Spectral radius and k-factor-critical graphs

For a nonnegative integer $k$, a graph $G$ is said to be $k$-factor-critical if $G-Q$ admits a perfect matching for any $Q\subseteq V(G)$ with $|Q|=k$. In this article, we prove spectral radius conditions for the existence of $k$-factor-critical graphs. Our result generalises one previous result on perfect matchings of graphs. Furthermore, we claim that the bounds on spectral radius in Theorem 3.1 are sharp.Comment: 12 page

Effects of Flos carthami on CYP2D6 and on the Pharmacokinetics of Metoprolol in Rats

Flos carthami is a traditional Chinese herbal medicine. Clinically, the Flos carthami Injection has been used concomitantly with other Western drugs and may be used concomitantly with β-blockers, such as metoprolol, to treat cerebrovascular and coronary heart diseases, in China. Metoprolol is a CYP2D6 substrate and is predominantly metabolized by this isozyme. However, we do not know whether there is an effect of Flos carthami on CYP2D6 and the consequences of such an effect. Concern is raised regarding the possible herb-drug interaction. In this report, the effects of Flos carthami on the activity of CYP2D6 in vivo and in vitro and on the pharmacokinetics of metoprolol, in rats, are investigated. To assess the inhibitory potency of Flos carthami, the concentration associated with 50% inhibition (IC50) of dextromethorphan metabolism was determined based on the concentration-inhibition curves. The inhibitory effect of Flos carthami on CYP2D6 was also compared with cimetidine in vitro. Flos carthami could significantly inhibit CYP2D6 in rats both in vitro and in vivo (P < .05) and could slow down the metabolic rate of metoprolol as suggested by prolonged t1/2 (67.45%), by increased Cmax (74.51%) and AUC0−∞ (76.89%). These results suggest that CYP2D6 is a risk factor when Flos carthami is administered concomitantly with metoprolol or other CYP2D6 substrates

Early-Life Intervention Using Exogenous Fecal Microbiota Alleviates Gut Injury and Reduce Inflammation Caused by Weaning Stress in Piglets

Fecal microbiota transplantation (FMT) could shape the structure of intestinal microbiota in animals. This study was conducted to explore the changes that happen in the structure and function of microbiota caused by weaning stress, and whether early-life FMT could alleviate weaning stress through modifying intestinal microbiota in weaned piglets. Diarrheal (D) and healthy (H) weaned piglets were observed, and in the same farm, a total of nine litters newborn piglets were randomly allocated to three groups: sucking normally (S), weaned at 21 d (W), and early-life FMT + weaned at 21 d (FW). The results demonstrated that differences of fecal microbiota existed in group D and H. Early-life FMT significantly decreased diarrhea incidence of weaned piglets. Intestinal morphology and integrity were improved in the FW group. Both ZO-1 and occludin (tight junction proteins) of jejunum were greatly enhanced, while the zonulin expression was significantly down-regulated through early-life FMT. The expression of IL-6 and TNF-α (intestinal mucosal inflammatory cytokines) were down-regulated, while IL-10 (anti-inflammatory cytokines) was up-regulated by early-life FMT. In addition, early-life FMT increased the variety of the intestinal microbial population and the relative amounts of some beneficial bacteria such as Spirochaetes, Akkermansia, and Alistipes. Functional alteration of the intestinal microbiota revealed that lipid biosynthesis and aminoacyl-tRNA biosynthesis were enriched in the FW group. These findings suggested that alteration of the microbiota network caused by weaning stress induced diarrhea, and early-life FMT alleviated weaning stress in piglets, which was characterized by decreased diarrhea incidence, improved intestinal morphology, reduced intestinal inflammation, and modified intestinal bacterial composition and function

Effects of Cadmium as a Possible Endocrine Disruptor upon the Serum Level of Sex Steroids and the Secretion of Gonadotropins from Pituitary in Adult Rats

Objective: The objective of this study is to assess the effect of cadmium (Cd) upon the female reproductive system by investigating the serum levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH) as well as sex steroids such as estradiol (E2) and progesterone (P). Materials and Methods: Sprague-Dawley (SD) female rats were daily injected subcutaneously with CdCl2 for 7 or 14 days at a dose of 0,0.5 and 1.0 mg /Kg body-weight (BW) and the serum levels of FSH, LH, E2 and P were measured by radioimmunoassay. Also, the levels of FSH and LH in the presence or absence of extraneously added gonadotropin-releasing hormone (GnRH) were determined in the similarly treated rats. Results: Although the FSH and LH levels were not changed by CdCl2 administration, the serum concentration of E2 was significantly decreased by the injection with both high and low doses of CdCl2. In some conditions the serum P level was also decreased. To examine the reactivity of pituitary cells to GnRH in CdCl2 -treated rats, we measured the serum levels of FSH and LH in the presence or absence of extraneously added GnRH and then found that although the secretion of FSH and LH was increased more or less by GnRH administration in any combinations, the increase in the serum LH level of CdCl2 -treated rats was significantly lower than that of control rats. Conclusion: Cd may decrease the reactivity of LH cells to GnRH, resulting in lower serum levels of E2 and P through the disorder of ovarian cycles