Search PubMed⌕ Search

Biomedical subjects

K Maruyama

Publications and source records attributed to K Maruyama.

At least 127 records · Page 7Linked to original sources

A case of erythropoietic protoporphyria with liver cirrhosis suggesting a therapeutic value of supplementation with alpha-tocopherol.

Erythropoietic protoporphyria (EPP) was diagnosed in a 27-year-old man based on a typical clinical history, and a marked increase in erythrocyte and fecal protoporphyrin concentrations. Although liver disease is not a common feature in EPP, he had slight liver dysfunction. A percutaneous liver biopsy was performed and it showed minimal hepatocellular damage and many reddish brown pigment deposits in hepatocytes, Kupffer cells, portal histiocytes, bile canaliculi and small biliary radicles. Electron microscopic findings confirmed that these deposits were composed of protoporphyrin crystals. Liver biochemistry remained well for >2 years, but deteriorated rapidly and second liver biopsy obtained 28 months after the first biopsy revealed the development of liver cirrhosis. We treated the patient with intravenous administration of dl-a-tocopherol acetate (vitamin E; 500 IU/body/day). Following the administration of vitamin E, the concentration of protoporphyrin in erythrocytes decreased significantly and the liver function tests were improved. Sixteen weeks later he showed the full clinical and biochemical recovery suggesting that vitamin E supplementation might be useful in treating patients with EPP who developed liver damage.

Journal Article↗

Modulated vasodilator responses to natriuretic peptides in rats exposed to chronic hypoxia.

Natriuretic peptides (NPs), such as atrial natriuretic peptide (ANP), C-type natriuretic peptide (CNP), and adrenomedullin (ADM), are endogenous vasodilators acting via specific receptors. This study addressed the question of how pulmonary artery (PA) responses to these peptides and the gene expression of their receptors are modulated in pulmonary hypertension rat models exposed to chronic hypoxia. In this study, isometric tension was measured in PA rings exposed to these NPs and 8-bromoguanosine 3', 5'-cyclic monophosphate (8-bromo-cGMP). It was compared with messenger ribonucleic acid (mRNA) levels of NP-A and -B receptors, which bind to ANP and CNP, respectively, as determined by ribonuclease (RNase) protection assay. Chronic hypoxia increased the maximal relaxation elicited by ANP, but the responses to CNP and 8-bromo-cGMP were unchanged. Chronic hypoxia did not change NP-A and -B receptor mRNA levels. The results showed that pulmonary artery response to atrial natriuretic peptide is selectively enhanced, possibly via a post-transcriptional modulation of its receptor in chronically hypoxia rats. These pharmacological characteristics of atrial natriuretic peptide are consistent with the hypothesis that the atrial natriuretic peptide system is protective against the progression of pulmonary hypertension.

Adrenomedullin↗

Enhancement of antitumor immunity against B16 melanoma tumor using genetically modified dendritic cells to produce cytokines.

Dendritic cells (DC) that have been genetically modified to express cytokine genes may be novel tools for inducing antitumor immune responses. In the present study, the pMX retroviral vector was modified to express the mouse IL-2 (mIL-2pMX) and mouse IL-12 (mIL-12pMX) genes. Supernatants from 293 cells transfected with pMX retroviral vectors were harvested and used to transduce mouse lin- bone marrow (BM) progenitor cells. After 48 h co-culture with pseudotype retrovirus, BM cells were cultured for 12 days in the presence of mGM-CSF, mSCF and mTNF-alpha to obtain a DC-enriched fraction. Flow cytometric analysis showed that GFP protein expression in these cultures was 20-40% and that 40-50% of the cultured BM cells were positive for the DC marker, DEC205. About 60% of cells sorted for DEC205 also expressed GFP. The supernatants of DC-mIL-2 and DC-mIL-12 cultured for 48 h contained 5.2 +/- 0.15 and 33.9 +/- 2.6 ng cytokine protein per milliliter, respectively. Intratumoral injection of DC-mIL-2 or DC-mIL-12 on days 8 and 15 after the intradermal injection of 1 x 105 B16F10 cells, resulted in a significant reduction in tumor size by day 21, as compared with mice treated with unmodified DC or DC-GFP. Longer term analysis as assessed at day 42 revealed that B16 tumor-bearing mice treated with cytokine gene-modified DC survived significantly longer than mice from other groups. Spleen cells obtained from DC-treated mice were specifically sensitized for the generation of CTL by subsequent restimulation with gene-modified DC. These results suggested that DC genetically modified to express IL-2 or IL-12 can induce potent antitumor responses against well-established, poorly immunogenic B16F10 tumors. Gene Therapy (2000) 7, 2113-2121.

Animals↗

Intracellular site of gamma-secretase cleavage for Abeta42 generation in neuro 2a cells harbouring a presenilin 1 mutation.

Previously, we reported that mutations in presenilin 1 (PS1) increased the intracellular levels of amyloid beta-protein (Abeta)42. However, it is still not known at which cellular site or how PS1 mutations exert their effect of enhancing Abeta42-gamma-secretase cleavage. In this study, to clarify the molecular mechanisms underlying this enhancement of Abeta42-gamma-secretase cleavage, we focused on determining the intracellular site of the cleavage. To address this issue, we used APP-C100 encoding the C-terminal beta-amyloid precursor protein (APP) fragment truncated at the N terminus of Abeta (C100); C100 requires only gamma-secretase cleavage to yield Abeta. Mutated PS1 (M146L)-induced Neuro 2a cells showed enhanced Abeta1-42 generation from transiently expressed C100 as well as from full-length APP, whereas the generation of Abeta1-40 was not increased. The intracellular generation of Abeta1-42 from transiently expressed C100 in both mutated PS1-induced and wild-type Neuro 2a cells was inhibited by brefeldin A. Moreover, the generation of Abeta1-42 and Abeta1-40 from a C100 mutant containing a di-lysine endoplasmic reticulum retention signal was greatly decreased, indicating that the major intracellular site of gamma-secretase cleavage is not the endoplasmic reticulum. The intracellular generation of Abeta1-42/40 from C100 was not influenced by monensin treatment, and the level of Abeta1-42/40 generated from C100 carrying a sorting signal for the trans-Golgi network was higher than that generated from wild-type C100. These results using PS1-mutation-harbouring and wild-type Neuro 2a cells suggest that Abeta42/40-gamma-secretase cleavages occur in the Golgi compartment and the trans-Golgi network, and that the PS1 mutation does not alter the intracelluar site of Abeta42-gamma-secretase cleavage in the normal APP proteolytic processing pathway.

Amyloid Precursor Protein Secretases↗

Molecular mechanism of the reversibility of hepatic fibrosis: with special reference to the role of matrix metalloproteinases.

The participation of matrix metalloproteinases (MMP) and their specific inhibitors, the tissue inhibitors of matrix metalloproteinases (TIMP), in both the formation and degradative recovery processes of liver fibrosis were mainly reviewed from the molecular biological aspect. Since authors first reported increased activity of interstitial collagenase in the early stage of hepatic fibrosis in rats induced by chronic CCl4 intoxication, in baboons fed alcohol chronically and in patients with alcoholic fibrosis, other investigators have also demonstrated increased activity biologically and histochemically. However, species-specific differences in response have been found and gene-level research on the rat model has not demonstrated increased mRNA transcription of collagenase. It has also been clarified that activated stellate cells can also produce matrix components. Very recently, authors observed the participation of interstitial collagenase in the recovery from experimental hepatic fibrosis by using polymerase chain reaction northern blotting and in situ hybridization. The in situ hybridization findings not only demonstrated the cells responsible for interstitial collagenase, but also suggested a great deal about the mechanism of recovery from fibrosis. Hepatic stellate cells are activated via the expression of c-myb and nuclear factor-kappaB (NFkappaB) which is induced by oxidative stress, and inhibited by antioxidant (1-alpha-tocopherol) and butylated hydroxytoluene. The activation mechanism is now being revealed. The relationship between the activation mechanism of stellate cells and the production and secretion of MMP and TIMP in the formation and recovery process of hepatic fibrosis should be investigated from the promoter gene level. This approach might help develop a new strategy for the treatment of liver fibrosis.

Animals↗

Case-control study of perinatal factors and hepatoblastoma in children with an extremely low birthweight.

BACKGROUND: There is a significant association between hepatoblastoma and low birthweight. A case-control study was conducted to reveal risk factors for hepatoblastoma in children of extremely low birthweight (< 1,000 g). METHODS: Prenatal and postnatal histories, including parental histories, of 12 hepatoblastoma cases and 75 birthweight-matched controls were compared. RESULTS: The gestational age of the hepatoblastoma cases (23-32 weeks: median 25 weeks), tended to be lower than that of the controls (23-36 weeks; median, 27 weeks; P = 0.072). The time for an infant's bodyweight to return to the same level as the birthweight also tended to be longer in hepatoblastoma cases than in controls (P = 0.055). All hepatoblastoma cases received oxygen therapy for a period of 4-508 days (median 114 days), which was significantly longer than the 0-366 days (median 62 days) in the controls (P = 0.022). Furosemide was given to all hepatoblastoma cases and was used for a significantly longer period in these infants (6460 days; median 89 days) than in the controls (0-241 days; median 44 days P = 0.027). A univariate Cox regression demonstrated that the time taken to regain bodyweight at birth and the duration of both oxygen therapy and furosemide treatment were significantly associated with the development of hepatoblastoma (hazard ratio (HR)= 1.044, P= 0.013; HR = 1.006, P= 0.001; and HR = 1.007, P= 0.001, respectively). Although there were significant correlations between the factors, a multivariate Cox regression analysis identified the duration of oxygen therapy as a significant independent risk factor (HR = 1.006, P = 0.001). CONCLUSIONS: Oxygen therapy and furosemide treatment, along with the rate of growth, are risk factors for the development of hepatoblastoma in children of extremely low birthweight, and the duration of oxygen therapy is the most important factor in predicting the development of hepatoblastoma. Further studies are necessary to determine the real reasons for the development of hepatoblastoma and to protect children of low birthweight from the development of cancer.

Case-Control Studies↗

Electrochemical characterization and DNA-binding property of dipyridophenazine complexes of osmium (II).

Novel dipyridophenazine (DPPZ) complexes of osmium (II), [Os(L)2(DPPZ)]2+ [L = 2,2'-bipyridyl (bpy)(1), 4,4'-diamino-2,2'-bipyridyl (DA-bpy)(2), 4,4'-dimethyl-2,2'-bipyridyl(DM-bpy)(3), and 4,4'-dicarboxyl-2,2'-bipyridyl (DC-bpy)(4)] have been synthesized and characterized. The DNA-binding properties of the complexes were studied by electrochemical methods. As the results, complex 2 shows higher affinity to DNA than other osmium complexes. The binding constant, K of complex 2 to calf thymus DNA has been determined to be 2.3 x 10(7) M-1 by normal pulse voltammetry (NPV).

Animals↗

Experimental study of critical exponents of electrical conductivity in a two-dimensional continuum percolation system

In this paper an experimental study is presented for critical exponents of electrical conductivity in an inverse Swiss-cheese model. Filled circles are drawn on random positions of square paper in drawing ink with an X-Y plotter, and electrical resistance between both opposite sides is measured automatically by the use of general purpose interface bus system. Electrical conductivity is obtained from the inverse of the electrical resistance. Electrical conductivity in a bond process is also measured with the same system. It is confirmed that the critical exponent of electrical conductivity of a continuum two-dimensional inverse Swiss-cheese model is different from that of a discrete one.

Journal Article↗

Targeting chemotherapy to solid tumors with long-circulating thermosensitive liposomes and local hyperthermia.

The effectiveness of the combination of long-circulating, thermosensitive liposomes and hyperthermia is described. Small-sized, thermosensitive liposomes that encapsulate doxorubicin (DXR-PEG-TSL (SUV)) have a prolonged circulation time and are extravasated to targeted solid tumors in vivo, where they preferentially release the agent in an anatomical site subjected to local hyperthermia. Liposomes were prepared by the incorporation of amphipathic polyethyleneglycol (PEG) to prolong their circulation time. DXR-PEG-TSL (SUV) was retained longest and was accumulated most efficiently in solid tumors in Balb/c mice. The combination of DXR-PEG-TSL (SUV) and hyperthermia at the tumor sites 3 h after injection, gave high concentrations of doxorubicin in tumor tissue and resulted in more effective tumor retardation and increased survival time. A large amount of DXR-PEG-TSL (SUV) was extravasated into the tumors during circulation for 3 h after injection, suggesting that the encapsulated drug was released into the interstitial spaces of the lesions by local hyperthermia. This system is expected to be clinically valuable for the delivery of a wide range of chemotherapeutic agents in the treatment of solid tumors.

Animals↗

Ataxia caused by mutations in the alpha-tocopherol transfer protein gene.

A 48 year old woman with ataxia with vitamin E deficiency is described. Gene analysis identified two point mutations in exon 1 of the alpha-tocopherol transfer protein (alpha-TTP) gene, one missense mutation and an upstream initiation codon mutation in the 5'-untranslated region (Kozak sequence). The latter mutation is the first one identified in the translation regulatory region. This mutation decreased the level of alpha-TTP protein expression. The clinical features included uncommon urinary disturbance and deafness and relatively rare retinitis pigmentosa. Supplementary therapy increased her serum vitamin E concentration to the normal range with mild improvement of the deep senses.

Ataxia↗

Lung cancer screening: minimum tube current required for helical CT.

PURPOSE: To investigate the minimum tube current required for helical computed tomography (CT) for lung cancer screening. MATERIALS AND METHODS: Thirty helical scans of the lung were obtained at effective tube currents of 50, 30, 20, 18, 12, 10, and 6 mAs in seven healthy volunteers. Computer-generated nodules 6 mm in diameter that showed ground-glass opacity were superimposed on the images. The image quality and detectability of nodules were evaluated subjectively by six observers. The SDs of measured CT numbers were calculated. The results were analyzed according to location in the lung. RESULTS: Compared with the subjective quality of images obtained at 50 mAs, the subjective quality of images obtained at 20 mAs was not significantly different. The detectability of nodules was not significantly degraded by reducing the tube current to 20 mAs in the upper zone of the lung, to 12 mAs in the middle zone, or to 18 mAs in the lower zone. The SDs at the apex and base of the lung were larger than those at other levels, and the difference became greater as the dose was reduced. CONCLUSION: The minimum tube current required for screening helical CT differs for different locations in the lung. An ideal CT protocol for the lung should permit the tube current to be changed during helical scanning.

Adult↗

Cytoplasmic beta-catenin accumulation as a predictor of hematogenous metastasis in human colorectal cancer.

The membranous, cytoplasmic and nuclear levels of beta-catenin were evaluated immunohistochemically in archival tissue specimens from 96 Japanese patients with primary colorectal carcinoma who had undergone surgery. The relationships between beta-catenin and clinicopathological variables were analyzed statistically. Reduced beta-catenin immunoreactivity in the cell membranes of cancer cells was found in 70% of the tumors, and cytoplasmic and nuclear accumulation of beta-catenin were found in 68 and 66% of tumors, respectively. Significant correlations between cytoplasmic beta-catenin accumulation and the depth of invasion, venous invasion and focal dedifferentiation were observed. Cytoplasmic beta-catenin accumulation was also found to be a useful predictor of hematogenous metastasis (hazard ratio = 8.94, p = 0.054), though neither a reduced cell membrane level nor nuclear accumulation of beta-catenin correlated with metastasis.

Adenocarcinoma↗

Ranolazine attenuates palmitoyl-L-carnitine-induced mechanical and metabolic derangement in the isolated, perfused rat heart.

The effect of ranolazine, a novel anti-ischaemic drug that stimulates the activity of pyruvate dehydrogenase, on palmitoyl-L-carnitine-induced mechanical dysfunction and metabolic derangement in isolated perfused rat hearts has been studied and compared with the effect of dichloroacetate, an activator of pyruvate dehydrogenase. Rat hearts paced electrically were perfused aerobically at constant flow by the Langendorff technique. Palmitoyl-L-carnitine (4 microM) increased left ventricular end-diastolic pressure and reduced left ventricular developed pressure (i.e. induced mechanical dysfunction); it also reduced tissue levels of adenosine triphosphate and increased tissue levels of adenosine monophosphate (i.e. induced metabolic derangement). These functional and metabolic alterations induced by palmitoyl-L-carnitine were attenuated by ranolazine (5, 10, and 20 microM) in a concentration-dependent manner. In contrast, dichloroacetate (1 and 10 mM) did not attenuate palmitoyl-L-carnitine-induced mechanical and metabolic derangement. In the normal (palmitoyl-L-carnitine-untreated) heart, however, ranolazine did not modify mechanical function and energy metabolism. These results suggest that ranolazine attenuates palmitoyl-L-carnitine-induced mechanical and metabolic derangement in the rat heart, and that the beneficial action of ranolazine is not because of the energy-sparing effect or activation of pyruvate dehydrogenase.

Acetanilides↗

In vivo targeting by liposomes.

This review deals with the current status of newly developed pendant-type PEG-immunoliposomes (Type C), carrying monoclonal antibodies or their fragments (Fab') at the distal ends of the PEG chains. In terms of target binding of Type C, two different anatomical compartments are considered. They are mouse lung endothelium as a readily accessible site via the intravascular route and the implanted solid tumor as a much less accessible target site reached via extravasation. Distearoyl phosphatidylethanolamine derivatives of PEG with a carboxyl group (DSPE-PEG-COOH) and dipalmitoyl phosphatidylethanolamine derivatives of PEG with a maleimidyl group (DPPE-PEG-Mal) at the PEG terminus were newly synthesized. Small unilamellar liposomes (90-130 nm in diameter) were prepared from phosphatidylcholine and cholesterol (2 : 1, m/m) containing 6 mol% of DSPE-PEG-COOH or DPPE-PEG-Mal. For targeting to the vascular endothelial surface in the lung, 34A antibody, which is highly specific to mouse pulmonary endothelial cells, was conjugated to PEG-liposomes (34A-Type C). The degree of lung binding of 34A-Type C in BALB/c mouse was significantly higher than that of 34A-Type A, which is an ordinary type of immunoliposome (without PEG derivatives). For targeting to solid tumor tissue, 21B2 antibody (anti-human CEA) and its Fab' fragment were used. The targeting ability of Fab'-Type C was examined by using CEA-positive human gastric cancer strain MKN-45 cells inoculated into BALB/c nu/nu mice. Fab'-Type C showed low RES uptake and a long circulation time, and enhanced accumulation of the liposomes in the solid tumor was seen. The small Fab'-Type C predominantly passed through the leaky tumor endothelium by passive convective transport. These studies offer important insights into the potential of Type C liposomes for target-specific drug delivery.

Animals↗

The effect of oral clonidine premedication on lumbar cerebrospinal fluid pressure in humans.

Alpha-2 adrenergic agonists including clonidine decrease cerebral blood flow. The specific actions of clonidine on cerebrospinal fluid (CSF) pressure in humans remain to be elucidated. We evaluated the effect of oral clonidine premedication on lumbar CSF pressure in patients without intracranial disease. Seventy-four patients undergoing subarachnoidal block were divided randomly into either a clonidine or a control group. In the clonidine group, the patients were premedicated orally with 5 microg/kg clonidine 60 min before arrival in the operating room. Subarachnoidal puncture was performed via midline approach using a 23-gauge needle at the L2-3 or L3-4 intervertebral space with the patient in the lateral decubitus position. Before the injection of local anesthetic, lumbar CSF pressure was measured. Lumbar CSF pressure was 8.1+/-2.4 mmHg in the clonidine group, which was significantly lower than that in the control group (9.4+/-2.8 mmHg, p<0.05). The cerebral perfusion pressures were 76.2+/-12.5 mmHg in the clonidine group and 91.7+/- 15.4 mmHg in the control group (p<0.001). In the clonidine group, preanesthetic mean blood pressure had a significant correlation with lumbar CSF pressure (r=0.619, p=0.019). We conclude that Lumbar CSF pressure was attenuated by oral premedication with 5 microg/kg clonidine. Clonidine also contributed to a significant correlation between preanesthetic mean blood pressure and CSF pressure.

Administration, Oral↗

Effect of calcimimetic agent, KRN568, on gastrin secretion in healthy subjects.

KRN568 is a calcimimetic compound which acts on the calcium sensing receptors (CaR) on the parathyroid gland to suppress secretion of PTH. A recent report has demonstrated that CaRs are expressed on cultured human antral gastrin cells and that gastrin secretion is stimulated by an increase in extracellular calcium level. However, the effect of KRN568 on serum gastrin levels has yet to be clinically assessed. We therefore studied the effect of this calcimimetic on gastrin secretion in healthy subjects enrolled in the phase 1 study for KRN568 currently carried out in Japan. Single doses of KRN568, ranging from 25 mg to 400 mg, were orally administered to 6 healthy male volunteers at fasting and after meal. One subject proved to be a poor metabolizer (PM) for this compound and showed more than 10-fold high concentrations of plasma KRN568 (fasting Cmax 90.8 and non-fasting 83.8 ng/ml) compared to the other 5 individuals (Cmax 6.5 +/- 2.2 and 7.4+/- 1.6 ng/ml, respectively). Plasma gastrin levels showed mild but apparent increase (from 30 to 125 pg/ml) in this particular subject, while there were no significant increases in the other five people (from 34 +/- 6 to 63 +/- 3 pg/ml) after oral administration of 400 mg KRN568 at fasting. In the PM, administration of KRN568 resulted in extraordinarily high serum drug levels associated with transient increase of gastrin levels. This observation suggested that calcium-induced stimulation of gastrin secretion in human was mediated by a mechanism involving CaR. Potential side effects related to the increased gastrin secretion may be warranted in the practical use of this compound.

Administration, Oral↗