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Biomedical subjects

T Doi

Publications and source records attributed to T Doi.

At least 415 records · Page 23Linked to original sources
PubMed1987

Transmembrane signaling of interleukin 2 receptor. Conformation and function of human interleukin 2 receptor (p55)/insulin receptor chimeric molecules.

Chimeric genes were constructed which gave rise to the expression of novel receptor molecules consisting of the extracellular domain of the human interleukin 2 receptor (IL-2-R; p55 or Tac antigen) joined to the transmembrane domain and either full-length or truncated cytoplasmic domain of the human insulin receptor (Ins-R). Expression studies using mouse T cell line EL-4 revealed that the chimeric receptors are able to manifest properties indistinguishable from the authentic IL-2-R. On the other hand, stimulation of the tyrosine kinase activity by IL-2 was not observed in the chimeric receptor with the entire cytoplasmic domain of the Ins-R. These findings thus shed light on the structural conformation and functioning of the IL-2-R complex.

Animals↗
PubMed1987

The in vivo stability, maturation and aminoacylation of anticodon-substituted Escherichia coli initiator methionine tRNAs.

We have constructed eight anticodon-modified Escherichia coli initiator methionine (fMet) tRNAs by insertion of synthetic ribotrinucleotides between two fragments ('half molecules') derived from the initiator tRNA. The trinucleotides, namely CAU (the normal anticodon), CAA, CAC, CAG, GAA, GAC, GAG and GAU, were joined to the 5' and 3' tRNA fragments with T4 RNA ligase. The strategy of reconstruction permitted the insertion of radioactive 32P label between nucleotides 36 and 37. tRNAs were microinjected into the cytoplasm of Xenopus laevis oocytes, and the following properties were evaluated: the stability of these eubacterial tRNA variants in the eukaryotic oocytes; the enzymatic modification of the adenosine at position 37 (3' adjacent to the anticodon) and aminoacylation of the chimeric tRNAs by endogenous oocyte aminoacyl-tRNA synthetases. In contrast to other variants, the two RNAs having CAU and GAU anticodons were stable and underwent quantitative modification at A-37. These results show that the enzyme responsible for the modification of A-37 to N-[N-(9-beta-D-ribofuranosylpurine-6-yl)carbamoyl]threonine (t6A) is present in the cytoplasm of oocytes and is very sensitive to the anticodon environment of the tRNA. Also, these same GAU and CAU anticodon-containing tRNAs are fully aminoacylated with the heterologous oocyte aminoacyl-tRNA synthetases in vivo. During the course of this work we developed a generally applicable assay for the aminoacylation of femtomole amounts of labelled tRNAs.

Animals↗
PubMed1987

Structure-function studies on bacteriorhodopsin. II. Improved expression of the bacterio-opsin gene in Escherichia coli.

The aims of this work have been to express bacterio-opsin with minimal variation from the native primary structure and to improve the level of expression in Escherichia coli. We describe the construction of plasmids in which the bacterio-opsin gene contains only an additional methionine residue at the N terminus and in which the C-terminal aspartic acid encoded in the gene has been deleted to conform to the mature protein. In attempts to improve bacterio-opsin expression, a variety of expression plasmids were constructed in which the promoters and the ribosome-binding sequences were varied. Invariably, in these plasmids, translation but not transcription of the bacterio-opsin gene was limiting. A striking increase in expression of the gene occurred when the codons for several of the N-terminal amino acids were changed to increase the A = T content. Bacterio-opsin expressed in E. coli was degraded with a half-life of 8-10 min. The addition of hydrophobic signal sequences at the N terminus increased the half-life and overall yield of the protein. Bacterio-opsin thus produced regenerated the native bacteriorhodopsin-like chromophore and carried out light-dependent proton translocation at a rate comparable to that of the native bacterio-opsin prepared from the purple membrane.

Amino Acid Sequence↗
PubMed1987

Spinal antinociceptive effects of adenosine compounds in mice.

The effects of injecting ATP, ADP, AMP, adenosine and adenine intrathecally on the pain response induced by the injection of substance P (10 ng/mouse) intrathecally were studied. All the compounds except adenine inhibited the pain response in a dose-related manner. The ED50 values of ATP, ADP, AMP and adenosine were 2.10, 0.93, 0.88 and 0.48 micrograms/mouse, respectively. Pretreatment with theophylline at a dose of 100 mg/kg p.o. markedly diminished all the antinociceptive effects. The effect of adenosine was not affected by s.c. injection of naloxone. These results suggest the existence of adenosine receptors which modulate spinal nociceptive sensory processing, independently of the endogenous opiate system.

Adenine Nucleotides↗
PubMed1987

Functional interleukin 2 receptors on B cells lacking Tac antigens.

Human B lymphoblastoid line, SKW 6-4, cells were induced to IgM-secreting cells by high concentrations of interleukin 2 (IL 2). These cells were found to be unreactive with anti-Tac antibody and did not express mRNA detectable for Tac antigen. In Scatchard plot analysis, low-affinity IL 2-binding sites were found on SKW 6-4 cells. Moreover, analysis of the IL 2-binding molecules revealed ones (molecular weight 70,000 and 75,000) distinct from Tac antigen. It is conceivable that IL 2 exerts its effect through its interaction with these novel IL 2-binding molecules in SKW 6-4 cells.

Antigens, Surface↗
PubMed1987

Lymphokine mediated production of an epidermal cell proliferation factor by cultured murine bone marrow cells.

The effect of cultured bone marrow cell supernatant (BMS) was studied on the proliferative response of cells of the transformed murine epidermal cell line Pam 212. Elevated DNA synthesis was found in Pam 212 cells cultured with BMS from bone marrow cells grown in spleen cell conditioned medium with concanavalin A (ConA). Pam cell proliferative activity was related to the histamine content in the culture supernatant. Neither spleen cell conditioned medium with IL1, IL2, or IL3 activity, nor ConA alone, showed any effect on Pam cell growth. A soluble mediator from the cultured bone marrow cells with mast cell characteristics was thought to be responsible for the stimulation of Pam cell growth, and Con A appeared to be a prerequisite for generation of this factor by the bone marrow cells.

Animals↗
PubMed1987

Placental-site trophoblastic tumor of the uterus. Clinicopathological and immunohistochemical observations of a case.

The clinicopathological features of a 28-year-old woman with placental-site trophoblastic tumor (PSTT) are described. The patient presented with severe proteinuria and was found to have a cystic uterine tumor. The serum beta-human chorionic gonadotropin (hCG) level was only slightly elevated. The tumor extended to the serosa without gross metastasis, and was resected. The specimen was composed of active intermediate trophoblasts (IT) and degenerative or inactive ITs. The former component had round to oval and vesicular nuclei, and abundant amphophilic or lightly eosinophilic cytoplasm. The latter component had irregular-shaped pyknotic nuclei and deeply eosinophilic cytoplasm. However, the tumor lacked the bilaminar (cyto- and syncytiotrophoblastic) structure that is a characteristic feature of choriocarcinoma. Immunohistochemical evaluation with human placental lactogen (hPL) and hCG antisera revealed that most of the tumor cells contained abundant hPL, whereas only a small number of cells contained hCG. This method seemed to be most helpful for the differential diagnosis of PSTT from other trophoblastic tumors or non-trophoblastic uterine tumors, and also to be useful for determining the prognostic behavior of PSTT.

Adult↗
PubMed1987

Structure of the rat platelet factor 4 gene: a marker for megakaryocyte differentiation.

A rat platelet factor 4 (PF4) cDNA has been isolated by immunoscreening a g lambda 11 rat megakaryocyte cDNA expression library. Sequence analysis of the rat PF4 cDNA revealed that this megakaryocyte protein is composed of a leader sequence of 29 amino acid residues and a mature protein sequence of 76 amino acid residues. The structure of rat PF4 derived from its cDNA shows a marked homology with the amino acid sequence of human PF4 obtained by classical protein chemistry techniques. This observation is particularly striking with regard to the carboxy-terminal region of rat and human PF4, where 28 of the last 31 C-terminal residues are identical. The rat PF4 gene was obtained from a rat genomic library by using rat PF4 cDNA as a hybridization probe. Sequence analysis showed that the gene is constructed of three exons and two short introns. The transcriptional start site is located 73 base pairs upstream of the translational start codon as judged by S1 nuclease mapping and primer extension. The 5' noncoding region of the gene also exhibited a sequence homologous to the TATA box at -31, as well as a series of direct and inverted repeat sequences and a cluster of 26 T residues at -155 to -218. This latter domain may be involved in regulating PF4 gene expression during megakaryocytopoiesis.

Animals↗
PubMed1987

Bilateral middle cranial fossa arachnoid cysts.

A rare case of bilateral arachnoid cysts of the middle cranial fossa in a child successfully treated by partial excision of their walls is reported. Patients with bilateral arachnoid cysts are usually severely disabled, presumably due to primary dysgenesis of the operculum; however, in our case no primary dysgenesis was noted and the operative result was excellent.

Arachnoid↗
PubMed1987

Clinicopathological study of patients with mesangial isolated C3d deposition in various glomerular diseases.

The clinicopathological findings of isolated mesangial C3d deposition in the absence of other complement components or immunoglobulins are summarized. 55 out of 242 individual human renal biopsies examined by immunoperoxidase microscopy had isolated C3d deposition. This group consisted of 12 patients with chronic glomerulonephritis, 8 with minimal-change nephrotic syndrome, 32 with benign recurrent hematuria, 2 with Bartter's syndrome and 1 with Raynaud's syndrome. None of these patients had a disorder of the renal function and in all the patients the disease took a benign clinical course. Light-microscopic findings indicated injuries ranging from minor glomerular abnormality to mild diffuse mesangial proliferative glomerulonephritis, and there were no other remarkable findings such as cellular crescents, global sclerosis or interstitial infiltration. By immunoperoxidase microscopy, fine granular deposits of C3d were identified only in the mesangium, and arteriolar C3 staining was seen in 31 of the 55 patients. In 38 of the 42 patients examined by electron microscopy, electron-dense deposits were identified in the mesangial matrix. These findings suggest that isolated C3d deposition is a new entity with benign features both clinically and pathologically.

Adolescent↗
PubMed1987

[Clinical observations on urethritis over the last eight years in Gifu City Hospital].

Clinical observations were made on patients with urethritis, syphilis, chancroid, genital herpes and venereal warts for the last eight years at Gifu City Hospital. The patients with urethritis, genital herpes and venereal warts tended to increase yearly, and the number of the cases with urethritis increased about 2.5 times in the eight years. Slightly more patients had nongonococcal urethritis than gonococcal urethritis excluding 1981. Of the patients with gonococcal urethritis seen between 1977 and 1979, 58% were treated with benzylpenicillin intramuscularly, and 43% of the patients seen between 1980 and 1984 were treated with a concomitant therapy of spectinomycin intramuscularly and minocycline or doxycycline orally. The cure rate for each treatment was 94% and 97%, respectively. Of the patients with nongonococcal urethritis seen between 1980 and 1984, 89% were treated with minocycline or doxycycline orally, and the cure rate was 97%. On the other hand, the cure rate was 43% for the treatment between 1977 and 1979, only 10% of whom had received treatment with minocycline or doxycycline.

Adolescent↗