Plasma concentrations of atrial natriuretic peptide, arginine vasopressin and hormones of the renin-angiotensin system in patients with end-stage renal disease

Plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), plasma renin activity (PRA) and aldosterone, were measured before and after 3 h of hemodialysis in 9 patients with end-stage renal disease on maintenance hemodialysis. Hormone concentrations were also determined in the same patients on a separate occasion after 1 h of ultrafiltration (UF). Plasma concentrations of ANP were significantly higher in the patients with ESRD than in a normal reference population and declined after both 1 h and 3 h of hemodialysis. Plasma concentrations of ANP failed to exhibit a significant decline after 1 h of UF. Plasma AVP concentrations were not significantly different after either hemodialysis or UF, while plasma aldosterone concentrations fell with hemodialysis. The decline in plasma aldosterone concentrations paralleled the decrease in dialysis-induced fall in serum potassium concentrations. There was no correlation between the blood pressures, heart rate, interdialytic weight gain and estimated fluid overload and any of the hormones measured except for the plasma renin activity (PRA) which correlated significantly with the systolic blood pressure. The data suggest that ANP may not be a major factor in blood pressure regulation in normotensive patients with ESRD and its elevation in patients with ESRD is most likely due to fluid overload and atrial distention as well as a possible reduction in its metabolic clearance in renal insufficiency. The fall in plasma ANP following hemodialysis is not due to its removal by dialysis but is most likely due to a reduction in ANP production caused by dialysis-induced correction of hypervolemia.     

Heterogeneity of left ventricular segmental wall thickening and excursion in 2-dimensional echocardiograms of normal human subjects

Regional abnormalities of left ventricular (LV) wall thickening and excursion have been demonstrated by 2-dimensional (2-D) echocardiography. However, the variability of normal segmental contraction has not previously been defined. We performed 2-D echocardiography in 12 normal men aged 19 to 27 years. We obtained short-axis images at the level of the mitral valve, chordae tendineae, papillary muscles, and apex at end-diastole and end-systole. A computer-based system divided each short-axis image into 12 cavity and wall segments, and analyzed percent systolic wall thickening along each radius and percent area change of each cavity segment. Overall variability of contraction as well as the contributions of several sources of variability were determined. The overall range of cavity segment area change was 0 to 100% and of segmental wall thickening was 0 to 150% in these normal subjects. Average contraction was similar at different ventricular levels. Significant differences were found between adjacent segments at each level as well as between subjects. Intrathoracic cardiac rotation and motion were minimal; correction for these movements did not significantly alter the variability of contraction as calculated from 2-D echocardiograms. Temporal asynergy of contraction did contribute to variability; correction resulted in a significant alteration in mean segmental area change (from 59 ± 20% [standard deviation] uncorrected to 66 ± 16% corrected, p < 0.001) and in mean segmental wall thickening (58 ± 29% uncorrected to 71 ± 34% corrected, p < 0.01). Substantial interexamination variability also occurred with an average difference in cavity segment area change of 20% per segment and in segmental wall thickening of 29% per segment between 2 analyses by the same observer. Thus, considerable intersegmental and intersubject variability of LV contraction occurs in normal subjects as exhibited on 2-D echocardiograms, exaggerated by technical difficulties in analyzing and reproducing the echocardiographic tracings. Significant differences in segmental wall thickening and endocardial excursion may occur in adjacent segments in normal subjects, and therefore such differences alone may not indicate cardiac disease.     

Plasma insulin-like growth factors and bone formation in uremic hyperparathyroidism

Bone formation in uremia is considered to be regulated in part by parathyroid hormone (PTH). However, while low levels of immunoreactive PTH are usually associated with low rates of bone formation in uremia, elevated PTH levels do not always correlate with increased bone formation. In an attempt to identify other factors that may regulate bone formation in uremic patients, we measured plasma immunoreactive insulin-like growth factors (IGF-I and IGF-II) in 15 patients who did not have aluminum-associated reductions in bone formation. Plasma levels of IGF-I but not PTH, were significantly higher in patients with high rates of bone formation when compared to patients with low or normal bone formation (P less than 0.02). While the bone formation rate at the tissue level correlated significantly with plasma PTH (r = 0.53, P less than 0.05) and IGF-I (r = 0.67, P less than 0.01), only for plasma IGF-I were there significant correlations with bone apposition (r = 0.57, P less than 0.05) and bone formation rate at the BMU level (r = 0.62, P less than 0.02), parameters which reflect mineralization activity at the cellular level. Among the static histologic parameters, osteoblastic osteoid correlated only with plasma PTH (r = 0.76, P less than 0.001), while osteoclast number correlated with both PTH (r = 0.56, P less than 0.05) and IGF-I (r = 0.67, P less than 0.01). There were no correlations between IGF-II levels and bone histology. From these data we suggest that IGF-I may promote bone formation in uremic patients with hyperparathyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Circadian blood pressure variation after acute stroke.

We aimed to characterise the patterns of circadian blood pressure (BP) variation after acute stroke and determine whether any relationship exists between these patterns and stroke outcome. BP was recorded manually every 4 h for 48 h following acute stroke. Patients were classified according to the percentage fall in mean systolic BP (SBP) at night compared to during the day as: dippers (fall > or = 10-<20%); extreme dippers (> or = 20%); non-dippers (> or = 0-<10%); and reverse dippers (<0%, that is, a rise in mean nocturnal SBP compared to mean daytime SBP). One hundred and seventy-three stroke patients were included in the study (83 men, 90 women; mean age 74.3 years). Four patients (2.3%) were extreme dippers, 25 (14.5%) dippers, 80 (46.2%) non-dippers and 64 (36.9%) reverse dippers. There was a non-significant trend in the proportion of patients who were dead or dependent at 3 months in the extreme dipper (p=0.59) and reverse dipper (p=0.35) groups. Non-dipping and reverse-dipping were relatively common patterns of circadian BP variation seen in acute stroke patients. These patterns were not clearly associated with outcome.     

Decreased levels of soluble amyloid β-protein precursor are associated with Alzheimer's disease in concordant and discordant monozygous twin pairs

We conducted immunochemical measurements of soluble amyloid β-protein precursor (βPP) in cerebrospinal fluid (CSF) from three monozygous twin pairs. Two of the twin pairs are discordant for Alzheimer's disease and one pair showed concordance for Alzheimer's disease, which was confirmed neuropathologically. All affected individuals displayed substantially lower levels of soluble βPP in CSF compared with the unaffected individuals. There were no differences in total protein levels in CSF samples from the affected twins compared with those of the unaffected twins. These studies suggest that decreased soluble βPP in CSF may reflect neuropathological processes in Alzheimer's disease involving βPP.     

Risk of relapse among non-lepromatous patients released from treatment after dapsone monotherapy.

Information on 14,625 non-lepromatous patients released from treatment after dapsone monotherapy and followed up to a maximum of 15 years at the ILEP project. Dharmapuri, India, was analysed to study the pattern of relapses. The overall relapse rate was 5/1000 person years. Males had a higher relapse rate than females. The risk of relapse increased with age, number of lesions and duration of treatment. The risk for relapse remained constant over several years after release from treatment. Even though the absolute risk for relapse after MDT may be different, the pattern of relapses and the factors affecting it may be similar to what has been shown in this study.