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At least 793 records · Page 44Linked to original sources
PubMed1981

Noninvasive vascular laboratory diagnosis of deep venous thrombosis.

One hundred and seventeen consecutive patients with suspected deep venous thrombosis (DVT) were studied for a total of 233 limbs in a period of two years. Doppler signals were assessed at the femoral, popliteal, and posterior tibial veins. The pulse volume recorder was used to determine segmental venous capacitance and maximum venous outflow. The mean age was 55.2 years and the male to female ratio was 1:1. Of the 113 legs without suggestion of DVT studies as controls, three were found to have DVT by laboratory criteria and resulted in three cases of bilateral DVT. One hundred and ten limbs that were clinically unsuspected and 79 (66%) that were suspected were negative by the laboratory method. Of these, 106 unsuspected limbs and 42 suspected (35%) did not require venography and were not treated. Thirty-seven suspected legs (31%) and four unsuspected were proven to be negative not only by the laboratory criteria, but also by venography. Eighteen (15%) clinically suspected limbs and two (2 per cent) unsuspected limbs were positive both by venography and laboratory criteria. Eighteen (15%) suspected limbs and one unsuspected were positive by laboratory criteria and were treated without venographic confirmation. There was one false-positive and four false-negatives for an overall error of 4.2 per cent. From the true accuracy rate of 92 per cent, sensitivity of 83 per cent, and specificity of 98 per cent, the author concludes that this is a useful method in the diagnosis of DVT. Most of the false-negatives occurred in patients with recurrent DVT.

Adolescent↗
PubMed1993

Cardiovascular and renal effects of atrial natriuretic factor.

Atrial natriuretic factor (ANF) reduces cardiac output and systemic arterial blood pressure. The reduction in systemic arterial blood pressure is not caused by dilation of arterial resistance vessels, since total peripheral vascular resistance often increases during infusion of ANF. The reduction in cardiac output with subsequent hypotension can be explained by a decrease in venous return. The decrease in venous return is not due to pooling of blood in the capacitance vessels, since ANF reduces venous compliance. Reduced venous return during infusion of ANF can be explained by a reduction in circulating blood volume and an increase in resistance to venous return. The reduction in circulating blood volume is due to increased urine output and to a shift of circulating fluid into the interstitial space. The increase in renal sodium and water excretion is mediated by an increase in glomerular filtration rate and reduced sodium and chloride reabsorption in the collecting ducts. ANF also inhibits the renin-angiotensin-aldosterone system. The plasma level of ANF may be a parameter for the severity of heart diseases with increased preload. In congestive heart failure and supraventricular tachycardia, the increase in plasma ANF concentration may augment sodium excretion, but anti-natriuretic factors, such as reduction in renal perfusion pressure, may override the natriuretic effect of ANF. Reduced sodium excretion during mechanical ventilation with positive end-expiratory pressure (PEEP) is partly due to a decrease in ANF secretion.

Animals↗
PubMed1996

Inhibition of a store-operated Ca2+ entry pathway in human endothelial cells by the isoquinoline derivative LOE 908.

1. The novel cation channel blocker, LOE 908, was tested for its effects on Ca2+ entry and membrane currents activated by depletion of intracellular Ca2+ stores in human endothelial cells. 2. LOE 908 inhibited store-operated Ca2+ entry induced by direct depletion of Ca2+ stores with 100 nM thapsigargin or 100 nM ionomycin with an EC50 of 2 microM and 4 microM, respectively. 3. LOE 908 did not affect thapsigargin- or ionomycin-induced Ca2+ release from intracellular stores up to concentrations of 3 microM. 4. LOE 908 reversibly suppressed thapsigargin- as well as ionomycin-induced whole-cell membrane currents. 5. The LOE 908-sensitive membrane conductance corresponded to a cation permeability of 5.5 and 6.9 fold selectivity for Ca2+ over K+ in the presence of thapsigargin and ionomycin, respectively. 6. Our results suggest that the isoquinoline, LOE 908 is a novel, potent inhibitor of the store-operated (capacitive) Ca2+ entry pathway in endothelial cells.

Acetamides↗
PubMed1998

Baseline biophysical parameters in subjects with sensitive skin.

Sensitive skin has been described as a skin type showing higher reactivity than normal skin and developing exaggerated reactions when exposed to external factors. The stinging test, performed by applying lactic acid to the nasolabial fold and evaluating the intensity of subjective symptoms, is widely accepted as a marker of sensitivity and employed for the selection of subjects experiencing invisible cutaneous irritation. However, this test is based on self-perceived assessment and lacks objectivity. In order to contribute to the finding of objective descriptors, we assessed baseline biophysical parameters in subjects with sensitive skin by means of transepidermal water loss (TEWL), capacitance, pH, sebum and skin colour measurements, and compared the data with those obtained in normal subjects, also correlating the results with those of clinical assessments and functional tests. Subjects with sensitive skin showed a trend towards higher scores at all assessment times both for the stinging and the washing test. The skin of sensitive subjects was described as less supple, less hydrated and more erythematous and telangiectatic with respect to the skin of normal subjects. A trend towards an increase in TEWL, pH and colorimetric a* values, and a decrease in capacitance, sebum and colorimetric L* values on the face of subjects with sensitive skin was observable. However, significances were only present for capacitance and a* values. Thus, alterations of baseline capacitance values indicate the tendency to barrier impairment and support the view that skin hyperreactivity to water-soluble irritants is induced by a greater amount of irritants absorbed, whereas the increase in the erythema parameter shows that cutaneous vascular hyperreactivity in subjects with sensitive skin also corresponds to baseline vasodilation.

Adult↗
PubMed1981

Haemodynamic effects of nitroglycerin in comparison with preload and sodium nitroprusside on patients after coronary bypass surgery.

To differentiate between the haemodynamic effects of intravenous nitroglycerin (NTG) and preload, left ventricular function curves were constructed for 10 patients with and without a steady NTG-infusion at left ventricular filling pressure (LVFP) levels of between 9 and 17 mmHg eight hours after coronary bypass grafting. The haemodynamic effects of NTG were compared with those caused by sodium nitroprusside (NP) at identical filling pressures. Although NTG as such decreased cardiac index (CI) (p less than 0.05), when systemic vasodilation was induced, CI was 18% greater with than without NTG at constant filling pressures (p less than 0.02). At identical LVFP, mean arterial pressure remained unchanged by NTG, whereas systemic vascular resistance was reduced by 16%. NTG augmented the left ventricular stroke work index (LVSWI) only in patients whose initial LVSWI was below 30 gm-m/m2 (a 20% increase, p less than 0.05). Although NTG relaxes the capacitance vessels more than the resistance vessels, its haemodynamic effects are far superior to the changes that can be induced by preload alteration alone. NTG enhances myocardial performance, especially if LVFP is kept balanced with the reduction of afterload. The increase in left ventricular pumping performance produced by NTG was 45% of the increase produced by NP at identical filling pressures. The results, however, indicate that NTG may affect the myocardial oxygen supply/demand ratio more favourably than NP.

Adult↗
PubMed1976

[Role of reactions of large-capacity blood vessels in the pathogenesis of experimental cardiogenic shock].

Reaction of the capacitance vessels of the abdominal cavity and the pelvis was studied in dogs with the cardiotoxic myocardial necrosis complicated by the cardiogenic shock. The deposit of a significant volume of the circulating blood in the venous part of the vascular reservoir of the abdominal cavity and the pelvis was observed in the course of the first minutes of acute myocardial necrosis. A substantial role of reduction of the venous return to the heart in the pathogenesis of the hemodynamic disturbances accompanying the development of the cardiogenic shock is emphasized.

Abdomen↗
PubMed1975

[The neurogenic component of the tone of capacitance vessels in regional arterial hypotension].

It was shown in experiments on rats that lowering of the volume stiffness of the capacitance vessels in the area of the chronic regional arterial hypotension occurred only after their denervation. Experiments on the innervated hind limb showed that the volume stiffness of the capacitance vessels in the area of hypotension failed to differ from the corresponsing indices in control rats.

Animals↗
PubMed1990

Heart failure: mechanisms of cardiac and vascular dysfunction and the rationale for pharmacologic intervention.

Congestive heart failure is a complex clinical syndrome that has its basis in an abnormality of myocardial cell function resulting in impaired ventricular performance, exercise intolerance, and ventricular arrhythmias. The functional defect in myocardial performance may be related to alterations in receptor function, in regulatory proteins, or in biochemical mechanisms. Remodeling of the left ventricle has been observed to play an important role in the natural course of heart failure. The complex interplay between cellular elongation, reactive hypertrophy, and the influence of the change from ellipsoid to spheroidal shape of the left ventricle after acute myocardial infarction are just beginning to be understood. Prevention of this remodeling effect by pharmacologic intervention is being widely explored, although the mechanisms are poorly defined. Impedance to left ventricular ejection is also an important determinant of cardiac performance in heart failure. Constriction of arteriolar resistance vessels and reduction in compliance of arterial conductance vessels is a common manifestation of heart failure and may be under the influence of neural, hormonal, endothelial, and local regulatory factors. Increased tone of venous capacitance vessels contributes to a shift of blood centrally and to an increase in ventricular preload. Vasodilator drugs by relaxing the arterial, arteriolar, and venous vasculature result in a reduction in impedance and left ventricular afterload and a decrease in cardiac filling pressure and preload. Structural changes of hypertrophy and remodeling apparently contribute to the changes in resistance, compliance, and capacitance in the vasculature. Treatment of heart failure is aimed at relieving symptoms and prolonging life. Interventions to improve left ventricular function are critical to symptom relief. Vasodilators have been most effective for this purpose, and new positive inotropic drugs are being tested for efficacy. Long-term benefit may require interference with the myocardial and peripheral vascular remodeling processes that lead to progressive depression of ventricular performance. New insights into the cellular and subcellular mechanisms of this progression are critical to the development of innovative therapeutic strategies.

Cardiovascular System↗
PubMed1983

Calcium, vascular smooth muscle, and calcium entry blockers in hypertension.

Increases in vascular tone induced by an increase in cytosol calcium concentration may be important in the development of hypertension, myocardial ischemia, and other cardiovascular disorders. A heterogeneous group of compounds known as calcium entry blockers inhibit smooth muscle contraction induced by physiologic and pharmacologic stimuli by blocking transmembrane transport of calcium through membrane channels. These drugs may reduce blood pressure through effects on the heart, the venous capacitance vessels, the arterial resistance vessels, and the renin-angiotensin system. Although their efficacy in antihypertensive therapy may eventually prove to be nonspecific, their ability to interfere with a basic cellular mechanism for vasoconstriction makes these drugs attractive as potential specific treatment for the abnormal vasomotion in patients with hypertension.

Blood Pressure↗
PubMed2005

A new biomechanical perfusion system for ex vivo study of small biological intact vessels.

The vascular endothelium transduces physical stimuli within the circulation into physiological responses, which influence vascular remodelling and tissue homeostasis. Therefore, a new computerized biomechanical ex vivo perfusion system was developed, in which small intact vessels can be perfused under well-defined biomechanical forces. The system enables monitoring and regulation of vessel lumen diameter, shear stress, mean pressure, variable pulsatile pressure and flow profile, and diastolic reversal flow. Vessel lumen measuring technique is based on detection of the amount of flourescein over a vessel segment. A combination of flow resistances, on/off switches, and capacitances creates a wide range of pulsatile pressures and flow profiles. Accuracy of the diameter measurement was evaluated. The diameters of umbilical arteries were measured and compared with direct ultrasonographic measurement of the vessel diameter. As part of the validation the pulsatile pressure waveform was altered, e.g., in terms of pulse pressure, frequency, diastolic shape, and diastolic reversal flow. In a series of simulation experiments, the hemodynamic homeostasis functions of the system were successfully challenged by generating a wide range of vascular diameters in artificial and intact human vessels. We conclude that the system presented may serve as a methodological and technical platform when performing advanced hemodynamic stimulation protocols.

Animals↗
PubMed1988

Hemodynamic, renal, and neurohumoral effects of a selective oral DA1 receptor agonist (fenoldopam) in patients with congestive heart failure.

Fenoldopam mesylate (SK&F 82526-J) is a novel benzazepine derivative. It has selective agonist activity at post-junctional (DA1) vascular dopaminergic receptors, which normally subserve renal artery vasodilation. Previous studies in normal subjects and in patients with hypertension indicate that fenoldopam increases renal blood flow and promotes a sodium diuresis. Drug efficacy was clinically evaluated in eight patients with chronic congestive heart failure (CHF) after a single oral dose of 100 mg of fenoldopam and following 3 days of therapy (100 mg four times daily). Stroke volume index acutely increased from 26 +/- 7 (mean +/- SD) to 30 +/- 4 ml/beat/m2 (p less than 0.05) and left ventricular filling pressure decreased from 26 +/- 13 to 23 +/- 11 mm Hg (p less than 0.05). Systemic vascular resistance decreased from 1513 +/- 159 to 1128 +/- 319 (p less than 0.05). Hemodynamic changes were seen as early as 30 minutes following fenoldopam and returned to control levels by 4 hours. Forearm blood flow, hepatic blood flow, and venous capacitance did not significantly change acutely, but renal blood flow index was significantly reduced (34 +/- 4 to 30 +/- 3 min-1 X 1000, p less than 0.01). Plasma norepinephrine, plasma renin activity, plasma arginine vasopressin, and plasma aldosterone did not significantly change acutely. After 3 days of treatment, 100 mg of fenoldopam again reduced the renal blood flow index (35 +/- 7 to 26 +/- 7 min-1 X 1000, p less than 0.01) and tended to increase plasma renin activity (11.7 +/- 8 to 21.2 +/- 19.4 ng/ml/hr, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1997

An analysis of the effects of nitroglycerin on forearm circumference, with simultaneous recordings of arterial and venous diameters and blood pressure.

The aim of this study is to define the effect of sublingually administered nitroglycerin (NTG) on the diameters of the forearm arteries and veins as well as to define the relationship between these vascular changes and the forearm circumference in healthy volunteers. For this purpose, we employed a noninvasive method permitting the simultaneous quantitative recording of vascular diameters, forearm circumference and blood pressure using a miniature load cell, linear differential transformers and mercury-in-rubber strain gauge. Sublingually administered NTG (0.3 mg) increased the radial arterial diameter and the forearm circumference, whereas the cephalic vein capacitance was decreased; consequently, the cephalic vein acts to moderate the increase in forearm circumference. The results clearly indicate that nitroglycerin dilates forearm arteries but not forearm veins in the normal state.

Adult↗
PubMed1990

[Application of ultrasono-micrometric technic to study vasomotility].

An experimental model of simultaneous recording of pressure and flow (instantaneous and mean values) and of the vascular diameter (by ultrasonomicrometry) at the entry of a clearly limited territory of the systemic circulation has been developed in the animal together with a programme of data aquisition and analysis. This programme allows quantification of the different viscoelastic properties of the vessel wall which characterise arterial flow in the arteries of distribution (capacitance vessels) and irrigation (resistance vessels). The model was applied to the study of the pharmacological effects of two antianginal agents, a nitrate derivative (ND) administered acutely by slow intravenous infusion at a dose of 25 micrograms/Kg/mn over 20 minutes (total dose: 500 micrograms/Kg) and a substitute sydronimous substance (SYD) administered in the same manner at a dose of 15 g/Kg/mn over 20 minutes (total dose: 300 micrograms/Kg). The hypotensive effects obtained were comparable and significant (p less than 0.001) in both cases. The ND led to a fall in mean blood pressure of 9.7 +/- 1.3% and SYD of 10.0 +/- 2.1%. However, SYD led to an increase in aortic blood flow (11.7 +/- 3.6%, p less than 0.01) whilst the ND had no significant effect on this parameter (+ 6.07 +/- 5.7%). As a result, there was a much greater decrease of peripheral resistances after administration of SYD (-22.8 +/- 3.1%) than with the ND (-12.7 +/- 4.2%). This difference was also observed when the input impedence of the vascular bed was studied (-31.2 +/- 6.9% after SYD and -12.0 +/- 2.5% after the ND).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗