The PRAAVF presented low to moderate primary failure and high primary and secondary patency rates with acceptable complications. Consideration of the specific fistula is required when creating a vascular access, especially when a wrist fistula has failed or is predicted to be unsuccessful.
To analyze the isotonic regression problem for normal means, it is usual to assume that all variances are known or unknown but equal. This paper then studies this problem in the case that there are no conditions imposed on the variances. Suppose that we have data drawn from k independent normal populations with unknown means + i 's and unknown variances _ 2 i 's, in which the means are restricted by a given partial ordering. This paper discusses some properties of the maximum likelihood estimates of + i 's and _ 2 i 's under the restriction and proposes an algorithm for obtaining the estimates.1998 Academic Press
Panax notoginseng is used as a therapeutic agent in Chinese medicine for stopping hemorrhage and also as a general health remedy. Although Panax notoginseng saponins (PNS) are currently attracting attention due to their hemorheological properties, the absorption profiles of PNS have still not been fully investigated. In the present study, an in situ intestinal perfusion rat model was used to investigate the absorption mechanism of sanchinoside R1 (R1) and ginsenoside Rg1 (Rg1), two main components of PNS. Quantitative analysis methods for R1 and Rg1 were first established, then concentrations of R1 and Rg1 in the perfusate were measured in real time through assessment of circulating perfusate in the rat small intestine. The absorption rate constant (k(a)) values for R1 were 0.1223, 0.0946 and 0.0904 h(-1) at a dose of 1, 10 and 100 mg respectively, while those of Rg1 were 0.1169, 0.1134 and 0.1089 h(-1) at a dose of 1, 10 and 100 mg respectively. The optimal absorption site for both of these compounds was found to be the duodenum, which indicated that the bioavailability of the orally administered PNS preparation was relatively low. Finally, the effect of certain absorption promoters on the absorption rates of R1 and Rg1 was investigated. It was found that carbomer and borneol could enhance the permeability of R1 and Rg1 on the intestinal wall (P < 0.05), which indicated that a suitable absorption promoter could improve the absorption of PNS and increase its bioavailability.
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