Ryusuke Murakami

ACE gene polymorphism in childhood IgA nephropathy: Association with clinicopathologic findings

A deletion polymorphism in the angiotensin-converting enzyme (ACE) gene has been reported to be a risk factor for progression to chronic renal failure in immunoglobulin A nephropathy (IgAN). In this study, we investigated the association between ACE gene polymorphism and clinical findings, early biopsy findings such as the extent of mesangial proliferation, focal lesions (capsular adhesions, glomerulosclerosis, and crescents), and the glomerular area in childhood IgAN. Genomic DNA was obtained from 97 patients and control subjects. Gene polymorphisms, consisting of an insertion (I) or deletion (D) of the 287-base pair Alu sequence, were detected using the polymerase chain reaction. The extent of capsular adhesions and glomerulosclerosis was significantly higher in patients with the ID/DD genotypes than in those with the II genotype (ID/DD v II: 8.0%+/-1.4% v 2.5%+/-0.8% [P = 0.017] and 5.1%+/-1.3% v 1.4%+/-0.6% [P = 0.028], respectively). Whereas there was no difference in the extent of mesangial proliferation and crescents between the ID/DD genotypes and the II genotype. Urinary protein excretion at the time of biopsy was significantly greater in patients with the ID/DD genotypes than in those with the II genotype (1.02+/-0.15 g/d/m2 body surface area v 0.56+/-0.13 g/d/m2 body surface area; P = 0.012). These results indicate that ACE gene polymorphism may not influence the extent of mesangial proliferation and crescents that are acute lesions. However, the ID/DD genotypes are associated with chronic lesions, such as capsular adhesions or glomerulosclerosis and urinary protein excretion in childhood IgAN.

Effectiveness of high-dose MCNU therapy and hematopoietic stem cell autografts treatment of childhood acute leukemia/lymphoma with high-risk features.

Clinical and pharmacokinetic studies were performed regarding the toxicity of methyl 6‐[3‐(2‐chloroethyl)‐3‐nitrosoureido]‐6‐deoxy‐α‐D‐glucopyranoside (MCNU) with other drugs, in conjunction with a peripheral blood stem cell autograft (PBSCT), for treating 26 children with acute leukemia or lymphoma associated with high‐risk features. In the early phase of the study, MCNU (300 to 500 mg/m2) was administered with cytosine arabinoside (Ara‐C) (1.6 to 16 g/m2),etoposide (VP‐16) (0.8 to 1.6 g/m2), cyclophosphamide (CY) (100 to 200 mg/kg), or busulfan (16 mg/kg). No acute toxicity was noticed after this high‐dose therapy. The dose‐limiting factor of the regimens was significant but reversible interstitial pneumonitis (IP). In a subsequent trial with an MCNU/VP‐16/Ara‐C/CY (MCVAC) regimen in which the dose of MCNU was reduced, the risk of IP diminished. This study is still in progress, but the clinical response has so far been encouraging. Fifteen of 26 children are alive and well in unmaintained complete remission (CR) with a median follow‐up period of 11 months (range, 3 to 34 months) after transplantation.

Role of platelet-activating factor acetylhydrolase gene mutation in Japanese childhood IgA nephropathy

Platelet-activating factor (PAF) is a potent mediator of inflammatory injury in renal diseases. PAF is degraded to inactive products by PAF acetylhydrolase. Recently, a point mutation (G to T transversion) of the PAF acetylhydrolase gene was observed at position 994, and this mutation was found to contribute to the variability in plasma PAF levels, with undetectable plasma PAF acetylhydrolase activity occurring in homozygous patients (TT genotype) and reduced levels of activity in heterozygous patients (GT genotype). Therefore, we investigated the effect of the PAF acetylhydrolase gene mutation on the pathogenesis and progression of immunoglobulin A (IgA) nephropathy. Genomic DNA was obtained from 89 children with IgA nephropathy and 100 controls. We identified the PAF acetylhydrolase gene mutation (G994T) by polymerase chain reaction. There was no significant difference in genotypic frequency between patients and controls. However, urinary protein excretion at the time of biopsy was significantly greater in patients with the GT/TT genotypes than in those with the GG genotype. The percentage of glomeruli with mesangial cell proliferation was significantly greater in patients with the GT/TT genotypes than in those with the GG genotype. These results indicate the PAF acetylhydrolase gene mutation may influence the degree of proteinuria and the extent of mesangial proliferation in the early stage of childhood IgA nephropathy.

Serum carnitine and nutritional status in children treated with continuous ambulatory peritoneal dialysis.

The serum carnitine (total carnitine), total protein, amino acid, and triglyceride levels were determined in children on continuous ambulatory peritoneal dialysis (CAPD). Compared with levels in controls, serum carnitine levels were significantly decreased in patients on CAPD for more than 4 months, while those of patients on CAPD for 1–3 months were not decreased. Patients on CAPD for more than 4 months also showed lower serum total protein levels than in normal controls. The mean triglyceride levels in patients on CAPD for both 1–3 months and more than 4 months were higher than those in normal controls. Among the amino acids, the serum levels of tryptophan, isoleucine, leucine, tyrosine, valine, serine, and aspargine were significantly lower in patients treated with CAPD than in normal controls, whereas the levels of other amino acids were either increased or not changed. Isoleucine and leucine levels showed a strong correlation with serum carnitine. Our data suggest that malnutrition plays a role in the decrease of serum carnitine levels in patients receiving CAPD.

Sideroblastic anemia showing unique response to pyridoxine.

We treated and followed up for 6 years a patient with pyridoxine-responsive sideroblastic anemia. The patient was a boy age 1 year and 9 months, who was diagnosed on the basis of peripheral red cell morphology and an increased number of sideroblasts in the bone marrow. Bone marrow erythroblasts showed a marked reduction of delta-aminolevulinic acid synthase (ALA-S) activity. The response of the patient to pyridoxine and its active form, pyridoxal phosphate, was unique. After the first course of pyridoxal phosphate therapy (300 to 500 mg/day i.v. for 4 days), all hematological data were restored to normal and remained normal for 29 months without the further administration of pyridoxal phosphate. The second course of pyridoxal phosphate therapy (500 mg/day i.v. for 2 days) was effective for 6 months. The third, fourth, and fifth courses of the therapy consisted of daily oral pyridoxine hydrochloride at a dose of 180 mg/day for 4 to 6 weeks, and the respective periods of hematological remission were 7, 12, and greater than 18 months. These observations suggest the presence of a complicated ALA-S activating or inactivating system, or both, in our patient.

Severe neonatal nemaline myopathy with delayed maturation of muscle

A Japanese infant with a severe neonatal form of nemaline myopathy showed features of muscle immaturity as well as rods in the biopsied quadriceps femoris muscle, and involvement of diaphragm was first confirmed at autopsy. The biopsied muscle showed numerous rods in 80% of muscle fibers, and an increased number of type 2C fibers (23.2%). Electron microscopic findings were characterized by the presence of many small, immature round fibers with central nuclei and sparse myofibrils, and an increased number of satellite cells in close association with the small muscle fibers, as well as numerous rod structures. These microscopic and electron microscopic findings are interpreted as immature muscle fibers. Maturational delay or arrest implies deprivation of a development promoting factor such as a neuronal signal. Severe involvement with numerous rods was demonstrated in both diaphragm and intercostal muscles at the time of the postmortem examination, compatible with the patients respiratory failure.

The effect of starvation on brain carnitine concentration in neonatal rats

BACKGROUND We examined carnitine concentrations in fasted neonatal rat brain to evaluate the effect of starvation on fatty acid metabolism. METHODS The free- and acylcarnitine concentrations in neonatal rat brain and heart were determined after a 72-hour starvation period from the 3rd to 6th postnatal day. They were also determined in rats at 3 and 6 days of age fed normally by the mother rats as controls. RESULTS In the brain, the mean free carnitine concentration in the fasted group showed an increase similar to that in normal rats and there was no difference between the fasted and 6-day-old control rats. However, the mean acylcarnitine concentration was significantly higher in the fasted group than in the control group at both 3 and 6 days of age. Almost all of the increased acylcarnitine in the fasted group was short-chain acylcarnitine. In the heart, there was no difference in the mean free carnitine concentration between the fasted group and control group at 6 days of age. The 6-day-old rats in both the fasted and control groups showed higher levels compared to 3-day-old rats in the control group. The mean acylcarnitine concentration in the fasted group was not different from that in control group at 6 days of age, while the amount of short-chain acylcarnitine was less than that in the control group at 6 days of age. CONCLUSIONS These findings suggest that in the brain, carnitine is accumulated as a result of redistribution during starvation, and is utilized for energy supply by fatty acid oxidation.

Relationship between plasma triglycerides and apolipoprotein CII in infants during the first year of life.

Plasma triglyceride and apolipoprotein CII (apo CII) levels were measured in normal full-term infants and low-birth-weight infants at birth (from umbilical cord blood at 0 weeks), as well as at 2, 3, 4, 8, 24, and 48 weeks of age, and the relationship between plasma triglyceride and apo CII levels was studied. In both full-term and low-birth-weight infants, the plasma triglyceride and apoprotein CII levels were very low at birth, but they increased rapidly thereafter in the full-term infants and somewhat more slowly in the low-birth-weight infants. Both triglyceride and apoprotein CII levels became stable from 3 weeks of age in full-term infants and from 8 weeks in low-birth-weight infants. When the logarithmic values of triglyceride and apoprotein CII levels were compared, they showed a close correlation, and slopes of regression lines were 0.62 in full-term infants aged 0-2 weeks, 1.04 in full-term infants aged 3-48 weeks, 0.56 in low-birth-weight infants aged 0-4 weeks, and 1.04 in low-birth-weight infants aged 8-48 weeks. These results suggest that there may be some differences in triglyceride transport between full-term infants aged 0-2 weeks and 3-48 weeks as well as between low-birth-weight infants aged 0-4 weeks and 8-48 weeks.

The effect of hyperoxia on the lungs of rats deficient in essential fatty acids

Morphological alterations in the lungs of rats deficient in either or both of vitamin E and essential fatty acids were investigated after exposure to hyperoxia for 48 h. In rats deficient in both vitamin E and essential fatty acids, there was damage to type-2 alveolar cells observed as swollen mitochondria and bleb formation in the cytoplasm. None of these changes was found in rats deficient in only one of these substances. Hyperoxia in rats deficient in both substance also caused destruction of the capillary endothelial cells and edema in the interstitium. The lungs of rats deficient in only one of the substances showed some edema in the capillary endothelial cells, but not destruction, and less interstitial edema. These findings suggest that simultaneous deficiency in vitamin E and essential fatty acids facilitates lung damage in rats exposed to hyperoxia.