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Biomedical subjects

H Kodama

Publications and source records attributed to H Kodama.

At least 577 records · Page 32Linked to original sources
PubMed1984

In vitro hemopoiesis within a microenvironment created by MC3T3-G2/PA6 preadipocytes.

The clonal preadipose cell line, MC3T3-G2/PA6, has the capacity to differentiate into adipocytes in response to glucocorticoids and to support in vitro growth of hemopoietic stem cells (CFU-S). To study the relationship between these capacities, we precultured the MC3T3-G2/PA6 cells for varying days in the presence or absence of dexamethasone and then cocultured them with mouse bone marrow cells. Logarithmically growing cultures contained no detectable adipocytes and showed the highest growth-supporting activity for CFU-S, whereas cultures containing the largest number of adipocytes showed the lowest activity. When bone marrow cells were seeded onto 3-day-old MC3T3-G2/PA6 preadipocyte layers at 1 X 10(5) cells/35-mm dish, day 12 CFU-S grew with a population doubling time of about 37 hr, and at least 75% of them were associated with the cell layer between days 2 and 7. In the absence of the preadipocytes, CFU-S were not detected in the adherent cell fraction and decreased with a half-life of about 18 hr. More than 80% of CFU-C were also found to be associated with the preadipocyte layer, and they increased about 24-fold in number during 7 days in culture. Morphologically, hemopoietic cells developing into mature granulocytes and macrophages were distributed between the layers of preadipocytes. Dendritic processes of preadipocytes were frequently in close alignment with the hemopoietic cells. However, adipocytes failed to show such an intimate association with hemopoietic cells. These results indicate that MC3T3-G2/PA6 cells in the preadipocyte stage, but not in the adipocyte stage, have the capacity to support CFU-S growth, and that hemopoiesis in our cocultivation system proceed within the microenvironmental milieu provided by MC3T3-G2/PA6 preadipocytes.

Adipose Tissue↗
PubMed1984

Antitumor and therapeutic effects of spleen cells from tumor-bearing mice cultured with T cell growth factor and soluble tumor extract.

Spleen cells of BALB/c mice that had been inoculated with syngeneic plasmacytoma MOPC 104E were cultured for 11 days in T-cell growth factor (TCGF) and ultrasonicated tumor extract (USE). Cultured lymphocytes (MOPC-CL) possessed three-fold more lytic units than normal spleen cells cultured in TCGF without USE (N-CL). Moreover, the in vivo neutralization assay suggested that MOPC-CL were composed of at least two populations, one possessing tumor-specific and the other nonspecific antitumor activity. When 2 X 10(7) of MOPC-CL were administered IP to mice that had been inoculated IP with 10(5) MOPC 104E cells 5 days previously marginal prolongation of survival was observed. This effect was not augmented by the single injection of a larger number (5 X 10(7] of CL, but was augmented by the repeated daily administration for 4 days (from day 5 to day 8 after the inoculation) of the same total number (5 X 10(7] of CL. In addition, IP injection of the streptococcal preparation OK432 before the transfer of CL significantly enhanced the therapeutic efficacy, and resulted in a cure rate of 20%. The mechanism of this combined effect appears to involve the effect of OK432 on interleukin 2 (IL-2) regulation systems in vivo. Our culture system with TCGF and USE and our therapy system with OK432 and CL allow the clinical application of adoptive immunotherapy for the many types of solid cancers.

Animals↗
PubMed1984

Suppression of natural cytotoxic activity of lymphocytes from cattle and sheep during the progress of bovine leukosis.

Peripheral blood lymphocytes (PBL) from cattle and sheep exhibited natural cytotoxicity on a fetal lamb kidney (FLK) cell line that was persistently infected with bovine leukemia virus (BLV) by 20-h 51Cr release assay. This cytotoxic activity was tested using PBL from normal cattle and sheep or BLV-infected animals. Although cytotoxic activity was also found in PBL from normal animals and from BLV-infected, but clinically healthy animals, the activity in PBL from animals with persistent lymphocytosis or leukemic animals was markedly decreased. The cytotoxic activity of PBL from 3 sheep sequentially tested before and during the disease was found to decrease gradually with the progress of the disease, and finally no cytotoxic activity was found at the time of death due to leukemia. These results suggest that the natural cytotoxic activity in PBL may have a role in immunosurveillance for progress of the tumor.

Animals↗
PubMed1984

Ecology of non-O 1 Vibrio cholerae in Toyama Prefecture.

The ecology of non-O 1 Vibrio cholerae and Vibrio mimicus as causes of cholera-like diarrhea or seafood-associated gastroenteritis has been investigated in Toyama Prefecture since 1980. The relationship between biological or serological characteristics of the isolates and their enteropathogenicity is discussed. Overall isolation rates from river water, sea water, and fish were 24.0, 59.5, and 33.7%, respectively, the isolation frequency being, in general, extremely high in the summer season, although the organisms were detected all year around in the case of sea water. Most isolates from river water were unable to grow on plates of TCBS agar to which colistin was added at a concentration of 1 microgram/ml (CL-TCBS). These strains quickly fermented cellobiose. O-51 and O-70 were the two most frequently detected serogroups among them and they did not show enteropathogenicity in the rabbit ileal loop ( RIL ) test. On the other hand, almost all isolates from sea water and fish as well as those from human diarrhea cases were able to grow on CL-TCBS, but were unable to ferment cellobiose quickly. O-36, O-10, O-6, O-8, O-39, and O-26 were the dominant serogroups of these isolates, and some of them showed enteropathogenicity in the RIL test. Six out of 98 isolates from river water, 14 out of 116 from sea water, and 19 out of 112 from fish were classified as Vibrio mimicus . All of these strains were able to grow on CL-TCBS and quickly fermented mannose but not cellobiose. O-41 was the most common serogroup among them and some of these strains showed enteropathogenicity in the RIL test. Production of a cholera-like enterotoxin among the isolates in Toyama Prefecture, if any, seemed to be poor.

Animals↗
PubMed1984

Studies on the enteropathogenic mechanism of non-O 1 Vibrio cholerae isolated from the environment and fish in Toyama Prefecture.

Enteropathogenic mechanisms of non-O 1 Vibrio cholerae were investigated using strains from the environment and those from fish in Toyama Prefecture. None of the 93 non-O 1 V. cholerae strains produced a detectable level of choleratoxin-like-enterotoxin (CT-like-enterotoxin) in Syncase medium, while 23 strains showed a distinct fluid accumulation in the rabbit ileal loop test (RIL). These RIL-positive strains neither produced CT-like-enterotoxin in vitro in the other four kinds of media which are considered suitable for CT production, nor in vivo in the ligated ileal loop. Approximately one-third of RIL-positive strains produced a fluid accumulating factor (FAF) which was not neutralized with anti-CT serum. FAF of a representative strain (Strain 79-9-2) was inactivated by heating at 100 C for 10 min, and has a molecular weight within the range of 50,000 to 100,000 daltons. Most accumulated fluids in RIL after inoculation with whole cultures of RIL-positive strains contained both hemolytic and cytotoxic principles. Desquamation of epithelial cells, inflammatory edema, neutrophile infiltration, loss of goblet cells and frequent hemorrhages were observed in sections of ligated ileal loop inoculated with whole cultures or concentrated culture filtrates of CT-like-enterotoxin-negative but RIL-positive strains. In contrast, neither desquamation of epithelial cells nor hemorrhage was observed in sections after inoculation with those of a CT-like-enterotoxin positive strain (Strain E 8498). These results indicated that most RIL-positive non-O 1 V. cholerae strains from the environment and fish isolated in Toyama Prefecture produce little CT-like-enterotoxin, but some of them produce FAF with cytotoxic activities.

Animals↗
PubMed1984

Noradrenergic modulation of human pancreatic growth hormone-releasing factor (hpGHRF1-44)-induced growth hormone release in conscious male rabbits: involvement of endogenous somatostatin.

To clarify the role of noradrenergic neurons in the regulation of GH secretion, the effects of iv administered noradrenergic antagonists were investigated in freely moving, conscious male rabbits. During a 6-h observation period (1030-1630 h), control rabbits manifested pulsatile GH secretion with surges between 1030-1200 and 1415-1630 h. Phenoxybenzamine, (POB), an alpha-adrenergic blocker (5 mg/kg, twice), abolished the episodic GH surges; propranolol, a beta-adrenergic blocker (2.5 mg/kg, twice), did not. The bolus injection (1 or 10 micrograms) of synthetic human pancreatic GH-releasing factor (hpGHRF) with 44 amino acid residues (hpGHRF1-44) resulted in significant rises in the plasma GH of control animals. The plasma GH responses to hpGHRF1-44 were significantly larger in propranolol-treated than control rabbits. In contrast, POB completely suppressed the hpGHRF1-44-induced GH release. The injection of antisomatostatin (SRIF) serum into POB-treated rabbits did not yield a disinhibition of the episodic GH surges but restored the plasma GH rises after hpGHRF1-44 injection. These results indicate that noradrenaline++ plays an important role in regulating GH secretion in the rabbit. We propose that alpha-noradrenergic blockade suppresses GH release not only by inhibiting the release of hypothalamic GHRF but also by stimulating the secretion of SRIF and that beta-noradrenergic blockade enhances GH release by inhibiting the release of SRIF from the hypothalamus.

Animals↗
PubMed1984

Stimulation of growth hormone by vasoactive intestinal polypeptide in acromegaly.

Vasoactive intestinal polypeptide (VIP) was administered as an iv bolus of 1 micrograms/kg BW to 8 acromegalic patients and in doses of 0.5 and 1 microgram/kg BW to 15 normal volunteers. Both systolic and diastolic blood pressures decreased, and pulse rate increased transiently after VIP injection. VIP stimulated PRL release from the anterior pituitary in normal subjects. Plasma PRL responses to VIP in women were dose dependent and larger than those in men. On the other hand, plasma GH levels rose markedly after VIP injection in all 6 patients with untreated acromegaly. In 2 patients studied after transsphenoidal microadenomectomy, there was no plasma GH response to VIP. In 2 other patients with inactive acromegaly as well as in normal subjects, VIP failed to affect plasma GH levels. In all 6 patients with active acromegaly, LRH (1-2 micrograms/kg BW, iv) did not increase plasma GH levels, but TRH (5-10 micrograms/kg BW, iv) caused significant increases in plasma GH, the magnitude of which was not similar to that of increases seen after VIP injection. Paradoxical GH responses to TRH were not observed in patients in the inactive phase after transsphenoidal surgery. These findings suggest that VIP stimulates GH release in vivo in acromegalic patients. A VIP test as well as a TRH test offer promise as simple and reliable techniques to evaluate the activity of acromegaly, particularly after transsphenoidal surgery.

Acromegaly↗
PubMed1984

Prolactin secretion from human prolactinomas perifused in vitro: effect of TRH, prostaglandin E1, theophylline, dopamine and dopamine receptor blockers.

To clarify the functional characteristics of prolactin (Prl)-producing adenoma cells, the effect of TRH, prostaglandin E1 (PGE1), theophylline, dopamine and dopaminergic antagonists on Prl secretion was examined in vitro in perifused pituitary adenoma tissues obtained at surgery from 8 patients with prolactinoma. Perifusion with TRH at a concentration of 10(-6) to 10(-5) M resulted in a significant increase in effluent Prl levels in 3 of the 8 adenoma tissues. In the remaining 5 adenomas, TRH produced no effect on Prl release in vitro. On the other hand, PGE1 (10(-5) M) stimulated Prl secretion in 2 of the 4 adenomas examined. Addition of theophylline (5.5 mM) caused a marked increase of effluent Prl levels in all 8 prolactinomas regardless of the reactivity to TRH or PGE1. Dopamine (5 X 10(-7) M) suppressed Prl secretion from adenoma tissue in 5 of 7 patients tested but had no effect in the remaining two adenomas. When perifused simultaneously with dopamine, sulpiride (D2-selective dopamine receptor blocker, 5 X 10(-7) M) blocked the inhibitory effect of dopamine on Prl release in 3 of the 4 dopamine-sensitive prolactinomas. In one adenoma responsive to dopamine but resistant to sulpiride, YM-09151-2 (relatively specific D1-dopamine receptor blocker, 5 X 10(-7) M) antagonized the dopaminergic inhibition of Prl release. When perifused alone, neither sulpiride nor YM-09151-2 affected Prl release from any of the adenoma tissues tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

In vitro and in vivo detection of infectious pancreatic necrosis virus in fish by enzyme-linked immunosorbent assay.

A double antibody enzyme-linked immunosorbent assay (ELISA) was used to detect infectious pancreatic necrosis virus (IPNV). The ELISA detected VR299 strain of IPNV at a dose of 10 to 20 ng of purified IPNV protein or 10(4) TCID50 in tissue culture fluid. Specificity of ELISA was demonstrated by an ELISA inhibition test. The ELISA did not detect infectious hematopoietic necrosis virus. Normal cell culture fluid and virus-non-inoculated rainbow trout (Salmo gairdneri Richardson) homogenate did not react in the test system. The IPNV was detected in rainbow trout fry inoculated with IPNV. Although infective virus titer in fish decreased rapidly 1 week after inoculation, IPNV antigen was detected by ELISA for 15 days. The IPNV antigen was detected in the fish tissue after inactivation of infective virus. The ELISA is a rapid and reliable method for the diagnosis of IPNV infection.

Animals↗
PubMed1984

Extracellular virulence factors of fish Vibrio: relationships between toxic material, hemolysin, and proteolytic enzyme.

Biological activities of cell-free culture filtrate of 3 virulent strains of fish Vibrio were examined to determine the relationship to the pathogenesis of fish vibriosis. Among the 3 strains examined, V anguillarum strains NCMB6 and NCMB571 produced hemolysin and protease, whereas V ordalii strain N7802 did not. Culture filtrate of strain NCMB571 were lethal to rainbow trout and produced a cytotoxic effect on fish cell line. Results revealed that the extracellular products may be involved in the pathogenesis of fish vibriosis.

Animals↗