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Biomedical subjects

S Kitajima

Publications and source records attributed to S Kitajima.

At least 73 records · Page 4Linked to original sources
PubMed1998

Ultrastructural changes in motor endplates of the lumbrical muscles of rats induced by a microsomal Ca2+ ATPase inhibitor, 2,5-di(tert-butyl)-1,4-hydroquinone.

Female Wistar rats were treated orally for 5 days with 80 mg/kg body weight of 2,5-di(tert-butyl)-1,4-hydroquinone (DTBHQ), a microsomal Ca2+ ATPase inhibitor. Motor endplates of the lumbrical muscles were examined by light and electron microscopy. There was a decrease in body weight in the treated rats from the first day after administration, and toxic signs appeared after the third day, such as adoption of a prone position, salivation, lacrymation, and an abnormal gait and/or muscle weakness. No remarkable macroscopic or light microscopic changes were noted in the lumbrical muscles as well as other peripheral nerves of hind legs of the treated rats killed 1 day after the last DTBHQ treatment. Ultrastructurally, neurotoxicity characterized by loss of synaptic vesicles and mitochondria in the motor endplates, and by destruction of the motor terminals was detected in the lumbrical muscles of the treated rats. These results strongly indicate that DTBHQ targets the motor endplates in the rat lumbrical muscles and suggest that the resultant damage is responsible for the appearance of neurological signs, such as an abnormal gait and loss of muscle control.

Administration, Oral↗
PubMed1998

Aluminum taken up by transferrin-independent iron uptake affects the iron metabolism in rat cortical cells.

We previously demonstrated that cultured human fibroblasts internalize iron via transferrin-independent iron uptake (Tf-IU), redox, and receptor-mediated endocytosis uptake systems [Oshiro, S., Nakajima, H., Markello, T., Krasnewich, D., Bernardini, I., and Gahl, W.A. (1993) J. Biol. Chem. 268, 21586 21591]. Of these iron transport systems, the Tf-IU system is involved in the accumulation of transition metals in various mammalian cells. It is also known that in experimental animals fed aluminum (Al), Al at micromolar level selectively accumulates in the brain. In the present study, we examined the effects of Al accumulated in the brain cells on iron transport by the Tf-IU system and iron metabolism, using primary cultures from fetal rat cerebral cortex. Pretreatment of cells with 200 microM Al-nitrilotriacetate upregulated the Tf-IU system for iron. Moreover, of various metals tested, Al markedly upregulated the Tf-IU activity. To examine the influence of Al on iron metabolism, the interaction between Al accumulated in the cells and iron-responsive element binding protein (IRE-BP), a cellular iron regulator, was examined by Northern blot analysis, and activity assay: Al decreased the Tf receptor mRNA level and increased the aconitase activity of IRE-BP. The increase of aconitase activity by Al was also observed in vitro. These results suggest that Al accumulated in cortical cells affects iron metabolism.

Aconitate Hydratase↗
PubMed1998

Expression of proliferating cell nuclear antigen (PCNA) and apoptosis related antigen (LeY) in epithelial skin tumors.

We semiquantitatively analyzed expression of PCNA and LeY in seborrheic keratosis (SK), actinic keratosis (AK), Bowen's disease (BD), and squamous cell carcinoma (SCC), using immunocytochemically stained tissue sections. PCNA expression increased in a stepwise fashion from low levels in normal skin to higher expressions within SK, AK, BD, and SCC. The levels of LeY protein also increased in this order. The PCNA expression pattern shifted from expression limited to the basal and suprabasal cell layers (in normal skin and SK) to expression extending to the upper squamous and granular layers (in AK, BD, and SCC). On the other hand, the pattern of LeY expression shifted from the granular (in normal skin) to the upper squamous (in SK and AK) and suprabasal layers (in BD and SCC). These findings suggest that PCNA expression is related to the degree of cell proliferation and that LeY expression is related to the degree of differentiation or keratinization of tumor cells. In addition, PCNA and LeY show a reciprocal relationship in their expression.

Bowen's Disease↗
PubMed1998

Vascular levels and cGMP-increasing effects of nicorandil administered orally to rats.

We examined a relation between cyclic guanosine monophosphate (cGMP) production in thoracic aorta, as an indicator probably reflecting the vascular response, and the vascular as well as plasma levels of nicorandil administered orally to rats. Nicorandil (3 mg/kg) given orally was rapidly absorbed, reaching the maximal plasma (approximately 2,600 ng/ml) and vascular concentrations (approximately 176 ng/g) at 15 min after the dosing and thereafter decreased rapidly. Even 2 h after the dosing, the level of the vascular cGMP formation in vivo remained significantly higher (approximately 1,000 fmol/mg increase from the control level) in the nicorandil-treated group, compared with the vehicle-treated one, and was enough to develop pronounced muscle relaxation in in vitro aortic preparations. However, it seems that the vascular cGMP increase in vivo was not always correlated to the plasma concentration of nicorandil, because the plasma concentration (approximately 750 ng/ml corresponding to 3.5 microM) at 2 h after the dosing, caused only relatively low cGMP production (300-400 fmol/mg increase from the control level), when tested in in vitro aortic preparations. Our study may indicate, therefore, that the vascular cGMP elevation in vivo is due to the content of nicorandil effectively remaining at its vascular targets of action as well as the plasma nicorandil concentration.

Administration, Oral↗
PubMed1998

Ultrastructural localization of nicorandil in the heart of rats.

To examine the intracellular localization of nicorandil in the heart, [14C]nicorandil and [3H]nicorandil (3 mg kg(-1)) were given orally to rats. The maximum concentration (Cmax) of nicorandil in the myocardium was reached 15 min after the oral dosing. At this time subcellular localization of nicorandil was examined. Nicorandil and its denitrated metabolite, SG-86 were found in mitochondrial fractions and in cytosolic and microsomal fractions of the heart. Electron-microscopic autoradiograms recorded 15min after oral dosing of 3 mg kg(-1) [3H]nicorandil to rats also showed the presence of silver grains generated by the radioactive nicorandil or its metabolites in the mitochondria of the heart. We conclude that nicorandil given orally to rats is distributed in mitochondria of the heart.

Administration, Oral↗
PubMed1998

Interrelationship of cardiovascular effects, plasma levels of nicorandil, and vascular cGMP formation in conscious rats.

The relationship between the dual activity of nicorandil (KATP channel-opening activity and nitrate-like action), plasma levels, and changes in vascular cGMP levels and cardiovascular parameters was investigated in conscious rats. Nicorandil (3 mg kg(-1), p.o.) was rapidly absorbed and caused a significant reduction in blood pressure, lasting for at least 1 h, increases in heart rate and femoral blood flow, and decreases in femoral vascular resistance. These were entirely abolished by intravenous glibenclamide (20 mg kg(-1)). The plasma concentration of nicorandil reached a maximum 30 min after dosing. After administration of nicorandil, a correlation was observed between blood pressure and plasma nicorandil level or femoral vascular resistance. A significant increase (P < 0.05) in the cGMP content of the thoracic aorta occurred 15 min after administration of nicorandil, and persisted for at least 2 h. These results imply that nicorandil induces vasodilatation by opening KATP channels in peripheral resistance vessels, leading to overt reduction of blood pressure, but acts on conductance vessels mainly through nitrate-like activity.

Administration, Oral↗
PubMed1998

Macroscopic distribution of coronary atherosclerotic lesions in cholesterol-fed rabbits.

In the present study we macroscopically examined a change in the distribution of coronary atherosclerosis in cholesterol-fed rabbits. Rabbits were fed a cholesterol-enriched diet for 15 weeks, then replaced by a normal diet, and were sacrificed at 15, 24, 32 and 42 weeks after the start of the experiment. The coronary atherosclerosis in the cholesterol-fed rabbits was distributed more densely in the proximal portion than in the middle and distal portions, and the lesions were severe at 24 and 32 weeks after the start of the experiment. comparison of lesions in the three portions at these time points showed that the percentages of lesion areas in the proximal portion, the middle portion and the distal portion were approximately 51%, 21 to 25% and 0.2 to 3.7%, respectively. Macroscopic observation of the coronary atherosclerotic lesions showed that the lesions formed over the vessel lumen in the proximal portion within the range of approximately 5 mm from the orifice of the left coronary artery. In the middle portion, the lesions formed predominantly around the orifices of branches as small patchy lesions from 1 to 3 mm in diameter. These findings support previous histopathological reports that suggested that the incidence of stenosis in the proximal portion was high, and the incidence of lesion occurrence in the middle and the distal portions varied. The method, macroscopical investigation of the coronary artery, is useful for analyzing coronary atherosclerosis in the rabbit.

Animals↗
PubMed1998

[Chemotherapy of Hansen's disease in Japan--present status].

In order to know leprosy chemotherapy status in Japan, three recently conducted Government-supported nation-wide survey, namely chemotherapy research group survey (Takizawa, 1994, 71 cases) follow up result of Takizawa's study (Miyagi, 1997, 59 cases) and leprosy patient registry (Goto, 1996, 130 cases) were compared and analyzed. For most fresh and relapse cases, multi-drug therapy were applied, among them rifampicin/dapsone or rifampicin/dapsone/clofazimine combinations were selected in about half of new cases and about 1/3 of relapse cases. In many cases dose and intervals were based on WHO protocol, however smaller dosage was used in some cases. Quinolone (ofloxacin) was used in 40% of cases during the therapy. Reversal reaction was observed in 7/71 cases and erythema nodosum leprosum was observed in 6/71 cases. In order to prevent chemotherapy-induced deformities, we propose a modified protocol for new cases accompanied by reactional status, which starts with clofazimine monotherapy and followed by WHO/MB.

Anti-Infective Agents↗
PubMed1998

Characterization of a transferrin-independent iron uptake system in rat primary cultured cortical cells.

Multiple transferrin-independent iron uptake (Tf-IU) systems are known to be involved in the internalization of free iron salt in various mammalian cells. However, the characteristics of a Tf-IU system in cortical cells are not clear. In this study, we characterized the Tf-IU systems in both cortical and glial predominant (GP) cells from rat cerebral cortex to investigate the mechanism by which iron (Fe) or aluminum (Al) accumulates in the cerebral cortex. The Tf-IU systems in both cells were temperature- and Ca2*-dependent. The upregulation of Tf-IU system in GP cells by Fe- or Al-nitrilotriacetate (Fe- or AI-NTA) was 2- or 4-fold higher than that of cortical cells. Chemiluminescence analysis specific for O2- and 1O2 also showed that the production of active oxygen species in Fe-loading GP cells was twice higher than that of Fe-loading cortical cells. These results suggest the existence of Tf-IU systems in both cortical and GP cells similar to those of HeLa cells whose Tf-IU is metal- and Ca-2+ dependent, and that the glial cells contribute to metal accumulation in cerebral cortex. The present study may help to explain the pathogenesis of neurodegenerative disorders caused by inducing oxidative stress.

Aluminum↗
PubMed1997

p32 protein, a splicing factor 2-associated protein, is localized in mitochondrial matrix and is functionally important in maintaining oxidative phosphorylation.

Human p32, originally cloned as a splicing factor 2-associated protein, has been reported to interact with a variety of molecules including human immunodeficiency virus Tat and complement 1q (C1q). p32 protein is supposed to be in the nucleus and on the plasma membrane for the association with human immunodeficiency virus Tat and C1q, respectively. None of the interactions, however, is proven to have a physiological role. To investigate the physiological function of p32, we determined the intracellular localization of p32. The fractionation of cells, fluorescent immunocytochemistry, and electron microscopic immunostaining show that p32 is exclusively localized in the mitochondrial matrix. We cloned a Saccharomyces cerevisiae homologue of human p32 gene, referred to yeast p30 gene. The yeast p30 protein is also localized in the mitochondrial matrix. The disruption of the p30 gene caused the growth retardation of yeast cells in a glycerol medium but not in a glucose medium, i.e. the impairment of the mitochondrial ATP synthesis. The growth impairment was restored by the introduction of the human p32 cDNA, indicating that p30 is a functional yeast counterpart of human p32. Taken together, both p32 and p30 reside in mitochondrial matrix and play an important role in maintaining mitochondrial oxidative phosphorylation.

Amino Acid Sequence↗
PubMed1997

Phosphorylation of human general transcription factors TATA-binding protein and transcription factor IIB by DNA-dependent protein kinase--synergistic stimulation of RNA polymerase II basal transcription in vitro.

DNA-dependent protein kinase (DNA-PK) has been known to catalyze phosphorylation of a number of regulatory factors involved in DNA replication and transcription such as simian virus 40 T antigen, p53, c-Myc, Sp1, and RNA polymerase II (Pol II). We examined the possibility that DNA-PK phosphorylates the general transcription factors TATA-binding protein (TBP) and transcription factor (TF) IIB, which play key roles in the formation of transcription initiation complex with Pol II. By using a highly purified preparation of DNA-PK from Raji cells, both TBP and TFIIB were shown to be phosphorylated in vitro by DNA-PK. We then investigated the effect of the phosphorylation of these factors on Pol II basal transcription. Stepwise analysis of preinitiation complex formation by electrophoretic mobility shift assay revealed that the phosphorylation of TBP and TFIIB by DNA-PK did not affect the formation of promoter (P)-TBP and P-TBP-TFIIB complexes but synergistically stimulated the formation of P-TBP-TFIIB-TFIIF-Pol II complex. Similarly, combination of the phosphorylated TBP and TFIIB synergistically stimulated Pol II basal transcription from adenovirus major late promoter. These observations suggest that DNA-PK could positively regulate the Pol II basal transcription by phosphorylating TBP and TFIIB.

DNA-Activated Protein Kinase↗
PubMed1997

Characterization of the human thrombopoietin gene promoter. A possible role of an Ets transcription factor, E4TF1/GABP.

Thrombopoietin (TPO), the ligand for c-Mpl, is a cytokine that regulates megakaryocyte growth and development. We have cloned the 5'-flanking region of the human TPO gene and analyzed its promoter activity. The human TPO gene promoter lacks a TATA box and directs transcription initiation at multiple sites over a 50-nucleotide region. Transient expression in a human liver cell line (PLC) of promoter fragment-luciferase reporter gene constructs containing a series of 5'-truncated sequences or site-directed mutations identified a sequence 5'-ACTTCCG-3' from -69 to -63 as a positive cis-acting element for high level expression of TPO gene. This sequence contains a core motif (C/A)GGA(A/T) for Ets family proteins in the noncoding strand. Gel mobility shift assays performed with nuclear protein from PLC cells identified a DNA binding protein(s) specific for the element. Anti-E4TF1-60(GABPalpha) or anti-E4TF1-53/47(GABPbeta) antibodies supershifted the complex in gel shift assay. Furthermore, co-expression of E4TF1-60 and E4TF1-53/47 squelched TPO gene expression in PLC and HepG2 cells. It is concluded that Ets family transcription factor E4TF1(GABPalpha/beta), an ubiquitously expressed protein, is required for high level expression of the TPO gene in liver.

Base Sequence↗
PubMed1997

Autoantibody reactive with the human general transcription factor TFIIF in sera from patients with autoimmune disorders.

Transcription factor (TF) IIF, a heteromeric protein composed of two subunits, RAP30 and RAP74, is required for both specific initiation and elongation of mRNA synthesis by RNA polymerase II. We have identified high titre of specific autoantibodies against the RAP74 subunit of TFIIF in sera from patients with systemic lupus erythematosus (SLE) as well as those with rheumatoid arthritis (RA), periarteritis nodosa (PN), Sjögren's syndrome (SS), dermatomyositis (DM), and mixed connective tissue disease (MCTD) by Western blot or immunoprecipitation. The epitopes recognized by autoantibodies were shown to be preferentially clustered at the central charged region. Anti-RAP74 autoantibody was shown to suppress the activity of TFIIF-stimulated elongation of mRNA synthesis by RNA polymerase II. It is concluded that some patients with autoimmune disorders develop specific autoantibodies against the RAP74 subunit of TFIIF.

Adult↗
PubMed1997

Perianal Paget's disease years after rectal adenocarcinoma removal.

BACKGROUND: Perianal Paget's disease often coincides with anorectal carcinoma, which extends into the epidermis from a contiguous organ. OBJECTIVE: Our purpose was to present a patient with perianal Paget's disease who had a rectal adenocarcinoma excised 14 years previously in another hospital and to determine whether there is a relationship between the perianal Paget's disease and the rectal adenocarcinoma. METHODS: We examined the resected specimens of the rectal adenocarcinoma and the perianal Paget's disease histologically. RESULTS: In the resected specimen of the rectal adenocarcinoma, Paget cells were present within the anal epidermis adjacent to the rectal adenocarcinoma. The Paget cells showed the same histochemical and immunohistological findings as the adenocarcinoma cells. CONCLUSION: There was a close relationship between the perianal Paget's disease and the rectal adenocarcinoma. It is probable that the Paget cells were derived from direct spread from the rectal adenocarcinoma.

Adenocarcinoma↗
PubMed1997

Triple extramammary Paget's disease.

BACKGROUND: Triple extramammary Paget's disease (TEPD) has been considered to be rare in the English literature, and its incidence and characteristics are unclear. There are many therapeutic options for treating extramammary Paget's disease (EPD). OBJECTIVE: Our purpose was to investigate how many TEPD cases have been reported previously and to describe their characteristics. We also describe the effectiveness of radiotherapy for them. METHODS: We report two TEPD cases, and summarize previously reported TEPD cases together with our cases. RESULTS: Twenty-three TEPD cases have been reported previously. Of these, 19 cases have been in Japan. All but one patient with TEPD were male. Their axillary lesions often showed no eruptions or very slight erythema. Radiotherapy for our cases was effective although the effectiveness of radiotherapy is controversial. CONCLUSION: In genital Paget's disease bilateral axillae should be examined histologically, even if they show no or slight eruptions. Radiotherapy may be useful for EPD, particularly axillary Paget's disease.

Aged↗
PubMed1997

Telomerase elevation in pancreatic ductal carcinoma compared to nonmalignant pathological states.

Telomerase activity was measured in surgically resected tissues of 20 human pancreatic ductal carcinomas, 12 adenomas, 5 pancreatitis tissues, 14 normal pancreatic ducts, and 13 normal pancreatic tissues (primarily made up of acinar cells) using a PCR-based telomerase assay. Relative telomerase activity was expressed as the equivalent telomerase intensity of the number of cells of a human pancreatic cancer cell line, MIA PaCa-2, per microgram of protein in the tissue samples. The median value (25th percentile, 75th percentile) of relative telomerase activity in pancreatic carcinomas was 13.2 (3.58, 244), which was significantly higher relative to normal tissues, normal ducts, pancreatitis tissues, and adenomas (P < 0.0001). When the cutoff value of relative telomerase activity was set at 1.00 and 3.00, the positivity rates of telomerase activity in pancreatic ductal carcinomas were 100 and 80%, respectively. Some of the adenoma samples displayed a weak telomerase ladder. However, when semiquantitatively analyzed, the relative telomerase activity of all adenoma tissues was less than 1.00 equivalent cells per microgram protein of the tissues, which was equivalent to the values encountered in normal ducts. Thus, our results indicate that reactivation of telomerase may occur at a late stage of pancreatic ductal carcinogenesis. Therefore, telomerase may be a specific marker for distinguishing pancreatic cancer from pancreatitis and adenomas.

Adenocarcinoma↗
PubMed1996

Inhibition of the nerve growth factor-induced outgrowth of neurites by trichostatin A requires protein synthesis de novo in PC12D cells.

Trichostatin A (TSA) inhibits the activity of histone deacetylase and blocks both oncogenic ras-induced and nerve growth factor-induced (NGF-induced) outgrowth of neurites from PC12 cells. Cells of the PC12D subline extend neurites very rapidly in response to NGF, basic fibroblast growth factor (bFGF), dibutyryl cAMP (dbcAMP) and to staurosporine, even in the presence of an inhibitor of RNA synthesis, as do primed PC12 cells or cultured sympathetic neurons. TSA at 100 nM selectively blocked the NGF- and bFGF-induced outgrowth of neurites from PC12D cells, but not the outgrowth induced by dbcAMP or staurosporine. The NGF-induced changes in morphology with the relocalization of F-actin, were not inhibited by TSA. However, the subsequent formation of growth cones and the outgrowth of neurites was blocked. The activation of mitogen-activated protein (MAP) kinases in NGF-stimulated cells was also unaffected by TSA. When TSA was added to cells that were extending neurites in response to NGF, the number of neurite-bearing cells decreased after a lag period. In the presence of inhibitors of RNA or protein synthesis namely, actinomycin D, cordycepin, and cycloheximide, TSA no longer blocked the NGF- and bFGF-dependent outgrowth of neurites from PC12D cells. Regardless of the effect of TSA, the rapid outgrowth of neurites from PC12D cells was unaffected by the presence of cycloheximide, which inhibited protein synthesis by 97%, as determined by monitoring the incorporation of [35S]methionine/cysteine. This study provides proof that the NGF-induced elongation of neurites does not require protein synthesis de novo. These observations suggest that TSA might not inhibit the early signal-transduction pathway of NGF, but might block the late pathway, which is related to the formation of growth cones and/or neurites. Cellular conditions that no longer allow the NGF- and bFGF-mediated elongation of neurites might be produced by TSA via synthesis of some specific protein(s) due to changes in RNA(s) synthesis de novo.

Animals↗