Comparison of olfactory and gustatory disorders in Alzheimer's disease.

Patients with Alzheimer's disease (AD) develop olfactory and gustatory disorders. However, the order of failure and relevance of the pathophysiology are unclear. We compared olfactory identification and whole mouth gustation in patients with AD to those with mild cognitive impairment (MCI) and to healthy controls (HC) and assessed correlations with pathophysiology. Patients with AD (n = 40), MCI (n = 34), and HC (n = 40) were recruited. We performed the Odor Stick Identification Test for Japanese (OSIT-J), gustatory test by the intraoral dropping method using taste solutions, Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-cognitive subscale Japanese version (ADAS-J cog), Touch Panel-type Dementia Assessment Scale (TDAS), and measurement of amyloid ß (Aß) 42 and phosphorylated tau (p-tau) 181 levels in cerebrospinal fluid (CSF). Patients with AD and MCI had lower OSIT-J scores than did the HC. The OSIT-J score was correlated with the MMSE, ADAS-J cog, TDAS, and Aß42 results. There were no significant differences in the gustatory test scores among the three groups. The gustatory test score was only correlated with the MMSE, ADAS-J cog, and TDAS results. Olfactory function decreased in AD and MCI patients and was associated with CSF biomarker levels and cognitive disorders. The results suggest that olfactory function is impaired in early stage of AD. Gustatory function was not correlated with CSF biomarkers, which suggests that it may not be impaired in early stage of AD.

The severe clinical phenotype for a heterozygous Fabry female patient correlates to the methylation of non-mutated allele associated with chromosome 10q26 deletion syndrome.

Heterozygous Fabry females usually have an attenuated form of Fabry disease, causing them to be symptomatic; however, in rare cases, they can present with a severe phenotype. In this study, we report on a 37-year-old woman with acroparesthesia, a dysmorphic face, left ventricular hypertrophy, and intellectual disability. Her father had Fabry disease and died due to chronic renal and congestive cardiac failure. Her paternal uncle had chronic renal failure and intellectual disability, and her paternal aunt was affected with congestive cardiac failure. The patient has two sisters with no significant medical illness. However, her nephew has acroparesthesia, anhidrosis, and school phobia, and her niece shows mild phenotypes. The patient's enzyme analysis showed very low α-galactosidase A (α-gal A) activity in dried blood spot (DBS), lymphocytes, and skin fibroblasts with massive excretion of Gb3 and Gb2 in urine and lyso-Gb3 in DBS and plasma. Electron microscopic examination showed a large accumulation of sphingolipids in vascular endothelial cells and keratinocytes. Chromosomal analysis and comparative genomic hybridization microarray showed 10q26 terminal deletion. Molecular data showed a novel heterozygous stop codon mutation in exon 1 of the GLA gene in her sisters and niece, and a hemizygous state in her nephew. When we checked the methylation status, we found her non-mutated allele in the GLA gene was methylated. However, the non-mutated alleles of her sisters were non-methylated, and those of her niece were partially methylated. The chromosomal and methylation study may speculate the severity of her clinical phenotypes.

Cholesterol ester storage disease with a novel LIPA mutation (L264P) that presented massive hepatomegaly: A case report.

Cholesterol ester storage disease (CESD) is an autosomal recessive disorder caused by deficient lysosomal acid lipase (LAL) activity, resulting in cholesteryl ester (CE) accumulation. CESD patients have liver disease associated with mixed dyslipidemia leading to liver failure. We here report the case of an 11-year-old male CESD patient with a novel mutation who had the chief complaint of massive hepatomegaly. The patient's liver reached to his pelvis, and his spleen was 2 cm below the costal margin. The patient had elevated serum liver enzymes and mixed dyslipidemia. The liver biopsy tissue showed characteristic CESD pathology, which included microvesicular steatosis, mild fibrosis and foamy macrophages. Electron microscopy showed a remnant cleft of CE crystals, and dried blood spot testing showed reduced LAL activity. We identified compound heterozygous mutations in the LIPA gene in this patient, namely, c.607G>C and c.791T>C. The former mutation was previously reported only in a Japanese patient, whereas the latter mutation is novel. The findings of this study suggest that LIPA gene mutations in Japanese CESD patients are different from those in Western patients. Although CESD is rare, it is likely that many patients are unrecognized or misdiagnosed, and thus the possibility of CESD should be considered in patients with hepatosplenomegaly and dyslipidemia.

Diagnostic utility of whole exome sequencing in patients showing cerebellar and/or vermis atrophy in childhood.

Cerebellar and/or vermis atrophy is recognized in various types of childhood disorders with clinical and genetic heterogeneity. Although careful evaluation of clinical features and neuroimaging can lead to correct diagnosis of disorders, their diagnosis is sometimes difficult because clinical features can overlap with each other. In this study, we performed family-based whole exome sequencing of 23 families including 25 patients with cerebellar and/or vermis atrophy in childhood, who were unable to be diagnosed solely by clinical examination. Pathological mutations of seven genes were found in ten patients from nine families (9/23, 39.1 %): compound heterozygous mutations in FOLR1, C5orf42, POLG, TPP1, PEX16, and de novo mutations in CACNA1A, and ITPR1. Patient 1A with FOLR1 mutations showed extremely low concentration of 5-methyltetrahydrofolate in the cerebrospinal fluid and serum, and Patient 6 with TPP1 mutations demonstrated markedly lowered tripeptidyl peptidase 1 activity in leukocytes. Furthermore, Patient 8 with PEX16 mutations presented a mild increase of very long chain fatty acids in the serum as supportive data for genetic diagnosis. The main clinical features of these ten patients were nonspecific and mixed, and included developmental delay, intellectual disability, ataxia, hypotonia, and epilepsy. Brain MRI revealed both cerebellar and vermis atrophy in eight patients (8/10, 80 %), vermis atrophy/hypoplasia in two patients (2/10, 20 %), and brainstem atrophy in one patient (1/10, 10 %). Our data clearly demonstrate the utility of whole exome sequencing for genetic diagnosis of childhood cerebellar and/or vermis atrophy.

The useful preliminary diagnosis of Niemann-Pick disease type C by filipin test in blood smear.

Niemann-Pick disease type C (NP-C) is an autosomal recessive lysosomal lipid storage disorder characterized with accumulation of cholesterol in endosomes and lysosomes. The diagnosis of NP-C is difficult due to its heterogeneous group of diseases. Biochemical diagnosis of NP-C is conducted by cholesterol staining with cultured skin fibroblasts and confirmed by the analysis of genetic mutations of NPC1 or NPC2 gene. Here, we report an easier biochemical diagnostic method with blood smear by filipin staining.

Clinical features of two Japanese siblings of neuronal ceroid lipofuscinosis type 1 (CLN1) complicated with Typeâ ¡ diabetes mellitus.

Neuronal ceroid lipofuscinosis type1(CLN1), is a one form of the group of neuronal ceroid lipofuscinoses (NCLs), which is a neurodegenerative disorder characterized by progressive psychomotor deterioration, ataxia, epilepsy, and visual impairment. Neurological manifestations occur at a wide range of ages, from infancy to adulthood, but are most common in infancy. The prevalence of CLN1 is unclear; however, it is very rare in Japan and Europe. In Japan, only a few cases have been reported, two of infantile- and one of juvenile-onset type. Nonetheless, the clinical characteristics of Japanese patients and their relationship with the genotype have not been sufficiently investigated. Here, we report the cases of two siblings that presented with juvenile-onset (a 22-year-old man and a 29-year-old woman) CLN1 associated with type II diabetes mellitus. In both cases, visual impairment followed by learning disability was observed from school-age, and retinitis pigmentosa was noted on ophthalmological examination. These patients presented type II diabetes mellitus during their later teenage years. Brain magnetic resonance imaging (MRI) revealed marked atrophy of the cerebrum and cerebellum. The clinical symptoms lead to suspect NCLs. Decreased PPT1 enzyme activity in dried blood spot (DBS)and leukocytes were observed, and the genetic analysis revealed heterozygous missense variants in PPT1, c.550G > A/c.664 A > G (p. Glu184Lys/p. Lys216Glu). The latter variant of this patients was novel variant. The residual enzymatic activity of PPT1 in these cases is higher than that in the infantile type. CLN1 mutant cells are known to have altered subcellular expression and localization, enhanced lipid raft-mediated endocytosis, abnormal autophagy, and mitochondrial dysfunction. Although the prevalence of diabetes mellitus is high and the possibility of coincidental complications cannot be ruled out, we concluded that mitochondrial abnormalities are involved in insulin resistance and may be implicated in the development of type II diabetes mellitus. Further studies are needed to prove the correlation between CLN1 and diabetes mellitus.

An unusual case of elderly-onset cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) with multiple cerebrovascular risk factors.

Here we report a female patient with elderly-onset cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). At age 71, she developed gait disturbance, followed by memory disturbance 1 year later. She had been treated for hypertension and diabetes mellitus for 19 years. There apparently was low penetrance of disease. Magnetic resonance imaging (MRI) findings showed typical features of CADASIL, and the R607C mutation was detected in exon 11 in NOTCH3. This case strongly indicates that CADASIL should be considered when typical findings are observed on MRI even in cases of elderly onset with multiple cerebrovascular risk factors.

Lysosomal accumulation of Trk protein in brain of GM1 -gangliosidosis mouse and its restoration by chemical chaperone.

G(M1) -gangliosidosis is a fatal neurodegenerative disorder caused by deficiency of lysosomal acid ß-galactosidase (ß-gal). Accumulation of its substrate ganglioside G(M1) (G(M1) ) in lysosomes and other parts of the cell leads to progressive neurodegeneration, but underlying mechanisms remain unclear. Previous studies demonstrated an essential role for interaction of G(M1) with tropomyosin receptor kinase (Trk) receptors in neuronal growth, survival and differentiation. In this study we demonstrate accumulation of G(M1) in the cell-surface rafts and lysosomes of the ß-gal knockout (ß-gal-/-) mouse brain association with accumulation of Trk receptors and enhancement of its downstream signaling. Immunofluorescence and subcellular fractionation analysis revealed accumulation of Trk receptors in the late endosomes/lysosomes of the ß-gal-/- mouse brain and their association with ubiquitin and p62. Administration of a chemical chaperone to ß-gal-/- mouse expressing human mutant R201C protein resulted in a marked reduction of intracellular storage of G(M1) and phosphorylated Trk. These findings indicate that G(M1) accumulation in rafts causes activation of Trk signaling, which may participate in the pathogenesis of G(M1) -gangliosidosis.

Factors responsible for neurofibrillary tangles and neuronal cell losses in tauopathy.

TgTauP301L mice that overexpress the mutant human tauP301L present in FTDP-17 reproduce neurofibrillary tangles (NFTs), neuronal cell losses, memory disturbance, and substantial phenotypic variation. To demonstrate factors responsible for NFT formation and neuronal cell losses, sets of TgTauP301L for comparison with or without NFTs and neuronal cell losses were studied with oligonucleotide microarrays. Gene expressions were altered in biological pathways, including oxidative stress, apoptosis, mitochondrial fatty acid betaoxidation, inflammatory response pathway, and complement and coagulation cascade pathways. Among 24 altered genes, increased levels of apolipoprotein D (ApoD) and neuronal PAS domain protein 4 (Npas4) and decreased levels of doublecortin (DCX) and potassium channel, voltage-gated, shaker-related subfamily, ß member 1 (Kcnab1) were found in the TgTauP301L with NFTs and neuronal cell losses, Alzheimer's brains, and tauopathy brains. Thus, many biological pathways and novel molecules are associated with NFT formation and neuronal cell losses in tauopathy brains.

Dissociation of ß-amyloid from lipoprotein in cerebrospinal fluid from Alzheimer's disease accelerates ß-amyloid-42 assembly.

Monoclonal 2C3 specific to ß-amyloid (Aß) oligomers (AßOs) enabled us to test our hypothesis that the alteration of lipoprotein-Aß interaction in the central nervous system (CNS) initiates and/or accelerates the cascade favoring Aß assembly. Immunoprecipitation of frontal cortex employing 2C3 unequivocally detected soluble 4-, 8-, and 12-mers in Alzheimer's disease (AD) brains. Immunoblot analysis of the entorhinal cortex employing 2C3 revealed that the accumulation of soluble 12-mers precedes the appearance of neuronal loss or cognitive impairment and is enhanced as the Braak neurofibrially tangle (NFT) stages progress. The dissociation of soluble Aß from lipoprotein particles occurs in cerebrospinal fluid (CSF), and the presence of lipoprotein-free oligomeric 2C3 conformers (4- to 35-mers) was evident, which mimic CNS environments. Such CNS environments may strongly affect conformation of soluble Aß peptides, resulting in the conversion of soluble Aß(42) monomers into soluble Aß(42) assembly. The findings suggest that functionally declined lipoproteins may accelerate the generation of metabolic conditions leading to higher levels of soluble Aß(42) assembly in the CNS.

Amyloid ß accelerates phosphorylation of tau and neurofibrillary tangle formation in an amyloid precursor protein and tau double-transgenic mouse model.

In Alzheimer's disease, Aß deposits are considered the initial cardinal events that induce tauopathy secondarily. However, the relationship between Aß amyloidosis and tauopathy has not been determined in detail. We produced double transgenic mice, 2×TgTau(+/-) APP(+/-) , by mating Tg2576 mice that exhibit Aß amyloidosis and TgTauP301L mice that show tauopathy, and statistically analyzed the effect of Aß accumulation on tauopathy. There was no significant difference in theprogression of Aß accumulation among 2×TgTau(+/-) APP(+/-) and 1×TgTau(-/-) APP(+/-) , and tau accumulation among 2×TgTau(+/-) APP(+/-) and 1×Tg Tau(+/-) APP(-/-) . The appearance rates of phosphorylated tau developing in neurons and processes were significantly accelerated in 2×TgTau(+/-) APP(+/-) mice compared with those in 1×TgTau(+/-) APP(-/-) mice at 23 months of age. Accumulation of phosphorylated and confomationally altered tau and GSK3ß in neuronal processes was accelerated in the white matter in 2×TgTau(+/-) APP(+/-) . The level of phosphorylated tau in the sarkosyl-insoluble fraction was increased in 2×TgTau(+/-) APP(+/-) brains compared with that in 1×TgTau(+/-) APP(-/-) brains. Thus, Aß amyloid partially enhances tauopathy through accumulation of insoluble, phosphorylated, and conformationally changed tau in neuronal cytoplasm and processes in the late stage.

Aberrant promoter methylation and expression of the imprinted PEG3 gene in glioma.

Glioma includes astrocytoma, oligodendroglioma, ependymoma and glioblastoma. We previously reported the epigenetic silencing of paternally expressed gene 3 (PEG3) in glioma cell lines. In this study, we investigated methylation of an exonic CpG island in the promoter region and the expression of PEG3 gene in 20 glioma and 5 non-tumor tissue samples. We found wide variations in the methylation level. Hypomethylaiton and hypermethylation was found in 3 and 4 glioma tissue samples, respectively. Monoallelic expression, which is an evidence of an imprinted gene, was maintained in eight out of nine informative cases which have T/C polymorphisms in PEG3. The lower gene expression, which suggested epigenetic silencing of PEG3, was confirmed statistically in glioblastoma using quantitative reverse-transcription polymerase chain reaction. Interestingly, we found higher expression of PEG3 in two out of three oligodendrogliomas. A negative correlation between the methylation level and gene expression was shown by regression analysis. These results suggest that the abnormal regulation of PEG3 is associated with several glioma subtypes and that it plays an important role in tumorigenesis.

Enhanced autophagy and mitochondrial aberrations in murine G(M1)-gangliosidosis.

G(M1)-gangliosidosis is an autosomal recessive lysosomal lipid storage disorder, caused by mutations of the lysosomal beta-galactosidase (beta-gal) and results in the accumulation of G(M1). The underlying mechanisms of neurodegeneration are poorly understood. Here we demonstrate increased autophagy in beta-gal-deficient (beta-gal(-/-)) mouse brains as evidenced by elevation of LC3-II and beclin-1 levels. Activation of autophagy in the beta-gal(-/-) brain was found to be accompanied with enhanced Akt-mTOR and Erk signaling. In addition, the mitochondrial cytochrome c oxidase activity was significantly decreased in brains and cultured astrocytes from beta-gal(-/-) mouse. Mitochondria isolated from beta-gal(-/-) astrocytes were morphologically abnormal and had a decreased membrane potential. These cells were more sensitive to oxidative stress than wild type cells and this sensitivity was suppressed by ATP, an autophagy inhibitor 3-methyladenine and a pan-caspase inhibitor z-VAD-fmk. These results suggest activation of autophagy leading to mitochondrial dysfunction in the brain of G(M1)-gangliosidosis.

Cerebrospinal fluid biomarkers of Alzheimer's disease are associated with carotid plaque score and hemodynamics in intra- and extra-cranial arteries on ultrasonography.

Carotid plaque score (PS) and hemodynamic abnormalities in intra- and extra-cranial arteries are related to Alzheimer's disease (AD) progression. As these parameters are measured conveniently and non-invasively by ultrasonography, we examined their association with cerebral spinal fluid (CSF) AD biomarkers amyloid ß (Aß) and phosphorylated tau (p-tau). Carotid PS, mean flow velocity (MFV) in multiple intra- and extra-cranial arteries, CSF Aß42 and p-tau, neurocognitive function (assessed by the Mini-Mental State Examination and Alzheimer's Disease Assessment Scale-cognitive subscale, Japanese version), and blood lipids (total cholesterol, HDL cholesterol, LDL cholesterol, and triglyceride) were measured in AD patients (n = 42), mild cognitive impairment patients (n = 20), and cognitively normal controls (n = 18). The results were also compared among groups defined by PS range. After adjusting for blood lipids as covariates, Aß42 was higher in the PS = 1.1-2.0 mm group than in the higher PS groups (2.1-3.0, 3.1-5.0, 5.1-7.0, and >7.0 mm). However, subjects with very low PS (<1.1 mm) also had a low mean CSF Aß42. Alternatively, CSF p-tau181 did not differ between PS groups. In multiple regression analysis, Aß42 was not associated with MFVs; however, CSF p-tau181 showed a significant association with the MFV of the internal carotid and basilar arteries. Findings suggest that carotid plaque formation may accelerate Aß42 deposition, although it is not necessary for deposition. Hemodynamics abnormalities may cause increased CSF p-tau181. Ultrasonographic evaluation of PS and arterial hemodynamics may be a useful noninvasive method for estimating AD pathology.

Identification of a novel GLA mutation (F69 L) in a Japanese patient with late-onset Fabry disease.

Fabry disease is an X-linked recessive inborn error of glycosphingolipid catabolism caused by a mutation in the GLA gene. We sequenced the α-galactosidase A gene (GLA) of a patient who had been clinically diagnosed with late-onset Fabry disease. Abundant globotriaosylceramide was present in his urine, which indicated typical Fabry disease. Here, we report a novel hemizygous mutation, c.207C>A (Phe69 Leu), which caused a mild/late-onset form of Fabry disease.

Disease modifying therapies for Alzheimer's disease targeting Aß oligomers: implications for therapeutic mechanisms.

Several lines of evidence indicate that amyloid ß (Aß), particularly Aß oligomers (AßOs), plays a causative role in Alzheimer's disease. However, the mechanisms underlying the action of an anti-AßO antibody to clarify the toxic action of AßOs remain elusive. Here, we showed that the anti-AßO antibody (monoclonal 72D9) can modify the Aß aggregation pathway. We also found that 72D9 directly sequesters both extracellular and intraneuronal AßOs in a nontoxic state. Thus, therapeutic intervention targeting AßOs is a promising strategy for neuronal protection in Alzheimer's disease.

Sortilin is required for toxic action of Aß oligomers (AßOs): extracellular AßOs trigger apoptosis, and intraneuronal AßOs impair degradation pathways.

AIMS: We investigated the pathological relevance of the "Aß oligomer (AßO) cascade hypothesis" in 3xTg-AD mice. This study was also designed to elucidate the molecular mechanism underlying the toxic action of AßOs. MAIN METHODS: To target the extracellular AßOs in vivo, a monoclonal antibody specific for AßOs was developed using a novel method. Monoclonal 72D9 was intravenously administered to aged 3xTg-AD mice bearing the human AD pathology to investigate the relevance of the AßO cascade hypothesis. To further identify the AßO-binding molecule on the cell surface, small interfering RNA (siRNA) for sortilin was transfected into SH-SY5Y cells. The sortilin-dependent molecular mechanism underlying toxic action of AßOs and/or AßO endocytosis was also assessed in cultured cortical neurons forming synapses. KEY FINDINGS: The 72D9 immunotherapy of aged 3xTg-AD mice revealed that extracellular and intraneuronal AßOs are related, and that intraneuronal AßOs act upstream of tau. We also found that extracellular AßOs first act as a sortilin ligand, and then induce p75(NTF)-mediated apoptosis, endocytosis-induced attenuation of autophagy, or accumulation of AßOs in autophagosomes. SIGNIFICANCE: Taken together, these findings provide novel lines of evidence that sortilin governs the toxic action of extracellular AßOs, which affects the degradation and/or clearance of either intraneuronal AßOs or tau. Thus, therapeutic intervention targeting extracellular AßOs themselves or for preventing the interaction between intraneuronal AßOs and tau is a promising strategy to be developed for AD treatment.

Extracellular and intraneuronal HMW-AbetaOs represent a molecular basis of memory loss in Alzheimer's disease model mouse.

BACKGROUND: Several lines of evidence indicate that memory loss represents a synaptic failure caused by soluble amyloid ß (Aß) oligomers. However, the pathological relevance of Aß oligomers (AßOs) as the trigger of synaptic or neuronal degeneration, and the possible mechanism underlying the neurotoxic action of endogenous AßOs remain to be determined. RESULTS: To specifically target toxic AßOs in vivo, monoclonal antibodies (1A9 and 2C3) specific to them were generated using a novel design method. 1A9 and 2C3 specifically recognize soluble AßOs larger than 35-mers and pentamers on Blue native polyacrylamide gel electrophoresis, respectively. Biophysical and structural analysis by atomic force microscopy (AFM) revealed that neurotoxic 1A9 and 2C3 oligomeric conformers displayed non-fibrilar, relatively spherical structure. Of note, such AßOs were taken up by neuroblastoma (SH-SY5Y) cell, resulted in neuronal death. In humans, immunohistochemical analysis employing 1A9 or 2C3 revealed that 1A9 and 2C3 stain intraneuronal granules accumulated in the perikaryon of pyramidal neurons and some diffuse plaques. Fluoro Jade-B binding assay also revealed 1A9- or 2C3-stained neurons, indicating their impending degeneration. In a long-term low-dose prophylactic trial using active 1A9 or 2C3 antibody, we found that passive immunization protected a mouse model of Alzheimer's disease (AD) from memory deficits, synaptic degeneration, promotion of intraneuronal AßOs, and neuronal degeneration. Because the primary antitoxic action of 1A9 and 2C3 occurs outside neurons, our results suggest that extracellular AßOs initiate the AD toxic process and intraneuronal AßOs may worsen neuronal degeneration and memory loss. CONCLUSION: Now, we have evidence that HMW-AßOs are among the earliest manifestation of the AD toxic process in mice and humans. We are certain that our studies move us closer to our goal of finding a therapeutic target and/or confirming the relevance of our therapeutic strategy.

Intracerebral cell transplantation therapy for murine GM1 gangliosidosis.

We performed a cell transplantation study to treat the brain involvement in lysosomal storage diseases. We used acid beta-galactosidase knock-out mice (BKO) from C57BL/6 as recipients. To minimize immune responses, we used cells derived from transgenic mice of C57BL/6 overexpressing the normal human beta-galactosidase. Fetal brain cells (FBC), bone marrow-derived mesenchymal stem cells (MSC), and mixed FBC and MSC cells were prepared and injected into the ventricle of newborn BKO mouse brain. The mice were examined at 1, 2, 4, and 8 weeks and 6 months after injection. In each experiment, the injected cells migrated into the whole brain effectively and survived for at least 8 weeks. Decrease in ganglioside GM1 level was also observed. FBC could survive for 6 months in recipient brain. However, the number of transplanted FBC decreased. In the brains of MSC- or mixed cell-treated mice, no grafted cells could be found at 6 months. To achieve sufficient long-term effects on the brain, a method of steering the immune response away from cytotoxic responses or of inducing tolerance to the products of therapeutic genes must be developed.

An unusual case of chronic relapsing tetanus associated with mandibular osteomyelitis.

A 55-year-old man underwent radiation therapy due to malignant lymphoma of the neck. Eight years after the therapy he developed tetanus. It appears that the radiation therapy resulted in mandibular necrosis, and that this lesion may have been the infectious focus of tetanus. Treatment with penicillin G was very effective in the acute stage, and chronic administration of metronidazole prevented relapse of the disease. However in spite of injections of tetanus toxoid, symptoms of tetanus returned when the administration of metronidazole was discontinued because the infectious focus could not be completely removed. This is the first report of chronic relapsing tetanus associated with radiation-induced mandibular osteomyelitis, and demonstrates that tetanus can occur due to mandibular focus but the chronic administration of metronidazole can prevent relapse.