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Biomedical subjects

M Koyama

Publications and source records attributed to M Koyama.

At least 127 records · Page 7Linked to original sources
PubMed1996

Maintenance of imprinting of the insulin-like growth factor II gene (IGF2) and the small nuclear ribonucleoprotein polypeptide N gene (SNRPN) in the human uterus and leiomyoma.

The insulin-like growth factor II gene (IGF2) is thought to be involved in the growth of uterine smooth muscle tumors. We studied the allele-specific expression of IGF2 in 20 patients with uterine leiomyomas by analyzing restriction fragment length polymorphisms (RFLP), because IGF2 is a maternally imprinted gene and only the paternal allele is exclusively expressed in human somatic tissue. We also studied the allelic expression of the small nuclear ribonucleoprotein polypeptide N gene (SNRPN), which is reportedly maternally imprinted in humans, and compared the imprinting status with that of IGF2. Nine patients (45%) were heterozygous at the ApaI site of IGF2, nine (45%) were heterozygous at the possible AccII polymorphic site of SNRPN, and three (15%) showed polymorphism in both genes. The genomic DNA of 15 patients showed heterozygosity in either or both of these genes, and the mRNA of these was expressed monoallelically in myometrial tissues and leiomyomas of these patients. These results demonstrated that IGF2 and SNRPN imprinting is completely maintained in human uteri and leiomyomas and that increased expression of IGF2 is not due to biallelic expression.

Autoantigens↗
PubMed1996

Expression of oxytocin receptor in human pregnant myometrium.

Around the onset of labor, uterine sensitivity to oxytocin (OT) increases tremendously. Although this is considered to reflect OT receptor (OTR) augmentation in myometrium, neither spatial expression of OTR nor the level of the receptor message during the course of pregnancy have been investigated at the molecular level. We examined the localization and expression of the OTR in human myometrium by means of in situ hybridization, immunohistochemistry, and Northern and Western blotting. In the term pregnant myometrium, OTR expressing smooth muscle cells are observed diffusely and heterogeneously. Some of the smooth muscle cells were expressed high levels of the receptor at the messenger RNA and protein level, and they were surrounded with cells weakly positive for the OTR or negative. The level of OTR transcripts increased according to the course of pregnancy. The receptor messenger RNA level reached over 300-fold at parturition compared with the nonpregnant myometrium. In the myometrium at 32 weeks of gestation and not in labor, a relatively large amount (about 100-fold) of the receptor message was expressed. In the nonpregnant myometrium, significant amount of the receptor protein was revealed by Western blotting. We also found that the receptor protein was augmented at term and after the onset of labor. These findings indicated that the expression of OTR changes dynamically at the transcription and protein level during pregnancy and that its expression is heterogeneous in the term myometrium.

Amino Acid Sequence↗
PubMed1996

[Relation among lifestyle, social network, blood pressure and serum lipids in the elderly].

The relationships among seven lifestyle factors including stress, which is focused on as a risk factor for cardiovascular disease recently, social network, blood pressure and serum lipids in the elderly were examined in a cross sectional study of 85 males and 65 females aged 60 years or over in the city of Sayama, Saitama Prefecture. The seven lifestyle factors were as follows: (1) amount of alcohol consumption, (2) cigarette smoking, (3) Physical exercise, (4) sleeping time per night, (5) nutritional balance, (6) body weight, and (7) stress. As social network factors, marital status and coping factor for stress and/or anxiety were introduced. Stressful life events strongly associated with stress status were also discussed. In this study, it was clear that age, alcohol consumption, stress status and stressful life events caused higher blood pressure. On the other hand, the social network was associated with lifestyle status and a controlled blood pressure level. Obesity and physical exercise were significantly associated with serum lipids. There results suggest that it is very important for the maintenance and promotion of health and risk reduction of disease among the elderly to control socio-psychological factors such as stress and stressful life event, and that a social network helps maintain a healthy lifestyle.

Aged↗
PubMed1996

Postural control under clinorotation in upside-down catfish, Synodontis nigriventris.

The upside-down catfish Synodontis nigriventris has a unique habit of swimming and resting upside-down in free water. This behavior leads to the assumption that the catfish has a specific gravity information processing system. We examined the postural control behaviors in the catfish under clinorotation which is usually used for producing pseudo-microgravity. Synodontis nigriventris kept its body posture at a stable area of the rotated flask in which the catfish was kept, when it was clinorotated at the rate of 60 rpm. In contrast to Synodontis nigriventris, a related species, Corydoras paleatus, did not show such steady postural control. When the flask was rotated at a lower rate of 30 rpm or a higher rate of 100 rpm, Synodontis nigriventris as well as Corydoras paleatus showed a considerable disturbed control of body posture. In this condition, they were frequently rotated with the flask. These findings suggest that Synodontis nigriventris has a high ability to keep upside-down posture and the gravity sensation in this catfish is likely to contribute to its different postural control from that of many other fishes.

Animals↗
PubMed1996

[A case of ACTH-producing thymic carcinoid tumor with Cushing syndrome].

ACTH-producing thymic carcinoid tumor with Cushing syndrome in a 41-year-old male was reported. Plasma ACTH and cortisol was high, and chest X-ray film and CT scan revealed a tumor mass in the anterior mediastinum. Extended thymectomy with pretracheal lymph node dissection was performed. The microscopic findings revealed that the mass was carcinoid tumor with metastasis of anterior mediastinal lymph node. ACTH and cortisol were restored to normal range 1 week after operation. Unfortunately, he admitted seven months later because of high level of ACTH and right supraclavicular lymph nodes swelling. He underwent right neck dissection. Pathological examination proved metastatic carcinoid tumors in the dissected nodes. It is important to perform supraclavicular lymph node dissection together with extended thymectomy for thymic carcinoid tumor.

Adrenocorticotropic Hormone↗
PubMed1996

[Normal CBF values by the ARG method using IMP SPECT: comparison with a conventional microsphere model method].

N-isopropyl-p[123I]iodoamphetamine (IMP) has been used as a flow tracer for SPECT, and measurement of cerebral blood flow (CBF) using IMP has been performed by conventional microsphere model method (MS method). Recently, the ARG method for measuring CBF by using IMP with one SPECT scan and one point blood sampling has been developed. This method was based on two-compartment model. In the present study, normal CBF values were measured in ten male healthy subjects (mean age +/- S.D.: 29.8 +/- 6.01, age range: 23-41) by the ARG and the MS methods. The mean CBF values (+/- S.D.) for the ARG method in which the Vd value was assumed to be 50 ml/ml were 41.7 +/- 9.4, 31.1 +/- 5.0, 40.7 +/- 9.7, 41.5 +/- 10.0, 38.2 +/- 9.2, 39.0 +/- 9.4, 41.9 +/- 10.6, 38.7 +/- 8.0 and 30.0 +/- 7.7 ml/100 ml/min in the cerebellum, pons, thalamus, basal ganglia, frontal, temporal, parietal, occipital lobe cortex and centrum semiovale, respectively. The mean CBF values for the MS method were 46.8 +/- 8.4, 37.5 +/- 5.6, 45.8 +/- 8.6, 46.5 +/- 8.9, 43.7 +/- 8.3, 44.4 +/- 8.7, 46.8 +/- 9.3, 44.3 +/- 7.3 and 36.3 +/- 8.1 ml/100 ml/min, respectively. The mean CBF values in the cerebral cortex region for the ARG method were lower than those previously reported by PET. This would be caused by low first-pass extraction fraction of IMP compared with oxygen-15 labeled water. The mean CBF values for the MS method were higher than those for the ARG method against previous studies. As reasons for this, errors in estimation of the SPECT brain counts at 8 min in the MS method were considered.

Adult↗
PubMed1996

Hypoperfusion in the limbic system and prefrontal cortex in depression: SPECT with anatomic standardization technique.

UNLABELLED: Depression is a common psychiatric illness, and several reports have described cerebral blood flow (CBF) abnormalities on SPECT studies in affected patients. However, because region of interest analyses were used to determine significant CBF changes in these studies, there were methodological limitations. Therefore, we investigated CBF distribution abnormalities in depression on a pixel-by-pixel basis using SPECT and an anatomic standardization technique that has been commonly used for PET activation studies. METHODS: Eleven patients with unipolar depression, six patients with bipolar depression and nine age-matched normal control subjects underwent HMPAO brain SPECT studies. The radioactivities of SPECT images for each subject were globally normalized to 100 counts/pixel. Then, each SPECT image was transformed for standard brain anatomy using a computerized Human Brain Atlas system. For each group, the mean and variance images were calculated from the standardized anatomic SPECT images, and group comparisons were performed on a pixel-by-pixel basis. RESULTS: Significant decreases in CBF in the prefrontal cortices, limbic systems and paralimbic areas were observed in both depression groups compared with the normal control group. CONCLUSION: Decreases in CBF in these regions may be related to impaired attention as well as cognitive and emotional responses, which have been recognized as usual symptoms in depression. The anatomic standardization technique promises to be useful for group comparison analysis of brain SPECT on a pixel-by-pixel basis for individual neurological and psychiatric diseases.

Aged↗
PubMed1996

[Regional distribution of the muscarinic cholinergic receptor in the human brain studied with 11C-benztropine and PET using an anatomical standardization technique].

We measured regional distribution of the muscarinic cholinergic receptor in the normal human brain with 11C-benztropine (BZT) and positron emission tomography (PET) using an anatomical standardization technique. Seven normal volunteers who gave informed consents were involved in this study. Immediately after intravenous injection of 11C-BZT into the subjects, we started dynamic PET scanning and serial frequent arterial blood sampling. Analyses of plasma metabolites were also performed at selected time points and plasma time activity curves (TAC) of unmetabolized ligand were generated. From these PET and TAC data, we obtained Patlak plot slope calculation images. Using the HBA (human brain atlas) system, the Patlak plot slope calculation image of each subject was transformed into the shape of the standard brain. Mean and standard deviation (SD) calculation images were generated from those anatomically standardized images. On these mean and SD images, we placed regions of interest which were previously outlined on a MR image of the standard brain. From those data, we found the highest receptor distribution in the striatum and occipital cortex, as well as high distribution in the frontal, parietal, and temporal cortices, which were consistent with previous reports. These results suggested that anatomical standardization of PET receptor images with 11C-BZT will be useful for delineating the physiological or pathological alterations of the muscarinic cholinergic receptor in the human brain.

Adolescent↗
PubMed1996

[Normal cerebral perfusion of 99mTc-ECD brain SPECT--evaluation by an anatomical standardization technique].

A single photon emitter labeled tracer, 99mTc-ethyl cysteinate dimer (99mTc-ECD), has now been used for rCBF studies with SPECT. However, normal distribution pattern of this agent in the brain still remains unclear. Therefore, the specific purpose of this study was to investigate the normal distribution pattern of 99mTc-ECD SPECT image. Regional cerebral distribution was measured with SPECT and 984 +/- 17 MBq of 99mTc-ECD in ten normal subjects. During the SPECT measurement, subjects were placed comfortably in a supine position with their eyes closed. Each SPECT image was anatomically standardized using a computerized brain atlas system of Roland et al. (HBA: Human Brain Atlas) and X-CT image. Anatomically standardized SPECT images were globally normalized to 100 count/voxel. Then, the mean and SD images of brain SPECT were calculated voxel-by-voxel basis. The highest radioactivity was found in the medial aspect of the occipital lobe. The results indicate that the normal distribution pattern of 99mTc-ECD in the human brain may be not simply reflect the regional cerebral blood flow.

Adult↗
PubMed1996

Surface coverage of vascular grafts with cultured human endothelial cells from subcutaneous fat tissue obtained with a biopsy needle.

Surface coverage with autogeneous endothelial cells is effective in reducing thrombogenicity of an artificial vascular graft, but procedure for obtaining the cells is invasive for patients. The purpose of this study was to establish cultures of human endothelial cells separated from a small piece of subcutaneous fat tissue. A piece of tissue weighing about 10 mg was obtained from subcutaneous fat using a biopsy needle, and treated with collagenase and dispase. Microvascular endothelial cells were selected and other types of cells contaminating the cultures were eliminated by scraping with a needle under a microscope. The yield of the cells was 8362 +/- 4264/10 mg of subcutaneous fat (n = 7). The cultures reached confluence in about 2 weeks. The cells were positive for von Willebrand factor, P-selectin, and uptake of acetylated low density lipoprotein. The cells produced 15.9 +/- 3.3 ng/mg cell protein/h of 6-ketoprostaglandin F1 alpha (n = 5) when stimulated with thrombin. Thrombin also stimulated the production of platelet-activating factor: 7653 +/- 4297 dpm/10(6) cells (n = 5). Endothelin-1 accumulation in the medium of unstimulated endothelial cells was 0.54 +/- 0.16 ng/mg cell protein/10 h (n = 8). As a preliminary experiment for graft seeding, the cells were also cultured on pieces of a gelatin-coated Dacron graft, and scanning electron microscopy revealed the surface coverage of the graft. We herein described about successful culture of human microvascular endothelial cells from subcutaneous fat tissue obtained using a biopsy needle. The cultured cells may be applicable to a seeded vascular graft.

6-Ketoprostaglandin F1 alpha↗
PubMed1996

[Development of a new statistical evaluation method for brain SPECT images].

The purpose of this study was to develop a new statistical evaluation method for Brain SPECT images. First, we made normal brain image databases using 99mTc-ECD and SPECT in 10 normal subjects as described previously. Each SPECT images were globally normalized and anatomically standardized to the standard brain shape using Human Brain Atlas (HBA) of Roland et al. and each subject's X-CT. Then, mean and SD images were calculated voxel by voxel. For the next step, 99mTc-ECD SPECT images of a patient were obtained, and global normalizing and anatomical standardization were performed as the same way. Then, a statistical map was calculated as following voxel by voxel; (P-Mean)/SD x 10 + 50, where P, Mean and SD indicate voxel value of patient, mean and SD images of normal databases, respectively. We found this statistical map was helpful for clinical diagnosis of brain SPECT studies.

Brain↗
PubMed1996

The novel role of 3',5'-guanosine monophosphate (cGMP) on the differentiation of trophoblasts: comparison with the effects of 3',5'-adenosine monophosphate (cAMP).

We investigated the effects of 3',5'-guanosine monophosphate (cGMP) on the differentiation of human trophoblasts. Isolated cytotrophoblasts were cultured with 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) or 8-bromoadenosine 3'5-cyclic monophosphate (8-Br-cAMP) and then stained immunocytochemically with anti-human chorionic gonadotropin (anti-hCG) antibody to identify hCG expression as an index of differentiation. Concurrently, morphological changes from cytotrophoblasts to syncytiotrophoblasts were analyzed. Both 8-Br-cGMP and 8-Br-cAMP enhanced the expression of hCG in cultured cytotrophoblasts with the differentiation of cytotrophoblasts to syncytiotrophoblasts dose-dependently. With regard to trophoblast proliferation, 8-Br-cAMP but not 8-Br-cGMP enhanced [3H]thymidine uptake by these cells. hCG, a trophoblast-specific glycoprotein hormone has been identified as a potent growth factor for trophoblasts, also increased [3H]thymidine uptake and the intracellular 3',5'-adenosine monophosphate (cAMP) concentration. However, in this study, hCG did not increase the concentration of intracellular cGMP. We also showed that sodium nitroprusside (SNP), which is a donor of nitric oxide (NO), enhanced intracellular cGMP concentration. These results suggest that cGMP enhances trophoblast differentiation without affecting their proliferation, while cAMP enhances both differentiation and proliferation. We conclude that an alternative pathway mediated through cGMP is responsible for the differentiation of trophoblasts. NO may be involved in trophoblast differentiation with an increase in cellular cGMP level.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1995

Overexpressed tau protein in cultured cells is phosphorylated without formation of PHF: implication of phosphoprotein phosphatase involvement.

Pyramidal neurons in affected regions of Alzheimer's disease (AD) brain contain neurofibrillary tangles (NFT), aggregates of paired helical filaments (PHF) composed mainly of phosphorylated microtubule-associated protein tau. To explore the role of tau phosphorylation in the aggregation of tau into PHF, we constructed mammalian cell culture systems producing high levels of intracellular phosphorylated tau. COS-1 fibroblast-like cells were transiently transfected to simultaneously express tau, MAP kinase (MAPK), and MAP kinase kinase (MAPKK), or alternatively to express tau and glycogen synthase kinase 3 (GSK3). B103 neuron-like cells (which contain MAPK but little tau or GSK3) were stably transfected to express tau or tau and GSK3. In both systems, GSK3-transfected cells contained tau AT8/M (defined by AT8 staining and tau PHF-like mobility), but MAPK-transfected cells required phosphatase inhibitors, such as okadaic acid (OKA) or calyculin (CAL), to produce tau AT8/M. In vitro, the same concentrations of CAL and OKA inhibit phosphatases 1 and 2A (PP1 and PP2A), except that 100-1000 times as much OKA is needed to inhibit PP1. Inducing tau phosphorylation at the AT8 site in MAPK-transfected cells required 2-10 times more OKA than CAL, suggesting both PP1 and PP2A helped block the phosphorylation. Though levels of tau AT8/M reached 2-8% of total cellular proteins in COS-1 cells, the ratio of particulate to supernatant tau levels did not increase, and no tangles were observed; perhaps post-translational modifications or co-aggregating proteins are needed to induce PHF.

Animals↗
PubMed1995

Leukemia inhibitory factor (LIF) enhances trophoblast differentiation mediated by human chorionic gonadotropin (hCG).

We investigated the effect of LIF on the differentiation of trophoblasts. Isolated cytotrophoblasts were cultured with and without LIF and cell smears were immunocytochemically analyzed, using anti-hCG antibody. The percentage of differentiated trophoblasts stimulated by 10ng/ml of LIF was about 2.5-fold that in the control culture. The effect of LIF in inducing the differentiation of cytotrophoblasts to syncytiotrophoblasts was dose-dependent. The same effect was shown when hCG was added to the medium. This enhancing effect of LIF on trophoblast differentiation was blocked by adding anti-hCG antibody to the culture system. These results indicate that LIF enhanced trophoblast differentiation by stimulating hCG production in trophoblasts, and not by exerting a direct effect on the trophoblasts.

Abortion, Legal↗
PubMed1995

Activity in the human primary motor cortex related to arm and finger movements.

With the purpose of mapping representations of the finger and proximal arm in the human primary motor cortex (MI), we measured regional cerebral blood flow (rCBF) in eight right-handed normal volunteers during self-paced finger and proximal arm movements. Each movement activated two different fields in MI, one located deep in the anterior lip of the central sulcus and the other relatively close to the surface of the precentral gyrus. Arm fields were located higher than finger fields. A superficial arm field and a deep finger field partially, overlapped. The results indicate that there are two spatially separate motor representations of the finger and proximal arm in the human MI.

Adult↗
PubMed1995

Interleukin-1 receptor antagonist expression in epithelial cells of human endometrium.

OBJECTIVE: To examine the expression of interleukin-1 (IL-1) and IL-1 receptor antagonist (IL-1ra) in the human endometrium in the follicular and luteal phases. METHODS: The concentrations of IL-1alpha and IL-1beta in the culture supernatants of endometrial cells were determined by enzyme-linked immunosorbent assay. Transcription of the IL-1ra gene in the endometrium was investigated by reverse polymerase chain reaction (PCR). Human endometrium was immunohistochemically stained using a monoclonal antibody specific to IL-1ra. RESULTS: The concentrations of IL-1alpha and IL-1beta in the culture supernatants were 11 and 55 pg/ml, respectively, in the follicular phase, and 10 and 40 pg/ml, respectively, in the luteal phase. The concentration of IL-1ra was 465 pg/ml in the follicular phase and 1710 pg/ml in the luteal phase. Densitometric analysis of the reverse PCR products showed that the expression of IL-1ra mRNA was increased in endometrial cells in the luteal phase. Immunohistochemical staining revealed that epithelial cells were the main source of IL-1ra in human endometrium. CONCLUSIONS: Human endometrial cells produce IL-1 (mainly IL-1beta) and IL-1ra. The level of IL-1ra production in human endometrial epithelial cells was greater in the luteal phase than in the follicular phase due to the increased transcription of the IL-1ra gene.

Endometrium↗