Accumulation of low density lipoprotein associated cholesterol in calcifying vesicle fractions correlates with intimal thickening in thoracic aortas of juvenile rabbits fed a supplemental cholesterol diet

Effects of vitamin D3 supplementation on strength of lower and upper extremities in athletes: an updated systematic review and meta-analysis of randomized controlled trials

Background

Coaches and athletes are increasingly interested in understanding athletes' serum vitamin D levels, their impact on strength, physical performance, and athletic outcomes. Previous meta-analyses were reported with limited sample size and no significant overall effect was found. Hence, it is crucial to conduct a thorough and up-to-date systematic examination and meta-analysis to elucidate the potential advantages of supplementing with vitamin D3 in enhancing muscle strength for athletes.

Methods

We performed a thorough investigation, spanning three databases (PubMed, EBSCO, and Cochrane Library), seeking randomized controlled trials (RCTs) in all languages. These trials delved into the influence of vitamin D3 supplementation on the changes of pre- and post-intervention muscle strength in healthy athletes. Our systematic examination and meta-analysis took into account serum 25(OH)D levels exceeding 30 ng/mL as a marker of adequacy.

Results

Ten RCTs, comprising 354 athletes (185 in the vitamin D3 group and 169 in the placebo group), fulfilled the inclusion criteria. During the study, 36 athletes were lost to follow-up, leaving 318 athletes (166 in the vitamin D3 group and 152 in the placebo group) with documented complete results. In comparison with the placebo group, there is a significant increase between the changes of pre- and post-intervention serum 25(OH)D levels among athletes following a period of vitamin D3 supplementation (MD 14.76, 95% CI: 8.74 to 20.77, p < 0.0001). Overall effect of four strength measurements including handgrip, one repetition maximum Bench Press (1-RM BP), vertical jump, and quadriceps contraction was not significantly improved (SMD 0.18, 95% CI: -0.02 to 0.37, p = 0.08), but there was a significant increase in quadriceps contraction (SMD 0.57, 95% CI: 0.04 to 1.11, p = 0.04).

Conclusion

This updated meta-analysis indicates the potential benefits of vitamin D supplementation for enhancing muscle strength in athletes when analyzing its quantitatively synthesized effects. With limited available studies for the quantitative synthesis, it cannot warrant significant overall enhancements in muscle strength when athletes attain adequate serum 25(OH)D levels through supplementation.

Inhibition of Aortic Calcification by Policosanol in Dyslipidemic Rabbits Is Enhanced by Pentoxifylline

Policosanol (POL) is a hypocholesterolemic drug of natural origin and has been shown to reduce circulating levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) in healthy participants. Recently, we have reported that POL can attenuate aortic calcification in diabetic dyslipidemic rats; however, the underlying mechanism is not fully elucidated. We aimed to investigate the effect of POL on aortic calcification and whether PCSK9 has a contributory role and also to examine whether the combination of POL with pentoxifylline (PTX) as anti–tumor necrosis factor α would offer additional benefits. Thirty adult male New Zealand rabbits weighing 1.5 to 2 kg were randomly assigned to 5 groups. One group received standard chow diet and served as normal control group (NC). The other 4 groups received 0.5% wt/wt cholesterol-rich diet for 12 weeks and concurrently treated with placebo, POL, PTX, or a combination of POL and PTX. Sera samples and aortic tissue were collected for biochemical measurements and histological assessment. Rabbits fed a cholesterol-rich diet demonstrated dyslipidemia, increased inflammatory state, and elevated serum levels of PCSK9, compared to the NC group. Aortic calcification was evident in dyslipidemic rabbits, represented by increased calcium deposition and osteopontin expression in aortic tissue, along with elevated serum levels of alkaline phosphatase and osteocalcin. Dyslipidemic rabbits showed a significant upregulation of wingless-type MMTV integration site family 3A and bone morphogenetic protein 2 genes in their aortic tissue. Policosanol significantly reduced circulating PCSK9 levels, suppressed calcification markers, and attenuated aortic calcification. Combination of POL with PTX alleviated aortic calcification to a greater extent than either monotherapy, which may be attributed to further suppression of PCSK9 and calcification markers. These findings suggested that POL exerted anticalcifying effect partly via inhibition of PCSK9. Combination of POL and PTX offered additional benefits and might represent a promising therapeutic option for aortic calcification.

Sitagliptin ameliorates the progression of atherosclerosis via down regulation of the inflammatory and oxidative pathways

Back ground:

Atherosclerosis is the major cause of death. The most common risk factors are hyperlipidemia, diabetes, and other factors like chronic infection and inflammation.

Objective:

This study was undertaken to assess the effect of sitagliptin on atherosclerosis via interfering with inflammatory and oxidative pathways.

Materials and Methods:

A total of 18 local domestic male rabbits were included in this study. The animals were randomly divided into three groups (6 rabbits in each group): Group I normal were fed with chow (oxiod) diet for 12 weeks. Group II were fed with 1% cholesterol enriched diet for 12 weeks. Group III rabbits fed with cholesterol enriched diet for 6 weeks, and then continued on cholesterol enriched diet and treated with sitagliptin 125 mg/kg/day orally for the next 6 weeks. Blood samples were collected at the start of the study, at 6 weeks of the study and then at the end of treatment to measure serum lipids profile, hsCRP and TNFα. At end of the study, the aorta was removed for measurement of MDA, glutathione and, aortic intima-media thickness.

Results:

Sitagliptin results in a significant reduction (p < 0.05) in serum level of total cholesterol (TC), triglycerides (TG), high sensitive C-reactive protein (hsCRP) and TNFα with a significant increase (p < 0.05) in serum HDL level. There was a significant reduction (p < 0.05) in aortic MDA, in comparison to the untreated control group. Furthermore, sitagliptin causes significant increment (p < 0.05) in aortic GSH in comparison to induced untreated group. Regarding histopathological results, sitagliptin results in a significant reduction (p < 0.05) in atherosclerotic lesions in comparison to the induced untreated group and significant reduction in aortic intima-media thickness (p < 0.05).

Conclusion:

Sitagliptin reduced atherosclerosis progression in hyperlipidemic rabbit via its effect on lipid parameters and interfering with inflammatory and oxidative stress.