Effects of saline, mannitol, and furosemide on acute decreases in renal function induced by radiocontrast agents

BACKGROUND

Injections of radiocontrast agents are a frequent cause of acute decreases in renal function, occurring most often in patients with chronic renal insufficiency and diabetes mellitus.

METHODS

We prospectively studied 78 patients with chronic renal insufficiency (mean [+/- SD] serum creatinine concentration, 2.1 +/- 0.6 mg per deciliter [186 +/- 53 mumol per liter]) who underwent cardiac angiography. The patients were randomly assigned to receive 0.45 percent saline alone for 12 hours before and 12 hours after angiography, saline plus mannitol, or saline plus furosemide. The mannitol and furosemide were given just before angiography. Serum creatinine was measured before and for 48 hours after angiography, and urine was collected for 24 hours after angiography. An acute radiocontrast-induced decrease in renal function was defined as an increase in the base-line serum creatinine concentration of at least 0.5 mg per deciliter (44 mumol per liter) within 48 hours after the injection of radiocontrast agents.

RESULTS

Twenty of the 78 patients (26 percent) had an increase in the serum creatinine concentration of at least 0.5 mg per deciliter after angiography. Among the 28 patients in the saline group, 3 (11 percent) had such an increase in serum creatinine, as compared with 7 of 25 in the mannitol group (28 percent) and 10 of 25 in the furosemide group (40 percent) (P = 0.05). The mean increase in serum creatinine 48 hours after angiography was significantly greater in the furosemide group (P = 0.01) than in the saline group.

CONCLUSIONS

In patients with chronic renal insufficiency who are undergoing cardiac angiography, hydration with 0.45 percent saline provides better protection against acute decreases in renal function induced by radiocontrast agents than does hydration with 0.45 percent saline plus mannitol or furosemide.

The Spinal Cord Independence Measure (SCIM) version III: Reliability and validity in a multi-center international study

PURPOSE

To examine the third version of the Spinal Cord Independence Measure (SCIM III) for reliability and validity in a multi-center cohort study.

METHOD

Four hundred and twenty-five patients with spinal cord lesions from 13 spinal cord units in six countries from three continents were assessed with SCIM III and the Functional Independence measure (FIM) on admission to rehabilitation and before discharge.

RESULTS

Total agreement between raters was above 80% in most SCIM III tasks, and all kappa coefficients were statistically significant (P<0.001). The coefficients of Pearson correlation between the paired raters were above 0.9, and intraclass correlation coefficients were above 0.94. Cronbach's alpha was above 0.7. The coefficient of Pearson correlation between FIM and SCIM III was 0.790 (P<0.01). SCIM III was more responsive to changes than FIM in the subscales of Respiration and sphincter management and Mobility indoors and outdoors.

CONCLUSIONS

The results support the reliability and validity of SCIM III in a multi-cultural setup. Despite several limitations of the study, the results indicate that SCIM III is an efficient measure for functional assessment of SCL patients and can be safely used for clinical and research trials, including international multi-center studies.

Elevated 1,25-dihydroxyvitamin D plasma levels in normal human pregnancy and lactation

Plasma 1,25-dihydroxyvitamin D levels are elevated in early pregnancy and continue to increase throughout pregnancy. They remain elevated postpartum in lactating women. The elevated levels probably represent a physiological response to increased calcium requirements.

A multicenter international study on the Spinal Cord Independence Measure, version III: Rasch psychometric validation

BACKGROUND

A third version of the Spinal Cord Independence Measure (SCIM III), made up of three subscales, was formulated following comments by experts from several countries and Rasch analysis performed on the previous version.

OBJECTIVE

To examine the validity, reliability, and usefulness of SCIM III using Rasch analysis.

DESIGN

Multicenter cohort study.

SETTING

Thirteen spinal cord units in six countries from North America, Europe, and the Middle-East.

SUBJECTS

425 patients with spinal cord lesions (SCL).

INTERVENTIONS

SCIM III assessments by professional staff members. Rasch analysis of admission scores.

MAIN OUTCOME MEASURES

SCIM III subscale match between the distribution of item difficulty grades and the patient ability measurements; reliability of patient ability measures; fit of data to Rasch model requirements; unidimensionality of each subscale; hierarchical ordering of categories within items; differential item functioning across classes of patients and across countries.

RESULTS

Results supported the compatibility of the SCIM subscales with the stringent Rasch requirements. Average infit mean-square indices were 0.79-1.06; statistically distinct strata of abilities were 3 to 4; most thresholds between adjacent categories were properly ordered; item hierarchy was stable across most of the clinical subgroups and across countries. In a few items, however, misfit or category threshold disordering were found.

CONCLUSIONS

The scores of each SCIM III subscale appear as a reliable and useful quantitative representation of a specific construct of independence after SCL. This justifies the use of SCIM in clinical research, including cross-cultural trials. The results also suggest that there is merit in further refining the scale.

Independent and incremental prognostic value of Doppler-derived mitral deceleration time of early filling in both symptomatic and asymptomatic patients with left ventricular dysfunction

OBJECTIVES

This study sought to investigate the relative and incremental prognostic value of demographic, historical, clinical, echocardiographic and mitral Doppler variables in patients with left ventricular systolic dysfunction.

BACKGROUND

The prognostic value of diastolic abnormalities as assessed by mitral Doppler echocardiography has yet to be defined.

METHOD

A total of 508 patients with left ventricular ejection fraction < or = 35% were followed up for a mean (+/- SD) period of 29 +/- 11 months.

RESULTS

During the follow-up period, 148 patients (29.1%) were admitted to the hospital for congestive heart failure, and 100 patients (19.7%) died. By Cox model analysis, Doppler-derived mitral deceleration time of early filling < or = 125 ms (relative risk [RR] 1.93, 95% confidence interval [CI] 1.4 to 3.7), New York Heart Association functional class III or IV (RR 1.49, 95% CI 1.4 to 2.3), ejection fraction < or = 25% (RR 1.85, 95% CI 1.6 to 2.9), third heart sound (RR 2.06, 95% CI 1.8 to 3.2), age > 60 years (RR 1.95, 95% CI 1.8 to 3.1) and left atrial area > 18 cm2 (RR 1.73, 95% CI 1.6 to 2.7) were all found to be independent and additional predictors of all-cause mortality, and deceleration time was the single best predictor (chi-square 37.80). When all these significant variables were analyzed in hierarchic order, after age, functional class, third sound, ejection fraction and left atrial area, deceleration time still added significant prognostic information (global chi-square from 9.2 to 104.7). Also, deceleration time was the strongest independent predictor of hospital admission for congestive heart failure (RR 4.88, 95% CI 3.7 to 6.9) and cumulative events (congestive heart failure or all-cause mortality, or both; RR 2.44, 95% CI 2.0 to 3.8) in both symptomatic and asymptomatic patients.

CONCLUSIONS

Deceleration time of early filling is a powerful independent predictor of poor prognosis in patients with left ventricular systolic dysfunction, whether symptomatic or asymptomatic. A short (< or = 125 ms) deceleration time by mitral Doppler echocardiography adds important prognostic information compared with other clinical, functional and echocardiographic variables.

Obsessive-compulsive disorder in a birth cohort of 18-year-olds: prevalence and predictors

OBJECTIVE

To report descriptive epidemiological information on obsessive-compulsive disorder (OCD) in an unselected birth cohort of 930 males and females, aged 18 years.

METHOD

An epidermiological study of the prevalence of self-reported OCD at age 18, and a longitudinal analysis of the prospective predictors of OCD.

RESULTS

Using the Diagnostic Interview Schedule, the authors found a 1-year prevalence rate of 4%, with a male-female ratio of 0.7:1. The majority of OCD cases met criteria for a comorbid disorder, most commonly depression (62%), social phobia (38%), and substance dependence (alcohol 24%, marijuana 19%).

CONCLUSIONS

Data collected on the sample from birth to age 18 years indicated that many childhood risk factors theorized in the literature did not predict OCD in this sample. However, a history of depression and substance use were prospective risk factors for OCD.

Selective vulnerability of the medullary thick ascending limb to anoxia in the isolated perfused rat kidney

A specific anatomical lesion sharply localized to the cells of the medullary thick ascending limbs (mTAL) and characterized by mitochondrial swelling progressing to nuclear pyknosis and cell death is elicited reproducibly in isolated rat kidneys perfused for 15 or 90 min with cell-free albumin-Ringer's medium gassed with 5% CO2, 95% O2 (O2 content, 1.5 vol/100 ml). The lesion, involving about half of mTALs, appears first in mTALs removed from vascular bundles and near the inner medulla, areas most likely to be anoxic. Hypoxic perfusion (O2 content 0.12 vol/100 ml) exaggerates the lesion, wiping out gradations of damage and extending it to all mTALs. O2-enriched perfusions using rat erythrocytes (O2 content 7.1 vol/100 ml) completely eliminates the lesion (unless gassed with carbon monoxide). Similarly, supplementation of the perfusion medium with a purified hemoglobin (O2 content 5.8 vol/100 ml) prevents mTAL injury. Perfusion with a fluorinated hydrocarbon blood substitute, Oxypherol (O2 content 4.3 vol/100 ml) also attenuates the lesion. These findings suggest that the mTAL is exquisitely susceptible to anoxic damage because of low O2 supply imposed by the medullary vascular system and the high rate of metabolism mandated by active reabsorption of sodium chloride. The vulnerability of the mTAL to anoxic injury could play a key role in the pathogenesis of ischemic renal injury.

Early renal medullary hypoxic injury from radiocontrast and indomethacin

We evaluated the acute changes in cortical and outer medullary oxygen tension and the alterations in renal function and morphology within the first 90 minutes after the administration of indomethacin and iothalamate to anesthetized Sprague-Dawley rats. Both agents were found to produce marked and protracted outer medullary hypoxia averaging 12 +/- 4 and 9 +/- 2 mm Hg, respectively (mean +/- SE). Given together to salt depleted uninephrectomized rats they produced an early hypoxic injury localized selectively in the outer medulla. This lesion progressed from 3 +/- 1% of medullary thick ascending limbs (mTALs) at 15 minutes to 22 +/- 7% at 24 hours. Condensed "dark" cells were observed at 15 minutes, probably representing a type of early injury. Residual red cell mass, quantified in the outer medullary vasculature of perfusion-fixed kidneys and presumably reflecting stasis, was substantially increased in iothalamate treated rats. Red cell mass in the interbundle zone correlated with mTAL necrosis. Taken together, these results show an early period of medullary hypoxia, accompanied by a selective injury to mTALs in the central interbundle zone with apparent stasis. These findings contrast sharply with the ischemia-reflow pattern of renal damage and emphasize the important role of medullary hypoxia in the genesis of acute renal failure in this model.

Adrenergic modulation of extrarenal potassium disposal

We studied the role of catecholamines in the regulation of potassium homeostasis in nine healthy subjects given intravenous potassium chloride (0.5 meq per kilogram of body weight) in the presence and absence of propranolol. Potassium infusion elevated serum potassium 0.6 +/- 0.09 meq per liter (mean +/-S.E.M.). Addition of propranolol augmented the rise (0.9 +/- 0.05 meq per liter) and prolonged the elevation in serum potassium without decreasing urinary potassium excretion. In a separate study, the same potassium load was administered with a concomitant infusion of epinephrine in five subjects. Epinephrine markedly blunted the increment in serum potassium (0.1 +/- 0.06 meq per liter) while reducing renal potassium excretion. Plasma aldosterone was not altered by the experimental procedures. Serum insulin fell minimally in the presence of propranolol but was unaffected by epinephrine. beta-Adrenergic blockade impairs and epinephrine enhances extrarenal disposal of an acute potassium load. These findings suggest that in patients with impaired potassium disposal, the risk of hyperkalemia may be increased when sympathetic blockade is induced.

Why are children born to teen mothers at risk for adverse outcomes in young adulthood? Results from a 20-year longitudinal study

This 20-year longitudinal study showed that the young adult offspring of teen mothers are at risk for a range of adverse outcomes including early school leaving, unemployment, early parenthood, and violent offending. We tested how much the effect of teen childbearing on offspring outcomes could be accounted for by social selection (in which a woman's characteristics that make her an inadequate parent also make her likely to bear children in her teens) versus social influence (in which the consequences of becoming a teen mother also bring harm to her children, apart from any characteristics of her own). The results provided support for both mechanisms. Across outcomes, maternal characteristics and family circumstances together accounted for approximately 39% of the effect of teen childbearing on offspring outcomes. Consistent with a social-selection hypothesis, maternal characteristics accounted for approximately 18% of the effect of teen childbearing on offspring outcomes; consistent with a social-influence hypothesis, family circumstances accounted for 21% of the teen childbearing effect after controlling for maternal characteristics. These results suggest that public policy initiatives should be targeted not only at delaying childbearing in the population but at supporting individual at-risk mothers and their children.

Ouabain inhibition of gill Na-K-ATPase: relationship to active chloride transport

Ouabain circulating in blood inhibits Na-K-ATPase in the gills of seawater eels at a concentration similar to that necessary for inhibition in vitro. By contrast, a much higher concentration is required when ouabain is applied to the exterior of the gill. Inhibition by external ouabain occurs only when the drug gains access to the circulation of the fish, as evidenced by simultaneous inhibition of Na-K-ATPase in the kidney. These results suggest that the Na-K-ATPase of gill chloride cells faces inward, lining intracytoplasmic tubular channels continuous with the extracellular fluid. Inhibition of gill Na-K-ATPase by ouabain in intact salt water eels results in almost complete inhibition of the efflux of both Na+ and Cl-. The efflux is tritiated water was much less reduced, to 60% of normal. Since chloride is actively transported outward across the gill of seawater teleosts, it is suggested that active chloride transport is coupled to Na-K-ATPase. A neutral sodium chloride carrier is postulated that is energized by the movement of sodium from extracellular fluid down its electrochemical gradient into the chloride cell.

Transport activity modifies thick ascending limb damage in the isolated perfused kidney

The thick ascending limb of Henle's loop ( TAL ) develops a specific and consistent structural lesion during perfusion of the isolated rat kidney that progresses from mitochondrial swelling at 15 min to complete cellular disruption at 90 min. Because it seemed possible that damage localized to this metabolically active portion of the nephron might be correlated with cellular transport, the histology of perfused kidneys was examined when transport activity in the TAL was varied. The fraction of TAL tubules showing severe damage (44 +/- 2% in kidneys perfused with glucose) was dramatically reduced by furosemide (7 +/- 2%; P less than 0.001). The lesion was eliminated by perfusion with ouabain or by preventing glomerular filtration. On the other hand, protection of TAL cells was not obtained with the proximal diuretic acetazolamide. These results suggest that the lesion of TAL cells that develops during perfusion of the isolated kidney is influenced by the work of cellular transport.

Atrial natriuretic peptides inhibit conductive sodium uptake by rabbit inner medullary collecting duct cells

The inner medullary collecting duct (IMCD) effects net sodium reabsorption under the control of volume regulatory hormones, including atrial natriuretic peptides (ANP). These studies examined the mechanisms of sodium transport and its regulation by ANP in fresh suspensions of IMCD cells. Sodium uptake was inhibited by amiloride but insensitive to furosemide, bu-metanide, and hydrochlorthiazide. These results are consistent with uptake mediated by a sodium channel or Na+/H+ exchange. To determine the role of sodium channels, cells were hyperpolarized by preincubation in high potassium medium followed by dilution into potassium-free medium. Membrane potential measurements using the cyanine dye, Di(S)-C3-5 verified a striking hyperpolarization of IMCD cells using this protocol. Hyperpolarization increased the apparent initial rate of sodium uptake fourfold. Amiloride and ANP inhibited potential-stimulated sodium uptake 73% and 65%, respectively; the two agents together were not additive. Addition of 5 mM sodium to hyperpolarized cells resulted in a significant amiloride-sensitive depolarization. Half-maximal inhibition of potential-driven sodium uptake occurred at 3 X 10(-7) M amiloride, and 5 X 10(-11) M ANP. We conclude that sodium enters IMCD cells via a conductive, amiloride-sensitive sodium channel, which is regulated by ANP. ANP inhibition of luminal sodium entry in the IMCD appears to contribute to the marked natriuretic effect of this hormone in vivo.

The importance of conduct problems and depressive symptoms in predicting adolescent substance use

The current study assessed the relative importance of conduct problems and depressive symptoms, measured at two ages (11 and 15), for predicting substance use at age 15 in an unselected birth cohort of New Zealand adolescents. Among males, when the relative predictive utility of both conduct problems and depressive symptoms was assessed, only pre-adolescent depressive symptoms were found to predict multiple drug use 4 years later. No predictive relation was found between early symptomatology and later substance use among females. The strongest association between predictors and substance use emerged between age 15 multiple drug use and concurrent conduct problems for both males and females. Finally, both conduct problems and depressive symptoms at age 15 were also found to be associated with concurrent "self-medication" among females.

Catecholamine modulation of rapid potassium shifts during exercise

Plasma potassium rises during muscular exercise and falls rapidly when exercise is stopped. Since the sympathoadrenal system is stimulated with exertion and both alpha- and beta-adrenergic agonists affect internal potassium homeostasis, we studied the influence of catecholamines on potassium shifts during and after exercise. Six healthy subjects were given maximal exercise stress tests under three conditions: with no medication (control), during beta-blockade with propranolol, and during alpha-blockade with phentolamine. Compared with a peak rise in plasma potassium of 1.23 +/- 0.27 mmol per liter (mean +/- S.E.M.) during the control study, propranolol caused a rise of 1.89 +/- 0.35 (P less than 0.01) and a sustained elevation during recovery. Phentolamine diminished the rise of potassium (0.70 +/- 0.21 mmol per liter; P less than 0.01) and lowered the potassium level throughout recovery. These effects of catecholamines were independent of the venous pH, the plasma bicarbonate and serum glucose levels, and urinary potassium excretion, and they did not appear to be due to insulin. High norepinephrine and epinephrine levels confirmed the release of catecholamines capable of stimulating alpha- and beta-receptors. Exercise work did not differ among the groups. beta-Adrenergic receptors appear to moderate the acute hyperkalemia of exercise, whereas alpha-adrenergic receptors act to enhance hyperkalemia and may protect against hypokalemia when exertion ceases.

Prospective evaluation of a model of prediction of invasive bacterial infection risk among children with cancer, fever, and neutropenia

A risk prediction model for invasive bacterial infection (IBI) was prospectively evaluated among children presenting with cancer, fever, and neutropenia. The model incorporated assessment of 5 previously identified risk factors: serum level of C-reactive protein (CRP) >/=90 mg/L, hypotension, identification of relapse of leukemia as the cancer type, platelet count of </=50,000 platelets/mm(3), and recent receipt of chemotherapy [16]. Children were uniformly evaluated at enrollment and were classified as having high or low risk for IBI according to a model that considers the number and type of variables present. Of the 263 febrile episodes evaluated during a 17-month period, 140 (53%) were in IBI-positive children. The sensitivity, specificity, and positive and negative predictive values of the model were 92%, 76%, 82%, and 90%, respectively. Identification of these 5 risk factors during the first 24 h of hospitalization was helpful in discriminating between children with a high or low risk for IBI.

Renal failure following major angiography

Acute renal failure following angiography with contrast agents is known to occur, but the circumstances and frequency of its occurrence are not well described. A retrospective review of consecutive angiographic procedures performed over a six month interval revealed a 12 per cent incidence of renal failure following angiography. The degree of failure was severe in approximately 30 per cent of these cases and was associated with a significant mortality even though renal function usually recovered. The occurrence of renal failure was associated with the presence of renal insufficiency, impaired liver function, diabetes mellitus, hypoalbuminemia and proteinuria at the time of angiography to a statistically significant level. Furthermore, combinations of these factors, particularly preexisting combined renal insufficiency and impaired liver function, were associated with an increased incidence of acute renal failure. It is concluded that angiography poses a significant hazard to patients with underlying medical problems, particularly those involving the excretory routes of the contrast agent.

First sexual intercourse: age, coercion, and later regrets reported by a birth cohort

OBJECTIVES

To investigate how age at first sexual intercourse is related to the reported circumstances and to determine how these corresponded to views in early adulthood about its timing.

DESIGN

Cross sectional study within a birth cohort using a questionnaire presented by computer.

SETTING

Dunedin, New Zealand in 1993-4.

SUBJECTS

477 men and 458 women enrolled in the Dunedin Multidisciplinary Health and Development Study, comprising 92% of survivors of the cohort.

RESULTS

The median age at first intercourse was 17 years for men and 16 years for women. Only one man (0.2%) but 30 (7%) women reported being forced to have intercourse on the first occasion. For women, there were increasing rates of coercion with younger age at first intercourse. More men than women reported that they and their partner were equally willing (77% (316/413) v 53% (222/419)). Mutual willingness of both partners was greater for those who reported that it was also the first time for their partner. Timing of first intercourse was considered about right by 49% (200/411) of men and 38% (148/388) of women. Many women (54% (211/388) reported that they should have waited longer, and this rose to 70% (90/129) for women reporting intercourse before age 16.

CONCLUSIONS

Most women regretted having sexual intercourse before age 16. First intercourse at younger ages is associated with risks that are shared unequally between men and women. This information is important to young people themselves.

Whole blood serotonin relates to violence in an epidemiological study

BACKGROUND

Clinical and animal studies suggest that brain serotonergic systems may regulate aggressive behavior; however, the serotonin/violence hypothesis has not been assessed at the epidemiological level. For study of an epidemiological sample we examined blood serotonin, because certain physiological and behavioral findings suggested that it might serve as an analog marker for serotonergic function.

METHODS

Whole blood serotonin was measured in a representative birth cohort of 781 21-year-old women (47%) and men (53%). Violence was measured using cumulative court conviction records and participants' self-reports. Potential intervening factors addressed were: gender, age, diurnal variation, diet, psychiatric medications, illicit drug history, season of phlebotomy, plasma tryptophan, platelet count, body mass, suicide attempts, psychiatric diagnoses, alcohol, tobacco, socioeconomic status, IQ, and overall criminal offending.

RESULTS

Whole blood serotonin related to violence among men but not women. Violent men's mean blood serotonin level was 0.48 SD above the male population norm and 0.56 SD above the mean of nonviolent men. The finding was specific to violence, as opposed to general crime, and it was robust across two different methods of measuring violence. Together, the intervening variables accounted for 25% of the relation between blood serotonin and violence.

CONCLUSIONS

To our knowledge, this is the first demonstration that an index of serotonergic function is related to violence in the general population.

The role of Na-K-activated adenosine triphosphatase in potassium adaptation. Stimulation of enzymatic activity by potassium loading

The specific activity of sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) in homogenates of rat kidneys increases when the dietary intake of potassium is chronically increased. The effect is seen first and is most prominent in the outer medulla, but large loads of potassium elicit an increase in the cortex as well. Levels of Na-K-ATPase in brian, liver, and muscle, by contrast, are unaffected by potassium loading. Although the changes in enzyme activity in the kidney resemble those reportedly produced by aldosterone, they are not induced by experimental sodium deprivation, and they can be evoked by potassium loading in the absence of the adrenal glands. The results suggest that Na-K-ATPase of renal tubular cells, presumably in the distal tubules and collecting ducts, plays an important role in the phenomenon of potassium adaptation and in the process by which potassium is excreted into the urine.

Mechanism of active chloride secretion by shark rectal gland: role of Na-K-ATPase in chloride transport

The isolated rectal gland of Squalus acanthias was stimulated to secrete chloride against an electrical and a chemical gradient when perfused in vitro by theophylline and/or dibutyryl cyclic AMP. Chloride secretion was depressed by ouabain which inhibits Na-K-ATPase. Thiocyanate and furosemide also inhibited chloride secretion but ethoxzolamide, a carbonic anhydrase inhibitor, did not. Chloride transport was highly dependent on sodium concentration in the perfusate. The intracellular concentration of chloride averaged 70-80 meq/liter in intact glands, exceeding the level expected at electrochemical equilibrium and suggesting active transport of chloride into the cell. These features suggest a tentative hypothesis for chloride secretion by the rectal gland in which the uphill transport of chloride into the cytoplasm is coupled through a membrane carrier to the downhill movement of sodium along its electrochemical gradient. The latter is maintained by the Na-K-ATPase pump while chloride is extruded into the duct by electrical forces.

Impairment of extrarenal potassium disposal by alpha-adrenergic stimulation

Since beta-adrenergic stimulation enhances extrarenal potassium uptake, we postulated an opposite effect of the alpha-adrenergic nervous system. Seven healthy subjects were given intravenous potassium chloride (0.5 mmol per kilogram of body weight), in the presence and absence of the alpha-agonist phenylephrine. After potassium chloride alone, the potassium level rose to 0.64 +/- 0.03 mmol (mean +/- S.E.M.); phenylephrine augmented the rise (0.93 +/- 0.09 mmol, P less than 0.025) and prolonged it, without changing urinary potassium excretion. Subsequent administration of potassium and phenylephrine together with the alpha-antagonist phentolamine blocked the rise in the potassium level due to phenylephrine and shortened the duration of elevation, again without affecting urinary potassium excretion. No changes in plasma renin and aldosterone levels or in serum insulin concentrations occurred, to account for these findings. Stimulation of alpha-adrenergic receptors impairs extrarenal disposal of an acute potassium load--the opposite effect of beta-adrenergic stimulation. The alpha-adrenergic effect may act to preserve a normal serum potassium level or may contribute to hyperkalemia under certain circumstances, such as vigorous exercise.

Cognitive and social correlates of DSM-III disorders in preadolescent children

The relationships between some cognitive and social measures and the major syndromes found in a large preadolescent sample of children from the general population are described. The measures discriminated between disorder-no disorder for most variables examined and between the broad groups of externalizing and internalizing disorders, but not between individual diagnostic categories. An important exception was that ADDH and conduct disorder occurring as single disorders could be distinguished, but the frequent comorbidity of these and other disorders complicated many between-group comparisons.