Diazepam potentiates postsynaptic inhibition in bulbar respiratory neurons of cats

The purpose of this study was to assess the effect of benzodiazepine on inhibitory postsynaptic potentials (IPSPs) of medullary respiratory neurons in decerebrate, paralyzed cats. Diazepam (0.05 and 0.1 mg/kg i.v.) reversibly increased the IPSP waves occurring during the inactive phase of the respiratory cycle in all inspiratory and postinspiratory neurons examined. Input resistances of these neurons were reduced at that phase. The reversal potential for the IPSP wave was unaltered. Intracellular injection of chloride ions reversed the IPSP to depolarization, and diazepam produced a purely depolarizing effect. The drug effects observed during the active phase of each neuron include a decrease in the firing rate and a shortening of the burst activity. The firing threshold and shape of these spikes, however, remained unaltered. These results suggest that diazepam depresses the bulbar respiratory neuronal activities specifically by potentiating the periodic postsynaptic inhibition.

Microiontophoresis of flurazepam on inspiratory and postinspiratory neurons in the ventrolateral medulla of cats: an intracellular study in vivo

Effects of flurazepam on the periodic inhibitory postsynaptic potentials (IPSPs) and on the action of locally applied gamma-aminobutyric acid (GABA) were studied in bulbar respiratory neurons of decerebrate cats using concentric multibarrelled electrodes for intracellular recording and extracellular iontophoresis. Iontophoresis of flurazepam augmented spontaneous IPSPs and increased the hyperpolarization induced by GABA. Iontophoretic application of bicuculline suppressed the action of flurazepam. The reversal potential for spontaneous IPSPs was similar to that for the GABA-response. Intracellular Cl- injection shifted both the IPSP wave and the GABA response in a depolarizing direction. Flurazepam enhanced these depolarizing responses. These results suggest that GABA mediates the postsynaptic inhibition in bulbar respiratory neurons.

[A multicenter clinical trial of SMS 201-995 (octreotide acetate) in acromegaly and gigantism]

Sixty-four patients with active acromegaly and three patients with gigantism were treated with the long acting somatostatin analog SMS 201-995 (50-500 micrograms, sc, every 6-12 h or 150-880 micrograms daily by intermittent sc infusion, for up to 114 weeks). The fasting plasma GH levels were significantly suppressed (less than 50% of the values before treatment) in 49 patients and became normal in 18 patients. Suppression of GH secretion was associated with normalization of plasma somatomedin-C levels (14 out of 30 cases) and significant clinical improvement such as disappearance of headache and decrease of excessive sweating. Shrinkage of pituitary tumors as determined by computed tomography and/or magnetic resonance imaging studies occurred in 11 out of 40 cases. Side effects were minimal and tolerable. SMS 201-995 appears to be an effective agent for the treatment of acromegaly and gigantism.

[Monitoring of somatosensory evoked potentials during extracranial revascularization]

Intraoperative somatosensory evoked potentials (SEPs) were measured in 17 patients during 21 extracranial revascularization and related procedures. The operations included 13 carotid endarterectomies (CEAs), two cervical internal carotid ligations, one vertebral artery (VA) clipping, one VA-common carotid artery (CCA) transposition, and four temporary balloon occlusion tests (TBOTs). Three of the 13 CEAs (23%) showed reduced amplitude and delayed latency of primary cortical SEPs during clamping of the carotid artery, followed by their recovery after emplacement of the internal shunt. Flattening of SEPs during clamping of the CCA was observed in the case of VA-CCA transposition; however, SEPs returned to normal immediately after insertion of a balloon indwelling shunt into the CCA. One of the four TBOTs showed alteration of SEPs during balloon occlusion of the subclavian artery proximal to the origin of the VA. In the others, SEPs remained stable during the entire procedure. Only one transient intraoperative ischemic complication was encountered among the cases of CEA. It was detected through flattening of SEPs, which led to the discovery of an internal shunt obstruction. Carotid stump pressure was also measured in 12 CEAs and two TBOTs, and seven of these 14 had pressure less than or equal to 50 mmHg. Four of the seven had carotid stump pressure less than or equal to 30 mmHg, and three of these four also showed altered SEPs. SEPs remained stable if the collateral flow was sufficient during vascular occlusion and showed obvious alteration when the blood flow was reduced to below the threshold. The authors conclude that monitoring of SEPs during extracranial revascularization is very useful.

Possible association of aldosterone producing adenoma and non-functioning adrenal tumor

A 37-year-old woman presented with hyperaldosteronism, suppressed renin levels, and a left adrenal mass on CT scanning. Selective adrenal venous sampling indicated a marked rise of the aldosterone level in the right adrenal vein, while the level in the left vein was low. On laparotomy, an aldosterone producing adenoma (APA) of 12x10x5 mm in size was found in the right adrenal gland and was resected, while the left mass was left in situ. The post-operative course showed normalization of both the clinical and biochemical features of primary aldosteronism, with no sign of recurrence or of enlargement of the remaining adrenal mass in 2.5 years of follow up, suggesting the possible coexistence of a "non-functioning" tumor. This case demonstrates the importance of adrenal venous sampling for the localization of APA particularly since the presence of the APA may be masked by a visualized but unrelated adrenal mass.

Development of coronary heart disease in familial hypercholesterolemia

We studied the development of coronary artery disease in 10 homozygous and 692 heterozygous patients with familial hypercholesterolemia. Seventy-five (22%) male heterozygotes and 35 (10%) female heterozygotes were affected by myocardial infarction, which was first noted in men in the 3rd decade of life and in women in the 4th decade of life. Thirty-eight (70%) out of the deceased 54 heterozygous patients died of coronary heart disease. The mean age at death was significantly less in male heterozygotes (54 years) than in female heterozygotes (69 years). Five homozygous and 105 male and 56 female heterozygous patients received coronary angiographic evaluation. The regression equations between age (X) and coronary stenosis index (Y) obtained by assigning score (0 to 5) to each of 15 coronary artery segments were Y = 1.57X - 20.43 (r = 0.956, p less than 0.05) in the homozygotes, Y = 0.52X - 9.11 (r = 0.438, p less than 0.001) in the male heterozygotes, and Y = 0.47X - 12.54 (r = 0.343, p less than 0.01) in the female heterozygotes. From these data, we can assume that coronary artery stenosis detectable by angiography will occur after 17 and 25 years of age in male and female heterozygotes, respectively, and the treatment of heterozygotes with lipid-lowering drugs can be delayed until late adolescence.

A young type III hyperlipoproteinemic patient associated with apolipoprotein E deficiency

A 13-year-old female patient had noticed tuberoeruptive xanthomas since 3 years of age. Her serum, VLDL, and IDL cholesterol levels were high (348, 158, and 60 mg/dL, respectively), while LDL and HDL cholesterol levels were 56 and 62 mg/dL, respectively. VLDL-cholesterol/serum triglyceride ratio was extremely high (0.86), suggesting type III hyperlipoproteinemia (HLP). Her apo E was undetectable by the single radial immunodiffusion studies and SDS-polyacrylamide gel electrophoresis. Her parents showed hypertriglyceridemia and her two siblings were normolipidemic, and their apo E levels were normal. Genomic DNA digested with BamHI or EcoRI did not show gross differences in the restriction fragment length between the apo-E-deficient patient and normal controls. Thus, apo E deficiency may be characterized by early appearance of clinical manifestations of type III HLP and higher VLDL-cholesterol/serum triglyceride ratio.

Disopyramide induces insulin secretion and plasma glucose diminution: studies using the in situ canine pancreas

The mechanism of disopyramide-induced hypoglycemia, a life-threatening complication in the antiarrhythmic drug treatment, is still controversial. To elucidate this, we have evaluated plasma insulin (IRI) and glucagon (IRG) responses in the pancreatic vein (PV) of the in situ pancreas as well as responses of plasma IRI, IRG, and glucose in the femoral artery (FA) to disopyramide phosphate administration in anesthetized dogs. First, infusion of disopyramide at a dose of 50 mg for ten minutes directly into the pancreatic artery, but not the vehicle, increased significantly plasma IRI concentration in the PV (P less than .05 or less), where the IRI response started within three minutes and reached a peak of 2.8-fold preinfusion value at 30 minutes after starting the infusion (n = 7). Plasma IRI concentration in the FA also increased slightly but significantly (P less than .05). Plasma IRG concentration in the PV initially decreased significantly (P less than .05 or less) and in the FA at one point (P less than .05) during the infusion, and then increased significantly after cessation of the infusion, showing a peak of 1.9-fold preinfusion value at 60 minutes in the PV and the FA (P less than .05). Plasma glucose concentration in the FA decreased slowly and significantly after the infusion (P less than .05 or less) and fell by 16% of the baseline value at 60 minutes (P less than .05). Second, serum disopyramide concentration of 13.7 +/- 2.8 micrograms/mL at ten minutes, which corresponds to a twofold to threefold concentration of the human therapeutic level (n = 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical characterization of a digitalis-like substance in human urine, partially purified by high pressure liquid chromatography

We have partially purified a digitalis-like extract from human urine by means of high pressure liquid chromatography (HPLC). Four fractions, giving positive activity for the cross-reaction in the digoxin radioimmunoassay, Na-K-ATPase inhibition or competition with ouabain binding to its receptor, were detected on HPLC. Among these fractions, the first (F-1) was shown to contain the principle fraction, sharing all the activities, and to exhibit quite similar characteristics to ouabain in the modes of Na-K-ATPase inhibition, ouabain displacement activity and positive inotropic action.

Impairment of modulating role of testosterone in growth hormone response to clonidine in essential hypertension

To investigate the effects of endogenous testosterone (T) on the responsiveness of plasma growth hormone (GH) to central alpha 2 adrenergic stimulation, we administered clonidine (0.15 mg, p.o.) to 16 male patients with essential hypertension (EHT) and 13 age-matched male normotensive controls (NT). Although the basal T level was correlated with the peak GH increment (r = 0.709, p less than 0.01) and with the area under curve of GH (r = 0.714, p less than 0.01) in the NT group, no such correlations were seen in the EHT group. The present study confirmed the potentiating role of endogenous T in GH responsiveness to clonidine in male NT. The lack of correlation between T and GH response in EHT suggests a neuroendocrine disturbance in modulation by T of the GH response to central alpha 2 adrenergic stimulation.

Electrophysiological properties of respiratory laryngeal motoneurons and effects of thiopental

Transmembrane potentials of the respiratory laryngeal motoneurons were recorded in decerebrate, vagotomized and paralyzed cats. Twenty inspiratory and thirteen postinspiratory neurons were identified. Periodic membrane potential (MP) fluctuations as well as patterns of postsynaptic potentials (PSPs) were characterized in each type of neurons by measuring the input resistance and injecting Cl- to reverse inhibitory PSPs. On the basis of PSP patterns, two subtypes of inspiratory neurons could be distinguished. Thiopental (2-3 mg/kg, i.v.) produced depolarization together with reduction of firing in most laryngeal neurons. Excitatory and inhibitory PSPs were both depressed and MP fluctuations became smaller in each phase of the respiratory cycle. Elevation of the firing threshold and separation of IS-SD spikes often occurred after thiopental. These results suggest that thiopental depresses the laryngeal motoneuron through inhibition of synaptic transmission and of spike generation.

Agonist-induced substance P receptor down-regulation in rat central nervous system

Rat brain slices were incubated with substance P (SP), and the SP receptors on the membranes from those slices were characterized by a 3H-SP binding technique. The number of substance P receptors measured in the extensively washed membrane preparations pretreated with 3 x 10(-5) M SP was reduced by 30% compared with that in nontreated membranes. This reduction was dependent on the incubation time and temperature. The metabolic inhibitors sodium azide and 2,4-dinitrophenol protected SP receptors from the reduction. The characteristics of 3H-SP incorporation into rat brain slices were similar to those of SP receptor down-regulation, that is, the 3H-SP incorporation was time, temperature, and energy dependent. Thus these results indicate that the processes of ligand incorporation and receptor down-regulation are closely associated phenomena. These observations may be important in elucidating the phenomenon of SP-induced desensitization.

[Aldosterone metabolites in spontaneously hypertensive rats]

Several aldosterone metabolites are now known to possess some mineralocorticoid activities. In order to test the hypothesis that these metabolites could contribute to the pathogenesis of hypertension, we studied the aldosterone metabolism in SHR in vitro and in vivo. In vitro experiment, male SHR and WKY rats of 4 and 15 weeks of age were used. The microsome, cytosol and heavy mitochondria fractions from liver and kidney were isolated by ultracentrifuge. 10mg protein/ml of each subcellular fraction was incubated with 3H-aldosterone in Tris-HCl buffer at pH 7.4 containing NADPH, glucose-6-phosphate (G-6-P) and G-6-P dehydrogenase as described by Morris, D.J. et al. (Hypertension, 5 (suppl. I]: I-35-I-40, 1983.). Aldosterone and its metabolites synthesized were extracted with Sep-pak C18 cartridges and separated by HPLC on a reverse phase column. In vivo experiments, the urine of male SHR and WKY rats of 15 weeks old injected 10 microCi 3H-aldosterone intraperitoneally was collected for 48 hours, extracted and analyzed by HPLC. Peaks of steroids from SHR were compared with those from WKY. Incubation of aldosterone with liver microsomes yielded at least 10 polar and 3 less polar metabolites (A-ring reduced metabolites). SHR liver microsomes synthesized larger amounts of 3 polar metabolites than WKY liver microsomes. Liver cytosol, liver heavy mitochondria and kidney subcellular fractions mainly synthesized less polar metabolites, but failed to synthesize as much polar metabolites as liver microsomes. Kidney microsomes and cytosol from 4 weeks old SHR synthesized larger amounts of less polar metabolites compared to those from WKY. In vivo experiment, SHR of 15 weeks of age excreted larger amounts of 2 polar metabolites than WKY. The present study suggests that the difference of metabolism of aldosterone between SHR and WKY observed from an early stage in the liver and the target organ, kidney, may be associated with hypertension or its causative factors, and confirms that aldosterone will be metabolized to several polar and less polar forms by rat liver and kidney subcellular fractions.

Biological activity of partially purified digitalis-like substance and Na-K-ATPase inhibitor in rats

In order to study the biological activity of endogenous digitalis-like substance (DLS) and Na-K-ATPase inhibitor (ATPI), human urine was partially purified and administered to rats, and its effects on the urinary volume, urinary Na excretion and blood pressure (BP) were determined. In addition, the effect on myocardial Na-K-ATPase activity was also measured. After the extraction of 40L of urine with a reversed phase cartridge column (S-fraction), 20 ml of chloroform was added and extraction was repeated. The chloroform layer was applied to an open silica gel column, and at a fraction with ethylacetate: methanol (60: 40, T-1 fraction), DLS and ATPI were eluted at the highest concentration. The water layer was treated with charcoal (D-1 fraction). The acute administration of K-1, T-1 fraction to rats in vivo caused significant rises in urinary volume, urinary Na excretion and BP. In chronic administration of K-1 fraction, urinary Na excretion was significantly elevated and myocardial Na-K-ATPase activity was also significantly suppressed. These results suggest that DLS and ATPI cause increase in the urinary volume and urinary Na excretion and also possess a hypertensive action; and moreover, these substance may affect the heart like cardiotonic steroids and regulate BP by increasing cardiac contractility.

A new technique for repair of mitral insufficiency caused by ruptured chordae of the anterior leaflet

Prolapse of the anterior leaflet of the mitral valve is the result of ruptured chordae, elongated chordae, or elongated or ruptured papillary muscle. Several techniques have been described for the correction of mitral valve insufficiency. However, when there is severe rupture of the chordae, the most widely accepted solution is valve replacement. We describe a technique for the creation of a neochorda with a strip of tissue from the anterior leaflet of the mitral valve. This technique was used in two patients with severe mitral valve regurgitation. Formation of a neochorda and placement of a Carpentier ring to remodel the anulus obviated the need for a valve replacement. Both patients had an uneventful recovery. Studies performed 3 and 4 months postoperatively showed competent and well-functioning valves. One patient required a valve replacement for acute mitral insufficiency 5 years later, but the other patient was doing well 3 years after the operation. Despite the limited experience, we believe this technique offers a reasonable alternative to valve replacement.

Removal of apolipoprotein E-enriched high density lipoprotein by LDL-apheresis in familial hypercholesterolaemia: a possible activation of the reverse cholesterol transport system

The presence of apo E-containing HDL in familial hypercholesterolaemia was investigated and its removal by LDL-apheresis using a dextran sulphate cellulose column was demonstrated by measurement of the apo E/apo A-I molar ratio of serum and by nondenaturing polyacrylamide gel electrophoresis followed by immunoblotting. The molar ratios of apo E/apo A-I in the density greater than 1.063 kg/l fraction of serum obtained from two homozygous patients with familial hypercholesterolaemia were higher (0.021 and 0.030) than that from normal subjects (mean +/- SE 0.011 +/- 0.002) (P less than 0.05). Polyacrylamide gel electrophoresis and immunoblotting showed an increase in apo E-containing HDL similar to HDL2, in the plasma obtained from the homozygous patient with familial hypercholesterolaemia. The increased amounts of apo E-enriched HDL were removed from plasma by adsorption with a dextran-sulphate cellulose column. These results suggested that LDL-apheresis using the dextran-sulphate cellulose column, may cause an increase in the turnover rate of the apo E-containing HDL and thus facilitate cholesterol removal from the peripheral tissues.

Quantitation of myocardial fibrosis and its relation to function in essential hypertension and hypertrophic cardiomyopathy

Myocardial interstitial fibrosis is an important microscopic feature of hypertrophic cardiomyopathy. To determine whether interstitial fibrosis of the myocardium in hypertrophic cardiomyopathy and essential hypertension differ in quality or quantity, and to determine whether fibrosis affects cardiac function directly, we measured the percentage of fibrosis in patients of both categories and compared the severity of fibrosis with several cardiac functions. Left and right ventricular endomyocardial biopsies were performed in 25 patients with essential hypertension and in 19 patients with hypertrophic cardiomyopathy. Interstitial fibrosis was classified into four different microscopic types, and the percentage of total and of each type was calculated using the point-counting method. Although the percentage of total fibrosis was similar between the two groups, the type of fibrosis was different. There was no correlation between the percentage of total fibrosis and the mean size of myocytes in either group. Although there was a significant correlation between the percentage of total fibrosis and the thickness of the interventricular septum in hypertrophic cardiomyopathy, such correlation was lacking in hypertension. There was no correlation between the percentage of total fibrosis and the ejection fraction, cardiac index, or left ventricular end-diastolic pressure in either group. We concluded that the amount of myocardial interstitial fibrosis in hypertrophic cardiomyopathy is no greater than that in essential hypertension, but the type of fibrosis is different. Furthermore, in subjects in whom the ejection fraction is normal or only slightly decreased, fibrosis does not influence global cardiac functions.

Comparative effects of captopril and nifedipine on split renal function in renovascular hypertension

Comparative effects of angiotensin-converting enzyme inhibitor (ACEI) captopril and calcium entry blocker nifedipine on the split renal function were studied in six patients with renovascular hypertension (RVH) with unilateral stenosis (38 +/- 5 years). Both captopril and nifedipine showed potent antihypertensive effects; the mean arterial pressure was reduced from 131 +/- 16 to 105 +/- 8 mm Hg (P less than 0.001) by captopril, and from 128 +/- 15 to 109 +/- 11 mm Hg (P less than 0.001) by nifedipine. The glomerular filtration rate (GFR) in the stenotic kidney was 24 +/- 6 mL/min, which decreased to 11 +/- 2 mL/min (P less than 0.01) during captopril administration, and only slightly decreased (18.8 +/- 5 mL/min) during nifedipine administration. The effective renal plasma flow (ERPF) increased in the nonstenotic kidneys in response to both drugs. These results show that angiotensin II rather than renal perfusion pressure may be important for maintaining GFR in the stenotic kidney, and further suggest that nifedipine may be used relatively safely in treating patients with RVH, although caution should be exercised in terms of their ability to preserve the renal function in individual kidneys.

[Serial changes in left ventricular configuration and function in hypertrophic cardiomyopathy]

Fifteen patients, 12 males and three females, with hypertrophic cardiomyopathy (HCM) including three of obstructive type (HOCM) were investigated to observe the long-term course of HCM. Left ventriculography and bi-ventriculography were performed twice serially in all cases. We studied the correlations between the serial ECG changes, especially the negative T wave, and the left ventricular configuration, wall thickness, and left ventricular function. Serial ECG changes included: 1) negativity of the T wave which developed or increased concomitantly with increased voltages of SV1 + RV5 (A-1 group: five cases), 2) the negativity decreased or resolved with decreased voltages of SV1 + RV5 (A-2 group: four cases), and 3) insignificant changes of both T waves and SV1 + RV5 (B group: six cases). In the right oblique views at end-diastole, the configuration of the left ventricle was classified in three forms; (1) spade form (S), (2) round form (R), and (3) intermediate form (SR). The results were as follows: 1. The A-1 group showed increased thickness of the apical and anterior walls, but the thickness of the posterior wall and interventricular septal wall did not change serially. In three cases, the thickness of the interventricular septum showed mild hypertrophy at the initial and final observations. The configuration changed from the R or SR form to the S form. Diastolic dysfunction (peak dV/dt/V, peak dV/dt/EDV) was progressive, but end-diastolic volume and ejection fraction did not change. 2. The A-2 group showed the significantly decreased thickness of the apical and anterior walls. The thicknesses of the posterior wall and interventricular septal wall tended to decrease in all cases. In three cases (75%), the interventricular septal wall was markedly hypertrophied on the initial observation. The configuration changed from the S or SR form to the R form. Left ventricular diastolic function and ejection fraction decreased significantly and end-diastolic volume increased. Two cases showed clinical pictures of dilated cardiomyopathy at the final observation. 3. In the B group, there were no marked changes in wall thickness, left ventricular configuration, or systolic and diastolic functions. In conclusion, serial changes in left ventricular configuration, wall thickness, especially of the anterior and apical walls, and left ventricular function were all compatible with the serial changes of the ECG in hypertrophic cardiomyopathy.(ABSTRACT TRUNCATED AT 400 WORDS)

[Regression of giant negative T waves in hypertrophic cardiomyopathy: cases simulating either dilated cardiomyopathy or severe coronary artery stenosis]

Two cases of hypertrophic cardiomyopathy (HCM), in whom giant negative T waves resolved during 10 years, are reported. Case 1: A 33-year-old man was admitted in 1975 for careful evaluation because of an ECG abnormality. The ECG revealed a giant negative T wave (GNT) in V5 (-15 mm) and high voltage (SV1 + RV5 = 81 mm). The thickness of the apical wall was 18 mm; the anterior wall, 12 mm; the posterior wall, 16 mm; and the interventricular septum, 17 mm on the left ventriculogram and biventriculogram. The coronary angiogram was normal. From these data, this patient was diagnosed as having HCM. However, follow-up studies disclosed resolution of the GNT with decreased high voltage (SV1 + RV5 = 26 mm). The catheterization performed in 1985 showed a decrease of wall thickness: the apical wall to 10 mm; the anterior wall, 9 mm; the posterior wall, 14 mm; and the interventricular septum, 14 mm. Ejection fraction was markedly decreased from 79.8% to 27.1%, and the wall motion was generally reduced. The coronary angiogram was normal. These findings resemble the clinical pictures of dilated cardiomyopathy (DCM). Case 2: A 58-year-old man was admitted in 1974 because of easy fatiguability. His ECG revealed a GNT in V4 (-10 mm) and high voltage (SV1 + RV5 = 75 mm). The patient was diagnosed as having HCM by cardiac catheterization, right ventricular biopsy and other procedures. In 1985, the depth of the GNT and the voltage of SV1 + RV5 regressed significantly (SV1 + RV5 = 26 mm). The thickness of the apical wall was, 12 mm; the anterior wall, 19 mm; the posterior wall, 13 mm; and the interventricular septum 14 mm during recatheterization. Coronary angiography disclosed stenoses of the left main trunk (75%), the left anterior descending artery (99%) and the left circumflex artery (50%). The right coronary artery was totally occluded. In conclusion, these two cases of HCM had similar changes in their ECG during long-term follow-up studies, but the process was different. One case finally showed clinical pictures of DCM; the other, severe coronary stenoses. These suggested that blood flow to the myocardium is an important determinant for the development of clinical features simulating DCM in cases with HCM.