Computation of multiweight

In learning machines the key problem is to determine weight vectors satisfying linear inequalities. In two-category classification only one weight is needed, but in multicategory classification the weight vectors which have to be found are as many as the number of pattern classes. The letter shows that, for linear machines, it is necessary to find only one weight vector, which the authors call the multiweight, by applying the steepest descent method in a learning algorithm.     

Assessment of phenolic content and free radical-scavenging capacity of some Thai indigenous plants

Ethanolic extracts from various parts of 26 Thai indigenous plants were examined for phenolic constituents and free radical scavenging capacity, to determine their potential as a source of natural antioxidants. Total phenolic content and total flavonoid content were evaluated according to the Folin-Ciocalteu procedure, and a colorimetric method, respectively. The results showed that total phenolic compounds and flavonoid content were higher in seed extracts of berries used in wine production, while the levels in extracts obtained from herbs and vegetables were lower. Chewing plants which have an astringent taste gave a significantly higher total phenolic content and flavonoid content. Antiradical activity determined from 1/EC₅₀ by the DPPH radical-scavenging method was highest in wine production seeds and chewing plants. The correlation coefficient from regression analysis showed a positive relationship between total phenolic and total flavonoid content (r = 0.9). The results suggest that ethanolic extracts of some Thai indigenous plants exhibit a potential for use as natural antioxidants.     

Molecular mechanism underlying anti-apoptotic and anti-inflammatory effects of Mamao (Antidesma thwaitesianum Müll. Arg.) polyphenolics in human breast epithelial cells

There has been increasing interest in finding natural antioxidants to prevent free radical damage and retard the progress of chronic inflammatory diseases. Our previous data demonstrated the strong antioxidant properties of polyphenolics in Mamao seed (MS) and Mamao marc (MM) extracts. In this study we further investigated the effect of MS and MM polyphenolics on hydrogen peroxide (H₂O₂)-induced apoptosis and tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation, using human breast epithelial (MCF10A) cells. MS and MM extracts conferred dose-dependent protection against H₂O₂-induced apoptosis by inhibiting PARP/caspase-3 cleavage, inducing anti-apoptotic Bcl-2 expression, and down-regulating pro-apoptotic Bax. Moreover, MS and MM polyphenolics inhibited TPA-induced COX-2 and NF-κB activation by blocking the degradation of cytoplasmic IκBα, as well as subsequent nuclear translocation of p65 and attenuation of the activation of ERK, but not JNK and p38. These data establish the molecular mechanism for the anti-apoptotic and anti-inflammatory effects of MS and MM polyphenolics.     

In-house direct cELISA for determining aflatoxin B1 in Thai corn and peanuts.

To overcome the problem of aflatoxins (AF) in Thai foods, a sensitive in-house direct cELISA using monoclonal antibody (mAb) was established and compared with a commercial ELISA kit and thin-layer chromatography for the determination of AFB(1) levels in corn and peanuts. Among eight in-house mAbs (AF1-8), AF5 was used in the direct cELISA owing to its excellent specificity and sensitivity with the detection limit of 4 microg kg(-1). The recovery of AFB(1) spiked at 5, 10, 20, 40 and 80 microg kg(-1) ranged from 88.1 to 99.5%. Correlation coefficients of the ELISA with the commercial ELISA kit and thin-layer chromatography were 0.912 and 0.802 for corn, and 0.941 and 0.832 for peanuts, respectively (p<0.05). The cost per sample was estimated to be about 16 times lower than the commercial ELISA kit. Subsequently, the in-house direct cELISA was successfully applied to screen the contamination of AFB(1) in Thai corn and peanuts. Mean levels of AFB(1) (per cent positive) were 73 microg kg(-1) (85.7%) in corn and 102 microg kg(-1) (67.9%) in peanuts, for which 46.4% of both foods were above the Thailand regulation limit (20 microg kg(-1)).     

Antioxidant Activities of Polyphenolic Compounds Isolated from Antidesma thwaitesianum Müll. Arg. Seeds and Marcs

ABSTRACT: Antidesma thwaitesianum Müll. Arg. or mao is widely used as commercial products of juice and wine in Thailand. As a result, waste products from the mao plant, such as mao seeds (MS) and mao marcs (MM), are plentiful. We aimed to purify and analyze polyphenolic content in both MS and MM and to investigate the radical scavenging activities of these polyphenolics against 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) and 2,2′‐Azinobis (3‐ethylbenzothiazoline 6‐sulphonate) (ABTS) radicals and thiobarbituric acid reactive products (TBARP). The results showed MS and MM to be an abundant source of polyphenols (97.32 to 130 mg gallic acid equivalents [GAE]/g) and proanthocyanidins. The radical scavenging activities of MS/MM against DPPH and ABTS radicals (IC₅₀ of 0.85 to 1.21 μg/mL) were significantly higher (P < 0.05) than that of standard trolox (IC₅₀ of 5.05 μg/mL). Activity of MS/MM extracts were 3.74 and 3.80 μg/mL trolox eq/g f.w. for the DPPH and ABTS assays, respectively. The oxidation of erythrocyte membranes using 2‐thiobarbituric acid demonstrated that the protective effect of MS/MM on lipid peroxidation is as strong as grape seed proanthocyanidin extract. These findings suggest that polyphenolic compounds and proanthocyanidins isolated from these mao extracts had much higher antioxidant activities than those of standard trolox and exhibited similar antioxidant potential to grape seed proanthocyanidin extract. These findings may also increase value of mao waste products and allow development of commercial health products.     

Developmental toxicity of steviol, a metabolite of stevioside, in the hamster

Family history of hypertension (positive and negative) and gender groups were compared on cardiovascular responses at rest, during stressors and during recovery. Two tasks were employed, mental arithmetic and an anger recall interview. Both levels and reactivity measures of blood pressure, heart rate, cardiac output and total peripheral resistance were included. In addition, participants filled out several questionnaires measuring state feelings during the task and recovery periods, trait anger/hostility and emotions. Both men and women with a positive family history of hypertension exhibited higher tonic levels of blood pressure and heart rate at rest, recovery and during both tasks. They also exhibited greater heart rate reactivity during the mental arithmetic task and greater blood pressure reactivity to both tasks when post-math recovery, but not initial rest, was used as a covariate. Positive family history individuals reported less trust and gregariousness, more depression and aggression, less awareness of somatic responses to the tasks and less effort to relax during the post-task rest periods. Finally, significant correlations were found between low anger expression how anger experience and high anger control and task SBP levels in positive family history individuals.     

Host-Assisted Delivery of a Model Drug to Genomic DNA: Key Information from Ultrafast Spectroscopy and in silico Study

Drug delivery to a target without adverse effects is one of the major criteria for clinical use. Herein, we have made an attempt to explore the delivery efficacy of SDS surfactant in a monomer and micellar stage during the delivery of the model drug, Toluidine Blue (TB) from the micellar cavity to DNA. Molecular recognition of pre-micellar SDS encapsulated TB with DNA occurs at a rate constant of k₁ ∼652 s⁻¹. However, no significant release of encapsulated TB at micellar concentration was observed within the experimental time frame. This originated from the higher binding affinity of TB towards the nano-cavity of SDS at micellar concentration which does not allow the delivery of TB from the nano-cavity of SDS micelles to DNA. Thus, molecular recognition controls the extent of DNA recognition by TB which in turn modulates the rate of delivery of TB from SDS in a concentration-dependent manner.