Hamao Ijichi

Estimation of right ventricular volume with two dimensional echocardiography.

Abstract To evaluate the applicability of two dimensional echocardiography to right ventricular volume determination, a study was made of 33 consecutive patients separated into three groups (control, right ventricular volume overload and right ventricular pressure overload). Biplane two dimensional echocardiograms that were perpendicular to each other were obtained from the apical approach. The echocardiographic right ventricular volume, calculated by applying Simpsons rule, was considered to be right ventricular body volume without right ventricular outflow tract volume. The echocardiographic dimensions of the right ventricular long, short and maximal short axes were also measured in each view. These volumes and dimensions were compared with both the angiographic right ventricular body volumes calculated by applying Simpsons rule and with the values in each group. Correlation between the echocardiographic and the angiographic right ventricular body volumes (r = 0.94 at end-diastole, r = 0.84 at end-systole) was good and much better than that between echocardiographic right ventricular dimensions and angiographic right ventricular body volumes. Echocardiographic calculation of right ventricular body volume was useful in distinguishing the control group from the group with right ventricular volume overload (p The correlation between the echocardiographic dimensions of the right ventricular long axis and angiographic right ventricular volumes was poor, whereas that between the echocardiographic dimensions of the right ventricular short or maximal short axis and the angiographic right ventricular volumes was fairly good. It was therefore suspected that during right ventricular enlargement, the increase in size is more extensive in the direction of the short than in the direction of the long axis. It is concluded that estimation of right ventricular volume and morphology with two dimensional echocardiography may be of value in clinical practice.

Studies on the neutralizing mechanism of antithrombin activity of heparin by protamine

Abstract Protamine has been used as the principal neutralizing agent of heparin. The neutralizing mechanism was analyzed by means of two dimensional crossed immunoelectrophoresis and Heparin Sepharose affinity chromatography. Electrophoretic mobility of AT III of heparinized plasma was increased depending on the heparin concentrations, however it was returned to the original, when heparinized plasma was neutralized with protamine. Meanwhile protamine treatment did not affect on the electrophoretic mobility of AT III itself. AT III dissociated from Heparin Sepharose by protamine had progressive antithrombin activity and developed an immediate antithrombin activity in the presence of heparin. These results indicate that protamine dissociates AT III-heparin complex by means of binding to heparin and that the dissociated AT III recovers an original antithrombin activity.

IgE-mediated 14C-serotonin release from rat mast cells modulated by morphine and endorphins.

The formaldehyde method was used to examine the interaction of PGE1 with morphine, beta-endorphin and Met-enkephalin on rat mast cells by their effects on IgE-mediated 14C-serotonin release. PGE1 (2x10(-8) -2x10(-5) M) caused a dose-related inhibition of the mediator release 1 min after an antigen challenge, and morphine (3x10(-7) -3x10(-5) M) reversed this PGE1 effect dose-dependently and stereospecifically; naloxone (2x10(-4) M) antagonized this action of morphine. Beta-Endorphin (3x10(-7) -10(-5) M) and Met-enkephalin (3x10(-6) -10(-4) M) mimicked this morphine action dose-dependently and were antagonized by naloxone (2x10(-4) M). These results suggest that morphine and endorphins modulate immunological mediator release from rat mast cells through opioid receptors.

Central attenuation of aortic baroreceptor reflex in prehypertensive DOCA-salt-loaded rats.

To determine whether the arterial baroreceptor reflex can act to oppose the development of hypertension, deoxycorticosterone acetate (DOCA)-salt hypertension was produced in sinoaortlcdenervated and sham-operated rats. Systolic blood pressure measured by tail cuff started to increase in both sinoaortic-denervated and sham-operated rats 7 days after DOCA treatment, and the hypertension developed identically in both denervated and sham-operated rats. These findings suggest that the baroreceptor reflex cannot act against the development of hypertension. To determine whether the baroreceptor reflex is attenuated before the development of hypertension, bradycardic and sympathoinhibitory responses to i.v. injections of norepinephrine were examined. Bradycardic and sympathoinhibitory responses were significantly smaller in DOCA-salt-treated rats in both prehypertensive (5th day after DOCA-salt treatment) and hypertensive stages (21st day after treatment). In urethane-anesthetized DOCA-loaded and control rats on the 5th day after treatment, aortic depressor nerve stimulation elicited frequency-dependent depressor and bradycardic responses accompanied by inhibition of sympathetic nerve activity in both DOCA-loaded and control rats. However, those responses were significantly smaller in DOCA-loaded rats than in control rats. These results suggest that the central component of the baroreceptor reflex mediated by the aortic depressor nerve is impaired before hypertension develops and that this impairment may contribute to the development of hypertension in DOCA-salt-treated rats.

Pressor Responses to Intracisternal Injection of Hypertonic NaCl in Rats

Hypertonic NaCl solution injected into the cisterna magna of anesthetized rats produced dose-dependent pressor responses accompanied by slight tachycardia. Similar injections of hypertonic urea solution were ineffective. Because the early phase of the pressor response to hypertonic NaCl was always accompanied by increased sympathetic nerve firing and was inhibited following α-adrenergic blockade with phentolamine, initial pressor response was attributed to sympathetic hyperactivity. On the other hand, because the later phase of the pressor response was unaffected either by adrenalectomy or by α-adrenergic blockade, but was significantly inhibited by hypophysectomy or by pretreatment with a vasopressin antagonist, the later pressor response was ascribed to an increased release of endogenous vasopressin. Thus, our findings indicate that central pressor responses to hypertonic NaCl solution involve two different mechanisms: sympathetic hyperactivity in the early phase and vasopressin release during the later phase. In spontaneously hypertensive rats (SHR), both pressor and sympathetic responses to intracisternally injected NaCl were greater than in Wistar-Kyoto rats (WKY). Our results further indicate hypersensitivity to NaCl around the brain stem in SHR, which could account for the increased sympathetic activity and cause SHR to develop hypertension.

Effect of inhibition of Na+-K+ ATPase on the prostacyclin generation of cultured human vascular endothelial cells.

Prostacyclin (PGI2) generation of cultured human vascular endothelial cells (VEC) was observed coincidentally with the increase of 45Ca net influx. Ca ionophore A23187 enhanced not only PGI2 generation and 45Ca net influx but also 45Ca efflux. PGI2 generation was completely abolished by the pretreatment with Ca++ immobilizer, TMB-8. A Na+-K+ ATPase inhibitor, ouabain increased 45Ca net influx, but decreased 45Ca efflux, and enhanced PGI2 generation. These observation indicate that PGI2 generation of VEC may be regulated by not only Ca++ but also Na+, and it was suggested that enhanced PGI2 generation by ouabain might be derived from the increased cytosolic Ca++concentration by the decreased Ca++ efflux, and it was considered to be originated from the suppression of Na+-Ca++ exchange systems by the increased intracellular Na+ concentration via inhibition of Na+-K+ ATPase activity by ouabain. Enhancement of PGI2 generation of VEC by the increased ouabain like substances (OLS) in hypertension is suspected to be beneficial on the maintenance of vascular homeostasis.

Effect of Decreased Dopamine Synthesis on the Development of Hypertension Induced by Salt Loading in Spontaneously Hypertensive Rats

To clarify role of dopamine in the development of hypertension, the effect of a dopamine synthesis inhibitor on blood pressure and urinary output of catecholamines was investigated in spontaneously hypertensive rats (SHR) fed with high sodium diet. Rats were orally given carbidopa, an inhibitor of peripheral DOPA decarboxylase, or the vehicle for 4 weeks. Carbidopa administration accelerated significantly the development of hypertension as compared to the control SHRs with the vehicle. Carbidopa administration resulted in a significant decrease of urinary excreted sodium, urinary dopamine and renal content of dopamine. Conversely, carbidopa administration resulted in a significant increase of urinary excreted norepinephrine, urinary epinephrine and renal content of norepinephrine as compared with control SHRs. These results suggest that decreased dopamine synthesis in kidneys and probably other peripheral tissue accelerates the development of hypertension, mediated by a decrease of natriuresis and an enhancement of sympatho-adrenomedullary activity. Dopamine plays an important role in its protective action against the development of hypertension enhanced by salt loading, and decreased dopaminergic mechanisms accelerated hypertension in SHR.

Demonstration of antibody for glutamic pyruvic transaminase (GPT) in chronic hepatic disorders.

The present paper describes the detection of an autoantibody for glutamic pyruvic transaminase (GPT) in sera of patients with chronic hepatic disorders. In 16 out of 500 patients, the existence of an antibody for pig GPT was demonstrated by the double antibody method, gel filtration and radioimmunoelectrophoresis. The antibody was demonstrated as an immunoglobulin G (IgG) with either polyclonal or monoclonal type (kappa or lambda). The binding portion of IgG with GPT was determined as the fragment Fab, but not Fc of IgG. Because the binding of 125I-pig GPT with the patients antibody was displaced by human GPT, this antibody may have the characteristic of cross reacting with both pig and human GPT. Although the mechanism of production of the antibody for GPT and the pathological significance of the antibody in chronic hepatic disorders remained obscure, possible inhibition of GPT activity in serum is suggested in the presence of this antibody.

Inversion of chromosome 3 in a case of chronic myelogenous leukemia with abnormal thrombopoiesis

A patient with chronic myelogenous leukemia (CML) associated with a remarkable increase of micromegakaryocytes in bone marrow was revealed to have an abnormality of a long arm of chromosome #3, i.e., inv(3)(q21q26), in addition to a complex Ph translocation: t(9;22;15)(q34;q11;q22). Although several cases of acute leukemia with inv(3)(q21q26) and abnormal megakaryocytes have been reported, this is the first case in which the association of inv(3)(q21q26) with a megakaryocytic abnormality was observed in a patient with CML. Our findings suggest that this structural rearrangement may be more specifically associated with abnormal thrombopoiesis than are other structural anomalies of 3q.

Inhibitory roles of the hypothalamic atrial natriuretic polypeptide on the vasopressin release in the sodium-loaded rats.

Implication of the brain atrial natriuretic polypeptide on the vasopressin release was investigated using rats fed with a high-sodium containing diet. Sodium loading increased not only the blood pressure but also the urinary output of vasopressin significantly. The plasma vasopressin concentration increased about 10 times after the intracerebroventricular injections of angiotensin II. Thereby, magnitude of the response was significantly smaller in the rat fed with a high sodium diet than in rats with the regular-diet. The hypothalamic content of both vasopressin and atrial natriuretic polypeptide was significantly larger in the high-salt group than the regular-salt. The intraventricular injections of atrial natriuretic polypeptide abolished the vasopressin release induced by the intraventricular injections of angiotensin II. These results indicate that the vasopressin production in the hypothalamus is increased, but the release is relatively suppressed in the sodium-loaded rats, and that increased hypothalamic atrial natriuretic polypeptide is involved in the suppression of the vasopressin release and in decreasing their sodium appetite to avoid the high sodium environment.