Immune complexome analysis reveals the presence of immune complexes and identifies disease-specific immune complex antigens in saliva samples from patients with Sjögren's syndrome.

Sjögren's syndrome (SS) is a chronic autoimmune disease that mainly damages the salivary and lacrimal glands. Immune complex (IC) formation triggers local inflammation through IC deposition and decreased antigen function. Some ICs can leak from the lesion and into the saliva, but no salivary ICs have been reported to date. We used immune complexome analysis to comprehensively identify antigens incorporated into IC (IC-antigens) in saliva samples from patients with SS (n = 9) or with xerostomia (n = 7). Neutrophil defensin 1 (67%), small proline-rich protein 2D (67%), myeloperoxidase (44%), neutrophil elastase (44%), cathepsin G (33%), nuclear mitotic apparatus 1 (33%) and phosphatidylinositol 4-phosphate 3-kinase C2 domain-containing subunit gamma (33%) were identified as new IC-antigens specifically and frequently detected in the saliva of SS patients. Of these, neutrophil defensin 1, myeloperoxidase, neutrophil elastase and cathepsin G are neutrophil intracellular proteins, which suggests that repeated destruction of neutrophils due to abnormal autoimmunity may be involved in the pathogenesis of SS. We also analyzed serum samples from three SS patients. There was little overlap of IC-antigens between two of the samples (fewer than 30% of the IC-antigens in the saliva samples), suggesting that many ICs are formed locally and independently of the circulation. In addition, we found that four SS-specific salivary antigens show sequence homology with several proteins of oral microbiomes but no antigen has homology with Epstein-Barr virus proteins. The homology between some IC-antigens and oral microbiome proteins may indicate the impact of oral infection on local autoimmunity through molecular mimicry theory.

CD73 complexes with emmprin to regulate MMP-2 production from co-cultured sarcoma cells and fibroblasts.

BACKGROUND: Interaction between cancer cells and fibroblasts mediated by extracellular matrix metalloproteinase inducer (emmprin, CD147) is important in the invasion and proliferation of cancer cells. However, the exact mechanism of emmprin mediated stimulation of matrix metalloprotease-2 (MMP-2) production from fibroblasts has not been elucidated. Our previous studies using an inhibitory peptide against emmprin suggested the presence of a molecule on the cell membrane which forms a complex with emmprin. Here we show that CD73 expressed on fibroblasts interacts with emmprin and is a required factor for MMP-2 production in co-cultures of sarcoma cells with fibroblasts. METHODS: CD73 along with CD99 was identified by mass spectrometry analysis as an emmprin interacting molecule from a co-culture of cancer cells (epithelioid sarcoma cell line FU-EPS-1) and fibroblasts (immortalized fibroblasts cell line ST353i). MMP-2 production was measured by immunoblot and ELISA. The formation of complexes of CD73 with emmprin was confirmed by immunoprecipitation, and their co-localization in tumor cells and fibroblasts was shown by fluorescent immunostaining and proximity ligation assays. RESULTS: Stimulated MMP-2 production in co-culture of cancer cells and fibroblasts was completely suppressed by siRNA knockdown of CD73, but not by CD99 knockdown. MMP-2 production was not suppressed by CD73-specific enzyme inhibitor (APCP). However, MMP-2 production was decreased by CD73 neutralizing antibodies, suggesting that CD73-mediated suppression of MMP-2 production is non-enzymatic. In human epithelioid sarcoma tissues, emmprin was immunohistochemically detected to be mainly expressed in tumor cells, and CD73 was expressed in fibroblasts and tumor cells: emmprin and CD73 were co-localized predominantly on tumor cells. CONCLUSION: This study provides a novel insight into the role of CD73 in emmprin-mediated regulation of MMP-2 production.

Expression of laminin 5-γ2 chain in cutaneous squamous cell carcinoma and its role in tumour invasion.

BACKGROUND: Laminin-5 (Ln5), a heterotrimer composed of three chains (α3, ß3, and γ2), is a major component of the basement membrane in most adult tissues. One of the chains, Ln5-γ2, is a marker of invasive tumours because it is frequently expressed as a monomer in malignant tumours. Recent studies from our laboratories detected higher levels of Ln5-γ2 expression in basal cell carcinoma (BCC) than in trichoblastoma. Furthermore, Ln5-γ2 overexpression tended to correlate with aggressiveness in BCC. METHODS: In this study, we compared the expression of Ln5-γ2 in invasive squamous cell carcinoma (SCC, n = 62) of the skin to that in preinvasive Bowen's disease (BD, n = 51), followed by analysis of the role of Ln5-γ2 in cancer invasion in vitro. RESULTS: Immunohistochemically, the proportion of SCC cases (86%) strongly positive for Ln5-γ2 expression was higher than that of BD (16%). Real-time RT-PCR showed Ln5-γ2 overexpression in SCC cell line, A431, compared with normal keratinocyte cell line, HaCaT. Ln5-γ2 monomer and proteolytically cleaved, biologically active fragments of Ln5-γ2 were identified in SCC tumour extracts. In in vitro raft cultures, which simulate in vivo conditions, Ln5-γ2 siRNA significantly suppressed epidermal growth factor (EGF)-stimulated A431 cell invasion. CONCLUSION: Our results indicate that Ln5-γ2 has a role in cutaneous SCC invasion.

Biological pathways and in vivo antitumor activity induced by Atiprimod in myeloma.

Atiprimod (Atip) is a novel oral agent with anti-inflammatory properties. Although its in vitro activity and effects on signaling in multiple myeloma (MM) have been previously reported, here we investigated its molecular and in vivo effects in MM. Gene expression analysis of MM cells identified downregulation of genes involved in adhesion, cell-signaling, cell cycle and bone morphogenetic protein (BMP) pathways and upregulation of genes implicated in apoptosis and bone development, following Atip treatment. The pathway analysis identified integrin, TGF-beta and FGF signaling as well as Wnt/beta-catenin, IGF1 and cell-cycle regulation networks as being most modulated by Atip treatment. We further evaluated its in vivo activity in three mouse models. The subcutaneous model confirmed its in vivo activity and established its dose; the SCID-hu model using INA-6 cells, confirmed its ability to overcome the protective effects of BM milieu; and the SCID-hu model using primary MM cells reconfirmed its activity in a model closest to human disease. Finally, we observed reduced number of osteoclasts and modulation of genes related to BMP pathways. Taken together, these data demonstrate the in vitro and in vivo antitumor activity of Atip, delineate potential molecular targets triggered by this agent, and provide a preclinical rational for its clinical evaluation in MM.

The value of tumor volume in surgically resected non-small cell lung cancer.

BACKGROUND: The aim of this study was to evaluate whether or not tumor volume (TV) has an impact on survival in non-small cell lung cancer. METHODS: In a retrospective analysis of 385 cases with NSCLC who underwent curative surgery between 1994 and 2003, we calculated the tumor volume by using an ellipsoidal formula. The patients were grouped according to TV as determined by histograms. Gender, age, histology, nodal involvement, size, and TV were analyzed. Multivariate analysis by Cox's proportional hazards regression model was performed to identify the prognosis. RESULTS: Cases of N0 showed a significantly lower TV than cases with other N statuses (p < 0.05). A significant difference was also observed between TV and histology or gender. The 189 patients belonging to the small volume group (SVG) (range, 0.105 to 9.265 cm3) had a significantly better overall survival rate than the other 196 patients in the large volume group (LVG) (9.266-366.522 cm3). With univariate analysis, gender, age, nodal involvement, size, and TV were significantly associated with prognosis. Multivariate analysis showed that only gender (p = 0.0184) and nodal involvement (p = 0.0001) were significantly independent prognostic factors. The size factor was not significant (p = 0.5285). However, TV was not an independent factor, but trending toward significance (p = 0.0801). CONCLUSIONS: Although TV provides no independent prognostic information with multivariate analysis, TV in NSCLC should be considered using volumetric measurement with a three-dimensional CT approach prior to surgery or treatment planning.

Antimyeloma activity of two novel N-substituted and tetraflourinated thalidomide analogs.

Thalidomide alone or in combination with steroids has significant activity in multiple myeloma (MM). However, given its teratogenic potential, analogs have been synthesized, retaining the anti-MM activity without these side effects. We examined the anti-MM activity of two thalidomide analogs, CPS11 and CPS49. Direct cytotoxicity of the drugs on myeloma cell lines and patient myeloma cells was examined using thymidine uptake. Tumor cell apoptosis was evaluated by flow cytometry as well as Western blotting for caspase and PARP cleavage. Cellular signaling events were examined by immunoblotting for phosphorylated proteins. Both drugs inhibit proliferation of several MM cell lines sensitive and resistant to conventional therapies. They decrease secretion of IL-6, IGF, and VEGF by marrow stromal cells. Importantly, they inhibit proliferation of MM cells adherent to stromal cells. These drugs induce caspase-mediated apoptosis in MM cell lines, as well as patient MM cells. They inhibit the PI3K/Akt and JAK/STAT (signal transducers and activators of transcription) pathways in MM cells and are antiangiogenic in matrigel-based assays. CPS11 and CPS49 have potent antimyeloma activity and can overcome protective effects of the tumor microenvironment. They have potent antiangiogenic activity and direct effect on bone marrow stroma. These encouraging preclinical data provide the basis for further evaluation in the clinic.

Imbalance between apoptosis and telomerase activity in myelodysplastic syndromes: possible role in ineffective hemopoiesis.

The myelodysplastic syndromes (MDS) are a group of disorders characterized by peripheral pancytopenia despite normo- or hyper-cellular bone marrow. This is thought to be due to apoptosis of hematopoietic bone marrow cells, resulting in ineffective hematopoiesis. The heterogeneous nuclear ribonucleoprotein (hnRNP) B1 is involved in pre-mRNA processing and binds to telomeric cDNA repeats. The hnRNP B1 is a marker for early cancer. The aim of our study was to clarify the relationships between prognosis and apoptosis, telomerase activity (TA) and hnRNP expression in the bone marrow. The subjects were 51 patients with MDS, including patients with refractory anemia (RA) (n = 32), refractory anemia with ringed sideroblasts (RARS) (n = 1), refractory anemia with excess blasts (RAEB) (n = 7), refractory anemia with excess blasts in transformation (RAEB-t) (n = 8) and chronic myelomonocytic leukemia (CMMoL) (n = 3). We also studied 6 cases with acute myelogenous leukemia (AML) arising from MDS (AML-MDS) and 10 control subjects. Bone marrow biopsies were stained immunohistochemically for caspase-3 (marker of apoptotic activity) and human telomerase reverse transcriptase (hTERT), and hnRNP B1. Fatal pancytopenia was the cause of death in 19 of the 51 patients. The caspase-3 positive cell rate was higher in MDS (16.3%) than in controls (4.4%) and AML-MDS (0.5%). The percentage of hnRNP B1-positive cells was higher in MDS (15.3%) and AML-MDS (56.3%) than in controls (5.6%). In MDS, hnRNP B1 levels were higher in RAEB and RAEB-t subtypes than in RA and RARS. The percentage of hTERT-positive cells was higher in AML-MDS (50.0%) than in controls (20.2%) and MDS (23.6%). Our findings suggest that activation of apoptosis occurs in MDS in the absence of hTERT expression, implicating high apoptosis in the absence of high TA with ineffective hematopoiesis. Poor prognosis correlated with higher caspase-3 and lower hTERT rates. In MDS, hnRNP B1 activity may be associated with leukemic transformation.

Autophagosome requires specific early Sec proteins for its formation and NSF/SNARE for vacuolar fusion.

Double membrane structure, autophagosome, is formed de novo in the process of autophagy in the yeast Saccharomyces cerevisiae, and many Apg proteins participate in this process. To further understand autophagy, we analyzed the involvement of factors engaged in the secretory pathway. First, we showed that Sec18p (N-ethylmaleimide-sensitive fusion protein, NSF) and Vti1p (soluble N-ethylmaleimide-sensitive fusion protein attachment protein, SNARE), and soluble N-ethylmaleimide-sensitive fusion protein receptor are required for fusion of the autophagosome to the vacuole but are not involved in autophagosome formation. Second, Sec12p was shown to be essential for autophagy but not for the cytoplasm to vacuole-targeting (Cvt) (pathway, which shares mostly the same machinery with autophagy. Subcellular fractionation and electron microscopic analyses showed that Cvt vesicles, but not autophagosomes, can be formed in sec12 cells. Three other coatmer protein (COPII) mutants, sec16, sec23, and sec24, were also defective in autophagy. The blockage of autophagy in these mutants was not dependent on transport from endoplasmic reticulum-to-Golgi, because mutations in two other COPII genes, SEC13 and SEC31, did not affect autophagy. These results demonstrate the requirement for subgroup of COPII proteins in autophagy. This evidence demonstrating the involvement of Sec proteins in the mechanism of autophagosome formation is crucial for understanding membrane flow during the process.

Electrophysiological studies and physical examinations in entrapment neuropathy: sensory and motor functions compensation for the central nervous system in cases with peripheral nerve damage.

We performed electrophysiological studies and objective physical examinations in 60 patients with carpal tunnel syndrome and 21 patients with cubital tunnel syndrome. Compared with our normal data, the sensory nerve conduction velocity across the wrist was defined as abnormal in 97% of the carpal tunnel syndrome patients, the corresponding value of the amplitude of the sensory nerve action potential was 58% and the value of the two point discrimination test was 28% while the value of the Semmes-Weinstein monofilament test was defined as abnormal in 64% of the cases. In cubital tunnel syndrome patients, motor nerve conduction velocity across the elbow was defined as abnormal in 91%, the amplitude of the M-wave was 96%, manual muscle testing was 63% and their side pinch strength was defined as abnormal in 24% of the cases. The functions of recognition are preserved in the cases with moderate damage of peripheral nerve due to the cancellation of synaptic occlusion. Motor performance also compensated in the central nervous system. Therefore the sensitivity of the objective physical examination is less than that of electrophysiological study of peripheral nerve itself. For entrapment neuropathy electrophysiological findings are more sensitive than the objective physical examinations.

Expression of hnRNP B1 in four major histological types of lung cancers.

Heterogeneous nuclear ribonucleoprotein B1 is one of the nuclear pre-mRNA binding proteins involved in RNA metabolism. Recently, over-expression of B1 has been reported to be useful in the early detection of squamous cell carcinomas of the lung. To elucidate its significance in other histological types of lung cancers, we carried out a comparative study, four major types of lung cancers and normal lung tissues. 37 surgical specimens were examined using a B1-specific monoclonal antibody (2B2). Immunohistochemically, 2B2 demonstrated B1 protein in the nuclei not only of squamous cell carcinoma (10/10) but also of adenocarcinoma (17/18), small cell carcinoma (5/5) and large cell carcinoma (3/4). A lesser amount of B1 protein was also detected in normal cells. Quantitative immunoblotting revealed that B1 expression was markedly higher in cancer tissues than normal tissues and it varied among the four histological types. To establish the usefulness of B1, a threshold should be set for over-expression.

Interaction of hnRNP A2/B1 isoforms with telomeric ssDNA and the in vitro function.

Overexpression of heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1, especially of B1 has been reported as a useful marker to detect cancers in early stage, although the biological reason is not clear. A2/B1 proteins were previously reported to bind telomeric DNA repeats. Alternative splicing of A2/B1 gene produces abundant A2, less abundant B1, and testis-specific minor isoforms B0a and B0b. In this study, B1 and B0b that have the N-terminal 12 amino acid insertion were suggested to have higher affinities to telomeric single-stranded DNA (ssDNA) than A2 and B0a. Kinetic analyses using purified B1 and B0b indicated that they interact dynamically with a single array of telomeric repeats. Furthermore, functional assays demonstrated that B1 and B0b bind with telomeric repeats in a tandem fashion and protect them from a nuclease and promote telomerase activity. A2/B1 proteins, especially B1 and B0b, may function as telomeric ssDNA-binding proteins in cancer and reproductive cells.

Mutation analysis of mitotic checkpoint genes (hBUB1 and hBUBR1) and microsatellite instability in adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a neoplasm of T-lymphocytes, and human T-cell lymphotropic virus type-I (HTLV-I) is etiologically considered as the causative virus of ATLL. The karyotypes of ATLL are very complex in both number and structure, although no specific karyotype abnormalities have been identified. HTLV-I is thought to integrate its provirus into random sites in host chromosomal DNA and induces chromosomal instability. The BUB gene is a component of the mitotic checkpoint in budding yeast. Recently, human homologues of the BUB were identified and mutant alleles of hBUB1 and hBUBR1 were detected in two colorectal tumor cell lines, which showed microsatellite instability (MIN). In vitro, BUB proteins form a complex of monomers. These proteins interact with the human MAD1 gene product, a target of the HTLV-1 tax oncogene. We examined the role of checkpoint gene in the chromosomal abnormalities of ATLL by investigating mutations of hBUB1 and hBUBR1, and MIN of replication errors of BAX, insulin-like growth factor, and transforming growth factor beta type II. We analyzed ten cases with ATLL and eight B-cell lymphomas (five diffuse large cell lymphomas, three follicular lymphomas). Complex chromosomal abnormalities were detected in ATLL, while B-cell lymphomas showed only simple or minimal chromosomal abnormalities. Significant mutations/deletion of hBUB1 or hBUBR1 were detected in four of ten cases with ATLL, including two heterozygous point mutations, one homozygous point mutation, and one with a 47 bp deletion. In contrast, only one of eight B-cell lymphomas showed nonsense mutation of hBUBR1. None of the ATLL and B-cell lymphomas showed MIN. In the multistage process of leukemogenesis of ATLL, our findings indicate that mutations of mitotic checkpoint genes may play an important role in the induction of complex chromosomal abnormalities.

Closed-Wedge osteotomy for osteochondritis dissecans of the capitellum. A 7- to 12-year follow-up.

This article details a 7- to 12-year follow-up of seven young male baseball players with osteochondritis dissecans of the capitellum that we treated using closed-wedge osteotomy. This procedure was established by Yoshizu in 1986 for the treatment of "Little League elbow." The bone of the capitellum was revascularized and remodeled within 6 months in all seven patients. Six of the patients were able to return to full athletic activity and continued to play baseball. Radiographic assessment during the follow-up study revealed minimal osteoarthritic change and suggests that the treatment is useful for such an injury.

Intramedullary bone-cement fixation for proximal humeral fracture in elderly patients. A report of 5 cases.

We treated 5 proximal humeral fractures associated with advanced osteoporosis with conventional plate and screw fixation augmented by intramedullary bone cement. These osteosyntheses remained stable during a 1-year follow-up and the outcome was similar to that after fractures in younger patients without osteoporosis.

Matrix metalloproteinases and tissue inhibitors of metalloproteinases in joint fluid of the patients with loose artificial hip joints.

The pseudojoint cavity formed in patients undergoing total hip arthroplasty (THA) is later remodeled to synovial membrane-like tissue, which produces pseudosynovial fluid. This pseudosynovium also is an important source of matrix metalloproteinases (MMPs). As it is widely speculated that synovial fluid MMPs may contribute to local tissue degradation in rheumatoid arthritis (RA) and osteoarthritis (OA), we hypothesize that locally produced MMPs are found in the pseudosynovial fluid, via which they have access to the implant-host interface, and that if they retain their proteolytic potential, they might contribute to aseptic loosening. Enzyme-linked immunosorbent assay (ELISA), immunoblotting, and zymography were used to analyze MMPs and tissue inhibitors of metalloproteinases (TIMPs) in synovial fluid in aseptic loosening, which was compared to RA and OA. Pseudosynovial THA fluid was characterized using low levels of MMP-1 but moderate levels of MMP-13 and MT1-MMP (MMP-14). Due to the lack of an appropriate assay, MMP-13 and MT1-MMP were not similarly assessed, but the immunoblotting indicated that they were in the 56 kD intermediate proteolytically processed forms. The MMP-9 level was intermediate between RA and OA. MMP-2 was on a significant level, but there were no differences among study groups. The THA group also was characterized using relatively high levels of TIMP-1 and TIMP-2. Accordingly, MMP-9 and MMP-2 were found to occur in the 92 kD and 72 kD proenzyme form, respectively, with full activity retained in all study groups. The data suggest that proMMP-2-TIMP-2 and proMMP-9-TIMP-1 complexes are formed in the pseudosynovial fluid due to the excess of TIMPs over MMPs in aseptic loosening of THA. TIMP-complexed MMPs are resistant to MMP-mediated proteolytic activation, which may explain their latency and proenzyme zymogen form. Thus, formation of stabilizing proMMP-TIMP complexes enable transportation of proMMPs far from their original site of production. Due to motion-associated cyclic changes of the intra-articular pressure, fluid-phase MMPs stabilized by TIMPs might be absorbed to implant surfaces and interface tissues and help to dissect the implant/cement-to-bone interface in situ. Consequently, they may contribute to local proteolytic/tissue destructive events and aseptic loosening.

[An epidemic of aseptic meningitis caused by echoviruses in Fukuoka Prefecture during April 1997 to August 1998].

An epidemic of aseptic meningitis in Fukuoka Prefecture during April 1997 to August 1998 was studied to determine the serotype of viruses isolated in Fukuoka Prefecture. In Fukuoka Prefecture, bimodal peaks were seen in July and December 1997. Monthly changes of reported aseptic meningitis patients and period of virus isolation revealed that epidemics of the earlier part in 1997 was caused by echovirus 9 (E 9) and the latter part due to echovirus 30 (E 30). E 9 was isolated mainly in Chikugo Area from June to October 1997 but, E 30 was isolated all in areas of Fukuoka Prefecture. Isolation of E 30 continued after January 1998 in Fukuoka Prefecture. Isolation of echovirus 18 started in June 1998. The main serotypes of isolates are changing. The E 30 isolates are serotyped by neutralization with the aid of antiserum pools for enterovirus type differentiation, but serotyping was difficult with commercially available antiserum. The result of neutralization tests with standard serum and an immune albino rabbit serum prepared in our laboratory with the E 30 isolates indicated that the isolates in Fukuoka Prefecture was an antigenic variant.

Human PEX19: cDNA cloning by functional complementation, mutation analysis in a patient with Zellweger syndrome, and potential role in peroxisomal membrane assembly.

At least 11 complementation groups (CGs) have been identified for the peroxisome biogenesis disorders (PBDs) such as Zellweger syndrome, for which seven pathogenic genes have been elucidated. We have isolated a human PEX19 cDNA (HsPEX19) by functional complementation of peroxisome deficiency of a mutant Chinese hamster ovary cell line, ZP119, defective in import of both matrix and membrane proteins. This cDNA encodes a hydrophilic protein (Pex19p) comprising 299 amino acids, with a prenylation motif, CAAX box, at the C terminus. Farnesylated Pex19p is partly, if not all, anchored in the peroxisomal membrane, exposing its N-terminal part to the cytosol. A stable transformant of ZP119 with HsPEX19 was morphologically and biochemically restored for peroxisome biogenesis. HsPEX19 expression also restored peroxisomal protein import in fibroblasts from a patient (PBDJ-01) with Zellweger syndrome of CG-J. This patient (PBDJ-01) possessed a homozygous, inactivating mutation: a 1-base insertion, A764, in a codon for Met255, resulted in a frameshift, inducing a 24-aa sequence entirely distinct from normal Pex19p. These results demonstrate that PEX19 is the causative gene for CG-J PBD and suggest that the C-terminal part, including the CAAX homology box, is required for the biological function of Pex19p. Moreover, Pex19p is apparently involved at the initial stage in peroxisome membrane assembly, before the import of matrix protein.

Effects of the pH-controlled hemoglobin vesicles by CO2 gas.

The hemoglobin vesicle (HbV) is a red cell substitute encapsulating purified concentrated Hb in a phospholipid vesicle. In order to improve the oxygen carrying capability of HbV, the pH value of the Hb solution should be adjusted to 7.0 in the HbV preparation, and then the pH value should be adjusted to 7.4 where HbV functions as an oxygen carrier, because the maximum value of [Hb]/[Lipid] was obtained in which the pH of the Hb solution was 7.0, and the metHb formation rate was suppressed in the pH 7.4. Generally, the pH control of the inner aqueous phase of HbV is difficult by changing the pH in the outer phase. We could control the pH of the Hb solution from 7.4 to 7.0 by dissolving CO2 into the Hb solution, and after the preparation of HbV, the pH of HbV is changed to 7.4 by reducing the pressure. The resulting pH-controlled HbV by CO2 gas showed a high [Hb]/[Lipid] value of 1.7 with a low rate of metHb formation.

Subsidence of seizure induced by stereotactic radiation in a patient with hypothalamic hamartoma. Case report.

The authors report on a patient who exhibited intractable epilepsy due to an inaccessible hypothalamic hamartoma and subsequently underwent stereotactic radiosurgery. This 25-year-old man had a 24-year history of intractable gelastic and tonic-clonic seizures. Magnetic resonance (MR) imaging performed at examination as well as that performed 30 months earlier demonstrated a nonenhancing and nonprogressive spherical mass, approximately 10 mm in diameter, located on the patient's right side at the floor of the third ventricle. Focal radiation treatment performed with a gamma knife unit administered 36 Gy to the center and 18 Gy to the periphery of the lesion. This treatment resulted in an improvement in seizure control. Before the patient underwent radiosurgery, he suffered from three to six generalized seizures per month in spite of attentive compliance with an anticonvulsant medication regimen. After irradiation of the harmatoma, the frequency of the seizures transiently increased and then subsided 3 months posttreatment. The patient has been free of seizures for the last 21 months, with no neurological or endocrinological complications. Magnetic resonance imaging performed 12 months posttreatment demonstrated complete disappearance of the lesion.