IgM-mediated Warm Autoimmune Hemolytic Anemia: An Autopsy Report.

A 79-year-old man with Sjögren's syndrome and systemic lupus erythematosus developed acute impaired consciousness and hemolytic anemia. The patient's red blood cells agglutinated spontaneously at 25-37°C. The treatment of red blood cells with 2-mercaptoethanol resulted in the loss of spontaneous agglutination. A diagnosis of IgM-mediated warm autoimmune hemolytic anemia was made. The patient received steroid pulse and plasma exchange therapies. Rituximab was also administered. However, the patient died from multiple organ failure at six days from the symptom onset. The clinical progress of the patient and autopsy findings suggested that complement activation might have been associated with the pathology.

Electrical determination of current injection and internal quantum efficiencies in AlGaN-based deep-ultraviolet light-emitting diodes.

We propose a method to determine the current injection efficiency (CIE) and internal quantum efficiency (IQE) of light-emitting diodes (LEDs) during current injection. The method is based on fourth-order polynomial fitting of a modified rate equation to electroluminescence data. Our method can extract the CIE at low injection current densities, unlike conventional methods that generally assume the CIE to be unity. We apply the method to AlGaN-based deep-ultraviolet LEDs. Results show that the CIE was only approximately 51% at low injection current densities and was almost independent of injection current density up to 100 A/cm2. The peak IQE was 77%.

Comparative Effects of Direct Renin Inhibitor and Angiotensin Receptor Blocker on Albuminuria in Hypertensive Patients with Type 2 Diabetes. A Randomized Controlled Trial.

BACKGROUND: In patients with diabetes, albuminuria is a risk marker of end-stage renal disease and cardiovascular events. An increased renin-angiotensin system activity has been reported to play an important role in the pathological processes in these conditions. We compared the effect of aliskiren, a direct renin inhibitor (DRI), with that of angiotensin receptor blockers (ARBs) on albuminuria and urinary excretion of angiotensinogen, a marker of intrarenal renin-angiotensin system activity. METHODS: We randomly assigned 237 type 2 diabetic patients with high-normal albuminuria (10 to <30 mg/g of albumin-to-creatinine ratio) or microalbuminuria (30 to <300 mg/g) to the DRI group or ARB group (any ARB) with a target blood pressure of <130/80 mmHg. The primary endpoint was a reduction in albuminuria. RESULTS: Twelve patients dropped out during the observation period, and a total of 225 patients were analyzed. During the study period, the systolic and diastolic blood pressures were not different between the groups. The changes in the urinary albumin-to-creatinine ratio from baseline to the end of the treatment period in the DRI and ARB groups were similar (-5.5% and -6.7%, respectively). In contrast, a significant reduction in the urinary excretion of angiotensinogen was observed in the ARB group but not in the DRI group. In the subgroup analysis, a significant reduction in the albuminuria was observed in the ARB group but not in the DRI group among high-normal albuminuria patients. CONCLUSION: DRI and ARB reduced albuminuria in hypertensive patients with type 2 diabetes. In addition, ARB, but not DRI, reduced albuminuria even in patients with normal albuminuria. DRI is not superior to ARB in the reduction of urinary excretion of albumin and angiotensinogen.

Granulomatosis with polyangiitis presenting as an orbital inflammatory pseudotumor: a case report.

INTRODUCTION: Granulomatosis with polyangiitis is a systemic inflammatory disease that often presents with necrosis, granuloma formation and vasculitis of small- to medium-sized vessels. Affected patients usually present with disease of the upper respiratory tract, lungs and kidneys, but this disease has been reported to involve almost any organ. We report the case of a patient with ocular manifestations of granulomatosis with polyangiitis after the remission of renal and auditory manifestations. CASE PRESENTATION: An 81-year-old Japanese woman had a four-year history of biopsy-proven antineutrophil cytoplasmic antibody-related glomerulonephritis that had been treated with oral prednisolone and was in serological remission. She had also recovered from a one-year history of complete hearing loss immediately following the steroid treatment for glomerulonephritis. She gradually experienced right eye visual disturbance and exophthalmos over a two-month period. Radiographic and histopathological findings revealed an orbital inflammatory pseudotumor. The administration of prednisolone completely restored her right eye visual acuity and eye movement after two weeks. Considering this case retrospectively, our patient had an orbital inflammatory pseudotumor caused by granulomatosis with polyangiitis including a medical history of reversible hearing loss, although her glomerulonephritis had remitted with an undetectable level of specific antineutrophil cytoplasmic antibody. CONCLUSIONS: In this patient, hearing loss and visual loss occurred at different times during the course of treatment of granulomatosis with polyangiitis. Clinicians should consider a differential diagnosis of granulomatosis with polyangiitis in patients with treatable hearing and visual loss.

Carnitine deficiency presenting with a decreased mental state in a patient with amyotrophic lateral sclerosis receiving long-term tube feeding: a case report.

INTRODUCTION: L-carnitine is an important metabolic mediator involved in fatty acid transport. It is obtained from the diet, particularly from animal products, such as red meat. Previous reports have revealed that long-term tube feeding with a commercial product containing no or low levels of carnitine can lead to an altered mental state caused by hyperammonemia. CASE PRESENTATION: A 72-year-old Japanese man had a 12-year history of amyotrophic lateral sclerosis. He was bedridden and had required mechanical ventilation and enteral tube feeding for 10 years at home. His main enteral solution was a commercial product that contained low carnitine levels, and he sometimes received coffee and homemade products such as miso soup. Our patient's ability to communicate gradually deteriorated over a period of one year. His serum total carnitine level was abnormally low, at 26.7µmol/L (normal range, 45 to 91µmol/L), but his ammonium level was normal. His mental state improved dramatically after starting L-carnitine supplementation (600mg twice daily). CONCLUSION: This case highlights the importance of avoiding carnitine deficiency in patients with amyotrophic lateral sclerosis undergoing long-term tube feeding. These patients experience progressive muscle atrophy that might cause impaired carnitine storage and might manifest as communication difficulties. Carnitine deficiency can be misdiagnosed as a progression of systemic muscle atrophy. Clinicians should be aware of this disorder and should consider periodically measuring carnitine levels, regardless of the patient's serum ammonium levels.

Postprandial activation of protein kinase Cµ regulates the expression of adipocytokines via the transcription factor AP-2ß.

Abnormal secretion of adipocytokines promotes atherosclerosis, diabetes and insulin resistance, and is mainly induced by adipocyte hypertrophy. Recently, the circulating adipocytokine concentrations were reported to change in the postprandial period, as the levels of TNFα, IL-6 IL-8 and MCP-1 increased after a meal, whereas that of adiponectin decreased. These data suggest that prandial modulation of cytokines may be involved in the pathogenesis of atherosclerosis in type 2 diabetes. However, the regulatory mechanism of such change is still unclear. In the present study, we identified this mechanism with a special focus on the functions of protein kinase C (PKC) and of the transcription factor AP-2ß, both of which are associated with the pathophysiology of adipocytokine regulation. PKCµ was highly phosphorylated in the re-feeding condition compared to the fasting condition in mouse adipose tissue, while other PKC isoforms remained unchanged. Furthermore, overexpression of PKCµ in 3T3-L1 adipocytes, but not other PKC isoforms, positively regulated the mRNA expression and promoter activity of MCP-1 and IL-6, and negatively regulated those of adiponectin. AP-2ß had similar effects on the expression and promoter activity of these adipocytokines. Interestingly, overexpression of PKCµ enhanced the stimulatory and inhibitory effects of AP-2ß on the expression of these adipocytokines. Finally, PKCµ could not activate a mutant MCP-1 promoter lacking the AP-2ß binding domain. Our results suggest that postprandial activation of PKCµ plays a role in disordered postprandial adipocytokine expression through AP-2ß.

Association between serum soluble TNFα receptors and renal dysfunction in type 2 diabetic patients without proteinuria.

AIM: The aim of our study was to investigate whether serum levels of soluble tumor necrosis factor α receptor (sTNFR) 1 and 2 are markers for renal dysfunction in type 2 diabetic patients without overt proteinuria. METHODS: Japanese type 2 diabetic patients without overt proteinuria (n = 168) enrolled in the prospective observational follow-up study in 2001 were retrospectively analyzed. At baseline, the serum levels of sTNFR1 and sTNFR2 were measured by sandwich ELISA. The associations between these markers and change in estimated glomerular filtration rate (eGFR) after 5 years were evaluated. RESULTS: The levels of sTNFR1 and sTNFR2 closely correlated. At baseline, sTNFR1 and sTNFR2 associated inversely with eGFR. After 5 years, patients with high level of both sTNFR1 and sTNFR2 showed a greater decline in eGFR (-13.8 ± 15.5% versus -8.5 ± 11.8%, P = 0.027) and a 4-fold higher risk for a GFR decline of ≥ 25% than those with high level of only one receptor or low level of both receptors. These associations were enhanced in diabetic women. CONCLUSIONS: The higher levels of sTNFR1 and sTNFR2 were associated with a greater decline in eGFR in type 2 diabetic patients without proteinuria, especially in diabetic women.

Transcription factor AP-2beta: a negative regulator of IRS-1 gene expression.

Down-regulation of insulin receptor substrate-1 (IRS-1) expression could modify the ability of IRS-1 to fulfill its functions. It has been proposed that the phosphorylation of IRS-1 on serine residues could promote its degradation. However, few studies have investigated the transcriptional regulation of IRS-1 in the pathogenesis of insulin resistance. Genotyping for genome-wide single nucleotide polymorphisms revealed that the transcription factor activating enhancer-binding protein-2beta (AP-2beta) is a novel candidate gene for conferring susceptibility to obesity and type 2 diabetes. AP-2beta is expressed in adipose tissue and its expression is increased during the maturation of adipocytes. Overexpression of AP-2beta leads to adipocyte hypertrophy, directly inhibits adiponectin expression, and enhanced the expression of inflammatory adipokines such as IL-6 and MCP-1. In this study, we found that overexpression of AP-2beta in 3T3-L1 adipocytes impaired the promoter activity of IRS-1, and subsequently decreased mRNA and protein expression. Electrophoretic mobility shift assays showed that AP-2beta bound specifically to the IRS-1 promoter region. Furthermore, site-directed mutagenesis of the AP-2 binding site located at -362 to -351, relative to the transcription start site, markedly decreased AP-2-induced suppression of IRS-1 promoter activity, whereas other putative AP-2 binding sites did not. Our results clearly showed that AP-2beta directly decreased IRS-1 expression by binding to its promoter. Based on these findings, we speculate that the AP-2beta transcriptional factor is a unique regulator of IRS-1 and a candidate gene for insulin resistance.

Relation of the expression of transcriptional factor TFAP2B to that of adipokines in subcutaneous and omental adipose tissues.

To determine the potential role of the transcriptional factor-activating enhancer-binding protein-2beta (TFAP2B) in the regulation of expression of adipokines, adiponectin, leptin, and interleukin-6 (IL-6) in vivo, we quantified the mRNA expression levels of these adipokines and TFAP2B in visceral (omental) and abdominal subcutaneous adipose tissues of 66 individuals with variable degree of adiposity and studied their correlations with BMI and their plasma concentrations. We found that BMI correlated negatively with plasma adiponectin levels and positively with those of leptin. Adiponection mRNA expression in subcutaneous fat correlated negatively with BMI, whereas leptin mRNA levels in the omentum correlated with plasma leptin levels and BMI. In contrast, IL-6 mRNA levels in subcutaneous and omental fat did not correlate with BMI. IL-6 mRNA levels in the omental fat correlated with plasma IL-6 levels. Whereas TFAP2B mRNA expression did not correlate with BMI, it correlated negatively with adiponectin expression in the subcutaneous adipose tissue. Furthermore, TFAP2B mRNA expression correlated negatively with leptin and positively with IL-6 expression in both subcutaneous and omental adipose tissues. These relationships are consistent with our in vitro observations and indicate that TFAP2B seems to regulate the expression of various adipokines in vivo.

A novel ultra-sensitive enzyme immunoassay for soluble human insulin receptor ectodomain and its measurement in urine from healthy subjects and patients with diabetes mellitus.

OBJECTIVE: For the early identification of patients at risk of developing diabetes mellitus, and to prevent the onset of diabetes by performing dietary counseling and exercise guidance, we have developed an ultra-sensitive immune complex transfer enzyme immunoassay (ICT-EIA) to measure soluble human insulin receptor ectodomain (sIRalpha) in urine which is collected non-invasively. DESIGN AND METHODS: We developed ICT-EIA for sIRalpha and measured urinary sIRalpha from 106 healthy volunteers, 35 obese volunteers and 42 patients with diabetes. RESULTS: The detection limit of ICT-EIA (0.04 pg/mL), using a urine sample of as little as 100 microL, was a few hundred-fold higher than that of conventional ELISA. Using ICT-EIA, the urinary sIRalpha level in patients with diabetes (9.7+/-20.1 pg/mg creatinine) was significantly higher than those in healthy volunteers (1.4+/-0.9; P<0.001). CONCLUSION: ICT-EIA for sIRalpha may be useful as a good marker for evaluating diabetes risk.

SAFB1, an RBMX-binding protein, is a newly identified regulator of hepatic SREBP-1c gene.

Sterol regulatory element-binding protein (SREBP)-1c plays a crucial role in the regulation of lipogenic enzymes in the liver. We previously reported that an X-chromosome-linked RNA binding motif (RBMX) regulates the promoter activity of Srebp-1c. However, still unknown was how it regulates the gene expression. To elucidate this mechanism, we screened the cDNA library from mouse liver by yeast two-hybrid assay using RBMX as bait and identified scaffold attachment factor B1 (SAFB1). Immunoprecipitation assay demonstrated binding of SAFB1 to RBMX. Chromatin immunoprecipitation assay showed binding of both SAFB1 and RBMX to the upstream region of Srebp-1c gene. RNA interference of Safb1 reduced the basal and RBMX-induced Srebp-1c promoter activities, resulting in reduced Srebp-1c gene expression. The effect of SAFB1 overexpression on Srebp-1c promoter was found only in the presence of RBMX. These results indicate a major role for SAFB1 in the activation of Srebp-1c through its interaction with RBMX.

The Rab GTPase-activating protein AS160 as a common regulator of insulin- and Galphaq-mediated intracellular GLUT4 vesicle distribution.

Akt substrate of 160kDa (AS160) is a Rab GTPase activating protein (GAP) and was recently identified as a component of the insulin signaling pathway of glucose transporter type 4 (GLUT4) translocation. We and others, previously reported that the activation of Galphaq protein-coupled receptors (GalphaqPCRs) also stimulated GLUT4 translocation and glucose uptake in several cell lines. Here, we report that the activation of GalphaqPCRs also promoted phosphorylation of AS160 by the 5'-AMP activated protein kinase (AMPK). The suppression of AS160 phosphorylation by the siRNA mediated AMPKalpha1 subunit knockdown promoted GLUT4 vesicle retention in intracellular compartments. This suppression did not affect the ratio of non-induced cell surface GLUT4 to Galphaq-induced it. Rat 3Y1 cells lacking AS160 did not show insulin-induced GLUT4 translocation. The cells stably expressing GLUT4 revealed GLUT4 vesicles that were mainly localized in the perinuclear region and less frequently on the cell surface. After expression of exogenous AS160, GLUT4 on the cell surface decreased and GLUT4 vesicles were redistributed throughout the cytoplasm. Although PMA-induced or sodium fluoride-induced GLUT4 translocation was significantly increased in these cells, insulin did not affect GLUT4 translocation. These results suggest that AS160 is a common regulator of insulin- and GalphaqPCR activation-mediated GLUT4 distribution in the cells.

Transcription factor activating protein-2beta: a positive regulator of monocyte chemoattractant protein-1 gene expression.

We previously reported an association between the activating protein (AP)-2beta transcription factor gene and type 2 diabetes. This gene is preferentially expressed in adipose tissue, and subjects with a disease-susceptible allele of AP-2beta showed stronger AP-2beta expression in adipose tissue than those without the susceptible allele. Furthermore, overexpression of AP-2beta leads to lipid accumulation by enhancing glucose transport and inducing insulin resistance in 3T3-L1 adipocytes. In this study, we found that overexpression of AP-2beta in 3T3-L1 adipocytes accelerated the promoter activity of monocyte chemoattractant protein-1 (MCP-1) and subsequently increased both mRNA and protein expression and protein secretion. Furthermore, knockdown of endogenous AP-2beta by RNA interference reduced the mRNA and the protein expression of MCP-1. EMSAs and chromatin immunoprecipitation assays revealed specific binding of AP-2beta to MCP-1 promoter regions, in vitro and in vivo. Additionally, site-directed mutagenesis of the AP-2 binding site located at -137 to -129 relative to the transcription start site markedly diminished MCP-1 promoter activity, whereas other putative AP-2 binding sites did not. Our results clearly show that AP-2beta directly enhanced MCP-1 secretion by binding to its promoter. Thus, we propose that AP-2beta positively regulates MCP-1 expression; subsequently contributes to the infiltration of macrophages to adipose tissue; and leads to insulin resistance, type 2 diabetes, and cardiovascular diseases.

The E3 ligase TTC3 facilitates ubiquitination and degradation of phosphorylated Akt.

The serine threonine kinase Akt is a core survival factor that underlies a variety of human diseases. Although regulatory phosphorylation and dephosphorylation have been well documented, the other posttranslational mechanisms that modulate Akt activity remain unclear. We show here that tetratricopeptide repeat domain 3 (TTC3) is an E3 ligase that interacts with Akt. TTC3 contains a canonical RING finger motif, a pair of tetratricopeptide motifs, a putative Akt phosphorylation site, and nuclear localization signals, and is encoded by a gene within the Down syndrome (DS) critical region on chromosome 21. TTC3 is an Akt-specific E3 ligase that binds to phosphorylated Akt and facilitates its ubiquitination and degradation within the nucleus. Moreover, DS cells exhibit elevated TTC3 expression, reduced phosphorylated Akt, and accumulation in the G(2)M phase, which can be reversed by TTC3 siRNA or Myr-Akt. Thus, interaction between TTC3 and Akt may contribute to the clinical symptoms of DS.

Deficiency of Cbl-b gene enhances infiltration and activation of macrophages in adipose tissue and causes peripheral insulin resistance in mice.

OBJECTIVE: c-Cbl plays an important role in whole-body fuel homeostasis by regulating insulin action. In the present study, we examined the role of Cbl-b, another member of the Cbl family, in insulin action. RESEARCH DESIGN AND METHODS: C57BL/6 (Cbl-b(+/+)) or Cbl-b-deficient (Cbl-b(-/-)) mice were subjected to insulin and glucose tolerance tests and a hyperinsulinemic-euglycemic clamp test. Infiltration of macrophages into white adipose tissue (WAT) was assessed by immunohistochemistry and flow cytometry. We examined macrophage activation using co-cultures of 3T3-L1 adipocytes and peritoneal macrophages. RESULTS: Elderly Cbl-b(-/-) mice developed glucose intolerance and peripheral insulin resistance; serum insulin concentrations after a glucose challenge were always higher in elderly Cbl-b(-/-) mice than age-matched Cbl-b(+/+) mice. Deficiency of the Cbl-b gene significantly decreased the uptake of 2-deoxyglucose into WAT and glucose infusion rate, whereas fatty liver was apparent in elderly Cbl-b(-/-) mice. Cbl-b deficiency was associated with infiltration of macrophages into the WAT and expression of cytokines, such as tumor necrosis factor-alpha, interleukin-6, and monocyte chemoattractant protein (MCP)-1. Co-culture of Cbl-b(-/-) macrophages with 3T3-L1 adipocytes induced leptin expression and dephosphorylation of insulin receptor substrate 1, leading to impaired glucose uptake in adipocytes. Furthermore, Vav1, a key factor in macrophage activation, was highly phosphorylated in peritoneal Cbl-b(-/-) macrophages compared with Cbl-b(+/+) macrophages. Treatment with a neutralizing anti-MCP-1 antibody improved peripheral insulin resistance and macrophage infiltration into WAT in elderly Cbl-b(-/-) mice. CONCLUSIONS: Cbl-b is a negative regulator of macrophage infiltration and activation, and macrophage activation by Cbl-b deficiency contributes to the peripheral insulin resistance and glucose intolerance via cytokines secreted from macrophages.

AKT1 overexpression in endothelial cells leads to the development of cutaneous vascular malformations in vivo.

BACKGROUND: Vascular malformations are clinical disorders in which endothelial cells fail to remodel and/or undergo programmed cell death, leading to abnormal persistence of blood vessels. The abnormal persistence of vessels makes therapy difficult because these lesions are resistant to interventions that are effective against hemangiomas. Akt1 is a serine-threonine protein kinase, which is a key mediator of resistance to programmed cell death. Our objective was to determine whether sustained activation of Akt1 could lead to vascular malformation in mice. OBSERVATIONS: We examined the effect of constitutive activation of Akt1 in murine endothelial cells (MS1 cells). Overexpression of active AKT1 in MS1 cells led to the development of vascular malformations, characterized by wide endothelial lumens and minimal investment of smooth muscle surrounding the vessels. The histologic features of these vascular malformations is distinct from ras-transformed MS1 cells (angiosarcoma) and suggest that differing signal abnormalities give rise to human vascular malformations vs malignant vascular tumors. CONCLUSIONS: Inhibition of Akt signaling may be useful in the treatment of vascular malformations. Examination of problematic hemangiomas and vascular malformations for the presence of activated Akt or downstream targets of Akt, such as mammalian target of rapamycin (mTOR), may predict response to treatment with Akt inhibitors or rapamycin. This study provides a potential rationale for the systemic and topical use of these inhibitors for vascular malformations and hemangiomas.

Intra-islet insulin suppresses glucagon release via GABA-GABAA receptor system.

Excessive secretion of glucagon is a major contributor to the development of diabetic hyperglycemia. Secretion of glucagon is regulated by various nutrients, with glucose being a primary determinant of the rate of alpha cell glucagon secretion. The intra-islet action of insulin is essential to exert the effect of glucose on the alpha cells since, in the absence of insulin, glucose is not able to suppress glucagon release in vivo. However, the precise mechanism by which insulin suppresses glucagon secretion from alpha cells is unknown. In this study, we show that insulin induces activation of GABAA receptors in the alpha cells by receptor translocation via an Akt kinase-dependent pathway. This leads to membrane hyperpolarization in the alpha cells and, ultimately, suppression of glucagon secretion. We propose that defects in this pathway(s) contribute to diabetic hyperglycemia.

Functional analysis of PIK3CA gene mutations in human colorectal cancer.

Mutations in the PIK3CA gene, which encodes the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3K), have been reported in human cancers, including colorectal cancer. Most of the mutations cluster at hotspots within the helical and kinase domains. Whereas H1047R, one of the hotspot mutants, is reported to have elevated lipid kinase activity, the functional consequences of other mutations have not been examined. In this study, we examined the effects of colon cancer-associated PIK3CA mutations on the lipid kinase activity in vitro, activation of the downstream targets Akt and p70S6K in vivo and NIH 3T3-transforming ability. Of eight mutations examined, all showed increased lipid kinase activity compared with wild-type p110alpha. All the mutants strongly activated Akt and p70S6K compared with wild-type p110alpha as determined by immunoblotting using phospho-specific antibodies. These mutants also induced morphologic changes, loss of contact inhibition, and anchorage-independent growth of NIH 3T3 cells. The hotspot mutations examined in this study, E542K, E545K, and H1047R, all had high enzymatic and transforming activities. These results show that almost all the colon cancer-associated PIK3CA mutations are functionally active so that they are likely to be involved in carcinogenesis.