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  • 1
    ISSN: 1434-0879
    Keywords: Kidney stone analyses ; Sex and age ; Mineral metabolism data ; Serum and urine ; Activity products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stone analyses (kidney, upper urinary tract) of the department of Urology, University of Erlangen, from a four-year-period (1974–1977) have been recorded with emphasis to stone composition, sex and age of the pertinent stone forming patients. During this time period there were no substantial changes as regards the per cent frequency of the various stone types. The most frequent type was calcium oxalate (CaOx), followed by uric acid, calcium phosphate (CaP), struvite and cystine. Stone analyses were mostly requested for patients between 46 and 55 years of age. Stone incidence in our clinic is calculated to be 1.22 times higher in males than females, especially beyond 36 years of age. The frequency peaks are: pure (=100 per cent) CaOx 36–45 years; CaOx with additional mineral phases (mostly CaP) 46–55 years; uric acid 56–65 years; CaP 26–35 years. From those patients who underwent further investigations in searching for metabolic abnormalities serum concentrations, urine mineral clearances in fasting urine samples, and activity products of stone forming mineral phases in sequentially collected specimens from 24 h and 2 h fasting urine had been measured and compared with values from healthy control subjects. In urolithiasis (idiopathic) there is a normal parathyroid hormone blood level, a generally lower serum inorganic phosphate and magnesium concentration. In pure (=100 per cent) CaOx and uric acid lithiasis serum uric acid and creatinine are higher than in controls, urine pH and calcium clearance in some groups are different too. Clearances of magnesium, uric acid, phosphate, sodium are within normal limits in urolithiasis. When expressing the propensity to form stones in terms of activity products, then only uric acid lithiasis deviates substantially from normal. All other stone types differ only slightly or not at all from each other and controls respectively. It is concluded that 1) in our geographic region the various stone types prevail in different age periods; 2) there are distinct alterations of parameters of mineral metabolism in urolithiasis; 3) measuring urine clearances may lead to assume falsely normal mean urine excretion of stone forming constituents.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1912
    Keywords: Theophylline ; Isoprenaline ; Calcium ; Ouabain ; Positive inotropic effect ; c-AMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of theophylline (3×10−5 M–5×10−3 M), isoprenaline (10−6 M), excess calcium (7.2 mM) and ouabain (3×10−7 M) on force of contraction and c-AMP content were studied in electrically driven (frequency 3 Hz) left auricles isolated from guinea pigs pretreated with reserpine. 1. Theophylline (2×10−3 M) increased c-AMP consistently. The theophylline-induced increase in c-AMP proceeded very rapidly. It became significant after an incubation period of 5 s, reached its peak after 5 min and then remained stable. The positive inotropic effect of theophylline also developed very rapidly, reached its peak after 1 min and then declined. The increase in force of contraction corresponded to the increase in c-AMP, but the decline of the positive inotropic effect occurred while c-AMP remained elevated. 2. The concentration-response curves for the theophylline-induced increases in c-AMP and force of contraction were virtually parallel at concentrations up to 2×10−3 M. 3. Washout of the effects of theophylline on c-AMP and force of contraction was also similar. Complete reversal occurred within 15 min. 4. The effects of theophylline on c-AMP and force of contraction were not affected by 10−7 M propranolol added 30 min before theophylline. 5. Isoprenaline (10−6 M) increased c-AMP and force of contraction to approximately the same extent upon incubation for up to 30 min. 6. Ouabain (3×10−7 M) or the elevation of the extracellular calcium concentration to 7.2 mM increased the force of contraction without producing a detectable increase in c-AMP. 7. It is concluded that the theophylline-produced increase in force of contraction may be the result of an increase in c-AMP and a subsequent increase in slow inward current. This effect may be counteracted by a direct, c-AMP independent effect of theophylline on intracellular calcium stores which could account for the decline of the positive inotropic effect of theophylline during prolonged exposure and at high concentrations. 8. The present data also support the view that the positive inotropic effect of isoprenaline is mediated by c-AMP, whereas the effects of ouabain and excess calcium on force of contraction appear to be independent of the c-AMP system.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1912
    Keywords: Phenylephrine in the presence of propranolol ; Positive inotropic effect ; c-AMP ; Time to peak force ; Relaxation time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of phenylephrine on the shape of the contraction curve and on the cyclic adenosine 3′,5′-monophosphate (c-AMP) content were studied in electrically driven (frequency 0.2 Hz) cat papillary muscles. All experiments were done in the presence of 1 μM propranolol in order to minimize interference from β-adrenoceptors. 1. Phenylephrine increased the force of contraction in a concentration-dependent manner. Maximal effects (about 200% of control) occurred at 30 μM phenylephrine. 2. The positive inotropic effect (PIE) of phenylephrine was antagonized by phentolamine. Phentolamine, 5μM, produced a parallel shift of the concentration-response curve for the PIE of phenylephrine by about two log units to the right. 3. The PIE of 30 μM phenylephrine occurred without any detectable increase in the c-AMP levels of the preparations. 4. The PIE of 30μM phenylephrine developed about three times more slowly than the PIE of an equieffective concentration of isoprenaline. 5. The PIE of phenylephrine was accompanied by significant, concentration-dependent increases in both time to peak force and relaxation time. 6. It is concluded that the PIE of phenylephrine in the presence of propranolol is mediated mainly by a stimulation of α-adrenoceptors. It is unlikely to be related to an increase in c-AMP. With respect to time course and influence on the shape of the contraction curve it is qualitatively different from the effects of β-adrenoceptor stimulation. These data are taken to support the hypothesis that the mechanical effects of α-and β-adrenoceptor stimulating agents on the heart are produced by different mechanisms.
    Type of Medium: Electronic Resource
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