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Biomedical subjects

H Toyoshima

Publications and source records attributed to H Toyoshima.

At least 91 records · Page 5Linked to original sources
PubMed1994

Human ltk receptor tyrosine kinase binds to PLC-gamma 1, PI3-K, GAP and Raf-1 in vivo.

Leukocyte tyrosine kinase (ltk) is a receptor-type tyrosine kinase which is suggested to be expressed in hematopoietic cells and neuronal cells in human. Recently we have cloned a full sized human ltk cDNA which has a 423 amino acid extracellular domain which may bind to unknown ligand(s), and a 415 amino acid cytoplasmic domain which contains a tyrosine kinase domain. To identify the cellular signal transducer proteins binding to the ltk protein, we have analysed the recombinant ltk protein transiently expressed in COS cells. By an in vitro immune complex kinase assay, a major 140 kDa phosphoprotein and other cellular phosphoproteins were co-immunoprecipitated with the 100 kDa ltk protein using anti-ltk monoclonal antibodies. Western blot analysis revealed that the wild-type ltk protein was tyrosine-phosphorylated in vivo and associated with SH2 containing proteins, PLC-gamma 1, p85 subunit of PI3-K and GAP, in vivo. Furthermore, the wild-type ltk protein also binds to a serine/threonine kinase, Raf-1, in vivo. In contrast, none of these signal transducer proteins were associated with a kinase-negative ltk mutant (K544M-ltk) in which methionine at the putative ATP binding site was replaced with lysine. These results suggest that the associations of the ltk protein with those signaling molecules depend on the tyrosine kinase activity of the ltk protein. This is the first detection of cytoplasmic signal transducers that bind to the ltk protein in vivo.

Base Sequence↗
PubMed1994

[Effects of liposome-entrapped E. coli endotoxin on lung pathophysiology in rats].

The effects of repeated intravenous injections of E. coli endotoxin (ETX)-containing liposomes (LP) on the development of emphysematous change in rats were examined. Male Wistar rats, weighting 150-200 g, were divided into 3 groups. Group 1; rats treated with phosphate buffered saline (PBS), Group 2; rats treated with liposome-entrapped PBS, Group 3; rats treated with liposome-entrapped ETX (10 mg/ml). In each group, 0.5 ml was injected intravenously once a week for 8 consecutive weeks. After 8 weeks, functional and morphometrical analyses of lungs were performed. Functional residual capacity (FRC), total lung capacity (TLC), and static compliance (Cst.) were measured using a pressure plethysmograph for small animals. Mean linear intercept (MLI) and internal surface area (ISA) were also determined. TLC did not differ among the 3 groups. In rats treated with liposome-entrapped ETX, Cst. corrected by body weight (Cst./body weight) was significantly increased compared with that in liposome-entrapped PBS-treated rats. Further more, MLI was larger than that of the other 2 groups and ISA was less than that of the liposome-entrapped PBS-treated rats. These results suggest that liposome-entrapped ETX induces emphysematous changes in rats.

Animals↗
PubMed1994

The C-terminal SH3 domain of the mouse c-Crk protein negatively regulates tyrosine-phosphorylation of Crk associated p130 in rat 3Y1 cells.

We have isolated the mouse c-crk cDNA from a mouse liver cDNA library. It encodes 304 amino acids and consists mainly of SH2/SH3 regions. In Northern blot analysis, the mouse c-crk mRNA is expressed ubiquitously in every tissue and organ, suggesting that the c-Crk protein may be a common signal transducing molecule among tissues. In contrast to the v-Crk protein, which has a single SH3 domain, the c-Crk protein contains two, the more N-terminal SH3(1) domain and the C-terminal SH3(2) domain. To elucidate functions of these SH3 domains, we have constructed two c-crk mutants, B-crk and D-crk, which lack the SH3(2) and the SH3(1) domain, respectively. These mutants were expressed in rat 3Y1 cells, and examined for their transforming ability in terms of morphological phenotypes and for tyrosine phosphorylation profiles of cells expressing the mutant proteins. Morphological alteration and increased tyrosine phosphorylation of 130-140 kDa proteins, the major component of which is the Crk-associated p130, were observed in cells expressing B-Crk as well as those expressing v-Crk, but little in cells expressing c-Crk even at a similar level of expression. Although a highly tyrosine-phosphorylated form of the p130 was coimmunoprecipitated with c-Crk as well as B-Crk, the relative level of tyrosine phosphorylation of the p130, which is normalized to the amount of Crk protein immunoprecipitated, was 10 to 20 times higher in B-Crk-expressing cells than in c-Crk- or D-Crk-expressing cells. The present results indicate that the SH3(2) domain of mouse c-Crk protein negatively regulates tyrosine phosphorylation of the p130, and that lack of the SH3(2) domain in B-Crk and v-Crk may contribute, at least partly, to their morphological alteration or transforming ability through increasing tyrosine phosphorylation of the p130.

Amino Acid Sequence↗
PubMed1993

Genomic binding-site cloning reveals an estrogen-responsive gene that encodes a RING finger protein.

Estrogen receptor (ER)-binding fragments were isolated from human genomic DNA by using a recombinant ER protein. Using one of these fragments as a probe, we have identified an estrogen-responsive gene that encodes a putative zinc finger protein. It has a RING finger motif present in a family of apparent DNA-binding proteins and is designated estrogen-responsive finger protein (efp). efp cDNA contains a consensus estrogen-responsive element at the 3' untranslated region that can act as a downstream estrogen-dependent enhancer. Moreover, efp is regulated by estrogen as demonstrated at both the mRNA and the protein level in ER-positive cells derived from mammary gland. These data suggest that efp may represent an estrogen-responsive transcription factor that mediates phenotypic expression of the diverse estrogen action. Thus, the genomic binding-site cloning may be applicable for isolation of the target genes of other transcription factors.

Amino Acid Sequence↗
PubMed1993

Differently spliced cDNAs of human leukocyte tyrosine kinase receptor tyrosine kinase predict receptor proteins with and without a tyrosine kinase domain and a soluble receptor protein.

Leukocyte tyrosine kinase (LTK) is a tyrosine kinase that has been suggested to be specific for hematopoietic cells and neuronal cells and reported as an unusual membrane protein lacking an extracellular domain. Here we report the cloning of a human LTK cDNA clone containing the complete open reading frame of a putative receptor tyrosine kinase protein. The extracellular domain of the receptor protein is larger than previously predicted. Furthermore, we have cloned a set of cDNAs representing differently spliced human LTK mRNAs. These cDNAs predict a truncated receptor protein lacking the tyrosine kinase domain and a soluble receptor protein that has neither a transmembrane nor a tyrosine kinase domain. Our results suggest that the LTK gene produces not only the putative receptor tyrosine kinase for unknown ligand but also multiple protein products that may have different functions.

Alternative Splicing↗
PubMed1993

Mutations of the p53 gene in myelodysplastic syndrome (MDS) and MDS-derived leukemia.

The p53 gene is currently thought to be a tumor suppressor gene, and its alterations have been suggested to be involved in the pathogenesis of several human malignancies, including some leukemias and lymphomas. We present here evidence for the possible involvement of p53 gene mutations in the myelodysplastic syndrome (MDS), although the incidence is relatively low. Forty-four patients with MDS and six patients with overt leukemias that developed from MDS were studied for p53 gene alterations using reverse transcriptase-polymerase chain reaction, single-strand conformation polymorphism analysis, and nucleotide sequencing. Three patients with MDS (2 RAEB and 1 RAEB in T) had missense point mutations in the conserved regions of the p53 coding sequence. Furthermore, expression of the wild-type p53 mRNA was not detected in these three patients. The probable absence of normal p53 function in the three cases studied here suggests that alterations in the p53 gene may occasionally play a role in MDS. These three MDS patients with p53 gene mutations and an MDS-derived erythroleukemia cell line that we had previously reported to carry a p53 gene mutation showed no N-ras gene mutations, suggesting heterogeneity in the oncogenic mechanism of MDS.

Amino Acid Sequence↗
PubMed1993

Identification of the human ltk gene product in placenta and hematopoietic cell lines.

Two different monoclonal antibodies (MAbs) were raised against an extracellular domain and a C-terminal portion of the human ltk protein which is a receptor-type protein tyrosine kinase. Western blot analysis showed that these MAbs specifically immunoprecipitated a 100 kDa ltk protein which was transiently expressed in COS-1 cells transfected with a human ltk cDNA. By an in vitro immune complex kinase assay using these MAbs, a 100 kDa phosphoprotein was detected in human placenta and hematopoietic cell lines. These data indicate that the ltk gene product expressed in human placenta and hematopoietic cells shows tyrosine kinase activity. This is the first detection of native ltk protein naturally expressed in human cells.

Amino Acid Sequence↗
PubMed1993

Detection of the PML/RAR alpha fusion gene in acute promyelocytic leukemia with a complex translocation involving chromosomes 15, 17, and 18.

We report a case with typical clinical features of acute promyelocytic leukemia (APL) carrying an atypical chromosomal aberration involving chromosomes 15, 17, and 18. Molecular analysis using Southern blot hybridization and reverse transcriptase-polymerase chain reaction (RT-PCR) proved the creation of the PML/RAR alpha fusion gene in this case. These findings support the notion that this fusion is of crucial importance to leukemogenesis of APL.

Base Sequence↗
PubMed1993

Selective zonal change of the renomedullary interstitial cells in hypokalemic rats.

Electron microscopic morphometry was undertaken to quantitate the morphological change of the renomedullary interstitial cells (RIC) of hypokalemic rats by using large montages. Two weeks of potassium depletion resulted in an increase of the RIC, which were restricted to the interbundle region of the inner stripe of the outer medulla. The increase of the RIC is characterized by a preferential increase in volume density (+340.0%; P < 0.01) and numerical density (+61.4%; P < 0.01) in the interbundle region but not in the vascular bundle of the inner stripe or in the inner medulla. The increased RIC in the interbundle region of the inner stripe demonstrated an increase of lipid droplets, which are known to contain prostaglandin precursors. The selective zonal change of RIC with increased lipid droplets is a characteristic lesion of hypokalemic rats and suggests an enhanced vasoactive function of RIC associated with hypokalemic nephropathy.

Animals↗
PubMed1993

Subarachnoid hemorrhage: evaluation with MR imaging.

Thirty-seven magnetic resonance (MR) examinations were performed at 0.5 T in 33 patients with subarachnoid hemorrhage (SAH) caused by a ruptured aneurysm. Images were obtained 2 hours to 75 days after the ictus. Twenty-four proton-density-weighted (long repetition time [TR], short echo time [TE]) images were obtained in the acute stage (< 72 hours after the ictus) of SAH; SAH was hyperintense to brain parenchyma and cerebrospinal fluid in all cases. The detectability of acute SAH on T1- (short TR, short TE) and T2- (long TR, long TE) weighted images was 36% and 50%, respectively. In the subacute and chronic stages (> 3 days after the ictus), the detectability of SAH on T1-, T2-, and proton-density-weighted images was 73%, 31%, and 83%, respectively. Although computed tomography is still the modality of choice for evaluating acute SAH, the authors emphasize that even acute SAH can be reliably demonstrated with MR imaging with the appropriate parameters.

Adult↗
PubMed1993

[The incidence of atherosclerotic lesions of the carotid artery in people of one community].

Carotid sonography were conducted in people of one community (122 males and 243 females) in 1990 and 1991. The intima-media thickness (IMT) in the main trunk and bifurcation-bulb areas of bilateral carotid arteries were measured in 122 males. IMTs of four areas increased with aging. In all cases, the average IMT of the right main trunk was 0.8 +/- 0.1 mm (mean +/- SD) and those of the remaining three areas were 0.9 +/- 0.2 mm. The IMT of the right bifurcation area in males aged 75 years or older was the thickest; i.e., 1.1 +/- 0.3 mm. Therefore, atherosclerotic lesions (AL) were defined as an IMT of 1.5 mm or more. The incidence of AL increased along with aging both in males and females. In those who were less than 65 years old, the incidence in males was 12.8% (10/78) and that in females was 9.0% (12/134). In those who were 65 years old or older, the incidence in males was 31.8% (14/44) and that in females was 26.9% (29/109). The incidence of AL tended to increase rapidly from 65 years of age in both males and females. Moreover, the incidence of AL in bilateral carotid arteries increased along with aging as well. Since IMT, the incidence of AL and that of AL in bilateral carotid arteries increased with aging, we considered that these parameters could be used as indices of the degree of general atherosclerosis.

Adult↗
PubMed1993

Embolic cerebral infarction: MR findings in the first 3 hours after onset.

OBJECTIVE: MR imaging has a high sensitivity for detecting ischemic brain parenchyma. The aim of this study was to evaluate the changes in the signal intensity of infarcted brain parenchyma on MR images obtained within the first 3 hr after the onset of signs and symptoms in patients with embolic cerebral infarction. MATERIALS AND METHODS: We studied MR images of 16 patients who had a diagnosis of embolic cerebral infarction (highly probable according to criteria of the National Institute of Neurological and Communicative Disorders and Stroke). T1-weighted, T2-weighted, and proton density-weighted MR images were obtained within 3 hr after the onset of symptoms. Two neuroradiologists who had no knowledge of the diagnoses reviewed the MR images of these 16 patients and 20 control subjects in random order and evaluated signal-intensity changes in the gray and white matter. RESULTS: On proton density-weighted images, the central and cortical gray matter showed increased signal intensity in 63-69% and 88-94% of the patients, respectively. No abnormalities of the brain parenchyma were apparent on T1-weighted and T2-weighted images obtained within 3 hr after the onset of symptoms. The adjacent white matter appeared hyperintense on long TR images in only a few cases. CONCLUSION: An increased signal intensity in the gray matter on proton density-weighted images was the most characteristic parenchymal change seen on MR images of the brain obtained within 3 hr after embolic cerebral infarction.

Aged↗
PubMed1993

[Effects of theophylline on ventilatory regulation in patients with chronic obstructive pulmonary disease].

The effects and the mechanism of single and long-term administration of theophylline on ventilatory regulation were investigated in patients with chronic obstructive pulmonary disease (COPD). The ventilatory and mouth occlusion pressure (P0.1) responses during CO2 rebreathing were measured before and 4 hours after oral, single administration of theophylline in 15 patients with pulmonary emphysema, 15 patients with asthma and 10 healthy subjects. Ventilatory response to CO2 (VE/PCO2) was increased in patients with asthma and P0.1 response to CO2 (P0.1/PaCO2) was increased in patients with pulmonary emphysema after single theophylline administration. In patients with pulmonary emphysema, the increase in P0.1 was more marked than that in maximum inspiratory pressure static (MIPS). The effect of long-term administration of theophylline was studied in 8 patients with COPD and 8 patients with restrictive lung disease. In patients with COPD, P0.1/PaCO2 was significantly increased and the increase was maintained until three months later. These findings suggest that theophylline is effective in improving ventilatory and occlusion pressure responses to CO2 in patients with asthma probably by its bronchodilating effect, and in patients with pulmonary emphysema by its direct effect on the ventilatory control system.

Administration, Oral↗
PubMed1993

[A case of malignant rheumatoid arthritis with long-term improvement by regular use of cryofiltration plasmapheresis].

A Japanese man, 25 years old, suffered from stiffness, swelling, and pain of his joints in May 1983. He was diagnosed as rheumatoid arthritis and was given steroid unsuccessfully. Then, he was admitted to our hospital in February 1984. Because of the presence of high fever and rash on admission, differential diagnosis of RA from adult Stills disease was difficult. However, skin biopsy disclosed apparent vasculitis, leading to the definite diagnosis of malignant RA (MRA). We could not induce any remission by large dose of steroid including pulse therapy, various immuno-suppressants, and anti-rheumatic agents, because of lack of effectiveness and side effects of the drugs. Double filtration plasmapheresis (PA) was performed, but its beneficial effect soon disappeared. On the other hand, cryofiltration PA caused more beneficial and prolonged effect, resulting in improvement. Thereafter, he was successfully followed on regular use of PA for about 6 years. His condition depended on the interval between PA and next PA and on the volume of filtrated plasma. He died of septicemia on March, 1991. We report here the case of MRA with long time improvement by regular use of cryofiltration PA.

Adult↗
PubMed1993

[Cause of death in autopsied RA patients].

A mortality study was performed based on the data of Annual of the Pathological Autopsy Cases in Japan in 1985-1989. The average life span of the RA patients, revealing 66.5 years in male and 64.6 years in female, was shorter than that of general population in Japan. Of 1,246 autopsied RA cases, the most common causes of death were infections (26.6%), respiratory diseases including interstitial lung disease (17.5%) and amyloidosis (12.5%). Amyloidosis was common among RA cases (25.2%), and it was suggested that RA was the most important underlying disorder of the secondary amyloidosis: in 1985 to 1989, 316 cases of 515 secondary amyloidosis (61.4%) were associated with RA.

Adolescent↗
PubMed1993

[A cross-sectional study on relationships between daily physical activity and concentration of serum cholesterol and body mass index in fifth grade elementary schoolchildren and their parents].

The purpose of this study was to estimate the effects of daily physical activity on serum total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C), body mass index (BMI) and atherogenic index (AI) in 240 fifth grade schoolchildren, their 174 fathers and 212 mothers. Information on daily physical activity was obtained by inquiry with a questionnaire and was also measured directly with a device sensing acceleration of physical movement. In schoolchildren, effect of physical activity on TC, HDL-C and AI was not apparent, but that on BMI was shown. In adult men, HDL-C differed by job classification and increased as the degree of physical labor increased from desk work to light and heavy work. Strength of physical activity using the quotient of total amount of measured physical activity divided by body weight had a significant positive correlation with serum HDL-C (r = 0.20, p < 0.05) and significant negative correlation with AI (r = -0.18, p < 0.05) in adult men. In adult women, daily physical activity did not have a significant correlation to TC, HDL-C, AI or BMI. These results appear to suggest that the effect of daily physical activity on serum cholesterol, AI, BMI of schoolchildren and adult women was smaller than that for adult men.

Adult↗
PubMed1993

Activin receptor-like kinases: a novel subclass of cell-surface receptors with predicted serine/threonine kinase activity.

Human cDNA clones encoding four novel putative transmembrane protein serine/threonine kinases, denoted activin receptor-like kinase (ALK) -1, -2, -3 and -4, were obtained using a polymerase chain reaction (PCR)-based strategy. The PCR primers were designed based upon the sequence similarity between the activin receptor type II and Daf-1. The cDNA clones for ALK-1, -2 and -3 encode complete proteins of 503, 509 and 532 amino acids respectively. The ALK-4 cDNA is incomplete and the predicted protein of 383 amino acids has a truncated extracellular domain. The ALKs share similar domain structures, comprising predicted signal sequences at the N-terminals, followed by hydrophilic cysteine-rich ligand-binding domains, single hydrophobic transmembrane regions and C-terminal intracellular portions that consist almost entirely of putative serine/threonine kinase domains. The ALKs have approximately 40% sequence identity to activin receptors type II and IIB, transforming growth factor-beta (TGF-beta) type II receptor and Daf-1 in the kinase domains. However, the sequence identities are higher (60-79%) between ALK-1, -2, -3 and -4, suggesting that they form a subfamily among the putative receptor serine/threonine kinases. The extracellular domains of ALKs show only little sequence identity to other putative receptor serine/threonine kinases, but the cysteine residues are conserved. Their structural properties suggest that ALK-1 to -4 are receptors that may bind ligands that are members of the TGF-beta superfamily. The expression of mRNA in human tissues varied for the different ALKs; ALK-2 and ALK-4 showed ubiquitous tissue expression patterns, whereas the distribution of ALK-1 and ALK-3 varied strongly between different tissues with more restricted expression patterns. These results suggest that each ALK may have different in vivo functions.

Activin Receptors↗