Estimated glomerular filtration rate progression in UK primary care patients with type 2 diabetes and diabetic kidney disease: a retrospective cohort study.

AIMS: To examine the rates of diabetic kidney disease (DKD) progression and associated factors, we undertook a study of estimated glomerular filtration rate (eGFR) in a historical cohort of UK primary care patients with type 2 diabetes mellitus (T2DM) and associated DKD from the Clinical Practice Research Datalink. METHODS: Our eligible population were patients with definitive T2DM from a recorded diagnostic code with either a diagnosis of chronic kidney disease (CKD) or renal function test values and renal abnormalities consistent with a CKD diagnosis, identified between 1 October 2006 and 31 December 2011. Only patients with albuminuria results reported in mg/l were used for the longitudinal statistical analyses of the eGFR rate of change using multilevel models. RESULTS: We identified 111,030 patients with T2DM. Among them 58.6% (95% confidence interval (CI): 58.3-58.9) had CKD and 37.2% (95% CI: 36.9-37.5%) had presumed DKD at baseline. Only 19.4% of patients had urinary albumin test results expressed as mg/l in the year prior to index date. Almost two-thirds (63.8%) of patients with T2DM and presumed DKD received prescriptions for angiotensin-converting enzyme (ACE) inhibitors or angiotensin type 1 receptor blockers (ARB) or both. Time-dependent variables that predict subsequent eGFR decline include increased albuminuria, time from index date and older age. CONCLUSION: Only a minority of diabetic patients with DKD had quantitative albuminuria assessments. The relatively low proportion of DKD patients with ACEi or ARB prescriptions suggests a gap between healthcare practice and available scientific evidence during the study period. Increased albuminuria and older age were the most consistent predictors of subsequent eGFR decline.

MDL 29311. Antioxidant with marked lipid- and glucose-lowering activity in diabetic rats and mice.

MDL 29311, an analogue of probucol, administered to rats as a 1% dietary admixture for 2 wk before and 5 days after intravenous injection of 40 mg/kg of ALX significantly (P < 0.05) reduced plasma glucose (6.9 +/- 0.3 vs. 19.2 +/- 1.3 mM) and serum triglyceride (0.17 +/- 0.01 vs. 1.82 +/- 0.39 mM) levels in overnight-fasted ALX-plus-MDL 29311-administered rats vs. ALX-administered rats. A cross-over study indicated that MDL 29311 did not attenuate the diabetogenic action of ALX, but rather, directly lowered glucose and triglycerides. In rats injected intravenously with 45, 65, or 85 mg/kg of STZ and then administered control or MDL 29311 diet for 7 days, MDL 29311 decreased fasted plasma glucose to nondiabetic levels, decreased fasted and nonfasted plasma triglycerides by 49-79%, but did not affect plasma insulin levels. In STZ-induced (65 mg/kg) diabetic rats, MDL 29311 attenuated the increase in plasma nonesterified fatty acids during an 18-h fast; had little or no effect on glucagon, pyruvate, lactate, beta-hydroxybutyrate, acetoacetate, or cholesterol; and did not induce hypoglycemia in rats fasted up to 64 h. In nonfasted hyperinsulinemic db/db mice treated for 10 wk, MDL 29311 significantly lowered glucose levels by 14-40%, triglyceride levels by 31-63% and GHb from 8.0 to 5.4%, and had no consistent effect on plasma insulin levels. Because of its marked glucose- and lipid-lowering activity in both nonfasted hyperinsulinemic and fasted insulinopenic animals, MDL 29311 merits additional investigation as a potential antidiabetic agent.

MDL 29311, an analog of probucol, decreases triglycerides in rats by increasing hepatic clearance of very-low-density lipoprotein.

MDL 29311 is an analog of probucol that shares probucol's antioxidant and antiatherogenic properties. When fed to rats as a 1% dietary admixture, MDL 29311 decreased triglyceride levels by 65% without affecting total or high-density lipoprotein (HDL) cholesterol levels. Under the same conditions, probucol decreased triglyceride levels by 23% and total cholesterol levels by 29% (with a corresponding decrease in HDL cholesterol level). MDL 29311 treatment did not affect the rate of triglyceride entry into the plasma. However, MDL 29311-treated rats cleared in vivo-labeled very-low-density lipoprotein (VLDL)-associated [3H]-triglyceride ([3H]-VLDL) over threefold faster than control rats. This increase in clearance led to increased levels of [3H]-lipid in liver and decreased [3H]-lipid in fat, muscle, diaphragm, and kidney of MDL 29311-treated rats 1.5 to 2.0 minutes after injection of [3H]-VLDL. MDL 29311 treatment had no effect on lipoprotein lipase (LPL) or hepatic triglyceride lipase (H-TGL) activities, or on plasma apolipoprotein (apo) C-II-dependent LPL activation. Intravenously injected [3H]-VLDL was allowed to circulate in MDL 29311-treated or control rats for 1 minute, and the undiluted plasma was then perfused through rat livers in a recirculating system. The [3H] in MDL 29311 plasma was cleared threefold faster (t1/2, 1.3 v 3.8 minutes) than the [3H] in control plasma by control livers. Conversely, the [3H] in control plasma was cleared slowly (t1/2 = 3.5 minutes) by the livers of MDL 29311-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Splenomegaly in dogs. Predictors of neoplasia and survival after splenectomy.

Splenomegaly confirmed by surgery or necropsy in 100 dogs was diagnosed histologically as benign neoplasia (n = 1), primary splenic malignancy (n = 59), neoplastic metastases (n = 6), and nonneoplastic disease (n = 34). Dogs with known systemic disease, such as lymphoma and mast cell tumor, that caused splenomegaly were not included in the study. Hemangiosarcoma was the most common splenic disease (43 cases). Overall mean age of the dogs was 10.7 years, the most common breed was German Shepherd dog, and 72 of the dogs weighed more than 21 kg. Dogs with anemia, nucleated red blood cells, abnormal red blood cell morphology, or splenic rupture had a significantly greater chance of having splenic neoplasia (P less than 0.002). A multivariable logistic regression analysis found that the presence of anemia and splenic rupture in dogs with splenomegaly was up to 69% accurate in predicting presence of splenic neoplasia. After splenectomy, the median survival time of dogs with splenic neoplasia was 13 weeks. For dogs with nonneoplastic splenomegaly it was at least 36 weeks.

Sustained moderate visual loss as a predictive end point for visual loss in non-proliferative diabetic retinopathy.

PURPOSE: In PKC-DRS2, the efficacy of the oral PKC-beta inhibitor, ruboxistaurin 32 mg/day, was measured by the primary end point of sustained moderate visual loss (SMVL: a > or = 15 letter decrease from baseline on the ETDRS (Early Treatment Diabetic Retinopathy Study) chart sustained at least for the last 6 months of study participation). We now evaluate whether SMVL is more accurate than moderate visual loss (MVL: a single occurrence of a decrease from baseline of > or = 15 ETDRS letters) for predicting future visual loss. METHODS: Study eyes with moderately severe to very-severe non-proliferative diabetic retinopathy, best-corrected visual acuity of at least 45 letters on the ETDRS chart (approximately Snellen 20/125), and no prior pan retinal photocoagulation were evaluated in 506 patients (869 eyes) who completed 36 months of treatment. RESULTS: Sixty-five percentage (26/40) of study eyes with the onset of SMVL within 24 months of enrolment still had SMVL at study completion (36 months). In comparison, only 24% (30/126) with MVL within 24 months had SMVL at study completion. Analyses based on data from 6, 12, and 18 months of treatment were similar. CONCLUSIONS: SMVL is a more predictable measure of subsequent visual loss than is a single time point measure of MVL.

MDL 29311, a phenolic antioxidant, interferes with the interaction of apoC with VLDL: a possible explanation for its triglyceride-lowering effect.

MDL 29311 is an antioxidant that lowers plasma triglycerides and raises high density lipoprotein (HDL) cholesterol in rats. It lowers triglycerides in rats by enhancing the clearance of very low density lipoprotein (VLDL) by the liver (Sheetz, M. J., et al. 1994. Metabolism. 43: 232-240). In this paper, the possibility that MDL 29311 enhances VLDL clearance by altering the apolipoprotein (apo) content of lipoproteins is examined. Treatment of rats with 1% MDL 29311 in the diet for 7 days lowered plasma triglycerides and markedly increased total lipoprotein-associated apoE. The increase in apoE was confined to the HDL fraction; no increase in VLDL-associated apoE was detected. No apparent alterations in the amount of total lipoprotein-associated apoC were observed, although there was a decrease in VLDL-associated apoC-II and C-III-0. Consistent with this finding, the amount of 125I-labeled apoC transferred from HDL to VLDL in plasma from MDL 29311-treated rats was only 40% of the amount transferred in control plasma. Sepharose 6B gel filtration of mixtures of 125I-labeled apoC with increasing concentrations of MDL 29311 in the absence of plasma or lipid revealed that proportionally increasing amounts of the 125I-labeled apoC eluted in a high molecular weight (HMW) complex with MDL 29311. An HMW complex was not formed when MDL 29311 was mixed with 125I-labeled soybean trypsin inhibitor. The 125I-labeled apoC in the HMW complex bound to VLDL only 20% as well as uncomplexed 125I-labeled apoC. MDL 29311 also caused the dissociation of 125I-labeled apoC from VLDL at concentrations of MDL 29311 similar to those obtained in vivo. Other phenolic antioxidants related to MDL 29311 caused the formation of HMW 125I-labeled apoC-containing complexes to an extent proportional to their abilities to lower triglycerides in rats. These studies support the hypothesis that MDL 29311 lowers triglycerides in rats by interfering with apoC association with VLDL, thereby relieving the apoC-mediated inhibition of hepatic VLDL uptake.

The role of protein kinase C in the development of the complications of diabetes.

Diabetes mellitus produces a state of chronic hyperglycemia which in turn leads to the development of severe complications including retinopathy, nephropathy, neuropathy, and atherosclerosis. Many different mechanisms have been put forward to attempt to explain how glucose elevations can damage these various organ systems. Protein kinase C activation is one of the sequelae of hyperglycemia and is thought to play a role in the development of diabetic complications. There are multiple mechanisms for its activation in the diabetic state and multiple downstream effects attributable to that activation. The role of protein kinase C activation in the development of the above-mentioned complications of diabetes is discussed in this chapter. In addition, the potential use of isoform-specific inhibitors of protein kinase C for the treatment of diabetic complications is proposed.

Receptor-linked proteolysis of membrane-bound glucagon yields a membrane-associated hormone fragment.

We have studied, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography, glucagon-receptor complexes that arise from the incubation of canine hepatic plasma membranes with [[125I]iodo-Tyr10]glucagon. While a 54,000-dalton membrane protein was tentatively identified as the glucagon receptor by chemical cross-linking, an additional component having an apparent molecular weight of 30,000 was routinely identified as also resulting from glucagon-receptor interactions. The latter material, however, was not observed when gels were fixed prior to autoradiography and was not affected by the addition of cross-linking agents to membrane incubations. Subsequent analysis actually identified the material as a fragment of radiolabeled glucagon that contains at least residues 1-13, has no ability of its own to associate with plasma membranes, and remains tightly membrane bound once it has been formed by receptor-mediated processes. Formation of the fragment was inhibited by phenylmethylsulfonyl fluoride, glucagon, and GTP, but not by N-ethylmaleimide or by a variety of glucagon-related peptides. Overall, our results identify a proteolytic modification of glucagon this is linked to the binding of ligand to high affinity GTP-dependent receptors and the existence of a physically distinct state of receptor in which the binding site is tightly filled by a ligand fragment.

Characterization of a glucagon receptor-linked protease from canine hepatic plasma membranes. Partial purification, kinetic analysis, and determination of sites for hormone processing.

Previous studies have identified the association of the hepatic glucagon receptor with a membrane-bound protease which cleaves [[125I]iodo-Tyr10]glucagon in a hormone- and GTP-sensitive manner (Sheetz, M. J., and Tager, H. S. (1988) J. Biol. Chem. 263, 8509-8514). The current investigations were undertaken to characterize the receptor-linked protease. Treatment of canine hepatic membranes with buffers containing Lubrol and NaCl, followed by gel filtration of soluble material on Sepharose CL-6B and subsequent fractionation of proteins by use of (NH4)2SO4, resulted in a 50-fold purification of the enzyme. Kinetic analysis of the solubilized protease under conditions of linear initial rate (by use of glucagon as substrate and high performance liquid chromatography to separate and quantitate the products) revealed its minimal dependency on pH between values of 7 and 9, its relative preference for glucagon as substrate, and its sensitivity to the presence of salt. Initial rates and the ratio Vmax/Km typically increased 5- to 7-fold and 10-fold, respectively, in the presence of 1 M NaCl. Identification by amino acid analysis of peptide fragments resulting from the incubation of glucagon with the partially purified enzyme and analysis of related time courses for hormone processing demonstrated that the glucagon Tyr13-Leu14 peptide bond is the primary site for proteolytic cleavage by the receptor-linked protease. The implications of these and related findings are discussed.