Studies of plasma volume using human serum albumin tagged with radioactive iodine

Assessing the Validity of Normalizing Aflatoxin B1-Lysine Albumin Adduct Biomarker Measurements to Total Serum Albumin Concentration across Multiple Human Population Studies

The assessment of aflatoxin B₁ (AFB₁) exposure using isotope-dilution liquid chromatography-mass spectrometry (LCMS) of AFB₁-lysine adducts in human serum albumin (HSA) has proven to be a highly productive strategy for the biomonitoring of AFB₁ exposure. To compare samples across different individuals and settings, the conventional practice has involved the normalization of raw AFB₁-lysine adduct concentrations (e.g., pg/mL serum or plasma) to the total circulating HSA concentration (e.g., pg/mg HSA). It is hypothesized that this practice corrects for technical error, between-person variance in HSA synthesis or AFB₁ metabolism, and other factors. However, the validity of this hypothesis has been largely unexamined by empirical analysis. The objective of this work was to test the concept that HSA normalization of AFB₁-lysine adduct concentrations effectively adjusts for biological and technical variance and improves AFB₁ internal dose estimates. Using data from AFB₁-lysine and HSA measurements in 763 subjects, in combination with regression and Monte Carlo simulation techniques, we found that HSA accounts for essentially none of the between-person variance in HSA-normalized (R² = 0.04) or raw AFB₁-lysine measurements (R² = 0.0001), and that HSA normalization of AFB₁-lysine levels with empirical HSA values does not reduce measurement error any better than does the use of simulated data (n = 20,000). These findings were robust across diverse populations (Guatemala, China, Chile), AFB₁ exposures (10⁵ range), HSA assays (dye-binding and immunoassay), and disease states (healthy, gallstones, and gallbladder cancer). HSA normalization results in arithmetic transformation with the addition of technical error from the measurement of HSA. Combined with the added analysis time, cost, and sample consumption, these results suggest that it may be prudent to abandon the practice of normalizing adducts to HSA concentration when measuring any HSA adducts—not only AFB₁-lys adducts—when using LCMS in serum/plasma.

Plasma volume, cell volume, total blood volume and F factor in the tree shrew

In this study, the physiological values of volumes of plasma, cells, total blood and the F blood factors were identified in 24 adult tree shrews (Tupaia belangeri; 12 male and 12 female; average BW of 123.9±19.19 g). The two-compartment model method of Evans Blue dye was used to obtain the plasma volume and the venous hematocrit was measured by microhematocrit method. To establish the relationship between body weight (BW) and blood volume of tree shrews, We performed linear fitting for these two datasets. Results were analyzed according to gender and weight (<120g vs.>120g). Statistical significance was assessed using the unpaired student t test and one-way ANOVA. The average volumes per 100g body weight of plasma, red blood cell (RBC) and total blood were 5.42±0.543, 3.24±0.445, and 8.66±0.680ml respectively. The mean body hematocrit, cardiac hematocrit, jugular vein hematocrit, femoral vein hematocrit, and tail vein hematocrit was 37.43±4.096, 39.72±3.219, 43.04±4.717, 40.84±3.041, and 38.71±3.442% respectively. The F cardiac was 0.94±0.072, F jugular vein 0.88±0.118, F femoral vein 0.92±0.111, and the F tail vein 0.97±0.117. Blood volume (ml) was 85.89103×BW (kg). This is the first study to provide the parameters of plasma volume, cell volume, total blood volume and F factor and a baseline for future research on blood physiology of tree shrews.

Modeling the Evans Blue Dilution Method for the Measurement of Plasma Volume in Small Animals: A New Optimized Method

The measurement of plasma volume (V_p) in humans and animals is frequently performed by the Evans blue dye dilution method. However, after injection of Evans blue into the circulation, no steady state is observed because of delayed mixing and progressive leakage of dye out of vascular space. Various methods of calculation have been proposed, either with a single blood sampling 5-10 min after dye injection (Single point method), or with extrapolation at time zero of a logarithmic decay (Log linear method). We propose a method based on a two-compartment hypothesis taking into account the initial mixing and the leakage phase in the time course of dye concentration. Nineteen Sprague-Dawley rats were studied in various conditions and blood sampling was performed before and 2, 4 and 6 min after injection of 200 μg Evans blue. A mathematical model was designed to describe the two-compartment hypothesis and allowed the calculation of V_p and K_out (rate of disappearance of dye from vascular space). A Bland and Altman representation evidenced an overestimation of V_p with previous methods and the great dispersion of results with the single point method, especially when using the 6 min point. Calculation of K_out revealed more accurate with the model than the Log linear method, especially when the mixing rate is slow. We suggest using the two-compartment model to measure V_p with Evans blue technique in rats. This method also allows precise evaluation of the rate of dye leakage, which could be a good marker of vascular permeability to albumin.

Measurement of Blood Loss in Cardiac Surgery: Still Too Much

BACKGROUND

Cardiac surgery is associated with a significant decrease in hematocrit. It is unclear whether that occurs from hemodilution, loss of red cells, or both. Hematocrit is a major determinant of transfusion decisions although transfusion is associated with increased morbidity and mortality. Physicians must determine whether this anemia is the result of hemodilution or red blood cell loss as the former would be treated with packed red blood cell transfusions and the latter by diuresis. We hypothesize that the decrease in hematocrit observed in cardiac surgery is due to hemodilution.

METHODS

Blood volume (BV), plasma volume (PV), and red blood cell volume (RBCV) were measured in 54 patients undergoing coronary artery bypass graft surgery, valve surgery, or coronary artery bypass graft/valve surgery. Measurements were made preoperatively, immediately postoperatively, and 2 hours after surgery utilizing a dilution tracer method and hematocrit measurements.

RESULTS

Preoperative average BV was 6,094 mL (SD 1,904 mL), RBCV was 2,024 mL (SD 720 mL), and PV was 4,070 mL (SD 1,339 mL). Postoperative average BV was 4,834 mL (SD 1,432 mL), RBCV 1,226 mL (SD 527 mL), and PV 3,607 mL (SD 993 mL). Blood volume decreased 18% (p < 0.0001), RBCV decreased 38% (p < 0.001), and PV decreased 8% (p < 0.012). There were no significant changes between postoperative values and those 2 hours later in the cardiac surgery intensive care unit.

CONCLUSIONS

Decreases in hematocrit observed in cardiac surgery patients are due to significant red blood cell losses and not to hemodilution. Red blood cell losses averaged 38%. Plasma volume also decreased.

Piperine activates human pregnane X receptor to induce the expression of cytochrome P450 3A4 and multidrug resistance protein 1

Activation of the pregnane X receptor (PXR) and subsequently its target genes, including those encoding drug transporters and metabolizing enzymes, while playing substantial roles in xenobiotic detoxification, might cause undesired drug-drug interactions. Recently, an increased awareness has been given to dietary components for potential induction of diet-drug interactions through activation of PXR. Here, we studied, whether piperine (PIP), a major component extracted from the widely-used daily spice black pepper, could induce PXR-mediated expression of cytochrome P450 3A4 (CYP3A4) and multidrug resistance protein 1 (MDR1). Our results showed that PIP activated human PXR (hPXR)-mediated CYP3A4 and MDR1 expression in human hepatocytes, intestine cells, and a mouse model; PIP activated hPXR by recruiting its coactivator SRC-1 in both cellular and cell-free systems; PIP bound to the hPXR ligand binding domain in a competitive ligand binding assay in vitro. The dichotomous effects of PIP on induction of CYP3A4 and MDR1 expression observed here and inhibition of their activity reported elsewhere challenges the potential use of PIP as a bioavailability enhancer and suggests that caution should be taken in PIP consumption during drug treatment in patients, particularly those who favor daily pepper spice or rely on certain pepper remedies.

Protective effects of dietary potassium chloride on hemodynamics of Dahl salt-sensitive rats in response to chronic administration of sodium chloride

BACKGROUND

Dietary potassium supplementation decreases blood pressure and prevents strokes in humans, and prevents strokes and renal damage in Dahl salt-sensitive (DSS) rats.

OBJECTIVE

To study the effects of various concentrations of dietary potassium chloride (KCl) on the hemodynamics of Dahl salt-resistant (DSR) and DSS rats receiving a 1% sodium chloride (NaCl) diet for 8 months, to determine whether there is an optimal dietary concentration of KCl that minimizes increases in blood pressure and causes least impairment of blood flow in the brain and kidneys.

METHODS AND RESULTS

We found a biphasic effect on hemodynamic parameters as a function of dietary KCl in DSS rats of the Rapp strain fed 1% NaCl with increasing dietary KCl (0.7, 2.6, 4 and 8%). After 8 months receiving a diet containing 1% NaCl and 0.7% KCl, DSS rats had mean arterial pressures (MAP), plasma volumes, cardiac outputs and renal and cerebral vascular resistances that were significantly increased compared with those of DSR rats receiving the same diet. With a 2.6% KCl diet, all these parameters were significantly reduced compared with those in DSS rats fed the 0.7% KCl diet and were similar to those in DSR rats fed 2.6% KCl. Total peripheral resistance in DSR and DSS rats was similar on all diets. When KCl was increased to 4 and 8%, MAP, plasma volume, cardiac output and renal vascular resistance progressively increased in DSR and DSS rats, without changing total peripheral resistance. These changes paralleled increases in plasma aldosterone, which resulted from adrenocortical stimulation by the increasing dietary KCl; however, cerebral vascular resistance of DSR and DSS rats decreased significantly with a 4% KCl diet, despite increased aldosterone and sodium retention. Only DSS rats fed a 2.6% KCl diet had hemodynamics similar to those of DSR control rats fed the same diet, and hyperaldosteronism, sodium retention and increased plasma volume did not occur.

CONCLUSION

'Optimal' dietary KCl (2.6%) prevents hypertension and preserves cerebral and renal hemodynamics in DSS rats fed a diet containing 1% NaCl for 8 months, which causes hypertension when dietary KCl is limited or excessive.

Multivariate analysis of the prognostic determinants of the depressor response to exercise therapy in patients with essential hypertension

This study investigated the contribution of hemodynamic and humoral factors to the variation in the depressor responses to exercise therapy and the significance of the baseline values of these factors in predicting the depressor response of essential hypertensives to mild exercise therapy. Patients with mild to moderate essential hypertension (n=122, F/M: 97/25) performed a bicycle ergometer exercise at a workload equivalent to the lactate threshold for 10 weeks. In all of the patients, systolic and diastolic blood pressures (BP) significantly decreased after 1 week of exercise, continued to decrease until 4 weeks, and were stable from 4 weeks to 10 weeks. Changes in the plasma volume and humoral factors during the study did not differ significantly between responders and non-responders. A multiple logistic regression analysis showed that higher baseline mean BP (MBP) was significantly associated with a poor depressor response (odds ratio 1.84, p=0.002). A variance component analysis indicated that baseline MBP accounted for only 11.2% of the total variance of the depressor response. In conclusion, these summarized results showed that variations in the depressor response to mild exercise therapy were partly determined by baseline MBP, but not by humoral factors, suggesting the possible involvement of other factors, including genetic factors.

Association of angiotensin-converting-enzyme gene polymorphism with the depressor response to mild exercise therapy in patients with mild to moderate essential hypertension

We studied the association of angiotensin I-converting enzyme (ACE) gene polymorphism with the depressor response to exercise therapy in 64 Japanese subjects with mild to moderate essential hypertension. Each subject performed 10 weeks of mild (lactate threshold intensity: approximately 50% maximum oxygen consumption) exercise therapy on a bicycle ergometer. Systolic blood pressure (SPB), diastolic blood pressure (DPB), and mean arterial pressure (MAP) were significantly decreased by exercise therapy in subjects with the ACE-II and ID genotypes but not in DD subjects. The time-by-genotype interaction effects were significant for DBP and MAP. According to a multiple logistic regression analysis, the age- and baseline plasma renin activity-adjusted relative risk (odds ratio) for the lack of a depressor response conferred by the D allele (assuming an additive effect) was 2.72 [95% confidence interval (CI), 1.07-6.91; p = 0.034]; for DD genotypes, as compared with the DI and II genotypes (assuming that the D allele is recessive), it was 11.7 (95% CI, 2.25-60.6; p = 0.003). ACE gene I/D polymorphism is associated with the depressor response of essential hypertensives to mild exercise therapy, which suggests that genetic features may underlie, at least in part, the heterogeneity of the depressor response in essential hypertensives to mild exercise therapy.

Brain extraction of 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]pyridinium ion (HPP+), a neurotoxic metabolite of haloperidol: studies using [3H]HPP+

Tritium-labeled 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]pyridinium ion (HPP+) was synthesized enzymatically from [3H]haloperidol using rat liver microsomal preparations, and using prepared [3H]HPP+, the passage of HPP+ into the brain was investigated. Consequently, HPP+ showed a moderate brain uptake index, indicating that it is able to permeate the blood-brain barrier. Furthermore, HPP+ was detected in murine brains after being intravenously injected. These results suggested that HPP+, produced mainly in the liver, is taken up into the brain and induces damage to brain dopaminergic neurons.

Systemic and renal response to salt loading in endothelin-1 knockout mice

Endothelin-1 (ET-1) knockout mice demonstrate elevated blood pressure, which may be associated with disturbance in central cardiorespiratory regulation. In this study we examined responses to salt loading in ET-1 knockout mice to investigate whether ET-1 is involved in the pathophysiology of salt-sensitive hypertension. Male Edn1+/- heterozygous mice and their wild-type littermates were fed either a high NaCl (8%) or a normal (0.2%) diet for 4 weeks. Systemic blood pressure and tissue ET-1 levels were measured as well as several parameters relating to sodium handling and volume homeostasis. On normal diet, renal ET-1 levels of Edn1+/- mice were about 50% of those of wild-type mice. A high-salt diet caused a significant decrease in renal ET-1 levels by about 50% in both groups. Urine volume, urinary sodium excretion, and FENa in mice on the 8% NaCl diet were significantly higher than those in mice on the 0.2% NaCl diet, whereas there were no differences in circulating plasma volume, serum electrocytes, and creatinine clearance. These responses were similar in Edn1+/- and wild-type mice. Although systemic blood pressure was significantly higher in Edn1+/- mice than in the wild-type, the effect of salt loading on blood pressure was not significant in either Edn1+/- or wild-type mice. We conclude that changes in ET-1 production within a physiologic range do not affect salt sensitivity, although renal ET-1 content is decreased by salt loading.

Crossover comparison between the depressor effects of low and high work-rate exercise in mild hypertension

1. The relationship between work-rate and the antihypertensive effect of exercise in hypertensives, and the mechanism of that effect, were investigated by a crossover clinical trial. 2. Ten mild hypertensives were randomly divided into two groups. One group performed low work-rate exercise (LWE) on a cycle ergometer for 10 weeks (blood lactate threshold; approximately 50% of maximum oxygen consumption [Vo2max]). After a 10 week interval without exercise training, these subjects were then switched to a high work-rate exercise (HWE) regimen (4 mmol/L of blood lactate; approximately 75% of Vo2max) for another 10 weeks. In the other group, the order of exercise training was reversed. Since two patients withdrew from the protocol during HWE periods, statistical analysis was performed on the data from the remaining eight patients. There were no order effects observed in any of the data from the two groups. 3. During both LWE and HWE, resting blood pressure (BP) fell significantly after the initiation of exercise therapy (P < 0.05). Furthermore, the overall effects of 10 weeks of LWE and HWE on BP were not significantly different. 4. The work-rate at the lactate threshold, which reflects physical fitness, had increased significantly by 16 W (P < 0.01) after the LWE period and by 11 W (P < 0.01) after the HWE. 5. During the LWE period, changes in haemodynamic and humoral variables were not significant, except for a reduction in plasma norepinephrine at week 10 (P < 0.05). In the HWE period, changes in haemodynamic and humoral variables were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II and catecholamines interaction in short-term low protein feeding

Renal and systemic hemodynamic responses to an alpha-adrenergic agonist (norepinephrine, NE) and an alpha-adrenergic antagonist (phentolamine, PHEN) were studied in weanling rats pair-fed isocaloric diets containing either normal (NP, 23%) or low (LP, 6%) protein. Mean arterial pressure (MAP) rose less with NE and fell more with PHEN in LP than in NP. Plasma NE and epinephrine (E; 46 +/- 5 and 51 +/- 4 ng/ml) were higher in LP than in NP (26 +/- 3 and 39 +/- 3 ng/ml). These could not be attributed to changes in red cell mass nor the volumes of plasma, extracellular, or interstitial fluid in LP versus NP. Plasma angiotensin II (Ang II), renin (PRA), and aldosterone (PA) were lower in LP than in NP. An increased number without changes in affinity of glomerular Ang II receptors was found in LP compared to NP, while alpha 1- and alpha 2-adrenergic receptors were down-regulated in LP as compared to NP without changes in affinity for the alpha 1 receptor but with an increase in renal alpha 2 receptor affinity. LP (vs. NP) decreased GFR and RPF, and increased renal vascular resistance (RVR). NE decreased RPF equally in NP versus LP but raised RVR approximately twofold in NP versus LP. PHEN decreased RPF and increased RVR less in LP than in NP. Moreover, PHEN increased renal renin content approximately seven-fold over the basal NP values. Exogenous Ang II increased RVR and lowered RPF more in LP than in NP. Enalapril abolished all the hemodynamic changes of LP and restored the systemic response to NE.(ABSTRACT TRUNCATED AT 250 WORDS)

Chloramine-T induced binding of monoclonal antibody B72.3 to concanavalin-A

The effects of chloramine-T (CT) on monoclonal antibody B72.3 were studied with particular reference to Con-A lectin binding. After exposure to chloramine-T concentrations from 0.8 to 4.0 mg/mL (115-574 mol CT/mol B72.3), B.72.3 showed progressive binding to agarose-linked Con-A. This behavior was paralleled by decreasing immunoreactivity and increasing fragmentation and aggregation of B72.3 demonstrated by SDS-PAGE and size exclusion HPLC.

Influence of workload on the antihypertensive effect of exercise

1. The relation between workload and the antihypertensive effect of exercise therapy in hypertensive patients, and the mechanism of that effect, were investigated. 2. Twenty-six patients participated in the study and were randomly assigned to 10 weeks of either low or high workload exercise. In the low workload group, 16 mild hypertensive patients were treated with bicycle ergometer exercise at approximately 50% of their maximum oxygen consumption (VO2max) for 60 min three times a week for 10 weeks. In the high workload group, 10 mild hypertensive patients exercised on the same schedule, but at approximately 75% of VO2max. 3. After 10 weeks of exercise, the low workload group had significantly lower systolic (9 mmHg), mean (6 mmHg) and diastolic (6 mmHg) blood pressures. In the high workload group, decreases in systolic (3 mmHg), mean (4 mmHg) and diastolic (5 mmHg) blood pressure were not statistically significant. 4. In the low workload group, changes in haemodynamic and humoral variables were not significant, except for a reduction in plasma norepinephrine at week 7. Cardiac index and plasma norepinephrine tended to decrease. In the high workload group, plasma norepinephrine and the renin-angiotensin system were transiently stimulated after 4 weeks of exercise. Stroke volume significantly increased (+26.4%) after 10 weeks of high workload exercise. 5. Based on these results and better patient compliance with the exercise programme in the low workload group than in the high workload group, low workload exercise therapy was recommended to mild hypertensive patients.

Dual hemodynamic mechanisms for salt-induced hypertension in Dahl salt-sensitive rats

Cardiac output, blood volume, total peripheral resistance, and renal blood flow were measured in awake salt-sensitive and salt-resistant Dahl rats on normal rat chow (1% NaCl) and on high salt (8% NaCl) diets. Rats were studied after 4, 8, and 46 weeks on a 1% NaCl diet and after 4 and 8 weeks on an 8% NaCl diet. Salt-sensitive rats on 8% NaCl for 4 weeks developed systolic hypertension; by 8 weeks they developed greater systolic and also diastolic hypertension. Salt-resistant rats on 8% NaCl remained normotensive throughout the studies, although renal resistance decreased (p less than 0.05). At 4 weeks, hypertension in salt-sensitive rats on 8% NaCl was caused by increased blood volume and cardiac output (p less than 0.05), with normal total peripheral resistance. At 8 weeks, hypertension was due to increased total peripheral resistance (p less than 0.05); cardiac output was below normal despite persistent elevation of blood volume (p less than 0.05). Salt-sensitive rats on 1% NaCl for 46 weeks were hypertensive, with elevated total peripheral resistance (p less than 0.05); cardiac output decreased (p less than 0.05), whereas blood volume remained unchanged. Salt-resistant rats on 1% NaCl remained normotensive with no charges in hemodynamics. Salt-sensitive rats on 8% NaCl for 4 weeks had an increase in renal vascular resistance but no significant change in nonrenal resistance or total peripheral resistance. The increased total peripheral resistance in salt-sensitive rats on 8% NaCl for 8 weeks and on 1% NaCl for 46 weeks was a reflection of increases of both renal and nonrenal vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of dopamine and atrial natriuretic factor by mild exercise for hypertensives

Changes of humoral factors related to the regulation of fluid volume were investigated in exercise training for hypertensives. Twelve patients with essential hypertension were treated with an aerobic exercise for 10 weeks. A significant reduction in blood pressure from 161 +/- 3/100 +/- 2 mmHg at week 0 to 142 +/- 5/94 +/- 3 mmHg at week 4 was observed which continued until week 10. Urine dopamine was increased significantly at the 4th week from 386 +/- 29.4 micrograms/day at week 0 to 524 +/- 46.3 micrograms/day and plasma atrial natriuretic factor (ANF) was significantly reduced at the 4th week, from 41.5 +/- 2.7 pg/ml at week 0 to 32.6 +/- 3.7 pg/ml. Plasma volume was found reduced significantly from 2,531 +/- 166 ml/m2 at week 0 to 2,221 +/- 165 ml/m2 at week 10. These results suggest that the increase of dopamine and reduction of plasma ANF which took place at the early stage might be related to, at least in part, the depletion of plasma volume and the reduction of blood pressure in mild exercise for hypertensives.

Salt-induced hypertension in Dahl salt-sensitive rats. Hemodynamics and renal responses

This study was performed with Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats to detect differences in cardiovascular hemodynamics and renal responses that might be involved in initiating salt-induced hypertension in DS rats. The effects of 4 weeks of 8% NaCl diet were studied in conscious, male DR and DS rats in which vascular and urinary catheters had been previously implanted. Results were compared with those obtained from control groups of DR and DS rats on 4 weeks of 1% NaCl diet. DR rats on 8% salt diet did not develop hypertension, and cardiac output and blood volume were unchanged; glomerular filtration rate, urinary flow, sodium excretion, and plasma atrial natriuretic factor (ANF) increased. DS rats on 8% salt diet developed hypertension, and cardiac output and blood volume increased; glomerular filtration rate, urinary flow, and sodium excretion did not change, despite an increase in ANF. DS and DR rats on 1% NaCl diet were subjected to ANF infusion. After ANF infusion DR rats had a decreased blood volume and an increased glomerular filtration rate, urinary flow, and sodium excretion; DS rats showed no significant changes in blood volume, glomerular filtration rate, urinary flow, or sodium excretion. ANF caused vasodilation in all regions studied in DR rats; DS rats showed vasodilation in all regions except the kidney. After acute volume expansion, although both DR and DS rats responded by an increase in cardiac output, only DS rats developed prolonged hypertension. This finding suggests an inadequate vasodilatory mechanism in DS rats. In response to acute volume expansion, renal resistance decreased in DR rats but not in DS rats. It is concluded that the primary hemodynamic disturbance in DS rats with salt-induced hypertension is an increase in cardiac output caused by blood volume expansion in the absence of any vasodilation. Comparison of the responses of DS and DR rats to high salt diets, ANF infusion, and acute volume expansion indicates that the salt-induced hypertension in DS rats is initiated by a diminished renal response to ANF.

Intestinal adaptation during lactation in the mouse. I. Enhanced intestinal uptake of dietary protein antigen

Small quantities of dietary protein antigens cross the intestinal epithelium of the lactating mouse, enter the circulation, are transferred across the mammary gland into the milk and reach the suckling neonate. In this study, we sought to determine whether intestinal uptake of ovalbumin (OVA) was enhanced in lactating compared to control mice. OVA was administered by gavage under ether anaesthesia. Blood was obtained at 15, 30, 60 and 120 min and immunoreactive OVA (iOVA) measured by enzyme immunoassay. At 30 and 60 min, a three- to four-fold higher concentration of iOVA was detected in lactating compared to control mice. Because this increase in concentration of iOVA might be explained by changes in plasma volume, rate of clearance of OVA from the circulation or altered uptake from the intestine, plasma volume was measured by isotope dilution after i.v. injection of 125I-bovine serum albumin (BSA) and clearance was assessed by measuring elimination of OVA from the circulation after i.v. injection of OVA. In comparison to controls, plasma volume of Day 7-10 lactating mice was increased two-fold and no difference in clearance rate was noted. Because the increase in concentration of iOVA in lactating mice is several-fold greater than in controls, we suggest that increased intestinal uptake of the protein occurs during lactation.

Changes in serum concentrations of taurine and other amino acids in clinical antihypertensive exercise therapy

Thirty-one Japanese with essential hypertension were divided into training (n = 21) and non-training (n = 10) groups. Physical training of 10 weeks was instituted after 4 or more weeks of observation, and changes in blood pressure and serum concentrations of taurine and other amino acids were investigated. The workload in physical training was predetermined by the submaximal multistage graded exercise test on a bicycle ergometer, and the blood lactate threshold which reflects approximately 40-60% of maximal oxygen uptake was chosen. The hypertensive patients underwent bicycle ergometer training for 60 minutes, three times a week for 10 weeks. Blood pressures were significantly decreased by 14.8/6.6 mmHg in systole/diastole in the training group, but not in the non-training group. Serum concentrations of taurine and cystine were increased significantly by 26% and 287%, in the training group. Increase in serum asparagine (11%), histidine (6%) and lysine (7%) concentrations was also significant, only in the training group. Plasma norepinephrine level and whole blood and plasma volumes were significantly reduced. The change in serum taurine level was significantly negatively correlated with the change in plasma norepinephrine. In addition there was a significant positive correlation between the change in plasma norepinephrine and the change in diastolic blood pressure in the training group. Based on these results, the increase in serum taurine which is known for its antihypertensive activity could contribute, at least in part through the reduction in plasma norepinephrine level, to the antihypertensive effect of exercise.

Antihypertensive and volume-depleting effects of mild exercise on essential hypertension

After a general clinical observation period of over 4 weeks, 20 essential hypertensive subjects (Japanese) were randomly divided into two groups. One group (n = 10; 4 men and 6 women; 51.4 +/- 2.8 years of age) agreed to physical training using bicycle ergometer exercise with the intensity at blood lactate threshold for 60 minutes three times a week for 10 weeks, while the other group (n = 10; 4 men and 6 women; 51.0 +/- 2.9 years of age) did no particular physical training and was followed once a week as the control. Changes in blood pressure, hemodynamics, and humoral factors of the exercised group were compared with values in the controls. The following significant changes were found only in the exercised group. Blood pressure was significantly (p less than 0.01) reduced. Whole blood and plasma volume indices were significantly reduced (p less than 0.05, p less than 0.01, respectively). The change in ratio of serum sodium to potassium positively correlated with the change in systolic blood pressure (r = 0.76, p less than 0.02). Plasma norepinephrine concentrations both at rest and at the workload of blood lactate threshold during graded exercise tests were significantly reduced (p less than 0.05, p less than 0.02 respectively) after 10 weeks of exercise training. The change in the resting level of plasma norepinephrine positively correlated with that in the mean blood pressure. No such changes were observed in the control group. In both groups, body weight and urinary sodium excretion showed no statistically significant changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoglobulin abnormalities in patients with myotonic dystrophy

In order to further investigate immunoglobulin (Ig) abnormalities in patients with myotonic dystrophy (MyD), we examined 65 patients with MyD for their serum concentration of IgG in relation to their immunological functions as well as other clinical and laboratory findings. Turnover of IgG was also examined. We found significant and selective reduction of serum IgG in patients with MyD. The serum concentration of IgG in patients with MyD had a significant negative correlation with duration of illness, which suggested that serum IgG levels in MyD decreased constantly throughout the disease course. Peripheral blood lymphocyte subpopulations, including functional T cell subsets, in vitro lymphocyte proliferation, and in vitro IgG production were normal. The plasma cell population in bone marrow was also normal. The IgG turnover study using 125I-labelled IgG as a tracer revealed an increased extravascular IgG pool, and an increased capillary permeability of intravascular IgG into the extravascular compartment, in patients with MyD. These observations suggested that the Ig abnormalities in patients with MyD were not due to a broader immunological derangements as previously postulated by other authors. The abnormal distribution of IgG is a possible factor leading to reduced serum concentration of IgG in patients with MyD.

[A modified dye dilution method to estimate leakage during regional isolated perfusion of the extremity (author's transl)]

In experiments on dogs (n=13) we tested a procedure for estimating leakage during regional perfusion of the extremity by means of a dye dilution method. After systematic application of 0.5% Evans blue solution (0.1 ml/kg b.w.) we measured the dye concentration in plasma by means of a spectral photometer. The plasma volume (5.5 ml/100 gb.w.) and the disappearance rate of the dye (10%/h) were calculated. In a second procedure the supplying artery and vein of the extremity were proximally clamped and distally connected to an extracorporeal circulation unit consisting of oxygenator, pump, and heat exchanger, and the isolation of the extremity was tested. By simulated of leakage it was possible to detect a little amount of shunt of about 1% escaping from isolated region into the systemic circulation. There were no hints to toxicity when the same dye concentration. There were no hints to toxicity when the same dye concentration was applied. The standardized method was using during 132 cytostatic hyperthermic perfusion in man. In 20 patients we determined shunts of less than 5%, in 104 patients shunts between 5 and 10%, and in eight patients shunts of 10-20% of the extracorporeal circulation. The benefits of the described method are simplicity to carry out and missing of toxicity or radiation.

Mechanism of reduced glomerular filtration rate in chronic malnutrition

To determine the physiological basis for the low glomerular filtration rate in chronic malnutrition, micropuncture studies were performed in Munich-Wistar rats chronically pair-fed isocaloric diets of either low (group 1, nine rats) or high protein content (group 2, nine rats). Despite the absence of hypoalbuminemia, average values for single nephron and total kidney glomerular filtration rate were nearly 35% lower in group 1 than in group 2. Mean values for glomerular capillary and Bowman's space hydraulic pressures were essentially identical in the two groups, thereby excluding glomerular transcapillary hydraulic pressure difference as the cause for the low filtration rates in group 1 animals. On the other hand, average glomerular capillary plasma flow rate and glomerular capillary ultrafiltration coefficient were significantly lower (by approximately 25 and approximately 50%, respectively) in group 1 than in group 2. The fall in glomerular capillary plasma flow rate was the consequence of increased afferent and efferent arteriolar resistances. Plasma and erythrocyte volumes were found to be equal in five additional pairs of group 1 and group 2 rats. Thus, the substantial alterations in the ultrafiltration coefficient, glomerular capillary plasma flow rate, and renal arteriolar resistances responsible for the low filtration rate in group 1 animals were not merely a consequence of decreased circulating blood or plasma volumes. Mean values for glomerular cross sectional area were significantly lower in group 1 than in group 2 despite similar values for kidney weight in the two groups. This reduction in glomerular cross sectional area in group 1 rats is presumed to reflect a decrease in effective filtration surface area and therefore likely accounts, at least in part, for the decline in ultrafiltration coefficient observed in this group.Finally, since the daily caloric intake of group 2 animals was restricted because of pair feeding requirements tied to the group 1 rats, we studied a third group of seven rats (group 3) allowed an ad lib. intake of the same high protein diet as given to group 2 rats. Average values for single nephron glomerular filtration rate and its determinants were found to be indistinguishable between groups 2 and 3. These results suggest that low protein intake, rather than calorie deficiency per se, is primarily responsible for the reduction in filtration rate seen in this experimental model of chronic malnutrition.

Haemodynamic effects of splenectomy and vasoligation in bilharzial hepatic fibrosis

Patients with bilharzial hepatic fibrosis, when compared with control subjects, were found to be hypervolaemic as a result of increased plasma volume. The estimated hepatic blood flow in these patients was not significantly different from that of healthy individuals. Splenectomy and vasoligation was followed by a drop in portal pressure measured through an omental vein at operation. The estimated hepatic blood flow, however, was not altered by this surgical procedure. The blood volume, which was found to correlate with the size of the spleen, diminished and so did the plasma volume when measured after this operation.

Role of the renin-angiotensin-aldosterone system in hypertensive children with coarctation of the aorta

To investigate the role of the renin-angiotensin-aldosterone system as a cause of hypertension, 20 hypertensive patients with coarctation of the aorta were studied during normal and low sodium intake and after diuresis with flurosemide. Eight patients with essential hypertension and 13 control subjects were similarly studied. Plasma renin activity values in patients with coarctation were similar to those in patients with essential hypertension and in control patients during normal and low sodium diets. However, after the administration of furosemide, plasma renin activity values were significantly higher in the patients with coarctation than in the other two groups (P less than 0.005 and less than 0.01, respectively). The values for urinary aldosterone, plasma volume and extracell fluid volume (bromide space) were increased in patients with coarctation during both normal and low sodium intake. These renin and aldosterone responses and body fluid spaces in patients with coarctation suggest that their hypertension resembles a one-kidney Goldblatt model. The data help to better define the role of the renin-angiotensin-aldosterone system in the hypertension of coarctation and thus may help guide the clinician in therapeutic interventions.

Plasma volume estimation in severely ill infants and children using a simplified Evans blue method

Plasma volume was measured using Evans blue dye and 125iodinated human serum albumin (RIHSA) simultaneously in order to evaluate the accuracy of a simplified Evans blue method recommended by Nielsen and Nielsen (1962). 9 studies were performed in 8 newborn infants weighing 1.07 to 2.85 kg and 16 studies in 14 patients aged 6 months to 14 years suffering from severe circulatory disturbances. In 20 studies, plasma volumes measured by Evans blue and by RIHSA agreed within +/-5%, and in all the studies within +/-10%. The Evans blue method yielded higher plasma volumes than the RIHSA method in 19 instances. The mean difference (paired t-test) was only significant in newborn infants (+4.0+/-3.6%; P less than 0.05). The disappearance rates of Evans blue exceeded that of RIHSA in 16 studies, but this was only significant in the patients older than 6 months (+2.3+/-4.2%/h; P less than 0.05).

Ferrokinetic studies in acute myocardial infarction

Serum iron levels were determined in 16 patients with AMI at different days following the event and in five patients either treated with steroids or suffering from diseases acting as stress factors. Patients with AMI showed a marked decrease in serum iron concentrations, the lowest value being recorded at day 3 after the event; serum iron returned to normal level at day 12. These alterations in iron concentration were not accompanied by changes in the 24 hour urine excretion of iron. On the other hand, a significant shortening of the half-time 59Fe plasma clearance and an early increase in 59Fe incorporation into the red blood cells were found immediately after the event. These values returned to normal in all but one patient, who had in addition polycythemia. In the five patients comprising the control group, serum iron, iron excretion in urine, and ferrokinetics were within the normal limits at all times. Since in AMI patients the 11-OHCS values were found to be significantly higher on the day following the infarction than on day 15 after the event, it is suggested that the decrease in iron concentration in these patients may be connected with changes in plasma 11-OHCS levels.

Hypersplenism in Wilson's disease

Thirteen patients with Wilson's disease were compared with seven cirrhotic and 13 normal controls to define better the haematological abnormalities in this condition. Hypersplenism (anaemia, leukopenia, thrombocytopenia, and reduced red cell survival) commonly occurred in patients with both Wilson's disease and cirrhosis. These abnormalities correlated with splenic enlargement. Despite reduced haematocrits, red cell mass was greater in these two groups than in normal controls. Plasma volume and the body haematocrit/peripheral haematocrit ratios were also greater in patients with Wilson's disease and cirrhosis. Increased splenic sequestration of (51)Cr-tagged red blood cells was not demonstrated in any subjects. The hypersplenism in patients with Wilson's disease is similar to that found in patients with cirrhosis from other causes.

Regression of body compositional abnormalities of heart failure after intracardiac operations

Alterations in body composition are present in patients with heart disease and congestive heart failure, and additional changes occur acutely after corrective surgery. The reversibility and time course of reversion to normal body composition have not been demonstrated. Nine patients were studied preoperatively and 2 to 4 weeks and 6 to 12 mo postoperatively. Measurements were made, using the isotope-dilution technic, of the volumes of total body water, extracellular water, plasma, and red cells, and of the amounts of total exchangeable sodium and potassium. Values were derived for body fat, indices of body cell mass, and the intracellular and extracellular distribution of water and potassium. Significant changes ( P < 0.05) occurring 2 to 4 weeks after operation were increased in total body water (8.2%), intracellular water (15.0%), exchangeable sodium (7.1%), and intracellular potassium content (7.7%), and decrease in body weight (4.6%) and body fat (21.6%); 6 to 12 mo postoperatively there was increase in exchangeable potassium (6.8%), body weight (7.8%), and decrease in exchangeable sodium (16.1%), extracellular fluid (7.8%), plasma (8.0%), and the ratio of exchangeable sodium to exchangeable potassium (23.6%). Late postoperative values were similar to predicted normal values and indicate that postoperative recovery from valvular replacement in these patients is accompanied by resolution of most of the body compositional abnormalities of heart failure.

Acute alterations of body composition after open intracardiac operations

The body composition of patients with heart disease is acutely altered by surgical intervention. Interrelations and causes of the alterations have not been clear. Twenty patients were studied preoperatively and again 2 to 4 days after open intracardiac operations. In nine, measurements were made of the volumes of total body water, extracellular water, plasma, and red cells, and of the amounts of total exchangeable sodium and potassium. In an additional four patients total exchangeable sodium and potassium were measured, and in another seven only exchangeable sodium was measured. Calculations were made of the intracellular and extracellular distribution of water and potassium. The significant changes ( P < 0.05) occurring during the interval between studies were increase in extracellular water (7%), interstitial water (12.5%), and exchangeable sodium (9.4%), decrease in total exchangeable potassium (8.5%) and amount (8.7%), and concentration (6.9%) of calculated intracellular potassium. Uptake of sodium and water by the patient during cardiopulmonary bypass and postoperative loss of intracellular potassium with its secondary renal excretion are postulated as being etiologic. These findings imply that sodium intake in the early postoperative period should be low, water intake no more than urinary and insensible losses, and that potassium should be administered.