Early Deconditioning of Human Skeletal Muscles and the Effects of a Thigh Cuff Countermeasure

Muscle deconditioning is a major consequence of a wide range of conditions from spaceflight to a sedentary lifestyle, and occurs as a result of muscle inactivity, leading to a rapid decrease in muscle strength, mass, and oxidative capacity. The early changes that appear in the first days of inactivity must be studied to determine effective methods for the prevention of muscle deconditioning. To evaluate the mechanisms of muscle early changes and the vascular effect of a thigh cuff, a five-day dry immersion (DI) experiment was conducted by the French Space Agency at the MEDES Space Clinic (Rangueil, Toulouse). Eighteen healthy males were recruited and divided into a control group and a thigh cuff group, who wore a thigh cuff at 30 mmHg. All participants underwent five days of DI. Prior to and at the end of the DI, the lower limb maximal strength was measured and muscle biopsies were collected from the vastus lateralis muscle. Five days of DI resulted in muscle deconditioning in both groups. The maximal voluntary isometric contraction of knee extension decreased significantly. The muscle fiber cross-sectional area decreased significantly by 21.8%, and the protein balance seems to be impaired, as shown by the reduced activation of the mTOR pathway. Measurements of skinned muscle fibers supported these results and potential changes in oxidative capacity were highlighted by a decrease in PGC1-α levels. The use of the thigh cuff did not prevent muscle deconditioning or impact muscle function. These results suggest that the major effects of muscle deconditioning occur during the first few days of inactivity, and countermeasures against muscle deconditioning should target this time period. These results are also relevant for the understanding of muscle weakness induced by muscle diseases, aging, and patients in intensive care.

AB0266 METHOTREXATE AND CARDIOVASCULAR RISK IN RHEUMATIC DISEASES:A COMPREHENSIVE REVIEW

Background:The management of inflammatory rheumatic disease has evolved in the last decade with the importance of the management of comorbidities. Methotrexate is the cornerstone of inflammatory rheumatic disease management, but its cardiovascular effects are still poorly understoodObjectives:To assess the cardiovascular impact of methotrexate in inflammatory rheumatic disease.Methods:A systematic review of the literature, following the prisma recommandations, was performed on the PubMed and Embase databases with the following keywords: (“Methotrexate”) AND (“cardiovascular”). We included papers written in English and including patients older than 18 years.Results:570 references were identified and, 36 articles were kept for analysis.The mechanism of action of methotrexate lies mainly on the antagonism of purines. It reduces systemic inflammation, oxidative stress.In Rheumatoid arthritis, the use of methotrexate was associated with a decreased incidence of high blood pressure, an improvement of the lipid profile and of the insulin resistance. Major adverse cardiovascular events were decreased with methotrexate. The effects of methotrexate on the endothelial function were more controversial and available data did not argue for a direct vascular effect of MTX in RA.In psoriatic arthritis, evidences were more scarce. A meta-analysis showed that methotrexate was associated with a reduction of cardiovascular events in patients with psoriatic arththritis. In psoriatic arthritis, methotrexate did not improve the endothelial function.In plaque psoriasis, available data were rare. The use of methotrexate in this condition was not associated with a reduction of cardiovascular events. Nevertheless, a decrease in circulating VCAM-1 and in E selectin levels was described with the use of methotrexate.In HIV infection, a model of pro inflammatory state, the use of methotrexate did not change the endothelial function and thus the cardiovascular events.Finally, in general population, the use of methotrexate did not decrease the occurrence of cardiovascular events after a myocardial infarction.Conclusion:The cardiovascular effects of methotrexate are poorly understood at this time. Nevertheless, it seems clear that methotrexate can reduce the occurrence of cardiovascular events in inflammatory disease. The mechanisms explaining this good issue are poorly understood, but it seems possible that the essential effect of methotrexate lies in the reduction of the inflammatory syndrome without a direct vascular impact.Disclosure of Interests:None declared

Inhibition of SGLT-2 rescues bone marrow cell traffic for vascular repair. Role of glucose control and ketogenesis

The mechanisms whereby sodium-glucose cotransporter-2 inhibitors (SGLT2i) improve cardiovascular outcomes in people with diabetes are incompletely understood. Recent studies show that SGLT2i may increase the levels of circulating cells with vascular regenerative capacity, at least in part by lowering glycemia. Here, we used mice with streptozotocin-induced diabetes treated with the SGLT2i dapagliflozin at a dose that reduced glucose levels by ~20%. Dapagliflozin improved the diabetes-associated defect of hematopoietic stem cell mobilization after stimulation with G-CSF. Dapagliflozin rescued the traffic of bone marrow (BM)-derived cells to injured carotid arteries and improved endothelial healing in diabetic mice. Defective homing of CD49d⁺ granulocytes was causally linked with impaired endothelial repair and was reversed by dapagliflozin. The effects of dapagliflozin were mimicked by a similar extent of glucose reduction achieved with insulin therapy, and by a ketone drink that artificially elevated β-hydroxybutyrate. Inhibition of endothelial repair by resident cells using the CXCR4 antagonist AMD3100 did not abolish the vascular effect of dapagliflozin, indirectly supporting that endothelial healing by dapagliflozin was mediated by recruitment of circulating cells. In summary, we show that dapagliflozin improved the traffic of BM-derived hematopoietic cells to the site of vascular injury, providing a hitherto unappreciated mechanism of vascular protection.

Inhibition of SGLT-2 rescues bone marrow cell traffic for vascular repair. Role of glucose control and ketogenesis

The mechanisms whereby sodium-glucose cotransporter-2 inhibitors (SGLT2i) improve cardiovascular outcomes in people with diabetes are incompletely understood. Recent studies show that SGLT2i may increase the levels of circulating cells with vascular regenerative capacity, at least in part by lowering glycemia. Here, we used mice with streptozotocin-induced diabetes treated with the SGLT2i dapagliflozin at a dose that reduced glucose levels by ~20%. Dapagliflozin improved the diabetes-associated defect of hematopoietic stem cell mobilization after stimulation with G-CSF. Dapagliflozin rescued the traffic of bone marrow (BM)-derived cells to injured carotid arteries and improved endothelial healing in diabetic mice. Defective homing of CD49d⁺ granulocytes was causally linked with impaired endothelial repair and was reversed by dapagliflozin. The effects of dapagliflozin were mimicked by a similar extent of glucose reduction achieved with insulin therapy, and by a ketone drink that artificially elevated β-hydroxybutyrate. Inhibition of endothelial repair by resident cells using the CXCR4 antagonist AMD3100 did not abolish the vascular effect of dapagliflozin, indirectly supporting that endothelial healing by dapagliflozin was mediated by recruitment of circulating cells. In summary, we show that dapagliflozin improved the traffic of BM-derived hematopoietic cells to the site of vascular injury, providing a hitherto unappreciated mechanism of vascular protection.

Reduced Flow-Mediated Dilatation Is Not Related to COVID-19 Severity Three Months after Hospitalization for SARS-CoV-2 Infection

The coronavirus disease 2019 (COVID-19) pandemic has spread rapidly worldwide, with more than two million deaths. Evidence indicates the critical role of the vascular endothelium in its pathophysiology but, like potential changes in functional vasodilation, the vascular effect of SARS-CoV-2 at a given distance from the acute infection is largely unknown. We assessed brachial artery flow-mediated dilatation (FMD) in 27 COVID-19 patients needing conventional or intensive care unit hospitalization, three months after SARS-CoV-2 infection diagnosis and in nine age- and sex- matched control subjects. Interestingly, the FMD was lower in COVID-19 patients as compared to controls (8.2 (7.2–8.9) vs. 10.3 (9.1–11.7)); p = 0.002, and half of the hospitalized COVID-19 survivors presented with a reduced FMD < 8% at three months of COVID-19 onset. Impaired FMD was not associated with severe or critical SARS-CoV-2 infection, reflected by ICU hospitalization, total hospitalization duration, or severity of lung damage. In conclusion, reduced FMD is often observed even three months after hospitalization for SARS-CoV-2 infection, but such alteration predominantly appears to not be related to COVID-19 severity. Longer and larger follow-up studies will help to clarify the potential prognosis value of FMD among COVID-19 patients, as well as to further determine the mechanisms involved.

A Novel Vasoactive Peptide “PG1” from Buffalo Ice-Cream Protects from Angiotensin-Evoked High Blood Pressure

Background: Arterial hypertension is the most important risk factor for cardiovascular diseases, myocardial infarction, heart failure, renal failure and peripheral vascular disease. In the last decade, milk-derived bioactive peptides have attracted attention for their beneficial cardiovascular properties. Methods: Here, we combined in vitro chemical assay such as LC-MS/MS analysis of buffalo ice cream, ex vivo vascular studies evaluating endothelial and smooth muscle responses using pressure myograph, and translational assay testing in vivo the vascular actions of PG1 administration in murine models. Results: We demonstrate that a novel buffalo ice-cream-derived pentapeptide “QKEPM”, namely PG1, is a stable peptide that can be obtained at higher concentration after gastro-intestinal digestions (GID) of buffalo ice-cream (BIC). It owns potent vascular effect in counteract the effects of angiotensin II-evoked vasoconstriction and high blood pressure levels. Its effects are mediated by the inhibitory effect on AT1 receptor leading to a downregulation of p-ERK½/Rac1-GTP and consequent reduction of oxidative stress. Conclusions: These results strongly candidate PG1, as a novel bioactive peptide for the prevention and management of hypertension, thus expanding the armamentarium of preventive strategies aimed at reducing the incidence and progression of hypertension and its related cardiovascular complications.

Effects of injectable contraceptives on intraocular pressure among women of child bearing age

Background: The presence of female sex hormones has been linked to variation in intraocular pressure. Numerous studies have revealed that these hormones exert neuroprotective effect and a vascular effect on intraocular pressure regulation. This study was to determine the effect of injectable contraceptives on intraocular pressure in women of child bearing age.Methods: It was a cross-sectional study, carried out at the University of Benin Teaching Hospital involving 85 healthy Nigerian women of child bearing age (20-50 years). The women were divided into two groups 20-35 years (Mean age was 29.66±3.43) and 36-50 years (Mean age 40.66±4.41). A brief case history was conducted to gain information on their personal data, oculo-visual history and general health. Intraocular pressure (IOP) was measured at baseline and two months after injectable contraceptive.Results: There was no statistical significant difference in the IOP reading at baseline and after injectable contraceptives among women in group 20-35 (p=0.819), whereas women in group 36-50 years showed a Statistical significant difference in their IOP at baseline and after injectable contraceptives (p=0.049).Conclusions: Injectable contraceptives have significant effect on IOP of healthy women of childbearing age. Further studies involving a larger sample should be conducted over a long duration in order to achieve a better generalization of the findings on this subject matter.

Subsequent Ultrasound Vascular Targeting Therapy of Hepatocellular Carcinoma Improves the Treatment Efficacy

The response of hepatocellular carcinoma (HCC) to anti-vascular ultrasound therapy (AVUS) can be affected by the inherent differences in tumor vascular structure, and the functionality of tumor vessels at the time of treatment. In this study, we evaluate the hypothesis that repeated subsequent AVUS therapies are a possible approach to overcome these factors and improve the therapeutic efficacy of AVUS. HCC was induced in 30 Wistar rats by oral ingestion of diethylnitrosamine (DEN) for 12 weeks. A total of 24 rats received treatment with low intensity, 2.8 MHz ultrasound with an intravenous injection of microbubbles. Treated rats were divided into three groups: single therapy group (ST), 2-days subsequent therapy group (2DST), and 7-days subsequent therapy group (7DST). A sham control group did not receive ultrasound therapy. Tumor perfusion was measured by quantitative contrast-enhanced ultrasound (CEUS) nonlinear and power-Doppler imaging. Tumors were harvested for histologic evaluation of ultrasound-induced vascular changes. ANOVA was used to compare the percent change of perfusion parameters between the four treatment arms. HCC tumors treated with 2DST showed the largest reduction in tumor perfusion, with 75.3% reduction on average for all perfusion parameters. The ST group showed an average decrease in perfusion of 54.3%. The difference between the two groups was significant p < 0.001. The 7DST group showed a reduction in tumor perfusion of 45.3%, which was significant compared to the 2DST group (p < 0.001) but not different from the ST group (p = 0.2). The use of subsequent targeted AVUS therapies applied shortly (two days) after the first treatment enhanced the anti-vascular effect of ultrasound. This gain, however, was lost for a longer interval (1 week) between the therapies, possibly due to tumor necrosis and loss of tumor viability. These findings suggest that complex interplay between neovascularization and tumor viability plays a critical role in treatment and, therefore, must be actively monitored following treatment by CEUS for optimizing sequential treatment.

Interaction among estrogen, IGF-1, and H2S on smooth muscle cell proliferation

Both estrogen and hydrogen sulfide (H2S) inhibit the proliferation of vascular smooth muscle cells (SMCs) and development of atherosclerosis. In the absence of endogenous H2S as occurred in CSE-knockout (KO) mouse, however, estrogen stimulates the proliferation of vascular SMCs. The underlying mechanisms for this seemingly controversial vascular effect of estrogen are unclear. In the present study, we demonstrated that the stimulatory effect of estrogen on the proliferation of CSE-KO SMCs was suppressed by the inhibitor of insulin-like growth factor-1 receptor (IGF-1R) or knockdown of IGF-1R protein expression. Estrogen downregulated the expression of insulin-like growth factor-1 (IGF-1) and IGF-1R in aortic tissues or aortic SMCs isolated from WT and CSE-KO mice. Furthermore, endogenous H2S downregulated IGF-1R, but upregulated estrogen receptor (ER)-α, in aortic tissues or SMCs. ER-α and IGF-1R were co-located in SMCs and co-immunoprecipitated, which was decreased by H2S. Finally, both endogenous and exogenous H2S induced the S-sulfhydration of IGF-1R, but not ER-α, in WT-SMCs and CSE-KO SMCs, which underlies the decreased formation of IGF-1R/ER-α hybrid in the presence of H2S. Thus, the absence of H2S favors the interaction of estrogen with IGF-1R/ER-α hybrid to stimulate SMCs proliferation. The appreciation of a critical role of H2S in preventing estrogen-induced SMCs proliferation will help better understand the regulation of complex vascular effects of estrogen and sex-related cardiovascular diseases.

Dinamics of skin wound healing with the use of injectable regeneration stimulators in rats

Цель исследования - выявление особенностей динамики заживления кожной раны у экспериментальных крыс зрелого возраста; сравнение эффективности зарегистрированных и применяющихся в клинической практике инъекционных стимуляторов регенерации тканей: депротеинизированного гемодеривата крови телят и коллагена. Методика. Экспериментальное слепое исследование проведено на 9-месячных крысах самцах Wistar массой 443,6±6,5 г. Квадратную рану стандартного размера (каждая сторона 11 мм, глубина раны до фасции, площадь в среднем 123,5±2,1 мм2) наносили на поверхность спины животных. В течение 14 сут изучали эффективность и возможные механизмы действия на заживление кожных ран двух инъекционных лекарственных средств: депротеинизированного гемодеривата крови телят (ДГК, актовегин) и коллагена (Коллост) в сравнении с контролем (физиологический раствор натрия хлорида). В динамике оценивали изменение площади ран, их объема, состояния микрогемоциркуляции. Результаты. Площадь ран группы Контроль сократились к концу 7-х сут в 1,1 раза, 14-х - в 5,0 раза, группы ДГК - в 1,4 и 8,3 раза, группы Коллаген - в 1,5 и 11,9 раза соответственно. В группах Контроль и ДГК заживление ран проходило в горизонтальном направлении, в группе Коллаген - вертикальном. Увеличение площади ран в фазу острого воспаления (в первые 3-5 сут) было только в группах Контроль и ДГК, при которых оно было перпендикулярно линиям напряжения кожи. Это свидетельствует о значимости направлений хирургических разрезов и наложения швов не только при создании, но и при последующем лечении ран. Уровень микроциркуляции в коже, непосредственно примыкающей к краю раны, на 3-и сут увеличивался только в группе ДГК, на 7-е сут - в группе Коллаген, на 14-е сут - во всех ранах всех групп, но наибольшие изменения микрогемоперфузии были в группе Коллаген. Заключение. Установлена эффективность обоих стимуляторов регенерации. Вместе с тем скорость и характер заживления ран при их применении существенно различались, что связано с разными механизмами действия препаратов. Это необходимо учитывать в клинической практике при подборе препаратов для ускорения сроков регенерации раны, уменьшения размеров послеоперационного рубца и повышения его эстетичности. Aim. To characterize the dynamics of skin wound healing in mature experimental rats and to compare the effectiveness of approved clinical injectable stimulants of regeneration (deproteinized hemoderivative of calf blood and collagen). Methods. This experimental blind study was conducted on 9-month-old Wistar male rats weighing 443.6±6.5 g. Square wounds of a standardized size (each side, 11 mm; wound depth, down to fascia; mean area, 123.5 ± 2.1 mm2) were inflicted on the rat back. Efficacy and mechanism of action of two injectable drugs were studied for 14 days. Effects of deproteinized hemoderivative of calf blood (DHB, Actovegin) and collagen (Collost) were compared with control wounds (saline treatment). The wound size and volume and the state of microcirculation were evaluated in dynamics. Results. The area of the wounds decreased by 9.1% at 7 days and 80% at 14 days in the control group; by 28.6% and 88%, respectively, in the DHB group; and by 33.3% and 91.6%, respectively, in the collagen group. In the control and DHA groups, the wound healing was predominantly horizontal while in the collagen group is was vertical. An increase in the wound area in the phase of acute inflammation during the first 3-5 days was observed only in the control and DHB groups; this increase was localized perpendicular to skin tension lines. This indicates the importance of preoperative planning not only for the lines and directions of surgical incisions and suturing but also for the subsequent treatment of wounds. Microcirculation in the skin immediately adjacent to the wound edge increased on day 3 only in the DHB group; in the collagen group, it increased on day 7; and on day 14, it was increased in all wounds of all groups with the greatest vascular effect being observed in the collagen group. Conclusion. Both regeneration stimulants were effective; however, the wound healing patterns and rates were different, which might be due to different mechanisms of action of the drugs. This fact should be taken into account in clinical practice in order to reduce the regeneration time as well as to reduce the size and aesthetics of postoperative scar.