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Biomedical subjects

H Hamada

Publications and source records attributed to H Hamada.

At least 307 records · Page 17Linked to original sources
PubMed1996

Changes in markers, receptors and adhesion molecules expressed on murine hemopoietic stem cells after a single injection of 5-fluorouracil.

Cytokines play a crucial role in the differentiation and proliferation of hemopoietic cells, and it has recently been found that adhesion molecules play crucial roles not only in differentiation and proliferation, but also in the homing and other functions of hemopoietic cells. We have very recently established a new method for purifying pluripotent hemopoietic stem cells (P-HSC) in mice by injecting 5-fluorouracil (5-FU). The P-HSC were found to be low-density, lineage marker-negative (Lin-), CD71- and major histocompatibility complex class I(high). In the present study, we analyze changes in the expression of various HSC markers (Sca-1 and CD34), receptors (c-kit and interleukin-6 receptor [IL-6R]) and adhesion molecules (very late activation antigen-4 [VLA-4], lymphocyte function-associated antigen-1 [LFA-1], and CD44) after 5-FU injection. The percentage of Sca-1+ cells increases after 5-FU treatment, reaching a maximum on day 3, whereas the percentage of IL-6R+ cells decreases, reaching a minimum on day 3. The percentage of CD34+ cells does not change after 5-FU treatment. The percentages of both c-kit(low) and c-kit(high) cells decrease, reaching a minimum on day 3 after 5-FU treatment, whereas the percentage of c-kit- cells reciprocally increases, reaching a maximum on day 3. However, there is no change in the expression of adhesion molecules (VLA-4, LFA-1 and CD44) on the P-HSC.

Animals↗
PubMed1996

Echogenic fetal bowel in the third trimester associated with trisomy 18.

We present the first case of trisomy 18 in which echogenic fetal bowel was detected in the third trimester after normal echogenicity was documented during the second trimester. Fetal karyotyping should be considered in cases of increased echogenicity of the fetal lower abdomen in the second as well as the third trimester.

Abnormalities, Multiple↗
PubMed1996

Measurement of ventricular volumes by cine magnetic resonance imaging in complex congenital heart disease with morphologically abnormal ventricles.

This study assessed the validity of cine magnetic resonance imaging (MRI) for measuring right and left ventricular volumes by using Simpson's rule in children with complex congenital heart disease. Forty-five patients with complex congenital heart disease (average age 2.6 years) and 10 controls (average age 2.3 years) were evaluated. The whole heart was encompassed by contiguous transverse sections. Ventricular volumes were calculated by adding luminal areas determined in each section at end diastole and end systole. End-diastolic and end-systolic volumes by MRI in both groups correlated well with those by ventriculography (r>0.89). Comparison of the ejection fraction in both ventricles in both groups yielded a good correlation between MRI and ventriculography (r>0.67). MRI technique in both groups had low intraobserver and interobserver variation (<6%). Cine MRI provides a suitable noninvasive means of quantifying ventricular volume in children with complex congenital heart disease.

Child↗
PubMed1996

Identification of putative downstream genes of Oct-3, a pluripotent cell-specific transcription factor.

BACKGROUND: Oct-3, a pluripotent cell-specific POU transcription factor, appears to be a key regulator in pluripotential early embryonic cells and germ cells. In order to study how pluripotency is maintained, it is essential to know what genes are regulated by Oct-3. RESULTS: By employing a subtraction method, we identified several pluripotent cell-specific genes. Based upon expression patterns in various cell lines lacking or possessing Oct-3 function, about half of the genes were placed downstream of Oct-3. These downstream genes included a previously-known gene (Glut-3: a gene for a glucose transporter) and novel genes (226, 383 and 880). Their expression patterns paralleled that of Oct-3: all of these genes were highly expressed in pluripotent cells such as EC/ES cells, but switched off upon differentiation. More importantly, their expression was rescued in 'revertant' cells that ectopically acquired the Oct-3 transactivating function. Furthermore, the expression profiles of Glut-3, 226 and 383 during mouse development also overlapped that of Oct-3. The Glut-3 gene possessed multiple Oct-3 binding sites in its transcriptional regulatory regions, suggesting that at least one of the downstream genes was a direct target of Oct-3. CONCLUSIONS: A large proportion of pluripotent cell-specific genes appear to be downstream targets of Oct-3.

Amino Acid Sequence↗
PubMed1996

Tumor-specific gene expression in carcinoembryonic antigen--producing gastric cancer cells using adenovirus vectors.

BACKGROUND & AIMS: An increase of carcinoembryonic antigen (CEA) expression is noted in about 40% of patients with gastric cancer. Adenovirus-mediated gene therapy using the CEA promoter was investigated as a way to specifically target human CEA-producing gastric tumors. METHODS: Recombinant adenovirus vectors carrying a CEA promoter linked to the lacZ gene (AdCEA lacZ) or the cytosine deaminase gene (AdCEA-CD) were constructed. After infection with these vectors, CEA-producing (MKN45 and MKN28) and non-CEA-producing (MKN1) gastric cancer cells were analyzed for transgene expression and sensitivity to 5-fluorocytosine. RESULTS: The lacZ gene was expressed selectively in CEA-producing AdCEA-lacZ-infected cells in vitro and in vivo. Transduction of the vector containing the CEA-regulated cytosine deaminase gene (AdCEA-CD) resulted in extraordinary sensitivity of MKN45 and MKN28 cells to 5-fluorocytosine. This effect was not observed in MKN1 cells. Moreover, AdCEA-CD-infected MKN45 cells showed a profound in vitro neighbor cell killing effect in the presence of 5-fluorocytosine. This effect was attributed to the diffusion of 5-fluorouracil, resulting from conversion of 5-fluorocytosine to 5-fluorouracil by the cytosine deaminase-expressing cells. CONCLUSIONS: The results of this study suggest that use of a CEA promoter in an adenovirus vector could confer selective expression of the cytosine deaminase gene in CEA-producing gastric cancer cells, rendering the transduced cells susceptible to 5 fluorocytosine. This system may be useful in gene therapy that targets CEA-producing gastric carcinomas.

Adenoviridae↗
PubMed1996

Bcl-2 inhibits retinoic acid-induced apoptosis during the neural differentiation of embryonal stem cells.

We report here that all trans-retinoic acid (RA), a classical morphogen, induces apoptosis during the neural differentiation of the embryonic stem cell line P19. The apoptotic cells showed, in addition to DNA cleavage, typical morphological changes including chromatin condensation, nuclear fragmentation, and cytoplasmic vacuolation. These apoptotic changes became obvious by 12 h after the addition of RA. The endogenous expression of bcl-2 in surviving cells was down-regulated during this process, and the compelled expression of bcl-2 by retroviral vectors reduced the number of apoptotic cells. Apoptosis was partially inhibited by adding antisense oligonucleotides against RA receptors (RARs) simultaneously or by transfecting a plasmid vector flanked with a RA-responsive element. Antisense oligonucleotides against retinoid X receptors (RXRs), the receptors for 9 cis-RA, did not inhibit apoptosis induced by all trans-RA. Cycloheximide and actinomycin D, inhibitors of protein and RNA syntheses, respectively, suppressed apoptosis. No changes were seen in the expression of tumor necrosis factors, their receptors, Fas, FasL, p53, or c-myc, molecules which have been suggested to participate in the apoptotic process. Addition of neurotrophins to the culture medium did not affect apoptosis. These findings suggest that the signals themselves, promote expression of molecules essential for apoptosis. Furthermore, we observed that RA induced apoptosis of cerebral neurons from murine embryos in primary culture, which suggests that RA might participate in cell death which occurs during neural development.

Animals↗
PubMed1996

A case of chromomycosis with tumor-like growth.

A 66-year-old woman who lived on Tokunoshima Island, a small and remote southern island of the Japanese archipelago, had suffered from chromomycosis for more than 30 years and presented with a tumor-like growth on the posterior crural region of his right leg. Fonsecaea pedrosoi was identified as the pathogen from its growth pattern and micromorphological characteristics. The patient was successfully treated with 5-fluorocytosine, itoraconazole, and topical thermotherapy.

Administration, Topical↗
PubMed1996

Two new members of the murine Sim gene family are transcriptional repressors and show different expression patterns during mouse embryogenesis.

From a cDNA library of mouse skeletal muscle, we have isolated mouse Sim1 (mSim1) cDNA encoding a polypeptide of 765 amino acids with striking amino acid identify in basic helix-loop-helix (89% identify) and PAS (89 % identify) domains to previously identified mSim2, although the carboxy-terminal third of the molecule did not show any similarity to mSim2 or Drosophila Sim (dSim). Yeast two-hybrid analysis and coimmunoprecipitation experiments demonstrated that both of the mSim gene products interacted with Arnt even more efficiently than AhR, a natural partner of Arnt, suggesting a functional cooperativity with Arnt. In sharp contrast with dSim having transcriptional-enhancing activity in the carboxy-terminal region, the two mSims possessed a repressive activity toward Arnt in the heterodimer complex. This is the first example of bHLH-PAS proteins with transrepressor activity, although some genetic data suggest that dSim plays a repressive role in gene expression (Z. Chang, D. Price, S. Bockheim, M. J. Boedigheimer, R. Smith, and A. Laughon, Dev. Biol. 160:315-322, 1993; D. M. Mellerick and M. Nirenberg, Dev. Biol. 171:306-316, 1995). Whole-mount in situ hybridization showed restricted and characteristic expression patterns of the two mSim mRNAs in various tissues and organs during embryogenesis, such as those for the somite, the nephrogenic cord, and the mesencephalon (for mSim1) and those for the diencephalon, branchial arches, and limbs (for mSim2). From sequence similarity and chromosomal localization, it is concluded that mSim2 is an ortholog of hSim2, which is proposed to be a candidate gene responsible for Down's syndrome. The sites of mSim2 expression showed an overlap with the affected regions of the syndrome, further strengthening involvement of mSim2 in Down's syndrome.

Amino Acid Sequence↗
PubMed1996

cDNA cloning and tissue-specific expression of a novel basic helix-loop-helix/PAS factor (Arnt2) with close sequence similarity to the aryl hydrocarbon receptor nuclear translocator (Arnt).

We isolated mouse cDNA clones (Arnt2) that are highly similar to but distinct from the aryl hydrocarbon receptor (AhR) nuclear translocator (Arnt). The composite cDNA covered a 2,443-bp sequence consisting of a putative 2,136-bp open reading frame encoding a polypeptide of 712 amino acids. The predicted Arnt2 polypeptide carries a characteristic basic helix-loop-helix (bHLH)/PAS motif in its N-terminal region with close similarity (81% identity) to that of mouse Arnt and has an overall sequence identity of 57% with Arnt. Biochemical properties and interaction of Arnt2 with other bHLH/PAS proteins were investigated by coimmunoprecipitation assays, gel mobility shift assays, and the yeast two-hybrid system. Arnt2 interacted with AhR and mouse Sim as efficiently as Arnt, and the Arnt2-AhR complex recognized and bound specifically the xenobiotic responsive element (XRE) sequence. Expression of Arnt2 successfully rescued XRE-driven reporter gene activity in the Arnt-defective c4 mutant of Hepa-1 cells. RNA blot analysis revealed that expression of Arnt2 mRNA was restricted to the brains and kidneys of adult mice, while Arnt mRNA was expressed ubiquitously. In addition, whole-mount in situ hybridization of 9.5-day mouse embryos showed that Arnt2 mRNA was expressed in the dorsal neural tube and branchial arch 1, while Arnt transcripts were detected broadly in various tissues of mesodermal and endodermal origins. These results suggest that Arnt2 may play different roles from Arnt both in adult mice and in developing embryos. Finally, sequence comparison of the currently known bHLH/PAS proteins indicates a division into two phylogenetic groups: the Arnt group, containing Arnt, Arnt2, and Per, and the AhR group, consisting of AhR, Sim, and Hif-1alpha.

Amino Acid Sequence↗
PubMed1996

Preferential differentiation of P19 mouse embryonal carcinoma cells into smooth muscle cells. Use of retinoic acid and antisense against the central nervous system-specific POU transcription factor Brn-2.

Investigation of the molecular mechanisms that control smooth muscle cell (SMC) development and differentiation is a prerequisite in understanding the regulatory mechanisms of physiological and pathological SMC-associated vascular processes. The pluripotent murine embryonal carcinoma P19 cell, whose developmental potential resembles that of early embryonic cells, can develop into cell types derived from the neuroectoderm, mesoderm, and endoderm. In the present study, we have shown a unique strategy to enhance SMC differentiation in P19 cells. Under chemical induction of high concentrations of retinoic acid (1 micromol/L), P19 cells showed optimum differentiation into SMCs. Because the P19 cells thus induced also showed differentiation into neuronal cells, a strategy to block neuronal lineage differentiation was developed using a stable transformant antisense RNA construct against Brn-2, a neuronal lineage-specific POU-domain transcription factor; thus, by specifically inhibiting neuronal differentiation, enhanced SMC differentiation by P19 cells was attained. SMC expression was confirmed by immunohistochemical staining, RNA analysis (RNase protection assay), and protein analysis (Western blot) using SMC-specific markers (eg, SM1 and calponin) and alpha-smooth muscle actin. Our results show that the pathway of SMC differentiation may provide an in vitro system useful in the investigation of SMC regulatory mechanisms (eg, transcriptional regulation) and in the further understanding of SMC development and differentiation.

Amino Acid Sequence↗
PubMed1996

Chemical modification of earthworm fibrinolytic enzyme with human serum albumin fragment and characterization of the protease as a therapeutic enzyme.

The strongest fibrinolytic protease (F-III-2) in the six enzyme proteins purified from earthworm, Lumbricus rubellus [N. Nakajima et al., Biosci. Biotech. Biochem., 57, 1726-1730 (1993)] has been modified chemically with fragmented human serum albumin (mol. wt., 10,000-30,000). The modified enzyme lost the antigenicity of the native enzyme and reacted with the antisera against human serum albumin, the human serum albumin fragments, and the conjugate with the native enzyme to form precipitation lines, which fused with each other. The conjugate was significantly more resistant to inactivation by protease inhibitors in rat plasma. The enzyme was a non-hemorrhagic protein and did not induce platelet aggregation. The enzyme kept potent proteolytic activity for fibrin and fibrinogen than that of human plasmin. The enzyme easily solubilized actual fibrin clots (thrombi) of whole blood induced by thrombin in a rat's vena cava. The continuous fibrinolysis for fibrin suspension in an enzyme reactor system using the modified enzyme immobilized to oxirane-activated acrylic beads has been achieved without any inactivation of the activity at least for more than 1 month. The N-terminal amino acid sequence of the protein was also investigated and the sequence showed local similarity to those of the serine proteases such as plasmin and chymotrypsin.

Amino Acid Sequence↗
PubMed1996

[Monoclonal antibody against an urinary protein secreted from the renal tubules--immunohistochemical analysis of renal cell carcinoma].

BACKGROUND: Monoclonal antibodies (mABs) against urinary proteins originated from renal tubules were obtained in order to find a possible tumor marker for renal cell carcinoma. METHODS: Urine samples were collected from healthy adult males. After removal of Thamm-Horsfall protein (THP) by sodium chloride precipitation, supernatant urine was ultrafiltered, thus, THP-free urinary proteins were obtained. Then, proteins of plasma origin were removed by circulating the urinary proteins through an affinity column which contained immobilized rabbit anti-human whole serum immunoglobulins. BALB/c mice were immunized with the THP- and plasma protein-free urinary proteins. The spleen cells were fused with mouse myeloma cells. Hybridomas were screened by indirect immunofluorescence of fresh frozen kidney tissue sections using culture supernatants. RESULTS: Five hybridomas producing mAbs which reacted with renal tubular segments were established. One mAb reacted strongly with distal renal tubules. Using this mAb, formalin fixed and paraffin embedded sections of 39 renal cell carcinomas were stained by immunoperoxidase method. Twenty-six of the 39 cancer tissues (66.7%) were stained positive. According to the histological classification, positive staining rate of clear cell subtype, and mixed subtype was 75% (6/8), 80% (8/10) and 66.7% (6/9), respectively. According to the tumor grade, positive staining rate of G1, G2, G3 was 66.7% (6/9), 71.4% (15/21) and 55.5% (5/9), respectively. CONCLUSION: These findings indicate that most of renal cell carcinomas were originated from common precursor cells for both proximal and distal tubules, because normal proximal tubular cells were not stained by the mAb.

Adult↗
PubMed1996

[Two cases of von Recklinghausen's disease with diffuse pulmonary changes].

Two patients with von Recklinghausen's disease had diffuse pulmonary diseases. The pulmonary diseases were interstitial fibrosis and emphysematous bullae. In case 2, examination of a specimen obtained by transbronchial lung biopsy revealed fibrotic interstitial thickening and adenomatous hyperplasia. Diffuse pulmonary abnormalities in von Recklinghausen's disease have been said to be fibrotic changes and emphysematous changes, as shown in roentgenograms in these two cases. The biopsy specimen obtained in case 2, however, revealed fibrotic changes only, which could not be distinguished from findings in cases of idiopathic interstitial pneumonia. In case 2, bronchoalveolar lavage fluid was also examined but it did not reveal any unique features of von Recklinghausen's disease. Since 1978, von Recklinghausen's disease has been diagnosed 10 times in our hospital, but diffuse pulmonary diseases was seen in only two of those 10 cases.

Adult↗