The Diabetes Telemonitoring Study Extension: an exploratory randomized comparison of alternative interventions to maintain glycemic control after withdrawal of diabetes home telemonitoring.

Background: Telemonitoring interventions featuring transmission of home glucose records to healthcare providers have resulted in improved glycemic control in patients with diabetes. No research has addressed the intensity or duration of telemonitoring required to sustain such improvements.

Purpose: The DiaTel study (10 January 2005 to 1 November 2007) compared active care management (ACM) with home telemonitoring (n=73) to monthly care coordination (CC) telephone calls (n=77) among veterans with diabetes and suboptimal glycemic control.

Active care management supported by home telemonitoring in veterans with type 2 diabetes: the DiaTel randomized controlled trial.

OBJECTIVE We compared the short-term efficacy of home telemonitoring coupled with active medication management by a nurse practitioner with a monthly care coordination telephone call on glycemic control in veterans with type 2 diabetes and entry A1C > or =7.5%. RESEARCH DESIGN AND METHODS Veterans who received primary care at the VA Pittsburgh Healthcare System from June 2004 to December 2005, who were taking oral hypoglycemic agents and/or insulin for > or =1 year, and who had A1C > or =7.

Acceleration of diabetic renal injury in the superoxide dismutase knockout mouse: effects of tempol.

Indices of renal injury and oxidative stress were examined in mice with deficiency of cytosolic Cu(2+)/Zn(2+) superoxide dismutase (SOD1-/-, KO) and their wild-type (WT) littermates with streptozotocin-induced diabetes. After 5 weeks of diabetes, KO diabetic (D) but not WT-D mice developed marked albuminuria, increases in glomerular content of transforming growth factor beta, collagen alpha1(IV), and nitrotyrosine, and higher glomerular superoxide compared with corresponding values in nondiabetics. After 5 months of diabetes, increases in these parameters, mesangial matrix expansion, renal cortical malondialdehyde content, and severity of tubulointerstitial injury were all significantly greater, whereas cortical glutathione was lower, in KO-D than in WT-D.

Attenuation of renal injury in db/db mice overexpressing superoxide dismutase: evidence for reduced superoxide-nitric oxide interaction.

The effects of overexpression of Cu(2+)/Zn(2+) superoxide dismutase-1 (SOD-1) on indexes of renal injury were compared in 5-month-old nontransgenic (NTg) db/db mice and db/db mice hemizygous for the human SOD-1 transgene (SOD-Tg). Both diabetic groups exhibited similar hyperglycemia and weight gain. However, in NTg-db/db mice, albuminuria, glomerular accumulation of immunoreactive transforming growth factor-beta, collagen alpha1(IV), nitrotyrosine, and mesangial matrix were all significantly increased compared with either nondiabetic mice or SOD-Tg-db/db.

Monoclonal gammopathy and spurious hypophosphatemia.

Background: Spuriously low levels of plasma phosphate have been reported previously in patients with multiple myeloma and polyclonal gammopathy. We report 2 cases of spurious hypophosphatemia in patients with elevated concentrations of serum monoclonal immunoglobulins, 1 of whom had monoclonal gammopathy of undetermined significance and the other multiple myeloma.

Methods: Plasma phosphate concentrations were measured using nondeproteinized and deproteinized plasma samples from patients with monoclonal gammopathies.

Alpha-lipoic acid attenuates hyperglycemia and prevents glomerular mesangial matrix expansion in diabetes.

Previous studies demonstrated that 2 mo of dietary supplementation with alpha-lipoic acid (LA) prevented early glomerular injury in non-insulin-treated streptozotocin diabetic rats (D). The present study examined the effects of chronic LA supplementation (30 mg/kg body wt per d) on nephropathy in D after 7 mo of diabetes. Compared with control rats, D developed increased urinary excretion of albumin and transforming growth factor beta, renal insufficiency, glomerular mesangial matrix expansion, and glomerulosclerosis in association with depletion of glutathione and accumulation of malondialdehyde in renal cortex.

Overexpression of manganese superoxide dismutase suppresses increases in collagen accumulation induced by culture of mesangial cells in high-media glucose.

Superoxide has been implicated in the cellular signalling pathways, which regulate growth of mesangial cells (MC) and vascular smooth muscle cells. Manganese (Mn)(2+)-dependent superoxide dismutase (SOD-2) is primarily responsible for metabolism of superoxide produced in mitochondria by respiratory chain activity during aerobic metabolism of glucose and other substrates. In the current studies, we examined the role of superoxide in the stimulation of collagen accumulation induced in MC by culture in media containing a high concentration of glucose.

Overexpression of Cu2+/Zn2+ superoxide dismutase protects against early diabetic glomerular injury in transgenic mice.

Ex vivo and in vitro observations implicate superoxide as a mediator of cell injury in diabetes, but in vivo evidence is lacking. In the current studies, parameters of glomerular injury were examined in hemizygous nondiabetic transgenic mice (SOD) and streptozotocin-diabetic (D) transgenic mice (D-SOD), which overexpress human cytoplasmic Cu2+/Zn2+ superoxide dismutase (SOD-1), and in corresponding wild-type littermates (WT, D-WT) after 4 months of diabetes. In both SOD and D-SOD mice, renal cortical SOD-1 activity was twofold higher than values in the WT mice; blood glucose and glycosylated hemoglobin (GHb) levels did not differ in the two diabetic groups.

Effects of dietary supplementation of alpha-lipoic acid on early glomerular injury in diabetes mellitus.

Antioxidants, in particular vitamin E (VE), have been reported to protect against diabetic renal injury. alpha-Lipoic acid (LA) has been found to attenuate diabetic peripheral neuropathy, but its effects on nephropathy have not been examined. In the present study, parameters of glomerular injury were examined in streptozotocin diabetic rats after 2 mo on unsupplemented diets and in diabetic rats that received the lowest daily dose of dietary LA (30 mg/kg body wt), VE (100 IU/kg body wt), or vitamin C (VC; 1 g/kg body wt), which detectably increased the renal cortical content of each antioxidant.

Regulation of the laminin C1 promoter in cultured mesangial cells.

Expression of the genes encoding several matrix proteins, including the laminin gamma1 and beta1 subunits, is increased in glomeruli or renal cortex from diabetic animals or in mesangial cells cultured in high concentrations of glucose. Transforming growth factor (TGF)-beta1 and IGF-1 have been implicated as mediators of this response. In the present study, we assessed the influence of high glucose concentrations and the roles of TGF-beta1 and IGF-1 in the regulation of laminin C1 gene expression in cultured mesangial cells.

Effects of supplementation with vitamin C or E on albuminuria, glomerular TGF-beta, and glomerular size in diabetes.

Oxidant stress and a reduction in antioxidant status, including reduced plasma and tissue ascorbic acid content, occur in diabetic patients and experimental models of diabetes. In this study, the effects of treatment of streptozotocin diabetic rats for 2 mo with vitamin C (10 g/kg body wt/d) or dietary vitamin E (200 mg/kg body wt/d) in the drinking water on urinary albumin excretion, glomerular transforming growth factor (TGF)-beta content, and glomerular size were examined. Treatment of diabetic rats with vitamin C or E had no effect on blood glucose levels compared with that in untreated diabetics (453 +/- 28 g/dl +/- SEM).

Antioxidant inhibition of protein kinase C-signaled increases in transforming growth factor-beta in mesangial cells.

Protein kinase C (PKC)-signaled increases in transforming growth factor beta (TGF beta) have been implicated in the stimulation of matrix protein synthesis induced by high concentrations of glucose, thromboxane, angiotension II (AII), and other stimuli in cultured glomerular mesangial cells. In the present study, the effects of several antioxidants on mesangial cell responses to high glucose, thromboxane, and AII were examined. alpha-Tocopherol blocked increases in PKC, TGF beta bioactivity, collagen, and/or fibronectin synthesis induced in mesangial cells by high glucose, the thromboxane analog U46619, and AII.

Nitric oxide inhibition of transforming growth factor-beta and collagen synthesis in mesangial cells.

Culture of mesangial cells (MCs) in 5.6 vs. 30.

Thromboxane/prostaglandin endoperoxide-induced hypertrophy of rat vascular smooth muscle cells is signaled by protein kinase C-dependent increases in transforming growth factor-beta.

In the present study, we examined the effect of the thromboxane/prostaglandin endoperoxide analogue U46619 on proliferation and hypertrophy in cultured rat vascular smooth muscle cells and the roles of protein kinase C and transforming growth factor-beta (TGF-beta) in the mediation of the hypertrophic response to U46619. Since an increase in basic fibroblast growth factor (bFGF) was previously shown to mediate the hypertrophic response to U46619, we also assessed the relationship between bFGF and TGF-beta in the expression of U46619 actions. U46619 increased [35S]methionine incorporation into protein and protein content of vascular smooth muscle cells but had no effect on cell number.

Nitric oxide suppresses increases in mesangial cell protein kinase C, transforming growth factor beta, and fibronectin synthesis induced by thromboxane.

Thromboxane (TX) stimulation of fibronectin (FN) synthesis in mesangial cells (MC) is dependent on protein kinase C (PKC)-mediated increases in transforming growth factor beta (TGF beta), and is suppressed by increases in cellular cGMP. The current studies evaluate the role of cGMP-dependent and -independent actions of nitric oxide (NO) in modulating the responses of MC to the TX analogue U46619. TX-stimulated increases in PKC activity, TGF beta, and FN synthesis in MC were suppressed by either 8-Br-PET-cGMP or the NO donor S-nitroso-N-acetylpenicillamine (SNAP).

Protein kinase C in diabetic nephropathy.

Protein kinase C is activated in numerous tissues obtained from diabetic animals and in several cultured cell systems exposed to high media glucose in vitro including glomerular mesangial cells. Several activators of protein kinase C, such as high media glucose, angiotensin II, phorbol ester, low density lipoprotein, and the thromboxane analogue U-46619, increase TGF beta bioactivity or mRNA expression and increase the synthesis of extracellular matrix proteins by mesangial cells in culture. The studies described in the present report support the hypothesis that activation of protein kinase C by thromboxane, an eicosanoid whose production is known to be elevated in diabetes, increases TGF beta production by mesangial cells in culture.

Protein kinase C signals thromboxane induced increases in fibronectin synthesis and TGF-beta bioactivity in mesangial cells.

Previous studies have demonstrated that thromboxane (TX) stimulates matrix protein synthesis in mesangial cells (MC), and that this action is signalled by receptor mediated activation of protein kinase C (PKC). In the present study, we examined the hypothesis that activation of PKC by TX signals increases in transforming growth factor beta (TGF-beta) bioactivity, which in turn induces enhanced matrix protein synthesis. In cultured rat MC, the TXA2/prostaglandin endoperoxide analogue U-46619, but not exogenous human platelet TGF-beta 1, activated PKC as reflected by enhanced in situ phosphorylation of MARCKS protein, an endogenous substrate of PKC.

Impaired nitric oxide release by glomeruli from diabetic rats.

Basal nitric oxide (NO) production and NO responses to carbamylcholine (CCh) and the Ca2+ ionophore A23187 were measured with a NO electrode in glomeruli isolated from 2 to 3-month-diabetic versus age-matched control rats. In the presence of CCh or A23187, NO production was markedly reduced in glomeruli from diabetic versus control rats. Spontaneous generation of NO by s-nitrosopenicillamine (SNAP) was also reduced in the presence of glomeruli from diabetic rats as compared with values either in control glomeruli or in buffer alone.

Role for transforming growth factor beta in thromboxane-induced increases in mesangial cell fibronectin synthesis.

Thromboxane A2 (TXA2) has been implicated in the pathogenesis of progressive glomerulosclerosis and stimulates the synthesis of matrix protein by mesangial cells (MCs). This study examined the role of transforming growth factor beta (TGF-beta) in the mediation of the action of the stable TXA2/prostaglandin (PG) endoperoxide analog U-46619 to stimulate fibronectin (Fn) synthesis in cultured rat MC. Exogenous TGF-beta increased Fn synthesis by MC in a concentration- and time-dependent fashion, as reflected by incorporation of [35S]methionine into immunoprecipitable Fn.

Low-density lipoprotein stimulation of mesangial cell fibronectin synthesis: role of protein kinase C and transforming growth factor-beta.

Low-density lipoprotein (LDL) cholesterol has been implicated in the pathogenesis of glomerulosclerosis in diabetes and other forms of glomerular injury. In the present study we evaluated the effect of LDL on fibronectin synthesis in cultured rat mesangial cells (MCs) and the roles of protein kinase C (PKC) and transforming growth factor-beta (TGF-beta) in mediating this LDL action. In MCs, 25 micrograms to 100 micrograms/ml LDL increased PKC activity within 15 minutes, as reflected by enhanced in situ phosphorylation of the 80 kd myristoylated alanine-rich C kinase substrate protein, a specific endogenous substrate of PKC in MC.

Thromboxane stimulation of mesangial cell fibronectin synthesis is signalled by protein kinase C and modulated by cGMP.

Thromboxane (TX) has been implicated in the pathogenesis of glomerulosclerosis in several models of glomerular injury. In the present study, we examined the role of the protein kinase C (PKC) signalling system in expression of the action of the TXA2/PGH2 analogue U-46619 to stimulate fibronectin (Fn) synthesis in cultured rat mesangial cells (MC), and the influence of cGMP on this MC response. U-46619 activated PKC and enhanced Fn synthesis in MC in a time and concentration dependent fashion.

Loss of protein kinase C delta isozyme immunoreactivity in human adenocarcinomas.

Protein kinase C (PKC) has been implicated in the control of colonic epithelial proliferative activity and in the process of malignant transformation. In the present study, we assessed by histone IIIS phosphorylation in vitro, total PKC activity, and the subcellular distribution of this activity in human adenocarcinomas and surrounding uninvolved mucosa from six patients. In these same tissues, we also examined the isozyme profile of PKC by immunoblotting.

Activation of protein kinase C in glomerular cells in diabetes. Mechanisms and potential links to the pathogenesis of diabetic glomerulopathy.

Protein kinase C (PKC) is activated in rat renal glomerulus within a week of induction of experimental diabetes. Studies in isolated glomeruli and in cultured endothelial and mesangial cells have demonstrated that high ambient concentrations of glucose activate PKC and thus implicate hyperglycemia per se as a mediator of PKC activation in glomerular cells in diabetes. High glucose concentrations activate PKC by increasing cellular levels of diacylglycerol (DAG), the major endogenous modulator of this signalling system.