Analysis of tacrolimus blood concentrations in renal transplant patients.

This study aimed to 1) analyze the results of tacrolimus blood concentration monitored in patients after renal transplantation, 2) observe and establish an optimal therapeutic window for patients, and 3) provide evidence for the clinical and rational use of drugs. Tacrolimus blood concentration was determined by enzyme-linked immunosorbent assay. A total of 1824 cases were obtained from the monitoring of 74 patients after renal transplantation. These cases were then retrospectively analyzed. Over time, the mean whole blood tacrolimus trough concentration after transplantation gradually decreased. This result suggests that the optimal therapeutic windows for patients with renal transplants are as follows: 5 to 20 µg/L at 1 month after surgery; 5 to 15 µg/L at 1-3 months after surgery; 4 to 12 µg/L at 3-6 months after surgery; 4 to 10 µg/L at 6-12 months after surgery; and 3 to 8 µg/L at >12 months after surgery. The absorption of tacrolimus is highly variable. Therefore, tacrolimus concentration in the blood and the recommended clinical therapeutic window should be routinely monitored to adjust the treatment regimen and reduce adverse reactions. In this way, treatment can be optimized.

Preferential loss of dorsal-hippocampus synapses underlies memory impairments provoked by short, multimodal stress.

The cognitive effects of stress are profound, yet it is unknown if the consequences of concurrent multiple stresses on learning and memory differ from those of a single stress of equal intensity and duration. We compared the effects on hippocampus-dependent memory of concurrent, hours-long light, loud noise, jostling and restraint (multimodal stress) with those of restraint or of loud noise alone. We then examined if differences in memory impairment following these two stress types might derive from their differential impact on hippocampal synapses, distinguishing dorsal and ventral hippocampus. Mice exposed to hours-long restraint or loud noise were modestly or minimally impaired in novel object recognition, whereas similar-duration multimodal stress provoked severe deficits. Differences in memory were not explained by differences in plasma corticosterone levels or numbers of Fos-labeled neurons in stress-sensitive hypothalamic neurons. However, although synapses in hippocampal CA3 were impacted by both restraint and multimodal stress, multimodal stress alone reduced synapse numbers severely in dorsal CA1, a region crucial for hippocampus-dependent memory. Ventral CA1 synapses were not significantly affected by either stress modality. Probing the basis of the preferential loss of dorsal synapses after multimodal stress, we found differential patterns of neuronal activation by the two stress types. Cross-correlation matrices, reflecting functional connectivity among activated regions, demonstrated that multimodal stress reduced hippocampal correlations with septum and thalamus and increased correlations with amygdala and BST. Thus, despite similar effects on plasma corticosterone and on hypothalamic stress-sensitive cells, multimodal and restraint stress differ in their activation of brain networks and in their impact on hippocampal synapses. Both of these processes might contribute to amplified memory impairments following short, multimodal stress.

Determination of berberine in Rhizoma coptidis and its preparations by non-aqueous capillary electrophoresis.

A non-aqueous capillary electrophoretic method was established for the determination of berberine in Rhizoma coptidis and its preparations. The effects of organic solvent and the concentrations of sodium acetate were studied, which showed that berberine in extracts of traditional Chinese medicine can be separated successfully in a buffer solution of 75 mmol/L of sodium acetate in methanol containing 1 mol/L of acetic acid. The simple and rapid method was linear in the range 25-200 microgram/mL of berberine and had a good reproducibility, with the relative standard deviation below 2%. Non-aqueous capillary electrophoresis is a satisfactory system for the analysis of alkaloids in traditional Chinese medicine.

Determination of glycyrrhizin in radix glycyrrhizae and its preparations by capillary zone electrophoresis.

A capillary zone electrophoresis method was set up for the separation and determination of glycyrrhizin in Chinese medicinal preparations. Concentrations of Na(2)B(4)O(7) were optimized, which showed that glycyrrhizin in the sample could be separated from interference in the running buffer of 30 mmol/L Na(2)B(4)O(7). Using declofenac as internal standard, the simple method was linear in the range 25-300 microg/mL of glycyrrhizin, and good reproducibility was obtained. The extracts of Radix glycyrrhizae and its preparations could be injected directly for analysis without any pretreatment.

Determination of tetrahydropalmatine in Chinese traditional medicine by nonaqueous capillary electrophoresis.

Tetrahydropalmatine in Rhizoma corydalis and its preparations were separated and determined with no pretreatment in the buffer solution of 50 mmol/L of sodium acetate in methanol containing 2 mol/L acetic acid.

Determination of ferulic acid in Angelica sinensis and Chuanxiong by capillary zone electrophoresis.

Ferulic acid in extracts of raw herbs was separated by capillary zone electrophoresis in the buffer solution of 10 mmol/L Na(2)B(4)O(7). The simple and rapid method was linear, ranging from 5 to 100 microg/mL, and had a good reproducibility with the RSD below 2%. The contents of ferulic acid in Angelica sinensis and Chuanxiong could be easily determined within 15 min with no pretreatment and no interference.

Separation and determination of anthraquinone derivatives in rhubarb and its preparations by micellar electrokinetic capillary chromatography.

A micellar electrokinetic capillary chromatographic method was set up for the quality control of rhubarb and its preparations. Anthraquinone derivatives were separated successfully within 10 min in the buffer solution of 50 mmol/L H3BO3-NaOH (pH 11) containing 25 mmol/L sodium deoxycholate. The established method, with a recovery of extraction of over 90%, has good linear relationship and reproducibility. The contents of anthraquinone derivatives in rhubarb and a tablet of Niu-huang-jie-du differed significantly, showing that the quality control of rhubarb and its preparations is necessary.

The separation of anthraquinone derivatives of rhubarb by miceller electrokinetic capillary chromatography.

A micellar electrokinetic capillary chromatographic method was set up for the separation of five anthraquinone derivatives in rhubarb. Optimization of pH and sodium deoxycholate(SDC) concentrations was studied, which showed that 50 mM H3BO3-NaOH(pH 11) containing 25 mM SDC could separate the five ingredients completely within 10 min with good reproducibility of elution time.

Gas chromatographic determination of mexiletine in human plasma with flame ionization detection after reaction with carbon disulphide.

A gas chromatographic method for the determination of mexiletine in human plasma is described. Mexiletine was simultaneously extracted and derivatized with carbon disulphide for separation and quantitation on a glass column (1.5 m x 3 mm i.d.) packed with 1.5% OV-1 coated on 80-100 mesh Shimalite W (201D). The method required only 0.5 mL of plasma and could detect as little as 10 ng of mexiletine. It has been applied to the study of the pharmacokinetics of mexiletine in healthy volunteers.