Can complementary medicine enhance doctor-patient communication skills? Insights from an international medical student project.

INTRODUCTION: Communication is an essential component of patient care, and although medical schools provide training on this topic, patients and physicians alike express the need to improve their communication skills. An international medical student collaboration explored whether complementary medicine (CM) has the ability to further enhance patient-doctor communication. METHODS: Twenty-two medical students, nine mentors and two public representatives from Israel and Germany participated in this 18-month international group project. The goal was to explore CM methods that could enrich doctor-patient communication in several aspects. The group eventually chose to focus on four CM modalities, which included Chinese medicine; Mind-Body medicine; Touch therapies; Mindfulness and Herbal medicine. One workshop took place in Haifa and two workshops in Berlin, with continued inter-group work in-between. The workshops included interactive group formats such as "World Café", self-experience sessions in CM, working in small groups and delivering presentations to the entire group. RESULTS: Besides benefitting from cultural exchange and networking, students learned various aspects of CM, with a particular focus on their relevance for enriching their communication skills. The main CM aspects that were highlighted included patient characterization in the context of Chinese medicine diagnosis, mindfulness, anamnesis regarding herbal use, and a physical exam based on concepts from touch therapies. Students summarized and condensed their observations into five educational modules, which are available online: http://www.b-zion.org.il/pages_e/6683.aspx. CONCLUSION: The cultural exchange and explorative process in this international medical student collaboration led to insights regarding the potential contribution of CM to patient-doctor communication. The outcomes of this international collaboration, specifically the educational modules it produced, should be further explored by medical schools, and assessed in clinical trials.

The simultaneous measurement of plasma-aldosterone- and -renin-concentration allows rapid classification of all disorders of the renin-aldosterone system.

OBJECTIVE: The determination of the plasma aldosterone (PAC) to the plasma renin concentration (PRC) ratio is an accepted screening tool for primary hyperaldosteronism (PHyperA). DESIGN: To assess the diagnostic significance of this ratio for other disorders of the renin-aldosterone-system (RAS), we examined 60 patients with different adrenal diseases, 32 patients with essential hypertension and 76 normotensive healthy volunteers. The aldosterone (pmol/L) and renin (mU/L) concentrations were measured in one plasma sample by an automated chemiluminescence assay (Nichols Advantage). RESULTS: Patients with PHyperA (n=31) had a PAC/PRC ratio between 105 and 2328 and could be distinguished without overlap from the essential hypertension group (ratio: range 2.7-49) and normal healthy volunteers (ratio: range 0.9-71). Fourteen patients with primary hypoaldosteronism showed low PAC/PRC ratios (range 0.21-0.98) and low PAC values (range: 42-100). Seven patients with secondary hypoaldosteronism had normal PAC/PRC ratios (range 2.8-23.2) and low PAC values (range: 42-116). Eight patients with secondary hyperaldosteronism had normal PAC/PRC ratios (range 7.8-67.9) and elevated PAC values (range: 803-2917). The graphic presentation of these data allowed the differentiation of all major disorders of the RAS. CONCLUSIONS: The measurement of PAC/PRC ratios using this automated system provides a sensitive and rapid screening method for PHyperA. Moreover, the measurement of both the PAC and the PAC/PRC ratio allows differentiation of other disorders of the RAS.

Acquired von Willebrand syndrome in respiratory extracorporeal life support: a systematic review of the literature.

BACKGROUND AND OBJECTIVE: Venovenous extracorporeal membrane oxygenation (VV ECMO) and extracorporeal CO2 removal (ECCO2R) are increasingly used in the management of severe respiratory failure. With bleeding complications being one of the major risks of these techniques, our aim in this systematic review was to assess the available literature on acquired von Willebrand syndrome (AvWS) and extracorporeal support. AvWS has previously been associated with bleeding and shear stress. DESIGN AND DATA SOURCES: A systematic review, using Medline via PubMed, was performed to identify eligible studies up to January 2017. RESULTS AND CONCLUSION: The prevalence of AvWF among patients on VV ECMO or ECCO2R is high, but only a limited number of studies are reported in the literature. AvWS testing should be performed, including vWF multimer analysis, vWF activity and vWF antigen concentration. The extent to which vWF contributes to bleeding during ECMO, or how much changes in ECMO management can influence high molecular weight vWF multimer levels, cannot be answered from the currently available evidence and there remains a need for future studies.

Free fatty acids increase androgen precursors in vivo.

CONTEXT: There is considerable evidence that metabolic factors such as insulin resistance may induce hyperandrogenemia in polycystic ovary syndrome. However, other metabolic factors such as free fatty acids (FFAs) may also contribute to androgen excess. OBJECTIVE: The objective was to study effects of FFAs on adrenal production of androgen precursors in vivo. DESIGN AND PARTICIPANTS: We investigated eight healthy young men, because male individuals produce the androgen precursors dehydroepiandrosterone (DHEA), DHEA sulfate, and androstenedione predominantly in the adrenal gland. A randomized controlled crossover trial was performed. INTERVENTION: After a 10-h overnight fast, 20% lipid/heparin or saline/heparin infusion was given at a rate of 1.5 ml/min. Four hours after start of lipid infusion, a euglycemic hyperinsulinemic clamp was performed. MAIN OUTCOME MEASURES: DHEA, androstenedione, 17-OH-progesterone, testosterone, estrone, LH, FSH, ACTH, and cortisol were measured. RESULTS: The adrenal androgen precursors DHEA and androstenedione showed a circadian decline during saline/heparin infusion (P < 0.05 vs. baseline, respectively), whereas no significant changes were observed during lipid/heparin infusion (P = not significant vs. baseline, respectively). Correspondingly, DHEA and androstenedione values were significantly elevated during lipid compared with saline infusion (P < 0.05, respectively), and areas under curve of both androgen precursors were significantly increased with lipid compared with saline infusion. Notably, all changes were detected before induction of insulin resistance. CONCLUSIONS: This study demonstrates that FFAs increase production of androgen precursors in vivo in men. These data tentatively suggest that hyperandrogenemia in polycystic ovary syndrome may be induced, at least in part, by elevated FFAs.

Effect of smoking cessation counseling within a randomised study on early detection of lung cancer in Germany.

INTRODUCTION: In the German lung cancer screening trial LUSI, smoking cessation counseling (SCC) was offered to all participants at time of randomization, and smoking habits were asked for within annual questionnaire inquiries. We analyzed the smoking habits of the participants within the first 2 years of follow-up and especially the potential effect of the SCC on these habits. MATERIALS AND METHODS: We used the smoking data of the initial inquiry on which the decision on invitation to the study was based, the socio-economic data of the questionnaire filled-in at time of randomization, the psycho-social data obtained during the SCC, and the annual questionnaire data of the first two annual follow-up screening rounds. RESULTS: Smoking prevalence decreased in the entire cohort significantly by 4 %, whereby the decrease was with 4.5 % statistically not significantly higher in the control arm than in the screening arm with 3.4 %. The decline was much stronger in the subgroup of attendees to stop-smoking counseling and mounted up therein to 10 %. In some participants, an increase of readiness to quit smoking was observed during the counseling hour, but did not show effects on smoking status 2 years later. DISCUSSION: We did not see a tendency to increased smoking among participants of the intervention arm or the entire study. The decline of smoking prevalence among the attendees of the counseling might be due to self-selection. Since the issue of effectiveness of smoking cessation counseling is important, further research with randomization into offering counseling or no intervention should be taken into consideration.

Glucagon inhibits ghrelin secretion in humans.

OBJECTIVE: It is well known that i.m. glucagon administration stimulates GH and cortisol release in humans, although the mechanisms are unclear. These effects are similar to those described for ghrelin on somatotroph and corticotroph function. The aim of the present study was to investigate the role of ghrelin in mediating the stimulatory effects of glucagon and to evaluate the effect of glucagon on ghrelin secretion. DESIGN AND METHODS: We studied the endocrine and metabolic response to i.m. glucagon administration in 24 subjects (14 men, 10 women; age 19-65 years; body mass index, 25.3 +/- 1 kg/m(2)), who were shown to have an intact anterior pituitary function as evaluated before enclosure. RESULTS: Serum ghrelin concentrations fell significantly at 30, 60, 120 and 180 min after glucagon administration (means +/- s.e.m.; baseline, 377.9 +/- 34.5 pg/ml; nadir, 294.6 +/- 28.3 pg/ml (60 min); P < 0.01). Conversely, i.m. glucagon elicited an increase in GH (baseline, 1.5 +/- 0.4 microg/l; peak, 14.2 +/- 2.7 microg/l (180 min); P < 0.01) and cortisol concentrations (baseline, 452.6 +/- 35.2 nmol/l; peak, 622.1 +/- 44 nmol/l (180 min); P < 0.01). The changes in ghrelin concentration at both 120 and 180 min were still significant after correction for glucose and insulin (P < 0.05). CONCLUSIONS: We show that i.m. glucagon decreases ghrelin significantly. Therefore, the already known stimulatory effects of i.m. glucagon on cortisol and GH are not mediated by a change in ghrelin concentrations. The mechanisms underlying the ghrelin suppression after i.m. glucagon are unlikely to include glucose or insulin variations and need to be further elucidated.

Diagnosis and therapy surveillance in Addison's disease: rapid adrenocorticotropin (ACTH) test and measurement of plasma ACTH, renin activity, and aldosterone.

The rapid ACTH injection test is an indirect screening test for adrenocortical insufficiency. As a supplement to this test, we evaluated the practicability of single measurements of plasma cortisol, ACTH, aldosterone, and PRA as a definitive diagnostic test of primary adrenocortical insufficiency (PAI). We also tested the value of PRA measurements during treatment with hydro- and fludrocortisone (HC and FC) as a guide for correct mineralocorticoid substitution. In 45 patients with PAI, results of the rapid ACTH test and single measurements of the four hormones (all tests between 0800-0900 h) were compared. Single hormone measurements were also made in 55 normal subjects and 46 patients with pituitary disease (cortisol and ACTH only), most of them with mild to severe secondary adrenocortical insufficiency (SAI). The rapid ACTH test was abnormal in 100% of 41 patients with PAI tested. Plasma ACTH, PRA, and the ratios of ACTH/cortisol and PRA/plasma or urinary aldosterone were clearly elevated in 100% of the patients with PAI. The ACTH/cortisol ratio also distinguished 100% of patients with PAI from those with SAI, but not always control subjects from those with SAI. Thus, dynamic tests (CRH or insulin tests) are indicated if SAI is suspected. PAI and involvement of zona fasciculata and glomerulosa function can be diagnosed with high reliability by measuring cortisol, ACTH, aldosterone, and PRA either together with the rapid ACTH test or later, after a short interval of steroid substitution. PRA measurements during treatment with HC and FC correlated better with the mineralocorticoid dose than plasma potassium and sodium levels. PRA measurement is a valuable guide for FC replacement therapy. It should be titrated into the upper normal range to avoid under- and overtreatment.

Dose-response relationships between plasma adrenocorticotropin (ACTH), cortisol, aldosterone, and 18-hydroxycorticosterone after injection of ACTH-(1-39) or human corticotropin-releasing hormone in man.

The effects of sc injections (at 1500 h) of increasing amounts of synthetic human ACTH-(1-39) (1.25-30 micrograms) on plasma ACTH, cortisol, aldosterone, and 18-hydroxycorticosterone were compared with those of iv injections of 30 and 100 micrograms synthetic human CRH in nine normal men. Five micrograms of ACTH, sc, was the lowest dose that significantly increased plasma levels of the three steroids. CRH (30 micrograms, iv) increased plasma cortisol and 18-hydroxycorticosterone, but not aldosterone, while 100 micrograms CRH also raised aldosterone secretion. The dose-response curve (peak plasma ACTH level vs. maximum increment of plasma cortisol within the first hour) was initially very steep. Plasma ACTH levels between 50 and 60 ng/L (11-13 pmol/L) stimulated cortisol to almost 80% of the maximal increment obtained with plasma ACTH levels above 300 ng/L (greater than 66 pmol/L). This dose-response relationship is similar to that found in clinical tests of the pituitary-adrenal axis (insulin test, metyrapone test). The effects of plasma ACTH released by CRH on cortisol secretion were not significantly different from those of injected ACTH. Our results argue against the hypothesis that the effect of CRH on steroid secretion is mediated or modulated by POMC-derived peptides other than ACTH.

Effects of incremental infusions of atrial natriuretic factor on aldosterone, renin, and blood pressure in humans.

To evaluate the physiological effects of human atrial natriuretic factor-(99-126) (ANF), we infused ANF, 0.1, 0.3, and 1.0 micrograms/min, or placebo for 125 minutes on different days into six sodium-deprived normal men. During the last 45 minutes of infusion, angiotensin II, 6 ng/kg/min, was infused. Blood pressure, heart rate, plasma concentrations of ANF, aldosterone, and cortisol, and plasma renin activity (PRA) were measured before and during infusion. Steady state mean plasma ANF levels during infusion were 26.2 (placebo), 68.8 (0.1 micrograms ANF/min), 221 (0.3 micrograms ANF/min), and 648 pg/ml (1.0 microgram ANF/min). Systolic blood pressure fell significantly (with 1.0 microgram ANF/min), and diastolic pressure tended to rise in a dose-dependent manner, while heart rate was unchanged. PRA and plasma aldosterone fell during ANF infusion in a dose-dependent manner (significant with 0.3 and 1.0 microgram ANF/min infused). The blood pressure-raising and aldosterone-stimulating effects of angiotensin II were blunted by ANF (significant only with 1.0 microgram ANF/min). It is concluded that effects of ANF on blood pressure and the renin-aldosterone system occur with plasma ANF levels close to the physiological range, as well as with slightly elevated ANF levels, as observed in congestive heart failure and renal insufficiency.

Primary hyperaldosteronism without suppressed renin due to secondary hypertensive kidney damage.

Primary hyperaldosteronism is characterized by high plasma and urinary aldosterone and suppressed PRA. Renin suppression is due to aldosterone-dependent sodium retention and mild extracellular volume expansion. We observed three patients with primary hyperaldosteronism, severe refractory hypertension, and normal to high normal PRA levels whose aldosterone/renin ratios were still elevated because of disproportionately high aldosterone levels. All available medical data on the patients as well as publications on the aldosterone/renin relationship in primary hyperaldosteronism were reviewed to explain the unusual findings. In one patient, histologically proven renal arteriolosclerosis was the probable cause of the escape of PRA from suppression by an aldosterone-producing adenoma. In the other two patients, hypertensive kidney damage due to primary hyperaldosteronism was the most likely explanation for the inappropriately high PRA, as in patient 1. All patients had high normal or slightly elevated serum creatinine levels and responded to 200 mg spironolactone/day with increased serum creatinine and hyperkalemia. Hyperkalemia was probably due to a decreased filtered load of sodium and a spironolactone-induced decrease in mineralocorticoid function. Two patients were cured of hyperaldosteronism by unilateral adrenalectomy but still need some antihypertensive therapy, whereas one patient has probable bilateral adrenal disease, with normal blood pressure on a low dose of spironolactone. In patients with severe hypertension due to primary hyperaldosteronism, PRA can escape suppression if hypertensive kidney damage supervenes. An increased aldosterone/PRA ratio is still useful in screening for primary hyperaldosteronism. These patients may respond to spironolactone therapy with a strong increase in serum creatinine and potassium. Early specific treatment of primary hyperaldosteronism is therefore indicated, and even a patient with advanced hypertension will profit from adrenalectomy or cautious spironolactone treatment.

The role of atrial natriuretic factor [alpha-human ANF-(99-126)] in the hormonal and renal adaptation to sodium deficiency.

Atrial natriuretic factor (ANF) inhibits renin and aldosterone secretion and enhances natriuresis in short term experiments. For studying the role of ANF in the chronic hormonal and renal adaptation to sodium restriction, we infused alpha-human ANF iv at a low dose (0.15-0.2 microgram/min) for 6 days into five normal male volunteers on a low sodium diet (LS; 15 mmol Na+/day) to mimic ANF levels observed in a preceding high sodium period (HS; 250 mmol/day). Endocrine (ANF, PRA, and aldosterone) and renal parameters (urine volume and urinary sodium) and plasma and urinary cGMP were measured and compared to sodium restriction without ANF infusion. At the end of HS and LS periods, the response of plasma aldosterone to angiotensin-II infusion was tested. ANF infusion prevented the fall in plasma ANF from a mean of 17.7 on HS to 7 pmol/L on LS by raising the level to 16.1 pmol/L. Cumulative negative sodium balance and the rise in renin activity and aldosterone were almost identical in both parts of the experiment. There was a transient diuretic and mild hypotensive effect of ANF. Plasma and urinary cGMP rose only transiently during ANF infusion despite constantly elevated ANF levels, suggesting that the effect of ANF was blunted under long term conditions by receptor down-regulation or other mechanisms inhibiting cGMP formation. Chronic ANF infusion did not blunt the enhanced aldosterone response to angiotensin-II in the LS state. ANF does not seem to play a major role in the long term renal and hormonal adaptation to dietary sodium restriction.

Metabolism of dexamethasone in the human kidney: nicotinamide adenine dinucleotide-dependent 11beta-reduction.

Recently, two distinct isoenzymes of 11beta-hydroxysteroid-dehydrogenase (11beta-HSD) have been cloned and characterized in several species: The isoenzyme 11beta-HSD-I is widely distributed, bidirectional, prefers NADP(H) and has a low substrate affinity. The isoenzyme 11beta-HSD-II seems to exclusively oxidize physiological glucocorticoids, uses NAD as cosubstrate, has high substrate affinity, and is only found in mineralocorticoid target tissues and the placenta. Synthetic steroids fluorinated in position 9, however, are rapidly reduced by human kidney cortex slices. We attempted to find out which isoenzyme is responsible for this unexpected reductase activity. We studied the 11beta-HSD activity towards cortisol (F)/cortisone (E) and dexamethasone (D)/11-dehydro-dexamethasone (DH-D) in microsomes prepared from human kidney cortex. For the reaction E to F (not for DH-D to D!), glucose-6-phosphate and glucose-6-phosphate-dehydrogenase had to be added as a NADH/NADPH-regenerating system. Oxidation of F to E: NAD was the exclusively used cosubstrate; the affinity [Michael's constant (Km) for F = 25.5 nmol/L] and the maximum velocity (Vmax = 22.9 nmol/mg/min) were high. Reduction of E to F: Without the NADH/NADPH-regenerating system, this reaction was very slow. With this system, the Km value for E was in the nanomolar range (80.6 nmol/L) and the Vmax value was very low (0.88 nmol/mg/min). The reaction was clearly NADH-preferring. For the steroid pair F/E, the quotient Vmax(oxidation)/Vmax(reduction) (=26) demonstrates an equilibrium far on the 11-keto side. Oxidation of D to DH-D: With NAD as the only used cosubstrate, the kinetic analysis is compatible with the existence of two different NAD-dependent isoenzymes: Km for D = 327 nmol/L, Vmax = 53.5 nmol/mg/min and Km for D = 81.2 nmol/L; Vmax = 20.4 nmol/mg/min. Reduction of DH-D to D: The maximum velocity was higher than that of all other reactions tested: Vmax = 226.0 nmol/mg/min. The reaction was exclusively NADH-dependent; the Km value for DH-D was 68.4 nmol/L. For D/DH-D, the ratio Vmax(oxidation)/Vmax(reduction) was 0.24, demonstrating a shift to reductase activity with the reaction equilibrium far on the 11-hydroxy side. The reaction F to E was inhibited by E, DH-D, and D in a concentration-dependent manner. In conclusion, the cosubstrate dependence, the Km value of the oxidation of F and the product inhibition are in good correspondence with data for the cloned human 11beta-HSD-II. The NADH-dependent 11beta-reduction of E and especially of DH-D are inconsistent with the dogma of an unidirectional 11beta-HSD-II. The preference of D for the reductase reaction in human kidney slices is probably caused by the fluor atom in position 9, is catalyzed by 11beta-HSD-II, and leads to an activation of 11-DH-D to D in the human kidney.

Effects of incremental infusions of arginine vasopressin on adrenocorticotropin and cortisol secretion in man.

Arginine vasopressin (AVP) regulates ACTH release under certain conditions, and exogenously administered AVP is used clinically to stimulate ACTH secretion. We attempted to determine at what plasma concentration AVP can stimulate ACTH release. Six normal men were given infusions of AVP (Ferring) or vehicle between 1600 and 1700 h on five occasions: 1) saline (30 mL/h); 2) 10 ng AVP/min; 3) 30 ng AVP/min; 4) 100 ng AVP/min; and 5) 300 ng AVP/min. Plasma AVP, ACTH, and cortisol concentrations were measured every 10 min during the infusions. Basal plasma AVP levels were less than 1 ng/L (less than 0.92 pmol/L). The lowest AVP dose raised plasma AVP into the range found in fluid-deprived subjects (7-8 ng/L;6.5-7.3 pmol/L), but had no effect on plasma ACTH concentrations. AVP in a dose of 30 ng/min also had no effect. The 100 ng AVP/min dose raised plasma AVP concentrations to 51.4-65.5 ng/L (46-60 pmol/L). This increase led to a transient insignificant increase in plasma ACTH from 13.9 +/- 1.2 (+/- SEM) ng/L (3.1 +/- 0.3 pmol/L) to 20.0 +/- 1.4 ng/L (4.4 +/- 0.3 pmol/L), while plasma cortisol rose significantly from 146 +/- 10 to 209 +/- 19 nmol/L (P less than 0.01) after 60 min of infusion. The 300 ng AVP/min dose raised plasma AVP levels to about 260 ng/L (239 pmol/L); the maximal plasma ACTH and cortisol levels were 39.5 +/- 5.0 ng/L (8.7 +/- 1.1 pmol/L; P less than 0.01) and 348 nmol/L (P less than 0.01), respectively. Thus, peripheral plasma AVP levels have to be raised high above the physiological range before ACTH release is stimulated. We conclude that any AVP reaching the adenohypophysis through the peripheral circulation is of much less importance for the regulation of ACTH secretion than is AVP derived from the pituitary portal circulation.

Comparison of low and high dose corticotropin stimulation tests in patients with pituitary disease.

Tetracosactin [corticotropin-(1-24)] is used for clinical testing of adrenocortical responsiveness. The usual dose [high dose test (HDT)] is 250 micrograms. With this test, patients with mild secondary adrenal insufficiency are usually not identified, thus putting them at risk of an adrenal crisis in stressful situations. It was recently reported that a tetracosactin test with approximately 1 micrograms [low dose test (LDT)] identifies patients with mild forms of pituitary-adrenal insufficiency. We performed both the HDT and the LDT in 35 control subjects and in 44 patients with pituitary disease, mostly pituitary tumors. In these patients, more sensitive reference tests for evaluating the pituitary-adrenal axis (insulin-induced hypoglycemia, metyrapone, and CRH tests) were also performed. In the HDT, plasma cortisol was measured 30 and 60 min after tetracosactin injection; in the LDT (0.5 microgram/m2 body surface area), plasma cortisol was measured 20, 30, 40, 50, and 60 min postinjection. In 6 control subjects, tetracosactin plasma levels were also measured after injection. In the HDT, the correlation between 30 and 60 min cortisol levels was extremely high (r = 0.991; P < 0.0001), but the correlation of the LDT with the HDT at 30 min was also highly significant (r = 0.948; P < 0.0001). The lower normal limit of cortisol responses (means of controls minus 2 SD) at 30 min was lower in the LDT by 3.1 micrograms/dL (85 nmol/L) than in the HDT. Compared with the reference tests, the diagnostic sensitivities of the HDT and the LDT were almost identical. Both tests identified patients with moderately to severely pathological insulin and metyrapone tests, but not those with slightly pathological reference tests. In the HDT, plasma tetracosactin rose to more than 60,000 pg/mL shortly after injection. In the LDT, it rose to 1,900 pg/mL. Both concentrations stimulate cortisol (supra-) maximally. Together, these data show that in pituitary disorders the results of the LDT and the HDT are almost identical. Plasma tetracosactin levels in the LDT still rise to levels that maximally stimulate the adrenal. Tetracosactin testing with low or high doses cannot generally replace the more expensive and cumbersome insulin or metyrapone tests.

Dihydrospirorenone, a new progestogen with antimineralocorticoid activity: effects on ovulation, electrolyte excretion, and the renin-aldosterone system in normal women.

Dihydrospirorenone (DHSP; 6 beta,7 beta,15 beta,16 beta-dimethylen-3-oxo-17- alpha-pregn-4-en-21,17-carbolacton) is an aldosterone antagonist 8 times as potent as spironolactone in the rat. It is also a progestogen that suppresses ovulation in normal women at a daily dosage of 2 mg. The effects of this dosage on the renin-aldosterone system and sodium and potassium balances were investigated in two experiments. In study I, 12 healthy women received a diet with 100 mmol sodium and 60-70 mmol potassium per day from days 3-13 of their normal menstrual cycles. Six women took 2 mg DHSP; 6 others received placebo from days 8-13 of the cycle. Sodium excretion in the DHSP group rose from a mean of 79 to 98.5 +/- 8.3 mmol/day during medication. Placebo had no effect. The difference between average sodium excretion rates in subjects treated with DHSP or placebo was close to significance (P = 0.053). Potassium excretion did not change. Weight loss was slightly greater after DHSP than placebo treatment. PRA and plasma and urinary aldosterone rose significantly during DHSP medication. In study II, 12 women on a free diet were studied during a control and a treatment cyle. From days 5-25 of the second cycle, they took 2 mg DHSP (n = 6) or 1 mg cyproterone acetate. Both compounds suppressed ovulation and the rise in progesterone. During cycle 1, sodium excretion, PRA, and aldosterone were higher in the luteal than in the follicular phase, probably due to an antialdosterone effect of progesterone. DHSP reversed this pattern of natriuresis by inducing a significant early natriuresis and a rise in PRA and aldosterone. Cyproterone acetate only abolished differences in natriuresis between the follicular and luteal phases and the rise of PRA and plasma aldosterone in the luteal phase. We conclude that DHSP may be a suitable partner of ethinyl estradiol as a constituent of an oral contraceptive, since its progestogenic and antialdosterone profile is similar to that of progesterone. Other synthetic progestogens are devoid of an antialdosterone effect. The antialdosterone effect of DHSP may help prevent sodium retention and a rise in blood pressure in susceptible women.

The human kidney is a progesterone-metabolizing and androgen-producing organ.

Progesterone (P) is a potent antagonist of the human mineralocorticoid receptor (MR) in vitro. We have previously demonstrated effective downstream metabolism of P in the kidney. This mechanism potentially protects the MR from P action. Here, we have investigated the expression and functional activity of steroidogenic enzymes in human kidney. RT-PCR analysis demonstrated the expression of 5 alpha-reductase type 1, 5 beta-reductase, aldo-keto-reductase (AKR) 1C1, AKR1C2, AKR1C3, 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) type 2, and 17 alpha-hydroxylase/17,20-lyase (P450c17). The presence of 3 beta-HSD type 2 and P450c17 indicated that conversion of pregnenolone to dehydroepiandrosterone (DHEA) and to androstenedione may take place effectively in kidney. To investigate this further, we incubated kidney subcellular fractions with radiolabeled pregnenolone. This resulted in efficient formation of DHEA from pregnenolone, indicating both 17 alpha-hydroxylase and 17,20-lyase activities exerted by P450c17. Radiolabeled DHEA was converted via androstenedione, androstenediol, and testosterone, indicating both 3 beta-HSD type 2 activity and 17 beta-HSD activity. In addition, the conversion of testosterone to 5 alpha-dihydrotestosterone was detectable, indicating 5 alpha-reductase activity. In conclusion, we verified the expression and functional activity of several enzymes involved in downstream metabolism of P and androgen synthesis in human kidney. These findings may be critical to the understanding of water balance during the menstrual cycle and pregnancy and of sex differences in hypertension.

Progesterone metabolism in the human kidney and inhibition of 11beta-hydroxysteroid dehydrogenase type 2 by progesterone and its metabolites.

Progesterone binds with high affinity to the mineralocorticoid (MC) receptor, but confers only very low agonistic MC activity. Therefore, progesterone is a potent MC antagonist in vitro. Although progesterone reaches up to 100 times higher plasma levels in late pregnancy than aldosterone, the in vivo MC antagonistic effect of progesterone seems to be relatively weak. One explanation for this phenomenon could be local metabolism of progesterone in the human kidney, similar to the inactivation of cortisol to cortisone by the 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 2. We studied the metabolism of progesterone in the human kidney in vitro and found reduction to 20alpha-dihydro (DH)-progesterone as the main metabolite. Ring-A reduction to 5alpha-DH-progesterone, 20alpha-DH-5alpha-DH-progesterone, and 3beta,5alpha-tetrahydro (TH)-progesterone was also documented. We further showed for the first time that 17-hydroxylation of progesterone (17alpha-OH-progesterone, 17alpha-OH, 20alpha-DH-progesterone), normally localized in the adrenals and the gonads, occurs in the human adult kidney. We found no formation of deoxycorticosterone from progesterone in the human adult kidney. Using human kidney cortex microsomes, we tested the inhibitory potency of progesterone and its metabolites on the 11beta-HSD type 2. The most potent inhibitor was progesterone itself (IC50 = 4.8 x 10(-8) mol/L), followed by 5alpha-DH-progesterone (IC50 = 2.4 x 10(-7) mol/L), 20alpha-DH-progesterone, 3beta,5alpha-TH-progesterone, 17alpha-OH-progesterone, and 20alpha-DH-5alpha-DH-progesterone (IC50 between 7.7 x 10(-7) mol/L and 1.3 x 10(-6) mol/L). The least potent inhibitor was 17alpha-OH,20alpha-DH-progesterone. In addition to progesterone metabolism by the kidney, the inhibition of 11beta-HSD type 2 by progesterone and its metabolites could be a second explanation for the weak MC-antagonist activity of progesterone in vivo. Inhibition of 11beta-HSD type 2 leads to an increase of intracellular cortisol in a way that the local equilibrium between the MC agonist cortisol and the antagonist progesterone is shifted to the agonist side.

Expression of lipophosphoglycan, high-molecular weight phosphoglycan and glycoprotein 63 in promastigotes and amastigotes of Leishmania mexicana.

The abundant surface glycoconjugate of Leishmania promastigotes, lipophosphoglycan (LPG), forms a blue-colored complex (lambda max = 649 nm) with the cationic dye Stains-all, which can be quantitated densitometrically on polyacrylamide gels of cell lysates. Promastigotes of Leishmania mexicana, Leishmania major and Leishmania donovani yield values of 1-3 x 10(6) LPG molecules cell-1. In amastigotes the LPG content is down-regulated below the detection limit (< 10(3) molecules cell-1) in L. mexicana and L. donovani, but remains significant in L. major (2 x 10(3) molecules cell-1). In the case of L. mexicana, these results are supported by immunological studies. Using several monoclonal and polyclonal antibodies, LPG is undetectable by immunoblotting in lysates of either amastigotes or infected macrophages and the amastigote surface is devoid of LPG as judged by immunofluorescence and immunoelectron microscopy. Immunoblotting experiments demonstrate that amastigotes synthesize hydrophilic high-molecular weight compounds which stain blue with Stains-all and cross-react with the monoclonal and polyvalent antibodies suggesting the presence of similar phosphoglycan structures as in LPG. The high-molecular weight phosphoglycan appears to be located in the lumen of the flagellar pocket of mouse lesion amastigotes and may be secreted from there into the lumen of the parasitophorous vacuole of parasitized macrophages. In L. mexicana promastigotes the surface protease gp63 is amphiphilic and comprises about 1% of the cellular proteins. In contrast, in amastigotes gp63-related proteins are predominantly hydrophilic; they amount to only about 0.1% of the cellular proteins and are mainly located in the lumen of the extended lysosomes (megasomes) characteristic for this species.

Evidence for isoforms of 11 beta-hydroxysteroid dehydrogenase in the liver and kidney of the guinea pig.

In the human and in rodents like the rat and mouse, the liver enzyme 11 beta-hydroxysteroid dehydrogenase type I (11 beta-HSD-I) is a functional oxidoreductase preferring NADP+/NADPH as cosubstrate, while the renal isoenzyme (11 beta-HSD-II) prefers NAD+ as cosubstrate, and seems to be a pure oxidase and protects the tubular, mineralocorticoid (MC) receptor from occupancy by cortisol and corticosterone. We studied the enzyme kinetics of 11 beta-HSDs in kidney and liver microsomes of the guinea pig, a species whose zoological classification is still a matter of debate. With a fixed concentration of 10(-6) mol/l cortisol, liver and kidney microsomes preferred NAD+ to NADP+ (10(-3) mol/l) for the conversion to cortisone. Kidney microsomes converted cortisol to cortisone with K(m) values of 0.64 mumol/l and 9.8 mumol/l with NAD+ and NADP+ as cosubstrates respectively. The reduction of cortisone to cortisol was slow with kidney microsomes, but could be markedly enhanced by adding an NADH/NADPH regenerating system: with NADPH as preferred cosubstrate, the approximate K(m) was 7.2 mumol/l. This indicated the existence of both isoenzymes in the guinea pig kidney. Liver microsomes oxidized cortisol to cortisone with similar K(m) and Vmax values for NAD+ to NADP+ as cosubstrates (K(m) of 4.3 mumol/l and 5.0 mumol/l respectively). The NAD+ preference for the oxidation of 10(-6) mol/l cortisol described above may be due to a second, NAD(+)-preferring 11 beta-HSD with a K(m) of 1.4 mumol/l. In contrast to the kidney, liver microsomes actively converted cortisone to cortisol with a preference for NADPH (K(m): 1.2 mumol/l; Vmax: 467 nmol/min per mg protein). Thus, the main liver enzyme is similar to the oxidoreductase of other species (11 beta-HSD-I) and is also present in the kidney, while the main kidney enzyme is clearly NAD(+)-preferring. This kidney enzyme (analogous to 11 beta-HSD-II of other species) seems to be suitable for the protection of the MC receptor from the high free plasma cortisol levels of the guinea pig.

Expression of the progesterone receptor and progesterone- metabolising enzymes in the female and male human kidney.

Due to high binding affinity of progesterone to the human mineralocorticoid receptor (hMR), progesterone competes with the natural ligand aldosterone. In order to analyse how homeostasis can be maintained by mineralocorticoid function of aldosterone at the MR, especially in the presence of elevated progesterone concentrations during the luteal phase and pregnancy, we investigated protective mechanisms such as the decrease of free progesterone by additional binding sites and progesterone metabolism in renal cells. As a prerequisite for sequestration of progesterone by binding to the human progesterone receptor (hPR) we demonstrated the existence of hPR expression in female and male kidney cortex and medulla at the level of transcription and translation. We identified hPR RNA by sequencing the RT-PCR product and characterised the receptor by ligand binding and scatchard plot analysis. The localisation of renal hPR was shown predominantly in individual epithelial cells of distal tubules by immunohistology, and the isoform hPR-B was detected by Western blot analysis. As a precondition for renal progesterone metabolism, we investigated the expression of steroid-metabolising enzymes for conversion of progesterone to metabolites with lower affinity to the hMR. We identified the enzyme 17alpha-hydroxylase for renal 17alpha-hydroxylation of progesterone. For 20alpha-reduction, different hydroxysteroid dehydrogenases (HSDs) such as 20alpha-HSD, 17beta-HSD type 5 (3alpha-HSD type 2) and 3alpha-HSD type 3 were found. Further, we detected the expression of 3beta-HSD type 2 for 3beta-reduction, 5alpha-reductase (Red) type 1 for 5alpha-reduction, and 5beta-Red for 5beta-reduction of progesterone in the human kidney. Therefore metabolism of progesterone and/or binding to hPR could reduce competition with aldosterone at the MR and enable the mineralocorticoid function.