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Biomedical subjects

T Kohama

Publications and source records attributed to T Kohama.

At least 37 records · Page 2Linked to original sources
PubMed1998

The effect of leustroducsin B on the production of cytokines by human mesenchymal cells.

Leustroducsin B (LSN-B), a novel colony-stimulating factor (CSF) inducer, has been shown to have various biologic activities in vivo. To compare the CSF-inducing activity of LSN-B in vitro with that of the well-known cytokine inducer, interleukin-1beta (IL-1beta), bacterial lipopolysaccharide (LPS), and phorbol 12-myristate 13-acetate (PMA), we measured granulocyte (G)-CSF and granulocyte-macrophage (GM)-CSF levels that were induced with the stimuli in several mesenchymal cells. The results indicated that each stimulant displayed a different profile in the induction of G-CSF and GM-CSF. Next, to investigate if LSN-B induces cytokines other than G-CSF and GM-CSF, we characterized cytokines that were induced with LSN-B from bone marrow stromal cells (BMSCs). The results showed that a variety of cytokines, including G-CSF and GM-CSF, were induced in both clonal and primary BMSCs. From these results, we speculate that LSN-B induces cytokine production via a regulatory pathway distinct from that of IL-1beta, LPS, or PMA and that this signaling of LSN-B might lead to the production of a variety of cytokines in BMSCs. In addition, from our in vitro and in vivo results, we speculate that the biologic activities of LSN-B in vivo might be based on its own cytokine-inducing activity even though the target cell type of LSN-B in vivo remains to be determined.

Anti-Bacterial Agents↗
PubMed1998

Roles of sphingosine-1-phosphate in cell growth, differentiation, and death.

Recent evidence suggests that branching pathways of sphingolipid metabolism may mediate either apoptotic or mitogenic responses depending on the cell type and the nature of the stimulus. While ceramide has been shown to be an important regulatory component of apoptosis induced by tumor necrosis factor alpha and the Fas ligand, sphingosine-1-phosphate (SPP), a further metabolite of ceramide, has been implicated as a second messenger in cellular proliferation and survival induced by platelet-derived growth factor, neuronal growth factor, and serum. SPP protects cells from apoptosis resulting from elevations of ceramide. Inflammatory cytokines stimulate sphingomyelinase, but not ceramidase, leading to accumulation of ceramide, whereas growth signals also stimulate ceramidase and sphingosine kinase leading to increased SPP levels. We propose that the dynamic balance between levels of sphingolipid metabolites, ceramide, and SPP and consequent regulation of different members of the mitogen-activated protein kinases (JNK versus ERK) family is an important factor that determines whether a cell survives or dies.

Animals↗
PubMed1997

Expression of telomerase activity in human chorion.

Telomerase activation is required for cellular immortalization and is found in most malignant tumors. Normal somatic cells are generally telomerase-negative, except for stem cells in renewing tissues. During pregnancy, human trophoblast continues to proliferate and acts as proliferating stem cells for the development of chorion and the formation of placenta. In the present study, a total of 105 chorions from placentas at various weeks of gestation were examined for telomerase activity using the telomeric repeat amplification protocol (TRAP) assay. Twenty-five of 33 (76%) normal early chorions at 5 to 9 weeks gestation were telomerase-positive. Chorions from early spontaneous abortions also exhibited telomerase activity but at a low level. In contrast, only 2 (4%) late chorions at 34 to 41 weeks gestation expressed telomerase activity. Significant telomerase activity was observed in trophoblast cell fractions of chorion, demonstrating trophoblast to be the source of the activity. Expression of human telomerase catalytic subunit (hTRT) was observed in early chorions, but not in late placenta, and there was a close correlation between telomerase activity and hTRT expression. In contrast, expression of human telomerase RNA component (hTR) was observed in both early and late chorions and was not liked to telomerase activity. These findings suggest that telomerase activity in chorion is critically regulated over the course of gestation, associated with hTRT expression. The findings of the present study also appear to support the emerging concept that normal somatic cells with stem cell-like characteristics can express telomerase activity.

Choriocarcinoma↗
PubMed1997

Telomerase activity in human endometrium.

Human uterine endometrium undergoes a complex pattern of changes in proliferation and secretory activity during the menstrual cycle. In the present study, telomerase activity in normal endometrium was examined using a non-radioisotope PCR-based telomeric repeat amplification protocol assay. Various levels of telomerase activity were detected in the 60 normal endometrial samples examined, depending on the phase of the menstrual cycle. Of 21 proliferative-phase endometrial samples, 20 (95%) expressed telomerase activity, whereas 8 of 19 (42%) secretory-phase or menstrual endometrial samples did (P = 0.002). Five of nine (56%) samples from atrophic endometrium from postmenopausal women also expressed telomerase activity. Eleven of 21 (52%) endometrial samples in the proliferative phase expressed high telomerase activity detectable after 100-fold dilution of extracts, whereas none of the 19 endometrial samples from the secretory phase or during menstruation and none of the 9 postmenopausal endometrial samples did (P < 0.001). The highest activity was observed in the late proliferative phase, but activity dramatically decreased with the progression of the secretory phase. Surprisingly, the levels of telomerase activity detected in the late proliferative phase were comparable to those detected in the endometrial cancers examined. Immunohistochemical analysis of the expression of proliferating cell nuclear antigen revealed that telomerase activity is closely correlated with endometrial cell proliferative activity. These findings indicate that normal endometrium expresses telomerase, the activity of which changes dramatically over the course of the menstrual cycle, suggesting in turn that telomerase is a regulated enzyme linked to cellular proliferation and that hormone functions may be involved in its regulation.

Biomarkers↗
PubMed1997

A technique of minilaparotomy-assisted vaginal hysterectomy.

In minilaparotomy-assisted vaginal hysterectomy, the operation begins vaginally by opening the peritoneal folds and ligating the uterine vessels and uterosacral ligaments. Minilaparotomy is then performed for myomectomy, cutting the fallopian tubes and the utero-ovarian ligaments and detaching any adhesions on the anterior peritoneal angle. In 26 women who underwent this procedure, the feasibility rate was 100% and no intraoperative complications or postoperative morbidity was observed (except in one case of ovarian bleeding), indicating that vaginal hysterectomy assisted by minilaparotomy is a feasible approach for hysterectomy in the setting of large myomas, myomas with adhesions caused by endometriosis or previous pelvic surgery, and adenomyosis.

Adult↗
PubMed1997

Effects of dehydroepiandrosterone and other sex steroid hormones on mammary carcinogenesis by direct injection of 7,12-dimethylbenz(a) anthracene (DMBA) in hyperprolactinemic female rats.

The present study was performed to investigate the effects of dehydroepiandrosterone (DHEA) compared with those of sex steroid hormones on the mammary tumor induced by local injection of 7,12-dimethylbenz(a) anthracene (DMBA) in hyperprolactinemic female rats. Under sustained hyperprolactinemia induced by pimozide (PMZ) from day 21, DMBA was injected locally into the mammary glandular tissues on day 73. Rats were divided into 5 groups as follows; steroid free (DP group), 17 beta-estradiol (DP + E2 group), testosterone (DP + T group), progesterone (DP + Prog group), or dehydroepiandrosterone (DP + DHA group). The growth pattern and histological classification of the tumor in these 5 groups and rats treated only with DMBA (D group) were examined. All of the tumors grew to a size of 10 mm in diameter and after retaining the size for a certain duration, increased the size rapidly again (onset of rapid tumor growth). The period from the day of DMBA administration to that of onset of the rapid tumor growth in DP group was shorter than in D group, and the period in DP + DHA was longer than DP group and longest in steroid-treated groups. The incidence of adenocarcinoma was 2 tumors/16 animals in D group, 9/11 in DP group, 5/11 in DP + Prog group, 2/7 in DP + E2 group, 2/8 in DP + T group, and 0/10 in DP + DHA group. The incidence of adenocarcinoma in each steroid group except in DP + Prog group was lower than in DP group. These results suggest that prolactin (PRL) increases the incidence of adenocarcinoma in the DMBA-induced mammary tumor model, and DHEA especially decreases the incidence of adenocarcinoma.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

Parameters for plaque formation in the potency assay of Japanese measles vaccines.

Parameters for plaque formation by measles vaccine strains licensed in Japan were studied. For the plaque test, inoculum volume was one of the critical factors for obtaining an appropriate titre of the sample. A linear relationship between the inoculum volume and the apparent reciprocal titre was discovered, enabling the comparison of absolute titres. Another factor affecting the infectivity was the strain-specific temperature sensitivity in the plaque assay. Although all the vaccine strains tested showed the highest titre at 35 degrees C, the pattern of the temperature sensitivity differed from one strain to another. These factors must be taken into consideration in order to obtain an appropriate titre of a vaccine virus.

Animals↗
PubMed1996

Detection and comparison of viral antigens in measles and rubella rashes.

Measles and rubella skin lesions were immunocytochemically compared by the avidin-biotin-peroxidase complex method for detecting viral antigens. Cryostat sections of biopsied specimens of the skin were stained with mouse monoclonal antibodies to P protein of measles virus and to E1 protein of rubella virus. The measles virus antigen was concentrated in the corneal layer and the keratinocytes of the epidermis and in the surface part of the dermis in the biopsy secimens taken within 6 days after the onset of rash. On the other hand, the rubella virus antigen was dispersed in all parts of the dermis and the subcutaneous layer but not in the epidermis in the biopsy specimens taken within 2 days after the onset of rash. The differences in the distribution and density of the viral antigen and in the times of its detection suggest distinct patterns of spread of infection with each virus in the skin.

Adolescent↗
PubMed1996

Leustroduscin B, a new cytokine inducer derived from an actinomycetes, induces thrombocytosis in mice.

Leustroduscin B (LSN-B), a novel colony-stimulating factor (CSF) inducer produced by an actinomycetes, has previously been shown to induce CSF production in bone marrow stromal cells. To determine the biological activity of LSN-B on hematopoiesis in vivo, LSN-B was administered intraperitoneally to mice every day for three to six days. Peripheral platelet counts were markedly elevated on days 4 through 6 compared with the control mice injected with vehicle. Serum II/6 levels were low (0.8 ng/ml) or virtually undetectable in the drug treated groups. This cytokine profile suggests that LSN-B induction of thrombocytosis is mechanistically distinct from other cytokine inducers such as IL-1 or FK-565.

Animals↗
PubMed1995

Isolation of the measles virus hemagglutinin protein in a soluble form by protease digestion.

The hemagglutinin (H) glycoprotein was isolated in a soluble form by digesting measles virus particles with an endoproteinase, Asp-N (from a Pseudomonas fragi mutant). Digestion of H with Asp-N brought about glycopeptides in three different forms, depending on the cleaving site: AHD, which has an M(r) of 66,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and which formed a disulfide-linked homodimer with an M(r) of 132,000, and two monomeric digestion products, AHM-1 (with an M(r) of 64,000) and AHM-2 (with an M(r) of 58,000). The susceptibility of the H glycoprotein to the protease depended on the enzyme concentration. AHD was readily formed at a low concentration of Asp-N, while AHM-1 and AHM-2 required higher and even higher protease concentrations, respectively. All of the cleavage products reacted with monoclonal antibodies to various epitopes of the H protein; however, only AHD showed a significant hemagglutinin activity on African green monkey erythrocytes. The hemagglutinin activities of AHM-1 and AHM-2 were restored after a monoclonal antibody lacking the hemagglutination-inhibiting activity was added to the reaction mixture. AHDs purified by size-exclusion high-pressure liquid chromatography had two associating forms; one had an M(r) higher than and the other an M(r) as high as that of a tetramer. The former was associated noncovalently in addition to having two intermolecular disulfide bonds, and the latter was associated covalently with a single intermolecular disulfide bond and was also duplicated through a noncovalent association. In addition, both AHM-1 and AHM-2, having no intermolecular disulfide bond, were in a dimer form. These results suggest that AHM-1 and AHM-2 are monovalent in the hemagglutinin activity, while AHDs are divalent. Comparative analyses of the N termini of these soluble glycopeptides with the sequence of H suggested that the cysteine residue at position 139 was responsible for the intermolecular disulfide bonding between the monomeric H glycoproteins. The cysteine at position 154 was also suggested to participate in the forming of the intermolecular disulfide bond.

Amino Acid Sequence↗
PubMed1994

Augmentation of host resistance against bacterial infection by treatment with leustroducsin B, a new CSF inducer.

We tested the in vivo activity of leustroducsin B (LSN B), a new colony-stimulating factor (CSF) inducer isolated from the culture broth of Streptomyces platensis, with mice infected with Escherichia coli. Treatment with LSN B augmented the host resistance to lethal infection of E. coli at doses between 0.1 mg/kg and 1 mg/kg. Serum interleukin-6 (IL-6) levels were found to increase after this treatment, and superoxide anion generation of neutrophils was enhanced in vivo, suggesting that LSN B augmented the host resistance at least in part by inducing IL-6, which subsequently enhanced the bactericidal activity of the neutrophils.

Animals↗
PubMed1994

Diabetic scleredema and scleroderma-like changes in a patient with maturity onset type diabetes of young people.

A 21-year-old housewife with maturity onset type diabetes of young people developed scleredema diabeticorum, scleroderma-like skin thickness on forearms and dorsum of hands, digital sclerosis and cheiroarthropathy. She had diabetes mellitus since the age of 11 years. Her grandfather on the mother's side, her mother and 3 of 5 her mother's brothers and sisters have diabetes mellitus. Blood glucose was 295 mg/dl. Urinary glucose was 5.3 g/day. Nail fold capillary microscopy revealed a progressive systemic sclerosis pattern. Histologically, hematoxylin and eosin sections from back and forearm skin demonstrated broad collagen bundles separated by widened clear spaces throughout the thickened dermis.

Adult↗
PubMed1993

Screening method for colony-stimulating factor inducers using a human bone marrow stromal cell line, KM-102.

A new screening method for inducers of colony-stimulating factors (CSFs) was established using KM-102, a human bone marrow stromal cell line as the producer. In this method, the assay system which uses CSF dependent cell lines is combined with the CSF production system. Interleukin-1 (IL-1), which is known to upregulate CSF production in many cell populations, was used as a positive control for production of granulocyte CSF (G-CSF) and granulocyte-macrophage CSF (GM-CSF). Induction in the positive controls was clearly detected within 24 hours. Activators of protein kinase C (PKC), protein phosphatase inhibitors and lipopolysaccharide (LPS) were positive in this assay system, but muramyl dipeptide (MDP) and Bestatin which are known macrophage activators, were negative. Inducers of CSFs were successfully detected using this assay method. Among 1,600 microbial strains tested, 2 actinomycete strains were found to produce active substances. One strain produces teleocidin-A, a strong activator of PKC, and the other strain produces a mixture of active compounds including three novel compounds. These three compounds do not induce terminal differentiation of HL-60 cells, suggesting that they are not teleocidin-like substances and form a new class of CSF inducers.

Bone Marrow↗
PubMed1993

Novel microbial metabolites of the phoslactomycins family induce production of colony-stimulating factors by bone marrow stromal cells. I. Taxonomy, fermentation and biological properties.

Three metabolites were isolated from the culture broth of an actinomycete strain identified as Streptomyces platensis SANK 60191, that induce the production of colony-stimulating factors (CSFs) by stromal cell line KM-102 at ED50 concentrations from 40 to 200 ng/ml. The compounds induced quantities of granulocyte CSF (G-CSF) and granulocyte-macrophage CSF (GM-CSF) comparable to those induced by interleukin-1, a strong CSF inducer. These metabolites were called leustroducsins (A, B and C) and were later found to be structurally related to phoslactomycins. This is the first report of CSF inducing activity by members of the phoslactomycin class.

Antifungal Agents↗