Fragment-similarity-based QSAR (FS-QSAR) algorithm for ligand biological activity predictions

Quantitative structure-activity relationship (QSAR) studies are useful computational tools often used in drug discovery research and in many scientific disciplines. In this study, a robust fragment-similarity-based QSAR (FS-QSAR) algorithm was developed to correlate structures with biological activities by integrating fragment-based drug design concept and a multiple linear regression method. Similarity between any pair of training and testing fragments was determined by calculating the difference of lowest or highest eigenvalues of the chemistry space BCUT matrices of corresponding fragments. In addition to the BCUT-similarity function, molecular fingerprint Tanimoto coefficient (Tc) similarity function was also used as an alternative for comparison. For validation studies, the FS-QSAR algorithm was applied to several case studies, including a dataset of COX2 inhibitors and a dataset of cannabinoid CB2 triaryl bis-sulfone antagonist analogues, to build predictive models achieving average coefficient of determination (r(2)) of 0.62 and 0.68, respectively. The developed FS-QSAR method is proved to give more accurate predictions than the traditional and one-nearest-neighbour QSAR methods and can be a useful tool in the fragment-based drug discovery for ligand activity prediction.

Experience with adrenal schwannoma in a Chinese population of six patients

OBJECTIVES

Benign adrenal schwannoma is an extremely uncommon cause of incidentaloma. This article describes our experience with the diagnosis and treatment of adrenal schwannoma in a Chinese population of 6 patients. To our knowledge, this is the largest series of this uncommon adrenal tumor treated in a single center.

METHODS

From May 1999 to May 2009, 6 patients with incidentally discovered adrenal schwannoma were operated on at a tertiary referral hospital in Eastern China. Clinical details, radiographic features, laboratory examinations, pathological findings, and follow-up data of these patients were analyzed.

RESULTS

Of the 6 patients, 4 were females (F) and 2 were males (M), with a mean age of 40.5 yr (range: 30-47, M:F=2:1). The 6 patients were managed with open unilateral adrenalectomy; 5 patients had schwannomas on the left side, and 1 on right side. Abnormal urine catecholamine was detected in 1 patient. The mean pathological size of these tumors was 4.3 ± 1.1 cm. The diagnosis of schwannoma was based on classic histological findings, and supported by immunohistochemistry of S-100, vimentin, and ABC positivity. In the follow- up of 47.5 ± 32.3 months, no recurrence and metastasis were observed.

CONCLUSIONS

Although there may be some clues for radiological diagnosis of adrenal schwannoma, preoperative misdiagnosis is not infrequent. Those tumors may occasionally have endocrine function. Histological examination is the key of diagnosis, and surgical resection is the treatment of choice once malignancy cannot be excluded by preoperative analyses.

Isolation and characterization of 21 novel polymorphic microsatellite loci in the Chinese soft-shelled turtle Pelodiscus sinensis

Twenty-one novel polymorphic microsatellite loci were isolated from the Chinese soft-shelled turtle, Pelodiscus sinensis (Trionychidae). This is a commonly consumed Asian species, especially in China, where it is reared in large numbers on farms. We screened 34 unrelated individuals from Wuhu of Anhui province in China and detected high levels of polymorphism for all 21 loci, with the number of alleles/locus ranging from 5 to 23 (mean 15.67). The expected and observed heterozygosities ranged from 0.421 to 0.946 and from 0.324 to 0.941, respectively. Hence, these microsatellites could facilitate studies on genetic diversity and population structure and marker-assisted breeding of this vulnerable species.

Differential expression of serine-threonine kinase receptor-associated protein in patients with systemic lupus erythematosus

The serine-threonine kinase receptor-associated protein (STRAP), a 39 kDa protein localized predominantly in cytoplasm, is an important inhibitor of transforming growth factor beta (TGF-ß) signaling and a regulator of cell proliferation. To investigate the application of STRAP as a novel biomarker in evaluating the pathological condition of systemic lupus erythematosus (SLE), and to determine the possible involvement of STRAP in SLE pathogenesis, the expression levels of STRAP in peripheral blood mononuclear cells (PBMC) of SLE patients were analyzed. PBMC were collected from six patients with active SLE, six with stable SLE and six healthy controls; after protein extraction and concentration determination, the samples were labeled with reagents for isobaric tagging for relative and absolute protein quantification (iTRAQ) and detected by tandem mass spectrometry. The initial proteomic analysis identified and quantified hundreds of proteins. Of these, STRAP was found to decrease more than three-fold in active SLE patients compared with healthy controls (the relative ratio was 0.291). The under-expression of STRAP in active SLE was further verified by western blot in larger independent sample sets. Clinical data analyses revealed that the levels of STRAP in SLE inversely correlated to the SLE disease activity index (SLEDAI) (r = -0.607, p < 0.05). These results indicate that the under-expression of STRAP may be a negative factor in the pathogenic process of SLE; as a result, this may also be of clinical significance as a potential condition-specific indicator of active SLE.