Biomedical subjects

S Okamoto

Publications and source records attributed to S Okamoto.

At least 217 records · Page 12Linked to original sources

PubMed1998

Expression of ADP-ribosyltransferase on normal T lymphocytes and effects of nicotinamide adenine dinucleotide on their function.

ADP-ribosyltransferase (ADPRT) is a glycosylphosphatidylinositol-anchored cell surface enzyme on CTL. Expression of this enzyme correlates with suppression of CTL functions in the presence of its substrate beta-nicotinamide adenine dinucleotide (NAD). To investigate the immunoregulatory importance of ADPRT on normal lymphocytes in vivo, NAD was injected into mice and the effects on cell-mediated and humoral immunity were assessed. Induction of both delayed-type hypersensitivity and CTL, but not Ab responses, are shown to be suppressed by NAD. Consistent with this, mature T cells, but not B cells or macrophages, express ADPRT and are able to ADP-ribosylate cell surface proteins. ADP-ribosylated molecules were identified as LFA-1, CD8, CD27, CD43, CD44, and CD45. Concomitant to ADP-ribosylation of these molecules, T cell trafficking to secondary lymphoid organs is suppressed by NAD. To examine whether this is due to effects of NAD on cell activation, Ag-stimulated responses were assayed in vitro. NAD is shown to inhibit induction of cell proliferation, cytotoxicity, and cytokine secretion. It is suggested that ADPRT regulates T cells on the level of transmembrane signaling via ADP-ribosylation of cell surface molecules. This effect is reported to be indirect, as it involves transmission of signals through TCRs, which are not ADP-ribosylated.

Animals↗

PubMed1998

Interleukin 7 transgenic mice develop chronic colitis with decreased interleukin 7 protein accumulation in the colonic mucosa.

We have demonstrated that intestinal epithelial cells produce interleukin 7 (IL-7), and IL-7 serves as a potent regulatory factor for proliferation of intestinal mucosal lymphocytes expressing functional IL-7 receptor. To clarify the mechanism by which locally produced IL-7 regulates the mucosal lymphocytes, we investigated IL-7 transgenic mice. Here we report that transgenic mice expressing murine IL-7 cDNA driver by the SRalpha promoter developed chronic colitis in concert with the expression of SRalpha/IL-7 transgene in the colonic mucosa. IL-7 transgenic but not littermate mice developed chronic colitis at 4-12 wk of age, with histopathological similarity to ulcerative colitis in humans. Southern blot hybridization and competitive PCR demonstrated that the expression of IL-7 messenger RNA was increased in the colonic mucosal lymphocytes but not in the colonic epithelial cells. IL-7 protein accumulation was decreased in the goblet cell-depleted colonic epithelium in the transgenic mice. Immunohistochemical and cytokine production analysis showed that lymphoid infiltrates in the lamina propria were dominated by T helper cell type 1 CD4+ T cells. Flow cytometric analysis demonstrated that CD4+ intraepithelial T cells were increased, but T cell receptor gamma/delta T cells and CD8alpha/alpha cells were not increased in the area of chronic inflammation. Increased IL-7 receptor expression in mucosal lymphocytes was demonstrated in the transgenic mice. These findings suggest that chronic inflammation in the colonic mucosa may be mediated by dysregulation of colonic epithelial cell-derived IL-7, and this murine model of chronic colitis may contribute to the understanding of the pathogenesis of human inflammatory bowel disease.

Animals↗

PubMed1998

Recombinant human granulocyte colony-stimulating factor (G-CSF) combined conditioning regimen for allogeneic bone marrow transplantation (BMT) in standard-risk myeloid leukemia.

We previously suggested that using a combined conditioning regimen including rhG-CSF with allogeneic BMT in refractory AML and CML in blast crisis might reduce the rate of relapse and improve disease-free survival, without any major side effects. In this study, we used the same protocol for 10 AML patients in complete remission (CR) and 6 CML patients in the chronic phase (CP). We compared disease-free survival as well as toxic side effects of the regimen with 6 AML patients in CR and 6 CML patients in CP treated with chemoradiotherapy without G-CSF. The conditioning regimen consisted of TBI and high-dose AraC. RhG-CSF was infused continuously at a dose of 5 microg/kg/day, starting 24 hr before the initial dose of total body irradiation (TBI) until the end of AraC therapy. In all 28 cases, there were no early stage deaths due to regimen-related toxicity (RRT). None of the 10 AML cases treated with the G-CSF combined regime relapsed. In 6 AML cases treated conventionally without G-CSF, one patient died of infection and another relapsed. There were no relapses in either CML group. In the combined G-CSF group, one patient died of interstitial pneumonitis 48 days after BMT, while the rest of the CML cases are still alive. There were no relapses with rhG-CSF and no serious adverse effects in terms of RRT, acute graft vs. host disease (GVHD), or leukocyte recovery.

Adult↗

PubMed1998

DNA ploidy, proliferative activities, and immunophenotype of malignant lymphoma: application of flow cytometry.

BACKGROUND: To explore the flow cytometric diagnosis of malignant lymphoma, we examined the deoxyribonucleic acid (DNA) ploidy, proliferative activities, and immunophenotype of surgical biopsy- and fine-needle aspiration (FNA)-derived materials. Our goal was to determine the possibility of making a diagnosis of malignant lymphoma by flow cytometric analysis of FNA-derived materials. METHODS: The DNA ploidy and proliferative indices including the percentage of S-phase fraction (SPF), G2 + M fraction (G2M), and Ki-67-positive fraction (Ki-67) were analyzed on the fresh materials from 84 consecutive patients with suspected malignant lymphoma. Flow cytometric analysis of surface antigens was simultaneously performed. Fourteen of the patients underwent FNA and subsequent surgical biopsy of the same lymph nodes for flow cytometric analysis. RESULTS: The proliferative indices of intermediate-grade non-Hodgkin's lymphomas (NHL) (n = 28) and high-grade NHL (n = 23) were significantly higher than those of the reactive hyperplasia (n = 25). The total for SPF + G2M of 6% was a satisfactory threshold for differentiating these NHL from reactive hyperplasia (sensitivity of 84%, specificity of 88%, and accuracy of 86%). However, low-grade NHL (n = 3) and Hodgkin's lymphoma (HL, n = 5) could not be discriminated by employing this parameter. DNA aneuploidy was seen in 13 of the 28 intermediate-grade NHL and 8 of the 23 high-grade NHL, whereas it was not seen in 25 reactive hyperplasia, 3 low-grade NHL, and 5 HL. The percentage of CD19-positive cells in B-cell NHL or CD3-positive cells in T-cell NHL was significantly higher compared with those for reactive hyperplasia. The percentage of CD16 + CD56-positive cells in natural killer (NK) cell NHL was extremely high, with a mean of 91.8%. Flow cytometric results for FNA-derived materials showed excellent correlation with those for surgical biopsy-derived specimens. CONCLUSIONS: Analyses of DNA ploidy, proliferative activities, and immunophenotype by flow cytometry (FCM) are useful for diagnosing intermediate- and high-grade NHL. Fine-needle aspiration is a less invasive approach than surgical biopsy, and, when combined with FCM, it may have a place in the diagnosis of NHL.

Biopsy, Needle↗

PubMed1998

CD45RChighCD4+ intestinal mucosal lymphocytes infiltrating in the inflamed colonic mucosa of a novel rat colitis model induced by TNB immunization.

To clarify the role of CD4(+) intestinal mucosal lymphocytes in chronic intestinal inflammation, we developed a new rat colitis model by immunization with 2,4,6-trinitrobenzenesulfonic acid (TNB) in an emulsion with an adjuvant followed by transrectal administration of a low dose of TNB. Moreover, we assessed the therapeutic effect of anti-CD4 monoclonal antibody (mAb) on this model. In concert with the development ofserum anti-TNB Abs, transmural and segmental colitis that mimics some characteristics of human Crohn's disease was induced in the immunized rats. Immunohistochemical analysis showed the increase of infiltrating lamina propria CD4(+) T cells. Flow-cytometric analysis of isolated cells from inflamed mucosa revealed that CD45RChighCD4(+) T cells were significantly increased. Interestingly, intraperitoneal administration of anti-CD4 mAbs could suppress severe inflammation in the model with decrease of anti-TNB Ab titer. After the treatment with anti-CD4 mAbs, CD45RChighCD4(+) T cells in the lamina propria and interferon-gamma mRNA expression in the colonic lamina propria CD4(+) T cells were decreased. These results indicated that Th1 CD4(+) intestinal mucosal T cells have a role in the progress of inflamed lesions in chronic enteritis. They implicate that a therapy targeting mucosal T cells expressing CD4 may be feasible in the treatment of human Crohn's disease.

Animals↗

PubMed1998

Proteoglycan distribution during healing of corneal stromal wounds in chick.

Proteoglycan distribution during corneal stromal healing in growing corneas of young chicks were histologically and immunohistochemically analysed. Single linear incisions to produce partial-thickness wounds were made in the corneas of 5 day old chicks. The corneas were harvested at different times after wounding and processed for either histochemical analyses using periodic acid-Schiff's reaction (PAS) or for indirect immunofluorescence analyses of lumican, keratocan, keratan sulfate, perlecan and laminin. Linear corneal stromal incisions were completely covered by migrated stratified epithelium by day 2 post wounding and resulted in a gaping wound with a thinner stroma. New stromal scar tissue formed between the epithelium and the original stroma that resulted in partial restoration of stromal thickness. During the first two to three weeks of healing, the stromal tissue filling the depression formed from the gaping wound, was hypercellular and PAS positive, indicating significantly higher levels of glycoprotein content but no new Bowman's membrane was formed. By four weeks, the scar tissue occupied a 2-3 mm wide region. Immunofluorescence analyses indicated that other major differences in the healing and normally growing stroma were the increased synthesis and deposition of perlecan and laminin. No differences were evident in the immunofluorescence for keratocan or keratan sulfate in the scar tissue, but the scar tissue did contain markedly decreased levels of lumican. Thus, the regulation of proteoglycan and glycoprotein synthesis is altered in the keratocytes that are recruited to the wounded regions in the growing corneal stroma of post-hatched young chicks. While synthesis and deposition of adhesive molecules including laminin and perlecan are elevated, the synthesis of one of the keratan sulfate proteoglycans, lumican, is reduced in the scar tissue as compared to the normally growing stroma.

Animals↗

PubMed1998

Resuscitation with hypertonic saline dextran reduces endothelial cell swelling and improves hepatic microvascular perfusion and function after hemorrhagic shock.

BACKGROUND: Hemorrhagic shock severely compromises hepatic microcirculation and function with tendency to promote hepatic insufficiency and multiple organ failure. MATERIAL AND METHODS: The aim of the study was to evaluate the effects of small volume resuscitation on liver microcirculation (intravital fluorescence microscopy and electron microscopy) and function (arterial ketone body ratio (AKBR) and bile flow), in a rat model of traumatic-hemorrhagic shock. One hour after hemorrhage (MAP 40 mm Hg) the rats were resuscitated with HSD (7.2% NaCl/10% dextran 60, 10% of shed blood/2 min, n = 8); DEX (6% dextran 60, 100% of shed blood/5 min, n = 8); or RL (Ringer lactate, 400% of shed blood/20 min, n = 6). RESULTS: HSD yielded a better recovery of sinusoidal perfusion (17.8 +/- 0.8% nonperfused sinusoids) than DEX (21.8 +/- 0. 7%, P < 0.05) and RL (23.9 +/- 0.9%, P < 0.01). Hemorrhagic shock produced a moderate increase of mean sinusoidal endothelial cell thickness, which was further enhanced by DEX and RL (P < 0.05 vs baseline), whereas HSD reduced the mean endothelial cell thickness toward baseline (P < 0.05 vs DEX and RL). Both AKBR and bile flow were profoundly reduced after 1 h shock. Resuscitation with DEX and RL produced a weak recovery, still remaining at shock level, while HSD infusion allowed a significant improvement of AKBR and bile flow (P < 0.05 vs shock). CONCLUSION: Reduction of mean endothelial cell thickness after HSD is very likely the mechanism for the amelioration of sinusoidal perfusion, resulting in a significant improvement of hepatic energetic status and excretory function.

Animals↗

PubMed1998

Central IL-1 differentially regulates peripheral IL-6 and TNF synthesis.

Centrally given interleukin (IL)-1 is known to induce a rapid rises in blood IL-6. To extend this and to examine the mechanism by which this occurs, the effects of intracerebroventricular (i.c.v.) injection of human recombinant IL-1 beta on mRNA expression of IL-6 and tumour necrosis factor (TNF) in the spleen and liver were examined in rats. I.c.v. injection of IL-1 produced a rapid rise of the tissue mRNA levels of Il-6 and TNF in both organs, prior to and/or in parallel with an increase in their serum levels. Pretreatment with chlorisondamine, a ganglionic blocking agent, inhibited the Il-6 responses, while it had little influence on the TNF responses. The results suggest that brain IL-1 induces peripheral production of IL-6, but not of TNF, through autonomic nervous system activation.

Animals↗

PubMed1998

Impact of brain death on hormonal homeostasis and hepatic microcirculation of transplant organ donors.

To elucidate the pathophysiological mechanisms involved in the deterioration of hepatic graft viability in brain-dead organ donors, the impact of brain death on hepatic microcirculation was investigated with respect to hormonal homeostasis and graft viability. Rats were assigned to two groups: group I (n = 6) served as sham controls, and in group II (n = 6), brain death was induced through insufflation of an intracranial balloon. Mean arterial pressure was elevated significantly within 5 min after the induction of brain death and then decreased significantly to below the control value. Urine osmolality was significantly lower and serum osmolality significantly higher than the control values. Antidiuretic hormone level was significantly lower than the control value. Bile secretion also decreased significantly. Furthermore, in group II there were significantly higher numbers of nonperfused sinusoids (15.9% vs 6.2% in group I), and sinusoidal stagnant and postsinusoidal venular adherent leukocytes (53.9/lobule and 258.6/mm2 versus 25.2/lobule and 124.8/mm2 in group I, respectively). In summary, sinusoidal perfusion is compromised after brain death, possibly, in part, through an increased leukocyte activation and accumulation in the hepatic microvasculature, leading to the deterioration of hepatic function.

Animals↗

PubMed1998

In vitro protein phosphorylation associated with cellular differentiation of Streptomyces griseus.

In vitro phosphorylation reactions with crude cellular extracts revealed that phosphorylation of a 17-kDa protein is associated with the onset of aerial mycelium formation in solid culture (but not submerged spore formation in liquid culture) of Streptomyces griseus. The possible importance of the 17-kDa protein phosphorylation in cellular differentiation was further indicated by inducing aerial mycelium formation in the presence of decoyinine and in studies using certain developmental mutants (relC, afsA, and M-1). It is proposed that the 17-kDa protein may play a role in cellular differentiation of S. griseus via its phosphorylation.

Bacterial Proteins↗

PubMed1998

Flow cytometric analysis of DNA content and Ki-67-positive fractions in the diagnosis of salivary gland tumors.

To explore the utility of flow cytometry (FCM) for the diagnosis of histopathology of salivary gland tumors, fresh materials taken at surgery from 23 Warthin's tumors, 57 pleomorphic adenomas, and 14 malignant tumors were analyzed for DNA ploidy and proliferative cell activities, including S-phase fraction (SPF), G2- plus M-phase fraction (G2M), and Ki-67-positive fraction. To facilitate this study, glands were taken from all major salivary sites and minor glands in the head and neck. DNA aneuploidy was not detected in the benign tumors. Nine of 14 malignant tumors showed DNA aneuploidy. The percentage of SPF or G2M of the malignant tumors was significantly higher than those of the benign tumors. The percentage of Ki-67-positive fraction of pleomorphic adenomas was comparable to that of malignant tumors and was significantly higher than that of Warthin's tumors. Ki-67 of 20% as a cut-off had a sensitivity of 88%, specificity of 100%, and accuracy of 91% for differentiating pleomorphic adenomas from Warthin's tumors. In analyzing DNA content and proliferative activities by FCM, we could distinguish among the three major histopathologies of salivary gland tumors. Warthin's tumors showed low SPF + G2M with low Ki-67, pleomorphic adenomas had low SPF + G2M with high Ki-67, and malignant tumor showed high SPF + G2M with high Ki-67. The high percentage of the Ki-67-positive fraction seen in pleomorphic adenomas may reflect their potential biological aggressiveness manifested as tumor recurrence or malignant transformation.

Adenolymphoma↗

PubMed1998

Variation in the ratio of respirable particulates over inhalable particulates by type of dust workplace.

OBJECTIVE: The aim of the present study was to clarify the quantitative relationship between respirable particulates and inhalable particulates in various dust workplaces. METHODS: Both respirable particulate and inhalable particulate concentrations were measured in 1644 dust workplaces by means of elutriation, and the ratio of respirable particulate mass over that of inhalable particulate (R/I ratio) was calculated for each workplace. RESULTS: Statistical analyses showed that the R/I ratio varied substantially, depending on the type of dust work. The ratio was highest in welding workplaces (mean +/- SD: 53 +/- 19%) and lowest in foundries (23 +/- 16%); the former value suggests that respirable particulate exposure may be underestimated in substantial parts of welding work when only the occupational exposure limit for inhalable particulates is taken for compliance testing. CONCLUSIONS: Simple compliance with the limit for inhalable particulates is not sufficient, and the limit for respirable particulates should also be simultaneously cleared.

Dust↗

PubMed1998

Monitoring of occupational exposure to dichloromethane by diffuse vapor sampling and urinalysis.

OBJECTIVE: The aim of the present study was to develop valid methods for monitoring of occupational exposure to dichloromethane (DCM). METHODS: Carbon cloth as an adsorbent in diffusive sampling was tested for its capacity to adsorb DCM vapor and to retain adsorbed DCM after termination of the exposure. Urine samples collected from DCM-exposed workers were analyzed for DCM by the head-space technique. After extraction with carbon disulfide, DCM in the cloth was analyzed on a DB-WAX capillary column by flame-ionization detection gas chromatography (FID-GC) and DCM in urine was analyzed by electron-capture detection (ECD)-GC. RESULTS: The diffusive sampling with carbon cloth as an adsorbent is applicable to 4-h monitoring of exposure to up to 100 ppm DCM vapor. DCM concentrations detected in end-of-shift urine samples correlated linearly with time-weighted average DCM concentrations measured in the breathing-zone air of the exposed workers; essentially the same exposure-excretion relationship was obtained by vapor monitoring for the afternoon 4-h period as compared with a whole day (8-h) of vapor monitoring. There was no sex difference in the exposure-excretion relation. CONCLUSIONS: Both personal diffusive sampling (at up to 100 ppm DCM and for up to 4 h) and biological exposure monitoring by urinalysis for DCM are applicable in occupational health as reliable measures of exposure to this chlorinated hydrocarbon solvent.

Air Pollutants, Occupational↗

PubMed1998

Dermatofibrosarcoma protuberans with fibrosarcomatous areas. Molecular abnormalities of the p53 pathway in fibrosarcomatous transformation of dermatofibrosarcoma protuberans.

Fibrosarcomatous (FS) change in a rare, but well-known phenomenon encountered in dermatofibrosarcoma protuberans (DFSP), and an increased chance in an adverse outcome has been suggested in patients with DFSP having FS areas (DFSP-FS). As altered p53 pathway has been suggested as having a potential role in tumour progression, we analysed the p53 gene and p53 protein together with the p53-related protein mdm2 and p21Waf1 in 5 cases of DFSP-FS and 13 of DFSP to ascertain whether the p53 pathway correlates to the fibrosarcomatous transformation of DFSP. Three of the five DFSP-FSs overexpressed p53 protein immunohistochemically, and one of them had a "missense" mutation of the p53 gene without immunohistochemical overexpression of mdm2 or p21Waf1. The other two DFSP-FSs with p53 overexpression demonstrated increased labelling indices of both mdm2 and p21Waf1. The three DFSP-FS patients with overexpression of p53 protein had frequent local recurrences, ranging from 3 to 5 in number with increasingly short intervals (mean 4.5 years), while one of the other two had no recurrences and the other, only one. None of the 13 DFSPs showed any alterations in the p53 gene or overexpressions of p53, mdm2 and p21Waf1, except for one DFSP having a "silent" mutation of the p53 gene. Three DFSPs had local recurrences once or twice with longer intervals to recurrence (mean 10.3 years). Although the number of cases examined is limited, the results suggest that alterations in the p53 pathway, such as overexpression of p53 protein by a mutated gene and mdm2 overexpression, are involved in fibrosarcomatous transformation in a subset of fibrohistiocytic tumours and possibly correlated with its more locally aggressive behaviour than that without p53 alterations or ordinary DFSP.

Adolescent↗

PubMed1998

Significance of increased plasma adrenomedullin concentration in patients with cirrhosis.

BACKGROUND/AIMS: Adrenomedullin recently discovered in human pheochromocytoma is a potent vasodilatory peptide mainly derived from vascular endothelial and smooth muscle cells. Hyperdynamic circulation, ultimately leading to ascites formation, has been attributed to peripheral vasodilatation in liver cirrhosis. However, little is known about the role of adrenomedullin in this condition. METHODS: Plasma adrenomedullin concentrations were measured by radioimmunoassay after extraction and purification in 28 cirrhotic patients without ascites, 12 cirrhotic patients with ascites and 10 healthy subjects. RESULTS: Plasma adrenomedullin concentrations in cirrhotic patients with ascites (12.7+/-4.5 fmol/ml) were significantly higher than those in cirrhotic patients without ascites (8.2+/-2.3 fmol/ml, p<0.005) and healthy subjects (5.8+/-0.8 fmol/ml, p<0.005). Interestingly, plasma adrenomedullin concentrations were highest in patients with refractory ascites (n=5, 15.8+/-3.0 fmol/ml) and were positively correlated with the Child-Pugh score (r=0.44, p<0.01). Moreover, plasma adrenomedullin concentrations were positively correlated with plasma renin activity (r=0.63, p<0.0001), plasma aldosterone (r=0.60, p<0.0001) and plasma norepinephrine concentrations (r=0.60, p<0.0001), and negatively correlated with creatinine clearance (r=-0.61, p<0.0005) and urinary sodium excretion (r=-0.44, p<0.02). Stepwise multiple regression analysis using certain independent variables, including Pugh's score, vasoactive substances, renal function and hemodynamic parameters, showed that the adjusted R square was highest when plasma renin activity and creatinine clearance (standard coefficient=0.53, -0.49, respectively) were considered (adjusted R square=0.61, p<0.0001). CONCLUSIONS: Plasma adrenomedullin concentrations increased with the progression of liver cirrhosis and were highest in cirrhotic patients with refractory ascites. In addition, elevated adrenomedullin was associated with activation of the renin-angiotensin-aldosterone and sympathetic nervous systems, and with functional renal impairment in cirrhosis. Considering the potent vasodilatory action of adrenomedullin, increased adrenomedullin may participate in the hyperdynamic circulation, ultimately leading to ascites formation, in patients with liver cirrhosis.

Adrenomedullin↗

PubMed1998

Taurin-conjugated ursodeoxycholic acid has a reversible inhibitory effect on human keratinocyte growth.

Tauroursodeoxycholic acid (TUDC) is one of the most hydrophilic taurin conjugated bile acids. TUDC has a suppressive effect on DNA synthesis in primary cultured rat hepatocytes. In this study, we investigated the growth inhibitory effect of TUDC on cultured human keratinocytes. TUDC suppressed the proliferation of keratinocytes in a dose dependent fashion, as measured by both cell counts and 5-bromo-2'-deoxyuridine (BrdU) uptake. Keratinocytes reproliferated and reached almost the same cell number as control after removal of TUDC from the medium. TUDC (1 mM) had no effect on the cell viability, as measured by the dye exclusion test. Epidermal sheets stratified in the presence of TUDC appeared thinner than those stratified without TUDC. These results suggest that TUDC has a reversible growth suppressive effect on human keratinocytes through the mechanism other than cytotoxicity and would be applicable for the treatment of hyperproliferative skin disorders such as psoriasis.

Animals↗

PubMed1998

Trichomonas foetus meningoencephalitis after allogeneic peripheral blood stem cell transplantation.

A 34-year-old man with refractory acute myelogenous leukemia underwent allogeneic peripheral blood stem cell transplantation (PBSCT) from his HLA-matched sibling. Engraftment was prompt and no acute GVHD developed. However, high fever persisted even after engraftment, and the patient developed headache, diplopia, vertigo and nuchal rigidity on day 20 posttransplant. Cerebrospinal fluid (CSF) showed pleocytosis with no detectable microorganisms. Despite therapy with broad-spectrum antibiotics, antifungal agents and antituberculous drugs, he developed rapid mental deterioration with seizures and died on day 40. Just prior to his death, trichomonads were isolated from both CSF and urine. Scanning electron microscopic examination identified the trichomonad as Trichomonas foetus. At autopsy, trichomonads were detected histopathologically in an area involving meningoencephalitis. To our knowledge, this is the first case of T. foetus meningoencephalitis in a recipient of allogeneic PBSCT and, more importantly, the first human case of T. foetus infection.

Adult↗

PubMed1998

An essential GTP-binding protein functions as a regulator for differentiation in Streptomyces coelicolor.

The Streptomyces coelicolor obg gene, which encodes a putative GTP-binding protein of the Obg/Gtp1 family, was characterized. The obg gene was essential for viability. Introduction of multiple copies of obg into wild-type S. coelicolor suppressed aerial mycelium formation. A single amino acid substitution at any of six positions was introduced into the GTP binding site of Obg, and the mutated proteins were expressed in wild-type cells. Obg(P168-->V) exerted a more accentuated suppressive effect on aerial mycelium formation than did the wild-type Obg protein. In contrast, Obg(G171-->A) accelerated the development of aerial mycelium. These results show that Obg protein functions as a pivotal regulator for the onset of cell differentiation through its ability to bind GTP. Western analysis revealed that expression of obg is regulated in a growth phase-dependent manner, indicating a sharp decrease just after onset of aerial mycelium development or at the end of vegetative growth. Obg was a membrane-bound protein as determined by immunoelectron microscopy.

Bacterial Proteins↗