Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

The definition of a spontaneous growth hormone (GH) peak: studies in normally growing and GH-deficient children

GH spontaneous peaks and their diagnostic utility have not been previously evaluated by means of a 24-h continuous withdrawal (CW) procedure in children with growth disorders. Using a CW pump, we studied the 24-h spontaneous secretion of GH in 129 prepubertal subjects grouped as follows. The control group (C) consisted of 20 children of normal height and growth rate. Group GHD consisted of 53 patients with classical GH deficiency (48 idiopathic and 5 organic). The NSD group consisted of 36 patients with a growth velocity below 4.5 cm/yr, normal GH response to provocative stimuli (PS), but a mean 24-h GH in the deficient range. Group NSS consisted of 20 short children with normal growth velocity, normal PS, and normal mean 24-h GH concentration. The mean GH levels for the 24-h period were 4.1 +/- 1.7, 1.4 +/- 0.5, 2.1 +/- 0.7, and 4.2 +/- 1.9, respectively, for the C, GHD, NSD, and NSS groups. For each subject, GH levels were determined in 48 0.5-h samples collected during the CW study, and the GH profile was analyzed by the Pulsar computer program. The mean number of peaks was 9.0 +/- 2.5 for C, 9.5 +/- 3.7 for GHD, 10.5 +/- 1.8 for NSD, and 9.5 +/- 3.2 for NSS. There was no statistical difference between groups. The mean amplitude of peaks was 9.8 +/- 8.9 for C, 1.6 +/- 1.0 for GHD, 2.9 +/- 1.3 for NSD, and 9.9 +/- 9.1 for NSS. Mean peak amplitudes in both GHD and NSD were significantly lower than in the C and NSS groups. The presence of peaks of more than 8 micrograms/L during the daytime (0800-2000 h) was a characteristic of children with normal integrated GH concentration (IC-GH) and was seen in 90% of normally growing children but in only 7% of poorly growing children with subnormal IC-GH. There was no significant difference in the number of pulses during the night between C and NSD groups. We conclude that differences in IC-GH between normally growing and poorly growing children are due to a lower amplitude of peaks during the daytime hours.

The diagnostic value of integrated growth hormone secretion studies shorter than 24 hours in normal- and short-growing children

Spontaneous growth hormone (GH) secretion is evaluated by measurement of the 24-hour integrated concentration of GH (24-hour IC-GH), a major diagnostic procedure, or by shorter protocols such as monitoring 6 h during sleep. We have evaluated several possibilities for shortening the procedure by comparing the results of an abbreviated procedure to the 24-hour IC-GH studies. The study population consisted of 50 children with classic GH deficiency (group GHD), determined by provocative testing, and 45 children who had a subnormal secretion of GH (group N), determined by low 24-hour IC-GH but normal GH provocative tests. Twenty-two children of normal height and stature served as a control group. All the children were prepubertal, while there was no overlap between the lower 5th percentile of the 24-hour IC-GH of the control subjects (3.3 micrograms/l) and the upper 97th percentile of the 24-hour IC-GHs of the N and GHD groups (2.9 and 2.7 micrograms/l, respectively), there was a considerable overlap between the IC-GH of control subjects and that of the GHD and N groups measured in all the abbreviated blood withdrawal protocols, except for the 10-hour daytime and the 12-hour nighttime protocols of the GHD patients. It should be noted that there was only a small overlap between the control and the GHD groups during the 12-hour daytime protocol. We have found that the longer the blood collection period the greater the sensitivity and the specificity. We conclude that the 24-hour IC-GH test is the best diagnostic tool for identifying children with subnormal GH secretion.

Assessment of growth hormone secretion in normal stature children using 24-hour integrated concentration of GH and pharmacological stimulation

The integrated concentration of serum GH (IC-GH) is used for the assessment of spontaneous GH secretion. In order to use the IC-GH as a diagnostic tool a normative reference range needs to be established. We determined the IC-GH by continuous blood withdrawal in 119 children of normal height, weight and growth rate. Although the mean IC-GH increased with pubertal status, 4.4 +/- 1.2 micrograms/L at Tanner I (n = 36), 5.5 +/- 2.1 micrograms/L at Tanner II-III (n = 43), and 5.8 +/- 1.6 at Tanner IV-V (n = 40) (P less than 0.03), there was a considerable overlap of individual IC-GH levels between the pubertal groups. Gender affected the mean IC-GH level slightly, but not the range. Although the mean IC-GH of girls tended to be higher than that of boys this difference was not statistically significant. Ninety five percent of the IC-GH values were above the 3.2 micrograms/L level. The response to pharmacological stimulation (clonidine, insulin, or arginine) was also evaluated in 68 of the subjects. The peak GH response to pharmacological stimulation (micrograms/L) with clonidine 21.0 +/- 10.7 (n = 66) was significantly higher than to either arginine 13.1 +/- 6.1 (n = 23) or insulin 14.2 +/- 6.3 (n = 19) (P less than 0.01). The peak response to clonidine increased significantly with pubertal status (P less than 0.001) and there was an interactive effect of gender and pubertal stage where the GH response of prepubertal boys exceeded that of prepubertal girls but the response of pubertal girls exceeded that of pubertal boys (P less than 0.02). The peak stimulated GH levels was correlated with IC-GH in this subgroup r = 0.52, P less than 0.0001). This study provides a large normative data base for IC-GH and the GH provocative tests in normally growing children of varying pubertal status.

Somatotropin as measured by a two-site time-resolved immunofluorometric assay

To date, many of the current criteria for diagnosis of somatotropin (growth hormone, GH) deficiency have been based upon measurement of this hormone by competitive radioimmunoassay (RIA) with use of polyclonal antibodies. In recent years, however, the development of hybridoma technology has led to the generation of various monoclonal antibodies (Mabs) to GH with different affinities and epitope specificities. Subsequently, these reagents have been used in the development of noncompetitive two-site immunometric assays (e.g., immunoradiometric assay; IRMA). In general, the values obtained for serum GH by IRMA have been lower than those obtained by RIA, because of the epitope-specificity profile of the Mabs in the IRMA. Attempting to obtain GH values numerically similar to those by RIA, we used a combination of Mabs to GH in developing and evaluating a two-site time-resolved immunofluorometric assay (IFMA) based on the streptavidin-biotin interaction. Fluorescence is proportional to concentration of analyte and is linearly related to concentration over the range 0.3 to 40 micrograms/L. The assay was satisfactory with respect to sensitivity, accuracy, and precision (CV less than 10% over the entire working range). In addition, the concentration of GH was determined by the IFMA and a competitive RIA in serum obtained from GH deficient and acromegalic patients. The pairing of antibodies in the IFMA gave numerical values that agreed well with those by RIA (r = 0.97; n = 100).

Somatotropin as measured by a two-site time-resolved immunofluorometric assay

To date, many of the current criteria for diagnosis of somatotropin (growth hormone, GH) deficiency have been based upon measurement of this hormone by competitive radioimmunoassay (RIA) with use of polyclonal antibodies. In recent years, however, the development of hybridoma technology has led to the generation of various monoclonal antibodies (Mabs) to GH with different affinities and epitope specificities. Subsequently, these reagents have been used in the development of noncompetitive two-site immunometric assays (e.g., immunoradiometric assay; IRMA). In general, the values obtained for serum GH by IRMA have been lower than those obtained by RIA, because of the epitope-specificity profile of the Mabs in the IRMA. Attempting to obtain GH values numerically similar to those by RIA, we used a combination of Mabs to GH in developing and evaluating a two-site time-resolved immunofluorometric assay (IFMA) based on the streptavidin-biotin interaction. Fluorescence is proportional to concentration of analyte and is linearly related to concentration over the range 0.3 to 40 micrograms/L. The assay was satisfactory with respect to sensitivity, accuracy, and precision (CV less than 10% over the entire working range). In addition, the concentration of GH was determined by the IFMA and a competitive RIA in serum obtained from GH deficient and acromegalic patients. The pairing of antibodies in the IFMA gave numerical values that agreed well with those by RIA (r = 0.97; n = 100).

Incidence of neurosecretory dysfunction among children aged 6-14 years in Rehovot, Israel

Screening of 7500 children aged between 5.8 and 14.4 years, out of a total population of 39,690 in this age group in the Rehovot region, revealed 111 children with heights 2.5 SD below the mean for their age, according to the Tanner-Whitehouse standards. Included among these short children were eight with hypochondroplastic skeletal disease, two with Down's syndrome, four with thalassaemia, four with Turner's syndrome, three with coeliac disease, four with classical growth hormone (GH) deficiency, four with intrauterine growth retardation, four with systemic disease and 78 without obvious underlying causes. In 35 of the 78 children in the last group, the 24-hour integrated concentration of GH was in the hypopituitary range (less than 3.2 ng/ml), and GH neurosecretory dysfunction (NSD) was accordingly diagnosed. This represents an incidence of GH neurosecretory dysfunction of 45% among abnormally short children without underlying pathology, and is consistent with the authors' previous findings. The overall frequency of GH neurosecretory dysfunction in the screened population was 4/1000.

The diagnostic value of the 24 hour integrated concentration of plasma aldosterone

The 24-hour urinary excretion rate of aldosterone, the 24-hour integrated concentration of plasma aldosterone (IC-ALDO) and the morning plasma aldosterone levels from a single, discrete venipuncture of 92 subjects (30 normal subjects, 62 patients with mild, essential hypertension) were compared, using the variance ratio method, to 12 patients with primary aldosteronism. The variance of the IC-ALDO was significantly lower than the respective variances of the 24-hour urinary excretion of aldosterone (P less than 0.01) and of the discrete, morning plasma levels of aldosterone (P less than 0.01). The clinical usefulness of this diagnostic procedure depends on its ability to discriminate between healthy subjects and various hypertensive patients. Because of its narrower variance and enhanced discriminatory ability, the 24-hour IC-ALDO may have useful application in diagnosis of various disorders of aldosterone secretion. We have found the IC-ALDO completely separated 11 of 12 primary aldosteronism patients (mean 36 +/- 17) from essential hypertensive controls (mean 9.6 +/- 4.1) (P less than 0.01). When IC-ALDO was combined with integrated concentration of plasma renin activity in an ALDO/RENIN ratio, all 12 primary aldosteronism patients were diagnosed.

The dawn phenomenon, an early morning glucose rise: implications for diabetic intraday blood glucose variation

Eleven insulin-dependent (type I) diabetic subjects were studied during a 24-h period to assess intraday blood glucose (BG) variation and related free insulin (FI) levels. Ten patients exhibited the dawn phenomenon, a rise in early morning fasting blood glucose (123 +/- 81.1 m/dl; mean +/- SD). This increase was positively and significantly correlated with the morning postprandial BG peak (r = 0.723; P = 0.012). FI/BG ratios were highest during the night (0.717 and 0.666 at 2200 and 0400 h, respectively) and lowest during the early morning (0.294 at 0800 h) (P less than 0.01). Three of the four observed hypoglycemic episodes occurred during the period when free insulin levels were high relative to BG. We conclude that the dawn phenomenon contributed directly and significantly to the BG maximum and indirectly, in some cases, to nocturnal hypoglycemia. It thus played an important role in the intraday blood glucose variation of such patients.

Preferential binding of testosterone over epitestosterone by human plasma

The main purpose of this study was to investigate if the specificity of the binding of testosterone to plasma proteins could be defined as a preferential binding of this steroid over epitestosterone. The amount of testosterone that is specifically bound was calculated using the formula: (see article) concentration, where "Ri" is the ratio (14C) testosterone: (3H) epitestosterone in plasma prior to centrifugation, "Ru" is the isotope ratio in the protein-free supernatant obtained after ultracentrifugation (149,000 x g, at 0 C, for 18 h) and "T concentration" is the testosterone concentration in plasma resulting from addition of (14C) testosterone, the endogenous steroids having been removed by preliminary charcoal extraction. The theoretical separation of the binding sites for testosterone into two populations, one non-specific with no preference for testosterone over epitestosterone, and another with absolute specificity for testosterone over its physiologically inactive stereoisomer, proved to be useful. Ovalbumin was found to be an example for non-specific, non-preferential binding. Determination of the ratio (14C) testosterone: (3H) epitestosterone in the successive fractions of various ultracentrifuged preparations showed a small but significant preference for (14C) testosterone by human and bovine serum albumin, while alpha1-acid glycoprotein had a preference for (3H) epitestosterone. Saturation curves showed at least two components: the first one, presumably corresponding to TeBG, had a higher affinity and lower capacity. This binding capacity can be accurately determined by extrapolation to the ordinate or the second component, a straight line corresponding to a binding of somewhat lower affinity and much larger capacity.

Blood glucose monitoring in symptomatic hypoglycemia

The relationship between blood glucose levels and the onset of hypoglycemic symptoms was studied by continuous monitoring of blood glucose levels after an oral glucose load in nine adults with normal glucose tolerance, five with chemical diabetes without symptomatic hypoglycemia, and nine with chemical diabetes with symptomatic hypoglycemia. Symptoms were associated not only with a low level of blood glucose but with a rapid fall as well. These two parameters were used to calculate a "hypoglycemic index" (defined as the fall in blood glucose during a 90-minute period prior to reaching the minimum level, divided by the value of this minimum level). The hypoglycemic index was 2.3 +/- 0.6 (mean +/- S.D.) in the group of diabetic patients with symptomatic reactive hypoglycemia and 0.7 +/- 0.3 for the other groups. This index may aid in the diagnosis of patients with symptoms of hypoglycemia and equivocally low values of blood glucose.

Sterospecific tissue uptake and nuclear accumulation of testosterone in the development of the mouse erythropoietic spleen

A double isotope ratio technique was used to estimate the specific binding of testosterone (T), as opposed to its biologically nonactive stereoisomer, epitestosterone (Epi T). The mouse erythropoietic spleen formed in response to a phenylhydrazine-induced hemolytic anemia was used as the target organ. Spleen minces from preanemic mice, as well as those in the early and late phases of erythropoietic spleen development, were incubated with 10(-9) M of 14C-T and 3H-EpiT, and the selective uptake of T was calculated from the 14C/3H ratio measured in the media before and after incubation, as well as in the subcellular fractions of the minces. Preferential uptake of T was seen in the early phase of development, but not in spleens obtained from preanemic animals or those in the late phase. There was no evidence of metabolic conversion of T or EpiT. The selective uptake of T by early phase spleens was reflected in a preferential nuclear accumulation of T. These data represent the first demonstration of a specific binding of T in vitro to a developing erythroid tissue.

Measurement of sulfamethizole clearance rate by nonthrombogenic constant blood-withdrawal system

A method for the measurement of the total body clearance rate (CR) of drugs is described. It involves a single intravenous injection of a known quantity of the drug (D) and automatic integration of the plasma concentration curve, using a portable, nonthrombogenic, constant blood-withdrawal system. When blood withdrawal is carried out until the concentration of the drug in the plasma approaches zero, the concentration of the drug in the collected pool, the integrated concentration (ICT) multiplied by the time of collection (T) yields the integral of the concentration curve: (see article). The method was tested by measuring the clearance rate of sulfamethizole in five dogs by the established constant infusion method. At three plasma levels (25, 75, and 200 mg/liter), the plasma concentration had no significant effect on the clearance rate. The clearance rate of sulfamethizole was subsequently measured in the same dogs by the new single-injection constant withdrawal method. Multiple blood samples were collected at 15-min intervals simultaneously with the constant withdrawal of blood. There was no significant difference between the clearance rate of sulfamethizole measured by the two methods. The initial peak mean concentration of the drug from the time of injection (t = 0) to the time of the first blood sampling (t = 15 min) was calculated from the difference between (see article) obtained by the constant withdrawal method and that obtained from the results of the multiple blood withdrawals by the trapezoidal rule. The integrated concentration IC15 was significantly higher than its estimation by the semilogarithmic linear regression method.

Long-term effects of vasectomy on pituitary-gonadal function in man

Plasma concentrations of testosterone (T), follicle stimulating hormone (FSH), and luteinizing hormone (LH) and percent binding of T to plasma protein (TB) were studied in 16 normal fertile men and in 81 men who had undergone vasectomy from 1 to 5 yr earlier. No significant difference from the control values to T = 582 plus or minus 39.5 (SE) ng/100 ml; FSH = 15.09 plus or minus 2.18 (SE) mIU/ml; LH =10.03 plus or minus 1.13 (SE) mIU/ml and TB = 92.99 plus or minus 0.285 (SE) % binding was detected in any group of the vasectomized men in any of the parameters studied.

Lack of correlation between gonadotropin and adrenal androgen levels in agonadal children

To evaluate the relationship between the secretion of gonadotropins and adrenal androgens, patients with gonadal agenesis were evaluated by (a) administering human luteinizing hormone (hLH) for 5 days with or without estrogen pretreatment to agonadal patients who had prepubertal LH levels; (b) correlating circulating gonadotropin levels with adrenal androgens in 45 patients; and (c) comparing adrenal androgens with gonadotropins after long-term administration of estrogen or androgens. Results are as follows: (a) No alteration in serum concentrations of dehydroepiandrosterone (DHA), dehydroepiandrosterone sulfate (DHAS), estrone (E1), testosterone (T), or in excretion of urinary 17-ketosteroid (17 KS) occurred after the administration of hLH. (b) No clearcut relationship between endogenous level of LH or FSH and DHA OR DHAS was demonstrated although a coincident increase of all hormones with age occurred. (c) Administration of estrogen to patients with gonadal agenesis did not affect their levels of DHA and DHAS although those patients given androgen developed higher DHAS, but not DHA, levels. Hence, increasing gonadotropin concentrations would not appear to be a primary etiologic factor in the maturation of the adrenal.

Adrenal function in normal infants and in marasmus and kwashiorkor. Cortisol secretion, diurnal variation of plasma cortisol, and urinary excretion of 17-hydroxycorticoids, free corticoids, and cortisol

Normal infants exhibited circadian rhythmicity of plasma F concentration. Infants from 2.1 to 3.2 months of age had CSR significantly higher than those of older infants. THF/THE urinary excretion ratios increased with age. The 17OHCS excretion was higher in the younger infants. Urinary excretions of free corticoids and cortisol were similar in all age groups. In marasmus, plasma F concentrations in the morning and evening were significantly elevated. Normal diurnal variation returned following therapy. CSR and 17OHCS excretions were not different from age controls, but were significantly lower than size controls, THF/THE ratios, urinary excretion of free corticoids and cortisol were normal. In marasmic kwashiorkor, plasma F concentrations were significantly elevated in the morning and evening. There was a suggestive decrease with therapy. CSR was low before and after treatment. THF/THE ratios, urinary 17OHCS excretion, and urinary free corticoids and cortisol were not significantly different from infants matched for size or patients with marasmus.

Circadian variation of integrated concentration of growth hormone in children and adults

A portable constant withdrawal pump was used to determine consecutive 30-min integrated concentrations of growth hormone (ICGH) for a 24-h period in 18 normal subjects, ages 5 to 28 yr. Seven prepubertal, 5 pubertal and 6 young adult subjects were studied under conditions of normal activity. Pubertal, prepubertal, and adult subjects had peaks during waking hours as well as during sleep, but peaks in the adults were usually lower than in the children. Using an analysis of variance, a significant (P smaller than 0.01) downward trend of ICGH was observed to occur during sleep. During waking hours a significant variation (P smaller than 0.01 by analysis of variance) was found with low levels in the first few hours after awakening and an upward trend as the evening approached. Food intake had no significant effect on ICGH nor did the introduction of the indwelling catheter. The mean apparent half-life values of growth hormone calculated on the basis of 87 episodes with 3 or more points on the downslope was 40.1 min. This is significantly higher than the known true half-life of the hormone, suggesting that complete secretory inactivity after a secretory episode is an infrequent event.

Integrated concentration of plasma aldosterone in normal subjects: correlation with cortisol

The integrated concentration (I. C.) of plasma aldosterone and cortisol was determined every 30 min during a 24-h period, using a blood collection system composed of a nonthrombogenic catheter and a small, portable withdrawal pump. The experiments were carried out in 8 normal adult men during daily routine life, and repeated in 2 of the subjects while recumbent in bed most of the day. The following conclusions were made: a) The 30-min I. C. of aldosterone fluctuated widely throughout the day. b) Although peaks of increased concentration occurred after a change in posture from supine to erect, there were many peaks of concentration that occurred during the supine posture. The 24-h I.C. of aldosterone in 2 subjects that were studied a second time while staying in bed most of the day was lower than the I. C. observed during normal activity. Furthermore, there was a significant correlation between 24-h I. C. and percentage of time spent in supine position. c) A weak, but significant correlation was found between the 30-min I. C. of aldosterone and cortisol in 4 out of the 7 subjects tested. The overall correlation for all experiments was also significant (R = 0.3. p smaller than 0.001). D) The 4-h I. C. of aldosterone and cortisol showed that the lowest mean values were between 4 PM and 4 AM and the highest values between 4 AM and 4 PM for both steroids.

Growth hormone: metabolic clearance rates, integrated concentrations, and production rates in normal adults and the effect of prednisone

A constant withdrawal pump was used to determine the integrated concentration of growth hormone (ICGH) which was used in conjunction with the metabolic clearance rate (MCR) of growth hormone (GH) to calculate the GH production rates (GHPR) in normal adults, acromegalics, and normal controls receiving prednisone. The mean ICGH for 22 premenopausal females on no medication was 3.0+/-1.6 ng/ml (sd) which is significantly lower (P < 0.005) than the mean of 6.6+/-2.9 for 10 women receiving oral contraceptives and significantly higher than the means of 1.5+/-0.75 for 5 postmenopausal females (P < 0.05) and 1.8+/-1.0 for 16 adult males (P < 0.01) which are comparable. The mean GHPR's in mg/24 hr per m(2) for the four groups are: normal females = 0.52+/-0.24 (sd), females receiving contraceptive pills = 1.65+/-0.58 (P < 0.005), postmenopausal females = 0.26+/-0.12 (P < 0.025), and adult males 0.35+/-0.23 (P < 0.025).Three untreated acromegalic patients had ICGH's of 59, 82, and 93 ng/ml and GHPR's ranging from 14.5 to 17.9 mg/24 hr. Prednisone in a dose of 20 mg t.i.d. for 8 days significantly decreased both the ICGH and GHPR. Alternate day prednisone (60 mg in a single q.o.d. dose) resulted in less consistent inhibition of GH release which may play a role in the more normal growth seen in children receiving q.o.d. prednisone.

Plasma concentration of testosterone, dihydrotestosterone, testosterone-oestradiol binding globulin, and pituitary gonadotrophins in the syndrome of male pseudo-hermaphroditism with testicular feminization

Twenty patients with the syndrome of testicular feminization have been studied along with a group of normal subjects of both sexes and of comparable ages. Peripheral and gonadal venous blood were analysed for their content in testosterone (T), androstenedione (Δ), dihydrotestosterone (DHT), testosterone-oestradiol binding globulin (TeBG), luteinizing hormone (LH) and follicle stimulating hormone (FSH). Normal or even higher than normal male concentrations of T, Δ, and DHT were observed. An actual secretion of the three androgens by the testis was demonstrated. Elevated levels of serum LH were found despite normal male or higher levels of T, Δ, and DHT. High concentrations of TeBG presumably could alter the dynamics of plasma androgens. The gonadal production of DHT and the normal levels of DHT in peripheral plasma shows that 5α-reductase activity is definitely present in the patients.

Plasma aldosterone concentration at delivery and during the newborn period

Aldosterone concentrations in plasma of women on normal sodium intake undergoing cesarean section were 3.7+/-1.4 ng/100 ml (mean+/-1 SD). These values were significantly lower (P < 0.001) than those observed in mothers on normal sodium diet, delivered by the vaginal route (14.9+/-7.0 ng/100 ml). A significant elevation (P < 0.001) of the concentrations was found if the mothers had been on sodium restriction and/or diuretics (44.9+/-24.2 ng/100 ml). In supine position, adult nonpregnant subjects have aldosterone concentrations in plasma of 1.7+/-1.4 ng/100 ml on normal sodium intake and of 16.7+/-8.1 ng/100 ml on low sodium diet.Simultaneous determinations of aldosterone levels in cord blood showed that cord values were significantly higher than those of the corresponding mother (P < 0.01 by paired t test). However, values in cord blood of infants born to mothers on a normal sodium intake were significantly lower (P < 0.005) than those of infants whose mothers had required low sodium diet and/or diuretics during their pregnancy. Aldosterone concentrations in plasma of infants 1-72 hr of age and born to mothers on normal sodium intake were 25.9+/-11.7 ng/100 ml (mean +/-1 SD). These values were significantly lower (P < 0.005) than those of infants born to mothers on restricted sodium intake with or without diuretics (80.3+/-54.4 ng/100 ml). The concentrations at birth were not significantly different from those observed during the first 3 days of life (P > 0.6).

The regulation of aldosterone secretion in anephric man

The regulation of aldosterone secretion in anephric man was investigated in studies on nephrectomized patients who were being intermittently hemodialyzed while awaiting renal transplantation. The effects of supine and upright posture on the concentration of plasma aldosterone on the 1st day postdialysis and on a 3rd or 4th day postdialysis were compared to the effects of postural variation in normal subjects who were on a low sodium intake and on a high sodium intake. In contrast with the normal subjects who exhibited higher concentrations of plasma aldosterone after 2 hr of upright posture than in the supine position and low concentrations of plasma aldosterone on a high sodium intake, the anephric patients showed less consistent variations in plasma aldosterone due to changes in posture and exhibited higher concentrations of plasma aldosterone on the 3rd or 4th day postdialysis, despite an increase in body weight, than on the 1st day postdialysis. The increase in the concentration of plasma aldosterone in the anephric patients between the 1st day postdialysis and the 3rd or 4th day postdialysis indicates that aldosterone secretion is not responding primarily, in this situation, to volume-related stimuli. There was a high degree of correlation between the concentration of plasma aldosterone and the corresponding levels of serum potassium concentration, which also rose significantly between the 1st day postdialysis and the 3rd or 4th day postdialysis. Furthermore, when potassium accumulation between dialyses was prevented in three of these patients, the concentration of plasma aldosterone fell to minimally detectable levels. The results of these studies suggest that the primary regulator of aldosterone secretion in the absence of the kidneys is potassium.

Transplacental passage and fetal secretion of aldosterone

The transplacental passage and the production of aldosterone were studied in late pregnancy during a constant infusion of 1,2-aldosterone-(3)H to mothers at the time of elective cesarean section. It was found that, while maternal aldosterone crossed the placenta, there was a significant secretion of aldosterone by the fetus. The aldosterone concentration in fetal plasma was 2-12 times higher than that of the corresponding mothers. Pregnancy had no effect on the metabolic clearance rate of aldosterone, but it increased the rate of production of this steroid. However, the increments that we observed were smaller than those reported in previous reports. The discrepancy was probably due to differences in body posture, our subjects being supine for at least 10 hr at the time of study.