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Biomedical subjects

M Mukoyama

Publications and source records attributed to M Mukoyama.

At least 109 records · Page 6Linked to original sources
PubMed1990

Pro-thyrotropin-releasing hormone concentrations in the brain of ataxic mice.

Concentrations of pro-thyrotropin-releasing hormone (pro-TRH) were studied in the brain of the Weaver ataxic mouse, the Purkinje cell degenerative mouse (pcd-ataxic mouse), the Staggerer ataxic mouse and the C3H mouse. The brain tissue was dissected into 7 parts, e.g., hypothalamus, cerebrum, thalamus, striatum, brain stem, cerebellum and cervical spinal cord. Pro-TRH concentrations in each part of the brain were measured by radioimmunoassay. Pro-TRH concentrations in the brain of Weaver ataxic mice, pcd-ataxic mice and Staggerer ataxic mice were significantly higher in the thalamus, brain stem, cerebellum and cervical spinal cord. Pro-TRH concentrations in the hypothalamus, striatum and cerebrum of ataxic mice did not differ from those of controls. The elution profile of acetic acid extracted cerebellum of ataxic mice on Sephadex G-50 was identical to that of synthetic pro-TRH. These findings suggest that changes in pro-TRH concentrations in the brain may play a pathophysiological role in ataxic mice.

Animals↗
PubMed1990

Determination of manganese concentrations in the spinal cords from amyotrophic lateral sclerosis patients by inductively coupled plasma emission spectroscopy.

Continuing analytical studies on environmental factors in the foci of amyotrophic lateral sclerosis (ALS) in the Kii Peninsula of Japan and Guam, and metal analysis using neutron activation analysis in central nervous system (CNS) tissues from ALS cases indicate that chronic exposure to metals such as aluminum and manganese, together with a deficiency of minerals such as calcium and magnesium, may play a causative role in the neurodegeneration seen in ALS. An accurate and simple method for detecting minerals and trace metals in small, fresh samples of CNS tissue is necessary in order to follow the pathogenetic behavior of these elements. In this paper, we describe a method for measuring manganese (Mn) content in CNS tissue samples taken from mouse brain using inductively coupled plasma (ICP) spectroscopy and present results of the determination of Mn contents in spinal cord samples from ALS cases using the same method. ICP emission spectroscopy is considered to have great advantage for the simultaneous determination of elements in small, fresh CNS samples because of its simplicity and convenience, and the elimination of the necessity to use potentially dangerous acids. Results showed that the mean concentration of Mn in a mouse brain (0.56 microgram/g) and in human spinal cords (0.39 microgram/g wet weight in the anterior horn, 0.37 in the lateral fasciculus, 0.39 in the posterior horn and 0.28 in the posterior fasciculus) were compatible with results previously reported using other methods. In ALS spinal cords, the mean content of Mn was similar to that of controls, but the distribution differed. In the ALS cases, Mn contents were higher in the anterior horn and lateral fasciculus than in the posterior horn.(ABSTRACT TRUNCATED AT 250 WORDS)

Amyotrophic Lateral Sclerosis↗
PubMed1990

Appearance of atrial natriuretic peptide in the ventricles in patients with myocardial infarction.

To study whether atrial natriuretic peptide (ANP) is present in the ventricles in patients with myocardial infarction, we have examined ventricular tissues from five patients with myocardial infarction and five control subjects without cardiovascular diseases by the indirect immunoperoxidase method using monoclonal antibody to alpha-human ANP. Immunoreactivity for ANP was observed in the subendocardial cardiac cells of infarcted as well as noninfarcted segments of the left ventricles in all patients with myocardial infarction. In a case of biventricular infarcts, the subendocardial cardiac cells of the right ventricle were also stained. In a case of ventricular aneurysm, the viable hypertrophied cardiac cells were immunoreactive for ANP throughout the wall of the aneurysm. Immunoreactivity for ANP, however, was not detected in the working ventricular cardiac cells in any of the control subjects. Because ANP improves left ventricular function by reducing both preload and afterload, the appearance of ANP in the ventricles in patients with myocardial infarction may be one of the manifestations of the compensatory mechanism.

Aged↗
PubMed1990

Magnesium concentration in brains from multiple sclerosis patients.

Magnesium (Mg) concentrations were studied in the brains of 4 patients with definite multiple sclerosis (MS) and 5 controls. The magnesium contents were determined by inductively coupled plasma emission spectrometry in autopsy samples taken from 26 sites of central nervous system tissues, and visceral organs such as liver, spleen, kidney, heart and lung. The average Mg content in the CNS tissues, as well as visceral organs except for spleen, of MS patients showed a significantly lower value than that seen in control cases. The most marked reduction of Mg content was observed in CNS white matter including demyelinated plaques of MS samples. Whether or not these significantly lower Mg contents found in CNS and visceral organs of MS patients may play an essential role in the demyelinating process remain unclear, requiring further studies on MS pathogenesis from the point of metal metabolism.

Adult↗
PubMed1990

Application of monoclonal antibodies for endothelin to hypertensive research.

We developed six kinds of monoclonal antibodies against endothelin (ET)-1 recognizing different epitopes with high affinities (5 x 10(10) M-1 to 5 x 10(11) M-1). Using these monoclonal antibodies, we developed radioimmunoassays for ET-1 with different specificities. Cross-reactivities with ET-2 ranged from 80% to 100%, and those with ET-3 ranged from 3% to 60%. Patients with essential hypertension (n = 20) showed a significant elevation in the plasma ET-1-LI level compared with age-matched control subjects (n = 12) (30.1 +/- 1.4 pg/ml versus 18.5 +/- 0.9 pg/ml, p less than 0.01). The plasma ET-1-LI level in hypertensive patients in stages II and III (World Health Organization classification) was significantly higher than that in those patients in stage I. There was no significant correlation between the plasma ET-1-LI level and systolic blood pressure (r = 0.11), diastolic blood pressure (r = -0.13), or age (r = 0.24) in all patients studied who had essential hypertension. In the neutralization experiment, monoclonal antibodies attenuated ET-1-induced contraction of rat aortic rings and the pressor action of ET-1 in pithed rats in vivo. The present study demonstrates the elevated plasma ET-1-LI level in patients with essential hypertension. Monoclonal antibodies developed in this study can become powerful tools to investigate the pathophysiological significance of ET in essential hypertension.

Animals↗
PubMed1990

Rat brain natriuretic peptide. Isolation from rat heart and tissue distribution.

We have isolated a cardiac natriuretic peptide of 5,000 d from atrial tissues from 500 rats and determined its amino acid sequence. The 5,000 d atrial natriuretic factor was elucidated to be a 45 amino acid peptide with the sequence of S-Q-D-S-A-F-R-I-Q-E-R-L-R-N-S-K-M- A-H-S-S-S-C-F-G-Q-K-I-D-R-I-G-A-V-S-R-L-G-C-D-G-L-R-L-F by sequencing the native peptide and its lysyl endopeptidase digests. The sequence of this peptide was identical to the amino acid sequence (51-95) of the rat brain natriuretic peptide precursor deduced from the complementary DNA (cDNA) sequence. The cardiac natriuretic peptide with a molecular weight of 5,000, or rat brain natriuretic peptide, was identified as the major storage form and as the sole secretory form derived from the brain natriuretic peptide precursor in the rat heart. The rat brain natriuretic peptide level in the atrium was 3.68 +/- 0.61 micrograms/g, which represents about 4% of that of atrial natriuretic factor. Rat brain natriuretic peptide was also detected in the ventricle. The ratio of brain natriuretic peptide to atrial natriuretic peptide in the ventricle was approximately 30% and much higher than that in the atrium. Rat brain natriuretic peptide, however, was not detectable in the brain. We conclude that the 5,000 d cardiac natriuretic peptide is rat brain natriuretic peptide with 45 amino acids derived from the brain natriuretic peptide precursor and is secreted from the rat heart as a novel cardiac hormone.

Amino Acid Sequence↗
PubMed1990

Rat brain natriuretic peptide--tissue distribution and molecular form.

Using an antiserum against the ring structure of rat brain natriuretic peptide (rat BNP), we have established a specific radioimmunoassay (RIA) for rat BNP and elucidated its tissue distribution and molecular form. Rat BNP-like immunoreactivity (-LI) was detected in the highest amount in cardiac extracts (574.0 +/- 138.8 pmol/g in the atrium and 4.3 +/- 1.1 pmol/g in the ventricle). The secretory rate of rat BNP-LI from the perfused whole heart was 50.0 +/- 1.9 fmol/min, about 60% of which was maintained even after atrial removal. We also detected rat BNP-LI throughout the spinal cord (134-175 fmol/g), although no detectable amount was present (less than 100 fmol/g) in other tissues including the brain. High performance-gel permeation chromatography and reverse phase-high performance liquid chromatography coupled with the RIA revealed that rat BNP with 45 amino acids is a major storage form as well as a secretory form of rat BNP-LI in the heart. The major component in the spinal cord was also rat BNP. These findings indicate that the tissue distribution and the processing pattern of rat BNP are different from those of atrial natriuretic peptide and porcine BNP, thereby suggesting the presence of complicated diversity of the natriuretic peptide system.

Animals↗
PubMed1990

Preparation of monoclonal antibodies against brain natriuretic peptide and their application to radioimmunoassay and passive immunization.

Two monoclonal antibodies (mAbs) directed toward brain natriuretic peptide (BNP), KY-BNP-I and KY-BNP-II, have been produced. Both mAbs against BNP possessed high affinities for BNP, with association constants (Ka) of 4.0 X 10(9) M-1 (KY-BNP-I) and 2.0 X 10(10) M-1 (KY-BNP-II). With these mAbs, specific RIAs for BNP have been established. The least detectable quantities of BNP were 5 pg/tube (KY-BNP-I) and 1 pg/tube (KY-BNP-II). Cross-reactivities of alpha-human and rat atrial natriuretic polypeptides were less than 0.001%. These RIAs detected BNP-like immunoreactivity (BNP-LI) not only in the porcine brain but also in the canine brain, with the highest concentration in the medulla oblongata. These RIAs also detected BNP-LI in both the porcine and canine hearts and in the porcine plasma. The iv pretreatment of purified mAb[KY-BNP-II] almost completely blocked the hypotensive action of iv administered BNP in rats, with the concomitant suppression of BNP-induced increase of the plasma cyclic GMP level. These results indicate that our mAbs against BNP will serve as a useful tool for the elucidation of the physiological and pathophysiological significance of BNP as a neuropeptide and as a hormone.

Animals↗
PubMed1989

Detection and characterization of endothelin-1-like immunoreactivity in rat plasma.

Using two radioimmunoassays (RIAs) for endothelin-1 (ET-1) with and without a substantial cross-reactivity with ET-3, we have measured the plasma ET-1-like immunoreactivity (-LI) level in rat plasma. ET-1-LI was detected in plasma from male Wistar rats. ET-1-LI in rat plasma consisted of three components with molecular weights of 6K, 4K and 2.5K daltons by gel permeation chromatography. Two of the components were eluted at positions of big ET (4K) and synthetic ET-1 (2.5K). The remaining component was eluted at the preceding fraction (6K). No difference was observed in ET-1-LI of the small molecular form of ET (2.5K) between the two RIAs. Thus, there is little or no ET-3 in rat plasma, which has the sequence found originally in the rat genome. The concentration of the small molecular form of ET, presumably ET-1, in rat plasma was about 4 pg/ml.

Animals↗
PubMed1989

Isolation and sequence determination of rat cardiac natriuretic peptide.

We have isolated a cardiac natriuretic peptide of 5K daltons from the rat atrium and determined its amino acid sequence. The 5K cardiac natriuretic peptide was elucidated to be a 45-amino acid peptide with the sequence of S-Q-D-S-A-F-R-I-Q-E-R-L-R-N-S-K-M-A-H-S-S-S-C-F-G-Q-K-I-D-R-I-G-A-V-S-R- L-G-C-D - G-L-R-L-F by sequencing the native peptide and its lysyl endopeptidase digests. The sequence of this peptide was identical to the amino acid sequence [51-95] of the rat brain natriuretic peptide (BNP) precursor deduced from the cDNA sequence. The 5K cardiac natriuretic peptide, or BNP[51-95], was identified as the major storage and secretory form derived from the BNP precursor in the rat heart.

Amino Acid Sequence↗
PubMed1989

Occurrence of a novel cardiac natriuretic peptide in rats.

We established a specific radioimmunoassay for the ring structure of "iso-ANP" and detected iso-ANP[23-46]-like immunoreactivity (-LI) in the rat atrium (2.76 +/- 0.5 micrograms/g) and ventricle (13.9 +/- 5.7 ng/g). High performance-gel permeation chromatography revealed that iso-ANP[23-46]-LI in the rat heart was composed of two components with molecular weights of 10K and 5K. In reverse phase-high performance liquid chromatography, the retention times of these components were clearly different from that of synthetic iso-ANP. The 5K peptide was demonstrated to be present in the perfusate from isolated rat hearts and possessed binding ability to ANP receptors. This natriuretic peptide was, however, not detectable in other tissues including the brain. We conclude that the novel cardiac natriuretic peptide distinct from iso-ANP and ANP occurs in the rat heart and is secreted from the heart.

Amino Acid Sequence↗
PubMed1989

Endothelin in human plasma and culture medium of aortic endothelial cells--detection and characterization with radioimmunoassay using monoclonal antibody.

We have developed monoclonal (KY-ET-1-I) and polyclonal (ET-F5) antibodies against endothelin-1 (ET-1) and established sensitive radioimmunoassays (RIAs) with different specificities. The RIA with KY-ET-1-I detected ET-1, ET-2 and ET-3, while the RIA with ET-F5 recognized ET-3 very weakly. Using these RIAs, we have investigated the concentration and molecular forms of ET-1-like immunoreactivity (-LI) in culture medium of bovine aortic endothelial cells and human plasma. Culture medium of endothelial cells contained two major components compatible with big ET and ET-1. ET-1-LI was also detected in human plasma. ET-1-LI in human plasma consisted of apparent two components, the small molecular form emerging at the position of ET-1 and the large form with the peak eluting at the preceding fraction of the elution position of big ET. The concentration of the small form of ET in human plasma was about 5 pg/ml.

Animals↗
PubMed1989

Brain natriuretic peptide is a novel cardiac hormone.

Using a radioimmunoassay for brain natriuretic peptide (BNP), we have measured levels of BNP-like immunoreactivity (-LI) in extract of the porcine heart, in perfusate from the isolated porcine heart and in porcine plasma. BNP-LI was detected in the extract of the atrium, though no detectable amount of BNP-LI (more than 1 ng/g) was present in the ventricle. The BNP-LI level in the porcine atrium was 148.7 +/- 23.3 ng/g. BNP-LI was also detected in the perfusate from the heart. Basal secretory rate of BNP was 3.18 +/- 0.76 ng/min. Moreover, BNP-LI was detected in porcine plasma at the concentration of 4.2 +/- 1.3 pg/ml. Gel filtration studies showed that BNP is present in the atrium as a large molecule and is secreted into the circulation as a small molecule. The percentage of BNP-LI to atrial natriuretic peptide (ANP)-LI was almost the same among the extract, the perfusate and the plasma (2-3 percent). These results indicate that BNP is synthesized in and is secreted into the circulation from the heat in a similar fashion as ANP.

Animals↗
PubMed1989

Radioimmunoassay for brain natriuretic peptide (BNP) detection of BNP in canine brain.

We established a highly sensitive and specific radioimmunoassay (RIA) for BNP. Our RIA detected BNP-like immunoreactivity (-LI) in the porcine and canine brains but did not detect BNP-LI in the human, monkey or rat brain. The widespread distribution of BNP-LI was demonstrated both in the porcine and canine brains, with the highest concentration in the medulla oblongata. In contrast, the highest concentration of ANP-LI determined simultaneously was in the midbrain and the olfactory bulb. High performance-gel permeation chromatography coupled with RIA revealed that the major component of BNP-LI was eluted at the position of synthetic BNP with a small molecular weight (3K). These results indicate that the RIA for BNP serves as a useful tool to investigate physiological roles of BNP.

Animals↗
PubMed1989

Neuropathology of gracile axonal dystrophy (GAD) mouse. An animal model of central distal axonopathy in primary sensory neurons.

A new neurological mutant mouse shows a gracile axonal dystrophy (GAD). The degenerative lesion develops by postnatal day 80, first appearing in the most rostral portion of the gracile fascicles. This lesion then extends caudally to involve the entire gracile fascicles. Many axonal swellings (dystrophies) also appear in the degenerative lesions in proportion to their severity. The clinical findings develop in keeping with these pathological changes, and are characterized by tremor, ataxia and difficulty in moving the hind limbs. These start around day 80, and progress gradually to death about day 150. The lumbar dorsal roots, their spinal root ganglia and peripheral nerves are normal. Electron microscopic study shows dystrophic axons packed with neurofilaments, mitochondria and tubulovesicular structures. These may reflect some stagnation of axonal transport. The distribution of the lesions suggest that the GAD mouse has a central distal axonopathy involving primary sensory neurons of the lumbar dorsal root ganglia.

Animals↗
PubMed1989

Atrial natriuretic peptide in the ventricles of patients with dilated cardiomyopathy and human foetuses.

Immunohistochemical examination of atrial natriuretic peptide (ANP) was performed on endomyocardial biopsy specimens from 8 patients with dilated cardiomyopathy (DCM), 10 human foetal hearts obtained from legal abortions, and 8 adult hearts from autopsy control subjects without cardiovascular diseases. The indirect immunoperoxidase method, using specific monoclonal antibody to alpha-human ANP was employed. Immunoreactivity was observed at the light microscope level in the working ventricular cardiocytes of all patients with DCM as dark-brown, granular deposits. Peripheral plasma levels of ANP in these patients were also increased. In control adult hearts without cardiovascular diseases, immunoreactivity was detected both in the atria and in the ventricular impulse-conducting system, although the working ventricular cardiocytes were not immunoreactive. In foetal hearts, immunoreactivity was detected not only in the atria and ventricular impulse-conducting system, but also in the working ventricular cardiocytes. We conclude that ANP is present in the ventricular impulse-conducting system of the human hearts, and that ANP is also present in the working ventricular cardiocytes in patients with DCM as well as in human foetuses.

Antibodies, Monoclonal↗
PubMed1989

Neurotoxicity of human eosinophils towards peripheral nerves.

The toxicity of eosinophils towards peripheral nerves was examined using cultures of posterior ganglion cells from chick embryos. Eosinophils were also derived from a patient with significant "hyper-eosinophilia", peripheral neuropathy, bronchial asthma, myocardial damage and skin involvement. A sural nerve biopsy showed a severe to almost complete loss of myelinated fibers without pathological changes suggesting necrotizing vasculitis. Surviving neurons in a culture containing the patient's eosinophils or serum were markedly decreased in number as compared with those in normal subjects. These results support the possibility that the peripheral neuropathy in the patient caused by toxic agents derived from eosinophils.

Adult↗