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Biomedical subjects

J Polonia

Publications and source records attributed to J Polonia.

8 recordsLinked to original sources
PubMed1995

Accuracy of twenty-four-hour ambulatory blood pressure monitoring (night-day values) for the diagnosis of secondary hypertension.

OBJECTIVES: To determine the accuracy of 24-h ambulatory blood pressure monitoring, using the relationship between night-time and daytime values, in diagnosing secondary hypertension. PATIENTS AND METHODS: A prospective study was performed in a referred population of 402 hypertensive patients (clinic systolic/diastolic blood pressure > 140/90 mmHg). The ambulatory monitoring data included 24-h mean, awake (daytime) and sleeping (night-time) values. Secondary hypertension was diagnosed by standard procedures. To describe the accuracy of ambulatory blood pressure monitoring, receiver-operator characteristic curves were constructed, using sensitivity and specificity values for deciles of the distribution of overnight blood pressure falls (absolute and percentage). Measurements included the fall in nocturnal blood pressure, sensitivity (the percentage of those with secondary hypertension who were classified as non-dippers), specificity (the percentage of non-secondary hypertensives who were classified as dippers) and predictive values of ambulatory blood pressure monitoring. RESULTS: On average, overnight systolic/diastolic blood pressure fell in primary hypertensives (n = 290) by 20/18 mmHg (13%/19%), in white-coat hypertensives (n = 65, daytime ambulatory blood pressure <135/87 mmHg) by 17/15 mmHg (13%/19%) and in patients with secondary hypertension (n = 47, renal/renovascular and endocrine forms) by 13/11 mmHg (9%/12%). From receiver-operator characteristic curves, the nocturnal blood pressure fall of 15 mmHg showed the highest accuracy, with a sensitivity/specificity of 61%/69% (systolic) and 75%/62% (diastolic) whereas 10% (systolic) and 15% (diastolic) nocturnal falls had a sensitivity/specificity of 62%/74% (systolic) and 62%/70% (diastolic). The ambulatory blood pressure data had a high (>93%) negative predictive value for secondary hypertension. CONCLUSIONS: Secondary hypertension is associated with a blunted nocturnal fall in blood pressure. Ambulatory blood pressure monitoring data are not critically important for the diagnosis and screening of secondary hypertension but may be helpful in excluding it.

Adolescent↗
PubMed1993

Atrial natriuretic factor and changes in the aldosterone response to angiotensin II in sodium depleted dogs.

The effects of physiological shifts in plasma atrial natriuretic factor (ANF) concentrations on angiotensin II/aldosterone relationships during changes in sodium status were assessed in 6 conscious beagle dogs. Incremental infusions of angiotensin II (3, 9 and 27ng/kg/min) were administered on three occasions. The animals were studied in sodium replete and deplete states and on a third occasion, again while sodium deplete, with a background constant low-dose infusion of ANF (1.5pmol/kg/min) sufficient to enhance the low endogenous plasma ANF values observed in sodium depletion to match those observed in the sodium replete state. Sodium depletion caused a leftward shift and steepened the slope of the relationship between achieved arterial angiotensin II concentrations and the plasma aldosterone response. This effect was significantly attenuated (approximately 50%) by the low dose ANF infusions which tended to flatten the slope of the angiotensin II/aldosterone curve (ns) and shifted it significantly to the right (p < 0.05). These data suggest subtle shifts in endogenous levels of plasma ANF, accompanying changes in sodium status, are a major contributor to the associated alterations in angiotensin II/aldosterone relationships. Low dose ANF also significantly reduced the effect of angiotensin II on arterial pressures but did not alter natriuresis.

Aldosterone↗
PubMed1990

Changes in plasma atrial natriuretic factor during sequential fluid removal and biochemical correction in end-stage chronic renal failure patients.

Plasma immunoreactive atrial natriuretic factor (ANF) levels, their chromatographic profiles (high-performance liquid chromatography; HPLC) and changes during sequential ultrafiltration (UF; 1 litre/h) and biochemical correction without fluid removal (BC; 3 h) were studied in 8 end-stage chronic renal failure patients on intermittent haemodialysis (greater than 1 year). Patients entered randomly the UF-BC or BC-UF protocols that were reversed after 1 week. HPLC showed a single peak of ANF immunoreactivity in plasma of end-stage chronic renal failure patients before dialysis sessions. ANF at the end of fluid removal fell by 31 +/- 2% (p less than 0.01) during UF-BC and by 30 +/- 2% (p less than 0.01) at the end of BC during BC-UF. In both sequences a further slight reduction in plasma ANF was observed during the second phase: it was 8.5 +/- 5% (n.s.) during BC of the BC-UF and 12.5 +/- 2% (p less than 0.05) during fluid removal of BC-UF. Plasma ANF was not significantly removed by the machinery. BC did not modify the microhaematocrit in the BC-UF sequence while the microhaematocrit was significantly increased by UF (13 +/- 1 and 14 +/- 1%, p less than 0.005 vs. basal, respectively), and decreased by BC in the UF-BC sequence (-5 +/- 2% vs. end UF, p less than 0.05). Serum creatinine and urea decreased significantly during BC in both protocols while they were unmodified during UF. No significant changes were seen in PRC during either protocol.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Natriuretic Factor↗
PubMed1988

Atrial natriuretic peptides and renin release.

The relationship between endogenous plasma concentrations of atrial natriuretic peptide and renin was examined in resting normal subjects and patients with cardiac impairment. To test the hypothesis that atrial natriuretic peptide inhibits renin secretion, intravenous infusions of atrial natriuretic peptide were administered to normal volunteers, patients with end-stage renal failure, and conscious dogs in both sodium-replete and sodium-depleted states. Plasma atrial natriuretic peptide and renin were inversely related in normal subjects (r = -0.52, n = 140, p less than 0.001), but a weak positive association between these two variables was observed in patients with cardiac impairment (r = 0.32, n = 60, p less than 0.02). Low doses of both 26- and 28-amino-acid human atrial natriuretic peptide (2 pmol/kg/minute for two hours) given to sodium-replete normal subjects halved plasma renin compared with time-matched placebo values (19 +/- 4 and 18 +/- 3 versus 36 +/- 8 microU/ml, p less than 0.001 for both). Incremental doses of synthetic atrial natriuretic peptide suppressed plasma renin below time-matched placebo values in both sodium-replete (maximal suppression 1.2 +/- 0.4 versus 8.6 +/- 1.4 microU/ml, p less than 0.001) and sodium-depleted (maximal suppression 18.9 +/- 4.9 versus 51 +/- 13 microU/ml, p less than 0.05) dogs. This effect was initially apparent at low doses of atrial natriuretic peptide (1 pmol/kg/minute), and renin suppression was maximal, in both states, with lesser doses of atrial natriuretic peptide than those at which maximal natriuresis was observed. Atrial natriuretic peptide administered to patients with end-stage renal failure (10 pmol/kg/minute for one hour) caused no change in plasma renin. These data confirm that atrial natriuretic peptide inhibits renin secretion in a dose-related manner and suggest that this action of the peptide is modified by both the baseline sodium status and renal function of the recipient.

Adult↗
PubMed1988

Contrasting plasma atrial natriuretic factor concentrations during comparable natriuresis with infusions of atrial natriuretic factor and saline in normal man.

1. To explore the role of atrial natriuretic factor (ANF) in the response to an acute saline load, we compared plasma hormone and urinary electrolyte interrelationships during administration of ANF and saline. Plasma concentrations of ANF, renin, angiotensin II and aldosterone, together with urine volume and electrolytes, were measured during infusions of placebo, ANF [alpha-human ANF (99-126)] and 0.9% (w/v) NaCl solution in normal subjects under standardized conditions of diet and posture. 2. Saline loading and ANF infusions initially induced similar natriuresis and suppression of renin-angiotensin-aldosterone system activity in association with markedly disparate values of plasma ANF. Plasma ANF levels rose to two- and eight-fold placebo values with saline and ANF, respectively (P less than 0.001). Conversely, in the period after infusion plasma ANF values were similar while natriuresis differed significantly. Peak natriuresis lagged behind peak plasma ANF values with both stimuli. 3. ANF, but not saline, enhanced urinary excretion of calcium and magnesium. Saline, but not ANF, caused increased kaliuresis. 4. The data suggest that ANF makes only a minor contribution to natriuresis induced by saline challenge, although full confirmation of this point requires quantification of end-organ responses to endogenous ANF in the face of changing arterial pressure and circulating volume.

Adult↗
PubMed1988

Plasma clearance and effects of alpha-hANP infused in patients with end-stage renal failure.

The effects and clearance of synthetic atrial natriuretic peptide (alpha-hANP) were investigated in eight patients with end-stage renal failure and six normal volunteers. ANP or vehicle was infused for 1 h at 10 pmol.kg-1.min-1 in random order on two separate occasions. During ANP infusions in end-stage renal patients, microhematocrit rose by 9.8 +/- 2% (P less than 0.005, n = 8), from base-line values of 0.24 +/- 0.02. Serum protein and albumin rose consistently. In contrast, during placebo infusions, no significant changes were seen. Blood pressure, heart rate, plasma renin concentration, serum creatinine, and electrolytes did not change significantly during either study phase. In end-stage renal failure patients, metabolic clearance rate of infused ANP was 1.04 +/- 0.095 l/min and its plasma half-life was 4 min 34 s. In normal volunteers, metabolic clearance rate was 2.6 l/min and its plasma half-life 3 min 30 s. The data suggest that ANP promotes contraction of plasma volume via a mechanism independent of renal function and also indicate that the kidney is not the only organ involved in the ANP metabolism.

Adult↗
PubMed1987

Correlates of plasma atrial natriuretic factor in health and hypertension.

Plasma concentrations of atrial natriuretic factor (ANF) were compared in normotensive subjects and subjects with untreated, uncomplicated essential hypertension (n = 21 pairs) matched for age, sex, and race. Plasma peptide values were slightly greater (45 +/- 3 vs 36 +/- 3 pg/ml; p less than 0.05) in the hypertensive group. On univariate analysis, age (r = 0.52, n = 47, p less than 0.001) and creatinine clearance (r = -0.30, n = 47, p less than 0.05) were significantly related to plasma ANF concentrations, but arterial pressure was not (r = 0.14, n = 47), in an extended group of normal subjects. In contrast, plasma ANF values were related to arterial pressure in both an extended group of subjects with untreated essential hypertension (r = 0.54, n = 38, p less than 0.001) and in our total heterogeneous pool of hypertensive patients (r = 0.46, n = 79, p less than 0.001), but weak positive associations with age and inverse relationships with creatinine clearance were not statistically significant in either hypertensive group. Similar weak inverse relationships between plasma ANF values and renin-angiotensin-aldosterone system activity were found in both normal and hypertensive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗