Plasma lipoproteins are required for both basal and stress-induced adrenal glucocorticoid synthesis and protection against endotoxemia in mice

Lipoprotein-associated cholesterol has been suggested to make a significant contribution to adrenal steroidogenesis in vivo. To determine whether lipoproteins indeed contribute to optimal adrenal steroidogenesis in mice, in the current study we have determined the effect of relative lipoprotein deficiency on adrenal steroidogenesis in C57BL/6 wild-type mice. Feeding C57BL/6 mice the lipid-lowering drug probucol (0.25% wt/wt) for 2 wk induced a 90% decrease in plasma high-density lipoprotein (HDL) cholesterol levels and a 77% reduction in low-density lipoprotein (LDL) cholesterol levels. Neutral lipid stores were depleted upon probucol treatment specifically in the glucocorticoid-producing zona fasciculata of the adrenal, leading to a 44% decreased plasma corticosterone level under basal conditions. Exposure to lipopolysaccharide (LPS) induced a 37% increase in the adrenal uptake of HDL cholesteryl esters. Probucol-treated mice could induce only a relatively minor corticosterone response upon a LPS challenge compared with controls, which coincided with an approximately twofold increased hepatic expression level of interleukin-6 and tumor necrosis factor (TNF)α and an 89% higher TNFα response in plasma. Furthermore, a compensatory two- to fivefold upregulation of LDL receptor (cholesterol uptake) and HMG-CoA reductase (cholesterol synthesis) expression was noticed in the adrenals of probucol-treated mice. In conclusion, we have shown that lipoprotein deficiency in mice as a result of probucol feeding is associated with decreased adrenal cortex cholesterol levels, a lower basal and stress-induced plasma glucocorticoid level, and an increased susceptibility to LPS-induced inflammation. Therefore, it is suggested that plasma lipoproteins are required for optimal adrenal steroidogenesis and protection against endotoxemia in mice.Biopharmaceutic

Leukocyte ABCA1 remains atheroprotective in splenectomized LDL receptor knockout mice

Biopharmaceutic

Full-thickness scar resection after R1/Rx excised T1 colorectal cancers as an alternative to completion surgery

INTRODUCTION: Local full-thickness resections of the scar (FTRS) after local excision of a T1 colorectal cancer (CRC) with uncertain resection margins is proposed as an alternative strategy to completion surgery (CS), provided that no local intramural residual cancer (LIRC) is found. However, a comparison on long-term oncological outcome between both strategies is missing.METHODS: A large cohort of patients with consecutive T1 CRC between 2000 and 2017 was used. Patients were selected if they underwent a macroscopically complete local excision of a T1 CRC but positive or unassessable (R1/Rx) resection margins at histology and without lymphovascular invasion or poor differentiation. Patients treated with CS or FTRS were compared on the presence of CRC recurrence, a 5-year overall survival, disease-free survival, and metastasis-free survival.RESULTS: Of 3,697 patients with a T1 CRC, 434 met the inclusion criteria (mean age 66 years, 61% men). Three hundred thirty-four patients underwent CS, and 100 patients underwent FTRS. The median follow-up period was 64 months. CRC recurrence was seen in 7 patients who underwent CS (2.2%, 95% CI 0.9%-4.6%) and in 8 patients who underwent FTRS (9.0%, 95% CI 3.9%-17.7%). Disease-free survival was lower in FTRS strategy (96.8% vs 89.9%, P=0.019), but 5 of the 8 FTRS recurrences could be treated with salvage surgery. The metastasis-free survival (CS 96.8% vs FTRS 92.1%, P=0.10) and overall survival (CS 95.6% vs FTRS 94.4%, P=0.55) did not differ significantly between both strategies.DISCUSSION: FTRS after local excision of a T1 CRC with R1/Rx resection margins as a sole risk factor, followed by surveillance and salvage surgery in case of CRC recurrence, could be a valid alternative strategy to CS.Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Low density lipoprotein receptor of macrophages facilitates atherosclerotic lesion information in C57B1/6 mice

Item does not contain fulltext7 p

Relative importance of the LDL receptor and scavenger receptor class B in the beta-VLDL-induced uptake and accumulation of cholesteryl esters by peritoneal macrophages

Contains fulltext : 184623.pdf (Publisher’s version ) (Open Access)9 p

Midazolam is a phenobarbital-like cytochrome p450 inducer in rats

Midazolam is almost exclusively metabolized by cytochrome P450 3A (CYP3A) isoenzymes. Therefore, midazolam is used as a probe to determine CYP3A levels in humans and rats. A prerequisite for longitudinal determination of CYP3A expression levels using midazolam as a probe is that midazolam itself has no effect on the expression of CYP3A. In the present study, we analyzed the mRNA levels and enzyme activities of the major CYP isoforms in the rat liver after intraperitoneal injection of midazolam (50 mg/kg) for 3 consecutive days. CYP3A1 mRNA levels were increased 4-fold in midazolam-treated animals compared with controls, whereas the mRNA levels of CYP3A2, CYP3A9, and CYP3A18 were not altered. The increase in CYP3A1 mRNA was accompanied by a 25% increase in microsomal testosterone 6beta-hydroxylation activity. More strikingly, CYP2B1/2 mRNA levels were increased 22-fold upon midazolam treatment, leading to an 11- to 95-fold enhancement of CYP2B enzyme activity. CYP2C6 mRNA levels were 4 times higher in midazolam-treated animals. Formation of 2alpha-hydroxy-testosterone, mainly catalyzed by CYP2C11, was 2.6-fold lower in liver microsomes from midazolam-treated animals. Midazolam induced CYP2E enzyme activity 2.5-fold at the post-transcriptional level. The induction of CYP2B1/2 mRNA levels by midazolam was dose-dependent (4.5-fold increase at 10 mg/kg). Induction of CYP3A1 and CYP2B expression was also observed in isolated rat hepatocytes cultured with 100 microM midazolam. We conclude that midazolam is a phenobarbital-like CYP inducer in rats. Induction of CYP3A1 by midazolam may have implications for the longitudinal use of midazolam as a probe for analysis of CYP3A expression levels in rats

Selective induction of cytochrome P450 3A1 by dexamethasone in cultured rat hepatocytes: analysis with a novel reverse transcriptase-polymerase chain reaction assay section sign.

The study of drug metabolism in cultured rat hepatocytes is hampered by the rapid loss of the expression of cytochrome P450 enzymes. Nevertheless, the activity of cytochrome P450 3A (CYP3A), one of the most important isoenzymes for drug metabolism, can be elevated by chemical inducers. In the present study, we investigated in cultured rat hepatocytes the induction of all four currently identified CYP3A isoforms by dexamethasone, and compared the results obtained in vitro with the induction profile of dexamethasone in vivo. To this end, CYP3A mRNA levels were quantified with a novel, radioactive reverse transcriptase-polymerase chain reaction (RT-PCR) assay, and CYP3A enzymatic activity was measured by a testosterone hydroxylation assay. In the RT-PCR assay, CYP3A isoforms were co-amplified with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the presence of radioactively labeled nucleotides. This resulted in an extremely sensitive and accurate determination of CYP3A expression levels, relative to those of GAPDH. Using this RT-PCR assay, it was found that the expression of all CYP3A isoforms in rat hepatocytes, cultured on a collagen matrix, was decreased by 80-90% within one day of cultivation. After addition of dexamethasone, at one day after isolation, CYP3A1 mRNA levels were elevated to levels comparable to those in freshly isolated hepatocytes within two days. In contrast, CYP3A2, CYP3A9, and CYP3A18 mRNA levels were not affected by dexamethasone treatment, and were hardly detectable after three days of cultivation. CYP3A enzymatic activity was also induced in cultured hepatocytes (approximately 6-fold) after addition of dexamethasone. In vivo, CYP3A1 mRNA levels increased 45-fold after dexamethasone administration. However, in contrast to the situation in cultured hepatocytes, CYP3A2 and CYP3A18 were also induced, albeit to a lesser extent (4- and 7-fold elevated mRNA levels, respectively). We conclude that the selective induction of CYP3A1 in dexamethasone-treated rat hepatocytes allows the study of biotransformation reactions by CYP3A1, without interference by any of the other CYP3A isoenzymes