Pharmacological properties of quisqualate- and kainate-preferring glutamate receptors induced in Xenopus oocytes by rat and chick brain mRNA

Quisqualate- and kainate-preferring glutamate receptors were studied in Xenopus oocytes injected with rat and chick brain mRNA. All ligands effective at ionotropic quisqualate sites, agonists as well as antagonists, were found to inhibit kainate responses. Ionotropic quisqualate and kainate responses were distinguished by gamma-L-glutamylglycine but not by its D-isomer. No difference was detected between responses induced by rat brain mRNA and chick brain mRNA, suggesting that the properties of non-N-methyl-D-aspartate-type glutamate receptors of rat and chick brains are essentially the same.

Characteristics of pressor response to endothelin in spontaneously hypertensive and Wistar-Kyoto rats

Endothelin, an endothelium-derived vasoconstrictor peptide, and angiotensin II were intravenously injected into the femoral vein of normotensive Wistar-Kyoto (WKY) rats that had been anesthetized with urethane. Blood pressure and heart rate were recorded from a cannula inserted into the carotid artery. All experiments were carried out after treatment with adrenergic and cholinergic antagonists. Endothelin showed a potent, dose-dependent pressor action. The dose-response relations for the increase in blood pressure of rats receiving endothelin were comparable with those of rats receiving angiotensin II. However, endothelin showed far more long-lasting effects. Endothelin-induced responses consisted of three phases: a rapid and transient depressor phase and then two phases of pressor (transient and long-lasting) response. Nicardipine (0.1 mg/kg), a dihydropyridine Ca2+ channel blocker, markedly attenuated the slow phase of the pressor response but only slightly attenuated the rapid one. The pressor action of endothelin was not inhibited by continuous infusions of saralasin, which almost abolished the angiotensin II-induced pressor response. Endothelin-induced pressor response was also not attenuated by indomethacin, a prostaglandin synthesis inhibitor. These data provide evidence that endothelin produces a unique, potent, and long-lasting pressor response, which appears to be in part related to the activation of Ca2+ channels. In 12-week-old spontaneously hypertensive rats (SHR), the maximal pressor response to endothelin was slightly but significantly greater than that in age-matched WKY rats, but the dose dependency of the response was approximately consistent with that in WKY rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Isoproterenol stress thallium scintigraphy for detecting coronary artery disease

The value of exercise thallium scintigraphy in detecting coronary artery disease is well established. However, there are at times situations in which the exercise test cannot be readily used. Isoproterenol (ISP) stress ECG (ISP-ECG) is reportedly a useful method in diagnosing coronary artery disease. In the present study, we assessed the diagnostic value of ISP thallium scintigraphy, comparing it with those of ISP-ECG and exercise thallium scintigraphy. The study population consisted of 24 patients who had histories of chest pain without previous myocardial infarction. ISP was given at increasing doses of 0.02, 0.04, 0.08 micrograms/kg/min at 3-minute intervals, and was terminated for any of the following reasons: angina, significant arrhythmia, significant ST segment depression (greater than or equal to 0.1 mV) or target heart rate. Thallium scintigrams were obtained immediately after terminating ISP infusion, and after a 3-hour delay, redistribution scans were obtained. Scintigrams were considered positive when a reversible defect was present. In nine patients who underwent exercise tests, exercise thallium scintigraphy was also performed. After the stress tests, coronary angiography was performed. According to the presence or absence of significant coronary artery stenosis (greater than or equal to 75%), all subjects were divided into two groups: coronary artery disease (CAD) group (n = 12) and so-called normal coronary (NC) group (n = 12). 1. Among 12 patients in the CAD group, ISP induced anginal pain in six (50%), and ISP-ECG and ISP thallium scintigraphy were positive in 10 (83%) and in 11 (92%), compared with four (33%), four (33%) and two (17%) in the NC group.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of invasive thymoma in the left hilus of the lung]

Reported is the case of a 62-year-old man who was admitted to our hospital because of the presence of a left hilar mass found during a routine chest X-ray examination. Shortly thereafter, a left thoracotomy was performed. The tumor was located under the aortic arch in the left hilus of the lung and had invaded the pericardium and pulmonary trunk. There was no connection, however, to the anterior mediastinum. A histological examination revealed an invasive thymoma of epithelial cell of the predominant type. Seen scattered abroad were thymic tissue in the adipose tissue around the tumor of the left hilus. Postoperatively, a distant metastasis of the right lung was observed and the patient died due to respiratory failure.

Glutamate receptor subtypes may be classified into two major categories: a study on Xenopus oocytes injected with rat brain mRNA

Three major subtypes of glutamate receptors that are coupled to cation channels are known. Recently an additional subtype that is coupled to G proteins and stimulates inositol phospholipid metabolism (the metabotropic glutamate receptor) has been proposed. The pharmacological characteristics of this receptor have now been examined. Although it shares some agonists with N-methyl-D-aspartate- and quisqualate-subtype receptors, it shares virtually no antagonists with any of the three cation channel-coupled receptor subtypes. Thus the metabotropic glutamate receptor belongs to a receptor category that is completely different from that of the other three receptor subtypes, not only functionally, but also pharmacologically.

[Histological studies of the mouse palate. Formation of the incisive suture]

The morphology of the incisive suture (InS) in mice was studied using specimens stained with alizarin red S. Formation of this suture was also studied histologically with light microscopy. The InS is composed of three regions; the 1st and 2nd are short and well interdigitated regions respectively situated on the inside and the outside of the anterior palatine foramen. The 3rd region is a loose curved region situated on the outside and the nasal cavity side of the cranium. The InS surrounds the posterior region of the incisors in the upper jaw with a ring-like form. The InS is formed in four steps; cell aggregation (19 days postconception and one day postpartum), formation of bone extensions and collagen fiber bundles (4 and 7 days postpartum), modification of the orientation of these fiber bundles (14 days postpartum), and formation of the serrated suture and fiber bundles with regular orientation (21, 30 and 60 days postpartum). Furthermore, the distance between the bones in the InS was found to be from 40 to 60 microns. The morphology of the InS indicates that it functions as a strong connection between bones, and as a buffer zone. These functions of the InS seem to correspond closely with the function of the incisors in the upper jaw.

Oligonucleotide-genotyping as a method of detecting the HLA-DR2 (DRw15)-Dw2, -DR2 (DRw15)-Dw12, -DR4-Dw15, and -DR4-D"KT2" haplotypes in the Japanese population

We synthesized pairs of four different oligonucleotides, F22, F29, F42, and F158, to analyse the HLA-DR2 (DRw15) and -DR4 haplotypes in the Japanese population. After enzymatically amplifying the HLA-DRB1 gene, we hybridized the oligonucleotide probes with DNA extracted from 42 donors. Hybridization was completed between F22 and the DNA of haplotype DR2 (DRw15)-Dw2, between F29 and the DNA of DR2 (DRw15)-Dw12, between F42 and the DNA of DR4-D"KT2", and between F158 and the DNA of DR4-Dw15. In keeping with the nucleotide sequences of the probes, F29 hybridized also with DNA from the DR9-Dw23 haplotype and F158 with that from some of the DRw8 haplotypes (DRw8-Dw8.3) in the Japanese population. Results of this study demonstrate that the four oligonucleotides make useful probes for detecting the haplotypes above.

[The heart rate alternative sequence during pharmacologic total autonomic blockade in patients with sick sinus syndrome: differential effects in relation to age]

To study the age-related changes of the sinus node function and the variations of influence of autonomic nervous system, pharmacologic total autonomic blockade (TAB) was conducted in 35 patients with symptomatic sinus bradycardia (21 men and 14 women, 50 +/- 21 years, mean +/- SD). Twenty-one patients [Group I, consisting of 14 patients younger than 60 years (group IY) nd 7 patients 60 years or older (group IE)] had a normal intrinsic heart rate (IHRo), and 14 patients had an abnormal IHRo [Group II, consisting of 8 patients younger than 60 years (group IIY) and 5 patients 60 years or older (group IIE)]. The basic cycle length was significantly longer in group II than in group I, suggesting that intrinsic sinus node function was more seriously deteriorated in group II in spite of the compensatory effect of autonomic regulation. In group II it was characteristic that the cycle length (CL) after atropine sulfate administration was longer than the CL of the predicted intrinsic heart rate (IHRp). Otherwise, some group II patients might be regarded as normal by atropine sulfate administration alone. Parasympathetic tone showed a negative correlation with age, and it was most enhanced in group IIY, suggesting that parasympathetic negative chronotropy was stronger in this group. In the course of propranolol administration, prolongation of CL was significantly larger in group IIE than in group IIY, but there was no age-related difference in group I. In group II, beta-adrenergic blockade with propranolol administration showed that sympathetic positive chronotropy was a critical compensatory factor around the upper limit of the CL of IHRp.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of FK-506, a novel immunosuppressive drug on murine systemic lupus erythematosus

A novel immunosuppressive compound extracted from the fermentation broth of Streptomyces tsukubaensis belongs to the macrolide family. We gave this drug (FK-506) to MRL/lpr and NZB X NZW F1 (B/W F1) mice, an animal model of human systemic lupus erythematosus (SLE), to investigate its effect on the course of the disease. This drug showed potential to prolong the lifespan, to reduce proteinuria, and to prevent the progression of nephropathy. Appreciable differences in the levels of anti-dsDNA antibodies between treated and control animals were nil.

The significance of abnormal systolic blood pressure response during supine ergometer exercise and postexercise in ischemic heart disease, studied by exercise radionuclide ventriculography

The prognostic value of abnormal postexercise systolic blood pressure (BP) response has not been investigated. Therefore, the significance of abnormal BP response during exercise and postexercise was examined in 169 patients with ischemic heart disease subjected to supine ergometer exercise gated equilibrium radionuclide ventriculography, coronary arteriography, and follow up averaging 3.6 years. Abnormal BP response during exercise (exertional "hypotension") was defined as 1) a failure of BP to rise by at least 11 mmHg or 2) an initial rise in BP but subsequent fall by more than 10 mmHg during exercise. Abnormal BP response during postexercise (postexercise "hypertension") was defined as an increase of more than 10 mmHg above the peak exercise BP. Of 169 patients, 51 (30%) had an abnormal BP response. Four types of BP response were identified: exertional "hypotension" (group 1a, n = 11), postexercise "hypertension" (group 1b, n = 30), exertional "hypotension" with postexercise "hypertension" (group 1c, n = 10) and normal BP response (group 2, n = 118). Both average exercise duration and peak heart rate were significantly lower in groups 1a, 1b and 1c than in group 2. The severity of exercise ST-segment depression was greater in groups 1b and 1c than in group 2. However, there was no significant difference in the severity of exercise ST-segment depression between group 1a and group 2. A decline in ejection fraction occurred more frequently in groups 1b and 1c than in group 2. Patients in groups 1a, 1b and 1c had more extensive coronary artery disease (CAD) than did patients in group 2. Medically treated patients with an abnormal BP response (groups 1a, 1b and 1c) had a poorer prognosis than did those with a normal BP response (group 2). These findings suggest that an abnormal BP response during supine exercise is infrequent, but is usually associated with impaired exercise tolerance and severe CAD. An abnormal postexercise BP response is also infrequent, but is more closely associated with evidence of myocardial ischemia and global left ventricular dysfunction than exertional "hypotension". In conclusion, postexercise "hypertension" has the same value as exertional "hypotension" as a predictor of poor prognosis.

Evaluation of myocardial perfusion abnormality by profile analysis for digital subtraction angiogram

For quantitative estimation of ischemia, ECG-synchronized digital subtraction angiography was performed for selective coronary arteriography. The authors obtained sequential myocardial perfusion images at the arterial, capillary, and venous phases. Profile densitometry was performed along the cross section perpendicular to the long axis of the left ventricle to assess regional myocardial perfusion at the capillary phase quantitatively. By this densitometry, the volumes of vascular bed perfused by the left coronary artery could be estimated, and further, nontransmural myocardial infarction could be differentiated from transmural myocardial infarction through the profile of its density curve. This method appears to be useful for the analysis of myocardial perfusion of ischemic heart disease.

Effect of nifedipine on left ventricular function during exercise in patients with stable effort angina. Relation of its efficacy to the severity of coronary artery disease

To evaluate whether the effect of nifedipine on left ventricular function relates to the severity of coronary artery disease (CAD) or not, supine graded ergometer exercise testing was performed before and after sublingual administration of 10 mg nifedipine in 24 patients with stable effort angina. To minimize the effect of nifedipine on myocardial oxygen consumption, exercise before and after nifedipine was discontinued at the same target rate pressure product. Percent (%) left ventricular ejection fraction (EF) [EF during exercise/EF at rest.100] was measured before and after nifedipine by radionuclide angiocardiography. The angiographic degree of CAD was defined by Gensini's CAD scoring as follows: severe CAD: greater than or equal to 50, moderate: less than 50 greater than 20 and mild: less than or equal to 20. After nifedipine, left ventricular function (%EF) was improved in all 6 patients with mild CAD, but was worsened in all 9 patients with severe CAD. Maximal ST segment depression during exercise was improved in 5 of 6 patients with mild CAD, while improvement was induced in 5 of 9 patients with moderate CAD and in 3 of 9 patients with severe CAD. Jeopardy of coronary collateral vessels may have an influence on the effect of nifedipine. It is suggested that the effect of nifedipine on left ventricular function is influenced by the severity of CAD when most of its effect on myocardial oxygen consumption is eliminated.

Characterization of glutamate receptors induced in Xenopus oocytes after injection of rat brain mRNA

Xenopus oocytes in which poly(A)+ mRNA isolated from rat brains were previously injected, exhibited at least 3 categories of current responses to excitatory amino acids. They were oscillatory responses to glutamate (Glu) or quisqualate (QA), smooth large responses to kainate (KA), and smooth small responses to Glu and QA. Oscillatory responses were mediated by a metabotropic type of Glu receptor which is coupled to a G-protein but not directly to an ionic channel. Amplitudes of smooth Glu responses and smooth QA responses were similar in size, and were not additive to each other, suggesting a common receptor mediating both responses. L-Glutamylglycine inhibited KA responses in a competitive manner without affecting smooth Glu/QA responses, indicating that KA and smooth Glu/QA responses were mediated by separate receptors. From these results, it was concluded that the injection of rat brain mRNA induced at least 3 different glutamatergic receptors: receptors mediating (a) KA responses and (b) smooth Glu/QA responses, and (c) the metabotropic Glu receptor. The former two may most likely correspond to Glu receptor subtypes preferring KA and QA, respectively, as seen in the brain.

Pertussis toxin suppresses long-term potentiation of hippocampal mossy fiber synapses

The long-term potentiation (LTP) was studied using rat hippocampal slices in vitro. LTP in mossy fiber-CA3 pyramidal cell synapses was markedly suppressed in slices prepared from rats which had previously received intraventricular injection of pertussis toxin (PTX), compared with the bovine serum albumin-injected controls, suggesting the involvement of G-proteins in the mechanism of LTP in mossy fiber synapses. In contrast, LTP in Schaffer/commissural-CA1 pyramidal synapses was not affected by PTX pretreatment.

Tricuspid regurgitation diagnosed by intravenous digital subtraction angiography

In spite of numerous available diagnostic methods, controversies concerning the precise diagnosis of tricuspid regurgitation (TR) still remain. In right ventriculography, catheter placement may modify tricuspid valvular function. Though noninvasive Doppler echocardiography is a useful method, it is sometimes too sensitive for clinical use. Furthermore, it is not applicable to cases in which ultrasound penetration is limited. In this study, we evaluated TR using intravenous digital subtraction angiography (DSA), which can provide good images even in cases with poorly recorded echocardiograms. For this study, we placed a catheter in the superior vena cava. Cardiac DSA examinations were performed in one hundred and one patients with heart disease. We injected 35 ml of contrast medium at a speed of 18 ml/sec via a catheter introduced in the superior vena cava. DSA images by continuous mode were obtained in the RAO projection for 15-20 sec. Sequential DSA images were observed and analyzed by time-density curves of the regions of interest (ROI) which were placed in the right ventricle (RV) and inferior vena cava (IVC). Doppler echocardiography was performed for 16 cases in which TR was suspected. Of these, phonocardiography with jugular pulse tracing was recorded for 14 and contrast echocardiography were performed for six, respectively. In cases without evidence of TR, regurgitation of contrast medium into the IVC during RV systole was not recorded by the DSA method. In cases of clinically-proven TR, regurgitation into the IVC during RV systole was observed. Thus, this was considered a diagnostic feature of positive TR using the DSA method, and 13 of the 16 cases undergoing Doppler echocardiography were diagnosed as having TR using the DSA method. The severity of TR was categorized as mild, moderate and severe according to analyses of time-density curves. The severity established by the DSA method showed a close correlation with the clinical severity of TR. Doppler echocardiography was negative for TR in two of the 13 cases, but positive for TR in two of the 16 suspected cases only by the Doppler method. In cases of moderate to severe TR diagnosed by the DSA method, jugular pulse tracings showed a regurgitant wave. By contrast echocardiography, TR was evident only in cases of severe TR diagnosed by the DSA method. In conclusion, the DSA method proved useful for diagnosing TR.

Assessment by autonomic blockade of age-related changes of the sinus node function and autonomic regulation in sick sinus syndrome

Age-related changes of the sinus node (SN) function and the autonomic influence on the SN function were evaluated in 65 patients with sick sinus syndrome (range 14 to 84 years). Heart rate (HR), corrected SN recovery time and sinoatrial conduction time were measured before (basic) and after (intrinsic) autonomic blockade (propranolol 0.2 mg/kg plus atropine 0.04 mg/kg intravenously). Percent of autonomic chronotropies of the SN function were calculated by the following formulas: (1)--(intrinsic HR--basic HR/intrinsic HR) X 100; (2) (intrinsic corrected SN recovery time--basic corrected SN recovery time/intrinsic corrected SN recovery time) X 100; (3) (intrinsic sinoatrial conduction time--basic sinoatrial conduction time/intrinsic sinoatrial conduction time) X 100. Basic HR, basic corrected SN recovery time and basic sinoatrial conduction time did not vary with age. Intrinsic HR decreased with age, but this correlation was weak (r = -0.54, p less than 0.001). Intrinsic corrected SN recovery time and intrinsic sinoatrial conduction time tended to increase with age (r = 0.26, p less than 0.05; r = 0.29, p less than 0.05, respectively). Percent chronotropies of HR, corrected SN recovery time and sinoatrial conduction time were negative values in younger patients and positive values in elderly patients; they correlated positively with age (r = 0.59, p less than 0.001; r = 0.60, p less than 0.001; r = 0.43, p less than 0.001, respectively). Thus, the basic SN function did not change with age, while the intrinsic SN function deteriorated with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Classification of hypertrophied hearts in essential hypertension: evaluation by left ventricular wall stress and adrenergic responses

Left ventricular mass, fractional shortening, and end systolic wall stress (mechanical indices) measured by echocardiography and the response of fractional shortening and end systolic wall stress to the infusion of isoproterenol (0.02 microgram/kg/min for 5 min) (a non-mechanical index) were studied in 57 patients (mean (SD) age 49(8)) with essential hypertension. Nineteen patients had subnormal end systolic wall stress (group 1), 25 patients had normal end systolic wall stress and slightly increased left ventricular mass (group 2A), and 13 patients had normal end systolic wall stress and considerably increased left ventricular mass (group 2B). Plasma noradrenaline concentration was higher in group 2B than in the other groups. When end systolic wall stress was greater than 12 g/cm2 this variable showed a significant inverse linear relation with fractional shortening before isoproterenol infusion. The inotropic response to isoproterenol was measured as the increase of fractional shortening corrected for the decrease of end systolic wall stress (delta fractional shortening/--delta end systolic wall stress). The mean (SD) change in delta fractional shortening/--delta end systolic wall stress was significantly larger in group 1 (1.40 (0.60) cm2/g) than in group 2A (0.85 (0.39) cm2/g), and was significantly larger in group 2A than in group 2B (0.56 (0.15) cm2/g). In patients with hypertensive hypertrophy with subnormal end systolic wall stress (inappropriate hypertrophy) the beta adrenergic response is increased; in hypertensive hypertrophy with normal end systolic wall stress (appropriate hypertrophy), however, it is normal, or becomes reduced as plasma noradrenaline increases.

Roles of protein kinases in neurotransmitter responses in Xenopus oocytes injected with rat brain mRNA

Microinjection of rat brain mRNA in Xenopus oocytes induced acetylcholine, neurotensin, serotonin, and glutamate receptors in the cells. These receptors stimulate an intracellular reaction pathway, including G-protein activation, inositol trisphosphate (IP3) formation, and Ca2+-dependent Cl- channels. In the present study, we examined the roles of several protein kinases in these responses by means of inhibitors and activators of these kinases. Isoquinolinesulfonamides, inhibitors of protein kinases, caused no current responses and affected no receptor-mediated responses when injected into the oocytes at low doses (30-50 pmol), which inhibit cyclic nucleotide-dependent kinases or kinase C specifically, but abolished the receptor-mediated responses at a higher dose (300 pmol), which inhibit most protein kinases nonspecifically. Calmodulin inhibitors blocked the receptor-mediated responses strongly. Activation of cyclic nucleotide-dependent kinases or kinase C by injection of cAMP (or cGMP) or perfusion with phorbol esters caused no direct current responses but suppressed receptor-mediated responses. Current responses triggered by IP3 injection were not suppressed by these treatments. These results suggest that cAMP- (or cGMP-)dependent kinases or kinase C may not be involved in the pathway directly but may modulate it by inhibiting the initial part of the pathway (receptors, G-proteins, and/or phospholipase C), and they suggest that calmodulin may most likely be involved in the activation of Ca2+-dependent Cl- channels.

[Cases of severe methyl bromide poisoning residing above a warehouse]

Methyl bromide has been widely used in Japan to fumigate grains and wood. One death and 3 cases of hospitalization resulted from exposure to methyl bromide at place of residence. These 4 cases were not employed and were members of one family living above a warehouse, the ground level of this building was a warehouse where herbs were stored and the second floor was their living area. On the 13th of May 1978 at 7:00 p.m., the herbs were fumigated with methyl bromide gas. The fumigator used 15 kg of methyl bromide (2 cylinders), a quantity far greater than usual. It is assumed that the concentration in the warehouse was between 10,000-15,000 ppm. Early in the morning on the 16th of May (3 days later), one of the family members, a 12-year-old girl, developed severe convulsions, and later 2 others also had severe convulsions, while the other suffered from marked mental confusion. The serum or plasma bromide ion level ranged from 280 to 600 ppm. The results of the clinical laboratory test showed that GOT exceeded the normal level in 3 out of the 4 cases. Moreover, LDH activity was above the normal range in 3 cases and CPK activity was increased in all the cases.

The prognostic significance of left ventricular response to isoproterenol infusion in patients with dilated cardiomyopathy

To evaluate the prognostic value of the left ventricular response to isoproterenol infusion in patients with dilated cardiomyopathy (DCM), 25 patients, 17 men and eight women, were studied. According to responses of left ventricular function to isoproterenol (0.02 microgram/kg/min), the patients were classified in two groups: the normal response group, in which fractional shortening increased by more than 10% (n = 10); and the low response group, in which fractional shortening increased by 10% or less (n = 15). A follow-up spanning four to 40 months with an average of 21 months disclosed that six patients died, two deteriorated, and six had no change in the low response group, while seven patients were improved, three stabilized, and no one deteriorated or died in the normal response group. There was a difference in the clinical courses of the two groups. Thus, the left ventricular response to isoproterenol proved useful in predicting the course of DCM.