Vasodilatory effect of hydroxyethyl methacrylate and triethylene glycol dimethacrylate in rat aorta through calcium antagonistic action

Introduction

Resin-based dental materials contain various diluent monomers that can interfere with vascular function by causing vasodilation. In this study, we evaluated the vasoactive potential of hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) and the possible mechanism of their vascular action on isolated rat aorta.

Methods

Responses of thoracic aorta rings were recorded isometrically by using force displacement transducers. After precontracting aorta rings with phenylephrine, relaxations to HEMA and TEGDMA were recorded in the absence and presence of nitric oxide synthase inhibitor N^ω-nitro-L-arginine methyl ester, cyclooxygenase inhibitor indomethacin, and K⁺ channel inhibitors tetraethylammonium, glibenclamide, and 4-aminopyridine. To investigate the Ca²⁺-channel antagonistic effect of HEMA and TEGDMA in different aorta rings, concentration-response curves to CaCl₂ were obtained in the absence and presence of the test monomers.

Results

Both HEMA and TEGDMA elicited concentration-dependent relaxations. The vasorelaxant effect of HEMA and TEGDMA was not mediated via endothelium-dependent nitric oxide and prostanoid-dependent mechanisms or by K⁺ efflux through K⁺ channels. Both monomers significantly inhibited the contractions induced by CaCl₂.

Conclusions

Our results showed that HEMA and TEGDMA induce vasodilation via Ca²⁺-antagonistic action, whereas nitric oxide and cyclooxgenase pathway and K⁺ channels were not responsible for this vasoactive effect.     

Rare Presentation of Pediatric Acute Lymphoblastic Leukemia: Nephromegaly at Time of Diagnosis

Renal involvement is a fairly frequent development in children with acute lymphoblastic leukemia, but palpable renal enlargement at time of diagnosis is very unusual. We report the case of a young girl who presented with enlarged kidneys and was diagnosed with this form of leukemia. This case is of interest because of the rarity of this presentation. The importance of renal biopsy in identifying the etiology of this patient’s nephromegaly is emphasized.     

Sternal wrapping for the prevention of sternal morbidity in elderly osteoporotic patients undergoing median sternotomy

Osteoporosis, a major risk factor for sternum-related morbidity after median sternotomy, is quite prevalent among the elderly. In this prospective study, we investigated the potential of sternal protection by use of the "sternal wrapping method" in elderly osteoporotic patients who were undergoing median sternotomy.For this study, we chose 100 elderly osteoporotic patients who were scheduled to undergo median sternotomy. During surgery, we wrapped the sternal edges with polyvinyl chloride tubing in 50 patients (group 1) and omitted the sternal wrapping in the remaining 50 patients (group 2). We then compared the groups with regard to postoperative pain, bleeding, early and late sternum-related morbidity, sternal fractures, and duration of hospitalization.Sternal wrapping was associated with fewer sternal fractures, less chest pain, and shorter hospital stays. Overall sternal morbidity was significantly less common among patients with sternal wrapping (4% vs. 20%, P = 0.03); however, the difference in individual rates for early and late dehiscence or deep sternal infection did not reach statistical significance.Sternal wrapping using polyvinyl chloride tubes provides mechanical protection and, apparently, less postoperative chest pain and shorter hospitalizations. Probably, it reduces sternum-related complications, particularly in high-risk patients. Its benefits, however, should be confirmed in larger studies.     

Co‐existence of renovascular hypertension,polyarteritis nodosa,antiphospholipid syndrome and methylenetetrahydrofolate reductase mutation

We present a hypertensive child with a co‐existence of polyarteritis nodosa, anti‐phospholipid antibodies (aPL), methylenetetrahydrofolate reductase (MTHFR) mutation and increased lipoprotein a level. Elevated renin, aldosterone and aPL levels, micro‐aneurysms, occlusion and thrombosis at left and right renal artery were found. Anti‐hypertensive agents, prednisolone and pulse cyclophosphamide therapy were started and a stent was inserted in the left renal artery. Two months later, brain magnetic resonance imaging/magnetic resonance imaging angiography showed acute infarct area of the left parietofrontal lobe and middle cerebral artery stenosis. We found bilateral peripheral neuropathy, persistent aPL and elevated Lp(a) level and heterozygous A1298C/MTHFR mutation. Intravenous immunoglobulin and low‐molecular‐weight heparin treatment was added. In conclusion, our observation suggests that in patients with systemic vasculitis, such as polyarteritis nodosa, aPL are probably associated with greater thrombotic risks. The investigation of the LP(a) levels and MTHFR mutations as a synergic pro‐coagulant effect might also be considered for determining patients with vasculitis at risk for severe thrombotic events.