Effect of Cyp27A1 gene dosage on atherosclerosis development in ApoE-knockout mice.

In humans, sterol 27-hydroxylase (CYP27A1) deficiency leads to cholesterol deposition in tendons and vasculature. Thus, in addition to its role in bile acid synthesis, where it converts cholesterol to 27-hydroxycholesterol (27-OHC), CYP27A1 may also be atheroprotective. Cyp27A1-deficient (Cyp27A1(-/-)) mice were crossed with apolipoprotein E (apoE)-deficient mice. Cyp27A1(+/+)/apoE(-/-) [ApoE-knockout (KO)], Cyp27A1(+/-)/apoE(-/-) heterozygous (het), and Cyp27A1(-/-)/apoE(-/-) [double-knockout (DKO)] mice were challenged with a Western diet (WD) for 3 and 6 mo. ApoE-KO mice fed a chow diet or a WD were used as the control. The severity of atherosclerosis in DKO mice was reduced 10-fold. Compared with the control, the DKO mice had no 27-OHC, total plasma cholesterol and low-density lipoprotein and very low density lipoprotein (LDL/VLDL) concentrations were reduced 2-fold, and HDL was elevated 2-fold. Expression of hepatic CYP7A1, CYP3A, and CYP8B1 were 5- to 10-fold higher. 3-Hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) activity increased 4-fold. Fecal cholesterol was increased. In contrast, het mice fed a WD developed accelerated atherosclerosis and severe skin lesions, possibly because of reduced reverse cholesterol transport due to diminished 27-OHC production. CYP27A1 activity is involved in the control of cholesterol homeostasis and development of atherosclerosis with a distinct gene dose-dependent effect.

Dietary xenosterols lead to infertility and loss of abdominal adipose tissue in sterolin-deficient mice.

The investigation of the human disease sitosterolemia (MIM 210250) has shed light not only on the pathways by which dietary sterols may traffic but also on how the mammalian body rids itself of cholesterol and defends against xenosterols. Two genes, ABCG5 and ABCG8, located at the sitosterolemia locus, each encodes a membrane-bound ABC half-transporter and constitutes a functional unit whose activity has now been shown to account for biliary and intestinal sterol excretion. Knockout mice deficient in Abcg5 or Abcg8 recapitulate many of the phenotypic features of sitosterolemia. During the course of our studies to characterize these knockout mice, we noted that these mice, raised on normal rodent chow, exhibited infertility as well as loss of abdominal fat. We show that, although sitosterolemia does not lead to any structural defects or to any overt endocrine defects, fertility could be restored if xenosterols are specifically blocked from entry and that the loss of fat is also reversed by a variety of maneuvers that limit xenosterol accumulation. These studies show that xenosterols may have a significant biological impact on normal mammalian physiology and that the Abcg5 or Abcg8 knockout mouse model may prove useful in investigating the role of xenosterols on mammalian physiology.

A Pilot Observational Study Assessing Long-Term Changes in Clinical Parameters, Functional Capacity and Fall Risk of Patients With Chronic Renal Disease Scheduled for Hemodialysis.

BACKGROUND: Patients with end-stage renal disease are known to be particularly frail, and the cause is still widely seen as being directly related to specific factors in renal replacement therapy. However, a closer examination of the transitional phase from predialysis to long-term hemodialysis leads to controversial explanations, considering that the frailty process is already well-described in the early stages of renal insufficiency. This study aims to describe longitudinally and multifactorially changes in the period extending from the decision to start the replacement therapy through to the end of 2 years of hemodialysis. We hypothesized that frailty is pre-existent in the predialysis phase and does not worsen with the beginning of the replacement therapy. Between 2015 and 2018 we recruited 25 patients (72.3 ± 5.7 years old) in a predialysis program, with the expectation that replacement therapy would begin within the coming few months. METHODS: The patients underwent a baseline visit before starting hemodialysis, with 4 follow-up visits in the first 2 years of treatment. Health status, physical performance, cognitive functioning, hematology parameters, and adverse events were monitored during the study period. RESULTS: At baseline, our sample had a high variability with patients ranging from extremely frail to very fit. In the 14 participants that did not drop out of the study, out of 32 clinical and functional measures, a statistically significant worsening was only observed in the Short Physical Performance Battery (SPPB) score (p < 0.01, F = 8.50) and the number of comorbidities (p = 0.01, F = 3.94). A careful analysis, however, reveals a quite stable situation in the first year of replacement therapy, for both frail and fit participants and a deterioration in the second year that in frail participants could lead to death. CONCLUSION: Our results should stimulate a reassessment about the role of a predialysis program in reducing complications during the transitional phase, but also about frailty prevention programs once hemodialysis has begun, for both frail and fit patients, to maintain satisfactory health status.

[Hereditary nephrogenetic diabetes insipidus--case report and discussion]. / Kongenitaler nephrogener Diabetes insipidus--Fallbericht und Diskussion.

The history of a patient with hereditary nephrogenic diabetes insipidus is discussed. The pathogenesis and the therapeutic approach is revised.

Loss of apolipoprotein E exacerbates the neonatal lethality of the Smith-Lemli-Opitz syndrome mouse.

The Smith-Lemli-Opitz syndrome (SLOS) is caused by a genetic defect in cholesterol biosynthesis; mutations in the enzyme 3ss-hydroxysterol Delta7 reductase (Dhcr7) lead to a failure of cholesterol (and desmosterol) synthesis, with an accumulation of precursor sterols, such as 7-dehydrocholesterol. Extensive genotype-phenotype analyses have indicated that there is considerable variation in the severity of the disease, much of which is not explained by defects in the Dhcr7 gene alone. Factors ranging from variations in maternal-fetal cholesterol transfer during pregnancy, to other genetic factors have been proposed to account for this variability. Variations at the APOE locus affect plasma cholesterol levels in humans and this polymorphic gene has been found to be associated with cardiovascular as well as neurological disorders. This locus has recently been implicated in accounting for some of the variations in SLOS. To address whether maternal hypercholesterolemia can affect fetal outcome, we tested the ability of maternal hypercholesterolemia to rescue the neonatal lethality in a mouse model of SLOS. Maternal hypercholesterolemia, induced by ApoE or Ldl-r deficiency not only failed to ameliorate the postnatal lethality, it increased the prenatal mortality of Dhcr7 deficient pups. Thus the murine data suggest that maternal loss of ApoE or Ldl-r function further exacerbates the neonatal lethality, suggesting they may play a role in maternal transfer of cholesterol to the embryo.