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M Aikawa

Publications and source records attributed to M Aikawa.

At least 127 records · Page 7Linked to original sources
PubMed1995

Glomerular expression of smooth-muscle myosin heavy-chain isoforms in aminonucleoside nephrosis in rats.

1. We investigated the glomerular expression of three types of myosin heavy-chain isoforms, including S-myosin heavy-chain 40 (SM1), S-myosin heavy-chain 29 (SM2) and FS-myosin heavy-chain 34 (SMemb) in puromycin aminonucleoside nephrosis. 2. There was little change in SM1 and SM2 mRNA levels throughout the experiment. In contrast, glomerular SMemb mRNA increased on days 2 and 4 (before and soon after the onset of proteinuria, respectively), but declined on day 8 (the peak of proteinuria). 3. Histological myosin heavy-chain expression was examined using three antibodies against SM1, SM2 and SMemb. Immunohistochemically, SM1 and SM2 were absent in the glomeruli associated with puromycin aminonucleoside nephrosis until day 20. The SMemb isoform was barely detectable in normal glomeruli, but substantial amounts of SMemb were demonstrated in the glomeruli of rats with puromycin aminonucleoside nephrosis. In the puromycin aminonucleoside-treated rats, the number of SMemb-positive glomerular cells increased on days 2 and 4. 4. We examined whether levels of alpha-smooth-muscle actin or proliferating cell nuclear antigen correlated with myosin heavy-chain levels in the glomeruli of rats with puromycin aminonucleoside nephrosis. None of the cellular components in the glomeruli was positive for either alpha-smooth-muscle actin or proliferating cell nuclear antigen in puromycin aminonucleoside nephrosis. 5. Administration of methylprednisolone to puromycin aminonucleoside-treated rats resulted in the rapid disappearance of proteinuria. However, methylprednisolone did not affect SMemb mRNA or immunostaining in a glomeruli of rats with puromycin aminonucleoside nephrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Plasmodium falciparum protein associated with the invasion junction contains a conserved oxidoreductase domain.

The merozoite cap protein-1 (MCP-1) of Plasmodium falciparum follows the distribution of the moving junction during invasion of erythrocytes. We have cloned the gene encoding this protein from a cDNA library using a monoclonal antibody. The protein lacks a signal sequence and has no predicted transmembrane domains; none of the antisera reacts with the surfaces of intact merozoites, indicating that the cap distribution is submembranous. MCP-1 is divided into three domains. The N-terminal domain includes a 52-amino-acid region that is highly conserved in a large family of bacterial and eukaryotic proteins. Based on the known functions of two proteins of this family and the pattern of amino acid conservation, it is predicted that this domain may possess oxido-reductase activity, since the active cysteine residue of this domain is invariant in all proteins of the family. The other two domains of MCP-1 are not found in any other members of this protein family and may reflect the specific function of MCP-1 in invasion. The middle domain is negatively charged and enriched in glutamate; the C-terminal domain is positively charged and enriched in lysine. By virtue of its positive charge, the C-terminal domain resembles domains in some cytoskeleton-associated proteins and may mediate the interaction of MCP-1 with cytoskeleton in Plasmodium.

Amino Acid Sequence↗
PubMed1995

Adhesion of Plasmodium falciparum-infected erythrocytes to human cells and secretion of cytokines (IL-1-beta, IL-1RA, IL-6, IL-8, IL-10, TGF beta, TNF alpha, G-CSF, GM-CSF.

The scientific interest in the physical interaction of Plasmodium falciparum-infected erythrocytes with host cells stems from the suggestion that excessive binding in the microvasculature leads to severe malaria. The authors studied, therefore, two parasites for their ability to adhere to normal human cells and to induce cytokine production, one parasite lacking a binding capacity (DD2) and one which adhered to CD36+ transfected CHO cells (MCAMP). The MCAMP parasites readily bound to platelets and erythrocytes and to monocytes, polymorphonuclear granulocytes and EBV-transformed B cells as seen by light and electron microscopy. Platelets were frequently attached in large numbers to the infected erythrocyte surface and groups of infected erythrocytes were sometimes held together by several platelets. Nine out of 17 cytokines tested were found to be secreted into the culture supernatants after 35 h of co-cultures containing monocytes or unfractionated peripheral blood mononuclear cells (PBMC) and parasites (IL-1RA, IL-6, IL-8, IL-10, TGF beta, TNF alpha, G-CSF, IL-1-beta, and GM-CSF). Three additional cytokines were also present in low levels (< 200 pg/ml, IL-2, IL-4, IFN gamma) in the culture supernatants after incubation of the cells for 4 days. TNF alpha, IL-RA, and IL-8 were secreted from polymorphonuclear granulocytes, LGLs and T cells. Platelets and, to a lesser degree, monocytes and T cells secreted large amounts of TGF beta (10-30 ng/ml). Cytokines may participate in the pathogenesis but also the suppression of immune responses seen during acute malarial infections.

Animals↗
PubMed1995

A correlation between sequestered parasitized erythrocytes in subcutaneous tissue and cerebral malaria.

Sequestered parasitized erythrocytes were found in microvessels of subcutaneous tissues in a comatose patient with cerebral malaria even though the blood smears were negative after quinine treatment. This situation reflects the continued presence of sequestered parasites in the brain and suggests that negative parasitemia in peripheral blood does not necessarily mean the end point of malarial treatment has been reached. Our findings suggest that biopsy of subcutaneous tissue from severe malaria patients may be useful for determining the severity and prognosis of malaria patients.

Adult↗
PubMed1995

Smooth muscle phenotypes in developing and atherosclerotic human arteries demonstrated by myosin expression.

Smooth muscle myosin heavy chains (MHC) exist in multiple isoforms. Rabbit smooth muscle contain at least three types of MHC isoforms; SM1 (204 kDa), SM2 (200 kDa) and SMemb (200 kDa). SM1 and SM2 are specific to smooth muscle, but SMemb is a nonmuscle-type MHC abundantly expressed in the embryonic aorta and in activated mesenchymal cells. We previously reported that these three MHC isoforms are differentially expressed in rabbit during normal vascular development and in experimental arteriosclerosis and demonstrated that MHC isoforms are excellent markers for smooth muscle phenotype. In order to clarify the clinical significance of MHC isoforms, this article will focus on the expression of smooth muscle MHC isoforms in normally developing and atherosclerotic human arteries, especially in coronary arteries. We recently isolated and characterized three cDNA clones encoding human SM1, SM2, and SMemb. The expression of SM2 mRNA in the human fetal aorta was significantly lower as compared to SM1 mRNA but the ratio of SM2- to SM1-mRNA was increased after birth. SMemb mRNA in the aorta was decreased after birth. Immunohistologically, SM1 was constitutively positive from the fetal stage to adulthood in the apparently normal media of the aorta and coronary arteries, whereas SM2 was not detected in fetal arteries of early gestational stage. SM2 was recognized in well-differentiated smooth muscle after perinatal stage. In the human aorta or coronary arteries, unlike in rabbit, SMemb was detected even in the adult. Mild diffuse intimal thickening in the major coronary arteries of the young was found to be composed of smooth muscle cells, reacting equally to three antibodies for MHC isoforms. In thickened but non-atheromatous intima, the expression of well-differentiated smooth muscle-specific MHC (SM2) was reduced, especially in the deeper layer. With progression of atherosclerosis, intimal smooth muscle diminished the expression of not only SM2 but also SM1, whereas alpha-smooth muscle actin was well preserved. We conclude from these results that smooth muscle MHC isoforms are important molecular markers for studying human vascular smooth muscle cell differentiation as well as the cellular mechanisms of atherosclerosis.

Amino Acid Sequence↗
PubMed1995

[Smooth muscle myosin heavy chain expression in the arterial wall; a new viewpoint for vascular pathology].

Smooth muscle is an important component of the vessel wall. Smooth muscle cell undergoes phenotypic modulation during development of vascular lesions, such as atherosclerosis and restenosis following percutaneous transluminal coronary angioplasty (PTCA). In order to understand the mechanism of vascular remodeling, it is important to identify the smooth muscle cell in the vascular lesion and identify its phenotype by using molecular markers specific to the smooth muscle cell. Three types of myosin heavy chain (MHC) isoforms (SM1, SM2 and SMemb) expressed in smooth muscles are suitable for this purpose. In this study we first demonstrated that the expression of smooth muscle specific MHCs, such as SM1 and SM2, is reduced in human coronary arteries after the fifth decade. On the other hand, rapidly proliferating smooth muscles in the restenotic lesion express abundant SMemb but less amount of SM2. These observations indicate that deranged vascular smooth muscle differentiation is involved the development of vascular lesion. We furthermore demonstrated that smooth muscle-specific MHC is released into serum from the arterial wall following vascular damage as in dissecting aneurysm. Circulating smooth muscle MHC level was elevated 5-10 times above normal at 24 hours after aortic dissection as determined using a sensitive ELISA. We conclude from these results that smooth muscle MHC isoforms are important molecular markers for vascular pathology as well as for biochemical diagnosis of vascular injuries.

Aortic Dissection↗
PubMed1994

Merozoite surface protein-3: a malaria protein inducing antibodies that promote Plasmodium falciparum killing by cooperation with blood monocytes.

We have previously found that the acquired protection against malaria implicates a mechanism of defense that relies on the cooperation between cytophilic antibodies and monocytes. Accordingly, an assay of antibody-dependent cellular inhibition (ADCI) of parasite growth was used as a means of selecting for molecules capable of inducing protective immunity to malaria. This allowed us to identify in the sera of clinically protected subjects an antibody specificity that promotes parasite killing mediated by monocytes. This antibody is directed to a novel merozoite surface protein (MSP-3) of a molecular mass of 48 kD. Purified IgG from protected subjects are effective in ADCI and those directed against MSP-3 are predominantly cytophilic. In contrast, in nonprotected individuals, whose antibodies are not effective in ADCI, anti-MSP-3 antibodies are mostly noncytophilic. A region in MSP-3 targetted by antibodies effective in the ADCI assay was identified and its sequence was determined; it contains an epitope not defined by a repetitive structure and does not appear to be polymorphic. Antibodies raised in mice against a peptide containing this epitope, as well as human antibodies immunopurified on this peptide, elicit a strong inhibition of Plasmodium falciparum growth in ADCI assay, whereas control antibodies, directed to peptides from other molecules, do not. The correlation between isotypes of antibodies produced against the 48-kD epitopes, clinical protection, and the ability of specific anti-MSP-3 antibodies to block the parasite schizogony in the ADCI assay suggests that this molecule is involved in eliciting protective mechanisms.

Amino Acid Sequence↗
PubMed1994

A nonhuman primate model for human cerebral malaria: rhesus monkeys experimentally infected with Plasmodium fragile.

We studied the brains of rhesus monkeys infected with the primate malaria parasite Plasmodium fragile. Electron microscopy showed that, in these animals, erythrocytes infected with P. fragile undergo sequestration and that parasitized red blood cells adhere to endothelial cells in the cerebral microvessels by means of knobs. Cerebral microvessels with sequestered parasitized red blood cells were shown by immunohistochemical analysis to possess the platelet glycoprotein CD36, thrombospondin, and intracellular adhesion molecule-1. The formation of rosettes also was observed in the cerebral microvessels. In a fashion similar to human cerebral malaria, P. fragile produced neurological symptoms in the animals. Thus, rhesus monkeys infected with P. fragile, like those monkeys infected with Plasmodium coatneyi, can be used as a primate model to study human cerebral malaria.

Animals↗
PubMed1994

Plasmodium falciparum: the Pf332 antigen is secreted from the parasite by a brefeldin A-dependent pathway and is translocated to the erythrocyte membrane via the Maurer's clefts.

The transport of the megadalton protein Pf332 was studied during the asexual bloodstage development of Plasmodium falciparum. Four mouse monoclonal antibodies, produced against a recombinant polypeptide derived from the Pf332 protein, were used to analyze the kinetics of synthesis, the subcellular location, and transport of this giant molecule to the erythrocyte membrane. After parasite invasion of a red blood cell, the Pf332 antigen is first detected in young trophozoites at the parasitophorous vacuole membrane or in the cytoplasm of the erythrocyte as large vesicle-like structures. The number of vesicles increases during maturation of the parasite and thus forms a rim-like immunofluorescence pattern between the erythrocyte membrane and the parasitophorous vacuole at very late stages. The various anti-Pf332 antibodies react with the surface of erythrocytes infected with very mature parasites (segmenter stage 42-46 hr postinvasion). Immunoelectron microscopic analysis shows that the Pf332 antigen is transported in association with Maurer's clefts in the cytoplasm of the erythrocyte. This transport could be completely blocked by Brefeldin A, resulting in the accumulation of the antigen within the parasite. These data strongly suggest that the Pf332 antigen is exported to the erythrocyte cytoplasm via the classical Golgi secretory pathway.

Animals↗
PubMed1994

Ultrastructural localization of CD36 in human hepatic sinusoidal lining cells, hepatocytes, human hepatoma (HepG2-A16) cells, and C32 amelanotic melanoma cells.

Ultrastructural localization of CD36 in human hepatic sinusoidal lining cells, hepatocytes, human hepatoma (HepG2-A16) cells, and C32 amelanotic melanoma cells. Experimental Parasitology 79, 383-390. CD36 is expressed in the endothelial cells of some human organs, but the ultrastructural localization of this molecule in the sinusoidal lining cells of human liver is not well established. We report the ultrastructural localization of CD36 in the liver using a novel murine monoclonal antibody against CD36, namely MO30, as a primary antibody. Immunocytochemistry by the postembedding method showed that CD36 was localized in endothelial cells of sinusoids and in hepatocyte microvilli protruding into the space of Disse. Moreover, in cultured human hepatoma (HepG2-A16) cells and C32 amelanotic melanoma cells, MO30 reacted with microvilli. Hence, CD36 expressed on these cells may be involved in recognition and/or entry of these cells by malaria sporozoites.

Amino Acid Sequence↗
PubMed1994

Malaria-induced increase of splenic gamma delta T cells in humans, monkeys, and mice.

The number and distribution of gamma delta T cells in spleens from patients who died of cerebral malaria and from rhesus monkeys severely infected with Plasmodium coatneyi were examined by immunocytochemistry. gamma delta T cells were significantly increased in these spleens. In a rodent malaria model using Plasmodium chabaudi adami, an avirulent strain of murine malaria parasites, the degree of parasitemia appears to be modulated by the number of gamma delta T cells in the spleen. As parasitemia increases, these T cells increase in number. At some critical point, gamma delta T cells in collaboration with macrophages and alpha beta T cells apparently start to clear parasitized erythrocytes from the blood, leading to an abatement of the parasitemia, which is followed by a reduction in the number of gamma delta T cells. This gamma delta T cell phenomenon may be responsible for the self-limiting infection in mice.

Animals↗
PubMed1994

Staurosporine inhibits invasion of erythrocytes by malarial merozoites.

Staurosporine, a protein kinase inhibitor, inhibits the invasion of rhesus by Plasmodium knowlesi merozoites with an IC50 of 250 nM. The drug exerts its effects primarily on the merozoite, with little or no effect on the erythrocyte. Okadaic acid, an inhibitor of protein phosphatases, can partially abrogate the inhibitory effects of staurosporine. Staurosporine arrests invasion at a step which is ultrastructurally similar to the arrest caused by cytochalasins B and D: the merozoite attaches, apically reorients, and forms a junction with the erythrocyte, but it does not internalize. These results suggest that protein phosphorylation within the merozoite plays an important role in the internalization step of invasion.

Alkaloids↗
PubMed1994

Cloning and characterization of a novel Plasmodium falciparum sporozoite surface antigen, STARP.

A novel Plasmodium falciparum sporozoite antigen, STARP (Sporozoite Threonine and Asparagine-Rich Protein), detected consistently on the surface of sporozoites obtained from laboratory strains and field isolates, has been identified and cloned, following a systematic approach aimed at isolating novel non-CS sporozoite surface antigens. The 2.0-kb STARP gene has a 5' miniexon/large central exon structure and contains a complex repetitive region encoding multiple dispersed motifs and tandem 45- and 10-amino acid repeats. In sporozoites, transcription of the STARP gene has been conclusively demonstrated by reverse PCR and Northern blot hybridisation and the 78-kDa protein has been localized by immunofluorescence and immunoelectron microscopy to the sporozoite surface. STARP is also expressed in liver stages, as revealed by immunofluorescence assays using antisera raised either to the central repetitive region or the C-terminal non-repetitive region. Expression is also detected in early ring stages, though not in mature erythrocytic or sexual stages. Identification and elucidation of this novel antigen is a step forward in current efforts aimed at developing an effective preerythrocytic-stage malaria vaccine.

Amino Acid Sequence↗
PubMed1994

Cellular location and temporal expression of the Plasmodium falciparum sexual stage antigen Pfs16.

The temporal expression during gametogenesis and the cellular location of the sexual stage specific protein Pfs16, a putative integral membrane protein of Plasmodium falciparum, was investigated using two monoclonal antibodies, 2G7 and 93A3A2. Using sorbitol synchronised, in vitro gametocyte cultures along with immunofluorescence assays, the time at which Pfs16 is first expressed during gametogenesis has been estimated to 35 hours post merozoite invasion. By immunofluorescence assays on thin blood smears monoclonal antibodies specific for Pfs16 react strongly with the gametocyte and also with vesicles within the red blood cell cytoplasm, many of which connect with the gametocyte cell. Purification of parasitophorous vacuole membranes from mature and immature gametocytes and immunoelectron microscopy on gametocytes during gametogenesis have allowed us to locate Pfs16 to the parasitophorous vacuole membrane. During gametogenesis this membrane is shed along with the red blood cell membrane. Immunofluorescence assays and immunoelectron microscopy studies of emerged gametes indicate that in a minority of cases the parasitophorous vacuole membrane along with Pfs16 can be retained to some extent on the gamete surface.

Animals↗
PubMed1994

Demonstration of the target molecule of a protective IgE antibody in secretory glands of Schistosoma japonicum larvae.

We have demonstrated that a mouse monoclonal IgE antibody, SJ18 epsilon.1, recognizes a 97 kDa surface molecule (Sj97) of Schistosoma japonicum larvae and that the antibody induces partial but significant protection against the skin to lung-stage of S. japonicum infection. The antibody stimulates eosinophil- and macrophage-mediated killing of schistosomula in vitro. In the present study, we isolated the putative full-length cDNA of Sj97 by screening a lambda gt11 cDNA library from S. japonicum adult worms with SJ18 epsilon.1. The predicted amino acid sequence of the cDNA showed highly significant homology to that of S. mansoni paramyosin, a potential vaccine candidate for schistosomiasis. The deletion mutants of S. japonicum paramyosin were expressed in Escherichia coli and the translation product of 443 amino acid residues of paramyosin was found to be recognized by the antibody. Moreover, we observed by immunoelectron microscopy the presence of paramyosin in the post-acetabular gland as well as in the tegument and muscle layers of the larvae. These results suggest that paramyosin is a secretory protein which may be incorporated into the tegument during the development of schistosomula, thus becoming a target for protective immunity during the migratory phase of the parasite.

Amino Acid Sequence↗