Endogenous creatinine in serum and urine

Predisposition to hypertension and susceptibility to renal disease in insulin-dependent diabetes mellitus

Only one third of patients with juvenile-onset insulin-dependent diabetes seem to be susceptible to diabetic nephropathy. To test whether this susceptibility is related to a predisposition to hypertension, we investigated the association of nephropathy with markers of risk for hypertension. We randomly selected 89 patients with insulin-dependent diabetes from a roster of children and adolescents who were seen between 1968 and 1972 at about the time the diagnosis was made. These 89 patients were recalled for examination, as young adults, in 1986 and 1987. Patients with nephropathy (cases, n = 33) were compared with controls without nephropathy (n = 56). Having a parent with hypertension tripled the risk of nephropathy (odds ratio, 3.7; 95 percent confidence interval, 1.4 to 10.1). Moreover, cases had significantly higher values for maximal velocity of lithium-sodium countertransport in red cells than controls (mean maximal velocity +/- SE, 0.51 +/- 0.04 vs. 0.38 +/- 0.02 mmol per liter of cells per hour; P less than 0.05). The excess risk associated with both these indicators of a predisposition to hypertension was evident principally in patients with poor glycemic control during their first decade of diabetes; the odds ratios were 4.5 (95 percent confidence interval, 1.1 to 18.7) for patients with a parental history of hypertension and 7.7 (95 percent confidence interval, 1.8 to 33.8) for patients with a maximal velocity of lithium-sodium countertransport greater than or equal to 0.35 mmol per liter of cells per hour. We conclude that the risk of renal disease in patients with juvenile-onset insulin-dependent diabetes is associated with a genetic predisposition to hypertension. Predisposition to hypertension appears to increase susceptibility for renal disease principally in patients with poor glycemic control.

Resistance to acute nephrotoxicity induced by cadmium-metallothionein dependence on pretreatment with cadmium chloride

Three groups of rats (B-D) were given various daily doses of CdCl2 (0.5-2 mg Cd/kg) continuously or in intervals during time periods of 1-8 weeks. Another group of animals (A) were kept untreated. At the end of the period, selected subgroups of groups A-D were given a single subcutaneous injection of 109Cd-metallothionein (109CdMT) 0.05 or 0.4 mg Cd/kg ("challenge dose"). Subsequently, urinary creatinine, protein, Cd, 109Cd and MT and kidney cortex Cd, 109Cd and MT were determined. In group A (no long term pretreatment), an increased proteinuria was observed after the rats had received the lower of the challenge doses of 109CdMT, and an even greater increase after the higher challenge dose of 109CdMT. No such increase appeared in group B, C and D (repeatedly pretreated with CdCl2) at either of the challenge doses. Higher metallothionein concentrations in kidney cortex observed in the pretreated groups constitute a plausible explanation of the protective effects of pretreatment against the development of increased proteinuria after challenge dosing. It is likely that increasing Cd concentrations, gradually accumulating in the renal cortex (22-226 micrograms/g wet wt.) as a result of the pretreatment, served to induce the synthesis of metallothionein in the renal cortical cells, thus making them resistant to the challenge from 109CdMT.

Evaluation of a parathyroid hormone antagonist in an in vivo multiparameter bioassay

The antagonist properties of a bovine parathyroid hormone analogue ([Tyr34]bPTH-(7-34] amide were quantitatively assessed in vivo in a multiparameter assay to estimate the potency of the antagonist against the major actions of PTH. The analogue inhibited PTH-stimulated urinary excretion of phosphate and adenosine 3',5'-cyclic monophosphate in vitamin D-deficient thyroparathyroidectomized rats in a dose-dependent manner. At a molar dose ratio as low as 5:1 of antagonist to PTH, partial inhibition occurred. PTH stimulates the activity of 25-hydroxyvitamin D3-1 alpha-hydroxylase in renal proximal tubules. When coinfused with PTH, this analogue completely inhibited PTH-stimulated 1 alpha-hydroxylase activity at a molar dose ratio of 25:1 of antagonist to PTH and partially inhibited the activity at a molar dose ratio of 10:1. The analogue revealed no PTH-like agonist activity for stimulation of the 1 alpha-hydroxylase. Taken together, these studies indicate that [Tyr34]bPTH-(7-34) amide is a potent antagonist of several of the parameters of PTH action in vivo and demonstrate the feasibility of designing a PTH antagonist that can interact simultaneously with all the PTH receptors responsible for the hormone's major actions in vivo.

Influence of cadmium-metallothionein pretreatment on tolerance of rat kidney cortical cells to cadmium toxicity in vitro and in vivo

Kidney cells were isolated from rats pretreated by daily subcutaneous doses of cadmium metallothionein (CdMT: 0.05-0.2 mg Cd/kg X 5) and from non-pretreated rats. Upon exposure to CdCl2 in vitro (0-200 micrograms Cd/ml), a concentration dependent decrease in viability was observed in the non-pretreated cells, while no such decrease occurred in the pretreated cells indicating that these cells were more resistant to the toxic action of cadmium. There was a higher in vitro uptake of Cd+2 and an increased metallothionein (MT) concentration in the pretreated cells (compared to non-pretreated cells). Subcellular distribution studies revealed that Cd was mainly recovered in the "cytosol" fraction. The higher total cadmium uptake in pretreated cells corresponded to an increase of Cd in "cytosol" and "nuclear" fractions. This observation may be explained by MT-binding of Cd in the cells and is in accordance with a possible protective effect of induced MT in the pretreated cells. In order to assess whether pretreatment-induced tolerance to cadmium toxicity--indicated by the cellular studies--could also be observed in vivo, some whole animal experiments were also performed. A dose-related proteinuria was observed in non-pretreated rats after a single subcutaneous administration of 109Cd-MT at doses of 0.05 and 0.4 mg Cd/kg. Urinary total Cd, 109Cd and MT was also increased in a dose-related fashion. Cadmium concentrations in kidney were dose related and reached 19 micrograms/g wet weight. In contrast, in animals repeatedly pretreated with CdMT according to 1), no proteinuria was observed after administration of the same single doses of 109CdMT. Total Cd. 109Cd and particularly MT-concentrations in urine were lower in such pretreated animals than in in non-pretreated ones in spite of the accumulation of higher tissue concentrations of total Cd (up to 80 micrograms/g). The pretreatment was thus shown to prevent some of the acute nephrotoxicity of CdMT, possibly by means of induction of MT synthesis.

Kidney immunopathology and pathophysiology in rats immunized with proximal tubule cell brush border or basolateral membrane vesicles

Proximal tubule pathology in Heymann nephritis has been attributed to anti-brush border antibodies, but antibodies with other specificities might also be important. To determine whether injury to the basolateral membranes of proximal tubules could occur independently of brush border injury, LEW rats were immunized either with partially purified basolateral or brush border membrane vesicles. Both immunogens produced glomerular immunopathology and pathophysiology identical in magnitude and time course to that seen in Heymann nephritis. Antibodies eluted from the kidneys of rats immunized with either antigen preparation stained the brush border in vitro. However, circulating anti-brush border antibodies were in significant titers only in rats immunized with brush border vesicles, whereas antibodies that stained the cytoplasm of both proximal and distal tubules predominated in rats immunized with basolateral membranes. With the onset of proteinuria, rats immunized with brush border membranes developed the proximal tubule pathology of Heymann nephritis. In rats immunized with basolateral membranes, the brush border and apical aspect of proximal tubule cells remained essentially normal. However, defects of basolateral membrane transport function were present, indicating that those defects need not necessarily be secondary to brush border damage. The dissociation of brush border damage from glomerular injury suggests that different antibody populations may account for each. Furthermore, anti-brush border antibodies may not account for all aspects of proximal tubule pathology in Heymann nephritis.

Tubulo-interstitial lesions mediate renal damage in adriamycin glomerulopathy

The present study was designed to investigate the relationship between proteinuria, focal sclerosis, and tubulo-interstitial changes in the evolution of renal damage in experimental nephrosis. We utilized an accelerated unilateral model of adriamycin (ADR) nephrosis characterized by morphological changes more severe than in the classical model. The first events in ADR-induced glomerulopathy were epithelial cell damage and proteinuria. Subsequently, tubular casts were formed at the distal level. The cast formation preceded the development of interstitial damage, which was determined by tubular obstruction and breaking of tubular basement membrane (TBM), which in turn promoted an interstitial inflammatory reaction. Despite the severity of tubulo-interstitial damage observed after a long period of heavy proteinuria, the incidence of focal segmental glomerulosclerosis (FSG) was very low. The results of the present study indicate that chronic proteinuria is not necessarily accompanied by the development of focal sclerosis. Tubulo-interstitial lesions appear to be the most important determinant for the progression of renal damage in this model.

A transition from proliferative to membranous glomerulonephritis in chronic serum sickness

Chronic serum sickness glomerulonephritis was induced in rats by daily i.v. administration of bovine serum albumin (BSA). Previous studies have shown that the disease progresses through three discrete stages: mild, moderate and severe. The diffuse, proliferative necrotizing glomerulonephritis of severe chronic serum sickness, which is accompanied by a decreased glomerular filtration rate and increased glomerular permeability to macromolecules, has an inevitable fatal outcome. In the experiments reported here, BSA injections were discontinued at the transition from moderate to severe glomerulonephritis, a point which was identified by decreased sodium excretion. Retrospectively, rats could be divided into two categories. Some, called non-survivors, continued to exhibit sodium retention. Those animals progressed rapidly to end-stage renal disease and died within two weeks of the cessation of antigen injections. Others, called survivors, returned to sodium balance and remained alive for many months. The development of progressive membranous glomerulonephritis, with prominent spike formation and disappearance of glomerular hypercellularity, was noted in all survivors. That change in histopathology occurred in the absence of both circulating BSA and precipitating antibodies to BSA. The transition of proliferative to membranous glomerulonephritis was accompanied by partial recovery of glomerular function, although proteinuria persisted. Maintenance of severe proteinuria did not appear to depend on an active immunological process.

Airborne arsenic and urinary excretion of metabolites of inorganic arsenic among smelter workers

The relationship between airborne concentrations of arsenic and the urinary excretion of inorganic arsenic metabolites (inorganic arsenic + methylarsonic acid + dimethylarsinic acid) have been studied among smelter workers exposed to arsenic trioxide. The urinary concentrations of arsenic metabolites were found to increase steadily during the first day of the working week (after 2-3 d off from work), whereafter they reached a steady state. The concentration in the late evening after a day of exposure was very similar to that in the early morning after. Both were well correlated to the total daily excretion. In the second part of the study, comprising 18 subjects, the first-void morning urine of each participant was collected for 2 to 3 d during the steady-state phase. Total concentration of arsenic in the breathing zones was measured by personal air samplers. Airborne arsenic (8-h values) varied between 1 and 194 micrograms As/m3, and urinary arsenic between 16 and 328 micrograms As/g creatinine. With the urinary arsenic concentrations (mean values of 2-3 d for each subject) plotted against the corresponding airborne arsenic concentrations, the best fit was obtained by a power curve with the equation y = 17 X X0.56. However, four of the participants were found to excrete far more (105-260%) arsenic in the urine than possibly could have been inhaled, most likely due to oral intake of arsenic via contaminated hands, cigarettes or snuff. If these four were excluded, the best fit was obtained by a straight regression line with the slope 2.0 and the intercept 29 micrograms As/g creatinine (coefficient of correlation 0.92; P less than 0.001).

Mechanism of urinary kallikrein excretion and its action on water excretion

In male Wistar rats urinary kallikrein excretion was positively correlated with urinary flow and glomerular filtration rate and negatively with urinary osmolality and with TcH2O. The mechanism of urinary kallikrein excretion is interpreted as a wash-out effect of renal kallikrein. The renal kallikrein regulates the water excretion decreasing the reabsorption of water in the distal nephron.

Pathophysiology of the kidney in rats with Heymann nephritis

Alterations in kidney function were assessed early in the course of Heymann nephritis that was induced in rats by immunization with Fx1A, an extract prepared from rat kidney cortex. Whole kidney and single nephron function were evaluated by clearance and micropuncture techniques. Kidney function was studied in stage 1 of Heymann nephritis, before the onset of proteinuria, and in stage 2, when antibodies are deposited along the brush border of proximal tubules. Although overall kidney function was similar in rats in stage 1 and normal controls, glucose reabsorption was somewhat depressed in the first part of the proximal convoluted tubule in stage 1. Both whole kidney and single nephron glomerular filtration rates were depressed in stage 2. Proteinuria in stage 2 was characterized by an increased albumin sieving coefficient, which resulted in an elevated excretion of albumin. Furthermore, several proximal tubule functions (glucose and fluid reabsorption and PAH extraction) were substantially depressed in stage 2. These findings demonstrate that immunological injury to the proximal tubules in stage 2 of Heymann nephritis produces a significant impairment of proximal function.

High-pressure liquid chromatographic methods for determining arabinosyladenine-5'-monophosphate, arabinosyladenine, and arabinosylhypoxanthine in plasma and urine

New high-pressure liquid chromatographic methods for determining concentrations of arabinosyladenine (Ara-A), its 5'-monophosphate (Ara-AMP), and arabinosylhypoxanthine (Ara-H) in plasma and urine are presented. A fluorescence detector is used for Ara-A and Ara-AMP, which are first converted to highly fluorescent derivatives with chloroacetaldehyde. This increases sensitivity greatly over previous methods. The sensitivities of the methods (in micrograms per milliliter) are as follows: in plasma, Ara-AMP, 0.002; Ara-A, 0.0015; and Ara-H, 0.35; and in urine, 9 times these values, respectively. Drug concentration data are also presented, which were obtained after doses of Ara-AMP were given intramuscularly to two patients treated with this drug for severe herpes zoster. One patient was given 13 mg of Ara-AMP per kg of body weight once daily, and the other was given 6.5 mg/kg twice daily. Peak Ara-AMP and Ara-A levels in plasma occurred within 1 h after the doses, and neither exceeded 2 micrograms/ml. Ara-AMP and Ara-A concentrations in plasma fell to less than 0.01 micrograms/ml in both patients by 4 to 6 h after the doses. Peak Ara-H concentrations in plasma occurred within 1 to 2 h after doses and were 21 micrograms/ml in patient 1 and 2. The highest concentration of Ara-AMP in urine was 0.09 micrograms/ml. The highest Ara-A concentration in urine was 62 micrograms/ml, and the highest Ara-H concentration in urine was 1,080 micrograms/ml. An interfering substance of unknown nature, cochromatographing with Ara-H, was encountered sporadically in urine samples. An algorithm based on differential spectrophotometry to identify and correct for this problem is described. Estimates of the renal clearances of Ara-AMP, Ara-A, and Ara-H are also given.

Low-protein diet prevents glomerular damage in adriamycin-treated rats

Adriamycin (ADR) induces glomerular damage in rats with persistent proteinuria which develops 13 to 15 days after a single intravenous (i.v.) injection (5 mg/kg). Electron microscopy (EM) shows alterations of glomerular visceral epithelial cells with foot process fusions. The disease resembles minimal change nephropathy in humans. We studied the effect of two isocaloric diets with different protein content on urinary protein excretion, renal function, and glomerular morphology in rats treated with ADR. Six groups of rats were used. Group 1 received a single i.v. injection of ADR and was fed a standard diet containing 20% protein. Group 2 was fed a low-protein diet containing 6% protein starting 7 days before ADR. Group 3 was fed a low-protein diet starting the day after ADR. Group 4 served as control. Two additional groups of rats (5 and 6) were used to study the kidney distribution of ADR. Unlike animals fed the standard diet, animals fed the low-protein diet did not develop proteinuria. The kidney distribution of ADR measured at different intervals after drug injection was not influenced by the diet. Renal function as determined by glomerular filtration rate (GFR) and renal plasma flow (RPF) was not significantly modified in nephrotic rats receiving the standard diet compared to control animals. The low-protein regimen induced a significant elevation in RPF compared to the standard diet, but had no influence on GFR. Light and transmission EM studies showed alterations of glomerular visceral epithelial cells with fusion of foot processes in rats fed the standard diet, whereas no significant abnormalities of glomerular epithelial cells were detectable in animals receiving the low-protein diet.(ABSTRACT TRUNCATED AT 250 WORDS)

A double blind trial of dipyridamole in CAPD

Since we had previously shown that dipyridamole augmented inulin and glucose clearance during intermittent peritoneal dialysis we sought to extend our study to the patient undergoing continuous ambulatory peritoneal dialysis. We carried out a double blind study in which patients received either 75 mg of active drug or placebo for a 2-week period. At the end of this period the mass transfer coefficients, between plasma and dialysate, were measured for selected solutes. We did not find any drug effect. The results of our first study together with the results of this study suggest that dipyridamole has no place in the chronic management of patients undergoing peritoneal dialysis.

Longitudinal studies on the rate of decline in renal function with age

Serial creatinine clearances (5 to 14 studies) were obtained for 446 normal volunteers in the Baltimore Longitudinal Study of Aging followed between 1958 and 1981. When those subjects with possible renal or urinary tract disease and subjects on diuretics and antihypertensives were removed from the study, leaving a group of 254 "normal" subjects, the mean decrease in creatinine clearance was 0.75 ml/min/year. The slopes of the creatinine clearance vs. time fell into a normal (Gaussian) distribution around this mean. One third of all subjects followed had no absolute decrease in renal function (positive slope of creatinine clearance vs. time) and there was a small group of patients who showed a statistically significant increase (P less than 0.05) in creatinine clearance with age.

Increased urine volume in chronic schizophrenic patients

Polydipsia and polyuria have a long association with schizophrenia. To assess the prevalence of polydipsia and polyuria in schizophrenia, urine volume was examined in medication-free chronic schizophrenic patients, normal controls, and nonschizophrenic patients. Mean urine volume was significantly higher in the schizophrenic patients (2319 +/- SD 2052 ml/24 hours) than in the other two groups (1054 +/- SD 471 ml/24 hours for nonschizophrenic patients and 1265 +/- SD 613 ml/24 hours for normals). Seven of 35 patients with schizophrenia but 0/7 nonschizophrenics had urine volumes greater than any normal control. Polyuria was associated with a good premorbid history and a positive neuroleptic response. Among polyuric patients, those with hyponatremia may represent a different, distinct subgroup. Neuroleptic treatment was associated with a further, significant increase in urine volume. Hence, polydipsia and polyuria appear to be relatively common in schizophrenia.

Increased glomerular thromboxane synthesis as a possible cause of proteinuria in experimental nephrosis

Altered glomerular metabolism of arachidonic acid (AA) has already been demonstrated in experimental nephrotoxic nephritis. The enhanced synthesis of thromboxane A2 (TxA2) in isolated glomeruli that has been found may mediate changes in renal hemodynamics. The objectives of this investigation were: to check whether glomerular AA metabolism is also altered in a model of glomerulopathy in which no leukocyte infiltration or platelet deposition could be demonstrated; to establish a correlation between the altered AA metabolism and proteinuria; and to explore whether the alteration of the prostaglandin (PG) pathway found in isolated glomeruli is an in vitro artifact or reflects a modification in vivo. We used a model of glomerular damage characterized by heavy and persistent proteinuria, which was induced in the rat by a single intravenous injection of adriamycin. At light microscopy, minimal glomerular abnormalities were found in this model. Electron microscopy showed profound alterations of glomerular epithelial cells with extensive fusion of foot processes and signs of epithelial cell activation. Electron microscopy of numerous glomeruli showed no platelet deposition or macrophage and leukocyte infiltration in this model. Isolated glomeruli from nephrotic rats studied 14 or 30 d after a single intravenous injection of adriamycin (7.5 mg/kg) when animals were heavily proteinuric generated significantly more TxB2, the stable breakdown product of TxA2, than normal glomeruli. No significant changes were found in the other major AA metabolites formed through cyclooxygenase. Urinary excretion of immunoreactive TxB2 was also significantly higher in nephrotic than in normal animals. Administration of a selective Tx synthetase inhibitor, UK-38,485, from day 14 to day 18 after adriamycin resulted in a significant reduction of proteinuria compared with pretreatment values. Glomerular synthesis and urinary excretion of TxB2 were normal during the UK-38,485 treatment. Additional experiments showed that elevated glomerular synthesis and urinary excretion of TxB2 were not a consequence of increased substrate availability. Maximal stimulation of the renin-angiotensin axis with furosemide increased glomerular TxB2 synthesis in normal rats, which was significantly lower than in nephrotic animals. Finally, experiments using a unilateral model of adriamycin nephrosis indicated that the enhancement of glomerular TxB2 synthesis is not simply a consequence of the nephrotic syndrome. We conclude that: there is an abnormality of glomerular AA metabolism in nephritic syndrome, which leads to increased TxA2 production; the increased Tx generation correlates with protein excretion and might be responsible for altering the glomerular basement membrane permeability to protein; and the alteration found in isolated glomeruli probably reflects a modification in vivo, in that urinary excretion of immunoreactive TxB2 is also consistently increased in adriamycin nephrosis.

Association between blood pressure and the rate of decline in renal function with age

A significant negative correlation (P less than 0.0001) exists between the mean blood pressure (MBP) and the rate of decline in creatinine clearance with time in years (BCr) in 446 subjects in the Baltimore Longitudinal Study on Aging (BLSA) followed serially on five or more visits over a period of 8 or more years. Even when the 118 subjects with possible renal and/or urinary tract pathology (category 1) and 74 subjects treated with diuretic and/or antihypertensive agents (category 2) were not included, this relationship remained in the 254 "normal" (category 3) subjects. Since both MBP and negativity of the BCr tend to increase with age, multiple regression analyses using both MBP and age as independent variables were performed to determine their respective influences on BCr. Both MBP and age significantly influenced BCr. When those subjects with hypertension (mean MBP greater than 107 mm Hg) were not included, however, the inverse relationship between MBP and BCr is lost, suggesting that an accelerated loss of renal function is observed primarily because of the impact exerted by individuals with blood pressures in the hypertensive range.

The effect of neonatal hyperbilirubinemia on the measurement of plasma creatinine

Bilirubin interferes with the measurement of plasma creatinine by the kinetic colorimetric Jaffe reaction, the method currently used by many hospital laboratories. The purpose of the present study was to evaluate the influence of unconjugated bilirubin on the measurement of plasma creatinine by the AutoAnalyzer Jaffe end point method. This colorimetric method is slower but more precise and accurate in the range of 0.25 to 0.5 mg/dl. We found that bilirubin from jaundiced neonates and from stock solutions did not affect the determination of creatinine chromogen in plasma or in saline, even at concentrations as high as 25 mg/dl. We conclude that the use of the Jaffe end point AutoAnalyzer method with a blank run before each sample will provide an accurate measurement of creatinine in the plasma of the neonate with unconjugated hyperbilirubinemia.

Relationship of kidney function to immunopathology in chronic serum sickness of rats

This study sought to clarify the relationship between kidney function and immunopathology in chronic serum sickness (CSS) of rats. CSS was induced by chronic intravenous immunization with bovine serum albumin. Whole kidney function was studied during the course of CSS by assays of serum and urine. Single nephron function was evaluated by micropuncture techniques. Three categories (mild, moderate, severe) of kidney disease were identified from the analysis of kidney function in rats with CSS. Those categories represented distinct stages in the natural history of CSS nephritis. The three stages identified by measurements of function corresponded to distinct categories of kidney immunopathology. In rats with milk CSS, immune deposits were limited to the mesangium; histopathology was slight or absent. The only detectable change in protein handling was a small elevation of albumin concentration in tubule fluid. Abnormal proteinuria was a feature of moderate CSS; whole kidney glomerular filtration was not decreased despite evidence of significant immunopathology of glomeruli. Compromise of whole kidney function including decreased sodium excretion was only detected in the severe stage of CSS in association with diffuse proliferative glomerulonephritis. The transitions from mild to moderate and moderate to severe CSS were not gradual but occurred as discrete, sudden events.

A multiresponse parathyroid hormone assay: an inhibitor has agonist properties in vivo

Vitamin D-deficient rats subjected to thyroparathyroidectomy (TPTX) were used to evaluate in vivo the biological properties of native bovine parathyroid hormone (bPTH) and chemically synthesized fragments and analogues of the hormone on several parameters of hormone action: calcium and phosphorus fluxes, generation of cyclic adenosine 3',5'-monophosphate (cAMP), and the metabolism of 25-hydroxyvitamin D3 [25(OH)D3]. Vitamin D-deficient rats, after TPTX or sham operation, were intravenously infused with a nutrient containing 7.5 mM CaCl2 for 30 h. During the last 7 h, PTH or one of its analogues was infused intravenously at rates between 0.04 and 20 nmol/h. One hour after the start of the peptide infusion, tritiated 25(OH)D3 was injected. Urine was collected hourly for phosphate and cAMP determinations and, at the end of the experiment, blood was obtained to determine the relative accumulation of tritiated 1,25-dihydroxyvitamin D3 ([3H]1,25(OH)2D3). Infusion of bPTH-(1--84), bPTH-(1--34), human (h)PTH-(1--34), or [Nle8, Nle18, Tyr34]bPTH-(1--34) amide was accompanied by a comparable dose-dependent decrease in plasma phosphate and a dose-dependent increase in plasma calcium and [3H]-1,25(OH)2D3, and urinary excretion of phosphate and cAMP. An evaluation of [Nle8, Nle18, Tyr34]bPTH-(3--34) amide, a potent inhibitor of PTH action in vitro in the renal adenylate cyclase assay, revealed that the analogue possessed weak agonist properties in vivo. The analogue increased excretion of both cAMP and phosphate in the urine, decreased plasma phosphate levels, and increased the accumulation of [3H]-1,25(OH)2D3 in the plasma. This multiparameter model system should aid in the elucidation of the in vivo biological effects of PTH and its analogues.

Gas-liquid chromatography reference method for the assay of urinary creatinine

The gas-liquid chromatographic measurement of urinary creatinine described in this paper employs methylation, the use of a diethylene glycol succinate stationary phase, an internal L-hydroxyproline standard and a temperature of 180 degrees C. The technique, which is specific and reproducible, is shown to be a reference method providing more precise and reliable results than a conventional colorimetric method. In addition, it can be used as a routine method because of its simplicity.

Comparison of home hemodialysis to continuous ambulatory peritoneal dialysis

We evaluated prospectively various outcome measurements of patients assigned initially to continuous ambulatory peritoneal dialysis (CAPD) and home hemodialysis (HHD) from February 1979 to August 1981 and the causes for failures of the techniques. Morbidity was assessed by time in hospital/time on dialysis. Fifty-six patients were trained for CAPD and 37 for HHD. Those assigned to CAPD experienced an increased frequency of hospitalization (7.5% CAPD, 2.8% HHD, respectively) primarily due to episodes of peritonitis. There was also a higher modality failure rate (43% vs. 16%). However, the groups were not comparable in all respects. For example, the CAPD population included 21 patients with major cardiovascular diseases versus only three in the HHD group. The demographic characteristics of both populations including race, sex, age, income, place of residence, marital status, and education were similar. At the time of this study there is no direct evidence showing that healthy patients otherwise able to perform HHD may be maintained with less morbidity for a prolonged period utilizing CAPD. Therefore, we suggest that HHD is the home method of choice for patients able to proceed with this technique. CAPD may be indicated for patients in whom the period of home dialysis is expected to be relatively short and who would be otherwise unable to carry out home dialysis, for example, patients awaiting transplantation and those unable to be maintained on hemodialysis because of impaired cardiac function. To fully evaluate CAPD as a long-term maintenance therapy, a prospective trial must be performed.

Augmentation of peritoneal clearance by dipyridamole

We performed a double blind crossover trial in which dipyridamole was administered to ten patients undergoing intermittent peritoneal dialysis at 2 liters/hour (10 min infusion, 30 min intraperitoneal dwell of dialysate and 20 min drainage of dialysate). After the patients received the drug for 3 days at a dose of 75 mg three times daily, peritoneal inulin clearance increased by 1.2 ml/min (P less than 0.05), and glucose absorption increased by 12.1 g (P less than 0.05). The mechanism of the observed drug-induced effects is unknown.

In vitro studies on an antagonist of parathyroid hormone [Nle-8, Nle-18, Tyr-34]bPTH-(3-34)amide

1 The actions of parathyroid hormone (PTH) are antagonized in vitro by the peptide [Nle-8, Nle-18, Tyr-34]-bPTH-(3-34)amide, an analogue of PTH. In this paper, the actions of the inhibitory peptide were investigated in vivo. 2 Native parathyroid hormone (bPTH-(1-84)), administered i.v. (0.17-1.51 nmol in volume of 0.3 ml) to 7 day old chicks produced hypercalcaemia but administration of the analogue in doses up to 173 nmol was ineffective in this respect. 3 The analogue failed to antagonize the hypercalcaemia produced by bPTH-(1-34) when injected, in 10 fold molar excess, 2 min before or simultaneously with bPTH-(1-34). 4 Normocalcaemia was restored in parathyroidectomized rats by intravenous infusion of bPTH-(1-84) at 32 pmol kg-1 h-1. Addition of the analogue to the infusion fluid in a 200 fold molar excess did not affect the concentrations of calcium and phosphate in the plasma, cyclic adenosine 3',5'-monophosphate (cyclic AMP) in the urine or phosphate clearance but produced a significant (P less than 0.05) rise in urinary calcium clearance. 5 The results suggest that the peptide [Nle-8, Nle-18, Tyr-34]-bPTH-(3-34)amide does not antagonize the actions of PTH in vivo and demonstrate an important dichotomy between in vitro and in vivo biological properties of the PTH analogue.

Cross-cultural study of a biochemical abnormality in paranoid schizophrenia

We studied 24-hour urinary excretion of phenylethylamine (PEA) and creatinine in 50 schizophrenic (39 paranoid and 11 nonparanoid) and 19 nonpsychiatric patients from Bombay, India. Methods for diagnosis, clinical assessment, and 24-hour urine collection were identical to those used in an earlier study done in a Washington, D.C. hospital. Clinical evaluations were done in Bombay, while urinary PEA and creatinine estimations were performed at NIMH, Washington, without knowledge of the subjects' identify. Paranoid schizophrenic patients had significantly greater 24-hour urinary excretion of PEA than both nonparanoid schizophrenic patients and nonpsychiatric controls. The mean amount of PEA per g creatinine in urine was also highest of paranoid schizophrenic patients. Our findings provide cross-cultural support to the possibility of abnormal PEA metabolism in at least some patients with paranoid schizophrenia.

Renal lesions and proteinuria in the spontaneously hypertensive rat made normotensive by treatment

Spontaneously hypertensive rats (SHR) (N = 40) were maintained at normal blood pressure to the age of 100 weeks by treatment (reserpine, hydralazine, and chlorothiazide) beginning at intervals in groups of eight, from the 5th to 45th week. Mortality rates, patterns of proteinuria, and glomerular and arteriolar pathology were compared with that of treated and untreated normotensive Wistar-Kyoto (WKY) controls matched for age (N = 39) and untreated SHR's (N = 26). Treatment clearly prolongs life in SHR's, the mortality rate for untreated being 100% at 75 weeks versus no deaths at that age among 24 SHR's treated before 20th week. At 100 weeks, treated SHR's were excreting eight times the baseline values of urinary protein, whereas WKY's had hardly increased from baseline values. At 100 weeks, normotensive SHR's showed fibrinoid necrosis, sclerosis, and pericapsular fibrosis of glomeruli, whereas no morphologic damage was found in glomeruli or renal arterioles of WKY. Glomerular lesions in normotensive SHR's are indistinguishable in kind from their hypertensive counterparts, but occur somewhat later. Juxtamedullary glomeruli initially suffer the greatest damage and appear to be the major source of urinary protein. These findings speak against the hypothesis of an increased intravascular pressure as the major factor in the pathogenesis of arteriolar sclerosis and rather favor a genetic defect in the vascular system of the SHR, a defect strongly associated with the hypertensive trait. A possible relationship of this defect to inherited membrane abnormalities recently described in RBC and smooth muscle cells of SHR is discussed.

Beta 2-microglobulin levels in serum and urine of cadmium exposed rabbits

Male rabbits were exposed to cadmium during 16 weeks by subcutaneous injections of either 0.25 mg or 0.5 md Cd as cadmium chloride per kg body weight 3 times per week. beta 2-microglobulin (beta 2-m) and creatinine in serum, cadmium in blood, as well as total protein, creatinine, beta 2-m and cadmium in urine were determined before exposure and after 3 and 7 weeks of exposure. Measurements were also made at 19 weeks, 3 weeks after the last exposure. During exposure, there was a slight increase in the serum beta 2-m/creatinine ratio among rabbits with the highest exposure, while no effect of the cadmium burden could be observed once exposure had ceased. Urinary excretion of beta 2-m was related to urinary pH, which appeared to be the case also for excretion of total protein. In the high exposure group, a significant increase in urinary beta 2-m excretion, indicative of renal tubular dysfunction was seen after 7 weeks of exposure. This was, however, not related to serum beta 2-m levels. It was concluded that before renal damage has occurred even heavy cadmium exposure has very little influence on serum beta 2-m levels.

Urinary electrolytes, body weight, and blood pressure. Pooled cross-sectional results among four groups of adolescent females

Results of blood pressures (BP) and urinary electrolyte excretion studies are reported among several groups of adolescent and young adult females, both black and white, who were initially examined in high school and restudied at home 3--4 years later. Pooling of the data from the several cross-sectional studies (n = 662) revealed a weak but statistically significant positive correlation systolic blood pressure (SBP) and the urinary sodium (Na) excretion rate. Three of four correlations between SBP and potassium (K) were of an inverse nature. Although not statistically significant in their own right, when coupled with the Na/K excretion ratio, which was significantly associated with SBP, a moderating role for K is suggested. The urinary Na, K, and creatinine (Cr) excretion rates were highly intercorrelated and were correlated with weight. As measured by R2 in a stepwise regression analysis, weight contributed approximately 3% to the BP variance, and the urinary electrolytes accounted for approximately 2% of the SBP variance. Statistically significant partial correlation coefficients between SBP and Na, and Na/K, remained after adjusting for body weight.

Changes in plasma urate, creatinine, alkaline phosphatase and the 24 hours excretion of hydroxyproline during sexual maturation in adolescents

The relative concentrations of plasma uric acid and creatinine, the alkaline phosphatase activities and the 24 hour urinary excretion of hydroxyproline together with sexual maturity ratings are reported in a population of normal British schoolchildren studied longitudinally over a three-year period. The children were all of European origin and their ages ranged from 7 to 17 years. Plasma urate rose sharply during puberty in the boys but not in the girls. Plasma creatinine rose in both sexes during maturation. Plasma alkaline phosphatase activity rose to a peak at genital maturity 3(G3) in boys and breast maturity 2(B2) in girls and subsequently fell rapidly in both sexes. The 24-hour urinary secretion of hydroxyproline was high in young boys and rose to a peak during G3 and G4 and then fell rapidly. In girls there was no significant peak in concentrations, although there was a fall during B4 and B5, and levels were higher throughout puberty than those reported for adult females.

Metabolic aspects of bone resorption in calcium-deficient lactating rats

Lactating female rats were fed diets containing 1.0, 0.1, or 0.04% Ca for 21 days. Fat-free dry weight, ash weight, calcium and phosphorus content of the humerus, plasma calcium levels, and bone acid and alkaline phosphatase activities were compared to those of nonlactating rats fed the same diets. Bone, plasma, and urinary cAMP levels were also studied. Dietary calcium deficiency and/or lactation caused significant loss of bone mass from experimental animals. Urinary cAMP levels reflecting increased parathyroid activity were elevated by the stresses of lactation and calcium deficiency over those of control animals. Plasma and bone levels of cAMP were not different. Bone alkaline and acid phosphatase activities were affected only by the most extreme stress. The results demonstrated that the calcium-deficient lactating rat is an excellent model for bone resorption studies.

Effect of combined administration of furosemide and aspirin on urinary urate excretion in man

Furosemide (20 mg) was administered intravenously to 7 healthy volunteers, before and after 4 days of oral administration of aspirin in uricosuric dosage (1 g daily). Aspirin prevented the decrease in urinary urate excretion induced by furosemide, without interfering with its natriuretic action. This finding is suggested to be the result of the opposite and independent effects of the two drugs on tubular reabsorption of urate.

Lack of effect of fluoride on urinary cAMP excretion in rats

The urinary excretion of cyclic 3'5'-adenosine monophosphate (cAMP) was measured in rats provided a low fluoride diet (less than 0.5 ppm) and drinking water containing either 0 or 25 ppm of fluoride. The pMole cAMP/microgram creatinine ratio decreased with age but was not influenced by fluoride intake.

Renal function and other factors in obstructive jaundice

Renal function and other factors that possibly affect the outcome of operation were measured in 24 patients with obstructive jaundice and in 15 non-jaundiced controls. The preoperative features that were associated with a poor postoperative recovery from obstructive jaundice were a raised serum fibrinogen/fibrin degradation product concentration, infection, hypoalbuminaemia and a low glomerular filtration rate. Preoperative serum fibrinogen/fibrin degradation product concentrations were raised in 4 of the 6 jaundiced patients who died after surgery but in none of the controls, in whom there was no mortality. In the jaundiced patients there was a greater incidence of postoperative renal impairment than in the controls. All patients were given mannitol during operation. Further mannitol was required after surgery in 13 of the 24 jaundiced patients in order to maintain urine flow rate despite adequate intravenous fluids being given. In contrast, only 1 of the 15 control patients required post operative mannitol. It is emphasized that repeated doses of mannitol can lead to a profound natriuresis and adequate intravenous saline should be given.

Butanol extraction of serum and urinary gamma-glutamyltransferase and its application in clinical diagnosis

Gamma-glutamyltransferase (gamma-GT) activity was measured in serum and urine before and after extraction with n-butanol. Residual gamma-GT activity after extraction of normal serum with butanol was more than 75%, whereas for normal urine the figure was less than 68%. The loss of activity from urine was not affected by prior dialysis, and the stabilisation which resulted from adding bovine serum albumin at a concentration of 40 g/l did not approach the residual activity with normal serum. In patients with a variety of renal diseases, residual gamma-GT activity in the urine after butanol extraction was inversely correlated with the creatinine clearance. Butanol extraction was performed on serum samples from 182 patients with a variety of diseases. Eighty-one per cent of patients with elevated gamma-GT activities caused by hepatobiliary disease had an increased loss of activity after butanol extraction. By contrast, only 34% of patients with increases gamma-GT activities in whom there was no clinical or other biochemical evidence of hepatic disease, had increased loss of gamma-GT activity after butanol. The reasons for differences between urinary and serum gamma-GT in response to butanol, and the implications in interpreting serum gamma-GT activities are discussed.

Effects of steady-state plasma vasopressin levels on the distribution of intrarenal blood flow on electrolyte excretion

1. In order to evaluate the effects of arginine vasopressin (AVP) on the distribution of intrarenal blood flow and on electrolyte excretion, steady-state plasma AVP levels (4-8, 19-1, 44-3, and 100-6 micro u./ml.) were produced in anaesthetized dogs, which were hydrated to minimize endogenous anti-diuretic hormone (ADH) release. 2. The urinary excretion of sodium and potassium increased without change in their filtered loads during AVP infusion. 3. Measurement by the 133xenon washout method revealed diphasic blood flow shifts, as a function of the plasma AVP level, between compartment 1 (outer cortex) and compartment 2 (inner cortex and outer medulla) without change in compartment 3 (inner medulla). 4. In a separate study, the radioactive microsphere (15 micronm) method was used with a plasma AVP levels of 19-8 micronu./ml. Blood flow (expressed as % flow/g tissue) decreased in the outer cortex and increased in the inner cortex. 5. Total renal blood flow did not change during infusion of AVP. However, the values measured by 133xenon were lower than those measured by the microsphere method. 6. There was agreement between these two independent methods that blood flow shifted from outer to inner cortex, with no change in total renal flow, at similar plasma AVP levels (19-1 and 19-8 micronu./ml.). The relationship of these intrarenal circulatory changes to the increased electrolyte excretion is discussed.

Filtration of protein in the anti-glomerular basement membrane nephritic rat: a micropuncture study

Production on an anti-glomerular basement membrane (anti-GBM) nephritis in the rat results in a 30-fold increase in glomerular membrane permeability to albumin. The concentration of albumin in glomerular filtrate, estimated from proximal tubular fluid samples, is ten times the normal value. Tubular reabsorption of albumin is not enhanced so that essentially the filtered load is excreted. A nephrotic syndrome develops rapidly. Total kidney glomerular filtration rate (GFR) is reduced to 40% of normal with a proportional reduction in filtration fraction. Glomerulo-tubular balance is maintained since proximal fractional reabsorption remains constant near control levels. Calculated efferent arteriolar plasma colloid osmotic pressure (COP) is about one-third normal. Sodium excretion, sharply curtailed in the first days of anti-GBM nephritis, returns to control values after the fourth postinjection day. Restoration of sodium balance despite reduced filtered load and constant proximal fractional reabsorption must be accomplished by adjustments at a distal site in the nephron.

Renal responses to slight elevations of renal arterial plasma angiotensin II concentration in dogs

1. Angiotensin II was infused into the renal artery of intact kidneys of slightly volume expanded anaesthetized dogs at rates of 125, 250, 500, and 1000 pg/kg body weight per min, resulting in elevations of the calculated renal arterial plasma angiotensin II concentration of 16.9 (s.e.m. =2.1), 35.0 (s.e.m.=4.3), 73.3 (s.e.m.=8.8), and 159.8 (s.e.m.=20.4)pg/ml...

Urinary 17-ketosteroids in diabetic and non-diabetic pregnancies

The excretion of estriol into the maternal urine is an effective means of evaluating the fetus in pregnancies complicated by a number of metabolic disorders, such as chronic hypertension, renal disease, pre-eclampsia, etc. It is generally used in the management of pregnancies complicated by maternal diabetes mellitus even though some question has been raised as to its validity for this disorder. In this study we have evaluated estriol precursors in the form of 17-ketosteroids in the urine of pregnant women with mild diabetes mellitus as well as a non-diabetic control group. Urinary total estrogen excretion was also determined. Diabetics were found to excrete significantly higher amounts of 17-ketosteroids than the non-diabetic group. The possible significance of this finding in relation to the dynamics of estriol production in pregnancy is discussed.

Hyponatremia in sickle cell disease. A renal salt-losing state

Severe hyponatremia has been observed in three children with sickle cell disease, and mild hyponatremia was noted during 36% of random hospitalizations for sickle crisis secondary to vasoocclusion or infection. Serum and urinary electrolytes were therefore studied in such patients. Hyponatremia was found in 52% of patients hospitalized with pain and/or fever, even though they received large amounts of sodium intravenously. Urine sodium losses were high with frequent negative sodium balance and weight loss. When well, these patients did not demonstrate hyponatremia, although urinary salt losses appeared to be just as high, suggesting compensatory salt intake when the children are well. It is essential to monitor electrolytes and urinary losses to manage sickle crisis properly. Six to 11 mEq/kg/day of sodium is suggested as a usual need of these patients during crisis. Sickle cell disease patients have, in addition to the better known defect in concentration of urine, a functional defect in dilution of urine at least during periods of "crisis".

Energy metabolism and hormonal profile in children with edematous protein-calorie malnutrition

Modifications in energy metabolism and endocrine homeostasis (plasma insulin and growth hormone values, glucose and free fatty acid levels, serum thyroxine and TSH, free thyroxine index, and urinary catecholamines) were investigated in eight children with edematous protein-calorie malnutrition. Caloric expenditure was low at admission and correlated linearly with increased caloric intake throughout the study. The hormonal changes at admission were characterized by a negligible insulin response to intravenous arginine or glucose and by markedly elevated growth hormone levels which were neither increased by arginine nor suppressed by intravenous glucose. Serum thyroxine values were low, but free thyroxine index and serum TSH levels were within normal limits. At admission to the study, 24-hour urinary excretion of dopamine and norepinephrine was relatively reduced in relation to the excretion of epinephrine. All these modifications were corrected at time of the recovery study. It is suggested that in edematous protein-calorie malnutrition, insulin acts as the primary regulator of peripheral fuel release and that the high, nonsuppressible growth hormone levels may form part of an important homeostatic mechanism to provide substrates for brain metabolism via lipolysis.

Blood pressure, sodium intake, and sodium related hormones in the Yanomamo Indians, a "no-salt" culture

The Yanomamo Indians are an unacculturated tribe inhabiting the tropical equatorial rain forest of northern Brazil and southern Venezuela who do not use salt in their diet. The group therefore presented an unusual opportunity to study the hormonal regulation of sodium metabolism in a culture with life-long extreme restriction of dietary sodium, with parallel observations on blood pressure. Blood pressures increased from the first to second decade but, in constrast to civilized populations, do not systematically increase during subsequent years of life. In twenty-four hour urine collections on adult male Indians, excretion of sodium averaged only 1 plus or minus 1.5 (SD) mEq. Simultaneous plasma renin activities were elevated and comparable to those of civilized subjects placed for brief periods on 10 mEq sodium diets. Similarly, excretion rates of aldosterone equaled those of acculturated subjects on low sodium diets. The findings suggest that the hormonal adjustments to life-long low sodium intakes are similar to those achieved in acute sodium restriction of civilized man. Parenthetically, these elevated levels of aldosterone and renin were probably the norm for man during much of human evolution and suggest that the values observed in civilized controls are depressed by an excessive salt intake in contemporary diets.

Effect of Hematocrit and Colloid-Induced Changes in Blood Viscosity on Renal Hemodynamics and Renin Release in the Dog

This study compared the effects on the kidney of two major determinants of blood viscosity, the hematocrit and the plasma colloid content. In anesthetized dogs, blood viscosity was raised 30% by increasing hematocrit or infusing isoncotic Dextran 500 while blood volume was kept constant. Neither form of hyperviscosity altered blood pressure, but both forms caused a decrease of about 35% in cardiac output and a comparable rise in total peripheral resistance. Renal blood flow decreased minimally (<10%) in the group of dogs with increased hematocrit but fell more than 30% in the group given Dextran 500. Reciprocal changes occurred in renal vascular resistance. The increase in hematocrit was accompanied by an increase in renin secretion from 146 units/min to 416 units/min ( P <0.001), but Dextran 500 caused a decrease from 167 units/min to 107 units/min ( P <0.025). Sodium and potassium excretion both decreased similarly in the two groups. The data suggest that increased hematocrits are accompanied by renal vasodilatation so that renal vascular resistance rises less than blood viscosity. Dextran hyperviscosity, however, causes no compensatory vasodilatation. This difference in renal vascular response might explain the difference in renin secretion; afferent arteriolar dilatation might stimulate renin release during a rise in hematocrit, and the absence of vasodilatation in colloid hyperviscosity might explain its failure to stimulate renin.