Lack of correlation between coronary artery calcium and myocardial perfusion imaging

BACKGROUND: Coronary artery calcium (CAC) provides evidence of coronary atherosclerosis and has significant prognostic power. Although prior studies have documented a relationship between CAC and hemodynamically significant coronary artery stenosis, the results have not been conclusive. METHODS AND RESULTS: We evaluated 126 consecutive patients who underwent electron beam computed tomography CAC scoring by use of the Agatston method and stress myocardial perfusion imaging (MPI) within 3 months of each other. The analysis revealed no correlation between absolute CAC score and age- and gender-adjusted CAC scores with MPI. Overall, 18% of patients had abnormal MPI results irrespective of their CAC. CONCLUSION: CAC scoring and stress MPI should be thus considered complementary approaches rather than exclusionary in the evaluation of the patient at risk for coronary artery disease.     

普鲁卡因选择性涂丝电极稳定性的研究

涂丝电极的应用已很广泛,但其稳定性差限制了它的进一步推广应用。本文找出普鲁卡因涂丝电极稳定性差的原因,制备了以聚乙烯醇(含盐酸普鲁卡因)为内参的Ag-Agcl丝涂(PVC)膜电极,其稳定性大为提高,并有良好的响应性能。     

Biosynthesis and secretion of factor VII, protein C, protein S, and the Protein C inhibitor from a human hepatoma cell line

Using specific radioimmunoassays, 8 day cultures of Hep G2 cells were shown to contain in their supernatants 16, 74, and 828 ng/mL and in their cell lysates, 8, 55, and 48 ng/2 X 10(8) cells of factor VII, protein C, and protein S, respectively. These proteins and the protein C inhibitor were functionally active, and each of these activities was neutralized by their respective polyclonal antibodies. Although vitamin K had a modest effect, warfarin decreased the activity of secreted factor VII, protein C, and protein S by 50% to 90%. Protein C and protein S antigens were reduced three- to fourfold by warfarin. The protein C inhibitor antigen and activity were unaffected by vitamin K or warfarin treatment. Intrinsic labeling and immunoprecipitation indicated that factor VII, protein S, and the protein C inhibitor were secreted as 52,000, 77,000, and 58,000 molecular weight (mol wt) proteins, respectively. Protein C was secreted as a single-chain protein of about 65,000 mol wt, indicating that all of the vitamin K- dependent proteins are translated and secreted as single-chain molecules. Each of the four proteins studied represented their plasma protein counterparts structurally, functionally, and immunochemically. Thus, all of the known soluble components of the protein C pathway are produced by liver parenchymal cells.     

Renal Reserve Filtration Capacity in Patients With Type 1 (Insulin-Dependent) Diabetes Mellitus

Glomerular hyperfiltration is one of the factors held responsiblefor the development of diabetic nephropathy. A supranormal glomerularfiltration rate (GFR) can be found in diabetic patients evenwhen they are well controlled. Infusion of low-dose dopaminedemonstrates that glomerular hyperfiltration in well-controlledinsulin-dependent diabetic patients is not based on a predominantvasodilatation of the efferent arteriole. In the present studythis is confirmed, since the dopamine-induced rise in GFR ofcontrol subjects (13.5%±2.2) did not differ from thatof patients with insulin-dependent diabetes mellitus (10.8%±2.1).In animal studies it has been demonstrated that the increasedGFR in diabetes mellitus is caused by a predominant decreasein resistance of the afferent arteriole. Protein loading andinfusion of amino acids also increase GFR by dilatation of theafferent arteriole. Thus, protein loading or amino acid infusionmay be used to test the existence of afferent vasodilatation.The present study investigates the effect of amino acid infusionon GFR of control subjects and insulin-dependent diabetic subjects.The amino acid-induced rise in GFR tended to be lower in thediabetic patients (6.9%±2.8) compared with controls (13.2%±2.7).Percentage amino acid-induced change in GFR appeared to declinewith increasing baseline GFR in the diabetic subjects (r=–0.83;P<0.001). In controls, no such relationship was established(r=–0.22; n.s.). Our results suggest the existence ofafferent vasodilatation in diabetic patients with a high GFR.The cause of this vasodilatation warrants further study.     

唐松草新碱水溶液的氧化降解动力学研究

本文研究了唐松草新碱在水溶液中的氧化降解动力学。考查了pH值、离子强度、温度和氧含量的影响,水溶液中的氧化降解速率常数由荧光法测定。结果表明,唐松草新碱在过量氧存在下,其氧化降解反应服从假一级反应动力学方程式,速率常数可由下式表示:其速率常数主要受介质的pH值和氧含量的影响,在pH 7.2条件下没有观测到原盐效应。     

Effect of intravenous infusion of low-dose dopamine on renal function in normal individuals and in patients with renal disease

A low dose of dopamine was infused in 28 normal volunteers and in 137 patients with varying degrees of renal insufficiency during a routine measurement of the glomerular filtration (GFR) and the effective renal plasma flow (ERPF). Dopamine infusion led to an increase in ERPF and GFR and to fall in the filtration fraction. The effect of dopamine on renal function was most pronounced if the baseline GFR was normal. However, healthy individuals showed greater increases in both ERPF and GFR than renal patients with a comparable baseline GFR. In renal patients no effect was observed if the baseline GFR was below 50 ml/min/1.73 m2. Firstly, it is concluded that already early in renal disease there exists a diminished reserve filtration capacity. Secondly, if the GFR is less than 50 ml/min/1.73 m2, the renal reserve filtration capacity seems to be exhausted.     

Successful transition to buprenorphine in a patient with methadone-induced torsades de pointes

A 56-year-old-man presented with syncope and torsades de pointes secondary to methadone-induced QT prolongation. After transition from methadone to buprenorphine, a partial μ-opiate-receptor agonist and a κ-opiate-receptor antagonist, the QT normalized and ventricular arrhythmias resolved. Buprenorphine should be used for opiate dependence and chronic pain in patients with methadone-induced QT prolongation and as first line therapy in patients with risk factors for torsades de pointes. The authors have no conflicts of interest or financial disclosures.