The number of death due to cancer has been increasing in Korea. Chemotherapy is known to cause side effects because it damages not only cancerous cells but healthy cells. Recently, attention has focused on food-derived chemopreventive and anti-tumor agents or formulations with fewer side effects. Kimchi, most popular and widely consumed in Korea, contains high levels of lactic acid bacteria and has been shown to possess chemopreventive effects. This review focuses on Weissella cibaria and Lactobacillus plantarum, the representatives of kimchi lactic acid bacteria, in terms of their abilities to prevent cancer. Further studies are needed to understand the mechanisms by which lactic acid bacteria in kimchi prevent carcinogenic processes and improve immune functions.

We studied the effects of zinc deficiency on hepatic androgen metabolism and aromatization, androgen and estrogen receptor binding, and circulating levels of reproductive hormones in freely fed, pair-fed and zinc deficient rats. Hepatic conversion of testosterone to dihydrotestosterone was significantly less, but formation of estradiol from testosterone was significantly greater in rats fed the zinc-deficient diet compared with freely fed and pair-fed control rats. There were significantly lower serum concentrations of luteinizing hormone, estradiol and testosterone in rats fed the zinc-deficient diet. No difference in the concentration of serum follicle-stimulating hormone was observed between the zinc-deficient group and either control group. Scatchard analyses of the receptor binding data showed a significantly higher level of estrogen receptor in zinc-deficient rats (36.6 +/- 3.4 fmol/mg protein) than in pair-fed controls (23.3 +/- 2.2 fmol/mg protein) and a significantly lower level of androgen binding sites in rats fed the zinc-deficient diet (6.7 +/- 0.7 fmol/mg protein) than in pair-fed control rats (11.3 +/- 1.2 fmol/mg protein). There were no differences in hepatic androgen and estrogen receptor levels between freely fed and pair-fed controls. These findings indicate that zinc deficiency reduces circulating luteinizing hormone and testosterone concentrations, alters hepatic steroid metabolism, and modifies sex steroid hormone receptor levels, thereby contributing to the pathogenesis of male reproductive dysfunction.

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Lead (Pb) is a toxic heavy metal widely distributed in the environment. Recent studies suggest oxidative stress as one possible mechanism involved in Pb poisoning. The unicellular algae Chlorella vulgaris (CV) contains various bioactive substances with antioxidant for the prevention of oxidative stress by metals. We investigated the protective effects of CV on the oxidative system in five groups of male Sprague-Dawley rats fed American Institute of Nutrition (AIN)-76 diet, plus 2, 5 or 10% CV for 4 weeks. All animals were exposed to 200 mg/l lead acetate by drinking water except for the control (tap water). Body weight gains were significantly reduced in the Pb-exposed group (64%) relative to the control and CV groups. Brain weights were significantly increased in the Pb-exposed group (44%) relative to the others. In the experimental period, food intake, water intake and Pb intake were not different among the groups. The levels of Pb (87%) in brain obtained from the Pb-exposed group were significantly increased compared to the other groups. The levels of oxidative stress parameters in the brain such as superoxide dismutase (36%), glutathione peroxidase (63%), and glutathione reductase (30%) were decreased in the Pb-exposed group relative to the control but markedly increased in the CV groups. The CV also significantly increased glutathione levels by approximately 1.7-fold over the Pb-exposed group, while the malondialdehye concentration significantly decreased by approximately 47-71%. Based on these results, we found alterations in several indicators of oxidative stress of Pb intoxication, suggesting the antioxidant potential of CV. Therefore, CV may have protective effects on brain damage of low-level and short-term Pb exposure in the brains of rats.

These results suggest that ASSE may ameliorate obesity, insulin resistance and oxidative damage in high-fat diet-induced obese mice.

The biochemical mechanisms of Chlorella vulgaris protection against cadmium (Cd)-induced liver toxicity were investigated in male Sprague-Dawley rats (5 weeks of age, weighing 90-110 g). Forty rats were randomly divided into one control and three groups treated with 10 ppm Cd: one Cd without Chlorella (Cd-0C), one Cd with 5% Chlorella (Cd-5C), and one Cd with 10% Chlorella (Cd-10C) groups. The rats had free access to water and diet for 8 weeks. Body weight gain and relative liver weight were significantly lower in the Cd-0C group than in Cd-5C and Cd-10C groups. Rats in the Cd-0C group had significantly higher hepatic concentrations of Cd and metallothioneins (MTs) than in the Cd-5C or Cd-10C group. The hepatic MT I/II mRNA was expressed in all experimental rats. MT II was more expressed in the Cd-5C and Cd-10C groups than in the Cd-0C group. Morphologically, a higher level of congestion and vacuolation was observed in the livers of the Cd-0C group compared to those of the Cd-5C and Cd-10C groups. Therefore, this study suggests that C. vulgaris has a protective effect against Cd-induced liver damage by reducing Cd accumulation and stimulating the expression of MT II in liver. However, the details of the mechanism of C. vulgaris on liver toxicity remains to be clarified by further studies.

This study compared the ability of genistein, a soy isoflavone, with that of 17 beta-estradiol to prevent bone loss in cadmium (Cd)-exposed ovariectomized (OVX) rats during growth. Female Wistar rats (4 weeks old) were either sham-operated (SH; n = 9/group) or OVX and placed on experimental diets (n = 9/group): OVX; OVX rats fed 50 ppm of CdCl(2) (OVX-Cd); OVX fed 50 ppm of CdCl(2) and 10 microg/kg of body weight genistein (OVX-Cd-G); and OVX fed 50 ppm of CdCl(2) and 10 microg/kg of body weight estrogen (OVX-Cd-E). All rats were given free access to AIN-76 modified diet and drinking water, with or without Cd, for 8 weeks. The OVX groups gained more body weight than the SH group. Femoral weight was increased by feeding genistein and estradiol, whereas femoral length among groups was not significantly different. Femoral Cd content was significantly higher in the OVX-Cd group than in the other groups. Both serum osteocalcin and calcium (Ca) concentrations, as well as urinary Ca, were significantly higher in the OVX-Cd group than in the other groups. Urinary excretion of Cd was significantly increased in Cd-OVX-G rats, and fecal Cd excretion was increased by feeding both genistein and estradiol. Femoral histomorpological changes in proliferative cartilage and hypertrophic cells in the OVX-Cd group showed that both cell types were decreased by feeding Cd, and irregular arrangements were observed in proliferative cells. However, both cells types exhibited normal distribution in OVX-Cd-G and OVX-Cd-E groups. These findings suggest that Cd/OVXinduced osteopenia or osteoporosis probably results from an increase in bone turnover. Genistein may be involved in stimulating Cd excretion and inhibiting Ca excretion from bone.

Salmonella contamination in chicken samples can cause major health problems in humans. However, not only the effects of antibiotic treatment during growth but also the impacts of the poultry slaughter line on the prevalence of Salmonellae in final chicken meat sold to consumers are unknown. In this study, we compared the isolation rates and antimicrobial resistance of Salmonellae among antibiotic-free, conventional, conventional Korean native retail chicken meat samples, and clonal divergence of Salmonella isolates by multilocus sequence typing. In addition, the distribution of extended-spectrum β-lactamase (ESBL) genes in ESBL-producing Salmonella isolates was analyzed. A total of 72 retail chicken meat samples (n = 24 antibiotic-free broiler [AFB] chickens, n = 24 conventional broiler [CB] chickens, and n = 24 conventional Korean native [CK] chickens) was collected from local retail markets in Seoul, South Korea. The isolation rates of Salmonellae were 66.6% in AFB chickens, 45.8% in CB chickens, and 25% in CK chickens. By analyzing the minimum inhibitory concentrations of β-lactam antibiotics with the disc-diffusion test, we found that 81.2% of Salmonella isolates from AFB chickens, 63.6% of isolates from CB chickens, and 50% of isolates from CK chickens were ESBL producers; all ESBL-positive isolates had the CTX-M-15 genotype. Interestingly, all ESBL-producing Salmonellae were revealed as ST16 by multilocus sequence typing and had the genetic platform of blaCTX-M gene (IS26-ISEcp1-blaCTX-M-15-IS903), which was first reported in Salmonellae around the world. The Salmonella ST33 strain (S. Hadar) isolated in this study has never been reported in South Korea. In conclusion, our findings showed that antibiotic-free retail chicken meat products were also largely contaminated with ESBL-producing Salmonellae and that their ESBL genes and genetic platforms were the same as those isolated from conventional retail chicken meat products.