The Influence of Orthophosphate on the Renal Handling of Inorganic Pyrophosphate in Man and Dog

1976 ◽  
Vol 51 (5) ◽  
pp. 435-443 ◽  
Author(s):  
R. G. G. Russell ◽  
Sylvia Bisaz ◽  
H. Fleisch
Keyword(s):  
Urinary Excretion ◽  
Renal Clearance ◽  
Exchange Chromatography ◽  
Urinary Stones ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
Renal Handling ◽  
Inorganic Pyrophosphate ◽  
The Mean ◽  
Hydrolysis Of

1. The urinary excretion of inorganic pyrophosphate (PP1), a known inhibitor of the growth and aggregation of crystals of calcium phosphate and calcium oxalate, increases after ingestion of orthophosphate (P1). This effect may contribute to the apparent ability of oral phosphate to reduce the formation of urinary stones in man. This paper is a study of the mechanism by which P1 increases PP1 excretion, investigated by renal clearance techniques in man and renal arterial infusion in dogs. PP1 in plasma was measured by an isotope-dilution method after ion-exchange chromatography. 2. The mean renal clearance of endogenous PP1 in ten men was 7·9 ± 1·7 (se) ml/min, and the mean ratio of PP1 clearance to creatinine clearance was 008 ±002 (se). The oral ingestion of P1 increased the urinary excretion and renal clearance of PP1 about threefold, without significantly changing its concentration in plasma. 3. In dogs, the infusion of P1 into one renal artery caused a greater increase in urinary PP1 from the infused than from the non-infused kidney, an effect that could be accentuated by simultaneous intravenous infusion of PP1. In dogs, only 1–3% of an injected or infused dose of PP1 appeared intact in the urine, regardless of whether it was infused into the systemic or renal circulation. 4. These results suggest that P1 has a direct effect on the kidney to increase the excretion of PP1. It is possible that P1 either interferes with tubular reabsorption of PP1, perhaps by competing for a common tubular transport mechanism, or that P1 diminishes the intrarenal hydrolysis of PP1.

Thyroxine in unextracted urine

1987 ◽  
Vol 114 (4) ◽  
pp. 503-508 ◽  
Author(s):  
I. Orden ◽  
J. Pie ◽  
M. G. Juste ◽  
J. A. Marsella ◽  
C. Blasco
Keyword(s):  
Urinary Excretion ◽  
Renal Clearance ◽  
Filtration Rate ◽  
Experimental Studies ◽  
Tubular Reabsorption ◽  
Enzyme Hydrolysis ◽  
Renal Handling ◽  
The Mean ◽  
Hypothyroid Patients ◽  
Hyperthyroid Patients

Abstract. The aim of this work was to estimate the daily urinary excretion of free and conjugated thyroxine using a direct radioimmunoassay and enzyme hydrolysis. The renal clearance of free T4 was also determined. The mean urinary values of free and total T4 (mean ± 1 sd) in 112 euthyroid controls were 1353 ± 496 and 1855 ± 651 pmol/24 h, respectively. Urinary excretion of free hormone in 13 hyperthyroid patients was 5552 ± 4320 pmol/24 h and total T4 was 8122 ± 7219 pmol/24 h. Urinary free T4 excretion was 223 ± 223 pmol/24 h in hypothyroid patients and total T4 was 542 ± 490 pmol/24 h. These results indicate that daily urinary T4 excretion is a good indicator of thyroid function. The mean renal clearance of free T4 was 52 ± 19 ml/min (mean ± 1 sd) in euthyroid patients, 53.7 ± 12.3 ml/min in hyperthyroid patients, and 67.6 ± 13.1 ml/min in hypothyroid patients. We estimated the endogenous creatinine renal clearance as a control of the renal filtration rate. The data suggest that there is T4 filtration of unbound T4 and partial tubular reabsorption. Further experimental studies will be necessary to clarify the renal handling of thyroxine as well as the fate of reabsorbed T4.

ON THE VALUE OF SOME PARAMETERS OF ADRENOCORTICAL GLUCOCORTICOID FUNCTION

1963 ◽  
Vol 44 (4) ◽  
pp. 499-504 ◽  
Author(s):  
M. Van Der Straeten ◽  
A. Vermeulen ◽  
N. Orie ◽  
P. Regniers
Keyword(s):  
Urinary Excretion ◽  
Adrenal Cortex ◽  
Isotope Dilution ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
Steroid Excretion ◽  
Colorimetric Methods

ABSTRACT The authors studied the correlation between cortisol production, as measured by an isotope dilution method, and the urinary excretion of total and free Porter-Silber chromogens, as well as of 17-ketogenic steroids. Although a significant correlation exists between total Porter-Silber chromogens, 17-ketogenic steroid excretion and cortisol production, discrepancies are occasionally observed. Hence, different colorimetric methods should be used to assess the glucocorticoid activity of the adrenal cortex.

Serial Studies of the Renal Clearance of Urate and Inulin during Pregnancy and after the Puerperium in Normal Women

1974 ◽  
Vol 47 (6) ◽  
pp. 559-565 ◽  
Author(s):  
P. F. Semple ◽  
W. Carswell ◽  
J. A. Boyle
Keyword(s):  
Urinary Excretion ◽  
Renal Clearance ◽  
Post Partum ◽  
Late Pregnancy ◽  
Serum Urate ◽  
Control Value ◽  
The Mean ◽  
Normal Women ◽  
In Pregnancy ◽  
Made In

1. A serial study of renal clearance of urate and inulin was made in thirteen normal women in early, mid and late pregnancy and 6–15 weeks after delivery. 2. The mean serum urate concentration was low in early and mid pregnancy but rose in late pregnancy towards the control value. 3. Clearances of urate and inulin were consistently elevated throughout pregnancy to about 150% of the post-partum values. The ratio of clearance of urate to clearance of inulin was the same in pregnancy as it was after the puerperium. 4. The urinary excretion of urate was increased only in late pregnancy.

scholarly journals Analysis of Concentration and 13C Enrichment of d-Galactose in Human Plasma

2000 ◽  
Vol 46 (5) ◽  
pp. 612-619 ◽  
Author(s):  
Peter Schadewaldt ◽  
Hans-Werner Hammen ◽  
Kamalanathan Loganathan ◽  
Annette Bodner-Leidecker ◽  
Udo Wendel
Keyword(s):  
Stable Isotope ◽  
Human Plasma ◽  
Internal Standard ◽  
Exchange Chromatography ◽  
Isotope Dilution Method ◽  
Spectrometric Analysis ◽  
Dilution Method ◽  
Diabetic Patients ◽  
High Concentration ◽  
Limit Of Quantification

Abstract Background: A stable-isotope dilution method for the sensitive determination of d-galactose in human plasma was established. Methods: d-[13C]Galactose was added to plasma, and the concentration was measured after d-glucose was removed from the plasma by treatment with d-glucose oxidase and the sample was purified by ion-exchange chromatography. For gas chromatographic–mass spectrometric analysis, aldononitrile pentaacetate derivatives were prepared. Monitoring of the [MH-60]+ ion intensities at m/z 328, 329, and 334 in the positive chemical ionization mode allowed the assessment of 1-12C-, 1-13C-, and U-13C6-labeled d-galactose, respectively. The d-galactose concentration was quantified on the basis of the 13C-labeled internal standard. Results: The method was linear (range examined, 0.1–5 μmol/L) and of good repeatability in the low and high concentration ranges (within- and between-run CVs <15%). The limit of quantification for plasma d-galactose was <0.02 μmol/L. Measurements in plasma of postabsorptive subjects yielded d-galactose concentrations (mean ± SD) of 0.12 ± 0.03 (n = 16), 0.11 ± 0.04 (n = 15), 1.44 ± 0.54 (n = 10), and 0.17 ± 0.07 (n = 5) μmol/L in healthy adults, diabetic patients, patients with classical galactosemia, and obligate heterozygous parents thereof, respectively. These data were considerably lower (3- to 18-fold) than the values of a conventional enzymatic assay. The procedure was also applied successfully in a stable-isotope turnover study to evaluate endogenous d-galactose formation. Conclusions: The present findings establish that detection of d-galactose from endogenous sources is feasible in human plasma and show that erroneously high results may be obtained by enzymatic methods.

Oligopeptides: mechanism of renal clearance depends on molecular structure

1992 ◽  
Vol 263 (1) ◽  
pp. F109-F115 ◽  
Author(s):  
H. Minami ◽  
H. Daniel ◽  
E. L. Morse ◽  
S. A. Adibi
Keyword(s):  
Molecular Structure ◽  
Urinary Excretion ◽  
Renal Clearance ◽  
Brush Border ◽  
Hydrolytic Activity ◽  
Renal Tubular Cells ◽  
Relative Contribution ◽  
Perfusion Studies ◽  
Renal Tubular ◽  
Hydrolysis Of

We have investigated the relative contribution of hydrolysis, intact transport and urinary excretion to the renal clearance of Gly-Sar, Gly-Sar-Sar, and Gly-Gly-Sar in fed and starved rats. The results obtained from isolated kidney perfusion studies are summarized as follows: 1) clearance was fastest for Gly-Gly-Sar and slowest for Gly-Sar-Sar, 2) urinary excretion of Gly-Sar-Sar exceeded that of Gly-Gly-Sar or Gly-Sar, 3) there was accumulation of products of hydrolysis of Gly-Gly-Sar in the perfusate but not of Gly-Sar or Gly-Sar-Sar, 4) isolated brush-border and basolateral membranes of renal tubular cells lacked hydrolytic activity against Gly-Sar and Gly-Sar-Sar but possessed hydrolytic activity against Gly-Gly-Sar, 5) an excess amount of Gly-Sar-Sar reduced the rate of clearance of Gly-Gly-Sar by approximately 40% and significantly increased urinary excretion of this peptide, 6) the nonfiltering kidney cleared Gly-Gly-Sar at a rate which was 50% of that of the filtering kidney but did not clear Gly-Sar, and 7) starvation for 96 h was without a significant effect on the renal clearance of either Gly-Sar or Gly-Sar-Sar but significantly reduced the renal clearance of Gly-Gly-Sar and the brush-border membrane hydrolase activity against this peptide. We conclude that the molecular structure determines the affinity of oligopeptides for the membrane transport and hydrolytic systems, which, in turn, determines their efficiency for clearance by the kidney.

Rapid fluorometry of estrogens in nonpregnancy urine, with use of chloroform extraction and purification by anion-exchange chromatography.

1979 ◽  
Vol 25 (2) ◽  
pp. 230-234 ◽  
Author(s):  
C Goutte-Coussieu ◽  
G Habrioux ◽  
D Eichenberger ◽  
M F Jayle
Keyword(s):  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Gas Chromatography Mass Spectrometry ◽  
Automatic Extraction ◽  
Normal Limits ◽  
Extraction And Purification ◽  
The Mean ◽  
Working Day ◽  
Method Of Extraction ◽  
Hydrolysis Of

Abstract We describe a new method of extraction and purification of estrogens in low concentration in urine, involving a rapid enzymic hydrolysis of a 10-mL sample, automatic extraction (in a tube) with CHCl3/ethyl acetate, purification by chromatography on a disposable "mini-column" of AG 1-X2, and fluorometry by continuous flow according to Itrich's procedure [Acta Endocrinol. (Copenhagen) 35, 34 (1960)]. Conditions of hydrolysis, extraction, and purification were studied. Within-day precision (CV) was 7.5%, the mean between-day precision 8.5%. The sensitivity was 6 microgram of total estrogens per liter of urine. The specificity was assessed particularly by comparison with the results obtained by Schöller et al. [Acta Endocrinol. (Copenhagen) 57, suppl. 107 (1966)] and by gas-chromatography-mass-spectrometry. The normal limits as calculated by this technique were identical to values reported by others. The technique is rapid; results are obtained in 3 h. It is quite suitable for routine determinations: 100 assays can be done by a team of three technicians in one working day.

Sheep lactate entry-rate measurements: error due to sampling jugular blood.

1977 ◽  
Vol 233 (3) ◽  
pp. E138
Author(s):  
P E Reilly ◽  
L G Chandrasena
Keyword(s):  
Venous Blood ◽  
Lactate Concentration ◽  
Specific Radioactivity ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
Entry Rate ◽  
Blood Samples ◽  
The Mean ◽  
Carotid Arterial ◽  
Arteriovenous Difference

Carotid arterial and jugular venous blood samples were taken simultaneously during primed continuous infusions of L-[U-14C]lactate in four sheep. The mean rate (n = 4) of total net formation of lactate (0.394 +/- 0.047 mg C/min per kg) calculated from the results obtained by analyzing the jugular blood samples for lactate concentration and specific radioactivity was significantly higher (0.01 greater than P greater than 0.005) than the mean rate (n = 4) calculated from the results of analysis of the arterial samples (0.302 +/- 0.036 mg C/min per kg). The error in the estimation of the rate of total net formation of lactate due to jugular sampling resulted from the negative arteriovenous difference found for lactate across the tissues of the head. These results illustrate the general need for examination of the suitability of venous sampling in experiments that make use of the continuous infusion isotope-dilution method.

THE DETERMINATION OF CORTISOL AND CORTICOSTERONE PRODUCTION RATES BY AN ISOTOPE DILUTION METHOD

1963 ◽  
Vol 43 (3) ◽  
pp. 430-438 ◽  
Author(s):  
M. Van Der Straeten ◽  
A. Vermeulen ◽  
N. Orie
Keyword(s):  
Isotope Dilution ◽  
Hormone Secretion ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
Production Rates ◽  
Production Ratio ◽  
The Mean ◽  
Normal Men ◽  
Secretion Rates

ABSTRACT Cortisol and corticosterone productions were measured by an isotope dilution technique described by Cope & Black in 1958. Provided that some minor modifications are introduced which increase the specificity, this method is very valuable for measuring corticoid hormone secretion rates. Cortisol production in normal men varied between 15.9 mg and 30.9 mg per 24 h with a mean of 21.4 mg; corticosterone production varied between 1.6 mg and 5.5 mg with a mean of 3.4 mg. The mean F/B production ratio was 6.7. In a few patients with adrenal hypo- and hyperfunction, production rates were determined by the same technique.

Quantification of small-scale heterogeneity in aquatic aminopeptidase activity

2020 ◽  
Vol 84 ◽  
pp. 127-140
Author(s):  
BM Gaas ◽  
JW Ammerman
Keyword(s):  
Chlorophyll Fluorescence ◽  
Leucine Aminopeptidase ◽  
Hudson River ◽  
Aminopeptidase Activity ◽  
Small Scale ◽  
Analysis Instrument ◽  
Sequential Samples ◽  
Degree Of Confidence ◽  
The Mean ◽  
Hydrolysis Of

Leucine aminopeptidase (LAP) is one of the enzymes involved in the hydrolysis of peptides, and is sometimes used to indicate potential nitrogen limitation in microbes. Small-scale variability has the potential to confound interpretation of underlying patterns in LAP activity in time or space. An automated flow-injection analysis instrument was used to address the small-scale variability of LAP activity within contiguous regions of the Hudson River plume (New Jersey, USA). LAP activity had a coefficient of variation (CV) of ca. 0.5 with occasional values above 1.0. The mean CVs for other biological parameters—chlorophyll fluorescence and nitrate concentration—were similar, and were much lower for salinity. LAP activity changed by an average of 35 nmol l-1 h-1 at different salinities, and variations in LAP activity were higher crossing region boundaries than within a region. Differences in LAP activity were ±100 nmol l-1 h-1 between sequential samples spaced <10 m apart. Variogram analysis indicated an inherent spatial variability of 52 nmol l-1 h-1 throughout the study area. Large changes in LAP activity were often associated with small changes in salinity and chlorophyll fluorescence, and were sensitive to the sampling frequency. This study concludes that LAP measurements in a sample could realistically be expected to range from zero to twice the average, and changes between areas or times should be at least 2-fold to have some degree of confidence that apparent patterns (or lack thereof) in activity are real.

A COMPARISON OF TWO METHODS FOR MEASUREMENT OF ALDOSTERONE SECRETION RATE IN MAN

1966 ◽  
Vol 53 (2) ◽  
pp. 177-188 ◽  
Author(s):  
P. Lund-Johansen ◽  
T. Thorsen ◽  
K. F. Støa
Keyword(s):  
Urinary Excretion ◽  
Normal Subjects ◽  
Secretion Rate ◽  
Aldosterone Secretion ◽  
Simple Method ◽  
Mean Values ◽  
Pathological Conditions ◽  
Significant Difference ◽  
Derivative Method ◽  
The Mean

ABSTRACT A comparison has been made between (A), a relatively simple method for the measurement of aldosterone secretion rate, based on paper chromatography and direct densitometry of the aldosterone spot and (B) a more elaborate isotope derivative method. The mean secretion rate in 9 normal subjects was 112 ± 26 μg per 24 hours (method A) and 135 ± 35 μg per 24 hours (method B). The »secretion rate« in one adrenalectomized subject after the intravenous injection of 250 μg of aldosterone was 230 μg per 24 hours (method A) and 294 μg per 24 hours (method B). There was no significant difference in the mean values, and correlation between the two methods was good (r = 0.80). It is concluded that the densitometric method is suitable for clinical purposes as well as research, being more rapid and less expensive than the isotope derivative method. Method A also measures the urinary excretion of the aldosterone 3-oxo-conjugate, which is of interest in many pathological conditions. The densitometric method is obviously the less sensitive and a prerequisite for its use is an aldosterone secretion of 20—30 μg per 24 hours. Lower values are, however, rare in adults.

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