Fumihiko Kurimoto

Atrial natriuretic factor inhibits vasopressin secretion from rat posterior pituitary

The effects of synthetic atrial natriuretic factor (ANF) were studied in superfused rat posterior pituitary gland. ANF (10(-6)M, 10(-10)M) significantly inhibited basal as well as KC1 (50 mM) or angiotensin II-stimulated immunoreactive arginine vasopressin secretion. The magnitude of inhibition was greater at 10(-6)M than at 10(-10)M. ANF also decreased cAMP secretion and increased cGMP secretion from the posterior pituitary. These results suggest that ANF directly acts on the posterior pituitary to inhibit arginine vasopressin secretion and that this effect is, at least, partly mediated by the changes in cyclic nucleotide production.

Gelatin-specific humoral and cellular immune responses in children with immediate- and nonimmediate-type reactions to live measles, mumps, rubella, and varicella vaccines ☆ ☆☆ ★

BACKGROUND This study was designed to investigate the development of both cellular and humoral immune responses to gelatin in patients with vaccine-related immediate and nonimmediate reactions. Our purpose was to define the nature of the responses in the different clinical states. METHODS Six patients with immediate reactions and 21 patients with nonimmediate reactions after inoculation of various live vaccines were studied. Measurement of gelatin-specific IgE was performed in all subjects. Gelatin-specific T-cell responses detected by an in vitro lymphocyte proliferation assay and by an assay for IL-2 responsiveness were investigated to compare the immune response in patients with the two types of reaction. RESULTS All six patients with immediate reactions had IgE responses to gelatin, whereas none of the 21 patients with nonimmediate reactions had any anti-gelatin IgE. All of the six patients with immediate reactions and 17 of the 21 patients with nonimmediate reactions exhibited positive T-lymphocyte responses specific to gelatin. CONCLUSIONS Immediate and nonimmediate reactions are caused by different types of allergy to gelatin, and cell-mediated immunity to gelatin may play an important role in the pathogenesis of nonimmediate reactions.

Plasma immunoreactive endothelin, but not thrombomodulin, is increased in patients with essential hypertension and ischemic heart disease.

To ascertain an involvement of vascular endothelial cells in cardiovascular disease, we have determined plasma levels of two endothelium-derived substances, endothelin (ET) and thrombomodulin (TM), in essential hypertension (EH) and ischemic heart disease. Plasma ET was determined by radioimmunoassay (RIA) after extraction. Plasma TM levels were determined by enzymunoimmunoassay. Plasma ET levels were significantly elevated in patients with EH involving target organ damage, vasospastic angina pectoris (VSA), and acute myocardial infarction (AMI), especially in those associated with cardiogenic shock. There was a weak but significant correlation between plasma ET levels and serum creatinine concentration in patients with EH. Plasma ET levels were elevated even before the coronary spasm in patients with VSA, whereas they did not show any further increase during the spasm. In contrast, plasma TM levels in patients with EH and VSA did not show a significant difference from that in normal subjects. These results suggest that ET plays an important role in the pathophysiology of EH and ischemic heart disease, and also that increases in plasma ET cannot be simply attributed to a leakage of the peptide from the injured endothelial cells.

逆相C18シリカカラムを用いた高感度Radioimmunoassayによる血漿8-arginine vasopressinの測定法

A highly sensitive and simple radioimmunoassay for the measurement of 8-arginine vasopressin (AVP) in human plasma has been developed. The dose response curve ranges from 0.025 to 8 pg/tube. This simple extraction technique employing an ODS C18 column recovered 87.1 +/- 10.4 (mean +/- SD)% of AVP in the range of 1-10 pg/ml added to 0.5 ml plasma. Determination of AVP in each fraction of plasma, which was gel-filtrated through a Sephadex G25 (1 X 25 cm), revealed that the fraction of plasma AVP was superimposed on that of authentic AVP, and interference of non-specific substances was completely eliminated by an ODS C18 column. Using the assay, 13 of 16 patients with diabetes insipidus (DI) showed plasma AVP concentrations ranging from 0.03 to 0.21 pg/ml, and the other 3 patients had less than 0.03 pg/ml. The AVP concentrations of DI were clearly distinguished from those obtained in normal subjects (0.30-4.20 pg/ml, n = 65). The within and between assay variability was about 10% each. Plasma AVP concentrations (mean +/- SD) of normal subjects (n = 6) standing, sitting, and supine after an overnight of fluid deprivation were 2.41 +/- 1.15, 1.95 +/- 0.85 and 0.97 +/- 0.48 pg/ml (30 min after) respectively. Plasma AVP concentrations of normal subjects (n = 6) after water load (20 ml/kg wt) were clearly reduced from 1.89 +/- 1.00 (before) to 0.42 +/- 0.21 (standing for 60 min) and also from 0.89 +/- 0.41 to 0.40 +/- 0.22 pg/ml (supine for 60 min).

Sulfidoleukotriene Release Test (CAST) in Hypersensitivity to Nonsteroidal Anti-Inflammatory Drugs

There is a great need to develop a method for making an accurate and reliable in vitro diagnosis of adverse hypersensitivity reactions to drugs. We measured the amount of sulfidoleukotriene (sLT) released from the peripheral blood leukocytes obtained from 25 patients who developed hypersensitivity reactions following the administration of nonsteroidal anti-inflammatory drugs (NSAIDs); 12 patients demonstrated reactions to Voltaren, 8 patients to Bufferin, and 5 patients to Sedes G. The stimulation index, the ratio of the amounts of sLT (pg/ml) incubated with and without drugs, was considerably higher in the patients than in the controls, which consisted of 5 nonallergic healthy subjects. The sensitivity of the CAST (cellular antigen stimulation test) was evaluated to range from 62.5 to 80%, while the specificity was 70-100%. The CAST may thus be useful as a novel in vitro test system in order to screen for possible hypersensitive reactions to NSAIDs with both reliability and safety.

Increased levels of blood platelet‐activating factor in bronchial asthmatic patients with active symptoms

Levels of platelet‐activating factor (PAF) in blood from 12 bronchial asthmatic patients (six atopic and six nonatopic) were measured by radioimmunoassay after lipid extraction and separation by high‐performance liquid chromatography. None of the patients were given disodium cromoglycate and prednisolone, and they were instructed to take only regular medications during the tests. Blood was drawn from the patients in a fasting state, and PAF levels were compared between the times when they were free of asthmatic symptoms and when they had mild spontaneous attacks. Ten (six atopic and four nonatopic) out of 12 patients, when they had the asthmatic attacks, showed higher levels of PAF than when they were free of the symptoms. Blood PAF levels of the patients with the active symptoms were significantly higher than those of normal healthy control subjects, suggesting that PAF may play a role in bronchial asthma.

Leptin in women with eating disorders.

The aim of the present study was to determine the factors controlling leptin secretion and to clarify the role of leptin in eating disorders. The subjects were 152 eating-disordered women with different fat mass, eating behavior, and endocrine abnormalities and 24 age-matched control subjects. The body fat mass, eating behavior score, and plasma leptin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), triiodothyronine (T3), free thyroxine (T4), insulin, and cortisol levels were evaluated for each subject. In patients with eating disorder, logarithmic values for leptin were significantly correlated with the body fat mass (r = .828, P < .001), eating behavior score (r = .777, P < .001), and LH (r = .465, P < .001), FSH (r = .440, P < .001), T3 (r = .572, P < .001), insulin (r = .410, P < .001), and cortisol (r = -.389, P < .001) levels. After adjusting for fat mass, the partial correlations of log leptin with LH, FSH, insulin, and cortisol were not statistically significant, but log leptin remained correlated with T3 (r = .390, P < .01). Stepwise regression analysis showed that the body fat mass and eating behavior score were significant determinants of leptin levels. These results suggest that eating behavior, as well as the body fat mass, is the control factor for leptin secretion in eating disorders.

Radioimmunoassay for endothelin and immunoreactive endothelin in culture medium of bovine endothelial cells

Using a synthetic 21-residue endothelin as antigen, we have produced an antiserum for endothelin and developed a specific and sensitive radioimmunoassay (RIA) for endothelin. The minimum detection limit of the RIA was 1 pg/tube. Immunoreactive (ir-) endothelin was extracted from the culture medium by Bondelute C8 column. The ir-endothelin in the culture medium of endothelial cells (EC) from bovine pulmonary artery and carotid artery was 1.48 ng/ml and 3.31 ng/ml, respectively. Reverse-phase high performance liquid chromatography coupled with the RIA revealed that ir-endothelin in the culture medium comprised one major component corresponding to synthetic endothelin. In addition, the cultured EC of bovine pulmonary artery were specifically stained by immunohistochemical technique. These results suggest that endothelin could be produced in the EC of the pulmonary and carotid arteries besides the aorta. The RIA presented in this study could be an useful tool to investigate the pathophysiologic significance of endothelin.

Galanin as a Physiological Neurotransmitter in Hemodynamic Control of Arginine Vasopressin Release in Rats

Previous neuroanatomical studies have revealed a localization of galanin in several nuclei in the brain stem which are involved in the hemodynamic control of arginine vasopressin (AVP) release. The present study, therefore, investigates the contribution of endogenous galanin to the plasma volume-mediated control of AVP release in conscious rats. Injection of synthetic rat galanin (12.5-50 pmol/rat) into the cisterna magna (i.c.s.) suppressed plasma AVP increased by polyethylene glycol-induced hypovolemia (2.45 +/- 0.24 pg/ml at 50 pmol/rat vs. the vehicle group 5.72 +/- 0.69 pg/ml, p < 0.01). In contrast, when plasma AVP was suppressed by isotonic plasma volume expansion, immunoneutralization of endogenous galanin by antigalanin-antibody i.c.s. significantly reversed the suppression (1.02 +/- 0.07 pg/ml vs. vehicle group 0.63 +/- 0.05 pg/ml, p < 0.01) without altering the mean arterial blood pressure. These results suggest that endogenous galanin is physiologically involved in the plasma volume-mediated control of AVP release through an inhibitory action on this pathway.

Response to cyclosporin and low-dose methylprednisolone in aggressive systemic mastocytosis.

BACKGROUND There is no effective treatment for aggressive systemic mastocytosis. OBJECTIVE The purpose of this study was to investigate the effect of cyclosporin and low-dose methylprednisolone in a 64-year-old man with aggressive systemic mastocytosis. METHODS Immunohistochemical studies were done on biopsy specimens from the skin and other organs. Mast cells, predominantly containing tryptase, were derived from human umbilical cord blood cells cultured in the presence of stem-cell factor and IL-6. IgE-sensitized cultured human mast cells were activated by anti-IgE, and the effect of cyclosporin on histamine release was investigated. In addition, blood and urine levels of various mediators were measured in the patient before and after therapy. RESULTS Biopsy specimens of the patients skin lesions showed an increase of mast cells; cells containing tryptase (but not chymase) comprised 20% to 50% of the skin mast cells. Histamine release from activated cultured mast cells was inhibited by cyclosporin in a concentration-dependent manner. When the patient was treated with cyclosporin and low-dose methylprednisolone, he showed a good response. CONCLUSION Cyclosporin combined with low-dose methylprednisolone may be a reasonable therapy for aggressive systemic mastocytosis.