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Biomedical subjects

M Osame

Publications and source records attributed to M Osame.

At least 271 records · Page 15Linked to original sources
PubMed1995

Cloning of rat lysosomal acid lipase cDNA and identification of the mutation in the rat model of Wolman's disease.

Lysosomal acid lipase (LAL) is a hydrolase essential for the intracellular degradation of cholesteryl esters and triglycerides. We previously reported a rat model of Wolman's disease (Wolman rat) that is deficient for LAL activity. In this study, we cloned rat LAL (RLAL) cDNA and investigated abnormal LAL gene expression in the Wolman rat. We cloned the RLAL gene from a cDNA library made from normal rat liver mRNA using the human LAL cDNA as a probe, subcloned the RLAL cDNA into pBlueScript vector, and sequenced it. Next, we constructed a cDNA library from a Wolman rat liver, and used the RLAL cDNA as a probe to isolate the Wolman RLAL cDNA for comparison. The normal RLAL cDNA contains 3150 bp including an 1194 bp open reading frame and three poly A signals at the 3' end. The deduced amino acid sequence contained 397 amino acids, showed 79.9% homology with human LAL, and had the same functional domains at the same sites as human LAL. Northern blot analysis revealed that the RLAL mRNA from normal rat was 3.2 kb in length, while the RLAL mRNA from Wolman rat was only 1.4 kb. Nucleotide sequence analysis showed that Wolman rat LAL cDNA had the same sequence as a RLAL cDNA from the 5'-untranslated region to nt 1101, followed by a 60 bp replacement from nt 1102 to nt 1161 with poly A signal and a 3' 1.8 kb deletion. The deduced amino acid sequence demonstrated the substitution of 367Ile to Asn, 368Pro to stop codon, and deletion of the C-terminal 29 amino acids. Genomic Southern blot analysis disclosed a large deletion at the 3' end of the gene. These results identify the molecular defect in the Wolman RLAL, and suggest that the C-terminus of RLAL is essential for the activity and/or stability of the enzyme.

Amino Acid Sequence↗
PubMed1995

[Lysosomal glycogen storage disease without acid maltase deficiency].

Lysosomal glycogen storage disease without acid maltase deficiency is characterized by the triad of clinical manifestations (hypertrophic cardiomyopathy), mental retardation, and mild myopathy), morphologic findings (glycogen storage, glycogenosomes, and autophagic vacuoles), and normal glycolytic enzyme activities. Though most of the patients suffering from the triad were males, family studies often revealed female patients with only cardiomyopathy. So far 27 cases have been reported. The cardiac involvement is progressive and fatal and as severe in females as in males. Many patients of both sexes die in their youth, unexpectedly, because of cardiac failure. The specific biochemical defect causing this disease remains unknown. From abnormal lectin staining patterns on the membrane and preclinical morphologic changes in biopsied skeletal muscle, membranous abnormality is suspected in this disease.

Cardiomyopathy, Hypertrophic↗
PubMed1995

[Multiple sclerosis viewed from the point of HTLV-I associated myelopathy].

Several interesting facts are observed in multiple sclerosis (MS) when it was viewed from the point of HTLV-I-associated myelopathy (HAM). The distribution of the two diseases is completely segregated each other and deeply related to races as shown in the figure. Both diseases have significant linkage to HLA; HAM being linked to HLA-DR1 with relative risk 3.8 whereas MS being linked to HLA-DR2 with relative risk 3.3. The clinical features of 363 HAM patients and 479 MS patients were compared using statistical multivariate analysis and patients with MS and HAM appeared in two distinct clusters. From the neuropathological point of view, MS is a disorder specifically related to demyelination and HAM is a disorder closely related to T-cell mediated inflammation. The biggest difference between HAM and MS is that the causative agent is known in HAM but not in MS. The studies on HAM will hopefully help to understand the pathomechanisms of MS.

Cluster Analysis↗
PubMed1994

Chronic inflammatory demyelinating polyneuropathy: histological and immunopathological studies on biopsied sural nerves.

We undertook histological and immunopathological studies on biopsied sural nerves from 9 patients with chronic inflammatory demyelinating polyneuropathy (CIDP). The diagnosis of CIDP was based on the research criteria proposed by the Ad Hoc Subcommittee of the American Academy of Neurology AIDS Task Force. The nerve pathology in these patients comprised macrophage-associated active demyelination and subsequent remyelination of various proportions. The presence of T cells in the endoneurium correlated with activity of demyelination. An analysis of T cell subsets demonstrated that the number of CD8-positive cells predominated over that of CD4-positive ones. Infiltration of B cells, and depositions of immunoglobulin and complement were not seen. These observations suggest that a T cell-mediated process is of pathogenic significance in CIDP. Furthermore, a double immunofluorescence staining revealed that most HLA-DR antigen-positive cells in the nerves in which active demyelination was seen coexpressed a macrophage-specific determinant. Conversely, HLA-DR-positive Schwann cells were found in the nerves in which remyelination was predominant. The expression of HLA-DR antigen on Schwann cells might not play a pathogenic role in the active demyelination in CIDP.

Adolescent↗
PubMed1994

Morphologic findings in biopsied skeletal muscle and cultured fibroblasts from a female patient with Danon's disease (lysosomal glycogen storage disease without acid maltase deficiency).

A family is reported in which three members were affected by cardiomyopathy. Two members died unexpectedly in their second decade. Only a 23-year-old male suffered from the triad of clinical manifestations (cardiomyopathy, mental retardation and vacuolar myopathy). Morphologic findings and biochemical studies of his biopsied skeletal muscle and cultured fibroblasts confirmed lysosomal glycogen storage disease with normal acid maltase that was first described by Danon et al. In this study we demonstrated early morphologic changes, storage of glycogen and abnormal membranous structures in disorganized myofibers in biopsied skeletal muscle from the elder sister, who only showed cardiomyopathy clinically. The aggregation of autophagosomes was prominent in cultured fibroblasts, with an increased glycogen content. The activity of acid alpha-glucosidase was higher than normal. This is a systemic storage disease with different expression in males and females.

Adolescent↗
PubMed1994

Cytosolic Ca2+ increase and cell damage in L6 rat myoblasts by HMG-CoA reductase inhibitors.

Acute rhabdomyolysis is caused by HMG-CoA reductase (HCR) inhibitors clinically and experimentally. To study the mechanism of muscle cell damage, we investigated the change in the cytosolic free Ca2+ concentration ([Ca2+]i) in L6 rat myoblasts stimulated with three kinds of HCR inhibitors: simvastatin, simvastatin-acid form and pravastatin. Simvastatin and simvastatin-acid form induced an increase in [Ca2+]i through two different pathways, namely, the Ca2+ release from intracellular stores and the Ca2+ influx from extracellular solution. They also caused cell puncture either in the presence or absence of extracellular Ca2+. Pravastatin induced little or no change in [Ca2+]i and no cell damage resulted. Simvastatin was 10-fold more potent than simvastatin-acid form. These results suggest that the mechanism of cell damage may relate to the [Ca2+]i elevation by these drugs and may be dependent on the lipophilicity of the inhibitors.

Animals↗
PubMed1994

Mechanisms of hyperpolarization induced by two cytokines, hTNF alpha and hIL-1 alpha in neurons of the mollusc, Onchidium.

The voltage and current responses induced by extracellular tumor necrosis factor (hTNF alpha) or interleukin-1 (hIL-1 alpha) on the Be-1 and Es-1 neurons of the Onchidium ganglia were examined. Pressure-ejected hTNF alpha or hIL-1 alpha produced an inhibitory, hyperpolarized effect in unclamped neurons. In the same neurons voltage-clamped at their resting potential levels, the same hTNF alpha or hIL-1 alpha elicited an outward current having a time course similar to that of the hyperpolarization, associated with a decreased membrane conductance. The hTNF alpha- or hIL-1 alpha-induced outward current did not reverse even at positive membrane potentials considerably above + 100 mV in the absence ouabain (a specific blocker of Na-pump). In the presence of ouabain, the hTNF alpha- or hIL-1 alpha-induced current was reduced over a wide range of membrane potential, so that the current reversed at about + 20 mV. Lowering the external Na+ concentration from 450 to 200 mM in the presence of ouabain, shifted the reversal potential from + 20 to 0 mV, to near the shift value of 20.8 mV predicted by the Nernst equation for a Na(+)-selective conductance. Neither an increase nor a decrease of extracellular K+, Cl- or Ca2+, however, significantly altered the current induced by hTNF alpha or hIL-1 alpha. These suggest that the hTNF alpha- or hIL-1 alpha-induced hyperpolarization or outward current response is mediated by two mechanisms, a decrease in Na+ conductance and activation of the Na-pump.

Animals↗
PubMed1994

Electrical myotonia of rabbit skeletal muscles by HMG-CoA reductase inhibitors.

HMG-CoA reductase (HCR) inhibitors are effective cholesterol-lowering agents in the treatment of hypercholesterolemia. Using intracellular microelectrodes, we studied the pathomechanism of myotonia experimentally induced in rabbits by HCR inhibitors, simvastatin, and pravastatin. The external intercostal muscle of rabbits showed some electrophysiologic characteristics of myotonia including repetitive firing after administration of simvastatin (50 mg/kg per day, for 4 weeks). The relative chloride conductance, though reduced in both, was more affected in simvastatin-administered muscles. In normal muscles perfused with a solution containing the inhibitors, both simvastatin and pravastatin produced membrane hyperexcitability with repetitive firing similar to that seen in simvastatin-administered rabbits. The minimum concentrations required to cause repetitive firing was 0.3 mg/L for simvastatin and 30 mg/L for pravastatin. These results indicate that HCR inhibitors induce some characteristics of myotonia by blocking the chloride channel in the muscle membrane.

Action Potentials↗
PubMed1994

Suppression of lymphocyte spontaneous proliferative response by proteolipid protein peptide in patients with HAM/TSP.

To understand the immune mechanism suggested in HTLV-I-associated myelopathy (HAM/TSP), we investigated T cell response to proteolipid protein (PLP). Because of high autologous proliferative response (APR) of peripheral blood mononuclear cells (PBMC) in culture, the lymphocyte proliferation assay was not useful in this disease. Unexpectedly, however, APR was profoundly (70-98%) suppressed in 6 of 9 cases when PLP peptide 105-124 was added in the culture. PLP peptide 85-104 or 145-159 also suppressed APR in a few cases. Time course study showed that the peptide-mediated suppression became apparent after day 4 in culture. The results can be interpreted as that suppressor cells recognizing the PLP peptides were present in the PBMC of HAM/TSP patients and suppressed the APR as the consequence of antigen specific response. This may indicate that a T cell response to certain PLP determinants is involved in the pathomechanism of HAM/TSP at least in part. Molecular mimicry between PLP and HTLV-I may account for the T cell sensitization to PLP in HAM/TSP.

Adult↗
PubMed1994

Treatment of cerebrotendinous xanthomatosis: effects of chenodeoxycholic acid, pravastatin, and combined use.

Treatments by oral administration of chenodeoxycholic acid (CDCA) alone, 3-hydroxy-3-methylglutaryl (HMG) CoA reductase inhibitor (pravastatin) alone, and combination of the two drugs were attempted for 7 patients with cerebrotendinous xanthomatosis (CTX). CDCA treatment at a dose of 300 mg/day reduced serum cholestanol (67.3% reduction), lathosterol (50.8%), campesterol (61.7%) and sitosterol (12.7%). However, the sera of the patients changed to be "atherogenic"; total cholesterol, triglyceride and low-density lipoprotein (LDL)-cholesterol were increased, while high-density lipoprotein (HDL)-cholesterol was decreased. Contrarily, pravastatin at a dose of 10 mg/day improved the sera of the patients to be markedly "anti-atherogenic", but the reductions of cholestanol (30.4%), lathosterol (44.0%), campesterol (22.9%) and sitosterol (9.6%) were inadequate. Combined treatment with CDCA and pravastatin showed good overlapping of the effects of each drug alone. The sera of the patients were apparently more "anti-atherogenic" than those after CDCA treatment. Serum cholestanol concentration was still 2.7 times higher than in controls, but the serum lathosterol level was within the normal range, indicating that the enhancement of overall cholesterol synthesis in the patients was sufficiently suppressed. Plant sterol levels were also within the normal range. The combination of CDCA and pravastatin was a good treatment for CTX, based on the improvement of serum lipoprotein metabolism, the suppression of cholesterol synthesis, and reductions of cholestanol and plant sterol levels. In all of 7 patients, the progression of disease was arrested, but dramatic effects on clinical manifestations, xanthoma, and electrophysiological findings could not be found after the treatment of these drugs.

Adult↗
PubMed1994

HTLV-I proviral DNA amount correlates with infiltrating CD4+ lymphocytes in the spinal cord from patients with HTLV-I-associated myelopathy.

A quantitative method utilizing polymerase chain reaction was employed to evaluate the amount of human T-cell leukemia virus type I (HTLV-I) proviral DNA in the affected spinal cords from patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Central nervous system (CNS) tissues were obtained at post-mortem from five patients with HAM/TSP, who vary in the duration of illness from 2.5-10 years, and one patient with adult T-cell leukemia (ATL), who had leukemic cell infiltration in the CNS. The presence of HTLV-I pX and pol sequences in the CNS tissues were demonstrated in all patients examined. In HAM/TSP, the proviral DNA quantified in the thoracic cord was 0.002-2 copies per 100 tissue cells, and that in the peripheral blood mononuclear cells (PBMC) was 2-8 copies per 100 PBMC. The proviral DNA amount in the thoracic cord of the patient with ATL was 0.4 copies per 100 tissue cells. An apparent propensity for the amount of integrated HTLV-I in the thoracic cord to decrease with the disease duration in patients with HAM/TSP was observed. The decline in HTLV-I proviral DNA amount in the thoracic cord lesions was paralleled with the alteration of proportion of CD4+ T lymphocytes in patients with HAM/TSP. These findings suggest that preferential virus reservoir may be infiltrating CD4+ T lymphocytes in the spinal cord lesions of patients with HAM/TSP, and HTLV-I infection in the CNS of patients is declining with the disease duration in spite of the chronic course of neurological manifestations at least in some patients with HAM/TSP.

Aged↗
PubMed1994

A spontaneous point mutation in the human T-cell leukemia virus type 1 pX gene leads to expression of a novel doubly spliced pX-mRNA that encodes a 25-kD, amino-terminal deleted rex protein.

Primary RNA transcripts of the human T-cell leukemia virus type 1 (HTLV-1) are processed into mature mRNA by a complex series of splicing events. In this paper, we report the finding of a novel doubly spliced pX mRNA in two out of eight HTLV-1-infected cell lines and in one out of 13 peripheral blood mononuclear cells from HTLV-1-infected individuals. The second splicing for this novel pX mRNA is different from that for the known doubly spliced pX mRNA. A novel acceptor site in this splicing was generated by a single point mutation (G to A) at nucleotide 7,337 of the pX gene. This mRNA contained a complete open reading frame that encodes an amino-terminal truncated p27rex protein with 189 amino acids. A new 25-kD protein was detected in the cell lines expressing the novel pX mRNA by an antibody against the carboxy-terminal peptide of p27rex and was termed p25rex. Although the function of p25rex is not clear, we clarified that p25rex is a cytoplasmic phosphoprotein and its function is different from the transcriptional regulator function of p27rex. The possibility that the mutated virus is replicable only in cells coinfected with the wild type HTLV-1 may explain why the incidence of the mutants observed here is low.

Amino Acid Sequence↗
PubMed1994

Cytokine expression in the spinal cord lesions in HTLV-I-associated myelopathy.

Immunocytochemical staining of spinal cords from five autopsied patients with HTLV-I-associated myelopathy/tropical spastic paraparesis was performed using a panel of monoclonal or polyclonal antibodies reactive with interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor (TNF)-alpha, interferon (IFN)-alpha, IFN-beta, IFN-gamma and transforming growth factor (TGF)-beta. In the spinal cords of patients with a shorter duration of illness, IL-1 beta, TNF-alpha, and IFN-gamma were expressed on perivascular infiltrating macrophages, astrocytes and microglia in active-chronic inflammatory lesions. In striking contrast, we rarely noted cytokine expression except for IFN-gamma in inactive-chronic lesions of patients with longer durations. In situ expression of these cytokines on microglia and astrocytes, in addition to infiltrating mononuclear cells, suggests that glial cells participate in the inflammatory process, especially in active lesions. In addition, the cytokine expression was gradually downregulated along with duration of illness.

Aged↗
PubMed1994

Apoptosis of T lymphocytes in the spinal cord lesions in HTLV-I-associated myelopathy: a possible mechanism to control viral infection in the central nervous system.

Immunocytochemical staining of spinal cords from five autopsied patients with HAM/TSP was performed using the monoclonal antibody TIA-1, a marker of cytotoxic T lymphocytes (CTL). Many TIA-1+, CD8+ cells are distributed in active inflammatory lesions. The number of TIA-1+ cells is related to the amount of HTLV-I proviral DNA in situ. The protein TIA-1 has been associated with the induction of apoptosis in target cells. In active inflammatory lesions, we found cells undergoing apoptosis, most of them identified as helper-inducer CD45RO T lymphocytes, which were consistent with in vivo cellular tropism of HTLV-I in patients with HAM/TSP. These findings suggest that CTL-induced apoptosis of T lymphocytes may be one of the possible mechanisms which eliminate HTLV-I-infected cells from the central nervous system. In addition, many T lymphocytes in the inflammatory lesions expressed bcl-2 oncoprotein, suggesting that infiltrated T lymphocytes may be resistant to apoptosis. Expression of bcl-2 oncoprotein may explain the longstanding inflammatory process in the central nervous system of HAM/TSP.

Antibodies, Monoclonal↗
PubMed1994

Paraneoplastic vasculitic neuropathy: immunohistochemical studies on a biopsied nerve and post-mortem examination.

We studied a patient with paraneoplastic vasculitic neuropathy (PVN) associated with a carcinoma of the common bile duct. Immunohistochemical analysis of the biopsied sural nerve showed that the cellular infiltrates in the vascular lesions were composed primarily of CD8-positive T lymphocytes and macrophages. Pathogenic significance of the T-cell-mediated immunological reaction was suggested. Post-mortem examination revealed the absence of systemic vasculitis, which may be a characteristic feature of PVN. The patient responded to immunosuppressive treatment. We discuss the efficacy and the risk of immunosuppressive therapy for PVN.

Adenocarcinoma↗
PubMed1994

Low levels of serum apolipoprotein A I and A II in senile dementia.

We studied the serum lipoprotein and apolipoprotein profiles in 44 patients with sporadic late-onset Alzheimer's dementia and 43 patients with vascular dementia. The levels of high-density lipoprotein (HDL) cholesterol were lower in both patient groups than in a control group. Apolipoprotein A I and A II levels have decreased in both the patient groups, especially in the vascular dementia group. The HDL-cholesterol levels correlated positively with the level of apolipoprotein A I, but not with the level of apolipoprotein A II. The ratios of apolipoprotein A I/A II have increased in both the patient groups. The apolipoprotein A II levels have disproportionally decreased in the patient groups. The serum apolipoprotein A II may involve the pathological process in the patients with senile dementia.

Aged↗
PubMed1994

A case of paternally inherited congenital myotonic dystrophy.

We report two sisters with congenital myotonic dystrophy (CDM) born to a normal mother and an affected father. The congenitally affected daughters had symptoms from birth. The age of onset of DM in the father was 39 years. Analysis of the CTG trinucleotide expansion in this family showed increase in the repeat length with increasing severity, with the smallest expansion in the grandfather and the largest expansion in the younger of the two CDM sisters. This family shows that exceptionally it is possible for CDM to be inherited paternally and refutes the hypothesis that CDM is exclusively of maternal origin. This contradicts several of the previous hypotheses concerning the mechanisms by which the CDM phenotype arises.

Adolescent↗