Biomedical subjects
Publications and source records attributed to Atsuo Nezu.
Norovirus is a common cause of gastroenteritis. We describe the case of a 23-month-old girl with encephalopathy possibly associated with norovirus infection. The viral genome was detected in stool, serum and cerebrospinal fluid (CSF) by reverse transcription polymerase chain reaction. This is the first report of encephalopathy potentially caused by norovirus as indicated by the presence of the virus genome in CSF.
We present a 10-year-old female diagnosed having hereditary neuropathy with liability to pressure palsies (HNPP). She had suffered from acute, recurrent monoplegic episodes affecting both the sciatic nerves and the left brachial plexus since the age of 7 years. The paresis seemed to be triggered by hiking and athletic training. Electrophysiological studies showed a conduction block in the proximal portions of affected nerves. The FISH method disclosed a deletion of the peripheral myelin protein 22 gene. This school child having HNPP is considered to be susceptible to the influence of abundant physical training, rather than minor trauma or compression at sites of entrapment of peripheral nerves.
Charcot-Marie-Tooth disease (CMT) has been classified into two types, CMT1 and CMT2, demyelinating and axonal forms, respectively. CMT2 has been further subdivided into eight groups by linkage studies. CMT2A is linked to chromosome 1p35-p36 and mutation in the kinesin family member 1B-beta (KIF1B) gene had been reported in one pedigree. However, no mutation in KIF1B was detected in other pedigrees with CMT2A and the mutations in the mitochondrial fusion protein mitofusin 2 (MFN2) gene were recently detected in those pedigrees. MFN2, a mitochondrial transmembrane GTPase, regulates the mitochondrial network architecture by fusion of mitochondria. We studied MFN2 in 81 Japanese patients with axonal or unclassified CMT and detected seven mutations in seven unrelated patients. Six of them were novel and one of them was a de novo mutation. Most mutations locate within or immediately upstream of the GTPase domain or within two coiled-coil domains, which are critical for the functioning or mitochondrial targeting of MFN2. Formation of a mitochondrial network would be required to maintain the functional peripheral nerve axon.
We experienced the case of a boy suffering from acute disseminated encephalomyelitis and concomitant acute glomerulonephritis. The multiple lesions observed on MR images, which located mainly in the cortical gray matter, quickly responded to methyl prednisolone pulse therapy. Renal biopsy confirmed the diagnosis of poststreptococcal acute glomerulonephritis. Streptococcus pyogenes was identified by pharyngeal culture, and the infection was serologically confirmed. We speculated that S. pyogenes infection was coincidentally involved in both diseases.
Pediatricians are often faced with both bad temper and decreased daily activity in children with persistent nephrotic syndrome. These problems, which might affect both mental and physical development, have been explained as a consequence of general fatigue due to systemic edema and/or long-term hospitalization. However, other factors, such as cerebral hypoperfusion, may be involved. We experienced a case of a boy with steroid-resistant nephrotic syndrome who showed diffuse cerebral hypoperfusion on single photon emission computed tomography. Diffuse cerebral hypoperfusion dramatically resolved as the nephrotic syndrome remitted. His bad temper, decreased daily activity, and delay of speech and motor development also improved. In our patient, cerebral hypoperfusion might have been associated with his mental problems, physical problems, and delayed development of speech.
We report here a 25-year-old girl with Friedreich's ataxia (FA) who showed slowly progressive ataxia, deep sensory disturbance and loss of large myelinated fiber in the sural nerve. There was no evidence of cerebellar atrophy or abnormal values of vitamin E, albumin, CK, and gamma-globulin in the serum. Except for mild mental retardation, her clinical and laboratory findings were consistent with those of FA. However, she had no abnormal GAA trinucleotide repeat expansion on chromosome 9q13, unlike typical FA patients in Europe. Her cardiac muscle is not involved instead of 20 years have passed since her ataxia developed. She is considered to belong to a specific type of FA which lacks cardiac muscle involvement and abnormal gene encoding frataxin.