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Biomedical subjects

A Kawata

Publications and source records attributed to A Kawata.

At least 19 recordsLinked to original sources
PubMed2006

Ligand-of-Numb protein X is an endocytic scaffold for junctional adhesion molecule 4.

Junctional adhesion molecule 4 (JAM4) is a cell adhesion molecule that interacts with a tight junction protein, membrane-associated guanylate kinase inverted 1 (MAGI-1). Our previous studies suggest that JAM4 is implicated in the regulation of paracellular permeability and the signalings of hepatocyte growth factor. In this study, we performed yeast two-hybrid screening to search for an unidentified JAM4-binding protein and obtained one isoform of Ligand-of-Numb protein X1 (LNX1), LNXp70, that is an interactor of Numb. Ligand-of-Numb protein X1 is expressed in kidney glomeruli and intestinal epithelial cells, where JAM4 is also detected. Immunoprecipitation from kidney lysates supports the in vivo interaction of proteins. Biochemical studies reveal that JAM4 directly binds the second PDZ domain of LNX1 through its carboxyl terminus. Junctional adhesion molecule 4, LNX1 and Numb form a tripartite complex in vitro and are partially colocalized in heterologous cells. Ligand-of-Numb protein X1 facilitates endocytosis of JAM4 and is involved in transforming growth factor beta -induced redistribution of JAM4 in mammary epithelial cells. Experiments using dominant-negative constructs and RNA interference insure that Numb is necessary for the LNX1-mediated endocytosis of JAM4. All these findings indicate that LNX1 provides an endocytic scaffold for JAM4 that is implicated in the reorganization of cell junctions.

Animals↗
PubMed2004

Hereditary paroxysmal ataxia with mental retardation: a clinicopathological study in relation to episodic ataxia type 2.

A case of hereditary acetazolamide-responsive paroxysmal ataxia with mild mental retardation in an autopsied Japanese man is described. His ataxic attacks had occurred for approximately 65 years since the age of 6. One of his daughters had severe mental retardation and epilepsy, and the other had paroxysmal ataxic attacks and mild mental retardation. Analysis of the subject's CACNA1A gene and that in his daughter revealed neither mutations nor CAG expansion. Neuropathologically, cortical degeneration consisting of the marked loss of Purkinje and granule cells was found exclusively in the cerebellar vermis. This was consistent with findings at autopsy for cases reported as spinocerebellar ataxia 6. In addition, there were minor anomalies, such as hypoplastic cerebellum and brainstem, heterotopic Purkinje cells, and cortical microdysgenesis of the temporal lobe. It is considered that the cerebellar cortical degeneration and the minor malformations found in the brain are closely related to one another, rather than having occurred independently.

Adult↗
PubMed2001

Experimental allergic myositis in SJL/J mouse. Reappraisal of immune reaction based on changes after single immunization.

SJL/J mice have been subjected to immunization with wide varieties of antigens to produce models of autoimmune disorders including experimental myositis. They also have a defect in dysferlin gene and spontaneously develop muscle fiber degeneration, a condition akin to limb-girdle type muscular dystrophy and Miyoshi myopathy. To know whether muscle inflammation of SJL mice after immunization with muscle fractions really represents immune-mediated myositis or no more than an epiphenomenon of muscle degeneration due to dysferlin defect, we studied immunological parameters after immunization with rabbit myosin B fraction. Initial infiltration of macrophages and CD4+ lymphocytes on day 11 was followed by increase in number of CD8+ cells. Such increase was not observed in the nontreated and adjuvant controls. Some infiltrating cells were interferon gamma (IFN-gamma) positive. Furthermore, increased expression of the signal transducers and activator of transcription 1 (STAT-1) and interferon regulatory factor 1 (IRF-1) mRNA was shown in the first 2 weeks. These results indicate Th1 system activity in the muscle, rather than simple dysferlin deficiency, particularly 1-3 weeks after immunization. Thus it is concluded that an immune-mediated myositis is taking place at this stage. This model can be helpful in understanding pathomechanisms involved in the early stage of human myositides. It has also important implications concerning immune reactions associated with transplantation or gene therapy for muscular dystrophies.

Animals↗
PubMed2001

Cytotoxic T cell activity against the peptide, AYRARALEL, from Yo protein of patients with the HLA A24 or B27 supertype and paraneoplastic cerebellar degeneration.

OBJECTIVE: To determine a peptide that reacts with cytotoxic T cells (CTL) of patients with paraneoplastic cerebellar degeneration and anti-Yo antibodies with either HLA A24 or B27 supertype. METHOD: We studied CTL activity of four patients, three were HLA A24-positive and one did not have HLA A24 but had B27 supertype. After an incubation of mononuclear cells with or without peptide and IL-2, CD8-rich fraction was prepared by treatment with Magnetic Cell Sorting system (MACS) twice. CTL activity was calculated by 51Cr release from transfectant, C1RA*2402 as target cells. The peptide-binding assay was examined by flow cytometry. RESULTS: Two of three HLA A 24-positive patients demonstrated CTL activity against the Yo peptide, AYRARALEL. CTL activity was found to be 19.5% and 11.7% at the effector/target (E/T) ratio of 23:1 and 11:1, respectively. A patient who did not have HLA A24 but had A2 and B27 supertype possessed a CTL activity of 19.4% with 15:1 as E/T ratio. The peptide could bind to HLA A*2402 molecules but not to A*0201. CONCLUSIONS: We showed CTL activity in two of three Japanese patients with HLA A24 by using HLA A*2402 transfectant cells as the target. In addition, we identified the first Japanese patient who had B27 supertype, and suggested that the same peptide, AYRARALEL, could be recognized by CTL in this patient.

Autoantigens↗
PubMed2001

Cause-specific mortality risk among male alcoholics residing in the Osaka metropolitan area.

We evaluated the mortality risk among 306 male alcoholics living in Osaka, Japan, at the time of initial diagnosis between 1972 and 1983, with regard to the cause of death, length of time from diagnosis, and participation in an alcohol abstinence self-help group. By the closing date on 1 March 1992, 110 of the 306 alcoholics had died, yielding an observed-to-expected (O/E) ratio of 4.5 [95% confidence interval (CI) = 3.7-5.4]. The alcoholics had significantly elevated mortality risks from all malignant neoplasms (O/E = 2.1, 95%CI = 1.2-3.3), esophageal cancer (O/E = 8.4, 95%CI = 1.7-24.5), diseases of the circulatory system (O/E = 4.4, 95%CI = 3.0-6.2), liver cirrhosis (O/E = 15.9, 95%CI = 10.2-23.6), diseases of the genitourinary system (O/E = 6.3, 95%CI = 1.3-18.5), and external death (O/E = 10.3, 95%CI = 6.3-15.8). The mortality risk from all causes still remained significantly high beyond the tenth year following initial diagnosis (O/E = 2.6, 95%CI = 1.0-6.2). The mortality risks from liver cirrhosis and external death (such as suicide) were highest within the first year following diagnosis, and were still high beyond the tenth year. A significantly high mortality risk from diseases of the circulatory system was observed between the first and ninth years, and the mortality risk from all malignant neoplasms was significantly elevated beyond 10 years following diagnosis. Alcoholics who did not join a self-help group soon after the initial institutional treatment had different cause-specific and time-specific mortality risks from those who did join a self-help group. These findings show the importance of long-term clinical follow-up of male alcoholics, taking into consideration the cause-specific mortality.

Adult↗
PubMed2001

Long-term outcome in 306 males with alcoholism.

The subjects of this study were 306 male alcoholics who lived in Osaka, Japan, and who were initially diagnosed with alcoholism at a psychiatric institution between 1972 and 1983. Follow-up studies were done on three occasions: 1 March 1985 (Time 1), 1 November 1988 (Time 2) and 1 March 1992 (Time 3). We followed up 232 (75.8%) of the 306 male alcoholics. By the end of the study period 110 (35.9%) of the subjects were deceased. Regarding cross-sectional sobriety status, from Time 1 to Time 3 the complete abstinence rate changed from 16.0 to 18.6%, excessive drinking rate was from 13.1 to 9.8%, and controlled drinking rate was from 6.9 to 9.8%. The longitudinal sobriety status of 122 living patients during the 5 years before the close of this study were: rate of stable abstinence, 28.7%; unstable abstinence, 21.3%; controlled drinking, 12.3%; and relapse 37.7%. Such variables as being without public assistance at the time of the initial diagnosis of alcoholism and attending a self-help group soon after the initial treatment were associated with stable abstinence. Age (20-39 years) and receiving outpatient treatment at the time of the initial treatment also emerged as predictors of survival. However, those variables, except attending a self-help group soon after the initial treatment, might merely indicate severity of alcoholism. For improving treatment results, it may be most important to provide a treatment environment within the residential area so that alcoholics may receive treatment at an early stage of alcoholism and attend a self-help group.

Adult↗
PubMed2001

Masseter inhibitory reflex in amyotrophic lateral sclerosis.

OBJECTIVES: To elucidate underlying abnormalities of the masseter motor system in amyotrophic lateral sclerosis (ALS). METHODS: We recorded biphasic EMG suppressions of the masseter muscle (silent or inhibitory periods 1 and 2) after electrical stimulation of the mental nerve during maximum clenching of the teeth in 16 ALS patients and 15 healthy control subjects. We also examined the recovery cycle of the silent periods by delivering paired stimuli with an interstimulus interval of 250 ms. RESULTS: Silent period 1 in the patients was not significantly different from that in control subjects, whereas silent period 2 (as measured by its area on the graph) was increased in the patients, especially with exaggerated jaw jerk. Only two patients showed absence of silent period 2. The recovery cycle of silent period 2 in the subgroup of patients with exaggerated jaw jerk was significantly lower than the control value. CONCLUSIONS: The abnormalities of the masseter inhibitory reflex in ALS could be ascribable to involvement of the corticobulbar or corticoreticular tract projecting to the inhibitory interneurons mediating silent period 2.

Adult↗
PubMed2001

Matrix metalloproteinase-2 in dentin matrix mineralization.

In the serum-free culture medium of bovine odontoblasts we detected active gelatinolytic metalloproteinases, matrix metalloproteinase (MMP)-2 and MMP-9 (gelatinases A and B). The activity of MMP-2, in particular, appeared suddenly around day 21 in the culture, coinciding with the development of odontoblastic cell processes and the loss of alkaline phosphatase. Reverse transcriptase-polymerase chain reaction analysis of these odontoblasts demonstrated that messages of MMP-2 but not MMP-9 increased significantly between day 15 and day 21. The in vitro observation indicates that medium conditioned by these odontoblasts and containing significant amounts of MMP-2 degrades not only the collagenous substrates but also purified dentin phosphophoryn as well. We have also observed that dephosphorylated dentin phosphoprotein becomes a better substrate for casein kinase II after limited proteolysis with MMP-2. These results support our working hypothesis that MMP-2-mediated proteolytic processing is an important step in accelerating the process of dentin matrix maturation, which includes phosphorylation and subsequent mineralization. As has been suggested previously, extracellular phosphorylation of matrix proteins is an important step in biomineralization both in bone and in dentin (Mikuni-Takagaki et al., J Bone Miner Res 1995;10:231-42; Zhu et al., Biochem J 1997; 323:637-43). Our present histochemical analysis in MMP-2 knockout mice confirms the concept with the delayed formation of mineralized tissues, dentin, and bone.

Alkaline Phosphatase↗
PubMed2001

Effects of amino acids on the amidation of polyaromatic carboxylic acids by Bacillus cereus.

The soil bacterium Bacillus cereus Tim-r01 efficiently transformed polyaromatic carboxylic acids (PACA) such as 4-biphenylcarboxylic acid (4-BPCA), 4-biphenylacetic acid, and 4-phenoxybenzoic acid into their corresponding amides. The amidation activity was expressed at 37 degrees C (pH 7-8) in the presence of grown cells in nutrients under an aerobic atmosphere. Other strains of B. cereus, IFO 3001 and IAM 1229, also gave the amide from 4-BPCA. In phosphate-buffered saline (PBS), the addition of normal amino acids was essential, while sulfur-containing amino acids such as methionine and cysteine drastically inhibited the amidation. Tracer experiments using N-15-isoleucine and N-15-alanine showed that the nitrogen atom of the amide came from an amino group of amino acids but not from ammonia or alkylamines.

Amides↗
PubMed2001

[Clinical features of autosomal dominant spinocerebellar ataxias genetically unclassified into any known triplet-repeat diseases].

To clarify the clinical features of genetically unclassified autosomal dominant spinocerebellar ataxias (AD-SCAs) treated in our hospital, we retrospectively analyzed the clinical findings of patients who could not be molecularly classified into SCA types 1 through 3, 6 through 8, 12 and dentato-rubro-pallido-luysian atrophy (DRPLA). The clinical findings of 19 patients from 15 different families which form 14 percent of all patients with different types of AD-SCAs (136 patients, 105 families) were collected. Based on these, 17 patients from 13 families showed late-onset (mean age at onset: 46 years old) and slowly progressive truncal and limb ataxias of cerebellar origin. Some of them showed gaze-evoked nystagmus, increased deep reflexes without Babinski sign, tremor, mildly decreased vibration sense and mild rectourinary disturbances. All but one were still ambulatory after 15 years of their mean disease duration. An earlier disease onset in successive generations was observed in 8 families. Brain MRIs revealed cerebellar atrophy predominantly in the anterior vermis in all the patients and mild brainstem atrophy in only 3 patients. Although the clinical phenotype manifested by most of the genetically unclassified AD-SCAs is similar to that of SCA6, whether the phenotype is caused by expansion of triplet repeats or some mutations in a single gene or different mutations in various genes is still unclarified.

Adult↗
PubMed2000

Aberrant splicing of human Cu/Zn superoxide dismutase (SOD1) RNA transcripts.

Two abnormal SOD1 mRNAs, exon 2-skipping and exon 2 and 3-skipping species, were identified from occipital brain tissue of sporadic amyotrophic lateral sclerosis (ALS) patients carrying no mutations in the SOD1 gene. Both transcripts were ubiquitously expressed in non-neuronal as well as neuronal tissues from a subject without neurological diseases. The expression pattern did not show disease specificity or lesional selectivity associated with ALS. Transient expression studies revealed weak expression of the proteins derived from the exon 2-skipping SOD1 cDNA in a cell-free translation system but not in cells. The putative abnormal SOD1 protein may accumulate and exert toxic effects on motor neurons in ALS when the proteolytic system is disturbed by aging or some causal factors.

Adolescent↗
PubMed2000

Autonomic failure in ALS with a novel SOD1 gene mutation.

The authors report a patient with ALS and a novel SOD1 gene mutation who was in the totally locked-in state and developed autonomic failure followed by sudden cardiac arrest. A neuropathologic study showed widespread multisystem degeneration, including involvement of the autonomic nuclei in the medulla and spinal cord. SOD1 gene analysis detected a missense mutation of V118L in exon 4. These findings show notable phenotypic heterogeneity for SOD1-associated ALS.

Adult↗
PubMed1999

[A family of SCA1 with pigmentary macular dystrophy].

Pigmentary macular dystrophy (PMD) was detected in a 57-year-old Japanese man with SCA1, five years after the onset of ataxia. Family history revealed 7 other ataxic members in three generations. Among them, only his younger brother, who had already died, had developed central scotoma with normal peripheral fields, 15 years after the ataxia had appeared. None of the other family members, with or without ataxia, had visual disturbances. The numbers of CAG repeats in the patient's SCA1 gene were 27 and 47, the latter of which was within pathological range and belonged to mild to moderate CAG expansion in previously reported cases. The PMD seen in our patient could be one of the clinical features associated with SCA1, since patients with SCA1 often show various ocular changes. Although genetic analysis ruled out SCA7 in this patient, the phenotypic resemblance of this patient to SCA7 may reflect the necessity in the future, for genetic differentiation between SCA1 and SCA7 in patients with autosomal dominant cerebellar ataxia and PMD.

Adult↗
PubMed1998

Mechanotransduction in stretched osteocytes--temporal expression of immediate early and other genes.

Osteocytes, dendritic bone cells, transduce signals of mechanical loading that results in bone formation. We have reported in stretched primary osteocytes that the cAMP level, IGF-I and osteocalcin protein levels were elevated (Endocrinology 137:2028, 1996). Here we report that stretching induces the expression of immediate early genes, c-fos, and COX-2; inducive cyclooxygenase gene. Compared to c-fos, COX-2 as well as IGF-I and osteocalcin mRNA appeared in a biphasic manner; second peaks at 8 (COX-2) or 24 hrs (IGF-I and osteocalcin) later. Furthermore, these second peaks are abolished by including NS398, a specific inhibitor of the inducive cyclooxygenase, during the 3-hr stretching. A sequence that the calcium influx activates PkA which, in turn, activates c-fos and COX-2 transcription resulting in the production of proteins such as IGF-I and osteocalcin. A long-lasting effect of mechanical loading in vivo can be explained from the secondary anabolic reaction we observed through the upregulated COX-2 mRNA.

Animals↗
PubMed1997

Prominent sensory and autonomic disturbances in familial amyotrophic lateral sclerosis with a Gly93Ser mutation in the SOD1 gene.

A missense mutation (Gly93-->Ser) was identified in exon 4 of the Cu/Zn superoxide dismutase (SOD1) gene of a 48-year-old Japanese man with familial amyotrophic lateral sclerosis (FALS). The SOD1 activities in the fibroblasts and in a lysate of erythrocytes of the patient did not differ from those of healthy controls. The clinical characteristics of the patient were fairly slow progression of the illness, prominent sensory impairment, urinary disturbance and blood pressure fluctuation due to sympathetic hyperactivity. The severe sensory and autonomic disturbances, association of which with FALS has not been previously reported, may represent specific clinical features associated with the Gly93Ser mutation or may indicate the variability of clinical findings even in patients with the same mutation.

Amyotrophic Lateral Sclerosis↗
PubMed1997

Development of a severe combined immunodeficiency (SCID) mouse model consisting of highly disseminated human B-cell leukemia/lymphoma, cure of the tumors by systemic administration of immunotoxin, and development/application of a clonotype-specific polymerase chain reaction-based assay.

A new severe combined immunodeficiency (SCID) mouse model consisting of highly disseminated human B-cell leukemia/lymphoma was developed by i.v. inoculation of BALL-1a, an in vivo adapted malignant B-cell line. A 100% transplantability was achieved in nonpreconditioned SCID mice using various BALL-1a doses between 2.5 x 10(4) and 6 x 10(6) cells. Hind-leg paralysis preceded the death of the mice. Utility of the developed tumor model for the therapeutic studies was investigated by i.v. administration of an anti-B-cell monoclonal antibody SN7 (IgG1) and its conjugate with deglycosylated ricin A chain (dgRA). The therapy was initiated 2, 4, or 6 days after tumor inoculation using 4 x 24 microg of SN7-dgRA or 4 x 20 microg of SN7; the total dose (96 microg) of SN7-dgRA corresponded to 14% of the LD50 dose. SN7-dgRA showed a strong antitumor efficacy in all groups of treated mice. All of the day-2 group mice (n = 7) and six (66.7%) of the day-4 group mice (n = 9) survived healthily for as long as followed (240 days), whereas four (57.1%) of the day-6 group mice (n = 7) survived healthily for as long as followed (200 days). Unconjugated SN7 showed a significant antitumor efficacy but was less effective than SN7-dgRA. A PCR-based assay specific for the clonogenic BALL-1a tumor was developed and applied to determine tumors in various organs of BALL-1a-bearing SCID mice. The assay was highly sensitive in screening for trace quantities of residual tumors in various organs of SCID mice, and it could detect 1 malignant cell/2.5 x 10(5) tissue cells. The PCR-based assay was shown to be much more powerful than the conventional histological analysis in detecting residual tumors. Furthermore, we could estimate quantities of the detected tumors by the PCR-based assay. It is remarkable to find that all examined organs of some of the SN7-dgRA-treated mice were tumor-free as determined by the clonotype-specific PCR-based assay. The present results show the usefulness of the newly developed SCID mouse model, SN7-dgRA, and the clonotype-specific PCR-based molecular assay for the study of therapy of human B-cell leukemia/lymphoma.

Animals↗
PubMed1997

Adult-onset type II citrullinemia: clinical pictures before and after liver transplantation.

In a 25-year-old man with adult-onset type II citrullinemia, liver transplantation resulted in elimination of hyperammonemia and amino acid abnormalities associated with the disease. Postoperatively, a high intensity area in the right cingulate gyrus on a T2-weighted brain magnetic resonance imaging (MRI) also disappeared, suggesting that it reflected an early reversible lesion due to the hyperammonemia. Moreover, the serum level of pancreatic secretory trypsin inhibitor (PSTI), which had been elevated, was normalized. Since the levels of PSTI mRNA and PSTI have been reported to be increased in the livers of type II citrullinemia patients, measurement of serum PSTI levels could aid in the diagnosis of this disease.

Adult↗