Antimicrobial and antitumor activity and diversity of endophytic fungi from traditional Chinese medicinal plant Cephalotaxus hainanensis Li.

Endophytes from Cephalotaxus hainanensis Li, an important source of anti-leukemia drugs, have not been widely explored. In this study, 265 endophytic fungal isolates from C. hainanensis Li were screened for antimicrobial activities against tilapia, banana, rice, and rape and for antitumor activities against human leukemia cell lines (K562, NB4, and HL-60). Diversity was also analyzed. The results showed that 17.7% of the endophytic fungi had antimicrobial activities against at least three different test microbes, and activity against Fusarium oxysporum RKY102 was the highest at 15.8%. Cytotoxicity against at least one tumor cell line tested was observed in 18.5% of the endophytic fungi; with the highest value of 10.6% against K562. The endophytic fungal strains also showed relatively high activities against K562, NB4, and HL-60 while relatively fewer strains were cytotoxic against the human hepatic Hep-G2 and colon LoVo cancer cell lines. Thirty endophytic fungal strains showed both high antimicrobial and antitumor activities. Moreover, the analyses of the diversity of the 30 highly active strains showed they belonged to 20 species from 14 genera, and this is the first report of endophytic fungi Albonectria rigidiuscula, Colletotrichum magnisporum, and Nemania diffusa being isolated from Cephalotaxus plants. These findings suggest that natural antibacterial products for humans and tilapia; antifungal compounds for rice, rape, and banana; and antitumor compounds for leukemia therapy could be isolated from fungal strains derived from C. hainanensis Li.

Effect of hyperphosphatemia on gene expression of the Na-Pi cotransporter in rats.

We investigated the effect of high phosphorus content on the sodium-phosphate cotransporter (NaPi-IIa and NaPi-IIl). Forty-eight Sprague-Dawley rats were divided into 3 groups: high-phosphorus group (HP) with fructose diphosphate sodium injection; self-manufactured low-phosphorus diet group (LP); and normal diet group (NP). At the 1st, 2nd, 4th, and 6th weeks, 4 rats from each group were sacrificed for detecting serum levels of calcium, phosphorus, and intact parathyroid hormone. Semi-quantitative retrovirus-polymerase chain reaction was used to detect the expression of NaPi-IIa and NaPi-III mRNA in kidney. At the 1st, 2nd, 4th, and 6th weeks, serum phosphorus and parathyroid hormone levels in HP group were significantly higher than those in LP and NP groups (P < 0.05). Serum calcium levels in the 3 groups showed no difference (P > 0.05). Comparing the expression of NaPi-IIa mRNA in HP group with LP and NP groups, NaPi-IIa mRNA expression was significantly reduced in HP group (P < 0.05), while NaPi-IIa mRNA expression in LP group began increasing at the 4th week (P < 0.05). At the 1st, 2nd, and 4th weeks, the expression of NaPi-III mRNA in HP, LP, and NP groups showed no clear differences (P > 0.05), while at the 6th week in HP group, NaPi-III mRNA expression was slightly increased compared to in LP and NP groups (P < 0.05). Hyperphosphatemia significantly affected NaPi-IIa and NaPi-III mRNA expression, and a factor promote an increase in intact parathyroid hormone independently of calcium.

Analysis of the association between polymorphisms in the vitamin D receptor (VDR) gene and dental caries in a Chinese population.

Environmental influences on the development and progression of dental caries are well known; however, there is little evidence of a genetic component imparting susceptibility to dental caries. The aim of this study was to investigate the relationship between a single nucleotide polymorphism in the vitamin D receptor TaqI locus and dental caries susceptibility in a Chinese population. This case-control study was conducted with a case group (264 patients with dental caries from northwestern China) and a control group (219 individuals without dental caries or systemic disease from the same area). DNA was extracted from the peripheral venous blood of the study participants; the distribution of TaqI locus genotypes and allele frequencies was determined via polymerase chain reaction-restriction fragment length polymorphism. The data obtained were statistically analyzed using the Hardy-Weinberg equilibrium and Chi-square test. The frequency of the Tt genotype in the case group (14.0%) was significantly higher than that in the control group (4.3%), as determined using the genotype TT as the reference. The risk of dental caries was increased 3.8-fold in individuals with the heterozygous Tt genotype compared to that in the individuals with the TT genotype. The proportion of the 't' allele in the case group (7.0%) and the control group (2.1%) was observed to be significantly different [P = 0.0003; OR = 3.592, confidence interval 95% (1.790-7.208)]. Our results therefore suggested that the allele 't' might be a genetic factor determining dental caries susceptibility in individuals from the northwest of China.

Establishment and characterization of a rat model of hyperphosphatemia.

We established a rat model of hyperphosphatemia and investigated the systemic effects of high phosphorus (P). Sprague Dawley rats were randomly divided into high (HP), low (LP), and normal (NP) P groups (N = 12 each), which received injections of fructose diphosphate sodium, or were fed self-manufactured low phosphorus or normal diets, respectively. In each group, 4 rats were sacrificed at the first, third, and sixth week to detect the serum (Scr) and urinary creatinine and P, and calcium (Ca) levels. The HP group's serum P and intact parathyroid hormone (iPTH) were significantly higher than those in the other groups at the first, third, and sixth weeks, (P < 0.05); the LP group's serum P was lower than the NP group's at the third week (P < 0.05), while at the sixth week, the serum P and iPTH were lower (P < 0.05). No significant differences were detected for blood Ca+ (P > 0.05). The HP group's Scr increased (P < 0.01), whereas the fractional excretion decreased (P < 0.05) significantly. Thighbone and lumbar spine bone densities differed significantly between groups in the third week (P < 0.05); LP group densities were lower than NP group measures (P < 0.05). Crystallized stones were not observed microscopically following hematoxylin and eosin staining of the kidney. We successfully established a hyperphosphatemia rat model, and high blood P was found to significantly influence renal function and bone density. These results might provide a foundation to study the effects of hyperphosphatemia in rats.

Genetic polymorphisms in the carbonic anhydrase VI gene and dental caries susceptibility.

We investigated the role of 7 single nucleotide polymorphisms in the carbonic anhydrase (CA) VI gene (rs2274328, rs17032907, rs11576766, rs2274333, rs10864376, rs3765964, and rs6680186) and the possible association between these polymorphisms and dental caries susceptibility in a Northwestern Chinese population. We collected samples from 164 high caries experience and 191 very low caries experience and conducted a case-control study according to the number of decayed, missing, and filled teeth index and genotyped the 7 polymorphisms using a 384-well plate format with the Sequenom MassARRAY platform. Individuals carrying the rs17032907 TT genotype were more likely to have an increased risk of dental caries compared with carriers of the C/C genotype in the co-dominant model, with an odds ratio (95% confidence interval) of 2.144 (1.096-4.195). We also found that the haplotype (ACA) (rs2274328, rs17032907 and rs11576766) was associated with a low number of decayed, missing, and filled teeth index with an odds ratio (95% confidence interval) of 0.635 (0.440-0.918). However, we found no association between dental caries susceptibility and the rs2274328, rs11576766, rs2274333, rs10864376, rs3765964, and rs6680186 polymorphisms and other haplotypes. The rs17032907 genetic variant and the haplotype (ACA) of CA VI may be associated with dental caries susceptibility.