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Biomedical subjects

T Ichikawa

Publications and source records attributed to T Ichikawa.

At least 469 records · Page 26Linked to original sources
PubMed1990

Roles of CD4+ and CD8+ cells in islet allo- and xeno-graft rejection.

We investigated the requirement for and the roles of CD8+ cells and CD4+ cells for islet graft rejection in allogeneic and xenogeneic combinations by in vivo administration of anti-Lyt2 monoclonal antibody (mAb), anti-L3T4 mAb or both to the recipient mice. In BALB/c to B6 (H-2 and non-H-2 incompatible combination), administration of anti-Lyt-2.2(CD8) or anti-L3T4(CD4) mAb resulted in rejection of most of the grafts, although their survival was prolonged significantly. Administration of both mAbs together completely blocked rejection and all allografts survived over 100 days with mAb administration. In B10.A(5R) to B10.A (H-2K and IA incompatible combination) or B10.AQR to B10.A (H-2K incompatible combination), administration of either mAb alone induced indefinite allograft survival. In bm12 to B6 (IA incompatible combination), allografts were not rejected even in nontreated recipients. In rat-to-mouse combinations, administration of anti-L3T4 mAb produced marked prolongation of graft survival and 3 out of 8 survived over 100 days. Administration of both mAbs also led to prolongation of graft survival which was similar to or better than that of anti-L3T4 mAb alone. The present results indicated that CD4+ and CD8+ cells participate in all types of islet graft rejection studied here and that the absolute requirements of CD4+ or CD8+ T cell subsets for islet rejection depend on genetic as well as species disparity.

Animals↗
PubMed1990

Recognition by restriction endodeoxyribonuclease EcoRI of octadeoxyribonucleotides containing modified sugar and base moieties.

The modified base and sugar moieties, 8-oxo-7,8-dihydroadenine (HO8A),8-methoxyadenine (MeO8A),8-methoxyguanine (MeO8G) and 9-[(2-hydroxy-1-(hydroxymethyl)-ethoxy)-methyl]-adenine (acA), were chemically introduced in place of the adenine or guanine in the octa-deoxyribonucleotides [d(GGAATTCC)] containing recognition sequence of Eco RI. to the regular DNA-fragment.

Carbohydrates↗
PubMed1990

[Pharmacokinetic, bacteriological and clinical studies on aztreonam in neonates].

Pharmacokinetic, bacteriological and clinical studies on aztreonam (AZT) were performed in neonates. The results obtained are summarized as follows. 1. Plasma levels and urinary excretion of AZT were determined in 18 neonates with ages between 1 and 30 days (gestation periods were 36 to 40 weeks and birth weights were 1,890 to 4,300 g) and in 2 infants with 54 and 60 days of age (gestation periods were 36 and 40 weeks, and birth weights were 2,300 and 3,300 g, respectively) upon one-shot intravenous injection of AZT 10 mg/kg (7 cases) or 20 mg/kg (11 cases) to the 18 neonates and 20 mg/kg to the 2 infants. Ampicillin (ABPC) 25 mg/kg was simultaneously injected to 5 cases of the neonates given AZT 20 mg/kg by one-shot intravenous injection and plasma concentrations of ABPC in these 5 cases were also studied. Plasma concentrations in neonates at 0.5 hour after intravenous injection of AZT 10 mg/kg were 11.5 to 27.6 micrograms/ml (average 20.3 +/- 5.5 micrograms/ml) and decreased with half-lives of 2.72 to 5.70 hours (average 3.81 +/- 1.28 hours), and the plasma levels at 8 hours after administration were 3.3 to 8.7 micrograms/ml (average 5.8 +/- 2.5 micrograms/ml). In the cases given AZT at 20 mg/kg, plasma levels at 0.5 hour were 12.4 to 48.8 micrograms/ml (average 35.9 +/- 11.6 micrograms/ml) and decreased with half-lives of 1.69 to 4.14 hours (average 2.94 +/- 0.76 hours) and AZT levels at 8 hours were 1.1 to 10.6 micrograms/ml (average 5.6 +/- 3.6 micrograms/ml). Urinary recovery rates in the first 8 hours after intravenous injection of the 10 mg/kg group were 15.5 to 61.9% (average 37.8 +/- 21.8%) and 16.3 to 62.2% (average 43.5 +/- 16.2%) for the 20 mg/kg group. Plasma concentrations in infants after administration of AZT 20 mg/kg were 33.0 to 35.6 micrograms/ml (average 34.3 +/- 1.8 micrograms/ml) at 0.5 hour and decreased with half-lives of 1.76 to 3.77 hours (average 2.77 +/- 1.42 hours) and AZT plasma levels at 8 hours were 1.4 to 5.8 micrograms/ml (average 3.6 +/- 3.1 micrograms/ml). Urinary recovery rates were 35.4 to 64.8% (average 50.1 +/- 20.8%). These results suggested that AZT shows a dose-dependent, high plasma concentration even in the neonatal period, as well as good urinary excretion from an early stage of the administration.(ABSTRACT TRUNCATED AT 400 WORDS)

Ampicillin↗
PubMed1990

[A primary malignant lymphoma of the appendix].

A malignant lymphoma (ML) of the gastrointestinal tract occurs most frequently in the stomach, and ML of the appendix is very rare, with only 16 cases reported in the Japanese literature. Reported is a case of a primary ML the appendix in a 48 year old male, in whom an ileocecal resection was carried out. This case was pathohistologically diagnosed as a diffuse large lymphoma of the B cell type, according to the LSG classification. Therapeutic problems were encountered because of the difficulty in making an early diagnosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Aberrant right gastric vein directly communicating with left portal vein system. Incidence and implications.

In 3 patients with primary hepatic malignancies, a communication between the right gastric vein and the left portal vein system was recognized at angiography. The right gastric vein entered directly into the left lateral portal veins in 2 patients and into the left medial portal veins in one. Portal angio-CT performed in one patient demonstrated a specific defect only in the left lateral superior area of the liver, consistent with the segmental opacification of the portal vein branch recognized on the angiogram. This rare communication was seen in 3 (1.5%) of 200 consecutive patients who underwent celiac angiography and is most likely an anomaly in which the right gastric vein directly enters the left portal vein instead of the portal vein trunk. When interpreting a filling defect not associated with a mass lesion on portal angio-CT for hepatic neoplasms or the right gastric vein communicating with the left portal vein system on the angiogram, this particular anomaly should be considered.

Adult↗
PubMed1990

Organization of choline acetyltransferase-containing structures in the cranial nerve motor nuclei and lamina IX of the cervical spinal cord of the rat.

The cholinergic structures in the cranial nerve motor nuclei and lamina IX of the cervical spinal cord of the rat were examined immunohistochemically with a monoclonal antibody to choline acetyltransferase (ChAT). The brainstem motor nuclei were classified into 3 groups according to the way of distribution of ChAT-positive structures in the neuropil of the nucleus. 1. The oculomotor, trochlear and abducent nuclei contained moderately ChAT-positive perikarya and dendrites. A small number of ChAT-positive bouton-like structures were found in the neuropil, but they were not in contact with ChAT-positive perikarya and dendrites. 2. Motoneurons in the facial, hypoglossal and trigeminal motor nuclei were moderately to strongly ChAT-positive. There were in the neuropil numerous ChAT-positive bouton-like structures and many of them were in contact with ChAT-positive perikarya and dendrites. The same pattern of organization of ChAT-positive structures was observed in lamina IX of the cervical spinal cord. In the nucleus ambiguus, the perikarya and proximal dendrites of about half population of motoneurons contacted with ChAT-positive bouton-like structures while the rest of motoneurons did not. ChAT-positive bouton-like structures in contact with motoneurons are interpreted as the cholinergic synaptic terminals, and this suggests that motoneurons in this group are cholinoceptive as well as cholinergic. 3. Neuronal perikarya and dendrites in the dorsal nucleus of the vagus showed weak to moderate positivity of ChAT. The neuropil of this nucleus was free from any distinctly ChAT-positive structures.

Animals↗
PubMed1989

Effects of gene dosage on the expression of human growth hormone cDNA in Escherichia coli.

Gene dosage effects on the foreign protein production in Escherichia coli have been analyzed with the expression vectors containing one, two and four tandemly arranged human growth hormone cDNAs under various culture conditions. In a limited synthetic culture medium, a proportional relationship was observed between the number of the integrated cDNA and the amount of human growth hormone produced. With a culture medium rich in the nutrients, however, no such relationship was observed. These results suggest that, under the limited culture conditions, high-level expression of a foreign gene can be achieved by tandemly joined multiple copies of cDNA.

Blotting, Western↗
PubMed1989

Extracellular recording of vestibulo-thalamic neurons projecting to the spinal cord in the cat.

Forty vestibulo-thalamic (VT) neurons were recorded extracellularly in the vestibular nuclei of the anesthetized cat. More than half of the VT neurons responded monosynaptically to vestibular nerve stimulation; the others responded polysynaptically. The VT neurons were activated antidromically from one or two sites in the contralateral VPL, VPM, VL, VM, SG, and PO in the thalamus. Their axonal arborizations in the thalamus were likely restricted in narrow areas. About three quarters of the VT neurons were also activated antidromically from the ventral funiculus in the C1 segment. Axonal branchings were found in the contralateral C1 gray matter. The VT neurons were mainly localized in the descending vestibular nucleus.

Animals↗
PubMed1989

Functional characterization of two cytochrome P-450s within the mouse, male-specific steroid 16 alpha-hydroxylase gene family: expression in mammalian cells and chimeric proteins.

Two cDNAs, pc16 alpha-2 and pc16 alpha-25, which encode P-450s from within the mouse, male-specific steroid 16 alpha-hydroxylase (C-P-450(16 alpha)) gene family, were transfected into COS-1 cells in order to study catalytic activities of the expressed P-450s. pc16 alpha-2 was shown previously to encode the growth hormone dependent and androgen-dependent C-P-450(16 alpha) in adult male mice (Wong et al., 1987). The sequence of pc16 alpha-25-encoded P-450 (P-450cb) was identical with gene cb within the C-P-450(16 alpha) family. There was 94% and 87% nucleotide and amino acid sequence identity, respectively, between P-450cb and C-P-450(16 alpha). We expressed both P-450s by transfecting their cDNAs into COS-1 cells and found that steroid 16 alpha-hydroxylase activity was catalyzed by C-P-450(16 alpha) but not by P-450cb. In addition to testosterone, progesterone and estradiol were hydroxylated specifically at the 16 alpha-position by the expressed C-P-450(16 alpha). The results indicated that a broad steroid substrate specificity with high regio- and stereoselectivity at that position was a characteristic of C-P-450(16 alpha). We constructed and expressed chimeras between the two P-450s and found that the presence of about two-thirds of the C-P-450(16 alpha) molecule from its C-terminus was necessary for the chimeric cytochrome to maintain steroid 16 alpha-hydroxylase activity.

Amino Acid Sequence↗
PubMed1989

Mouse steroid 15 alpha-hydroxylase gene family: identification of type II P-450(15)alpha as coumarin 7-hydroxylase.

We identified type II P-450(15)alpha as mouse coumarin 7-hydroxylase (P-450coh). Unlike type I P-450(15)alpha, the other member within the mouse steroid 15 alpha-hydroxylase gene family, type II catalyzed little steroid 15 alpha-hydroxylase activity, yet structurally there were only 11 substitutions between type I and type II P-450(15)alphaS within their 494 amino acid residues (Lindberg et al., 1989), and the N-terminal sequence (21 residues) of P-450coh was identical with that of both P-450(15)alphaS. Induction by pyrazole of coumarin 7-hydroxylase activity correlated well with the increase of type II P-450(15)alpha mRNA in 129/J male and female mice. Pyrazole, on the other hand, was less in males or not effective in females in inducing the 15 alpha-hydroxylase activity and type I P-450(15)alpha mRNA. Expression of type I and II in COS-1 cells revealed that the latter catalyzed coumarin 7-hydroxylase activity at 10 to approximately 14 pmol min-1 (mg of cellular protein)-1. The former, on the other hand, had a high testosterone 15 alpha-hydroxylase but little coumarin 7-hydroxylase activity. It was concluded, therefore, that type II P-450(15)alpha is the mouse coumarin 7-hydroxylase. Identification of type II as the P-450 specific to coumarin 7-hydroxylase activity and characterization of its cDNA and gene, therefore, were significant advances toward understanding the basis of genetic regulation of this activity in mice (known as Coh locus).

Animals↗
PubMed1989

The structure and characterization of type I P-450(15) alpha gene as major steroid 15 alpha-hydroxylase and its comparison with type II P-450(15) alpha gene.

The structures of genes 15 alpha OH-1 and 15 alpha OH-2, within the mouse steroid 15 alpha-hydroxylase (P-450(15) alpha) family were determined. Genes 15 alpha OH-1 and -2 encoded mouse Type I and II P-450(15) alpha, respectively (Squires, E.J., and Negishi, M. (1988) J. Biol. Chem. 263, 4166-4171). The two genes, which spanned approximately 8 kilobase pairs of total length, showed nearly identical structures and were divided into nine exons at the same positions. A high nucleotide sequence homology (greater than 96%) indicated that 15 alpha OH-1 and -2 were duplicated within 5 million years. The two major transcription start sites were located at 14 and 24 base pairs (bp) upstream from the initiation Met in both genes. No tissue-specific difference in 15 alpha OH-1 and -2 transcriptional start sites was found in mouse liver and kidney. Both 15 alpha OH-1 and -2 had TATA and CAAT boxes at 30 and 100 bp, respectively, upstream from their major transcription start sites. A glucocorticoid regulatory element was present at 336 bp upstream from the start site in both genes. In addition to these motifs, 15 alpha OH-2 had an SV40 enhancer core sequence immediately downstream from its CAAT box. There were only 11 substitutions between Type I and II P-450(15) alpha in their 494-amino acid residues. Type I cDNA-transfected cell homogenates had testosterone 15 alpha-hydroxylase activity at approximately 9 pmol/min/mg protein. Type I also catalyzed progesterone and androstenedione 15 alpha-hydroxylase activities. Type II, on the other hand, exhibited little activity toward these steroids. The results indicated that Type I was the major steroid 15 alpha-hydroxylase. The differential 15 alpha OH-1 expression, therefore, determined the sexual dimorphism of the tissue-specific 15 alpha-hydroxylase activity in mice.

Amino Acid Sequence↗
PubMed1989

Purification and characterization of cytochrome P-450 induced by benz(a)anthracene in mouse skin microsomes.

Topical application of benz(a)anthracene to mouse skin elicited a 2-fold increase in cytochrome P-450 content, with accompanying increases in monooxygenase activities such as benzo(a)pyrene hydroxylation, 7-ethoxycoumarin O-deethylation, and acetanilide 4-hydroxylation, in the microsomes. A major form of cytochrome P-450 was purified from skin microsomes of mice treated with polycyclic aromatic hydrocarbon. A specific content of 1.95 nmol/mg of protein, which corresponded to 48-fold purification from the microsomes, was observed. The purified protein produced a single major band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis having a molecular weight of 55,000. Using Western blotting, the band immunochemically cross-reacted with antibody which had been raised against rat liver cytochrome P-450MC-1. The purified preparation efficiently catalyzed benzo(a)pyrene hydroxylation and 7-ethoxycoumarin O-deethylation when reconstituted with NADPH-cytochrome P-450 reductase. These activities were inhibited by 7,8-benzoflavone as well as anti-cytochrome P-450MC-1 antibody, but not by P-450PB-1 antibody. The results indicate that, in mouse skin microsomes, a cytochrome P-450 induced by benz(a)anthracene is enzymatically and immunochemically similar to rat liver cytochrome P-450MC-1. It is suggested that this enzyme plays an important role in the activation of carcinogenic polycyclic aromatic hydrocarbons.

Animals↗
PubMed1989

Progression and selection in heterogeneous tumor composed of androgen-responsive Shionogi carcinoma 115 and its autonomous subline (Chiba subline 2).

Shionogi Carcinoma 115 (SC 115) is an androgen-dependent mouse tumor, and Chiba subline 2 (CS 2) is its androgen-independent subline which differs from SC 115 in cell size, amount of androgen receptors, and karyotype. To shed light on the mechanism of clonal selection of androgen-independent tumors, mixed tumors with SC 115 and CS 2 were prepared, and growth of these tumors was examined in vivo and in vitro. When the mixed tumor was transplanted in mice, CS 2 showed a predominant growth over SC 115. In a culture of mixed tumor cells, however, CS 2 showed no selective growth advantage. The suppressive interaction which occurred in vivo was due neither to transferable substances, nor to some immunological factor(s). It may be, at least partially, attributable to necrosis formation in SC 115, which developed with an increase in the size of the tumor.

Androgens↗
PubMed1989

Primary malignant lymphoma of the brain: demonstration of immunoglobulin gene rearrangements in four cases by the Southern blot hybridization technique.

Using the Southern blot hybridization technique, four cases of the primary malignant lymphomas of the brain, histologically diffuse large cell lymphoma, were examined for the immunoglobulin gene rearrangements. In three lymphomas, the rearrangements were observed in both heavy and light chain genes, providing strong evidence for a B cell lineage of these tumors. On the other hand, in the remaining lymphoma, the rearrangement was observed only in the heavy chain gene. Despite this, immunohistochemical examination revealed positive stainings for heavy and light chain immunoglobulins in tumor cells, suggesting the occurrence of light chain gene rearrangement at the undetectable level. Thus, B lymphocytic differentiation at the gene level was demonstrated in three, or possibly all, of the primary intracerebral malignant lymphomas examined. Since no more than two rearrangements were detected in each immunoglobulin gene, these lymphomas were considered to be monoclonal in nature.

Adult↗
PubMed1989

Predominant use of a particular alpha-chain in suppressor T cell hybridomas specific for keyhole limpet hemocyanin.

We isolated and sequenced the rearranged genomic variable (V) and joining (J) gene segments of T cell receptor alpha-chain gene from two independent keyhole limpet hemocyanin (KLH)-specific suppressor T cell (Ts) hybridomas (BW5147 x C57BL/6 KLH-Ts). These nucleotide sequences were compared with those of germline DNA from kidney and also with cDNA of alpha-chain (VJ alpha 281) previously isolated from Ts hybridoma (34S-281) with KLH/H-2b Ts activity. The entire V alpha and J alpha sequences of all three Ts hybridomas were exactly identical and were encoded by the germline V alpha and J alpha gene segments without any mutations, except for 2-nucleotide deletions from both the 3' end of V alpha and 5' end of J alpha gene segments, respectively, and a 1-nucleotide (guanine) insertion in the junctional (N) region which was not encoded by the germline gene. Six additional KLH-Ts hybridomas, further analyzed, also possessed the same alpha-chain, indicating the preferential usage of the particular alpha-chain in these hybridomas. As chromosome analysis demonstrated a different pattern in each clone, these hybridomas appear to be independent. More surprisingly, 0.5-1.5% of the total functional T cell alpha-chain mRNA in the thymus and spleen of unprimed C57BL/6 mice was found to be of this particular alpha-chain. These results suggest that the repertoire of KLH-Ts is strictly limited.

Amino Acid Sequence↗
PubMed1989

An adult case of psychogenic alopecia universalis.

A 39-year-old male with psychogenic alopecia universalis is reported to be a rare adult case. There are two characteristic features which are the reactive depressive state and hair loss on the head, eyebrows, axilla and genital organ. Discussions on the psychogenesis of these findings are as follows: The first is that the psychic escape from social life may be represented as the hair loss. And the second is that the depressive and anxious states as a result of his suffering from the initial alopecia areata which brought him changes in the physical image exaggerate the skin findings which lead to alopecia universalis.

Adult↗