Renal excretion of urobilinogen in the dog. (9/15)

The renal excretion of urobilinogen was studied in dogs by standard clearance techniques. The use of radiochemically pure tritiated mesobilirubinogen as a representative urobilinogen afforded much greater analytical precision than can be obtained with the usual colorimetric and fluorimetric techniques which are only semiquantitative. With constant plasma levels of urobilinogen, raising urinary pH from 5 to 8 increased urobilinogen excretion from about 30% to up to 200% of the filtered load. When urinary pH was kept constant, changes in blood pH had no effect on urobilinogen excretion. Increases in urinary flow had no effect on urobilinogen excretion when the urine was alkaline but increased excretion markedly during aciduria. Probenecid did not influence urobilinogen excretion by the kidney. It is concluded that urobilinogen is excreted by a three-component system of glomerular filtration, active secretion, and pH-dependent nonionic diffusion in the distal nephron. Urobilinogen is a weak acid, and this mode of excretion is similar to that of other weak, organic acids, such as salicylates. These results indicate that urinary pH and flow must be considered in the clinical interpretation of measurements of urinary urobilinogen.  (+info)

Absorption of bile pigments by the gall bladder. (10/15)

A technique is described for preparation in the guinea pig of an in situ, isolated, vascularized gall bladder that exhibits normal absorptive functions. Absorption of labeled bile pigments from the gall bladder was determined by the subsequent excretion of radioactivity in hepatic bile. Over a wide range of concentrations, unconjugated bilirubin-(14)C was well absorbed, whereas transfer of conjugated bilirubin proceeded slowly. Mesobilirubinogen-(3)H was absorbed poorly from whole bile, but was absorbed as rapidly as unconjugated bilirubin from a solution of pure conjugated bile salt. Bilirubin absorption was not impaired by iodoacetamide, 1.5 mM, or dinitrophenol, 1.0 mM, even though water transport was affected. This indicated that absorption of bilirubin was not dependent upon water transport, nor upon energy-dependent processes. The linear relationship between absorption and concentration of pigment at low concentrations in bile salt solutions suggested that pigment was transferred by passive diffusion. At higher pigment concentrations or in whole bile, this simple relationship was modified by interactions of pigment with bile salts and other constituents of bile. These interactions did not necessarily involve binding of bilirubin in micelles. The slow absorption of the more polar conjugates and photo-oxidative derivatives of bilirubin suggested that bilirubin was absorbed principally by nonionic, and partially, by ionic diffusion. Concentrations of pure conjugated bile salts above 3.5 mM were found to be injurious to the gall bladder mucosa. This mucosal injury did not affect the kinetics of bilirubin absorption. During in vitro incubation of bile at 37 degrees C, decay of bilirubin and hydrolysis of the conjugate proceeded as first-order reactions. The effects of these processes on the kinetics of bilirubin absorption, and their possible role in the formation of "white bile" and in the demonstrated appearance of unconjugated bilirubin in hepatic bile, are discussed.  (+info)

Urinary urobilinogen determined by a mercuric chloride procedure. (11/15)

In this quantitative assay, urinary urobilinogen is oxidized to urobilin with iodate in an acid medium, the pH is adjusted to 6 with sodium acetate, and the mixture is reacted with alcoholic HgCl2 solution, extracted with CHCl3, the measured spectrophotometrically at 513 nm. The artificial standards of previous methods have been replaced with crystalline stercobilin IX (commercially available), a urobilin closely related to the urinary urobilins. The reproducibility of the method, as assessed from 10 replicates of a single urine specimen to which urobilinogen was added, gave a coefficient of variation of 3.9%. Analytical recovery of urobilinogen added to urines was 90.4% (SD 14.5%). Bilirubin, biliverdin, mesobilirubin, coproporphyrin I, uroporphyrin I, and porphobilinogen do not interfere.  (+info)

Faecal urobilinogen levels and pH of stools in population groups with different incidence of cancer of the colon, and their possible role in its aetiology. (12/15)

Mean faecal urobilinogen levels and the pH of stools were both found to be higher in subjects from a population group at high risk of developing cancer of the colon than in subjects matched for age, sex and socioeconomic status from a low-risk population group. An alkaline reaction of the colon contents seems to have a tumorigenic effect by a direct action on the mucus of the mucous cells. An acidic reaction, on the other hand, appears to be protective. These differences are dependent on the patterns of diet and manner of eating. Proper mastication of food, roughage, cellulose and vegetable fibre, and short-chain fatty acids of milk and fermented milk products in the diet appear to be protective.  (+info)

A 4-week subcutaneous toxicity study of recombinant human interferon alpha A (LBD-007) in Sprague-Dawley rats. (13/15)

Recombinant human interferon alpha A (code name: LBD-007) was subcutaneously administered to both sexes of Sprague-Dawley rats at the doses of 0, 6, 12 and 24 x 10(6) IU/kg of body weight five days per week for 4 weeks to evaluate the subchronic toxicity. 20 to 50% of rats except the male control group showed minimal to mild, focal to multifocal renal mineralization. Whether renal mineralization is related to the test substance is not elucidated. Male rats dosed at 24 x 10(6) IU/kg showed the decrease of the absolute kidney weights and the increase of the brain relative weights. Female rats dosed at 24 x 10(6) IU/kg showed the increase of the absolute and relative ovary weights, and the decreases of specific gravity, bilirubin and urobilinogen in urine. However, no drug-related changes were noted in clinical findings, body weights, food consumption, water consumption, hematology, blood clinical chemistry and necropsy findings. Based on the results it is concluded that the estimated subcutaneous non-toxic dose of the recombinant human interferon alpha A (LBD-007) in rats is (6 approximately 12) x 10(6) IU/kg.  (+info)

Evaluation of Ames' "Clini-Tek". (14/15)

Reproducibility of reading "N-Multistix" dipsticks by a semi-automated urinalysis instrument (Ames' "Clini-Tek") has been described for artifically prepared samples. Glucose, ketone, urobilinogen, and nitrite showed high reproducibility (greater than 90%) for reading multiple samples at predetermined analyte concentrations. Determination of proteinuria showed the lowest proportion of false positives (2-3%) and false negatives (0%). Determination of hemoglobinuria and bilirubinuria by dipsticks were the least reproducible. Urobilinogen showed no interference from bilirubin in concentrations up to 32 mg/liter. Precision was high for results for quality-control capsules provided by the manufacturer.  (+info)

Urinalysis by use of multi-test reagent strips: two dipsticks compared. (15/15)

We compared Ames' "N-Multistix" with Boehringer's "Combur-8" ("Chemstrip-8") multi-test urine reagent strips by analysis of contrived urine specimens, testing accuracy, precision, specificity, and limits of detection of both products. Relative cost and ease of use were also examined. Each brand of urinary dipstick had specific advantages but it is unlikely that patient care would be adversely affected by preferential use of either product.  (+info)