The glucose concentration fluctuated within the range of 0-20 g/L. We have investigated the effect of initial phosphate concentration on the PHB production when the initial volume was fixed. Using an initial phosphate concentration of 5.5 g/L, the fed-batch fermentation resulted in a final cell concentration of 281 g/L, a PHB concentration of 232 g/L, and a PHB productivity of 3.14 g/L . h, which are the highest values ever reported to date. In this case, PHB content, cell yield from glucose, and PHB yield from glucose were 80, 0.46, and 0.38% (w/w), respectively.

Recovery and characterization of poly(3-hydroxybutyric acid) synthesized in Alcaligenes eutrophus and recombinant Escherichia coli.

We studied recovery of poly(3-hydroxybutyric acid) (PHB) from Alcaligenes eutrophus and a recombinant Escherichia coli strain harboring the A. eutrophus poly(3-hydroxyalkanoic acid) biosynthesis genes. The amount of PHB degraded to a lower-molecular-weight compound in A. eutrophus during the recovery process was significant when sodium hypochlorite was used, but the amount degraded in the recombinant E. coli strain was negligible. However, there was no difference between the two microorganisms in the patterns of molecular weight change when PHB was recovered by using dispersions of a sodium hypochlorite solution and chloroform. To understand these findings, we examined purified PHB and lyophilized cells containing PHB by using a differential scanning calorimeter, a thermogravimetric analyzer, and nuclear magnetic resonance. The results of our analysis of lyophilized whole cells containing PHB with the differential scanning calorimeter suggested that the PHB granules in the recombinant E. coli strain were crystalline, while most of the PHB in A. eutrophus was in a mobile amorphous state. The stability of the native PHB in the recombinant E. coli strain during sodium hypochlorite treatment seemed to be due to its crystalline morphology. In addition, as determined by the thermogravimetric analyzer study, lyophilized cell powder of the recombinant E. coli strain containing PHB exhibited greater thermal stability than purified PHB obtained by chloroform extraction. The PHB preparations extracted from the two microorganisms had identical polymer properties.

Optimization of microbial poly(3-hydroxybutyrate) recover using dispersions of sodium hypochlorite solution and chloroform.

Optimization was carried out for the recovery of microbiol poly(3-hydroxybutyrate) (PHB) from Alcaligenes eutrophus. This process involved the use of a dispersion made of sodium hypochlorite solution and chloroform. The dispersion enabled us to take advantage of both differential digestion by hypochlorite and solvent extraction by chloroform. The PHB recovery (%) from cell powder was maximized using a 30% hypochlorite concentration, a 90-min treatment time, and a 1:1 (v/v) chloroform-to-aqueous-phase ratio. Under these optimal conditions, the recovery was about 91% and the purity of recovered PHB was higher than 97%. The number average molecular weight, M(n) of recovered PHB was about 300,000 and the weight average molecular weight M(w) was about 1,020,000, compared to the original M(n) of 530,000 and M(w) of 1,272,000. The moderate decrease in both M(n) and M(w) might be ascribed to the shielding effect of chloroform. In addition, the relatively small decrease in M(w) probably resulted from the loss of short PHB chains which might be water soluble. The crystallinity of recovered PHB was in the range of 60 to 65%although a slightly higher crystallinity was observed when the dispersion was used. (c) 1994 John Wiley & Sons, Inc.

Origin and phylogeny of Guinea yams as revealed by RFLP analysis of chloroplast DNA and nuclear ribosomal DNA.

The origin and phylogeny of the Guinea yams, consisting of the white yam (Dioscorea rotundata Poir.) and the yellow yam (D. cayenensis Lamk.), has been investigated. Fourteen cultivars of Guinea yams were sampled with 12 accessions from seven wild yam species. A total of 26 accessions were surveyed for restriction fragment length polymorphisms (RFLP) in chloroplast DNA (cpDNA) and nuclear ribosomal DNA (rDNA) using seven restriction endonucleases and various heterologous probes. Chloroplast DNA probes covering 80% of the total chloroplast genome revealed nine restriction site changes and one length mutation among the cpDNAs of Guinea yams and their wild relatives. The estimated numbers of nucleotide substitutions per site (d) among these cpDNAs were very low (0.0005-0.0027), indicating a rather recent divergence of this group. On the basis of these ten mutations, five chloroplast genome types (A-E) were recognized. It was revealed that two cultivated species (D. rotundata and D. cayenensis) display the same chloroplast genome type, type A, as the three wild species D. praehensilis, D. liebrechtsiana and D. abyssinica. Chloroplast genome types B, C, D and E were found in D. minutiflora, D. burkilliana, D. smilacifolia and D. togoensis, respectively. Maximum parsimony analysis produced a hypothetical phylogeny of three primary lineages among cpDNAs of Guinea yams and their relatives: the genome type A lineage, the genome type B lineage and one lineage including genome types C, D and E.Using rDNA clones of rice and taro as probes, we detected ribosomal DNA variation, presumably at the intergenic spacer region, in Guinea yams and their wild relatives. The survey of rDNA together with that of cpDNA indicates that D. rotundata (white yam) was domesticated from either D. abyssinica, D. liebrechtsiana or D. praehensilis or their hybrid, and that D. cayenensis (yellow yam) is derived from hybridization between a male plant of either D. burkilliana, D. minutiflora or D. smilacifolia and a female plant of either D. rotundata, D. abyssinica, D. liebrechtsiana or D. praehensilis. We propose that the previous nomenclature of white yam should be retained, D. rotundata Poir. nomen nudum, and that yellow yam should be treated as a variety of D. rotundata, denoted as D. rotundata var. x 'cayenensis'.

Tetraploids, triploids, and 2n pollen from diploid interspecific crosses with cassava.

Interspecific crosses of five cultivated cassava varieties (2n=36) were made with two related Manihot species, M. epruinosa (2n=36) and M. glaziovii (2n=36). From these diploid interspecific crosses, four spontaneous tetraploids (2n=4x=72) and two triploids (2n=3x=54) were isolated for the first time in cassava. Occurrence of relatively high frequencies (0.1%-35.6%) of 2n pollen and of apomixis seems to be associated with sexual polyploidization. The tetraploids and triploids were very vigorous and one of the tetraploids performed as well as the best variety in uniform yield trials conducted in Nigeria. These spontaneous polypoloids provide greater genetic variation and offer an opportunity to breed radically new cassava varieties. Approaches for isolating and utilizing the polyploid cassava clones for varietal and population improvement are discussed.