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Biomedical subjects

M Ikawa

Publications and source records attributed to M Ikawa.

At least 55 records · Page 3Linked to original sources
PubMed1997

The putative chaperone calmegin is required for sperm fertility.

The proper folding of newly synthesized membrane proteins in the endoplasmic reticulum (ER) is required for the formation of functional mature proteins. Calnexin is a ubiquitous ER chaperone that plays a major role in quality control by retaining incompletely folded or misfolded proteins. In contrast to other known chaperones such as heat-shock proteins, BiP and calreticulin, calnexin is an integral membrane protein. Calmegin is a testis-specific ER protein that is homologous to calnexin. Here we show that calmegin binds to nascent polypeptides during spermatogenesis, and have analysed its physiological function by targeted disruption of its gene. Homozygous-null male mice are nearly sterile even though spermatogenesis is morphologically normal and mating is normal. In vitro, sperm from homozygous-null males do not adhere to the egg extracellular matrix (zona pellucida), and this defect may explain the observed infertility. These results suggest that calmegin functions as a chaperone for one or more sperm surface proteins that mediate the interactions between sperm and egg. The defective zona pellucida-adhesion phenotype of sperm from calmegin-deficient mice is reminiscent of certain cases of unexplained infertility in human males.

Animals↗
PubMed1997

'Green mice' as a source of ubiquitous green cells.

The green fluorescent protein (GFP) is responsible for the green bioluminescence of the jellyfish Aequorea victoria. Many classes of GFP mutants exist that display modified fluorescence spectra and an increased extinction coefficient. We produced transgenic mouse lines with an 'enhanced' GFP (EGFP) cDNA under the control of a chicken beta-actin promoter and cytomegalovirus enhancer. All of the tissues from these transgenic lines, with the exception of erythrocytes and hair, were green under excitation light. The fluorescent nature of the cells from these transgenic mouse lines would facilitate their use in many kinds of cell transplantation experiments.

Actins↗
PubMed1997

The regulation of membrane cofactor protein (CD46) expression by the 3' untranslated region in transgenic mice.

Regulation of the membrane cofactor protein (MCP: CD46) was examined. While the expression of MCP in mice carrying MCP(BC2) cDNA with 125 bp of 3' untranslated region (3'UT) was minimal, that in mice carrying MCP cDNA without total 3' UT was evident in many organs. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis clearly showed the presence of mRNA even in transgenic mice with 3' UT, suggesting that the expression was regulated at the post-transcriptional stage. The in vitro expression data of MCP molecules on the stable Chinese hamster ovary (CHO) cell clone corresponded to that in transgenic mice. The first 125 bp downregulated the expression of MCP molecules in combination with not only beta-actin, but also SR alpha, promoter. Also, this region inhibited expression of decay accelerating factor (DAF: CD55) molecules when it was inserted into cDNA of DAF. Furthermore, the first 32 bp of the 3' UT revealed the same downregulation effect as 125 bp on MCP molecules. These findings indicated that the first 125 bp (and the first 32 bp in particular) of 3' UT regulate the expression of MCP molecules in transgenic mice.

Animals↗
PubMed1997

Transcriptional activation of a hybrid promoter composed of cytomegalovirus enhancer and beta-actin/beta-globin gene in glomerular epithelial cells in vivo.

The aim of this study was to seek a promoter, transactivated selectively in renal cells in vivo by using transgenic (tg) mouse technology. We generated two kinds of tg mouse lines carrying a green fluorescence protein (GFP) cDNA driven either by cytomegalovirus enhancer and beta-actin/beta-globin promoter (CX-GFP) or by elongation factor 1alpha promoter (EF-GFP), and investigated the expression of GFP in the kidney. Microscopic examination of the renal tissues in CX-GFP-tg mice revealed that GFP was expressed only in glomeruli, mainly epithelial cells, but not in tubules, arteries and interstitium. Moreover, in situ hybridization demonstrated that GFP mRNA expression was localized in the glomerular cells. In contrast, GFP was not detectable in the kidney in any of the lines of EF-GFP-tg mouse. To exclude the possible involvement of the GFP cDNA as an enhancer, we constructed tg mice carrying the CX promoter driving a human CD4 cDNA. It was confirmed that the expression patterns of human CD4 in the kidney were quite similar to those of GFP in the kidney of CX-GFP-tg mice. These results strongly suggest that CX promoter could be transactivated in glomerular epithelial cells in vivo.

Actins↗
PubMed1996

Glycosylphosphatidylinositol-anchor-deficient mice: implications for clonal dominance of mutant cells in paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder characterized by complement-mediated hemolysis. Abnormal hematopoietic cells from patients with PNH are deficient in glycosylphosphatidylinositol (GPI)-anchored proteins and clonally dominate various hematopoietic lineages in the bone marrow and the peripheral blood. Analysis of many patients with PNH has showed that somatic mutation in the X-linked gene PIG-A is responsible for the GPI-anchor deficiency in PNH. The PIG-A mutation must also be relevant to the clonal dominance of GPI-anchor deficient (GPI-) blood cells because two or more PIG-A mutant clones become dominant in many patients. However, whether the PIG-A mutation alone is sufficient for clonal dominance is not known. To address this question, we generated chimeric mice using Pig-a (the murine homologue of PIG-A) disrupted embryonic stem (ES) cells, in which the animals are chimeric with respect to the surface expression of GPI-anchored proteins. The chimerism of hematopoietic and nonhematopoietic tissues in such mice was always low, suggesting that the higher contribution of Pig-a disrupted GPI- cells had a lethal effect on the chimera. GPI- cells appeared in the peripheral blood of some of the chimeric mice. However, the percentage of GPI- erythrocytes did not increase for 10 months after birth, implying that the Pig-a mutation alone does not immediately cause the clonal dominance of GPI- blood cells; another pathologic or physiologic change(s) in the hematopoietic environments or in the clone itself may be necessary.

Animals↗
PubMed1996

[Intra-arterial infusion chemotherapy for breast cancer].

In order to reduce toxic effects while attaining maximal therapeutic effects, epirubicin 10 mg/day, cyclophosphamide 100 mg/day and prednisolone 10 mg/day were administered through in indwelling catheter inserted into the internal mammary artery and/or subclavian artery for 3-4 weeks, employing the implantable port system for the treatment of unresectable breast cancer and recurrent cancer. Ten out of 11 patients (91%) with unresectable breast cancer showed a response (CR 3, PR 7, NC 1) to this modality of intra-arterial infusion chemotherapy. Seven out of 11 patients (64%) with recurrent cancer of the breast showed a response (CR 1, PR 6, NC 4). Intraarterial infusion chemotherapy for the unresectable advanced breast cancer and recurrent breast cancer proved to be an effective modality of treatment.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

A rapid and non-invasive selection of transgenic embryos before implantation using green fluorescent protein (GFP).

Non-invasive selection of transgenic mice was performed at the stage of preimplantation embryos. The morulae collected from wild female mated with hemizygous transgenic male expressing Aequorea victoria green fluorescent protein (GFP) under chicken beta-actin promoter could be classified as green or non-green under a fluorescent microscope. All the green embryos were shown to carry the transgene by PCR analysis. Taking advantage of the detection of GFP expression can be done non-invasively, the selected embryos were demonstrated to be able to developed to term with 100% of accuracy of the selection.

Animals↗
PubMed1995

Improvement of fusing ability of human sperm to zona-free hamster eggs by conditioned media.

A conditioned medium (CM) was prepared by culturing human sperm at 3.0 x 10(6) sperm/ml for 12 h. The fusion index increased significantly when the sperm penetration assay (SPA) was performed with CM (0.6 without CM to 2.0 with CM). The conditioned medium was also effective on the sperm from 11 patients who showed a low or zero value in SPA and who's in vitro fertilization treatment failed. When CM from the sperm of healthy donors was added to these patients' sperm, the fusing ability to zona free hamster eggs was significantly restored.

Acrosome↗
PubMed1994

Optical characteristics of human extracted teeth and the possible application of photoplethysmography to the human pulp.

In order to record pulp blood flow by photoplethysmography, the light transmission properties of extracted human teeth and human peripheral blood at wavelengths between 400 and 800 nm were first investigated. Transmission through peripheral blood and extracted teeth was lower at wavelengths shorter than 600 nm. Transmitted-light photoplethysmography (TLP) was applied to teeth in situ using a tungsten light, or one of two light-emitting diodes (LED) with peak wavelengths of 565 and 695 nm. A CdS-CdSe photoconductive cell was used as a detector. The LED with a peak intensity at 565 nm was the most efficient of the three light sources for recording the TLP. The results indicate that the TLP could be used to assess pulp vitality.

Adult↗
PubMed1993

[An analysis of prognostic factors in patients with prostatic cancer after hormone therapy and radiotherapy].

To investigate prognostic factors for prostatic cancer, 110 patients who had received hormonal treatment (HT) and 43 patients who had received radiotherapy (RT) were studied. Age of the patients ranged from 49 to 92 years old (median 71 years old) and follow-up period ranged from 3 to 164 months (median 50 months). Survival rate was calculated by Kaplan-Meier method with statistical analysis based upon Cox's proportional hazards regression model. This analysis identified performance status as the most important factor for al patients, followed by histological grade for patients HAVING received HT, and lymph node metastasis for patients received having RT. The result suggests that routine clinical data provide a good indicator as to the prognosis of prostatic cancer.

Aged↗
PubMed1992

Homology of an acrosome-reacted sperm-specific antigen to CD46.

MH61 is an acrosome-reacted sperm-specific monoclonal antibody. The antibody-coated beads effectively analyze the acrosomal status of human sperm. However, the nature of the antigen was not known. The antigen was purified by immunoprecipitation and SDS-PAGE followed by blotting on PVDF paper. The N-terminal sequence of the antigen was analyzed by an automated protein sequencer. An exactly matching sequence was found in CD46, that is also known as a membrane cofactor protein.

Acrosome↗
PubMed1991

Parotid protein secretion from the rabbit during feeding.

Rabbits were trained to accept a standardized feeding regime. Under anaesthesia both parotid ducts were cannulated in a retrograde direction and saliva was subsequently collected in feeding sessions involving pellets and carrots before and after the administration of propranolol. Salivary total protein and amylase concentrations were assayed and protein analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Propranolol produced a reduction in protein secretion but not fluid secretion, indicating that protein secretion is partly under beta-adrenergic control. A transient increase in protein secretion was seen 8 h after the administration of propranolol and suggested the existence of different neural mechanisms involved in protein secretion compared to synthesis. Protein output (with high fluid secretion) during feeding on pellets was higher than on carrots (with high protein concentration) and suggested a significant role of the parasympathetic nervous system. The pattern of protein secretion as seen by SDS-PAGE was similar in individual rabbits and remained largely unchanged with the different foods and in the presence of propranolol.

Amylases↗
PubMed1990

Quantification of acute phase proteins in rat serum and in the supernatants of a cultured rat hepatoma cell line and cultured primary hepatocytes by an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) has been developed to measure acute phase reactants (APRs) in rat serum. Rat APRs of alpha 2-macroglobulin, alpha 1-acid glycoprotein (AGP), haptoglobin (Hp), haemopexin (Hpx), cysteine protease inhibitor (CPI), albumin (Alb) and transferrin (Tf) were purified from the plasma of turpentine treated rats. Fab' fragments from each IgG fraction were labelled with horseradish peroxidase (POD) by the maleimide method and the assay was performed using a sandwich technique. This ELISA procedure was able to measure nanogram quantities of rat serum APRs.

Acute-Phase Proteins↗
PubMed1990

[Photoplethysmograph obtained from a small area of human gingiva].

We have established a method to observe circulation in a small area of the human gingiva. Reflected light photo-plethysmographs (RLP) and transilluminated light photo-plethysmographs (TLP) were recorded from healthy gingiva in 2 young adults of twenties. A tungsten-lamp, connected to a stabilized power source, was used to illuminate the gingiva. The reflected or transilluminated light was collected using a fibre-optic bundle. A CdSe photo-conductive cell was used as the photo-detector. The ECG was recorded simultaneously. The results were as follows: 1) RLP and TLP were both synchronous with the heart beat and showed a dicrotic-notched wave form. 2) When the light-collecting fibre was 0.5 mm from the surface of the gingiva, the dicrotic notch with TLP was clearer than that with RLP. 3) When the light-collecting fibre was placed less than 0.5 mm from the gingival surface, clear dicrotic notches were seen in RLP. 4) When the surface of the gingiva was covered with white opaque paint to prevent transilluminated light, definite dicrotic notches were observed with RLP. 5) RLP was produced mainly by the pulsation of the gingival surface, and the pulsatile movement of the tooth had a little effect on RLP. 6) RLP was consisted from the light reflected from the surface of the gingiva and also from the light reflected after penetrating some distance in the gingival tissue.

Adult↗
PubMed1989

[Analysis on deformity of disk associated with internal derangement of TMJ].

Internal derangement of temporomandibular joint has been studied mainly arthrographically about disk position, but it was reported that morphologic alterations and histo-chemical changes of disk were frequently observed in joints with internal derangement. The aim of this investigation was to study the relationship between deformity of disk and the kind of internal derangement of TMJ (anterior disk displacement with or without reduction). We analysed arthrographically the configuration of anterior displaced disk according to the criteria of Westesson. Deformity of disk was seen in 35 joints in 60 joints (58.3%) associated with anterior disk displacement with reduction, and 51 joints in 66 joints (77.3%) without reduction. Statistically significant difference existed between the distribution of disk configuration in with-reduction and without-reduction. We analysed the relationship between distribution of disk configuration and age, clicking period and locking period. In cases long suffering from clicking and locking, no-deformed disk were seen, and any certain type of deformed disk did not increase. From above results it was suggested that there was a strong relationship between distribution of disk configulation and types of anterior disk displacement (with or without reduction).

Arthrography↗