Ichiro Koni

Increased Plasma Levels of Immunoreactive Endothelin and von Willebrand Factor In NIDDM Patients

OBJECTIVES To elucidate the significance of plasma levels of endothelin (ET) and von Willebrand factor (vWF) as possible markers for endothelial dysfunction in non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS Plasma levels of ET and vWE were determined in 22 NIDDM patients with or without retinopathy and 10 normal control subjects. RESULTS The plasma levels of immunoreactive endothelin (irET) and vWF in NIDDM patients were 0.78 ± 0.06 pmol/1 and 218.3 ± 18.4%, respectively, which represented significant (P < 0.05, P < 0.01, respectively) differences from the values in the control group (0.50 ± 0.06 pmol/1 and 139.1 ± 11.1%, respectively, n = 10). However, when the diabetic patients were divided into two groups according to the presence or absence of diabetic retinopathy, the plasma levels of irET and vWF in the NIDDM patients with retinopathy were significantly higher (1.01 ± 0.07 pmol/1 and 283.0 ± 21.4%, respectively, n = 12) compared with the control group and NIDDM patients without retinopathy (0.59 ± 0.06 pmol/1 and 164.3 ± 17.0%, respectively). Plasma levels of irET showed a significant (P < 0.01) positive correlation with the levels of vWF. CONCLUSIONS These data strongly suggest that increased plasma irET reflects the endothelial cell damage in NIDDM.

Correlation between serum carnitine levels and erythrocyte osmotic fragility in hemodialysis patients.

The relationship between serum carnitine levels and erythrocyte osmotic fragility was investigated in 26 chronic hemodialysis patients (10 males and 16 females, mean age: 57.3 +/- 13.5 years). Serum total-carnitine (TC), free-carnitine (FC) and acyl-carnitine (AC) levels were determined by a spectrophotometric method. Erythrocyte osmotic fragility was measured with a coil planet centrifuge. Serum TC levels were 39.9 +/- 13.4 mumol/l (mean +/- SD), FC levels were 21.8 +/- 7.8 mumol/l and AC levels were 18.0 +/- 9.6 mumol/l. The mean hemolysis end point (HEP) was 67.4 +/- 5.4 mOsM, the hemolysis maximum point (HMP) was 86.3 +/- 5.4 mOsM and the hemolysis start point (HSP) was 101.2 +/- 4.4 mOsM. Each hemolysis point in hemodialysis patients was elevated in comparison with the normal range. There were no significant differences in hemolysis points between a recombinant human erythropoietin (rhEPO)-treated group and nontreated group. HEP correlated with serum TC (r = -0.56, p < 0.01) and AC levels (r = -0.58, p < 0.01). HMP correlated with serum TC (r = -0.42, p < 0.05) and FC levels (r = -0.41, p < 0.05). Dose requirement of rhEPO maintaining target hematocrit correlated with serum TC (r = 0.54, p < 0.05) and FC levels (r = 0.50, p < 0.05). These data support that low serum carnitine levels accelerate erythrocyte osmotic fragility. Carnitine may contribute to the metabolism of erythrocyte membrane and have an impact on the efficacy of rhEPO in correcting renal anemia.

Angiotensin-converting enzyme inhibitors are associated with the need for increased recombinant human erythropoietin maintenance doses in hemodialysis patients.

The influence of angiotensin-converting enzyme inhibitors (ACEIs) on recombinant human erythropoietin (rhEPO) maintenance doses in hemodialysis patients was studied. One hundred and eight chronic hemodialysis patients (55 males and 53 females, mean age 61.2 ± 12.6 years) were investigated. The rhEPO maintenance doses in the ACEI-treated group (n = 49) were 101.7 ± 51.7 U/kg/week and in the nontreated group (n = 59) 79.2 ± 37.8 U/kg/week (p < 0.05). No difference was observed in hematocrit between the ACEI-treated and nontreated groups. In stepwise regression analysis, the parameters associated with increased rhEPO maintenance doses were female gender, ACEI administration, low total iron binding capacity, and low serum free carnitine levels. In conclusion, ACEI administration might reduce the response to rhEPO. In hemodialysis patients who need high-dose rhEPO to maintain the target hematocrit in the absence of iron deficiency, hyperparathyroidism, infection, malignancy, malnutrition, and aluminum toxicity, ACEI administration should be considered.

Elevated serum levels of soluble membrane cofactor protein (CD46, MCP) in patients with systemic lupus erythematosus (SLE)

Membrane cofactor protein (MCP, CD46) is a cell surface complement regulatory protein which acts as a cofactor for the factor I‐mediated cleavage of the activated complement components C3b/C4b. To evaluate the clinical usefulness of serum soluble CD46 as a marker of disease activity in patients with SLE, serum levels of sCD46 were measured by ELISA, using two MoAbs (M160 and M177), each of which recognized two different epitopes on CD46 molecule in SLE, other autoimmune diseases and healthy controls. Serum sCD46 levels in active SLE patients (30.5 ± 14.1 ng/ml) were significantly higher than those of inactive SLE (5.8 ± 7.1 ng/ml; P = 0.0003), rheumatoid arthritis (14.9 ± 11.6 ng/ml; P = 0.0218), primary Sjögrens syndrome (12.3 ± 11.6 ng/ml; P = 0.0039) and normal controls (7.3 ± 3.6 ng/ml; P = 0.0005). The elevated serum sCD46 levels in active SLE patients significantly decreased from 30.5 ± 14.1 ng/ml to 8.0 ± 6.3 ng/ml after effective corticosteroid and immunosuppressant therapy (P = 0.018). Additionally, we found a significant negative association between increasing concentration of sCD46 and decreasing levels of CH50 in SLE (r = –0.598, P = 0.0009). These results suggest that sCD46 reflects in vivo activation of complement system and provides an additional useful serum parameter of active SLE.

Severe gastrointestinal complications of dialysis-related amyloidosis in two patients on long-term hemodialysis

Two patients undergoing long-term hemodialysis developed severe gastrointestinal complications due to dialysis-related amyloidosis (DRA). Case 1, a 68-year-old male on hemodialysis for 18 years developed marked gastric dilatation and severe paralytic ileus. Five years later he died of peritonitis. Autopsy showed extensive amyloid deposits in the muscle layers and blood vessels throughout the gastrointestinal tract. Case 2, a 56-year-old male on hemodialysis for 19 years, developed panperitonitis due to perforation of the sigmoid colon. The resected colon showed massive amyloid deposits in the muscle layers. In both cases, immunological studies revealed positive staining for antihuman beta2-microglobulin antibody. In long-term hemodialysis patients with gastrointestinal symptoms, gastrointestinal complications of DRA should be considered.

A Pathogenic C Terminus-truncated Polycystin-2 Mutant Enhances Receptor-activated Ca2+ Entry via Association with TRPC3 and TRPC7

Mutations in PKD2 gene result in autosomal dominant polycystic kidney disease (ADPKD). PKD2 encodes polycystin-2 (TRPP2), which is a homologue of transient receptor potential (TRP) cation channel proteins. Here we identify a novel PKD2 mutation that generates a C-terminal tail-truncated TRPP2 mutant 697fsX with a frameshift resulting in an aberrant 17-amino acid addition after glutamic acid residue 697 from a family showing mild ADPKD symptoms. When recombinantly expressed in HEK293 cells, wild-type (WT) TRPP2 localized at the endoplasmic reticulum (ER) membrane significantly enhanced Ca2+ release from the ER upon muscarinic acetylcholine receptor (mAChR) stimulation. In contrast, 697fsX, which showed a predominant plasma membrane localization characteristic of TRPP2 mutants with C terminus deletion, prominently increased mAChR-activated Ca2+ influx in cells expressing TRPC3 or TRPC7. Coimmunoprecipitation, pulldown assay, and cross-linking experiments revealed a physical association between 697fsX and TRPC3 or TRPC7. 697fsX but not WT TRPP2 elicited a depolarizing shift of reversal potentials and an enhancement of single-channel conductance indicative of altered ion-permeating pore properties of mAChR-activated currents. Importantly, in kidney epithelial LLC-PK1 cells the recombinant 679fsX construct was codistributed with native TRPC3 proteins at the apical membrane area, but the WT construct was distributed in the basolateral membrane and adjacent intracellular areas. Our results suggest that heteromeric cation channels comprised of the TRPP2 mutant and the TRPC3 or TRPC7 protein induce enhanced receptor-activated Ca2+ influx that may lead to dysregulated cell growth in ADPKD.

Effect of L-Carnitine and Palmitoyl-L-Carnitine on Erythroid Colony Formation in Fetal Mouse Liver Cell Culture

The administration of L-carnitine to patients undergoing hemodialysis increases hematocrit and improves the response to recombinant human erythropoietin (rhEPO). This suggests a contribution by carnitine to erythrocyte membrane function or erythropoiesis. We investigated the effect of L-carnitine and palmitoyl-L-carnitine on erythropoiesis by assessing erythroid colony formation in in vitro fetal mouse liver cell cultures. L-Carnitine or palmitoyl-L-carnitine was added with rhEPO to fetal mouse liver cell cultures. Doses of L-carnitine of up to 200 µmol/l to the culture had no effect on colony formation. In contrast, the addition of above 12.5 µmol/l palmitoyl-L-carnitine into the culture increased colony formation significantly. These results suggest that long-chain acyl carnitine may have an effect on erythropoiesis.

Absence of CD69 expression on peripheral eosinophils in episodic angioedema and eosinophilia.

A 45‐year‐old woman with episodic angioedema and eosinophilia is presented. CD69, which is one of the surface antigens of activated eosinophils, was not expressed on the peripheral eosinophils in this patient, in contrast to hypereosinophilic syndrome. This suggests that CD69, which is not dependent on eosinophil density, may be another useful activation marker of eosinophils to distinguish episodic angioedema and eosinophilia from hypereosinophilic syndrome.

Treatment of Congenital Nephrogenic Diabetes insipidus with Hydrochlorothiazide and Amiloride in an Adult Patient

Aim: The effects of treatment with hydrochlorothiazide (HCTZ) combined with amiloride were elucidated and compared to HCTZ treatment alone and combined with acemetacin or triamterene in a Japanese adult patient with congenital nephrogenic diabetes insipidus. Methods: The study was divided into seven periods: (1) HCTZ and acemetacin; (2) control period; (3) HCTZ; (4) a second control period; (5) HCTZ and amiloride; (6) a third control period, and (7) HCTZ and triamterene. Fluid intake, urine volume, urinary Na, K, creatinine, and osmolality and serum Na, K, Cl, CO2, and osmolality were measured, and free water clearance and proximal and distal tubular Na reabsorption rates were calculated. Results: Without drug administration, the urine volume was about 8,000 ml/day. The urine volume was reduced to about 6,000 ml/day with HCTZ. A further urine volume reduction to about 5,000 ml/day was obtained with the second drug administration, and the effects were similar among the three regimens. Serum and urinary osmolality and free water clearance were also similar among the three combinations, whereas the urinary potassium excretion was the least, and the serum potassium concentration was the highest with HCTZ plus amiloride. Besides, no alkalosis was observed only with this combination. Conclusion: HCTZ plus amiloride may be superior to HCTZ plus acemetacin and HCTZ plus triamterene in preventing hyperkaliuria, hypokalemia, and metabolic alkalosis.

LDL apheresis followed by corticosteroid therapy as a possible treatment of cholesterol crystal embolism

Abstract A 66-year-old man with an abdominal aneurysm who developed renal failure and had blue toes after coronary angiography was transferred to our hospital, and cholesterol crystal embolism was diagnosed by renal and skin biopsies. After the initiation of low-density lipoprotein apheresis (LDL-A) following short-term corticosteroid therapy, in pain and the blueness in the toes disappeared rapidly, and inflammation decreased, but after the discontinuance of these therapies renal function and inflammation worsened again. Following the re-administration of corticosteroid, the inflammation disappeared and renal function gradually recovered. Although LDL-A is an effective treatment for the control of pain due to blue toes, its effect is additive. However, corticosteroid is a possible treatment for cholesterol crystal embolism, particularly in patients with severe inflammatory reaction, which suggests the possible participation of inflammatory or immunological factors in the progression of cholesterol crystal embolism.