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Biomedical subjects

J C Frolich

Publications and source records attributed to J C Frolich.

At least 19 recordsLinked to original sources
PubMed2001

Availability of medicines in the European Union: results from the EURO-Medicines project.

OBJECTIVE: There is at present no comprehensive directory of medicines available in European countries. Such a directory would be valuable to policy analysts, clinicians, regulatory agencies, pharmaceutical companies and consumer groups. The aim of this project was to compile such a directory of all medicines marketed in each of the European Union member countries. METHODS: Lists of medicines for each country, compiled from several national sources, classified by Anatomical-Chemical-Therapeutic (ATC) code. Census date was late 1998. RESULTS: A comprehensive directory was created using data from 14 of the 15 European Union countries. Numbers of trade names and of active ingredients varied widely, from Germany with 18,554 and 1,973, respectively, to Denmark with 1,915 and 1,016, respectively. In individual therapeutic areas, there were variations in the numbers of active ingredients available: the least variation between countries was in antineoplastic medicines (ATC code L, maximum number available in any country 101, minimum 60) and wider variation in alimentary (ATC code A, maximum 256. minimum 103) or cardiovascular (ATC code C, maximum 269, minimum 112). Only 7% of all the active ingredients were available in all the countries studied. The Scandinavian countries had the greatest proportion of active ingredients (60%) available in all other countries. Each country had a number of active ingredients available only in that country Italy had the largest number of these. CONCLUSIONS: The directory illustrates the wide variations in the availability of medicines across the European Union. The range of drugs available in each country represents differences in regulatory and market policies, as well as cultural and historic differences. This directory lends itself to many further analyses.

Data Collection↗
PubMed1996

Nitric oxide may mediate the hemodynamic effects of recombinant growth hormone in patients with acquired growth hormone deficiency. A double-blind, placebo-controlled study.

We studied the effects of recombinant growth hormone on systemic nitric oxide (NO) formation and hemodynamics in a double-blind, placebo-controlled trial in adult patients with acquired growth hormone deficiency. 30 patients were randomly allocated to either recombinant human growth hormone (r-hGH; 2.0 IU/d) or placebo for 12 mo. In the subsequent 12 mo, the study was continued with both groups of patients receiving r-hGH. In months 1, 3, 6, 9, and 12 of each year, urine and plasma samples were collected for the determination of urinary nitrate and cyclic GMP as indices of systemic NO production, and of plasma IGF-1 levels. Cardiac output was measured in months 1, 12, and 24 by echocardiography. r-hGH induced a fourfold increase in plasma IGF-1 concentrations within the first month of treatment. Urinary nitrate and cyclic GMP excretion rates were low at baseline in growth hormone-deficient patients (nitrate, 96.8+/-7.4 micromol/mmol creatinine; cyclic GMP, 63.6+/-7.1 nmol/mmol creatinine) as compared with healthy controls (nitrate, 167.3+/-7.5 micromol/mmol creatinine; cyclic GMP, 155.2+/-6.9 nmol/mmol creatinine). These indices of NO production were significantly increased by r-hGH, within the first 12 mo in the GH group, and within the second 12 mo in the placebo group. While systolic and diastolic blood pressure were not significantly altered by r-hGH, cardiac output significantly increased by 30-40%, and total peripheral resistance decreased by approximately 30% in both groups when they were assigned to r-hGH treatment. In the second study year, when both groups were given r-hGH, there were no significant differences in plasma IGF-1, urinary nitrate, or cyclic GMP excretion, or hemodynamic parameters between both groups. In conclusion, systemic NO formation is decreased in untreated growth hormone-deficient patients. Treatment with recombinant human growth hormone normalizes urinary nitrate and cyclic GMP excretion, possibly via IGF-1 stimulation of endothelial NO formation, and concomitantly decreases peripheral arterial resistance. Increased NO formation may be one reason for improved cardiovascular performance of patients with acquired hypopituitarism during growth hormone therapy.

Adult↗
PubMed1996

Urinary NO3- excretion as an indicator of nitric oxide formation in vivo during oral administration of L-arginine or L-name in rats.

1. Endothelium-derived nitric oxide (NO), a major modulator of vascular tone, is synthesized from the terminal guanidino nitrogen of L-arginine. This reaction is inhibited by analogues of L-arginine, such as N-nitro-L-arginine methyl ester (L-NAME). Many of the biological effects of NO are mediated by the second messenger cGMP. NO is rapidly oxidized to NO3-, which, like cGMP, is eliminated via excretion into the urine. In a placebo controlled study, we investigated whether oral bolus administration of L-arginine and L-NAME affects the urinary excretion rates of NO3- and cGMP in Munich Wistar Frommter (MWF) rats. 2. Twenty MWF rats were kept in metabolic cages and received L-arginine (3 g/kg bodyweight), L-NAME (50 mg/kg), or placebo (0.9% saline) in randomized order. Urine samples were sequentially collected for 10 h and analysed for creatinine, NO3- and cGMP. 3. L-Arginine inducted a slight, but prolonged increase in urine flow, whereas L-NAME induced an early, transient increase in urine flow which was followed by a decrease. Creatinine clearance decreased by 65% after L-NAME, but was not affected by L-arginine or placebo. 4. Urinary NO3- and cGMP excretion rates transiently increased after L-arginine (NO3-: + 29%; cGMP: +16%) for 4-5 h, whereas L-NAME induced an immediate, pronounced and lasting inhibition of urinary NO3- and cGMP excretion (NO3-: -76%; cGMP: -46%). Urinary NO3- and cGMP excretions were significantly correlated (r = 0.755; P < 0.001). 5. Urinary excretion rates of NO3- and cGMP, expressed as mu mol/h, were correlated to urine flow (mL/h; r = 0.617 and 0.649, respectively; both P < 0.05), whereas after correction by urinary creatinine (mu mol/mmol creatinine) no correlation with urine flow was observed, indicating that these excretion rates were independent of renal excretory function. Thus we conclude that changes in the urinary excretion rates of NO3- and cGMP represent changes in NO production rates in vivo when expressed in relation to urinary creatinine. Urinary NO3- and cGMP excretion is modulated by acute NO synthase inhibition or substrate provision.

Animals↗
PubMed1991

Long term observations in a patient with pseudohypoaldosteronism.

This paper describes a patient with severe pseudohypoaldosteronism (PHA) for over 12 years. The patient presented at 10 days of age with a serum sodium of 118 mEq/l and potassium of 12 mEq/l. After failing to maintain normal fluid and electrolyte status with standard therapy, including maximal mineralocorticoid stimulation, he was given a special formula containing minimal potassium plus salt supplements which normalized his electrolyte status. However, when he was 4.5 years of age, an acute gastrointestinal illness led to severe volume depletion, hyperkalemia, and cardiopulmonary arrest. This resulted in significant neurological impairment. At 12.5 years of age, the patient continues to require massive sodium supplements and his diet contains less than 0.5 mEq/kg potassium daily; his height and weight are at the 95th percentile, thus demonstrating that normal growth may be achieved with strict dietary manipulation in a patient with persistent, severe PHA. Serial studies to further define the lesion in this patient have demonstrated: (1) normal binding of aldosterone to aldosterone binding globulin (5.1% bound); (2) normal mineralocorticoid "activity"; (2) suppressible renin and aldosterone levels; (4) increased prostaglandin excretion (3.15 micrograms/g creatinine); (5) lack of benefit of prostaglandin inhibition with indomethacin; (6) normal proximal tubule function (CNa + CH2O = 18.0 ml/100 ml glomerular filtration rate; (7) impaired distal tubule function (CH2O/CNa + CH2O = 79.8%) during water diuresis.

Aldosterone↗
PubMed1991

Metabolism of cysteinyl leukotrienes by the isolated perfused rat kidney.

The metabolism of cysteinyl leukotrienes by the isolated perfused rat kidney was investigated. For this purpose LTC4, LTD4 or LTE4 were studied in separate experiments. The isolated perfused rat kidney metabolized all cysteinyl leukotrienes to the final metabolite N-acetyl-LTE4. In the presence of 5% albumin 50% of LTC4 was metabolized to LTD4 (22%), LTE4 (15%) and N-acetyl-LTE4 (13%) within 60 min. Excretion of radioactivity into urine was less than 1%. In contrast, in the absence of albumin, LTC4 was completely metabolized within 45 min to N-acetyl-LTE4, the sole and final metabolite of LTC4 found in the perfusion medium as well as in urine. After 60 min 19% and 42% of total radioactivity were found in the perfusion medium and in urine, respectively. Isolated glomeruli metabolized LTC4 to LTD4 and to LTE4 but not to N-acetyl-LTE4 at a rate comparable to the rate observed by the isolated perfused kidney in the absence of albumin. In contrast to isolated glomeruli isolated tubuli metabolized LTE4 to N-acetyl-LTE4 at a rate comparable to that observed by the isolated perfused kidney in the absence of albumin. The present study shows that the isolated perfused rat kidney metabolizes cysteinyl leukotrienes to the sole and final metabolite N-acetyl-LTE4. In the presence of albumin metabolism is slowed down and excretion of N-acetyl-LTE4 into urine is prevented.

Animals↗
PubMed1980

Interaction of indomethacin and ibuprofen with lithium in manic patients under a steady-state lithium level.

The clinical effects of prostaglandin synthesis inhibitors were studied in lithium treated manic patients. While indomethacin increased plasma lithium concentration, the effect of ibuprofen was inconsistent. Adverse reactions included tremors unrelated to changes in plasma lithium levels; nausea and drowsiness in 1 ibuprofen treated patient possibly related to the slight increase in plasma lithium, and a syndrome consisting of running nose, malaise and generalized body aches in 1 indomethacin treated patient. Our findings are in support of an important interaction between prostaglandin synthesis inhibitors and especially indomethacin and lithium, which may result in an increase in adverse reactions.

Adult↗
PubMed1978

Relation between plasma concentration of indomethacin and its effect on prostaglandin synthesis and platelet aggregation in man.

The dose and plasma levels of indomethacin correlated with inhibition of prostaglandin synthesis as measured both by urinary excretion of the major metabolite of prostaglandin E2 (PGE-M) and by the release of prostaglandin E2 from thrombin-stimulated platelets. Considerable intersubject variability was observed in the suppression of PGE-M excretion. In some patients 37.5 mg indomethacin daily, usually considered subtherapeutic, caused suppression. Maximal suppression (greater than 90%) occurred in some after a daily dose of 75 mg, whereas 150 mg was required to achieve this level of inhibition in others. Suppression of the excretion of PGE-M by 60% occurred when the end of the dosage interval plasma levels of indomethacin were in the range 0.05 to 0.3 microgram/ml, which implies that a somewhat higher average steady-state concentration during the dosage interval was required to achieve this effect. A similar degree of inhibition of the release of PGE2 on thrombin-stimulated platelets was associated with the same range of plasma levels. Upon discontinuation of the drug, the levels of indomethacin in plasma decreased exponentially; inhibition of the release of PGE2 from platelets by indomethacin declined linearly with time and in parallel with the logarithm of the diminishing plasma levels.

Adult↗
PubMed1978

Redistribution of intrarenal blood flow following ADH administration: lack of inhibition by blockade of prostaglandin in cyclooxygenase.

The effect of prostaglandin synthesis inhibition on the redistribution of renal cortical blood flow in response to antidiuretic hormone (ADH) was examined using radioactive microspheres in water loaded, thiopental-anesthetized dogs. Microsphere injections were made during a control and an ADH infusion period (0.35 mU/kg/min following a 20 mU/kg bolus) both before and after indomethacin pretreatment (8 mg/kg intravenously). Urinary prostaglandin E2 (PGE2) excretion in each period was measured by gas chromatography-mass spectrometry. ADH caused a marked redistribution of flow toward inner cortical zones from 19 +/- 1 to 25 +/- 2 ml/min (mean +/- SE, p less than 0.01). Fractional flow to inner zones was also significantly increased. Indomethacin pretreatment had no effect on the ADH-induced redistribution (17 +/- 2 vs. 24 +/- 2 ml/min, p less than 0.01), although urinary PGE2 excretion was suppressed by indomethacin by 60%. It is concluded that prostaglandins do not mediate the redistribution of intrarenal blood flow accompanying ADH administration.

Animals↗
PubMed1977

Prostaglandins and renin release: I. Stimulation of renin release from rabbit renal cortical slices by PGI2.

Prostaglandins have been shown to be involved in the mechanism of renin secretion in a variety of situations. Both arachidonic acid and prostaglandin endoperoxide have been shown to release renin from cortical slices and to be converted to PGI2 by cortical microsomes. In the present studies PGI2 was found to cause a time dependent increase in renin release from rabbit renal cortical slices, a system isolated from any indirect effects that result from the administration of prostaglandins in vivo. The stimulation was linear up to 30 minutes and effective over a range of concentrations from 10(7 M to 10(-5) M. At similar concentrations 6-keto-prostaglandin F1alpha was not active on these slices. Thus, it is proposed that PGI2 exerts a direct effect on the release of renin from cortical cells and may be the mediator of arachidonate or prostaglandin endoperoxide stimulated renin secretion.

Animals↗
PubMed1976

Quantifications of the major urinary metabolite of the E prostaglandins by mass spectrometry: evaluation of the method's application to clinical studies.

Measurement of 7alpha-hydroxy-5,11-diketotetranoprostane-1,16-dioic acid, (PGE-M), the major urinary metabolite of prostaglandin E1 and E2 in man provides a useful indicator to monitor prostaglandin biosynthesis. For quantitative analysis of this prostaglandin metabolite and the stable-isotope dilution techniqe of selected ion monitoring (SIM) is employed using gas-liquid chromatography-mass spectrometry. The preparation of the bis(D3-methyloxime), bis-methyl ester of PGE-M containing a tritium tracer in position 2 which was used as internal standard for the SIM method is described. The synthesis of this internal standard includes the biosynthetic conversion of 11-hydroxy-9,15-diketoprostanoic acid to PGE-M by the rabbit. The intra-assay coefficient of variation of this SIM method ranged between 4.0 to 6.7 percent. The recovery of authentic, underivatized PGE-M added to urine was 93 +/- 3% (mean +/- SEM, n=17). The levels of PGE-M excreted in urine were higher (p less than 0.001) in males than in females (15.2 +/- 1.9 mug/24 hours (n=24) and 3.3 +/- 0.3 mug/24 hours (n=17), respectively. These levels were in close agreement with values published previously. No significant difference in excretion of PGE-M between the sexes was observed in the pre-pubertal age-grou (male: 2.9 +/- 0.8 mug/24 hours, n=5; female: 3.1 +/- 0.9 mug/24 hours, n=5) or in the age-group of 45-80 years (male: 9.3 +/- 1.1 mug/24 hours, n=21; female: 7.3 +/- 0.9 mug/24 hours, n=12). The amount of PGE-M excreted decreased significantly after administration of indomethacin or acetyl salicylic acid in therapeutic doses. The concomitant reduction of the urinary excretion of PGE-M (68 to 85% decrease) and prostaglandin E (73 to 100% decrease) after indomethacin treatment in each case (n=8) is evidence that a diminished urinary PGE-M output reflects a decrease in prostaglandin E biosynthesis.

Adolescent↗
PubMed1976

Prostaglandins are overproduced by the kidneys and mediate hyperreninemia in Bartter's syndrome.

In summary, the cardinal features of the syndrome of renal juxtaglomerular hyperplasia include overproduction of plasma renin activity, elevation of plasma angiotensin II concentration, elevation of aldosterone secretion and of plasma aldosterone concentration, hypokalemic alkalosis, and a resistance of arterioles to the pressor action of angiotensin II and norepinephrine. In the present studies, elevation of urinary PGE2 but not of PGF2alpha has been demonstrated. Inhibition of prostaglandin synthetase with indomethacin or ibuprofen has been shown to decrease plasma renin activity, and plasma aldosterone concentration and secretion rate, leading to a positive potassium balance and restoration of normal plasma potassium. The inhibitors decreased and glomerular filtration rate, and induced sodium retention. The results indicate that overproduction of PGE by the kidneys is a cardinal feature, but not necessary the primary one, in the pathogenesis of this syndrome.

Adolescent↗