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H Nakata

Publications and source records attributed to H Nakata.

At least 181 records · Page 10Linked to original sources
PubMed1993

Development of an antiserum to rat-brain A1 adenosine receptor: application for immunological and structural comparison of A1 adenosine receptors from various tissues and species.

An antiserum was developed in a rabbit against rat-brain A1 adenosine receptor. This antiserum recognized the denatured form of the purified rat-brain A1 adenosine receptor in immunoblot analysis and the native form of the receptor in the immunoprecipitation analysis. Immunoblot analysis of unpurified or purified adenosine receptor preparations from rat-brain membranes revealed a major immunoreactive band at a position of molecular mass of approx. 35 kDa, which corresponds to the position of purified rat-brain A1 adenosine receptor. Although A1 adenosine receptors from other rat tissues such as testis and adipocyte were also found to be immunoreactive with this antiserum by immunoblot analysis, purified human-brain A1 adenosine receptors showed a poor reactivity with this antibody. The order of the relative immunoreactivity of these A1 adenosine receptors with the antiserum was found to be brain > adipocyte > or = testis. Moreover, the immunoreactivity of these receptors significantly increased after these receptor preparations were deglycosylated by endoglycosidase F. After the deglycosylation, no significant differences in both the immunoreactivity and molecular mass among these receptor preparations were found on the immunoblot. These results suggest that the differences in the molecular mass or immunoreactivity among the A1 adenosine receptor preparations from three rat tissues were mainly due to the difference of sugar moiety present in each receptor molecule. These data are the first to provide analyses of immunological characteristics of A1 adenosine receptors from different tissues and species.

Adipose Tissue↗
PubMed1993

Characterization of gastrin/CCK receptors on gastric carcinoid tumor membrane of Mastomys natalensis.

Recently, we identified the specific binding site for gastrin on the gastric carcinoid tumor of Mastomys (Praomys) natalensis. In this study, precise characterization of the gastrin binding site on these tumors was performed. Both 125I-human gastrin I (gastrin) and 125I-CCK-8 bound specifically to the cell membrane, and Scatchard analysis revealed a high affinity binding site for each ligand with similar Kd and Bmax values. The specific binding of both 125I-gastrin and 125I-CCK-8 was displaced in a concentration-dependent manner by various related peptides with a relative potency order of CCK-8 > or = gastrin < des(SO3)CCK-8. In addition, L364,718 as well as L365,260 displaced the binding of both ligands with similar potencies. Furthermore, not only gastrin but also CCK-8 increased [Ca2+]i in these tumor cells, the action of both being inhibited by L364,718 as well as by L365,260 (10(-7) M). These results suggest that the carcinoid tumor of Mastomys possesses a high affinity gastrin/CCK binding site coupled to the increase of [Ca2+]i.

Animals↗
PubMed1993

Influence of usual intake of dietary caffeine on single-dose kinetics of theophylline in healthy human subjects.

The influence of usual multiple ingestions of dietary caffeine on oral single-dose pharmacokinetics of theophylline has been investigated in 6 healthy male subjects. The subjects consumed 2 to 7 cups of regular instant coffee during the 24 h study period. Their mean serum concentrations of caffeine varied from 1.2 to 3.1 mg/l. After their usual intake of dietary caffeine, the serum concentrations of theophylline from 3 to 24 h after administration were significantly higher than after deprivation of dietary caffeine. The apparent elimination of theophylline half-life was prolonged from 6.3 (0.61) h (mean with (SEM)) to 8.3 (0.47) h (32% increase, P < 0.01) and the total body clearance was reduced from 55.0 (1.31) ml.h-1.kg-1 to 42.5 (2.63) ml.h-1.kg-1 (23% decrease, P < 0.001). Saturation of theophylline metabolism and/or competition between theophylline and caffeine metabolism in addition to theophylline derived from caffeine may be the cause of the delayed elimination of theophylline. The present study has indicated that a significant reduction in theophylline metabolism may be caused by a conventional intake of dietary caffeine. In bronchodilator therapy with theophylline, therefore, the daily consumption of caffeine should be taken into consideration.

Administration, Oral↗
PubMed1993

Phosphorylation of muscarinic receptors: regulation by G proteins.

Effects of G proteins on the phosphorylation of muscarinic receptors (mAChRs) have been examined. Cerebral but not atrial mAChRs were phosphorylated by any one of three types of protein kinase C and 4-6 mol of phosphate were incorporated per mol of mAChR, mostly in the 12-14 kDa from the carboxyterminus. Atrial mAChRs were better substrates of cAMP-dependent protein kinase than cerebral mAChRs. Phosphorylation of mAChRs by protein kinase C or cAMP-dependent protein kinase was not dependent on the presence of agonists and G proteins except that a slight inhibition by G proteins was observed probably because G proteins were also substrates of the two kinases. Agonist-dependent phosphorylation of atrial mAChRs or recombinant human mAChRs (m2 subtype) by a kinase (mAChR kinase), which is the same or very similar to beta adrenergic receptor kinase (beta ARK), was found to be regulated by the G proteins in a dual manner; stimulation by G protein beta gamma subunits and inhibition by G protein alpha beta gamma trimer. The inhibition by the G protein trimer is restored by addition of guanine nucleotides and is considered to be due to the formation of a ternary complex of agonist, mAChR and guanine nucleotide free G proteins. The stimulation by G protein beta gamma subunits was also observed for the light- or agonist-dependent phosphorylation of rhodopsin and beta AR by the mAChR kinase but not for the light-dependent phosphorylation of rhodopsin by rhodopsin kinase. The phosphorylation by beta ARK 1 was also found to be stimulated by G protein beta gamma subunits. The beta gamma subunit is considered to interact with the extra 130 amino acid residue carboxyterminal tail of beta ARK, which does not exist in rhodopsin kinase, and the interaction results in the activation of the kinase. We may assume that the G protein coupled receptor kinase is an effector of G protein beta gamma subunits and that one of the functions of beta gamma subunits is to stimulate the phosphorylation of G protein coupled receptors thereby facilitating their desensitization.

Acetylcholine↗
PubMed1993

Alteration of lipoprotein(a) concentration with glycemic control in non-insulin-dependent diabetic subjects without diabetic complications.

Recently, a high plasma level of lipoprotein(a) [LP(a)] has been considered an independent risk factor for atherosclerosis and its sequelae, particularly myocardial infarction. Patients with non-insulin-dependent diabetes mellitus (NIDDM) have an increased mortality rate from cardiovascular and cerebrovascular disease. Therefore, plasma concentrations of Lp(a) were determined and the relationship between fasting plasma Lp(a) level and diabetic control was investigated in NIDDM patients without any diabetic complications. Fasting plasma Lp(a) levels were measured using enzyme-linked immunosorbent assay kits [Terumo Medical Corp, Elkton, MD, Lp(a)] in 61 NIDDM subjects (30 men aged 56 +/- 2.0 years, 31 women aged 53 +/- 2.1 years [mean +/- SEM]) who were without any diabetic macroangiopathy and microangiopathy such as retinopathy, nephropathy, and neuropathy and in 56 healthy age- and sex-matched controls. Plasma Lp(a) levels were significantly higher in the diabetic group than in the control group (23.5 +/- 2.5 v 11.7 +/- 1.4 mg/dL [mean +/- SEM], P < .001). There was no significant correlation between log-transformed plasma Lp(a) levels and other factors such as age, sex, body mass index (BMI), blood pressure, duration of diabetes, fasting plasma glucose (FPG) level, glycosylated hemoglobin (HbA1C) level, and plasma lipid levels except for low-density lipoprotein cholesterol (LDL-C) levels in diabetic patients. A significant positive correlation was noted in diabetic patients between the changes of log Lp(a) and HbA1C levels after a 3-month follow-up period (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1993

Antibodies raised against the adenosine receptor agonist, 5'-N-ethylcarboxamidoadenosine (NECA).

Antisera against the non-selective adenosine receptor agonist 5'-N-ethylcarboxamido-adenosine (NECA) have been raised by immunizing rabbits with NECA-coupled bovine serum albumin. The antisera which bind [3H]NECA with high affinity were purified by affinity chromatography using NECA-coupled Sepharose as the affinity gel without significant changes in [3H]NECA-binding properties. The order of the affinity for various adenosine receptor ligands of the purified or unpurified antisera was 5'-N-cyclopropylcarboxamidoadenosine > or = NECA > 2',5'-dideoxyadenosine > 2-chloroadenosine > theophylline > isobutylmethylxanthine > (R)-N6-phenylisopropyladenosine = N6-cyclohexyl- adenosine. This specificity was found to be similar to that of the non-receptor NECA-binding sites, which had been found in various tissues such as human placentas and mouse P815 mastocytoma cells, rather than to that of adenosine receptors. These anti-NECA antibodies will be useful as immunochemical agents in the search for endogenous ligand(s) to the non-receptor NECA-binding sites.

Adenosine↗
PubMed1993

Spiral volumetric CT as a routine technique for thoracic imaging.

The use of spiral volumetric computed tomography (CT) for thoracic imaging is described. A phantom experiment using nodules made of fish meat established a clinically acceptable practical table speed of 15 mm/s. With this table speed it was possible to scan the entire lung during a single breath-hold of 16-20 s. Comparison of this technique with conventional CT in 18 patients with 62 nodules showed no difference in effectiveness. The imaging of linear and reticular opacities, however, was not satisfactory in three of the eight lesions. Visualization of normal mediastinal vessels on spiral CT using less contrast material was comparable to that of conventional CT in 20 of 30 patients; it was less satisfactory in 10 patients, but vessels still could be identified. We conclude that spiral CT is a useful method to examine the thorax.

Humans↗
PubMed1993

Assessment of Chlamydia trachomatis-specific IgA and IgG serum antibodies in genitourinary Chlamydia trachomatis infection--comparative study between HITAZYME and IPAzyme.

We assessed the C. trachomatis antibody assay kit HITAZYME (Hitachi Chemical Co., Ltd.) using clinical specimens. This kit is based on an enzyme immunoassay (EIA) which utilized purified Chlamydia trachomatis outer membrane antigen as the solid phase antigen. Twenty-nine untreated male urethritis patients, 816 pregnant housewives, 188 cervicitis patients, and 76 pelvic inflammatory disease patients were tested. Agreement between the HITAZYME test and antigen detection in infected area was assessed, and a comparison was made with IPAzyme (a commercially available indirect immunoperoxidase assay kit). 1) Summary of HITAZYME and IPAzyme IgA: Agreement between the two assays was relatively good, i.e., 82.6% (916/1109). However, 5.5% (61/1109) were HITAZYME (-), IPAzyme (+), and 11.9% (132/1109) were HITAZYME (+), IPAzyme (-). Thus, in quite a few cases the results did not agree. IgG: Agreement between the two assays was 73.7% (817/1109). Agreement was relatively low, 24.4% (271/1109) were HITAZYME (-), IPAzyme (+). 2) In the cases of disagreement, more specific Western blot analysis was performed to check the reactivity of the anti-C. trachomatis antibody. When IgA was used, agreement between HITAZYME and Western blot analysis was 69.6% (16/23), and agreement between IPAzyme and Western blot analysis was 30.4% (7/23), whereas when IgG was used, agreement between HITAZYME and Western blot analysis was 80.0% (12/15), and agreement between IPAzyme and Western blot analysis was 20.0% (3/15). There was significantly greater agreement with HITAZYME than with IPAzyme. In other words, HITAZYME had greater specificity when reacted with C. trachomatis antigen than IPAzyme. 3) The IgA antibody-positive rate in antigen (+) cases (male urethritis: 72.7%, pregnant housewives: 65.7%, cervicitis: 70.3%, pelvic inflammatory disease: 70.0%) was significantly (p < 0.01) higher than in antigen (-) cases (male urethritis: 16.7%, pregnant housewives: 13.6%, cervicitis: 22.6%, pelvic inflammatory disease: 30.4%). Therefore, IgA antibody can serve as a suitable indicator for active infection. 4) The IgG antibody-positive rate in antigen (-) female cases was 15.5% using HITAZYME and significantly (p < 0.01) lower than with IPAzyme. HITAZYME had greater specificity than IPAzyme. In conclusion, HITAZYME has relatively good sensitivity and specificity. Moreover, since it is an EIA assay, it allows objective evaluation of results. It permits processing of a large number of specimens because it is easy to perform. Thus, HITAZYME is a superior antibody assay for C. trachomatis. It can be used when antigen tests are difficult to perform. It is strongly anticipated that HITAZYME will be able to be used clinically as a screening test.

Chlamydia Infections↗
PubMed1993

Human neuroblastoma cells express alpha and beta platelet-derived growth factor receptors coupling with neurotrophic and chemotactic signaling.

Both platelet-derived growth factor (PDGF) A- and B-chains are expressed in mammalian neurons, but their precise roles still remain to be clarified. In the present studies, we examined the expression of two PDGF receptor genes in human tumor cell lines derived from neural crest. The expression of alpha and/or beta PDGF receptors was detected in a wide variety of neural crest-derived human tumor cell lines such as neuroblastoma, primitive neuroectodermal tumor, and Ewing's sarcoma by RNA blot analysis, and confirmed by immunoblot analysis. We have also demonstrated that PDGF receptors on the human neuroblastoma cell lines were biologically functional. Accordingly, chemotactic and mitogenic activities were induced by either PDGF-AA or PDGF-BB in serum-free medium. PDGF isoforms as well as nerve growth factor induced morphological changes showing neuronal cell maturation. Moreover, PDGF coordinately increased the levels of the transcript of the midsize neurofilament gene. The neuroblastoma cell lines also expressed the transcripts of PDGF A- and B-chains. These findings suggest that PDGF isoforms are involved not only in the promotion of the neuroblastoma cell growth, but also in neuronal cell migration, growth, and differentiation in human brain development.

Amino Acid Sequence↗
PubMed1993

Primary low cerebrospinal fluid pressure syndrome associated with galactorrhea.

A 36-year-old woman with positional headache was found to have primary low cerebrospinal fluid (CSF) pressure syndrome and galactorrhea. The CSF pressure at lumbar puncture was not measurable. Magnetic resonance imaging demonstrated that the ventricle and cerebral sulcus were narrowed and the pituitary stalk was oppressed by the brain. Hyperresponsiveness of prolactin was noted after stimulation with thyrotropin-releasing hormone. These abnormalities disappeared with normalization of CSF pressure with the treatment. Galactorrhea was apparently due to oppression of the pituitary stalk by downward movement of the brain.

Adult↗
PubMed1993

Appearance of pulmonary metastases on high-resolution CT scans: comparison with histopathologic findings from autopsy specimens.

OBJECTIVE: The purpose of this study was to compare the appearance of pulmonary metastases on high-resolution CT scans with the histopathologic findings in lung specimens obtained at autopsy. The factors considered were the appearance of the margins of pulmonary metastases, the location of relatively small nodules in relation to the secondary pulmonary lobules, and the detectability of lymphangitic spread of tumors and intravascular tumor emboli on high-resolution CT scans. MATERIALS AND METHODS: We studied 14 lungs obtained at autopsy that contained metastatic lesions. We used both microscopy and high-resolution CT to evaluate 87 metastatic nodules 5-20 mm in diameter for the appearance of their margins and to determine the location of 43 nodules that were less than 5 mm in diameter relative to the secondary pulmonary lobules. The detection of histologically confirmed intravascular tumor emboli and lymphangitic spread by high-resolution CT also was evaluated. RESULTS: On high-resolution CT scans, 38% of the nodules had well-defined, smooth margins, 16% had well-defined, irregular margins, 16% had poorly defined, smooth margins, and 30% had poorly defined, irregular margins. The well-defined, smooth margins on high-resolution CT scans corresponded histologically to an expanding type and to an alveolar space-filling type; the poorly defined margins, to an alveolar cell type; and the irregular margins, to an interstitial proliferative type. Some correlation was found between the histologic type of primary tumor and the CT appearance of the lesion's margins. As for small nodules, 12% were connected with the central bronchovascular bundle, 28% were on the perilobular structures, and 60% were apparently not in contact with these structures. Only two of the 11 lungs with histopathologically confirmed lymphangitic tumor spread and none of the tumor emboli were detected on high-resolution CT scans. CONCLUSION: The characteristics of the margins of metastatic pulmonary nodules noted on histopathologic examination correlated well with their high-resolution CT findings. Microscopic intravascular tumor emboli and lymphangitic tumor spread were difficult to detect on high-resolution CT scans, indicating a limitation of high-resolution CT in the diagnosis of pulmonary metastatic disease.

Aged↗
PubMed1993

Effects of apolipoprotein E polymorphism on plasma lipoprotein(a) levels.

Effects of apolipoprotein E (apo E) genetic polymorphism on plasma lipoprotein(a) (Lp(a)) levels were investigated in 305 civil service workers (158 men and 147 women). Plasma Lp(a) levels were measured by ELISA. Apo E phenotypes were determined from plasma by isoelectric focusing, Western blotting and immunostaining, as we previously reported. A total of 305 subjects were divided into the three apo E groups; apo E2 group (n = 19 for apo E3/2 and n = 4 for apo E4/2), Apo E3/3 group (n = 224) and apo E4/3 group (n = 58). Mean levels of plasma Lp(a) were 14.2 mg/dl. Plasma Lp(a) levels were significantly lower in the apo E2 group (6.6 mg/dl) than in the apo E3/3 (15.1 mg/dl) and E4/3 (13.7 mg/dl) groups. Plasma total cholesterol (T-chol) and low density lipoprotein (LDL)-chol levels were significantly lower in the apo E2 group than in the apo E4/3 group and tended to be highest in the apo E4/3 group. A significant positive correlation was noted between plasma Lp(a) levels and plasma LDL-chol levels, indicating that the effects of apo E polymorphism on plasma Lp(a) levels were parallel to its effects on plasma LDL-chol levels. In women plasma Lp(a) levels were significantly lower in the apo E2 group than in the apo E3/3 and E4/3 groups, whereas in men plasma Lp(a) levels tended to be lower in the apo E2 group but no significant difference was noted among the three apo E groups. It is concluded that plasma Lp(a) levels are, at least in part, modulated by apo E polymorphism (particularly apo E2) and that there is a gender difference in the effects of apo E polymorphism on plasma Lp(a) levels.

Adult↗
PubMed1993

[Bone mineral loss in patients with chronic obstructive pulmonary disease].

Body weight loss is often observed in patients with chronic obstructive pulmonary disease (COPD). Bone mineral loss has also been reported in COPD, but the mechanisms are not well determined. To elucidate what factors influence on bone mineral content in COPD patients, we measured bone mineral content (BMC) by dual energy X-ray absorptiometry (DXA) (XR-26, Norland), pulmonary function, and ten minute walk distance (TMD) in Japanese elderly male patients with COPD. The subjects were 21 male patients with COPD (72.6 +/- 9.5 years) and 18 age-matched male normal individuals (66.5 +/- 9.5 years). COPD patients showed significantly (p < 0.05) lower BMC (1.82 +/- 0.33, 2.27 +/- 0.35 kg, respectively) compared with age-matched controls. BMC was significantly correlated with body weight and TMD (r = 0.71, r = 0.51, respectively). These results demonstrate that lower body weight and decreased exercise capacity account for the significantly lower bone mineral content of our COPD patients and that COPD patients with body weight loss may be at high risk for osteoporotic fracture.

Absorptiometry, Photon↗
PubMed1993

Gastrin/CCK-B receptors on brain, gastric parietal cells and ECL carcinoid tumor of Mastomys natalensis.

Cholecystokinin (CCK)-8 and human gastrin I (gastrin) were found to be almost equipotent in displacing the specific binding of not only 125I-CCK-8 but also 125I-gastrin to both ECL carcinoid tumor and parietal cell membranes of Mastomys natalensis. These binding specificities of the native gastrin receptors for CCK-8 and gastrin were identical to that of the cloned gastrin receptor from the ECL carcinoid tumor expressed on CHO-K1 cells. In contrast, CCK-8 was approximately 10-20 times as potent as gastrin in inhibiting the binding of the two radioligands to the Mastomys brain membrane. However, the nucleotide sequences of RT-PCR products of mRNAs extracted from not only the isolated parietal cells but also the brain were identical to that of the gastrin receptor cDNA from the ECL carcinoid tumor. Thus, the gastrin receptors on the parietal cells and the brain appear to be encoded by the same gene as those on the ECL carcinoid tumor in Mastomys. The reason for the difference in binding characteristics between the cloned gastrin receptor and the native gastrin/CCK-B receptor in the brain remains to be elucidated.

Animals↗
PubMed1993

[A case of spontaneous pneumothorax due to rupture of bleb infected with aspergillosis].

A 17-year-old male was diagnosed as having left spontaneous pneumothorax by chest X-ray. Chest CT scan showed a cystic shadow with a thick wall in the left apex. Thoracotomy was performed, and the bleb was resected. Histologically, aspergillus was found in the cavity and the wall of the resected bleb. In this case, we consider that focal aspergillus infection in the bleb caused spontaneous pneumothorax. In cases of spontaneous pneumothorax in which the bleb wall is thick, the bleb should be evaluated by histological and bacteriological examination. Such a case has been rarely reported in Japan.

Adolescent↗
PubMed1993

[Serum superoxide dismutase (SOD) activity in diabetes mellitus].

The serum superoxide dismutase (s-SOD) activities in patients with diabetes mellitus (DM) were assayed in order to evaluate its usefulness for monitoring of DM and also evaluate the relation between s-SOD activities and microangiopathies (nephropathy, neuropathy and retinopathy). As results followings were obtained; 1) s-SOD activities in DM patients were significantly higher than those in healthy controls (12.56 +/- 7.73 vs 10.51 +/- 1.69, p < 0.01). 2) There was no relations between s-SOD activities and FBS-, fructosamine- and HbA1-levels, respectively. 3) Among DM patients s-SOD activities were significantly higher in patients with microangiopathy than those in patients without microangiopathy (14.18 +/- 11.00 vs 11.24 +/- 3.13, p < 0.01). 4) Among DM patients with microangiopathy higher s-SOD activities tended to be observed in patients with triopathy such as nephropathy, neuropathy and retinopathy than in those with one or two microangiopathic complications. 5) Among DM patients with nephropathy the correlation was present between s-SOD activities and levels of creatinine. These results suggest that the assay of s-SOD activity is not useful for the monitoring of DM, however, it is suggested that the high s-SOD activity reflects the microangiopathic complications, particularly nephropathy.

Adult↗
PubMed1993

[A case of extraskeletal Ewing's sarcoma of the chest wall].

A 22-year-old woman was admitted to our hospital complaining of high fever, dyspnea and wheeze. Chest X-ray film and CT scan showed a huge mass lesion in the right chest. Histological findings of specimens obtained by both needle biopsy and surgery showed necrotic tissue. She died of rapidly progressive pulmonary metastasis three months after surgery, and at autopsy, the tumor was diagnosed as extraskeletal Ewing's sarcoma originating from the chest wall.

Adult↗