Improving the stability of aptamers by chemical modification

Ever since the invention of SELEX (systematic evolution of ligands by exponential enrichment), there has been rapid development for aptamers over the last two decades, making them a promising approach in therapeutic applications as either drug candidates or diagnostic tools. For therapeutic purposes, a durable performance of aptamers in biofluids is required, which is, however, hampered by the lack of stability of most aptamers. Not only are the nucleic acid aptamers susceptible to nucleases, the peptide aptamers are also subjective to degradation by proteases. With the advancement of chemical biology, numerous attempts have been made to overcome this obstacle, many resulting in significant improvements in stability. In this review, chemical modifications to increase the stability of three main types of aptamers, DNA, RNA and peptide are comprehensively summarized. For nucleic acid aptamers, development of modified SELEX coupled with mutated polymerase is discussed, which is adaptive to a number of modifications in aptamers and in a large extent facilitates the research of aptamer-modifications. For peptide aptamers, approaches in molecular biology with introduction of stabilizing protein as well as the switch of scaffold protein are included, which may represent a future direction of chemical conjugations to aptamers.

Steam-pelleting and feed form of broiler diets based on three coarsely ground sorghums influences growth performance,nutrient utilisation, starch and nitrogen digestibility

Sorghum grains with red, white and yellow seed colours were coarsely ground and incorporated into nutritionally equivalent diets that were offered to broiler chicks in three feed forms. The diets were fed as mash or steam-pelleted at a conditioning temperature of 90°C and fed as intact pellets or ground back into mash as reground pellets. The effects of a 3 × 3 factorial array of dietary treatments offered to male chicks from 6 to 27 days post-hatch on growth performance, nutrient utilisation and apparent digestibility coefficients of starch and nitrogen (N) at the proximal jejunum, proximal ileum and distal ileum were determined. Feed form had a greater impact on the parameters assessed than did sorghum seed colour, but several interactions between these main effects were observed. Steam-pelleting diets reduced protein solubility and this was correlated with increased concentrations of disulfide bonds and decreased concentrations of free sulphydryl groups. Steam-pelleting diets significantly depressed N retention in broiler chicks and this reduction was appropriately correlated with concentrations of disulfide bonds and free sulphydryl groups and dietary protein solubility. While N retention was depressed, in a curious outcome, steam-pelleting diets did not compromise N digestibility along the small intestine. Steam-pelleting diets significantly increased starch digestibility coefficients in the proximal jejunum, with differing responses among the sorghums, but not in the two ileal levels. Phytate concentrations in the three sorghums were negatively correlated with N digestibility coefficients at the proximal jejunum and proximal ileum. The implications of the present feeding study in relation to the performance of broiler chickens offered steam-pelleted, sorghum-based diets are discussed.

Ethnoveterinary application of Morinda citrifolia fruit puree on a commercial heifer rearing facility with endemic salmonellosis

We have previously reported that Morinda citrifolia (noni) puree modulates neonatal calves developmental maturation of the innate and adaptive immune system. In this study, the effect of noni puree on respiratory and gastrointestinal (GI), health in preweaned dairy calves on a farm with endemic salmonellosis was examined. Two clinical trials were conducted whereby each trial evaluated one processing technique of noni puree. Trials 1 and 2 tested noni versions A and B, respectively. Puree analysis and trial methods were identical to each other, with the calf as the experimental unit. Calves were designated to 1 of 3 treatment groups in each trial and received either: 0, 15 or 30 mL every 12 hr of noni supplement for the first 3 weeks of life. Health scores, weaning age, weight gain from admission to weaning, and weaned by 6 weeks, were used as clinical endpoints for statistical analysis. In trial 1, calves supplemented with 15 mL noni puree of version A every 12 hr had a higher probability of being weaned by 6 weeks of age than control calves (P = 0.04). In trial 2, calves receiving 30 mL of version B every 12 hr had a 54.5% reduction in total medical treatments by 42 days of age when compared to controls (P = 0.02). There was a trend in reduced respiratory (61%), and GI (52%) medical treatments per calf when compared to controls (P = 0.06 and 0.08, respectively). There were no differences in weight gain or mortality for any treatment group in either trial.

Functional characterisation of a natural androgen receptor missense mutation (N771H) causing human androgen insensitivity syndrome

Androgen insensitivity syndrome (AIS) is an X-linked disorder due to mutations of androgen receptor (AR) gene. Various AR mutations have been identified, and the characterisation of these mutations greatly facilitates our understanding of AR structure-function. In this study, we have analysed an AR missense mutation (N771H) identified in patients with AIS. Functional analysis of the mutant AR was performed by in vitro mutagenesis-cotransfection assays. Compared to the wild-type AR, the dose-response curve of dihydrotestosterone-induced transactivation activity in the mutant AR was greatly shifted to the right and significantly decreased. However, the maximal efficacy of transactivation activity in the mutant AR was similar to that of the wild type. Receptor binding assay indicated that the mutant AR had an approximately 2.5-fold lower binding affinity to dihydrotestosterone compared to the wild type. Western blot analysis showed that the size and the expression level of mutant AR in transfected cells were comparable to the wild type. These data underscore the importance of asparagine at amino acid position 771 of human AR in normal ligand binding and normal receptor function, and a mutation at this position results in androgen insensitivity in affected subjects.

A prospective randomized study comparing open versus laparoscopy-assisted D2 radical gastrectomy in advanced gastric cancer

BACKGROUND

In recent years, many clinical studies have confirmed the value of laparoscopy-assisted gastrectomy (LAG) in gastric cancer surgery, especially in early stages. But the safety and oncologic adequacy of laparoscopy-assisted D2 radical gastrectomy for advanced gastric cancer are still in debate. We conducted a prospective randomized trial to compare open versus laparoscopy-assisted D2 radical gastrectomy in advanced gastric cancer.

METHODS

For this study, 123 patients who had been diagnosed endoscopically with gastric cancer were randomly assigned to either LAG (n = 61) or open gastrectomy (OG) (n = 62) which ran from March 2008 to December 2009. Clinical characteristics, operative findings, postoperative recovery, morbidity, pathological report and survival rate were compared. D2 lymph node dissection was performed in 49 patients in the LAG group and 47 patients in the OG group with advanced gastric cancer. We adopt sub-group analysis in this paper.

RESULTS

The clinical characteristics of patients in the LAG and OG groups who were in the advanced stage, included age, sex, BMI and concurrent illness, and their ECOG scores were well matched. Operative findings, postoperative recovery, morbidity, pathological findings including tumor location, depth of invasion, TNM stage, histological grade and surgical extension in the two groups were also similar. Compared to the OG group, the mean operating time was significantly longer for the LAG group (267.88 ± 54.284 min in the LAG group vs. 182.02 ± 41.016 min in the OG group, p = 6.383 × 10(-13)); the mean number of days when body temperature exceeded 37°C was significantly shorter in the LAG group (p = 6.34 × 10(-8)). There were no postoperative deaths in both the groups. The postoperative morbidity rate was 12.24% in the LAG group and 19.15% in the OG group with no significant difference (p = 0.357). However, pulmonary infection was observed more frequently in the OG group (p = 0.038). After a mean follow-up of 22.1354 months (from 4 to 36 months), 14 and 15 patients died of gastric cancer in the LAG and OG groups, respectively. Two and one patient died of nongastric cancer in the LAG and OG groups, respectively. The overall survival rates were 67.1% and 53.8% in the LAG and OG groups, respectively. The estimated mean survival time was 29.387 months in the LAG group and 28.978 months in the OG group. There was no statistically significant difference in the overall survival rate for patients in both groups - LAG and OG (log-rank test, p = 0.911, Tarone Ware test, p = 0.994, and Breslow test, p = 0. 961).

CONCLUSION

LAG with D2 lymph node dissection is a safe and feasible procedure with adequate lymphadenectomy, good curability and survival rate for the treatment of advanced gastric cancer.

The preventive effects of pulsed electromagnetic fields on diabetic bone loss in streptozotocin-treated rats

The present study was the first report demonstrating that pulsed electromagnetic field (PEMF) could partially prevent bone strength and architecture deterioration and improve the impaired bone formation in streptozotocin-induced diabetic rats. The findings indicated that PEMF might become a potential additive method for inhibiting diabetic osteopenia or osteoporosis.

INTRODUCTION

Diabetes mellitus (DM) can cause various musculoskeletal abnormalities. Optimal therapeutic methods for diabetic bone complication are still lacking. It is essential to develop more effective and safe therapeutic methods for diabetic bone disorders. Pulsed electromagnetic field (PEMF) as an alternative noninvasive method has proven to be effective for treating fracture healing and osteoporosis in non-diabetic conditions. However, the issue about the therapeutic effects of PEMF on diabetic bone complication has not been previously investigated.

METHODS

We herein systematically evaluated the preventive effects of PEMF on diabetic bone loss in streptozotocin-treated rats. Two similar experiments were conducted. In each experiment, 16 diabetic and eight non-diabetic rats were equally assigned to the control, DM, and DM + PEMF group. DM + PEMF group was subjected to daily 8-h PEMF exposure for 8 weeks.

RESULTS

In experiment 1, three-point bending test suggested that PEMF improved the biomechanical quality of diabetic bone tissues, evidenced by increased maximum load, stiffness, and energy absorption. Microcomputed tomography analysis demonstrated that DM-induced bone architecture deterioration was partially reversed by PEMF, evidenced by increased Tb.N, Tb.Th, BV/TV, and Conn.D and reduced Tb.Sp and SMI. Serum OC analysis indicated that PEMF partially prevented DM-induced decrease in bone formation. In experiment 2, no significant difference in the bone resorption marker TRACP5b was observed. These biochemical findings were further supported by the dynamic bone histomorphometric parameters BFR/BS and Oc.N/BS.

CONCLUSIONS

The results demonstrated that PEMF could partially prevent DM-induced bone strength and architecture deterioration and improve the impaired bone formation. PEMF might become a potential additive method for inhibiting diabetic osteoporosis.

Preservation of islet survival by upregulating α3 integrin signaling: the importance of 3-dimensional islet culture in basement membrane extract

AIM

Islet transplantation is a promising treatment to cure diabetes, but is associated with a high rate of early graft failure. The isolation process leads to the loss of the surrounding extracellular matrix, resulting in eventual islet disintegration and apoptosis. The purpose of this study was to determine the effects on the viability of isolated islets of embedding islets in reconstituted basement membrane extract (BME), which is similar to the normal peri-islet BM composition in vivo.

METHODS

Isolated mouse islets were embedded in BME gel for 24 or 48 hours. Expression of caspase-3, α3, and α5, focal adhesion kinase (FAK), phosphor-FAK, and pancreatic duodenal homeobox factor (PDX)-1 were detected with Western immunoblotting.

RESULTS

Impaired aggregation of single islet cells could only be observed in non-BME medium. Islets embedded in BME gel were partially protected from anoikis showed decreased caspase-3 compared with non-BME islets. We also observed an increase of α3 integrin, FAK protein level, and FAK activity. Furthermore, expression of PDX-1 was preserved at 48 hours, suggesting a positive contribution of BME to β-cell activity.

CONCLUSION

These results indicated that embedding islets in BME can upregulate α3 integrin, which may result in preservation of viability and function of isolated islets.

EGFR, TS, and ERCC1 expression in penile squamous cancer (PSC)

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Background: PSC is an aggressive disease with devastating consequences. While near-universal EGFR overexpression has been documented, little is known about its clinical implications, and the potential role of KRAS mutations has not been described. In other tumor types, ERCC1 and TS expression are associated with response to platinum and 5FU chemotherapy, but have not yet been evaluated in PSC.

Methods: After IRB approval, 28 PSC patients treated at LAC-USC were identified with tumor specimens available. Testing for EGFR, TS, and ERCC1 expression relative to internal standard gene was performed by real-time RT-PCR and correlated with clinical features.

Results: The median age was 45 (30-78). There were 2 Black, 1 Asian, 1 White, and 15 Hispanic men; 9 had unspecified race. T stages included 4 Tis, 6 T1, 17 T2, and 9 T3; 11 men had lymph node (LN) involvement. No KRAS mutations were identified. EGFR had the highest relative expression (median 4.65, range 1.6-44.2), followed by TS (median 1.69, range 0.49-4.69); ERCC1 overexpression was rare (median 0.54, range 0.21-1.29). Higher EGFR expression was significantly associated with poor differentiation (median 12.5 compared to 3.6 for moderate/well differentiated tumors) on continuous (p=0.03 by Mann Whitney) and cut-point analysis using >7 (two- sided p=0.03 by Fisher's exact test) but did not correlate with stage. Stage > T2 showed a trend toward higher risk of LN involvement (p=0.06 by chi square). There was no correlation between differentiation and stage, and no significant correlation for ERCC1 or TS with grade or stage.

Conclusions: EGFR overexpression is common in PSC and correlates with tumor grade but not stage, suggesting it may be important for disease progression. The absence of KRAS mutations may portend responsiveness to EGFR- targeted therapy based on experience in other tumors. Low ERCC1 as an association with platinum response will be explored in an expanded cohort.

No significant financial relationships to disclose.

Microwave Sintering of Zirconia Toughened Mullite (ZTM)

Microwave sintering of zirconia toughened mullite (ZTM) has been performed in a single mode applicator. In comparison with conventional sintering, microwave processing of ZTM leads to a higher density and finer grain size. Microstructure of microwave sintered ZTM was characterized by TEM and HRTEM techniques. The pinning of intergranular ZrO2 dispersoids retarded the grain growth of mullite matrix. The observation of a considerable number of trans-granular microcracks indicates that microcracking toughening is the main toughening mechanism for ZTM.