Search PubMed⌕ Search

Biomedical subjects

H Nakata

Publications and source records attributed to H Nakata.

At least 217 records · Page 12Linked to original sources
PubMed1991

Interleukin-1 enhances the response of osteoblasts to platelet-derived growth factor through the alpha receptor-specific up-regulation.

Both platelet-derived growth factor (PDGF) and interleukin-1 (IL-1) are produced by activated macrophages and are thought to contribute to bone remodeling, but their precise roles remain to be clarified. The interaction between PDGF and IL-1 was, therefore, studied in normal osteoblast-like cells (MC3T3-E1). The expression of alpha- and beta-PDGF receptors on MC3T3-E1 cells was detected by RNA blot analysis and confirmed by immunoblot analysis. PDGF-induced chemotactic as well as mitogenic activities were synergistically enhanced by either IL-1 alpha or IL-1 beta (40 units/ml) pretreatment in serum-free medium, although IL-1 alone did not show any detectable chemotactic activities. This biological enhancement by IL-1 was accompanied by a selective increase of alpha-PDGF receptor expression, following the augmentation of alpha receptor autophosphorylation and inositol phosphate hydrolysis induced by PDGF-AA. These findings suggest that PDGF and IL-1 are jointly involved in the bone-remodeling microenvironment as local coupling factors.

Blotting, Northern↗
PubMed1991

[Radiological diagnosis of splenic metastasis and its prevalence at autopsy].

CT and US findings of 7 cases of splenic metastases are described and the prevalence of splenic metastases at autopsy in 641 cases with malignant tumors were evaluated. Metastatic foci in spleen appeared mostly as poorly-defined low density masses on CT. Iodinated contrast material was administered in 2 cases, but no contrast enhancement was observed. US showed both hypoechoic and hyperechoic patterns. These appearances were nonspecific, but were similar to those of metastatic lesions in the liver which were often visible on CT associated with splenic metastases. At autopsy splenic metastases were found in 34 of 641 cases (5.3%). Gastric, colon, lung and ovarian cancers were most common primary tumors. However, the rate of splenic metastasis per tumor was highest in ovarian cancer (50.0%), followed by malignant melanoma (33.3%), colon cancer (16.2%) and gastric cancer (8.2%). Hepatoma which had the biggest number of autopsy cases in this series showed the lowest rate of splenic metastasis (0.8%).

Aged↗
PubMed1991

Presence of histamine H2-receptors on human gastric carcinoma cell line MKN-45 and their increase by retinoic acid treatment.

Histamine dose-dependently stimulated cyclic AMP production in human gastric carcinoma cell line MKN-45, and this effect was inhibited by cimetidine but not by pyrilamine. Moreover, not only histamine but also cimetidine displaced the specific binding of [3H]tiotidine to these cells, whereas pyrilamine had no effect. On the other hand, pretreatment of MKN-45 cells with retinoic acid (RA) significantly enhanced histamine-induced increase of cyclic AMP production, although the cyclic AMP response to either forskolin or NaF was not affected. Finally, RA treatment increased the number of histamine receptor without altering its affinity. Thus, it appears that histamine H2-receptors are present on MKN-45 cells, and that RA treatment enhances the action of histamine on these cells by increasing the number of H2-receptors.

Binding, Competitive↗
PubMed1991

Functional variations in parenchymal microvascular systems within the brain.

Variations in microvascular system functions were observed among a number of brain areas. The rates of local blood flow varied 18-fold among areas and were extremely high in neuroendocrine structures. Marked differences in blood flow were also found within some brain structures. The volume of radiolabeled blood in perfused parenchymal microvessels ranged from 5 to 70 microliters/g and correlated closely with local cerebral blood flow. The hematocrits within parenchymal microvessels were 45-75% of the arterial hematocrit, which indicates that red cells more rapidly traverse brain microvessels than do plasma proteins. The mean transit times of blood through parenchymal microvessels were extremely short and ranged from 0.3 to 0.6 s.

Animals↗
PubMed1991

The effects of chronic serum sickness on albumin distribution and glucose utilization in rat brain.

The level of cerebrospinal fluid (CSF) protein is elevated in diseases and disease models that are associated with circulating immune complexes such as serum sickness. Circulatory immune complexes are known to deposit in the basal lamina of fenestrated capillaries and may, as a result, affect both capillary bed and parenchymal function. Since the brain has both fenestrated and unfenestrated capillaries and immune complexes deposit to a varying extent in the fenestrated capillaries in chronic serum sickness, cerebral capillary permeability to protein may be altered in some brain areas and lead to the elevation of CSF proteins. In addition various other cerebrovascular and metabolic functions may also be affected by this condition. In this study either radio-iodinated serum albumin (RISA) or 2-[14C]deoxyglucose (14C-2DG) was intravenously injected into control Wistar rats and Wistar rats with chronic serum sickness; subsequently the tissue levels of radioactivity were measured by quantitative autoradiography in 4 brain areas with fenestrated capillaries and 11 brain areas with unfenestrated capillaries. The 2-min distribution of RISA, which demarcates the volume of circulating plasma in perfused microvessels and is generally proportional to local plasma flow, was the same in control and experimental rats. The passage of RISA from blood into brain over 30 min was negligible in both groups; thus cerebral capillary permeability to albumin was not detectably increased in any of these 15 brain areas by chronic serum sickness. The rate of local cerebral glucose utilization, an indicator of local metabolic and neural activity, was calculated from the 14C-2DG data and was virtually identical in control and experimental rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1991

Pulmonary hemorrhage in patients with systemic lupus erythematosus.

Five patients with pulmonary hemorrhage associated with SLE were studied. Chest radiographs showed extensive alveolar opacity immediately after hemoptysis or dyspnea in four patients. In one patient an interstitial pattern seen initially progressed rapidly to an alveolar pattern. Three patients were successfully treated with corticosteroids and are doing well at present. The diagnosis and treatment of pulmonary hemorrhage is vital to patients with SLE. In the appropriate clinical setting chest radiographic findings of acute alveolar disease should suggest pulmonary hemorrhage, and empiric treatment with corticosteroids should be considered.

Adolescent↗
PubMed1991

Transvaginal color and pulsed Doppler ultrasound evidence of hemodynamics of the female pelvis.

Transvaginal color and pulsed Doppler ultrasound examinations were made on 40 patients to assess hemodynamics in the pelvis. Use of a special probe for transvaginal scanning led to superb simultaneous visualization of structures and blood flow, and we noted various events, even in the small, deep and/or peripheral vessels. Some but not all of the observations were in agreement with the results obtained using transabdominal color and pulsed Doppler ultrasound. We propose that transvaginal color and pulsed Doppler ultrasound be considered for routine use to determine physiological and pathological events in the female pelvis.

Color↗
PubMed1991

Detection and identification of loline and its analogues in horse urine.

Several kinds of loline-type alkaloids, norloline, loline, N-acetylnorloline, N-acetylloline, N-formylnorloline, N-formylloline and N-methylloline were detected in the urine of race-horses. Furthermore, a new compound of the alkaloids, N-senecioylnorloline, was also found and identified. These compounds were mainly identified by means of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-fourier transform-infrared spectrometry (GC-FT-IR). A certain plant of Gramineae containing four kinds of loline-type alkaloids was found in a bale of hay used for the horse forage. The taxonomic feature of the plant was different from known plants containing loline-type alkaloids. The common fragmentation of loline-type alkaloids under electron ionization was briefly discussed.

Alkaloids↗
PubMed1991

The effect of furosemide on the endocochlear potential in ears with experimentally induced endolymphatic hydrops.

The endocochlear potential (EP) was measured in 38 guinea pigs with experimentally induced endolymphatic hydrops at the 3rd, 6th, 12th and 24th postoperative weeks, and the effects of furosemide (FUR, 50 or 80 mg/kg) on the EP were examined. A time-related reduction of the EP from the normal value and increased susceptibility to FUR were disclosed in the hydropic animals. Furthermore, 24-week animals given 80 mg/kg FUR showed a significantly slower recovery rate of the EP than the other groups, indicating impairment of the strial function progressive with post-operative time. The negative component of the EP was considered to be unimpaired until at least 12 weeks after the surgery.

Animals↗
PubMed1991

Cloning and expression of an A1 adenosine receptor from rat brain.

We have used the polymerase chain reaction technique to selectively amplify guanine nucleotide-binding regulatory protein (G protein)-coupled receptor cDNA sequences from rat striatal mRNA, using sets of highly degenerate primers derived from transmembrane sequences of previously cloned G protein-coupled receptors. A novel cDNA fragment was identified, which exhibits considerable homology to various members of the G protein-coupled receptor family. This fragment was used to isolate a full-length cDNA from a rat striatal library. A 2.2-kilobase clone was obtained that encodes a protein of 326 amino acids with seven transmembrane domains, as predicted by hydropathy analysis. Stably transfected mouse A9-L cells and Chinese hamster ovary cells that expressed mRNA for this clone were screened with putative receptor ligands. Saturable and specific binding sites for the A1 adenosine antagonist [3H]-1,3-dipropyl-8-cyclopentylxanthine were identified on membranes from transfected cells. The rank order of potency and affinities of various adenosine agonist and antagonist ligands confirmed the identity of this cDNA clone as an A1 adenosine receptor. The high affinity binding of A1 adenosine agonists was shown to be sensitive to the nonhydrolyzable GTP analog guanylyl-5'-imidodiphosphate. In adenylyl cyclase assays, adenosine agonists inhibited forskolin-stimulated cAMP production by greater than 50%, in a pharmacologically specific fashion. Northern blot and in situ hybridization analyses of receptor mRNA in brain tissues revealed two transcripts of 5.6 and 3.1 kilobases, both of which were abundant in cortex, cerebellum, hippocampus, and thalamus, with lower levels in olfactory bulb, striatum, mesencephalon, and retina. These regional distribution data are in good agreement with previous receptor autoradiographic studies involving the A1 adenosine receptor. We conclude that we have cloned a cDNA encoding an A1 adenosine receptor linked to the inhibition of adenylyl cyclase activity.

Amino Acid Sequence↗
PubMed1991

MR imaging of adult glomerulocystic kidney disease. A case report.

A 59-year-old man with hypertension and severe renal dysfunction was diagnosed as having adult glomerulocystic kidney disease. MR imaging of the kidney showed a diffuse reduction of the intensity of the renal cortex with a loss of normal cortico-medullary differentiation on T1-weighted images. Numerous small cortical cysts were also demonstrated. These MR findings complemented the results of the biopsy and were useful for making a definitive diagnosis.

Humans↗
PubMed1990

[Radiation therapy and diagnosis of primary malignant lymphoma of the brain].

CT findings and the results of radiotherapy were retrospectively evaluated on 11 patients with primary malignant lymphoma of the brain treated at UOEH Hospital from November, 1979 to March, 1989. CT mostly showed an isodensity or slightly high-density round masses with marked contrast enhancement and was useful both for an initial diagnosis and an evaluation of the response following treatment. Radiation therapy was given to the whole brain in 9 patients. Two patients were irradiated only locally to the tumor bearing area, but no long-term effect was observed. The total dosage ranged from 30 to 51.2 Gy. The 8 patients who received 50 Gy or more to the tumors had higher survival and local control rates than the other 3 who received less than 40 Gy. We conclude that whole brain irradiation with at least a total dose of 50 Gy to the tumor area is necessary to control malignant lymphoma of the brain.

Adult↗
PubMed1990

A1 adenosine receptor of rat testis membranes. Purification and partial characterization.

Purification of an A1 adenosine receptor of rat testes was performed using a newly developed affinity chromatography system (Nakata, H. (1989) Mol. Pharmacol. 35, 780-786). The A1 adenosine receptor was solubilized with digitonin from rat testicular membranes and then purified more than 25,000-fold by sequential use of affinity chromatography on xanthine amine congener-immobilized agarose, hydroxylapatite chromatography, re-affinity chromatography on xanthine amine congener-agarose, and finally gel permeation chromatography on TSK-3000SW. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the final preparation showed a single broad band of Mr 41,000 by autoradiography after radioiodination. This Mr 41,000 peptide was also specifically labeled with an A1 adenosine receptor affinity labeling reagent. A high affinity A1 adenosine receptor antagonist, 8-cyclopentyl-1,3-[3H]dipropylxanthine, bound saturably to the purified receptor with a KD of approximately 1.4 nM. The purified receptor also showed essentially the same specificity for adenosine agonists and antagonists as the unpurified receptor preparations, although the affinities of the purified adenosine receptor for agonists were significantly low compared to those of unpurified receptor preparations indicating that the purified A1 adenosine receptor exists as a low agonist-high antagonist affinity state. Deglycosylation of the purified testis adenosine A1 receptors with endoglycosidase F produced an increase in the mobility of the receptor protein to an apparent Mr 30,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, similar to that of deglycosylated A1 adenosine receptors of rat brain membranes. Peptide maps of the purified testis and brain A1 adenosine receptors using trypsin and V8 protease suggest that these receptors show some structural homologies.

Animals↗
PubMed1990

Quantitative autoradiographic assessment of 55Fe-RBC distribution in rat brain.

A simple in vivo technique of labeling erythrocytes (RBCs) with 55Fe was developed for quantitative autoradiography (QAR). This procedure involved injecting 5-6 ml of [55Fe]ferrous citrate solution (1 mCi/ml) intraperitoneally into donor rats. The number of labeled RBCs reached a maximum at around 7 days and declined very slowly thereafter. Labeled RBCs were harvested from donor rats and used for RBC volume measurement in awake rats. Brain radioactivity was assayed by QAR, which yielded spatial resolution of greater than 50 microns. Tight nearly irreversible binding of 55Fe to RBCs was found in vivo and in vitro. More than 99.5% of the 55Fe in the blood of donor rats was bound to RBCs. Because of this, labeled blood can be taken from donors and injected into recipients without further preparation. The tissue absorption of 55Fe emissions was the same in gray and white matter. Microvascular RBC volumes measured with 55Fe-labeled RBCs agreed with those assayed with 51Cr-labeled RBCs for many, but not all, brain areas. In conclusion, 55Fe-RBCs can be readily prepared by this technique and accurately quantitated in brain tissue by QAR.

Animals↗