bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ammoniagenesis by the Isolated Perfused Rat Kidney: The Critical Role of Urinary Acidification
Authors: Tannen R. L. , Ross B. D. 
Published: August 2015

1. The effect of metabolic acidosis simulated in vitro on ammoniagenesis was investigated by using the isolated kidney of the rat perfused with an albumin Krebs—Henseleit medium containing glutamine and glucose.
2. Addition of HCl to a perfusate of normal bicarbonate concentration resulted in a prompt increase in urine flow rate, decrease in fractional sodium reabsorption and decrease in urine pH.
3. A minimum urine pH as low as 5·15 was achieved, with an average value of 5·92, indicating that this preparation has the capacity to acidify normally.
4. In contrast with studies in vitro with other preparations, with the functional perfused kidney a diminution in perfusate bicarbonate concentration resulted in a prompt increase in ammonia production, which was strikingly correlated with the decrease in urine pH.
5. The increase in ammonia production was diminished in studies carried out with a non-urinating kidney, in comparison with those that exhibited significant urine acidification.
6. These data suggest that a decrease in urine pH with trapping of ammonia in the urine may be a critical stimulus for increased ammonia production in acute metabolic acidosis.
Carbohydrate Moieties of Glycoproteins in Human Hepatic and Gall-Bladder Bile, Gall-Bladder Mucosa and Gall Stones
Authors: Lee S. P. , Lim T. H. , Scott A. J. 
Published: August 2015

1. The soluble glycoproteins of human bile, gall-bladder mucosa and gall stones have been extracted and hydrolysed, and the monosaccharides analysed by gas-liquid chromatography.
2. Human biliary glycoproteins contained 55–75% of carbohydrate, the major monosaccharide components being galactose, fucose and N-acetylglucosamine, accounting for 70–85% of all the monosaccharides. Mannose, glucose, N-acetylgalactosamine and N-acetylneuraminic acid (sialic acid) were also present. N-Acetylneuraminic acid was present in large amounts in the gall-bladder mucosa and bile of one ulcerated and markedly inflamed gall bladder.
3. The proportion of monosaccharides in soluble glycoproteins of mucosa and bile were not different in samples from subjects with or without gall stones.
4. Gall stones were analysed for cholesterol, calcium and bilirubin and classified as ‘cholesterol stones’ (7/10) and ‘pigment stones’ (3/10). Both cholesterol and pigment stones contain a variable amount of glycoprotein. The pattern of carbohydrate constituents was similar to that present in the gall-bladder mucosa and bile in the same subject. There was also no major difference between the pattern found in ‘cholesterol’ and ‘pigment’ stones.
5. Evidence and argument are presented suggesting that some glycoprotein is secreted by the gall bladder and incorporated into gall stones. This calls for further work upon the influence of these carbohydrate-rich macromolecules on cholesterol solubilization in mixed micelles.
The Mechanism of Amphotericin-Induced Distal Acidification Defect in Rats
Authors: Julka Naresh K. , Arruda Jose A. L. , Kurtzman N. A. 
Published: August 2015

1. The effect of chronic and acute administration of amphotericin B on renal function, especially urinary acidification, was studied in rats. Chronic intraperitoneal administration of amphotericin B resulted in blood concentrations similar to or higher than those seen in patients treated with the antibiotic, but failed to produce hyperchloraemic acidosis. The minimum urine pH achieved during NH4Cl-induced acidosis was significantly higher in amphotericin-treated rats than in controls; net acid excretion, however, was not significantly different from that of controls. These data were interpreted as indicating the presence of an incomplete distal acidification defect.
2. The ability to raise urine-blood (U-B)Pco2 during alkalinization of the urine was examined in another group of amphotericin-treated rats. The data on amphotericin-treated rats could be artificially divided into two groups. One group had a normal glomerular filtration rate (GFR) and was able to raise the (U-B)Pco2 gradient during administration of the HCO−3 to the same as that seen in control rats infused with the vehicle for amphotericin, sodium deoxycholate. The second group, which comprised only 15% of the total, had a decreased glomerular filtration rate and an abnormally low (U-B)Pco2. The normal (U-B)Pco2 was interpreted as the result of normal H+ secretion during alkalinization of the urine. The low (U-B)Pco2 in the second group was attributed to the low urinary HCO−3 concentration.
3. In order to investigate the effect of large concentrations of amphotericin on distal H+ secretion, amphotericin was administered acutely to HCO−3-loaded rats. Acute intravenous administration of amphotericin resulted in a significant decrease in (U-B)Pco2 and urine HCO−3 concentration; the decrease in urinary Pco2 was of greater magnitude than the decrease in urine HCO−3 concentration, leading to a rise in urine pH. The maximum urine pH achieved during HCO−3 loading (maximal urine HCO−3 was the same in both groups) was significantly higher in the animals infused acutely with amphotericin than in controls, thus indicating that amphotericin-treated animals have a distal acidification defect. These data are compatible with the hypothesis that amphotericin induces an acidification defect by increasing H+ back-diffusion in the form of carbonic acid or dissolved CO2 when the urine is highly alkaline and in the form of weak acid or proton when the urine is acid.
Post- and Pre-Natal Assessment of α-l-Iduronidase Deficiency with a Radiolabelled Natural Substrate
Authors: Hopwood J. J. , Muller Vivienne , Pollard A. C. 
Published: August 2015

1. α-l-Iduronidase activity was assayed by incubation of iduronosyl anhydro[1-3H]mannitol 6-sulphate with homogenates of cultured skin fibroblasts, amniotic cells and leucocytes derived from normal individuals, patients affected with α-l-iduronidase deficiency disorder (mucopolysaccharidosis type I: Hurler, Scheie and Hurler-Scheie compound) and parents of such patients.
2. The assay for α-l-iduronidase, described for use with these cell types, clearly distinguished affected homozygotes from heterozygotes and normal controls.
3. The mean specific activity of α-l-iduronidase in homogenates prepared from cultured skin fibroblasts and leucocytes from more than seven obligate heterozygotes for mucopolysaccharidosis type I was found to be about one-half of the mean of more than 40 normal controls. A number of heterozygotes had α-l-iduronidase activity that identified them as carriers; others had values clearly within the normal range. Thus heterozygote detection of mucopolysaccharidosis type I is not certain.
4. With iduronosyl anhydro[1-3H]mannitol 6-sulphate used as substrate, cell types from five pregnancies at risk for α-l-iduronidase deficiency were examined; each foetus was predicted to be unaffected. For one foetus it was not possible from measurements of total enzyme activity alone to distinguish between the heterozygous carrier state and affected homozygote. The difficulty was resolved by comparing Michaelis-Menten kinetics of this enzyme in fibroblasts derived from the propositus, mother and normal controls with the kinetics of the enzyme in amniotic cells isolated from the foetus at risk and from normal controls.
Plasma Renin Activity and Sodium, Potassium and Water Excretion during Reversal of Hypertension in the One-Clip, Two-Kidney Hypertensive Rat
Authors: Ten Berg R. G. M. , Leenen F. H. H. , De Jong W. 
Published: August 2015

1. The effect of removal of the clip on blood pressure, plasma renin activity and the excretion of water, sodium and potassium was studied in renal hypertensive rats. Hypertension was induced by application of a clip with an internal diameter of 0·20 mm, which was removed after 1, 2 or 3 weeks, and by using a clip with an internal diameter of 0·25 mm, which was removed after 2 weeks. The contralateral kidney remained undisturbed.
2. Blood pressure was almost normal 24 h after the removal of the clip; 70–90% of the total decrease in blood pressure occurred within 2–5 h.
3. The increased plasma renin activity, which was observed 2 and 3 weeks after application of a 0·20 mm clip, had returned to control values 24 h after removal of the clip. One week after application of a 0·20 mm clip, and 2 weeks after a 0·25 mm clip, plasma renin activity did not differ significantly from control values, before as well as after unclipping.
4. No significant differences were found between unclipped and sham-operated renal hypertensive rats, nor between the latter and the sham-operated normotensive control rats for water, sodium and potassium excretion, and for change in body weight, during the 24 h after the removal of the clip.
5. It is concluded that urinary loss of water and/or sodium does not play an important role in the acute decrease of blood pressure which occurs after the removal of a renal artery clip in one-clip, two-kidney hypertensive rats. A decrease in peripheral plasma renin activity can only partly explain the reversal of the hypertension.
Vitamin D and Magnesium Absorption in Man
Authors: Hodgkinson A. , Marshall D. H. , Nordin B. E. C. 
Published: August 2015

1. The effects of vitamin D and its hydroxylated derivatives on calcium and magnesium absorption have been examined in 47 balance studies on patients with various disorders of calcium or bone metabolism.
2. Vitamin D significantly increased the mean net absorption of calcium and also the calcium balance. The mean net absorption of magnesium was also significantly increased although the rise was much less than that of calcium and the mean magnesium balance was unaffected.
3. It is suggested that the slight effect of vitamin D on magnesium absorption may be incidental to its stimulation of active calcium transport, since the latter system has weak affinities for other alkaline earth ions including strontium, barium and magnesium.
Heparin-Released Plasma Lipases in Chronic Renal Failure and after Renal Transplantation
Authors: Crawford G. A. , Savdie E. , Stewart J. H. 
Published: August 2015

1. Post-heparin plasma from normal subjects, patients with chronic renal failure and recipients of renal allografts were subjected to affinity chromatography on heparin—agarose (Sepharose 4B) columns to separate two fractions representing hepatic lipase and lipoprotein lipase respectively.
2. The optimum conditions for assay of each fraction were determined for both normal and uraemic plasma.
3. Normal males had activities of hepatic lipase which were higher, and activities of lipoprotein lipase which were lower, than normal females. There was no consistent relationship to age for either enzyme.
4. Thirty patients with chronic renal failure untreated by dialysis had significantly elevated serum triacylglycerol concentrations, and significantly lowered lipoprotein lipase activities when compared with control groups with similar ages for each sex. However, only in uraemic males was hepatic lipase activity significantly reduced.
5. In a study of female patients with chronic renal failure, there were no significant differences in activities of hepatic lipase or lipoprotein lipase or concentrations of serum triacylglycerols between eight patients receiving dialysis treatment and eight untreated by dialysis.
6. Although serum triacylglycerol concentrations were raised in the group of 15 renal transplant recipients, lipase activities were not diminished. The only significant change was elevation of hepatic lipase activity in female graft recipients.
7. No relationship was found between the enzyme activities and fasting serum triacylglycerol concentrations in any group. However, there was a weak inverse correlation between serum creatinine and hepatic lipase in female patients from both renal failure and transplant groups.
8. Similar results were obtained when the enzymes were assayed with, as substrate, a laboratory-prepared emulsion of 14C-labelled triolein in water with soya-bean lecithin as emulsifier, or commercially prepared soya-bean oil in water, emulsified with egg-yolk lecithin and containing glycerol (Intralipid).
Parathyroid Function in Primary Osteoporosis
Authors: Bouillon R. , Geusens P. , Dequeker J. , De Moor P. 
Published: August 2015

1. Parathyroid hormone and 25-hydroxy-vitamin D concentrations were measured in patients with severe primary osteoporosis and the results were compared with those found in normal subjects and in patients with primary hyperparathyroidism of vitamin D deficiency.
2. The parathyroid hormone concentrations in 19 patients with primary osteoporosis were within the normal range, both in the basal state (215 ± 85 ng/l, mean ± sd) and during a maximal stimulation (460 ±154 ng/l) induced by the infusion of disodium EDTA (70 mg/kg body weight). Increased serum concentrations of parathyroid hormone were found in patients with primary hyperparathyroidism (821 ± 323 ng/l, n = 33) and nutritional vitamin D deficiency (565 ± 144 ng/l, n = 11).
3. Serum 25-hydroxy-vitamin D concentrations (16·8 ± 7·7 μg/l) were found to be normal in patients with primary osteoporosis. Slightly (9·1 ± 2·1 μg/l) or markedly lower (2·2 ± 1·1 μg/l) 25-hydroxy-vitamin D concentrations were found respectively in patients with primary hyperparathyroidism and secondary hyperparathyroidism due to vitamin D deficiency. The serum concentration of the vitamin D-binding protein was normal in all groups.
4. A clearcut separation was therefore obtained between osteoporotic subjects (normal parathyroid hormone and normal 25-hydroxy-vitamin D concentrations) and patients with either primary hyperparathyroidism (increased parathyroid hormone and normal 25-hydroxy-vitamin D) or vitamin D deficiency (high parathyroid hormone and very low 25-hydroxy-vitamin D).
Urine Reinfusion Diuresis and Natriuresis in Rats: Role of Water, Electrolytes and Urea
Authors: Norman R. A. , Coleman T. G. , Kastner P. R. 
Published: August 2015

1. The purpose of this study was to determine the role of reinfused water, electrolytes and urea in the diuresis and natriuresis of urine reinfusion.
2. Three groups of rats underwent 5 h of urine reinfusion. The first group served as a control, and during urine reinfusion the urinary volume and sodium excretion increased to 10 or 12 times control values.
3. In a second group, urine reinfusion was followed by 2 h of infusion of Ringer solution at a rate equal to the urine flow rate; 71% of the diuresis and 75% of the natriuresis resulting from urine reinfusion were maintained.
4. In a third group, urine reinfusion was followed by infusion of Ringer solution with urea added. The infusion rate was equal to urine flow rate and the concentration of urea was equal to that in the urine; 98% of the diuresis and 102% of the natriuresis were maintained.
5. These results indicate that the majority of urine-reinfusion diuresis and natriuresis is due to reinfused volume and electrolytes, and the remainder, in these experiments at least, could be explained by the reinfused urea. Therefore there was no need to postulate additional urinary natriuretic factors to explain the results of urine reinfusion.
Mucosal Enzymes in Human Inflammatory Bowel Disease with Reference to Neutrophil Granulocytes as Mediators of Tissue Injury
Authors: Kane S. P. , Vincenti A. C. 
Published: August 2015

1. Biopsies of rectal mucosa were obtained for histology and enzyme analysis from 32 patients with inflammatory and functional bowel disorders, and the biopsies were classified morphologically as active colitis, quiescent colitis or normal.
2. Supernatant fractions of biopsy homogenates were assayed for their content of the proteolytic enzymes α-chymotrypsin, elastase and cathepsin D, and of protein, unsaturated vitamin B12-binding capacity, lysozyme, myeloperoxidase and N-acetyl-β-glucosaminidase.
3. Mean unsaturated vitamin B12-binding capacity was significantly raised above normal in the active colitic mucosa, and mean lysozyme activity was raised above normal in both active and quiescent mucosae.
4. In active colitic mucosa there was no rise above normal in mean activities of any of the proteolytic enzymes, though a significant fall below normal occurred in mean N-acetyl-β-glucosaminidase activity in the active colitic group.
Characteristics of a Renin-Binding Substance for the Conversion of Renin into a Higher-Molecular-Weight Form in the Dog
Authors: Kawamura Minoru , Ikemoto Fumihiko , Funakawa Susumu , Yamamoto Kenjiro 
Published: August 2015

1. Renal cortical homogenates of the dog were subjected to sieve separation, a Nucleopore Filter being used to separate the renin granules.
2. The molecular weight of renin in the granules was estimated to be about 40 000 by gel filtration. Renin was converted into a higher-molecular-weight form (60 000) by mixing with cytosol in the presence of sodium tetrathionate, a thiol inhibitor.
3. When cytosol was pretreated with acid (pH 30) or heating (100°C), the molecular-weight conversion did not occur.
4. Cytosol was separated into three parts by gel filtration. Fraction A included substances with a molecular weight of over 47 000, fraction B from 47 000 to 32 000, and fraction C from 32 000 to 15 000. The mixture of renin in the granules with fraction A and sodium tetrathionate resulted in the formation of a higher-molecular-weight form of the enzyme, but no change in molecular weight was detected when renin was mixed with fractions B or C and sodium tetrathionate.
Effect of Phlorhizin on Renal Glucose and Phosphate Transport in the Dog
Authors: Wen Sung-Feng 
Published: August 2015

1. Clearance and micropuncture studies were performed in 19 thyroparathyroidectomized dogs to examine the inter-relationship between the renal transport of sodium, glucose and phosphate.
2. All experiments were carried out before and after the intravenous administration of phlorhizin [7 mg (15 μmol)/kg] with a sustaining infusion of the same dose/h. Thirteen dogs were studied during hydropenia (group I) and six dogs in the volume-expanded state (group II).
3. In the proximal tubule, phlorhizin significantly reduced sodium reabsorption in hydropenic dogs, but had no effect in volume-expanded dogs. Proximal tubular glucose reabsorption was completely inhibited by phlorhizin in both groups, but no significant change in phosphate reabsorption was observed.
4. Fractional glucose excretion in the urine reached 83–89% after phlorhizin, values significantly less than 100%, suggesting a residual reabsorption of glucose in a more distal segment or in deep nephrons. The changes in fractional excretion of sodium and phosphate were significantly correlated.
5. The effect of phlorhizin on both sodium and glucose reabsorption in the proximal tubule in hydropenic dogs suggests the existence of a co-transport mechanism, whereas the absence of an effect on sodium transport in volume-expanded dogs despite complete inhibition of glucose reabsorption indicates the existence of a sodium-independent component of net proximal tubular glucose transport.
6. Absence of the effect of phlorhizin on proximal tubular phosphate transport in the face of a significant reduction in sodium reabsorption implies that the reciprocal relationship between glucose and phosphate transport could be masked by the changes in sodium transport. Thus the sodium-phosphate transport relationship may prevail over that of glucose-phosphate in the proximal tubule.
Clonidine and Sympathetic Activity during Sleep
Authors: Maling T. J. B. , Dollery C. T. , Hamilton C. A. 
Published: August 2015

1. Blood pressure, heart rate, plasma noradrenaline and electroencephalographic variables were measured simultaneously during sleep in five healthy males before and after slow-release clonidine (300 μg orally) or placebo.
2. The blood pressure fall during sleep correlated significantly with the depth of sleep.
3. Clonidine significantly reduced systolic blood pressure during sleep and profoundly reduced total paradoxical sleep duration.
4. Plasma noradrenaline declined progressively during the sleep period and concentrations were significantly lower after clonidine compared with placebo.
Isolation of a Renal Thiol Protease that Activates Inactive Plasma Renin
Authors: Slater Eve E. , Gounaris Anne D. , Haber E. 
Published: August 2015

1. A thiol protease with properties similar to those of cathepsin B (EC 3.4.22.1) has been isolated and purified from human renal cortex.
2. This enzyme can generate renin activity from renin-suppressed and anephric human plasma at pH 5·5.
3. The renin activity thus generated is inhibited completely by antibody to purified human renal renin. This activation therefore represents the release of inactive renin.
Plasma Noradrenaline Correlates with α-Adrenoreceptor-Mediated Vasoconstriction and Blood Pressure in Patients with Essential Hypertension
Authors: Kiowski W. , Van Brummelen P. , Bühler F. R. 
Published: August 2015

1. The relationships between plasma noradrenaline concentration at rest and blood pressure, as well as increase in forearm blood flow in response to a brachial artery infusion of the α-adrenoreceptor-blocking agent phentolamine, were investigated in hypertensive and normotensive subjects of similar age.
2. In 44 hypertensive patients plasma noradrenaline correlated with systolic, diastolic and mean blood pressures, but no difference in the mean plasma noradrenaline concentration was found.
3. In 11 patients and 14 normotensive subjects α-adrenoreceptor blockade resulted in a similar increase in forearm blood flow. Only in the patients, however, was this increase related to plasma noradrenaline and blood pressure.
4. In patients with established essential hypertension plasma noradrenaline can be considered to be a marker of α-adrenoreceptor-mediated vasoconstriction, which, in part, determines the height of the blood pressure.
Sympatho—Adrenal and Cardiovascular Response to Mental Stress and Orthostatic Provocation in Latent Hypertension
Authors: Hjemdahl P. , Eliasson K. 
Published: August 2015

1. Seven latent hypertensive patients and seven matched controls were subjected to standardized mental stress and orthostatic provocation.
2. Mental stress increased blood pressure by approximately 25%, heart rate by 25 beats/min, plasma glycerol by 50% and plasma cyclic AMP by 25% in both groups. Plasma glucose and renin activity were unchanged. Plasma noradrenaline and adrenaline were essentially unchanged during stress.
3. There was an insignificant tendency towards higher noradrenaline levels in latent hypertensive subjects and two of these subjects displayed an exaggerated noradrenaline response to standing.
4. Our results indicate that the physiological responses to mental stress are caused by selective neuronal activation, rather than by generalized sympatho-adrenal activation. Latent hypertension does not seem to be associated with adrenergic hyperactivity or receptor supersensitivity, except possibly in individual cases.