Ognen Ivanovski

Uremia Accelerates both Atherosclerosis and Arterial Calcification in Apolipoprotein E Knockout Mice

Chronic renal failure (CRF) favors the development of atherosclerosis and excessive calcification of atheromatous lesions. CRF was induced in apolipoprotein E knockout (apoE(-/-)) mice to study (1) a possible acceleration of aortic atherosclerosis, (2) the degree and type of vascular calcification, and (3) factors involved in the calcification process. For creating CRF, 8-wk-old apolipoprotein E gene knockout (apoE(-/-)) mice underwent partial kidney ablation. Control animals underwent sham operation. Aortic atherosclerotic plaques and calcification were evaluated using quantitative morphologic image processing. At 6 wk after nephrectomy, CRF mice had significantly higher serum urea, cholesterol, and triglyceride concentrations than non-CRF controls. The serum levels of advanced oxidation protein products were elevated in the uremic group and were correlated with serum urea levels. Atherosclerotic lesions in thoracic aorta were significantly larger in uremic apoE(-/-) mice than in nonuremic controls. The relative proportion of calcified area to total surface area of both atherosclerotic lesions and lesion-free vascular tissue was increased in aortic root of uremic apoE(-/-) mice when compared with controls. The calcium deposits were made of hydroxyapatite and calcite crystals. In addition, plaques from uremic animals showed a significant increase in collagen content, whereas the degree of macrophage infiltration was comparable in both groups. There was no difference in mean arterial BP. These findings demonstrate that CRF aggravates atherosclerosis in apoE(-/-) mice. Moreover, CRF enhances arterial calcification at both atheromatous intimal sites and atheroma-free medial sites. We anticipate that this experimental model will be useful to test treatment strategies aimed at decreasing the accelerated atherosclerosis and arterial calcification in uremia.

Sevelamer Prevents Uremia-Enhanced Atherosclerosis Progression in Apolipoprotein E–Deficient Mice

Background— The novel phosphate binder sevelamer has been shown to prevent the progression of aortic and coronary calcification in uremic patients. Whether it also decreases the progression of atheromatous plaques is unknown. The aim of our study was to examine the effect of sevelamer administration on the development of atherosclerosis and aortic calcification in the uremic apolipoprotein E–deficient mouse as an established model of accelerated atherosclerosis. Methods and Results— Female mice were randomly assigned to 4 groups: 2 groups of nonuremic mice (sevelamer versus control) and 2 groups of uremic mice (sevelamer versus control). Sevelamer was given at 3% with chow. The increases in serum phosphorus concentration and calcium-phosphorus product observed in uremic control mice were prevented by sevelamer. Serum total cholesterol was increased in the 2 uremic mouse groups and remained unchanged in response to sevelamer. After 8 weeks of sevelamer treatment, uremic mice exhibited a significantly lower degree of atherosclerosis (P<0.001) and vascular calcification than uremic control mice. Of interest, sevelamer exerted an effect on both intima and media calcification (P=0.005) in uremic mice. Among possible mechanisms involved, we found no evidence for the modulation by sevelamer of inflammation or selected uremic toxins. In contrast, nitrotyrosine staining as a measure of oxidative damage was significantly decreased in response to sevelamer treatment in control and uremic mice (P<0.005). Conclusions— Sevelamer delays not only vascular calcification but also atherosclerotic lesion progression in uremic apolipoprotein E–deficient mice. It opens the possibility of a cholesterol-independent action of sevelamer on atheroma formation via effects on mineral metabolism, oxidative stress, or both.

Fetuin-A Protects against Atherosclerotic Calcification in CKD

Reduced serum levels of the calcification inhibitor fetuin-A associate with increased cardiovascular mortality in dialysis patients. Fetuin-A-deficient mice display calcification of various tissues but notably not of the vasculature. This absence of vascular calcification may result from the protection of an intact endothelium, which becomes severely compromised in the setting of atherosclerosis. To test this hypothesis, we generated fetuin-A/apolipoprotein E (ApoE)-deficient mice and compared them with ApoE-deficient and wild-type mice with regard to atheroma formation and extraosseous calcification. We assigned mice to three treatment groups for 9 wk: (1) Standard diet, (2) high-phosphate diet, or (3) unilateral nephrectomy (causing chronic kidney disease [CKD]) plus high-phosphate diet. Serum urea, phosphate, and parathyroid hormone levels were similar in all genotypes after the interventions. Fetuin-A deficiency did not affect the extent of aortic lipid deposition, neointima formation, and coronary sclerosis observed with ApoE deficiency, but the combination of fetuin-A deficiency, hyperphosphatemia, and CKD led to a 15-fold increase in vascular calcification in this model of atherosclerosis. Fetuin-A deficiency almost exclusively promoted intimal rather than medial calcification of atheromatous lesions. High-phosphate diet and CKD also led to an increase in valvular calcification and aorta-associated apoptosis, with wild-type mice having the least, ApoE-deficient mice intermediate, and fetuin-A/ApoE-deficient mice the most. In addition, the combination of fetuin-A deficiency, high-phosphate diet, and CKD in ApoE-deficient mice greatly enhanced myocardial calcification, whereas the absence of fetuin-A did not affect the incidence of renal calcification. In conclusion, fetuin-A inhibits pathologic calcification in both the soft tissue and vasculature, even in the setting of atherosclerosis.

The outcome of commercial kidney transplant tourism in Pakistan.

Ivanovski N, Masin J, Rambabova‐Busljetic I, Pusevski V, Dohcev S, Ivanovski O, Popov Z. The outcome of commercial kidney transplant tourism in Pakistan.
Clin Transplant 2011: 25: 171–173.

Effect of simvastatin in apolipoprotein E deficient mice with surgically induced chronic renal failure.

PURPOSE Patients with a surgically reduced renal mass are at increased risk for progressive renal failure, which often requires renal replacement therapy or kidney transplantation. We investigated the effects of simvastatin supplementation on uremia enhanced atherosclerosis and vascular calcification in apoE(-/-) (apolipoprotein E deficient) mice (Charles Rivers Laboratories, Wilmington, Massachusetts) with or without superimposed chronic kidney disease. MATERIALS AND METHODS The mice were randomly assigned to 4 groups, including 2 groups with normal renal function (simvastatin vs control in 13 mice) and the other 2 with surgically created chronic kidney disease (simvastatin vs control in 18). Simvastatin (100 mg/kg) was administered by daily oral gavage for 4 weeks. RESULTS Simvastatin treatment did not prevent uremia accelerated atherosclerosis in chronic kidney disease apoE(-/-) mice, nor did it retard atherosclerosis progression in control nonchronic kidney disease mice. However, aortic plaques in simvastatin treated chronic kidney disease mice showed significantly less calcification than those in controls with chronic kidney disease (p <0.03). In addition, the increase of aortic nitrotyrosine staining in mice with chronic kidney disease was prevented by simvastatin treatment (p <0.02). Serum total cholesterol was increased to a similar extent in the 2 chronic kidney disease groups compared with that in the nonchronic kidney disease groups. The beneficial effect of simvastatin on uremia enhanced vascular calcification in apoE(-/-) mice with chronic kidney disease was observed despite the absence of changes in uremia accelerated atherosclerosis progression, serum total cholesterol levels or osteopontin and alkaline phosphatase expression. CONCLUSIONS Our observation opens the possibility of a cholesterol independent action of statins on vascular calcification via a decrease in oxidative stress.

Artificial Penile Bodies—From Kama Sutra to Modern Times

INTRODUCTION Artificial penile nodules are defined as inert objects inserted beneath the skin of the penis to enhance the pleasure of female/male sexual partners during intercourse. AIM The aim of this article is to present our experience in dealing with artificial penile bodies. We have also reviewed the pertinent literature focusing on social, motivational, and occupational characteristics of individuals adopting this sexual practice, diagnostic dilemmas and the surgical and health side effects of the implantation of artificial penile nodules. METHODS We performed a computerized MEDLINE search followed by a manual bibliographic review of cross-references. These reports were analyzed and the important findings summarized. RESULTS The phenomenon of inserting self-made artificial nodules beneath the skin of the penis was first described in the Kama Sutra, the classic Indian treatise on love. It is most commonly observed among men from Southeast Asia. The occurrence is much less common in western cultures, but it has been reported to occur in Romania, Germany, and among Fijians and Russian immigrants in Israel. Furthermore, four cases of self-inserted artificial penile bodies from our clinical practice are presented and discussed. CONCLUSIONS The most common motive associated with foreign artificial bodies on the penis is sexual or erotic in nature and that is to enhance the pleasure of female or male sexual partners during sexual intercourse. Most of the reports involve members of low economic groups like gang members, soldiers, drug addicts, sailors, labor workers, and prisoners. Men suffer no serious side effects after insertion, although fixed beads can cause rupture of condoms. For women, the beads can cause abrasions and a few days of postcoital vaginal pain. Penis implants and inserts and other penis augmentation devices are potentially dangerous to both men and women, and of questionable value in bringing pleasure to either, and should be discouraged.

A new era in the treatment of calcium oxalate stones

Calcium oxalate (CaOx) is the most prevalent type of kidney stone. The amount of oxalate excreted in the urine is a major risk factor for CaOx stone formation. The study by Siener et al. makes a substantial contribution to our understanding of how Oxalobacter formigenes affects oxalate metabolism and excretion in humans and hence influences the risk of developing CaOx kidney stones.

CommentaryA new era in the treatment of calcium oxalate stones

Calcium oxalate (CaOx) is the most prevalent type of kidney stone. The amount of oxalate excreted in the urine is a major risk factor for CaOx stone formation. The study by Siener et al. makes a substantial contribution to our understanding of how Oxalobacter formigenes affects oxalate metabolism and excretion in humans and hence influences the risk of developing CaOx kidney stones.

Cold exposure down-regulates zebrafish pigmentation.

Vertebrates use adaptive mechanisms when exposed to physiologic stresses. However, the mechanisms of pigmentation regulation in response to physiologic stresses largely remain unclear. To address this issue, we developed a novel pigmentation model in adult zebrafish using coldwater exposure (cold zebrafish). When zebrafish were maintained at 17 °C, the pigmentation of their pigment stripes was reduced compared with zebrafish at 26.5 °C (normal zebrafish). In cold zebrafish, gene expression levels of tyrosinase and dopachrome tautomerase, which encode enzymes involved in melanogenesis, were down‐regulated, suggesting that either down‐regulation of melanin synthesis occurred or the number of melanophores decreased. Both regular and electron microscopic observation of zebrafish skin showed that the number of melanophores decreased, whereas aggregation of melanosomes was not changed in cold zebrafish compared with normal zebrafish. Taken together, we here show that cold exposure down‐regulated adult zebrafish pigmentation through decreasing the number of melanophores and propose that the cold zebrafish model is a powerful tool for pigmentation research.

Compared With Radical Nephrectomy, Nephron-sparing Partial Nephrectomy Protects Apolipoprotein E–deficient Mice From Atherosclerosis Progression

OBJECTIVE To compare the effect of radical with partial unilateral nephrectomy on the development of atherosclerosis in the apolipoprotein E (apoE(-/-))-deficient mouse model. METHODS Male apoE(-/-) mice were randomly assigned to the following 3 groups: (1) radical left nephrectomy (RNX, 15 mice), (2) partial left nephrectomy (PNX, 15 mice), and (3) left kidney sham operation (sham-op, 12 mice). The right kidney was left intact in all groups. At 16 weeks after surgery, mice were killed, and atherosclerotic surface area and plaque composition were evaluated in the aortic root and the descending aorta using a quantitative morphologic image processing method. RESULTS At killing, RNX mice had significantly higher serum urea, total cholesterol, and triglyceride concentrations than PNX and sham-op groups (P <.05, P <.001, and P <.0001, respectively). Atherosclerotic lesions in the aortic root and the descending aorta were significantly increased in the RNX mice compared with those in the PNX and sham-op mice (P <.05 and P <.001, respectively). In addition, aortic plaques of RNX mice showed a significant increase in nitrotyrosine expression (P <.02) and collagen content (P <.05), whereas the degree of macrophage infiltration was comparable between the groups. CONCLUSION We show for the first time that PNX, as compared with RNX, slows the progression of vascular disease in a mouse model of severe atherosclerosis. This effect was mediated by the prevention of chronic kidney disease-induced increases in oxidative stress and lipid disturbances. Our finding can be interpreted as being in support of an expanded use of nephron-sparing techniques in atherosclerosis-prone patients who need to undergo kidney cancer surgery.