Establishment and characterization of an Epstein-Barr virus-transformed B cell line, KM/C8, from a patient with infantile sialic acid storage disease

Nakano et al. have recently reported a Japanese case of infantile sialic acid storage disease [C. Nakano, Y. Hirabayashi, K. Ohno, T. Yano, T. Mito, M. Sakurai, Brain Dev., 18 (1996) 153-156]. For further etiological analysis of this disease, we prepared the Epstein-Barr virus (EBV)-transformed cell line (LCL) from the peripheral lymphocytes of this patient and performed initial characterization of the cells. Electron microscopy of the cells showed that the cells contained many vacuoles and swelled lysosomes. Cytochemical staining with sialic acid-specific lectin, Limax flavus agglutinin (LFA), showed strong staining on membranes and subcellular organelles on the patient-derived cells, whereas LCL from a normal person was only weakly stained. The cells from the patient contained 5.5-7.3 nmol/107 cells of free N-acetyl neuraminic acid, whereas three strains of LCLs derived from normal persons contained 1 nmol/107 cells. The culture supernatant of LCL from the patient contained 144 nmol/ml of free N-acetyl neuraminic acid, whereas the LCL culture supernatant from normal persons contained 57-73 nmol/ml of free sialic acid, which was the same or only at a slightly higher level than the fresh medium. In addition, cellular acidic sialidase measured as 4-methylumbelliferyl sialidase was elevated (107 nmol 4-methylumbelliferon released/mg cellular protein/60 min). The EBV-LCL from an ISSD patient is considered to remain as the abnormality of the cell donor.

New autosomal-recessive syndrome of Leber congenital amaurosis, short stature, growth hormone insufficiency, mental retardation, hepatic dysfunction, and metabolic acidosis

We report on a new autosomal-recessive syndrome in 4 Japanese children in 2 families. The key manifestations are Leber congenital amaurosis, short stature, growth hormone insufficiency, mental retardation, hepatic dysfunction, metabolic acidosis, and autosomal-recessive inheritance. There were no consanguineous marriages. Abnormal eye movements were noticed neonatally, and ophthalmological examinations showed no visual acuity, pigmentary retinal degeneration, and nonrecordable electroretinograms in all cases. Inadequate weight gain and short stature gradually became apparent after birth, and at present the height range is -4.6 - -7.2 SD (standard deviations). Developmental delay was noted at age 4 months, and the developmental quotient is 50-70 at present. Deterioration of development and convulsions were not recognized. Elevated serum aminotransferase levels and metabolic acidosis were also found at age 4 months. Proximal renal tubular acidosis was clarified by bicarbonate tolerance tests in 1 case, and may have caused metabolic acidosis. Growth hormone secretion was insufficient by insulin tolerance test in 3 cases. One year of growth hormone therapy in 2 cases did not affect growth velocity. Hepatic dysfunction and metabolic acidosis ameliorated later. No renal cysts were found. A cranial computed tomographic scan and magnetic resonance imaging showed normal findings. Amino acids, organic acids, and very long chain fatty acid levels in plasma were all normal in the 3 cases examined. Histopathological and mitochondrial DNA analyses showed no evidence of mitochondrial disorders.

A Japanese case of infantile sialic acid storage disease

We report a 4-year-old Japanese girl with infantile sialic acid storage disease. She presented with failure to thrive, coarse facial features, hepatosplenomegaly, severe mental retardation and spastic quadriplegia. Electron microscopic examination of cultured skin fibroblasts revealed multiple vacuoles and inclusion material representing distended lysosomes, thus suggesting a lysosomal storage disorder. A high concentration of free sialic acid was present in the urine and cultured fibroblasts, but bound sialic acid was not increased. The activity of a variety of lysosomal enzymes was not diminished. The MRI findings included brain atrophy and a diffuse high signal in the cerebral white matter and low signal in the basal ganglia on T2-weighted images. To our knowledge, this is the first case of infantile sialic acid storage disease described in a non-Caucasian family.

Carnitine concentration during the development of human tissues

The different carnitine storage patterns in developing human tissues (skeletal muscle, liver and brain) were demonstrated. The carnitine concentration was high in the skeletal muscle and liver relative to other tissues during preterm gestation, and the skeletal muscle carnitine concentration increased with growth. On the other hand, the brain carnitine concentration was low. The brain contained a larger proportion of acylcarnitine than of free carnitine from midgestation, while the skeletal muscle and liver contained larger concentrations of free carnitine than of acylcarnitine. These different carnitine concentrations and composition patterns in the skeletal muscle, liver and brain may be related to maturation of the potential carnitine reserve and to metabolic functions, such as fatty acid utilization and the reservoir of acetyl units, in each developmental tissue.

Insulin binding and internalization in cultured fibroblasts from myotonic muscular dystrophy

The binding and internalization of insulin receptors were investigated in 8 adult form and 6 early-onset myotonic muscular dystrophy (MMD) patients and in age- and sex-matched controls, using cultured skin fibroblasts to avoid the in vivo milieu of donors. The specific insulin binding in the presence of [125I]insulin alone at pH 7.4 and pH 8.0 in MMD patients was not significantly different from that of the controls. The competition curves of insulin binding and the Scatchard plots in MMD and control fibroblasts were similar. Insulin receptor affinity in MMD patients was not different from that in the controls. In the presence of chloroquine, a lysosomotropic agent, the rate of increase in cell-associated radioactivity was similar in both MMD groups and controls. Thus, the normal binding and internalization of the insulin receptors in cultured skin fibroblasts from MMD patients suggest that the insulin receptors are not determined by the pathological genetic factors in MMD. Furthermore, the abnormal insulin binding to freshly isolated cells, reported previously, may be a reflection of environmental factors rather than a genetically determined cellular abnormality in MMD.

Multimodality evoked potentials in progression of metachromatic leukodystrophy

A 2-yr-3-mo-old girl with metachromatic leukodystrophy (MLD) was examined using serial multiple electrophysiological procedures. Sensory nerve conduction velocity was delayed earlier and more severely than motor nerve conduction velocity. Visual evoked potentials (VEPs) showed prolonged latency of wave IV. Auditory brainstem responses (ABRs) showed prolonged latency of waves I and V, and the I-V interval. As to the interpeak latency of somatosensory evoked potentials (SEPs), the P9-P14 and the P14-N20 intervals were prolonged on admission. Two months later, both intervals were more prolonged, but the prolongation of the P9-P14 interval was the most prominent. The demyelination in our case may have started in the cerebral white matter, progressed to the peripheral nerves, and at last via the spinal root reached the brainstem. An electrophysiological follow-up study may be valuable in the understanding of the progressive pathological changes and in the evaluation of therapeutic measures.

Fibroblasts from patients with myotonic muscular dystrophy: cholesterol requirement for proliferation and sensitivity to polyene antibiotics

The genetic defect in myotonic muscular dystrophy (MMD) remains obscure. From the evidence that drugs blocking cholesterol biosynthesis induce myotonia and increased serum concentrations of deoxycholic acids are common among patients with MMD, evidence of the abnormal sterol metabolism in MMD fibroblasts was sought by comparing them with fibroblasts from control individuals and patients with Duchenne muscular dystrophy (DMD). Although early-onset type MMD and DMD fibroblasts have lower maximal cell densities than fibroblasts from age-matched control individuals do in medium containing 10% fetal bovine serum, we could not reveal any abnormalities in exogeneous cholesterol requirements for proliferation of MMD fibroblasts. This suggests that the sterol biosynthetic pathway in MMD fibroblasts is grossly intact. Furthermore, no difference were observed in sensitivities to polyene antibiotics, which bind to membrane sterols and presumably damage the cell membrane.

[Experience with high-dose methotrexate therapy for malignant solid tumors]

Thirteen patients with malignant solid tumors, mainly osteogenic sarcomas, were treated by high-dose MTX therapy, 50-400 mg/kg, in a total of 72 cycles. It has been proved that this therapy was relatively safe provided careful clinical surveillance were assured. Of 8 patients with osteogenic sarcomas, 6 had no metastatic lesions on the chest X-rays before this therapy: three were alive without any evidence of disease for 18-25 months after high-dose MTX therapy. In some cases of other malignant solid tumors, particularly intracranial tumors, clinical efficacy was observed. Dose-time relationships, etc. should further be studied for more therapeutic efficacies of high-dose MTX therapy.