[Features of digitalization in the ECG image and the blood digoxin level].
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
A Januszewicz
Publications and source records attributed to A Januszewicz.
Magnetic resonance imaging differentiation of adrenal masses at 1.5 T: T2-weighted images, chemical shift imaging, and Gd-DTPA dynamic studies.
The purpose of our study was to assess the potential role of spin-echo (SE), chemical shift, and gadolinium-enhanced magnetic resonance imaging (MRI) in the differentiation of adrenal masses. Seventy-two adrenal masses (26 nonhyperfunctioning adenomas, 16 aldosterone-secreting adenomas and 6 other different benign cortical masses, 18 pheochromocytomas, and 6 malignant masses) in 63 patients were evaluated with spin-echo sequences, chemical shift imaging (CSI) and gadolinium diethylenetriamine penta-acetic acid (Gd-DTPA) dynamic studies. Ratios and indices of signal intensity for all examined MRI methods were calculated and examined for significance of difference between different types of adrenal masses. Quantitative magnetic resonance evaluation of adrenal masses showed significant differences (at least alpha < 0.01) between nonhyperfunctioning adenomas vs. pheochromocytomas or vs. malignant lesions or vs. aldosterone-secreting adenomas and between pheochromocytomas vs. malignant lesions. The most specific indicators of adrenal mass character proved to be the CSI ratio based on opposed-phase and in-phase two-dimensional fast low-angle shot (FLASH) images, reflecting lipid content in the lesion, and Gd-DTPA dynamic studies ratios reflecting contrast agent inflow and washout in the lesion: WoMAX/LAST and Dyn1.2-3.2. There was no overlap of CSI ratio between adenomas and pheochromocytomas. The overlap of ranges of CSI ratio between nonhyperfunctioning adenomas and aldosterone-secreting adenomas was only 18.5%. There was no overlap of WoMAX/LAST ratio between adenomas and pheochromocytomas, or adenomas and malignant lesions. The overlap of ranges of Dyn1.2-3.2 ratio between pheochromocytomas and malignant lesions was only 17.6%. MRI enables good visualization and specific characterization of adrenal masses. The optimal MRI protocol for the adrenal region is presented.
Adenoma↗
Purification, sequencing and synthesis of natriuretic and vasoactive rat atrial peptide.
Mammalian atria contain potent natriuretic and diuretic substances which exist in high- and low-molecular-weight forms and which appear to be associated with atrium-specific granules. The natriuretic effect of atrial extract is largely accountable for by its renal haemodynamic effects; atrial extracts also antagonize hormone- and non-hormone-induced contraction of the isolated rabbit aorta and isolated rat kidney vasculature. We have completely purified a low-molecular-weight natriuretic and vasoactive substance from rat atria and characterized it as a 24-amino acid peptide. Synthetic peptide, produced by solid-phase synthesis, mimics biological effects of crude atrial extract and purified peptide; its activity is enhanced by slow oxidation, suggesting a disulphide (Cys 4-Cys 20) configuration for the native peptide. If secreted into blood, this atrial natriuretic peptide (' auriculin B') could be a novel peptide hormone of considerable importance to renal and cardiovascular homeostasis.
Amino Acid Sequence↗
Atrial natriuretic factor inhibits angiotensin-, norepinephrine-, and potassium-induced vascular contractility.
We have previously shown that the natriuretic effect of rat atrial extract (AE) may be due, perhaps entirely, to its powerful renal hemodynamic actions. The present study was undertaken to test the hypothesis that mammalian atria contain a substance that behaves as a functional antagonist of endogenous vasoconstrictors, by examining the direct effects of AE and extensively purified atrial "natriuretic" factor on the contractile response of rabbit aortic rings to angiotensin II (AII), norepinephrine (NE), and K+-induced depolarization. Dose-response curves to AII and NE (i.e., change in tension vs log hormone concentration) were determined in the absence or presence of boiled AE or ventricular extracts (VE). Increasing concentrations of boiled AE caused a progressive right-ward shift of the AII and NE dose-response curves, whereas VE was without effect. A similar inhibitory effect was produced after extensive purification of atrial natriuretic factor by gel filtration and reversed-phase high performance liquid chromatography (HPLC). It appeared that this factor antagonized AII-induced contractility to a greater degree than that of NE. Moreover, the partially purified factor also inhibited the contraction induced by depolarization with 15 mM KCl in a concentration-dependent manner. These studies show that a substance present in the atria, but not ventricles, blocks both hormone- (receptor) and depolarization- (nonreceptor) induced vasoconstriction in aortic rings. Moreover, this antagonism is retained following extensive purification of an atrial factor that induces natriuresis in the intact rat and isolated rat kidney, suggesting that both the vasoactive and natriuretic properties of AE may reside in a single substance.(ABSTRACT TRUNCATED AT 250 WORDS)
Angiotensin II↗
Rat platelets activate high molecular weight atrial natriuretic peptides in vitro.
Evidence suggests that the more biologically active low molecular weight forms (less than 10,000) of rat atrial natriuretic peptides are proteolytically derived from a less active precursor of higher molecular weight. Conversion and activation could occur within the myocyte as well as during circulation. The present study found that in vitro rat blood and platelets were capable of converting the high molecular weight atrial natriuretic peptides (greater than 10,000) to low molecular weight atrial natriuretic peptides within minutes and that enhanced biological activity attended the conversion. Rat high molecular weight peptides were partially purified by gel filtration, lyophilized, and reconstituted in Krebs-Ringer bicarbonate buffer. One milliliter of fresh rat blood was incubated with the high molecular weight peptides at 37 degrees C for 2 minutes. After centrifugation, the supernatant was fractionated on Sephadex G-75. Natriuretic activity was determined by bioassay in anesthetized rats. In contrast to the results following incubation of high molecular weight peptides in Krebs-Ringer bicarbonate buffer alone, which showed that 95% of the natriuretic activity remained in the high molecular weight peptide region, the natriuretic activity of the blood-treated high molecular weight peptides eluted almost exclusively in the low molecular weight peptide region, which indicates conversion. Blood was separated into plasma, erythrocytes, lymphocytes, and platelets. Conversion of high to low molecular weight peptides occurred only after incubation with platelets. Compared with control high molecular weight peptides, rat platelet-treated high molecular weight peptides had significantly greater activity in relaxing histamine-contracted rabbit aortic smooth muscle (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Effects of vasopressin and V1 receptors blockade on blood pressure and heart rate in spontaneously hypertensive rats.
The aim of the present study was to compare effects of intravenous infusion of vasopressin AVP and V1 receptors blockade on blood pressure and heart rate in normotensive (WKY) and spontaneously hypertensive (SHR) rats. A 20 min vasopressin infusion (1.2 ng/kg/min) elicited significantly greater increase in mean blood pressure (MP) in SHR than in WKY. Heart rate was significantly reduced in SHR while nonsignificantly in WKY. A 20 min dEt2 AVP (V1 antagonist) infusion (0.5 microgram/kg/min) elicited significant decrease in MP and increase in heart rate (HR) in SHR, but produced no effect in WKY. The data indicate that SHR are more susceptible to pressor and hypotensive effects of sustained elevation of AVP and AVP antagonist. The results support the hypothesis that AVP may contribute to pathogenesis of hypertension.
Animals↗
[Digoxin-like substance in blood and hypertension in dialysed patients with chronic renal failure].
Concentration of free serotonin, adrenaline, noradrenaline, aldosterone and plasma renin activity have been assayed in blood of 18 patients with the primary arterial hypertension (WHO stage I) and in 10 healthy volunteers. It was found that blood free serotonin and noradrenaline are increased in hypertensive patient. No difference in adrenaline and aldosterone levels and plasma renin activity was seen. No significant correlation between free serotonin and assayed hormones was noted.
Adult↗
[Pseudo-pheochromocytoma].
Explore the source record for details and available documents.
Adrenal Gland Neoplasms↗
[Endothelin--a new pressor hormone].
Explore the source record for details and available documents.
Animals↗
[Atrial natriuretic peptide and arterial hypertension].
Explore the source record for details and available documents.
Atrial Natriuretic Factor↗
[Effect of atrial natriuretic factor on arterial blood pressure and frequency of heart contraction in rats with genetically determined hypertension and in normotensive rats].
An effect of peptide released by the heart atria of mammals and called the atrial natriuretic factor (ANF) on blood pressure and heart contractions was studied in rats with genetically determined arterial hypertension (SHR) and in normotensive Wistar-Kyoto rats (WKY). Nine male SHR rats and 11 male WKY rats, aged between 12 and 16 weeks, were given normal saline infusion for 30 minutes through implanted catheters to both ulnar vein and artery. Then, an infusion of ANF at the rate of 0.3 microgram/kg per hour followed for 35 minutes. An infusion of ANF produces significant decrease in the mean arterial blood pressure, systolic and diastolic pressures without significant effect on pulse pressure and heart contractions. AFN infusion with the same rate did not produce any significant differences in the arterial blood pressure and heart contractions in Wistar-Kyoto rats. The obtained results suggest that ANF may play a role in pathogenesis of the arterial blood hypertension.
Animals↗
Pressor responsiveness to vasopressin in spontaneously hypertensive rats.
The present study was designed to find out whether pressor responsiveness to vasopressin (AVP) is altered in spontaneously hypertensive rats (SHR) in comparison with their normotensive controls (WKY). Blood pressure and heart rate changes after injection of graded doses of 2.5, 5.0 and 10.0 ng of AVP (Calbiochem) i.v. were compared in 9 conscious, unrestrained spontaneously hypertensive (SHR) and 11 normotensive Wistar Kyoto (WKY) rats, chronically instrumented with venous and arterial catheters. The threshold dose necessary to elicit a significant increase in blood pressure and reduction of heart rate was lower in WKY than in SHR. At each dose level the blood pressure elevation persisted for a longer period in WKY than in SHR. Bradycardia was greater in WKY than in SHR both in absolute terms and in relation to the blood pressure increase. Thus, the results reveal diminished pressor responsiveness to moderate doses of AVP in SHR in spite of suppressed reflex bradycardia. It is suggested that the peripheral action of AVP on the vascular system is attenuated in SHR.
Animals↗
Vasorelaxant and natriuretic activities of synthetic atrial peptides.
The vasorelaxant and natriuretic activities of synthetic atrial natriuretic peptides (ANF) were compared by measuring relaxation of histamine-contracted rabbit aortic rings and changes in urinary sodium excretion in anesthetized rats. The peptides studied and their relation to pro-ANF were: atriopeptins (AP) I, II and III (ANF 103-123, 103-125, 103-126), cardionatrin (CN) (ANF 99-126), alpha-human atrial natriuretic polypeptide (alpha-hANP) (human 99-126) and a fragment of the last (hFrag) (human ANF 105-126). The concentration causing 50% relaxation (EC50) in the vasorelaxant assay for API was greater than that of the other peptides (p less than 0.05). The EC50 for hFrag was 20 times greater than that of alpha-hANP, but this difference was not statistically significant. API caused less natriuresis compared with the other peptides (p less than 0.05). The natriuresis induced by CN was significantly greater than that of the other peptides at the 485 pmol dose. These results indicated that, except for API, the peptides studied has similar vasorelaxant and natriuretic activities.
Animals↗
Blood pressure responses to substances interfering with nitric oxide formation, cyclooxygenase and converting enzyme activities and vasopressin V1 receptors blockade in conscious spontaneously hypertensive and normotensive rats.
The aim of the study was to investigate to what extent inhibition of nitric oxide (NO) formation, cyclooxygenase and converting enzyme activities and vasopressin V1 receptors blockade affects the cardiovascular system in conscious, freely moving normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. The experiments were performed on 33 WKY and on 33 SHR. In series 1 (8 WKY and 8 SHR) animals received bolus injection of N omega-nitro-L-arginine - NLA (10 mg/kg), in series 2 (6 WKY and 6 SHR) bolus injection of indomethacin (10 mg/kg). In series 3 (8 WKY and 8 SHR) the animals received captopril as initial bolus (1 mg/kg) followed by constant infusion (1 mg/kg/min), in series 4 (11 WKY and 11 SHR) vasopressin V1 receptor antagonist 1-(1-mercapto-4-methylcyclohexaneacetic acid)-8-arginine-vasopressin (MeCAAVP) was infused (1.52 micrograms/kg/min). In series 1 in WKY NLA elicited a long-lasting, significant increase in mean blood pressure (max 46 +/- 3 mmHg at 40 min). In SHR mean blood pressure raises were not significant (max 22 +/- 6 mmHg). In series 2, both in WKY and SHR, indomethacin elicited only transient, nonsignificant increases in mean blood pressure. In series 3, the mean blood pressure fall during the captopril infusion was more pronounced in SHR than in WKY (45 +/- 2 mmHg vs 13 +/- 2 mmHg respectively). In series 4 vasopressin V1 receptor blockade caused a nonsignificant fall in mean blood pressure, both in WKY and SHR.(ABSTRACT TRUNCATED AT 250 WORDS)
Analysis of Variance↗