Thai generic-brand dry canine foods: mutagenicity and the effects of feeding in vivo and in vitro.

BACKGROUND: The commercial pet-food industry and the market value of the pet industry have increased. Most owners are concerned about their pets' health, and prefer commercial pet foods as their regular diet. This study thus aimed to determine whether a selection of local generic-brand dry canine foods had any potential to promote chronic disease. METHODS: Five local, generic-brand, dry canine foods were studied for potential mutagenicity; the effects of long-term consumption were also observed in rats. All canine foods were extracted with distilled water and absolute ethanol. The Ames test was used to detect short-term genetic damage, using Salmonella typhimurium tester strains TA98 and TA100. Simultaneously, the long-term effects were studied in an animal model by observing rats fed with these canine foods, compared with normal rat food, for a period of 15 weeks. RESULTS: Using the water extracts, all dry canine foods studied showed considerable mutagenic effects on the tester strains. One brand affected both tester strains, whereas 3 showed positive to TA98, and one to TA100. With the absolute ethanol extract, three of the five brands had a considerable mutagenic effect on TA98, and another affected TA100. In the long-term test, all rats remained alive until the end of the experiment, exhibited no apparent signs of toxicity or serious illness, and maintained normal bodyweight and weight gain. Serum blood biochemistry and hematological parameters in canine food-fed rats showed some negative effects. Correspondingly, histopathological investigation of their liver and kidneys showed deterioration. CONCLUSIONS: Mutagenic potential and the negative potential health impacts were observed in all local-brand dry canine foods tested.

Functional expression and molecular characterization of Culex quinquefasciatus salivary α-glucosidase (MalI).

Salivary α-glucosidases (MalI) have been much less characterized when compared with midgut α-glucosidases, which have been studied in depth. Few studies have been reported on the partial characterization of MalI, but no clear function has been ascribed. The aim of this study is to purify and characterize the recombinant Culex quinquefasciatus (CQ) α-glucosidase expressed in Pichia pastoris. The cDNA encoding mature Cx. quinquefasciatus α-glucosidase gene with polyhistidine tag (rCQMalIHis) was successfully cloned into the expression vector, pPICZαB, designated as pPICZαB/CQMalIHis. The activity of recombinant rCQMalIHis expressed in P. pastoris could be detected at 3.75U/ml, under optimal culture conditions. The purified rCQMalIHis showed a single band of molecular weight of approximately 92kDa on SDS-PAGE. After Endoglycosidase H digestion, a single band at 69kDa was found on SDS-PAGE analysis, suggesting that rCQMalIHis is a glycoprotein. Additionally, tryptic digestion and LC-MALDI MS/MS analysis suggested that the 69kDa band corresponds to the Cx. quinquefasciatus α-glucosidase. Thus, rCQMalIHis is a glycoprotein. The rCQMalIHis exhibited optimum pH and temperature at 5.5 and 35°C, respectively. The catalytic efficiency (kcat/Km) of the purified rCQMalIHis for maltotriose is higher than those for sucrose, maltotetraose, maltose and p-nitrophenyl-α-glucoside, indicating that the enzyme prefers maltotriose. Additionally, the rCQMalIHis is significantly inhibited by d-gluconic acid δ-lactone, but not by Mg(2+), Ca(2+) and EDTA. The rCQMalIHis is strongly inhibited by acarbose with IC50 67.8±5.6nM, but weakly inhibited by glucose with IC50 115.9±7.3mM.

Purification and characterization of anti-HIV-1 protein from Canna indica L. leaves.

A novel 10 kDa protein with anti-HIV-1 reverse transcriptase (RT) inhibitory activity was isolated from leaves of Canna indica L. using a combination of native-PAGE and ammonium sulfate precipitation. HIV-1 and RT inhibitory activity was measured using a syncytium forming (deltaTat/Rev) MC99 virus in Tat/Rev transfected 1A2 cell line and ELISA technique, respectively. Edman N-terminal and internal amino acid sequence (using LC-MS-MS) determination revealed the 10 kDa Canna indica L. leaf protein as a putative plastocyanin. This is the first report of a plant plastocyanin with HIV-1 RT inhibitory property.

Food behavior and folate status of hill-tribe schoolchildren and women of childbearing age on the northern border of Thailand.

An insight into the folate nutritional status of the population is important from a public health perspective. The protective effect of folate against neural tube defects (NTDs) is widely recognized. To assess the health and nutritional status, especially folate status, of vulnerable hill-tribe groups, a cross-sectional study was conducted on 197 schoolchildren and 136 women of childbearing age in Chaloem Phra Kiat District, Nan Province, Thailand. The nutritional status of the study group was investigated by dietary survey, and blood samples were taken to determine hematocrit, protein, and serum and red blood cell folate. Anthropometric measurements were taken to assess body size, composition and nutritional indexes. The health and nutritional status of the hill-tribe schoolchildren and women of childbearing age were found to be unacceptable, particularly inregard to folate status, which was indicated by low folate levels found in the blood samples, and in the intake of this micronutrient.

Serum leptin concentrations in chronic hepatitis.

The objectives of this research were to investigate the leptin levels among Chronic Hepatitis B Virus (HBV), Chronic Hepatitis C Virus (HCV) and non-alcoholic steatosis hepatitis (NASH) diseases of Thai patients compared with controls. Twenty of each HBV, HCV and NASH patients compared with sixty people as the control group from the Outpatient Department at the Hospital for Tropical Diseases, Bangkok, Thailand were investigated. Fasting blood samples were collected for investigation of leptin concentration, liver enzyme function tests and hematological variables. The serum leptin concentration of liver patients was significantly higher than that of control subjects. It might be due to the accumulations of fat cells in liver disease patients. However, there is no relationship between leptin level and other parameters such as BMI, ALT, AST, ALP and hematological variables. Liver enzyme functions levels are much higher in patients groups. White blood cells counts, platelets and hematocrit values are slightly lower in liver disease patients. Therefore, it is concluded that physiological regulation of leptin maintains in relation to body fat, even in chronic viral liver diseases. This finding and the apparent stage suggest the possibility that in the course of chronic viral diseases, serum leptin levels may reflect the extent of liver dysfunction.

Mutagenicity study of weeds and common plants used in traditional medicine and for animal feed.

Mutagenicity and antimutagenicity potentials were tested using Ames' test in crude distilled water and absolute ethanol extracts from the stems and leaves of Peperomia pellucida (Linn.) Kunth, Eichhornia crassipes Solms, Colocasia esculenta Schott and Brachiaria mutica (Forssk.) Stapf, and the stems of Musa sapientum Linn. No mutagenic effect was found in any of the 10 mg/plate crude extracts of these plants for either TA98 or TA100 of Salmonella typhimurium, in a direct test and a mutagenic induced test by S-9 mix. Both distilled water and absolute ethanol extract of 0.5-10 mg/plate B. mutica showed strong antimutagenicity to AFB1, B(a)P and 4NQO in two tester strains. Ethanol extract of 0.1-0.5 mg/plate C. esculenta also showed antimutagenicity to AFB1, B(a)P and 4NQO in two tester strains, but the 0.5-10 mg/plate water extract had an antimutagenic effect only for B(a)P in TA98. The ethanol extracts of 5 mg/plate B. mutica and 0.5 mg/plate C. esculenta are cytotoxic, as indicated by their partial killing effect.

Cloning, sequencing, and expression of a chitinase-encoding gene from Bacillus circulans No. 4.1.

A chitinase encoding gene from Bacillus circulans No. 4.1 was cloned in Escherichia coli by using pBluescript II SK. The recombinant plasmid containing the 2.6-kb chitinase gene was designated as pCHIB43. The nucleotide sequence revealed a single open reading frame containing 1794 bp and encoding 598 amino acids with a molecular mass of 65.78 kDa. The gene was sequentially deleted; the deletion clones were designated as pC66, pC6S, pSS6, and pEVS. The clones pC6S, pSS6, and pEVS hydrolyzed soluble chitin, but the ability to hydrolyze colloidal chitin was lost. The deduced amino acid sequence was investigated and found to be a chitin-binding domain and a catalytic domain containing 40 and 57 amino acid residues, respectively. A HindIII-SacI fragment of pSS6 was subcloned into pBluescript SK to reverse the orientation of the gene, and the resulting plasmid pSK43 did produce chitinase. Thus, the cloned gene was expressed under the control of a self-promoter.