Search PubMed⌕ Search

Biomedical subjects

T Fujimoto

Publications and source records attributed to T Fujimoto.

At least 415 records · Page 23Linked to original sources
PubMed1991

Ectopic colonization of primordial germ cells in the chick embryo lacking the gonads.

Chick primordial germ cells (PGCs) first appear in the extraembryonic region in the early embryo, then temporarily circulate via the blood vascular system and finally migrate into the gonadal anlagen. In the present study, we examined the trend of ectopic distribution of PGCs in the chick embryo when its future gonadal region had been removed at an early stage. Embryos at stage 10, from which the caudal third region was excised, were incubated until they reached stages 14 to 20. In embryos at stage 14, about 80% of the total PGCs were found in the capillaries of the yolk sac, whereas others were observed in the head, mainly in the mesenchyme and small vessels close to the neural tube. From stage 18 onward, many PGCs accumulated in the embryo proper; about 90% of them colonized in the head region around the neural tube. These ectopic PGCs in the head were found in the capillaries, sometimes as thrombi or emerging from them into the adjacent mesenchyme. These results show that, when the chick embryo lacked gonads, the PGCs could be concentrated in the head region and migrated from the capillaries into the mesenchyme.

Animals↗
PubMed1991

A fine morphological study of germ cells in asymmetrically developing right and left ovaries of the chick.

Germ cells of the chick ovary which develop asymmetrically on the right and left sides of the embryo were observed by electron microscopy from 7 to 17 days of incubation. Germ cells showed different patterns in the right and left ovaries, and also differences in the cortex and in the medulla. At 7 to 9 days, germ cells were individually present in both the right and left ovaries. They proliferated from 10 days onward and formed many cell aggregates. In each aggregate, germ cells were joined by intercellular bridges, and their cell cycles were synchronized. Although meiotic features of the germ cells were frequently found in the cortex of the left ovaries at 16 days, some germ cells exhibited these features at earlier days. In the meiotic germ cells, the "Balbiani body," which was composed of a concentration of cell organelles shifted to one pole of the cell, was always seen. The appearance of a meiotic nucleus and Balbiani body was characteristic of germ cells located in the left ovarian cortex, whereas those were never seen in the left medulla and in the right ovary. At 16 and 17 days, some germ cells were released into the lacunae of the medulla of both the right and left ovaries. The meaning of this phenomenon is discussed. Degenerating germ cells were frequently observed in the right ovary, but rarely in the left.

Animals↗
PubMed1991

Glucagon-induced alteration of serum bile acid level in patients with liver cirrhosis.

Percent changes in serum total bile acid level after IV administration of 1 mg glucagon were measured in 61 cirrhotics. Thirty-three of 38 cases with Child's grade A disease showed a reduction of total bile acid level at 15 minutes; this level was maintained in the majority of them until 120 minutes. A similar mode of serial changes in total bile acid level was also shown in the cases with Child's grade B disease. On the other hand, only 2 of 10 cases with Child's grade C showed a reduction of total bile acid level at 15 minutes. Reduction of total bile acid level at 15 minutes after glucagon administration was mimicked by infusion of dibutyryl cyclic adenosine monophosphate. However, in 3 of 6 cases with elevated total bile acid level at 15 minutes after glucagon administration, dibutyryl cyclic adenosine monophosphate induced a reduction of total bile acid level. Also, it was confirmed that glucagon enhances the uptake of taurocholate into freshly isolated rat hepatocytes by activating Na(+)-dependent, carrier-mediated membrane transport system and observed that its effect is associated with elevation of Vmax (0.6114 nmol.min-1 x 10(6) cells-1 without glucagon; 0.975 nmol.min-1 x 10(6) cells-1 in glucagon added) but not with affecting Km (13.58 mumol/L without glucagon; 13.71 mumol/L with glucagon) or protein synthesis which is inhibited by cycloheximide. These observations suggest that glucagon enhances Na(+)-coupled membrane transport of bile acids in the liver and causes the reduction of serum total bile acid level and that a lack of this response may be indicative of membrane dysfunction in the liver.

Bile Acids and Salts↗
PubMed1991

Induction of anti-idiotypic T cells through a network mechanism.

BALB/c mouse T cells that recognized the idiotype expressed on M104E(mu, lambda 1) were induced by immunization with Dextran B-1355. T cells derived from mice immunized with 1 mg of Dextran B-1355 showed a marked proliferative response against M104E, whereas T cells from mice immunized with Ficoll or smaller amounts of Dextran B-1355 did not. BCL1Id, which had an identical isotype, did not induce proliferation of T cells. The T cell proliferative response against the idiotype on M104E required macrophages as antigen-presenting cells. The proliferative response was inhibited when antigen-presenting cells were treated with NH4Cl or chloroquine, which are antigen-processing inhibitors. These results indicate that anti-idiotypic T cells which recognized processed idiotopes could be induced physiologically through a network mechanism.

Animals↗
PubMed1991

Lysis of fresh human tumor cells by autologous peripheral blood lymphocytes and tumor-infiltrating lymphocytes activated by PSK.

The protein-bound polysaccharide PSK was tested for the ability to induce in vitro autologous tumor killing (ATK) activity in human cancer patients. Peripheral blood lymphocytes (PBL) and tumor-infiltrating lymphocytes (TIL) demonstrated various levels of cytotoxicity against autologous, freshly isolated tumor cells. When PBL and TIL were cultured overnight with PSK, ATK activity was induced in previously non-reactive cases and augmented in previously reactive samples. The PSK effect was observed with PSK concentrations of 10-100 micrograms/ml that could be obtained in the blood of cancer patients who received standard oral administration of PSK. The manifestation of PSK-induced ATK required active cell metabolism and RNA and protein syntheses, but not DNA synthesis of lymphocytes. PSK-induced enhancement of ATK was not abrogated by monoclonal antibodies (mAb) directed against interferon (IFN) alpha or IFN gamma. In addition, mAb that neutralized interleukin-2 (IL-2) or mAb reactive with alpha-chain or beta-chain of IL-2 receptors (IL-2R) had no effect on PSK-induced ATK activity. Supernatants from PSK-stimulated lymphocyte cultures did not induce ATK. Cell fractionation experiments revealed that CD3-CD16+ large granular lymphocytes (LGL) and/or CD3+CD16- T lymphocytes were responsible for both spontaneous and PSK-induced ATK. PSK-activated LGL, but not T lymphocytes expressed lysis of fresh allogeneic tumor cells. These results indicate that PSK activates PBL and TIL to exhibit ATK independently of IL-2/IL-2R systems.

Adult↗
PubMed1991

Fibrocellular tissue response after percutaneous transluminal coronary angioplasty. An immunocytochemical analysis of the cellular composition.

BACKGROUND: Restenosis after initial, successful percutaneous transluminal coronary angioplasty (PTCA) is due to fibrocellular proliferation. METHODS AND RESULTS: The present study focused on the nature of fibrocellular tissue in humans by use of immunocytochemical techniques. Four hearts (five coronary arteries) were investigated; time lapse between PTCA and death varied between 20 days (two arteries) and 1 year 7 months. Proliferating cells stained positive with smooth muscle cell-specific monoclonal antibodies. Cells from early proliferative lesions (20 days) have a phenotypic expression different from cells in "old" lesions. Proliferating cells stained positive with vimentin but were negative with desmin, irrespective of the lesion's age. CONCLUSIONS: The findings indicate a change in actin isoform expression of smooth muscle cells while adapting to a pathological state.

Actins↗
PubMed1991

Immunocytochemical localization of fodrin and ankyrin in bovine chromaffin cells in vitro.

We raised antibodies to brain fodrin and erythrocyte ankyrin and examined the distribution of the antigens in cultured bovine chromaffin cells by immunocytochemical techniques. Immunofluorescence microscopy of whole cells showed intense labeling for both proteins, but fine localization could not be determined. In contrast, in cell specimens mechanically unroofed before fixation, the distribution of the two proteins revealed an apparent difference in the ventral plasma membrane: immunofluorescence for fodrin was dense and mostly even, whereas that for ankyrin appeared as scattered dots. Immunogold electron microscopy of the unroofed cells showed that labeling for fodrin was localized in a network of thin filaments, the diameter of which was 2-3 nm at the thinnest portion. Ankyrin labeling was mostly associated with filaments 5-10 nm in diameter. Notably, labeling for both fodrin and ankyrin was found over the coated membrane. The present results indicate that fodrin and ankyrin in the chromaffin cell do not constitute a submembranous network as spectrin and ankyrin do in the erythrocyte; whereas fodrin is closely associated with the plasma membrane, ankyrin is mostly linked to the cytoskeleton. The existence of both proteins in the coated region implies that they are functionally related to exocytosis and/or to ensuing membrane retrieval in the chromaffin cell.

Animals↗
PubMed1991

Role of c-kit in mouse spermatogenesis: identification of spermatogonia as a specific site of c-kit expression and function.

Recent studies have shown that the dominant white spotting (W) locus encodes the proto-oncogene c-kit, a member of the tyrosine kinase receptor family. One symptom of mice bearing mutation within this gene is sterility due to developmental failure of the primordial germ cells during early embryogenesis. To elucidate the role of the c-kit in gametogenesis, we used an anti-c-kit monoclonal antibody, ACK2, as an antagonistic blocker for c-kit function to interfere with the development of male and female germ cells during postnatal life. ACK2 enabled us to detect the expression of c-kit in the gonadal tissue and also to determine the functional status of c-kit, which is expressed on the surface of a particular cell lineage. Consistent with our immunohistochemical findings, the intravenous injection of ACK2 into adult mice caused a depletion in the differentiating type A spermatogonia from the testis during 24-36 h, while the undifferentiated type A spermatogonia were basically unaffected. Intraperitoneal injections of ACK2 into prepuberal mice could completely block the mitosis of mature (differentiating) type A spermatogonia, but not the mitosis of the gonocytes and primitive type A spermatogonia, or the meiosis of spermatocytes. Our results indicate that the survival and/or proliferation of the differentiating type A spermatogonia requires c-kit, but the primitive (undifferentiated) type A spermatogonia or spermatogenic stem cells are independent from c-kit. Moreover, the antibody administration had no significant effect on oocyte maturation despite its intense expression of c-kit.

Animals↗
PubMed1991

Heart rate responses to autonomic drugs in sick sinus syndrome--correlation with syncope and electrophysiologic data.

To assess the influence of autonomic regulation on automaticity in patients with intrinsic sinus node dysfunction, heart rate responses to autonomic drugs were evaluated in 28 patients with sick sinus syndrome and in 8 normal subjects. Heart rates before and after intravenous administration of isoproterenol (Isp), propranolol, atropine, and methoxamine were measured. To compare the results with electrophysiologic data, heart rate and automaticity recovery time (ART) before and after pharmacologic autonomic blockade (AB) were evaluated. Seventeen patients without syncope showed a similar heart rate response after administration of Isp to that of normal subjects, but 11 patients with syncope showed a significantly lower response than patients without syncope. Responses to atropine and methoxamine were lower and response to propranolol was larger in patients as compared to normal subjects. However, no significant difference was observed between patients with and without syncope. Twelve patients showed severely prolonged max ART exceeding 5000 msec after AB. Seven of them showed preserved response to Isp and max ART before AB was significantly shorter than that after AB. The other 5 patients with lower response to Isp showed no significant change in max ART before and after AB. In conclusion, sympathetic regulation in patients with preserved response to Isp might compensate for the impaired intrinsic automaticity in preventing syncope even in patients with severely impaired intrinsic sinus node function.

Adult↗
PubMed1991

Accelerated glomerulosclerosis in alloxan-induced diabetic rabbits with anti-glomerular basement membrane nephritis.

To find how diabetes affects the processes of proliferative glomerulitis, we induced anti-glomerular basement membrane (GBM) nephritis by injection of anti-GBM antiserum in rabbits with alloxan diabetes (the DM-GN group) and in rabbits without the diabetes (the GN group), and compared the glomerular lesions between the two groups. Rabbits with alloxan diabetes only (the DM group) were also studied as control. Morphological examination showed that in the acute phase, the DM-GN and GN groups underwent histolysis of the glomerular loops, which gave rise to proliferative glomerulitis. In the later stages of glomerulitis, proliferating cells were crowded toward the axial portion of glomerular loops with an increase of intercellular matrix, and glomerular capillaries in the periphery of the glomerular loops recanalized. The amount of intercellular matrix of the axial portion increased more in the DM-GN group than in the GN group. Some of the glomerular lesions in the DM-GN group showed a formation of large nodules. The results suggested that diabetes could accelerate the formation of the intercellular matrix of glomerular loops in proliferative glomerulitis in rabbits, resulting in accelerated glomerulosclerosis.

Animals↗
PubMed1991

Behavior of chick primordial germ cells injected into the blood stream of quail embryos.

The distribution and behavior of chick primordial germ cells (PGC) injected into quail embryos were examined. PGC from chick embryos at stages 13-14 were injected into the blood stream of quail embryos at stages 15-20. After one day, the quail embryos were examined histologically. The chick PGC in the quail embryos could be readily identified by the histochemical PAS technique, whereas quail PGC were never stained by PAS. When the chick PGC were injected into the quail embryos during stages 15-18, they appeared mostly in the gonadal region of the recipient quail embryos. A few PGC were found at extragonadal sites. When the chick PGC were injected into the quail embryos at stages 19-20, in which the PGC of the recipient quail embryos had finished their migration into the gonads, most of the donor chick PGC were found at ectopic sites, in the head, trunk and limbs. These results indicate that most of the chick PGC, injected at the earlier stages 15-18, migrated to the gonadal anlagen of the recipient, while following later injection (from stage 19), most of the chick PGC migrated to ectopic sites.

Animals↗
PubMed1991

Retrospective analysis of late intensification therapy with high-dose methotrexate for standard-risk acute lymphoblastic leukemia in childhood (CCLSG-S811 study). The Children's Cancer and Leukemia Study Group.

Using the CCLSG-S811 protocol for children with standard-risk acute lymphoblastic leukemia (ALL), late intensification therapy (LIT) with high-dose methotrexate (HD-MTX) was conducted without randomization. Of 118 eligible patients, 114 attained complete remission and 82 maintained continuous complete remission (CCR) for at least 3 years, completing the entire S811 regimen. Among the latter, 74 patients received LIT with HD-MTX between 2-3 years after CCR onset. MTX (2,000 mg/m2 per dose per week) was administered by 24 h infusion and three doses were given every 12 weeks. Leucovorin rescue (15 mg/m2 i.v.) every 6 h was initiated 12 h after the end of MTX infusion for seven doses. As regular maintenance chemotherapy, intermittent (Regimen A) or continuous (Regimen B) MTX plus 6-mercaptopurine (6MP) combined with pulses of prednisolone and vincristine was administered (Koizumi S, Fujimoto T, Takeda T, et al. Cancer 1988; 61: 1292-1300). Retrospective analysis revealed that patients on Regimen A who started LIT earlier (within 2 years of CCR onset (n = 23)) showed a higher rate of event-free survival (EFS) at 8 years (95.5% +/- 4.4%, mean +/- S.E.) than patients who started LIT later (2.5 years after CCR onset (n = 18, 66.2% +/- 11.3%, p less than 0.01)). In addition, the superiority of four or five courses of the LIT (n = 39) as compared to 2 or 3 courses (n = 35) was noted for both regimens. The data suggest that early and aggressive LIT with HD-MTX may improve the long-term survival of childhood ALL patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

[Progression from latent cardiomyopathy to dilated cardiomyopathy: a review of five cases].

We report 5 patients, who had no cardiac abnormalities at their initial evaluation but progressed to dilated cardiomyopathy (DCM) during a mean follow-up period of 8.2 years. Their echocardiograms revealed increases in left ventricular (LV) end-diastolic dimensions, deterioration of LV contractions, and reduction in the LV wall thickness. Electrocardiographic changes were developed of rhythm disturbances, intensified ST-segment and T-wave changes, and the prolonged QRS durations. These findings, especially those of electrocardiography, seemed to be important for an early detection and characterization of DCM.

Adolescent↗
PubMed1991

Scanning and transmission electron microscopic observations of chick primordial germ cells with special reference to the extravasation in their migration course.

Chick primordial germ cells (PGCs) in the final course of their migration were observed by scanning (SEM) and transmission (TEM) electron microscopy, with an emphasis on their extravasation. The profile of the PGCs leaving blood vessels were first revealed under SEM. Chick embryos at stages 16 and 17 (about 2.5 days of incubation) were employed for the present study, since the PGCs emerging out of the vessels in teh gonadal area could be observed in high frequency at this developmental period. PGCs in the vessels showed a round profile, possessing many microvilli, while extravasating PGCs were rather oligovillous except the one side of the cell, where long filopodia extended toward the wall of the vessels. These filopodia seem to adhere to the wall of the vessels prior to emerging out. After extravasation, PGCs moved toward adjacent prospective gonadal epithelium and invaded it by amoeboidism. Following the settling down in the epithelium, PGCs showed rugged surface with few microvilli.

Animals↗