Population total and unbound pharmacokinetics and pharmacodynamics of ciprofol and M4 in subjects with various renal functions

AIMS

The aim of this study was to develop a population pharmacokinetic (PK) model to simultaneously describe both total and unbound concentrations of ciprofol and its major glucuronide metabolite, M4, and to link it to the population pharmacodynamics (PD) model in subjects with various renal functions.

METHODS

A total of 401 and 459 pairs of total and unbound plasma concentrations of ciprofol and M4, respectively, as well as 2190 bispectral index (BIS) data from 24 Chinese subjects with various renal functions were available. Covariates that may potentially contribute to the PK and PD variability of ciprofol were screened using a stepwise procedure. The optimal ciprofol induction dosing regimen was determined by model-based simulations.

RESULTS

The PK of unbound ciprofol could best be described by a three-compartment model, while a two-compartment model could adequately describe unbound M4 PK. The concentrations of total and unbound ciprofol and M4 were linked using a linear protein binding model. The relationship between plasma concentrations of ciprofol and BIS data was best described by an inhibitory sigmoidal E_max model with a two-compartment biophase distribution compartment. Hemoglobin was the identified covariate determining the central compartment clearance of ciprofol; uric acid was a covariate affecting the central compartment clearance of M4 and protein binding rate, k_B . The included covariates had no effect on the PD of ciprofol. Simulation results indicated that the label-recommended dose regimen was adequate for anaesthesia induction.

CONCLUSIONS

The developed model fully characterized the population PK and PD profiles of ciprofol. No dose adjustment is required in patients with mild and moderate renal impairment.

Spatial and temporal evolution of climatic factors and its impacts on potential evapotranspiration in Loess Plateau of Northern Shaanxi, China

Agriculture is very sensitive to climate change, and correct forecasting of climate change is a great help to accurate allocation of irrigation water. The use of irrigation water is influenced by crop water demand and precipitation. Potential evapotranspiration (ET₀) is a measure of the ability of the atmosphere to remove water from the surface through the processes of evaporation and transpiration, assuming no control on water supply. It plays an important role in assessing crop water requirements, regional dry-wet conditions, and other factors of water resource management. This study analyzed the spatial and temporal evolution processes and characteristics of major meteorological parameters at 10 stations in the Loess Plateau of northern Shaanxi (LPNS). By using the Mann-Kendall trend test with trend-free pre-whitening and the ArcGIS platform, the potential evapotranspiration of each station was quantified by using the Penman-Monteith equation, and the effects of climatic factors on potential evapotranspiration were assessed by analyzing the contribution rate and sensitivity of the climatic factors. The results showed that the climate in LPNS has become warmer and drier. In terms of the sensitivity of ET₀ to the variation of each climatic factor in LPNS, relative humidity (0.65) had the highest sensitivity, followed by daily maximum temperature, wind speed, sunshine hours, and daily minimum temperature (-0.05). In terms of the contribution rate of each factor to ET₀, daily maximum temperature (5.16%) had the highest value, followed by daily minimum temperature, sunshine hours, relative humidity, and wind speed (1.14%). This study provides a reference for the management of agricultural water resources and for countermeasures to climate change. According to the climate change and the characteristics of the study area, farmers in the region should increase irrigation to guarantee crop water demand.

Application of water footprint combined with a unified virtual crop pattern to evaluate crop water productivity in grain production in China

Water shortages are detrimental to China's grain production while food production consumes a great deal of water causing water crises and ecological impacts. Increasing crop water productivity (CWP) is critical, so China is devoting significant resources to develop water-saving agricultural systems based on crop planning and agricultural water conservation planning. A comprehensive CWP index is necessary for such planning. Existing indices such as water use efficiency (WUE) and irrigation efficiency (IE) have limitations and are not suitable for the comprehensive evaluation of CWP. The water footprint (WF) index, calculated using effective precipitation and local water use, has advantages for CWP evaluation. Due to regional differences in crop patterns making the CWP difficult to compare directly across different regions, a unified virtual crop pattern is needed to calculate the WF. This project calculated and compared the WF of each grain crop and the integrated WFs of grain products with actual and virtual crop patterns in different regions of China for 2010. The results showed that there were significant differences for the WF among different crops in the same area or among different areas for the same crop. Rice had the highest WF at 1.39 m(3)/kg, while corn had the lowest at 0.91 m(3)/kg among the main grain crops. The WF of grain products was 1.25 m(3)/kg in China. Crop patterns had an important impact on WF of grain products because significant differences in WF were found between actual and virtual crop patterns in each region. The CWP level can be determined based on the WF of a virtual crop pattern, thereby helping optimize spatial distribution of crops and develop agricultural water savings to increase CWP.

[Prognostic significance of coagulation disorders in children with hemophagocytic syndrome]

OBJECTIVE

To study the prognostic significance of coagulation disorders in children with hemophagocytic syndrome (HPS).

METHODS

Thirty-five children with HPS were retrospectively studied to analyze the etiology, clinical characteristics, laboratory results and treatment outcomes.

RESULTS

After treatment, 27 of the 35 HPS patients survived, and the other 8 cases died. All cases were treated according to the HLH-2004 protocol, but etoposide (VP-16) was not used in 10 of them. The response rate in patients who received VP-16 (22/25, 88%) was significantly higher than that in those not receiving VP-16 (5/10, 50%) (P<0.05). Compared with the survival group, the dead group had significantly lower platelet count, fibrinogen level, and VP-16 utilization rate (P<0.05) but significantly longer activated partial thromboplastin time and prothrombin time (P<0.05).

CONCLUSIONS

Coagulation function can be used as an indicator of disease outcome. It is essential for improving the clinical outcome of HPS to monitor the coagulation function during treatment, detect and correct abnormalities in time, and provide treatment strictly according to the HLH-2004 protocol.

Inhibition of thymidylate synthase activity by antisense oligodeoxynucleotide and possible role in thymineless treatment

Thymidylate synthase (TS) is an important target for chemotherapeutic treatment of cancer. However, efficacy of TS-targeted anticancer drugs is limited by the development of drug resistance as a result of TS gene amplification. In this work, a phosphorothioated antisense oligonucleotide (ODN), designated ATS-2, was used to suppress cellular synthesis of TS. ATS-2 at 0.2 microM concentration was mixed with lipofectin in a charge ratio of 1:1 and was used to treat the human embryonic kidney (HEK) cell line. A reduction of TS mRNA and protein was achieved. Furthermore, a dose-dependent reduction of cumulative viable cells of up to 98% was observed. Flow cytometer analysis of cell cycle progression indicates that ATS-2-treated cells were arrested and went into apoptosis at the S phase, possibly because of thymidine shortage, suggesting that ATS-2 is specifically effective for dividing cells. When used in combination with the anticancer drug FdUrd, ATS-2 exerted a additive inhibitory effect on cellular proliferation. To elucidate the possible role of cellular thymidine kinase (TdR kinase) in ATS-2 treatment, a second cell line, HeLa, was used. Both HEK and HeLa have similar rates of cell division and ODN uptake. In contrast to HEK, which was shown to have very low levels of TdR kinase activity in [(3)H]thymidine incorporation experiments, [(3)H]thymidine incorporation in HeLa was 15-fold greater than that of HEK. We found that HeLa cells were sensitive to FdUrd but were rather resistant to ATS-2. On the contrary, HEK cells were sensitive to ATS-2 but insensitive to FdUrd. Effects of ATS-2 and FdUrd are, therefore, complementary in thymineless treatment too.