Improvement of carcinogenicity prediction performances based on sensitivity analysis in variable selection of SVM models

A new sensitivity analysis (SA) method for variable selection in support vector machine (SVM) was proposed to improve the performance level of the QSAR model to predict carcinogenicity based on the correlation coefficient (CC) method used in our preceding study. The performances of both methods were also compared with that of the F-score (FS) method proposed by Chang and Lin. The 911 non-congeneric chemicals were classified into 20 mutually overlapping groups according to contained substructures, and a specific SVM model created on chemicals belonging to each group was optimized by searching the best set of SVM parameters while successively omitting descriptors of lower absolute values of sensitivity, CC or FS until the maximum predictive performance was obtained. The SA method improves the overall accuracy from 80% of CC and FS to 84%, which is considerably higher than those of existing models for predicting the carcinogenicity of non-congeneric chemicals. It selects the optimum sets of effective descriptors fewer than the CC and FS methods, and is not time-consuming and can be applied to a large set of initial descriptors. It is concluded that SA is superior as a variable selection method in SVM models.

Feasibility of 2nd generation STS retinal prosthesis in dogs

We developed a 2(nd) generation suprachoroidal transretinal stimulation (STS) system with a 49 channel electrode array and implanted in 2 dogs. One month after surgery, all electrodes were functioning and the ocular fundus was normal in both dogs. The results indicate the 2(nd) generation STS retinal prosthesis is feasible and can be considered for clinical use.

Histone deacetylase inhibitors suppress mechanical stress-induced expression of RUNX-2 and ADAMTS-5 through the inhibition of the MAPK signaling pathway in cultured human chondrocytes

OBJECTIVE

To investigate the inhibitory effects and the regulatory mechanisms of histone deacetylase (HDAC) inhibitors on mechanical stress-induced gene expression of runt-related transcription factor (RUNX)-2 and adisintegrin and metalloproteinase with thrombospondin motif (ADAMTS)-5 in human chondrocytes.

METHODS

Human chondrocytes were seeded in stretch chambers at a concentration of 5 × 10(4)cells/chamber. Cells were pre-incubated with or without HDAC inhibitors (MS-275 or trichostatin A; TSA) for 12h, followed by uniaxial cyclic tensile strain (CTS) (0.5Hz, 10% elongation), which was applied for 30 min using the ST-140-10 system (STREX, Osaka, Japan). Total RNA was extracted and the expression of RUNX-2, ADAMTS-5, matrix metalloproteinase (MMP)-3, and MMP-13 at the mRNA and protein levels were examined by real-time polymerase chain reaction (PCR) and immunocytochemistry, respectively. The activation of diverse mitogen-activated protein kinase (MAPK) pathways with or without HDAC inhibitors during CTS was examined by western blotting.

RESULTS

HDAC inhibitors (TSA: 10 nM, MS-275: 100 nM) suppressed CTS-induced expression of RUNX-2, ADAMTS-5, and MMP-3 at both the mRNA and protein levels within 1h. CTS-induced activation of p38 MAPK (p38), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) MAPKs was downregulated by both HDAC inhibitors.

CONCLUSION

The CTS-induced expression of RUNX-2 and ADAMTS-5 was suppressed by HDAC inhibitors via the inhibition of the MAPK pathway activation in human chondrocytes. The results of the current study suggested a novel therapeutic role for HDAC inhibitors against degenerative joint disease such as osteoarthritis.

Akt phosphorylation in human chondrocytes is regulated by p53R2 in response to mechanical stress

OBJECTIVE

The p53 tumor-suppressor protein p53R2 is activated in response to various stressors that act on cell signaling. When DNA is damaged, phosphorylation of p53 at its Ser 15 residue induces p53R2 production. The role of p53R2 in chondrocytes remains poorly understood. In this study, we evaluated in chondrocytes, p53R2 expression and its regulation in response to mechanical stress. Furthermore, we investigated the function of p53R2 in relation to mechanotransduction.

METHODS

Osteoarthritis (OA) cartilage obtained from total knee replacements and normal cartilage obtained from femoral neck fractures was used to measure p53R2 expression by using immunohistochemistry, western blotting, and real-time polymerase chain reaction (PCR). The OA chondrocytes were subjected to a high magnitude of cyclical tensile strain by using an FX-2000 Flexercell system. Next, sulfated glycosaminoglycan (sGAG) production was quantified in these cells. Protein expression of p53R2, and phosphorylation of Akt, p38MAPK, ERK1/2, and JNK was also detected using western blotting. Moreover, Akt phosphorylation was detected after transfecting the cells with p53R2-specific small interfering RNA (siRNA).

RESULTS

Expression of p53R2 was significantly increased in OA chondrocytes and in chondrocytes after applying 5% tensile strain to the cells. However, Akt phosphorylation was down-regulated in OA chondrocytes after the strain, and was up-regulated after transfection of p53R2. sGAG protein as well as collagen type II and aggrecan mRNA was increased following transfection of p53R2-specific siRNA after 5% tensile strain.

CONCLUSIONS

p53R2 could regulate matrix synthesis via Akt phosphorylation during chondrocyte mechanotransduction. Down-regulation of p53R2 may be a new therapeutic approach in OA therapy.

Salvage lymphadenectomy for cervical lymph node recurrence after esophagectomy for squamous cell carcinoma of the thoracic esophagus

Prognosis of patients with recurrent esophageal cancer is usually unsatisfactory. We have successfully treated five patients with cervical node recurrence after esophagectomy with multimodal treatment including salvage lymphadenectomy. In order to clarify the efficacy of salvage surgery for cervical node recurrence, we have reviewed the clinical course and prognosis of these patients. From August 2004 to December 2007, 30 patients with 33 recurrent sites were treated in the Department of Surgery, Iizuka Hospital. Among these patients, there were five patients with recurrence limited within the cervical nodes. Salvage cervical lymphadenectomy was performed for all five patients. Curative resection was achieved in four patients and reduction surgery followed by planned chemoradiotherapy was performed in another patient. All stations including the suspicious node were dissected and a partial sternotomy was added for one patient whose recurrent tumor was located in the right recurrent nerve node. There was no mortality and one minor complication (subcutaneous hemorrhage) was observed. Median duration of hospital stay was 7 days. Adjuvant chemotherapy was performed for all patients. Median follow-up period was 54 months and all patients are alive without relapse of the disease. Salvage cervical lymphadenectomy is a safe and effective treatment for patients with cervical node recurrence after esophagectomy.

Is patella eversion during total knee arthroplasty crucial for gap adjustment and soft-tissue balancing?

INTRODUCTION

Assessment of soft-tissue balance by the gap technique in Total Knee Arthroplasty (TKA) impacts femoral component rotation positioning. Proper femoral component rotation is a critical factor in TKA, both for adequate patellar tracking and in achieving a symmetrical flexion gap. Soft tissue balance assessment and gap measurements are performed at 90° flexion and with the patella everted in conventional TKA; during MIS-TKA, this step is performed with the patella in situ. We therefore investigated intraoperative joint gap parameters at 90° flexion with and without patellar eversion during conventional TKA, so as to better understand the influence of this intraoperative patellar position factor on final ligament balance.

HYPOTHESIS

Conducting TKA without patellar eversion increases both gap size and gap inclination.

PATIENTS AND METHODS

Twenty-four osteoarthritic knees were included in the study. Joint gap size and inclination were measured intraoperatively on a knee in 90° flexion, with and without patellar eversion.

RESULTS

The joint gap with patella in situ (17.0±3.4 mm) was significantly greater than with patellar eversion (15.4±3.0 mm), as was gap inclination at 90° flexion with the patella in situ (4.9±3.1°) compared to with patellar eversion (4.0±2.9°).

DISCUSSION

The flexion gap inclination obtained without patellar eversion was steeper than with patellar eversion. This induced more externally rotated femoral positioning in absence of patellar eversion. These results ought to be taken into account by surgeons considering switching from conventional to MIS-TKA.

A Novel Prodrug of Salicylic Acid, Salicylic Acid-glycylglycine Conjugate, Utilizing the Hydrolysis in Rabbit Intestinal Microorganisms

The hydrolysis of salicylic acid-glycylglycine conjugate (salicyl-glycylglycine) following oral, intravenous, intracaecal and rectal administration (434, 72, 36 and 36 μmol kg−1, respectively: equivalent to salicylic acid) was examined in rabbits to develop a novel prodrug of salicylic acid. Salicylic acid was detected in the blood 2 h after oral administration of salicyl-glycylglycine and it reached a maximum level (55·6 μg mL−1) at 15 h, whereas a small amount of salicyl-glycylglycine was found in the blood. In contrast, unchanged salicyl-glycylglycine was found mainly in the blood following its intravenous administration, suggesting the involvement of presystemic deconjugation in the hydrolysis of salicyl-glycylglycine. Immediate and very extensive salicyclic acid formation in the caecum was observed following intracaecal administration of salicyl-glycylglycine, suggesting that the intestinal microorganisms were responsible for the biotransformation of this compound. In-vitro incubation of salicyl-glycylglycine with caecal content showed that salicyl-glycylglycine was hydrolysed efficiently in the caecum. Consequently, the blood concentration of salicylic acid was prolonged extensively following rectal administration of salicylglycylglycine, indicating the usefulness of salicyl-glycylglycine as a prodrug of salicylic acid.

Development of a Prodrug of Salicylic Acid, Salicylic Acid-l-alanine Conjugate, Utilizing Hydrolysis by Rabbit Intestinal Microorganisms

The hydrolysis of salicylic acid-l-alanine conjugate (salicyl-l-alanine) following oral, intravenous, intracaecal and rectal administration (60, 10, 5 and 5 mg kg−1, respectively: salicylic acid equivalent) was examined in rabbits. Salicylic acid was detected in the blood 2 h after oral administration of salicyl-l-alanine and reached a maximum concentration at 10 h, whereas salicyl-l-alanine was rapidly eliminated. In contrast, unchanged salicyl-l-alanine only was found following intravenous administration of salicyl-l-alanine, suggesting that presystemic de-conjugation of salicyl-l-alanine was involved. The intestinal mucosal de-conjugation of salicyl-l-alanine was not recognized in the in-situ intestinal sac preparation with complete mesenteric venous blood collection. Immediate and very extensive salicylic acid formation in the caecum was found following intracaecal administration of salicyl-l-alanine. After oral pretreatment of rabbits with kanamycin sulphate, a significant inhibition of salicylic acid formation following intracaecal administration of salicyl-l-alanine was observed, indicating that the intestinal microorganisms were responsible for the biotransformation of salicyl-l-alanine. In-vitro incubation of salicyl-l-alanine with gut contents showed that the major source of its hydrolysis was the hind gut. Consequently, the blood concentration of salicylic acid was prolonged extensively following rectal administration of salicyl-l-alanine, suggesting the usefulness of salicyl-l-alanine as a prodrug of salicylic acid.

Anterior transposition of the ulnar nerve with endoscopic assistance

We treated 20 patients with cubital tunnel syndrome by anterior transposition of the ulnar nerve with endoscopic assistance. Five elbows were classified preoperatively as McGowan's stage 1, 11 as stage 2 and four as stage 3. Excellent outcomes were obtained in nine and good in eight patients. Three patients had fair results. Improvement of symptoms occurred in all patients. There were no serious complications. All ulnar nerves remained anteriorly transposed.

Development and in vivo Demonstration of CMOS-Based Multichip Retinal Stimulator With Simultaneous Multisite Stimulation Capability

A complementary metal-oxide semiconductor (CMOS)-based multichip flexible neural stimulator for retinal prostheses was developed. The multichip retinal stimulator is capable of simultaneous multisite stimulation. An on-chip stimulation generator was implemented on the "unit chip," which is the core device of the multichip retinal stimulator. The performance of the CMOS circuitry was characterized. A new device structure and packaging process was developed. The in vivo retinal stimulation on a rabbit's retina was successfully performed and the multisite stimulation functionality was confirmed.