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K Kikuchi

Publications and source records attributed to K Kikuchi.

At least 1,009 records · Page 56Linked to original sources
PubMed1988

Regulation of in vivo immunological reactions by monoclonal antibody against lymphocyte activation antigen.

In vivo effects of a monoclonal antibody that recognizes rat lymphocyte activation antigen were studied. Spleen cells obtained from sheep red blood cell (SRBC)-immunized rats developed strong PFC response against SRBC. However, the 5C6-F4 treatment resulted in the inhibition of subsequent development of PFC response. The suppression of PFC response was due to the inhibition of generation of helper T cells, but not due to the preferential induction of suppressor cells. In addition, 5C6-F4 antibody was also found to inhibit the clinical expression of collagen-induced rat arthritis and the synovial inflammation in collagen-induced arthritis rats. Furthermore, the in vivo generation of cytotoxic cells against syngeneic tumor cells was also inhibited by 5C6-F4 antibody. The in vivo administration of 5C6-F4 antibody did not cause any pathological changes in brain, lung, liver, kidney, spleen, thymus, and lymph nodes.

Animals↗
PubMed1988

The expression of tumor rejection antigen on rat fetus fibroblasts transformed by the ras oncogene.

The expression of tumor rejection antigens (TRA) was analyzed on clones of rat fetus-derived fibroblasts, WFB, transformed or transfected by oncogenes. It was shown that a tumorigenic W14 clone, which is an activated H-ras transformant of parental WFB, expressed TRA in transplantation experiments using syngeneic WKA rats. The data also showed that W14 TRA was acquired in the event of cell transformation, since it was not detected on parental non-transformed WFB cells or Wmyc-4 clone which is a transfectant of WFB by mouse plasmacytoma-derived c-myc DNA. However, TRA was not expressed or at least was not detected on highly tumorigenic W31, another clone of H-ras transformants of parental WFB, in the transplantation experiments. We also assessed the level of expression of major histocompatibility antigens (MHC) class I molecules on these cells by using R4-8B1 Mab that reacts specifically with rat class I antigen. The data indicated that it was decreased on W14, W31, and Wmyc-4, but not on parental WFB. Although this molecule was weakly positive on W14 cells, W31 and Wmyc-4 showed even greater decreases. These data may indicate that the TRA expression and its recognition by syngeneic hosts are dependent upon the transformed clones, although their parental cell is the same. We discuss in detail this difference of expression and recognition of TRA in the context of the cell transforming process.

Animals↗
PubMed1988

Two distinct mechanisms involved in the infiltration of lymphocytes into tumors.

We have analyzed the mechanism controlling the infiltration of lymphocytes into tumor tissues. W3/25 (+) (helper/inducer phenotype) T cells obtained from tumor tissues of T-9 sensitized rats produced soluble factors. We demonstrated that the soluble factors were responsible for the infiltration of T lymphocytes into tumor tissues by using a modified Boyden chamber technique. We established a system in which we stained filters of the Boyden chamber by an immunoperoxidase technique, thus directly determining the phenotype of cells that had actually migrated into the filters in response to the soluble factors. Upon fractionation of soluble factors produced by W3/25 (+) T cells, four peaks of lymphocyte migration factor (LMF) activity were detected. Peaks B and C exhibited strong LMF activity and specifically attracted R1-10B5 (+) (suppressor/killer phenotype) T cells. Thus, the infiltration of R1-10B5 (+) T cells into tumor tissues was partly explained by LMF produced by tumor-infiltrating W3/25 (+) T cells. The expression of a putative receptor for LMF by lymphocytes may also influence the degree of lymphocyte infiltration into tumors.

Animals↗
PubMed1988

Plasma atrial natriuretic polypeptide concentration in healthy children from birth to adolescence.

We measured plasma atrial natriuretic polypeptide concentrations in the umbilical artery and vein, and peripheral veins of healthy children from birth to adolescence to establish the normal range. The plasma atrial natriuretic polypeptide concentration in the umbilical artery (mean +/- SD, 51.0 +/- 21.4 fmol/ml) was significantly higher than that in the umbilical vein (18.1 +/- 13.5 fmol/ml) in neonates after vaginal delivery. Also neonates aged 5 days or less had a significantly high concentration in the peripheral vein (60.7 +/- 29.4 fmol/ml). There was no significant difference in atrial natriuretic polypeptide concentrations in the peripheral veins between older children and adults. The concentrations in children aged more than 5 days and adults aged 20-34 years were 14.4 +/- 7.4 fmol/ml and 10.0 +/- 4.8 fmol/ml, respectively. However, the atrial natriuretic polypeptide concentration in the umbilical artery was not increased in three neonates delivered by caesarean section although they had a high concentration in the peripheral vein 24 hours after birth.

Adolescent↗
PubMed1988

Taurine transport by rat intestine.

Rat intestinal transport of taurine was studied using jejunal brushborder membrane vesicles and everted jejunal sacs. Membrane vesicle experiments showed that the initial rate (at 10 s) of 10 microM taurine uptake was stimulated 3.5-fold by an inwardly directed Na+ gradient when compared with a K+ gradient. The Cl- salt of Na+ supported uptake to a significantly greater degree than did more (SCN-) or less (SO2-4) permeant salts. Na+-stimulated uptake at 1 min achieved a value 2.5 times greater than equilibrium ("overshoot"). When 10 s taurine uptake was determined over a range of taurine concentrations (10-1,000 microM) and plotted using the Woolf-Hofstee equation, a diffusive and carrier-mediated component was apparent. Half-maximal, carrier-mediated uptake occurred at 25 +/- 9 microM taurine (Km). An inside-negative, valinomycin-induced K+ diffusion potential stimulated 10-s taurine uptake when compared with voltage-clamped conditions (4.9 vs. 2.6 pmol/mg protein; P less than 0.05). Incubation with a structural analogue, hypotaurine, reduced 10-s taurine uptake by 89%. Uptake by everted jejunal sacs also demonstrated Na+ stimulation and inhibition by hypotaurine. These data confirm the existence of a high-affinity rat jejunal brush-border membrane-associated taurine transport mechanism that is electrogenic, stimulated by a Na+ gradient, and modified by external Cl-.

Animals↗
PubMed1988

Characterization of calcium transport by basolateral membrane vesicles of human small intestine.

The present studies investigated the mechanism of Ca2+ transport across basolateral membrane vesicles (BLMVs) prepared from human small intestine. Ca2+ uptake represented transport into the intravesicular space as evident by osmolality study and by the demonstration of Ca2+ efflux from the intravesicular space by Ca2+ ionophore A23187. Ca2+ uptake was stimulated by Mg2+-ATP. Kinetic parameters for ATP-dependent Ca2+ uptake revealed a Michaelis constant (Km) of 0.02 +/- 0.01 microM and a maximum rate of uptake (Vmax) of 1.00 +/- 0.03 nmol.mg protein-1.min-1.Ca2+ uptake in the absence of Mg2+ was inhibited by 75%. The Km of ATP concentration required for half-maximal Ca2+ uptake was 0.50 +/- 0.1 mM. Calmodulin (10 micrograms/ml) increased Vmax to 1.62 +/- 0.02 nmol.mg protein-1.min-1 (P less than 0.001). Km values were 0.017 +/- 0.001 microM, which was not significantly different from control values. Basolateral membranes depleted of calmodulin by EDTA osmotic shock decreased ATP-dependent Ca2+ uptake by 65%. Trifluoperazine, an anticalmodulin drug, inhibited ATP-dependent Ca2+ uptake by 50%, while no inhibition was noted in calmodulin-depleted membranes. Efflux of Ca2+ in the BLMVs was stimulated by trans-Na+. Na+-dependent Ca2+ uptake was saturable with respect to Ca2+ concentration and exhibited a Km of 0.09 +/- 0.03 microM and a Vmax of 1.08 +/- 0.01 nmol.mg protein-1.min-1. These results are consistent with the existence of a Na+-Ca2+ exchange system and ATP and Mg2+-dependent, calmodulin-regulated Ca2+, transport mechanism in BLMVs of human enterocytes.

Adenosine Triphosphate↗
PubMed1988

Insulin resistance in a boy with congenital generalized lipodystrophy.

We have studied insulin resistance in a 12-year-old Japanese boy who presented with congenital generalized lipodystrophy. Oral glucose tolerance test exhibited a diabetic pattern with normal fasting plasma glucose. Results from euglycemic glucose clamp study showed decreases in both insulin sensitivity and responsiveness. Both the patient's erythrocytes and Epstein-Barr virus transformed lymphocytes showed low-normal insulin binding with a slight reduction in binding affinity in the latter. Insulin binding to the cultured fibroblasts was decreased due to a lowered affinity. In addition, they displayed a rightward shift of the insulin dose-response curve for D-14C-glucose uptake with no decrease in the maximum uptake. Insulin-stimulated autophosphorylation and kinase activity of the wheat germ agglutinin purified receptors from the Epstein-Barr virus-transformed lymphocytes appeared normal. The reason for some discrepancies in insulin binding among the cells remains unknown, and we cannot formulate a conclusion as to whether or not a primary binding defect of insulin receptors exists and contributes to insulin resistance in the patient. The decrease in insulin responsiveness demonstrated in the glucose clamp study may result from a defect at the rate-limiting step in the postbinding process of insulin action, presumably a defect in the glucose transport system in muscle tissues. The defect may be secondary to changes in in vivo circumstances.

Cell Line, Transformed↗
PubMed1988

Hypothalamic-pituitary function in growth hormone-deficient patients with pituitary stalk transection.

We compared 1.5 T magnetic resonance (MR) image findings with hypothalamic-pituitary function in 11 patients with idiopathic pituitary dwarfism, each of whom had a history of perinatal abnormalities, and 1 patient with posttraumatic pituitary dwarfism. MR imaging revealed transection of the pituitary stalk in all patients and the formation of an ectopic posterior lobe at the proximal stump in 9 patients, none of whom had polydipsia or polyuria. Three patients without an ectopic posterior lobe had diabetes insipidus. The 5 patients who had small pituitary glands (less than 2 mm in height) had hypothyroidism with low serum TSH concentrations and low serum cortisol responses to insulin-induced hypoglycemia; however, 7 patients with normal-sized pituitary glands had normal thyroid and adrenal function. The serum GH response to GHRH did not correlate with the size of the pituitary gland. The patients with small pituitary glands had delayed or prolonged serum TSH responses to TRH and impaired serum LH and FSH responses to GnRH; 4 of the patients with normal-sized pituitary glands had normal serum TSH, LH, and FSH responses. Only 2 patients had high basal serum PRL concentrations. The endocrinological data suggest that reestablishment of the hypothalamo-hypophyseal portal circulation, which cannot be seen by MR imaging, may occur. We suggest that the primary cause of idiopathic pituitary dwarfism in many patients is injury to the pituitary stalk at birth.

Adolescent↗
PubMed1988

Analysis of glucose-6-phosphate translocase and hexose-6-phosphate phosphohydrolase, the two obligatory components of microsomal glucose-6-phosphatase system, in rat liver.

A membrane filter procedure developed by Igarashi et al. (1984) for the measurement of glucose 6-phosphate uptake by the microsomes has been demonstrated to be a good method for assaying glucose-6-phosphate translocase, an obligatory component of the microsomal glucose-6-phosphatase system. When glucose-6-phosphate translocase was assayed in developing and diabetic rat livers independently of hexose-6-phosphate phosphohydrolase, another obligatory component of the glucose-6-phosphatase system, the two activities were found to undergo alterations, whose profiles, however, were quite distinct from each other. The profile of the microsomal glucose-6-phosphatase activity resembles the profile of the phosphohydrolase activity rather than that of the translocase activity, suggesting that the phosphohydrolase may be rate-limiting at least under these conditions. AH-109A, a strain of transplantable rat ascites hepatoma, was found to lack both glucose-6-phosphate translocase and hexose-6-phosphate phosphohydrolase activities.

Aging↗
PubMed1988

Indication of cryosurgery on tonsillar diseases.

The present studies are concerned with the reconfirmation of cryo-effects on the tonsil, such as advantages of cryosurgery on habitual tonsillitis, on expansive growth of tonsillar haemangioma and papilloma, and on malignant lymphoma. The present results revealed that post-operative healing of the wounds was satisfactory with minimum scar formation. Recurrence of habituere tonsillitis within three years after cryosurgery was 17%. Cryosensitivity was extremely high on patients with haemangioma and papilloma, even in cases of malignant lymphoma.

Adolescent↗