Dietary l-Lysine Prevents Arterial Calcification in Adenine-Induced Uremic Rats

Vascular calcification (VC) is a life-threatening complication of CKD. Severe protein restriction causes a shortage of essential amino acids, and exacerbates VC in rats. Therefore, we investigated the effects of dietary l-lysine, the first-limiting amino acid of cereal grains, on VC. Male Sprague-Dawley rats at age 13 weeks were divided randomly into four groups: low-protein (LP) diet (group LP), LP diet+adenine (group Ade), LP diet+adenine+glycine (group Gly) as a control amino acid group, and LP diet+adenine+l-lysine·HCl (group Lys). At age 18 weeks, group LP had no VC, whereas groups Ade and Gly had comparable levels of severe VC. l-Lysine supplementation almost completely ameliorated VC. Physical parameters and serum creatinine, urea nitrogen, and phosphate did not differ among groups Ade, Gly, and Lys. Notably, serum calcium in group Lys was slightly but significantly higher than in groups Ade and Gly. Dietary l-lysine strongly suppressed plasma intact parathyroid hormone in adenine rats and supported a proper bone-vascular axis. The conserved orientation of the femoral apatite in group Lys also evidenced the bone-protective effects of l-lysine. Dietary l-lysine elevated plasma alanine, proline, arginine, and homoarginine but not lysine. Analyses in vitro demonstrated that alanine and proline inhibit apoptosis of cultured vascular smooth muscle cells, and that arginine and homoarginine attenuate mineral precipitations in a supersaturated calcium/phosphate solution. In conclusion, dietary supplementation of l-lysine ameliorated VC by modifying key pathways that exacerbate VC.Medial vascular calcification is common in aging, diabetes, and CKD.^1–4 Because the presence of vascular calcification is strongly associated with increased cardiovascular morbidity and mortality, several studies in both animals and humans have sought ways to reduce the extent of vascular calcification.^5–10 However, satisfactory therapies have not yet been established.¹¹Adenine-induced renal failure is one of the commonly used animal models for studying the development of vascular calcification, but the prevalence of vascular calcification in this model is not very high. Indeed, Price et al. reported that vascular calcification was detected in only 30% of rats with adenine-induced chronic renal failure (adenine rats) fed a normal-protein diet.⁵ These authors speculated that consistent vascular calcification might require a longer period of adenine feeding. On the basis of this idea, they designed a low-protein (LP) diet in an attempt to reduce the nitrogen load and thus enable the rats to thrive on the adenine diet for longer periods. As a result of this attempt, Price et al. unexpectedly found that adenine rats fed a LP diet had extensive vascular calcification without a longer feeding period.⁵ All 13 adenine rats fed the LP diet had uniform alizarin red staining of the aorta, whereas only 3 of the 11 adenine rats fed a normal-protein diet had partial calcification.⁵ These findings indicated that dietary protein deficiency correlates with the extent of vascular calcification.Proteins are usually made from 20 kinds of amino acids. On the basis of nutritional requirements, these amino acids can be divided into two groups: essential amino acids (EAAs) and non-EAAs. Because restriction of dietary protein results in a shortage of EAAs, the level of dietary EAAs may be relevant to the extent of vascular calcification. Among nine EAAs, this study focused on l-lysine (l-Lys) based on the following three reasons. First, l-Lys is the first-limiting amino acid in most cereal grains.¹² Second, the safety of l-Lys supplementation has been verified in the area of animal husbandry. l-Lys has long been added to feed grains in order to improve the utility of feed proteins.¹³ Third, several studies have demonstrated that dietary supplementation with l-Lys protects bones from osteoporosis, a pathologic condition that often coexists with vascular calcification.^14,15 These points prompted us to hypothesize that supplementation with l-Lys would ameliorate vascular calcification. Therefore, in this study, we tested this hypothesis using adenine rats.     

CT portography by multidetector helical CT: comparison of three rendering models

PURPOSE: To assess the value of multidetector CT portography in visualizing varices and portosystemic collaterals in comparison with conventional portography, and to compare the visualizations obtained by three rendering models (volume rendering, VR; minimum intensity projection, MIP; and shaded surface display, SSD). METHODS: A total of 46 patients with portal hypertension were examined by CT and conventional portography for evaluation of portosystemic collaterals. CT portography was performed by multidetector CT (MD-CT) scanner with a slice thickness of 2.5 mm and table feed of 7.5 mm. Three types of CT portographic models were generated and compared with transarterial portography. RESULTS: Among the 46 patients, 48 collaterals were identified on CT transverse images, while 38 collaterals were detected on transarterial portography. Forty-four of 48 collaterals identified on CT transverse images were visualized with the MIP model, while 34 and 29 collaterals were visualized by the VR and SSD methods, respectively. The average CT value for the portal vein and varices was 198 HU with data acquisition of 50 sec after contrast material injection. CONCLUSIONS: CT portography by multidetector CT provides excellent images in the visualization of portosystemic collaterals. The images of collaterals produced by MD-CT are superior to those of transarterial portography. Among the three rendering techniques, MIP provides the best visualization of portosystemic collaterals.     

Adjacent segment disease after anterior cervical interbody fusion

BACKGROUND CONTEXT: There have been many follow-up studies on anterior interbody fusion for cervical nerve root and spinal cord compression, and excellent neurological outcomes have been reported. However, postoperative degenerative changes at adjacent discs may lead to the development of new radiculopathy or myelopathy. In the previous reports, the incidence of symptomatic adjacent segment disease has ranged from 7% to 15%. PURPOSE: The present study was undertaken to investigate the incidence of symptomatic adjacent segment disease after anterior cervical interbody fusion (ACIF) and to identify the factors that are related to the development of this disease. STUDY DESIGN/SETTING: This is a retrospective cohort study. PATIENT SAMPLE: A total of 112 patients were followed up clinically and radiologically for more than 2 years. OUTCOME MEASURES: Follow-up evaluation was primarily by means of clinical visits. The postoperative course of any symptoms, the findings of neurological examination and serial follow-up radiographs were performed in all patients. METHODS: The diagnosis of symptomatic adjacent segment disease was based on the presence of new radiculopathy or myelopathy symptoms referable to an adjacent level, and the presence of a compressive lesion at an adjacent level by magnetic resonance imaging or myelography. We evaluated the correlation between the incidence of symptomatic adjacent segment disease and the following clinical parameters (age at operation, sex, number of the levels fused) and radiological parameters (preoperative cervical spine alignment, preoperative range of motion of C2-C7 cervical spine, anteroposterior spinal canal diameter, preoperative existence of an adjacent segment degeneration on plain radiograph, myelography and magnetic resonance imaging [MRI]). RESULTS: Symptomatic adjacent segment disease developed in 19 of 112 patients (19%) followed. A Kaplan-Meier survival analysis was performed in order to follow the disease-free survival of the entire series of patients. The disease-free survival rates were 89% at 5 years, 84% at 10 years and 67% at 17 years. The incidences of indentation of dura matter on preoperative myelography or disc protrusion on MRI at the adjacent level were significantly higher in disease cases (p=.0087, .0299, respectively; chi-squared test). However, the other parameters did not show a statistically significant difference. There were seven cases (37%) who had failure of nonoperative treatment and additional operations were performed. CONCLUSIONS: The incidence of symptomatic adjacent segment disease after ACIF was higher when preoperative myelography or MRI revealed asymptomatic disc degeneration at that level regardless of the number of the levels fused, preoperative alignment, spinal canal diameter or fusion alignment.     

Aortic root replacement with a freestyle stentless valve for aortitis syndrome with ascending aortic aneurysm and aortic regurgitation.

A 47-year-old woman who had been diagnosed as having aortitis syndrome underwent aortic root replacement for an ascending aortic aneurysm and aortic regurgitation. Because the patient has been treated with steroids for more than 20 years, a Freestyle stentless valve was used to avoid the risk of valve detachment. There were no complications observed during the postoperative course. Although long-term follow-up will be necessary to observe the valve durability, the Freestyle stentless valve seems to be useful for aortic root replacement in patients at high risk of valve detachment due to aortitis syndrome.     

Surgical repair of a common atrium in an adult.

We report a rare successful surgical repair of a common atrium (CA) with mild tricuspid valve (TV) regurgitation due to valvular annulus enlargement in a 39-year-old man, who had a complete atrial septum defect (ASD) without the characteristic of an endocardial cushion defect. The left-to-right shunt ratio was 85 percent and the Qp/Qs was 6.7 due to the CA. Left ventriculogram revealed no evidence of typical goose-neck deformity and no mitral valve regurgitation. The operation consisted of making a new atrial septum with an autologous pericardial patch and tricuspid annuloplasty (DeVega) using extracorporeal circulation. There was no evidence of a cleft on the anterior leaflet of the mitral valve or the septal leaflet of the TV. The postoperative echocardiogram showed no residual shunt flow through a new atrial septum and no TV regurgitation, and atrioventricular (AV) dissociation did not occur. We consider this procedure to be widely applicable in consideration of the favorable results obtained after surgical treatment.     

Computer-aided detection of lung nodules on multidetector row computed tomography using three-dimensional analysis of nodule candidates and their surroundings

Purpose  We have been developing a computer-aided detection (CAD) system for lung nodules on multidetector row computed tomography (MDCT). The scheme for nodule detection in this system is featured by three-dimensional analysis for nodule detection in nodules and their surroundings, which is designed to discriminate nodules from blood vessels. The purpose of this study was to evaluate the CAD system. Materials and methods  MDCT images from 30 patients with lung nodules were read twice, 3 weeks apart by a chest radiologist to detect noncalcified nodules of ≥4 mm. The first reading was without CAD, and the second reading was with CAD. Based on the reference standard later determined by another chest radiologist, the sensitivity of the former chest radiologist without or with CAD was obtained; the sensitivity and false-positive rate of the system alone were also obtained. Results  The reference standard consisted of 66 nodules. The sensitivity of the chest radiologist was 77% (51/66) without CAD and 91% (60/66) with CAD, showing a significant improvement. The CAD system alone showed a sensitivity of 79% (52/66) with the false-positive rate of 4.5 per patient. Conclusion  Although preliminary, these results indicate the efficacy of the CAD system.     

Radiation dose reduction in chest CT: a review

OBJECTIVE: This article aims to summarize the available data on reducing radiation dose exposure in routine chest CT protocols. First, the general aspects of radiation dose in CT and radiation risk are discussed, followed by the effect of changing parameters on image quality. Finally, the results of previous radiation dose reduction studies are reviewed, and important information contributing to radiation dose reduction will be shared. CONCLUSION: A variety of methods and techniques for radiation dose reduction should be used to ensure that radiation exposure is kept as low as is reasonably achievable.     

Spontaneous and isolated dissection of the main trunk of the superior mesenteric artery.

A 42-year-old man was admitted to another hospital complaining of acute abdominal pain that was induced by eating. Abdominal computed tomography and selective angiography revealed an intimal flap separating true and false lumens that was located 3 cm from the origin of the superior mesenteric artery (SMA). Emergency surgery was performed because of the sudden recurrence of diffuse abdominal pain after eating and abdominal aorta-SMA bypass grafting was done using a radial artery graft. Postoperative angiography revealed that the graft showed good patency. The postoperative course was uneventful and abdominal pain no longer occurred after eating. This excellent result was achieved by early diagnosis using CT scanning and angiography plus an aggressive surgical repair with a radial artery bypass graft for isolated dissection of the superior mesenteric artery.