Oral octreotide capsules for the treatment of acromegaly: comparison of 2 phase 3 trial results

PURPOSE

Results are presented from 2 to 3 trials investigating oral octreotide capsules (OOC) as an alternative to injectable somatostatin receptor ligands (iSRLs) in the treatment of acromegaly.

METHODS

CH-ACM-01 was an open-label trial (N = 155) and CHIASMA OPTIMAL was a double-blind placebo-controlled (DPC) trial (N = 56), both investigating OOC as maintenance therapy for patients with acromegaly who were biochemical responders receiving iSRLs.

RESULTS

Baseline characteristics in both trials reflected those expected of patients with acromegaly responding to treatment and were similar between trials, despite differences in inclusion criteria. OOC demonstrated a consistent degree of biochemical response across trials, with 65% of patients in CH-ACM-01 maintaining response during the core period and 64% of patients in CHIASMA OPTIMAL at the end of the DPC. Mean insulin-like growth factor I (IGF-I) levels remained within inclusion criteria at the end of treatment in both trials. Of 110 patients entering the fixed-dose phase in CH-ACM-01, 80% maintained or improved acromegaly symptoms from baseline to the end of treatment. Over 85% of patients in both trials elected to continue into the extension phases. OOC were found to be well tolerated across both trials, and no dose-related adverse events were observed.

CONCLUSIONS

OOC demonstrated remarkably consistent results for biochemical response, durability of response, and preference to continue with oral treatment across these 2 complementary landmark phase 3 trials, despite differences in the design of each. Trial registration NCT03252353 (August 2017), NCT01412424 (August 2011).

Comparison of expression levels of candidate genes in endometrium of dairy heifers and lactating dairy cows

Pretheeban, T., Gordon, M. B., Singh, R. and Rajamahendran, R. 2011. Comparison of expression levels of candidate genes in endometrium of dairy heifers and lactating dairy cows. Can. J. Anim. Sci. 91: 255–264. Pregnancy rates (PR) in high-producing lactating dairy cows have declined drastically over the past several decades, but those of heifers have remained constant. Reduced PR could be due to multiple causes, and the underlying pathophysiological mechanisms are still unclear. A compromised maternal uterine environment could be one of factors that could affect the PR. This study was performed to compare the nature of the uterine environment in dairy heifers and lactating dairy cows (2nd/3rd parity) by analyzing the expression levels of selected endometrial genes. Estrus was synchronized in heifers (n=5) and lactating dairy cows (n=5) and endometrial biopsies were performed during the mid luteal phase (day 11) of the estrous cycle. Real-time polymerase chain reaction (Q-RT PCR) and immunohistochemistry were performed to analyse the mRNA and protein levels of genes respectively. Relative abundance of BCL2, HSPA1A, IL1A, TNF, IGF1, FGF2 and SERPINA14 transcripts and the protein expression of IL1A, TNF and FGF2 were significantly higher in heifers in comparison with lactating dairy cows. Our findings suggest an altered endometrial environment in lactating dairy cows compared with heifers. However, whether these differences play a role in pregnancy outcomes should be further investigated.

Effects of presynchronization and postinsemination treatments on pregnancy rates to a timed breeding Ovsynch protocol in dairy cows and heifers

This study examined two strategies to improve pregnancy rate (PR) following Ovsynch timed artificial insemination (TAI) for lactating dairy cows (n = 225) and nulliparous heifers (n = 87). Animals were assigned randomly to receive one of three treatments: Ovsynch protocol (GnRH 7 d before and 48 h after one PGF2α treatment), Presynch + Ovsynch (two treatments of PGF2α 14 d apart followed by Ovsynch 14 d later), or Ovsynch + Post-AI GnRH (GnRH 6 d after Ovsynch TAI) for first service breeding. Pregnancy rates among treatments were not different in lactating cows (42.5, 48.0, and 44.9%) or heifers (65.5, 58.6, and 58.6%) for Ovsynch, Presynch + Ovsynch, and Ovsynch + Post-AI, respectively. Cows treated with Ovsynch had lower PR when bred < 76 d in milk (DIM) compared with Presynch + Ovsynch or Ovsynch + Post-AI treatments. In addition, cows and heifers that received Post-AI GnRH had greater progesterone (P4) concentrations on day 21 and day 28 post-TAI than the Ovsynch group. Animals with higher P4 concentrations at initiation of Ovsynch had better PR than those with low P4 concentrations. Presynch animals had a greater proportion of animals with P4 values above 1 ng mL-1 at the initiation of Ovsynch than those animals in the Ovsynch group (74.5 vs. 59.4%). Heifers had lower PR if they were <14.6 mo of age (48.9 vs. 75%) or weighed <380 kg (47.4 vs. 70.8%). Although no significance differences in PR were observed between treatments in cows or heifers, DIM in cows and age and weight in heifers affected PR.Key words: Ovsynch, presynchronization, gonadotropin-releasing hormone, dairy heifer, dairy cow, timed artificial insemination

Variations in adequate levothyroxine replacement therapy in patients with different causes of hypothyroidism

OBJECTIVE

To compare the levothyroxine replacement dose in 181 patients with various causes of hypothyroidism.

METHODS

We analyzed the dose of levothyroxine used in the following five patient groups: (1) 37 patients with hypothyroidism after radioiodine therapy for Graves' thyrotoxicosis who were receiving a stable (for at least 4 years) replacement dose (mean time after 131 I therapy, 11.3 years); (2) 36 patients with Hashimoto's hypothyroidism (chronic autoimmune thyroiditis with a goiter or positive test results for antithyroid antibodies); (3) 36 patients with central hypothyroidism; (4) 36 patients with hypothyroidism after near-total thyroidectomy and 131 I therapy for thyroid carcinoma with negative total-body 131 I scans who were euthyroid when receiving levothyroxine; and (5) 36 patients with atrophic thyroiditis (no goiter and negative test results for antithyroid antibodies). Adequacy of levothyroxine replacement dose was defined as a normal thyrotropin level and clinical euthyroidism in patients with primary hypothyroidism and a serum free thyroxine index in the upper half of the normal range in conjunction with clinical euthyroidism in patients with central hypothyroidism.

RESULTS

The mean (+/- standard error of the mean) replacement dosage of levothyroxine (mg/kg per day) in patients with atrophic thyroiditis (1.26 +/- 0.07) was lower (P<0.05) than in patients with Hashimoto's hypothyroidism (1.59 +/- 0.07) and those with hypothyroidism after radioiodine therapy (1.56 +/- 0.05). These doses, in turn, were lower (P<0.01) than those in patients with central hypothyroidism (1.88 +/- 0.10) or euthyroid thyroid carcinoma (2.08 +/- 0.07). In a separate analysis, the levothyroxine dose in 43 patients with hypothyroidism after 131 I treatment was evaluated serially over time. The mean levothyroxine dosage increased from 0.87 +/- 0.12 at 6 months after 131 I therapy to 1.57 +/- 0.09 at 7 years (P<0.001). The serum thyrotropin concentration (in mU/mL) during levothyroxine therapy in patients with central hypothyroidism (0.31 +/- 0.08) was lower (P<0.01) than in patients with hypothyroidism after 131 I therapy (1.69 +/- 0.37), Hashimoto's hypothyroidism (1.39 +/- 0.20), atrophic thyroiditis (1.86 +/- 0.22), and euthyroid thyroid carcinoma (1.48 +/- 0.26).

CONCLUSION

The levothyroxine replacement dose varies with the cause of the hypothyroidism.

SpikeCell: a deterministic spiking neuron

We present a model of spiking neuron that emulates the output of the usual static neurons with sigmoidal activation functions. It allows for hardware implementations of standard feedforward networks, trained off-line with any classical learning algorithm (i.e. back-propagation and its variants). The model is validated on hand-written digits recognition, and image classification tasks. A digital architecture is proposed and evaluated. The area needed for implementing the spiking neuron on a chip is 10 times smaller than that for the corresponding static neuron. The accuracy of the network's output increases with time, and reaches that of the emulated static neural network after an adequate integration period. Single errors in the spike trains, or interruption of the relaxation process, due for example to irradiation in harsh environments, are harmless.

A model for the emergence of adaptive subsystems

We investigate the interaction of learning and evolution in a changing environment. A stable learning capability is regarded as an emergent adaptive system evolved by natural selection of genetic variants. We consider the evolution of an asexual population. Each genotype can have 'fixed' and 'flexible' alleles. The former express themselves as synaptic connections that remain unchanged during ontogeny and the latter as synapses that can be adjusted through a learning algorithm. Evolution is modelled using genetic algorithms and the changing environment is represented by two optimal synaptic patterns that alternate a fixed number of times during the 'life' of the individuals. The amplitude of the change is related to the Hamming distance between the two optimal patterns and the rate of change to the frequency with which both exchange roles. This model is an extension of that of Hinton and Nowlan in which the fitness is given by a probabilistic measure of the Hamming distance to the optimum. We find that two types of evolutionary pathways are possible depending upon how difficult (costly) it is to cope with the changes of the environment. In one case the population loses the learning ability, and the individuals inherit fixed synapses that are optimal in only one of the environmental states. In the other case a flexible subsystem emerges that allows the individuals to adapt to the changes of the environment. The model helps us to understand how an adaptive subsystem can emerge as the result of the tradeoff between the exploitation of a congenital structure and the exploration of the adaptive capabilities practised by learning.

Statistical mechanics of learning with soft margin classifiers

We study the typical learning properties of the recently introduced soft margin classifiers (SMCs), learning realizable and unrealizable tasks, with the tools of statistical mechanics. We derive analytically the behavior of the learning curves in the regime of very large training sets. We obtain exponential and power laws for the decay of the generalization error towards the asymptotic value, depending on the task and on general characteristics of the distribution of stabilities of the patterns to be learned. The optimal learning curves of the SMCs, which give the minimal generalization error, are obtained by tuning the coefficient controlling the trade-off between the error and the regularization terms in the cost function. If the task is realizable by the SMC, the optimal performance is better than that of a hard margin support vector machine and is very close to that of a Bayesian classifier.

Endothelial function during stimulation of renin-angiotensin system by low-sodium diet in humans

We examined whether physiological stimulation of the endogenous renin-angiotensin system results in impaired endothelium-dependent vasodilatation in forearm resistance vessels of healthy subjects and whether this impairment can be prevented by angiotensin II type 1 receptor blockade. A low-sodium diet was administered to 27 volunteers who were randomized to concomitant treatment with losartan (100 mg once daily) or matched placebo in a double-blind fashion. Forearm blood flow was assessed by venous occlusion plethysmography at baseline and after 5 days. Endothelium-dependent and -independent vasodilation was assessed by intra-arterial infusion of methacholine and verapamil, respectively. The low-sodium diet resulted in significantly decreased urine sodium excretion (placebo: 146 +/- 64 vs. 10 +/- 9 meq/24 h, P < 0.001; losartan: 141 +/- 56 vs. 14 +/- 14 meq/24 h, P < 0.001) and increased plasma renin activity (placebo: 1.0 +/- 0.5 vs. 5.0 +/- 2.5 ng x ml(-1) x h(-1), P < 0.001; losartan: 3.8 +/- 7.2 vs. 19.1 +/- 11.2 ng x ml(-1) x h(-1), P = 0.006) in both the losartan and placebo groups. With the baseline study as the reference, the diet intervention was not associated with any significant change in endothelium-dependent vasodilation to methacholine in either the placebo (P = 0.74) or losartan (P = 0.40) group. We conclude that short-term physiological stimulation of the renin-angiotensin system does not cause clinically significant endothelial dysfunction. Losartan did not influence endothelium-dependent vasodilation in humans with a stimulated renin-angiotensin system.

Ascorbate restores endothelium-dependent vasodilation impaired by acute hyperglycemia in humans

BACKGROUND

Endothelium-dependent vasodilation is impaired in patients with insulin-dependent and non-insulin-dependent diabetes mellitus and restored by vitamin C administration, implicating a causative role for oxidant stress. Hyperglycemia per se attenuates endothelium-dependent vasodilation in healthy subjects. Accordingly, this study investigated whether impaired endothelium-dependent vasodilation caused by hyperglycemia in nondiabetic humans is restored by administration of the antioxidant vitamin C.

METHODS AND RESULTS

Endothelium-dependent vasodilation was measured by incremental brachial artery administration of methacholine chloride (0.3 to 10 microg/min) during euglycemia, after 6 hours of hyperglycemia (300 mg/dL) created by dextrose (50%) intra-arterial infusion, and with coadministration of vitamin C (24 mg/min) during hyperglycemia. Endothelium-dependent vasodilation was significantly diminished by hyperglycemia (P:=0.02 by ANOVA) and restored by vitamin C (P:=0.04). In contrast, endothelium-dependent vasodilation was not affected by equimolar infusions of mannitol, with and without vitamin C coinfusion (P:=NS). Endothelium-independent vasodilation was measured by incremental infusion of verapamil chloride (10 to 300 microg/min) without and with coadministration of N:(G)-monomethyl-L-arginine (L-NMMA). In the absence of L-NMMA, endothelium-independent vasodilation was not significantly altered during hyperglycemia (P:=NS) but was augmented by vitamin C (P:=0.04). The coadministration of L-NMMA eliminated the vitamin C-related augmentation in verapamil-mediated vasodilation.

CONCLUSIONS

Vitamin C administration restores endothelium-dependent vasodilation impaired by acute hyperglycemia in healthy humans in vivo. These findings suggest that hyperglycemia may contribute in part to impaired vascular function through production of superoxide anion.

Successful anticoagulation with hirudin in a patient with mesenteric venous thrombosis and multiple coagulation abnormalities

A case of multiple thrombotic diatheses discovered in the setting of mesenteric venous infarction is discussed. The patient had deficiencies of protein C, protein S, antithrombin III; was heterozygous for factor V Leiden; and had polycythemia vera. Adequate anticoagulation could not be established with heparin administration and hirudin was used. The diagnosis of mesenteric venous infarction, thrombotic tendency of multiple coagulation diatheses, and use of hirudin are discussed.

A model for the interaction of learning and evolution

We present a simple model in order to discuss the interaction of the genetic and behavioral systems throughout evolution. This considers a set of adaptive perceptrons in which some of their synapses can be updated through a learning process. This framework provides an extension of the well-known Hinton and Nowlan model by blending together some learning capability and other (rigid) genetic effects that contribute to the fitness. We find a halting effect in the evolutionary dynamics, in which the transcription of environmental data into genetic information is hindered by learning, instead of stimulated as is usually understood by the so-called Baldwin effect. The present results are discussed and compared with those reported in the literature. An interpretation is provided of the halting effect.

Generalization properties of finite-size polynomial support vector machines

The learning properties of finite-size polynomial support vector machines are analyzed in the case of realizable classification tasks. The normalization of the high-order features acts as a squeezing factor, introducing a strong anisotropy in the patterns distribution in feature space. As a function of the training set size, the corresponding generalization error presents a crossover, more or less abrupt depending on the distribution's anisotropy and on the task to be learned, between a fast-decreasing and a slowly decreasing regime. This behavior corresponds to the stepwise decrease found by Dietrich et al. [Phys. Rev. Lett. 82, 2975 (1999)] in the thermodynamic limit. The theoretical results are in excellent agreement with the numerical simulations.

Efficient adaptive learning for classification tasks with binary units

This article presents a new incremental learning algorithm for classification tasks, called NetLines, which is well adapted for both binary and real-valued input patterns. It generates small, compact feedforward neural networks with one hidden layer of binary units and binary output units. A convergence theorem ensures that solutions with a finite number of hidden units exist for both binary and real-valued input patterns. An implementation for problems with more than two classes, valid for any binary classifier, is proposed. The generalization error and the size of the resulting networks are compared to the best published results on well-known classification benchmarks. Early stopping is shown to decrease overfitting, without improving the generalization performance.

Sodium balance modulates thirst in normal man

Several lines of evidence suggest that angiotensin II (AII) plays an important physiologic role in the control of thirst in laboratory animals but a conflicting one in humans. Sodium (Na+) balance plays a key role in the control of the renin-angiotensin system, but studies assessing the effect of sodium balance on thirst perception in humans are limited at best. To address this question, we studied the relationship between thirst perception and plasma osmolality during 5% saline infusion (.08 ml/kg/min x 120 min) in 5 healthy volunteers while in metabolic balance on both a 10 mEq. sodium (LS) and 200 mEq. sodium (HS) diet with and without infusion of AII (5 ng/kg/min). Thirst perception was quantified using a linear visual analogue scale. The relationship between serum Na+ (a measure of osmolality) and thirst perception was analyzed using linear regression. The mean x-intercept ([Na+] mEq/l) which represents the osmotic threshold to thirst was 138.2 +/- 0.5 in LS vs 140.7 +/- 0.8 in HS, p < 0.05. We conclude that the osmotic threshold for thirst is lower in LS (high endogenous AII) vs HS (low endogenous AII). There was no evidence for substantial extracellular volume change in HS vs LS with no significant differences in weight, hematocrit or total serum protein. Acute AII infusion did not result in changes in slope or x-intercept, but the pressor response to exogenous AII may have inhibited its dipsogenic effect (as has been shown in animal studies). These data suggest a physiologic role of sodium balance (possibly mediated via endogenous AII) in the control of thirst in normal humans.

Learning and generalization with Minimerror, a temperature-dependent learning algorithm

We study the numerical performances of Minimerror, a recently introduced learning algorithm for the perceptron that has analytically been shown to be optimal both on learning linearly and nonlinearly separable functions. We present its implementation on learning linearly separable boolean functions. Numerical results are in excellent agreement with the theoretical predictions.

Nonmodulating trait may precede the development of hypertension

The nonmodulating trait thought to explain development of hypertension in 25 to 35% of patients, is characterized by abnormal angiotensin II (AII)-mediated control of aldosterone release and renal blood flow (RBF). Some data support the possibility that nonmodulation is an inherited trait, but others argue that it is an acquired epiphenomenon of the hypertensive state. We report the first case of a normotensive patient with nonmodulation who subsequently developed frank hypertension. Patient RR was studied on six occasions over a 5-year period, two while normotensive, four while hypertensive. This patient consistently demonstrated an abnormally low plasma aldosterone response to AII (3 ng/kg/min) on a low salt (10 mEq sodium) diet while both normotensive and hypertensive. A consistently abnormally depressed RBF response to AII on a high salt (150 to 200 mEq sodium) diet as well as a depressed RBF increment when the diet was changed from low salt to high salt were also noted. Thus, RR demonstrated nonmodulation by multiple criteria while both normotensive and hypertensive. We conclude that the nonmodulating trait may be a heritable defect that leads to the development of hypertension and is not an epiphenomenon.

Qualitative and quantitative differences in the pathways of extrathyroidal triiodothyronine generation between euthyroid and hypothyroid rats

Propylthiouracil (PTU) in maximally inhibitory doses for liver and kidney iodothyronine 5'-deiodinase activity (5'D-I), reduces extrathyroidal T4 to T3 conversion by only 60-70% in euthyroid rats. A second pathway of T4 to T3 conversion (5'D-II) has been found in pituitary, central nervous system, and brown adipose tissue. 5'D-II is insensitive to PTU and increases in hypothyroidism, whereas 5'D-I decreases in hypothyroid rats. Thyroxine (T4) and triiodothyronine (T3) kinetics were assessed in euthyroid and thyroidectomized rats by noncompartmental analysis after injecting [125I]T4 and [131I]T3. Neither the volume of distribution nor the rate of fractional removal of plasma T4 was affected by the thyroid status, but the fractional removal rate of T3 was approximately 50% reduced in hypothyroid rats (P less than 0.001). Fractional T4 to T3 conversion was 22% in euthyroid and 26% in hypothyroid rats. In euthyroid rats, sufficient PTU to inhibit liver and kidney 5'D-I greater than 90% reduced serum [125I]T3 after [125I]T4 (results given as percent dose per milliliter X 10(-3) +/- SEM): 4 h, control 16 +/- 2 vs. PTU 4 +/- 1, P less than 0.005, and 22 h, control 6.4 +/- 0.4 vs. PTU 3.6 +/- 0.7, P less than 0.025. In thyroidectomized rats, the same dose of PTU also inhibited 5'D-I in liver and kidney, but had no effect on the generation of serum [125I]T3 from [125I]T4. Similarly, after 1 microgram T4/100 g bw was given to thyroidectomized rats, serum T3 (radioimmunoassay) increased by 0.30 +/- 0.6 ng/ml in controls and 0.31 +/- 0.09 ng/ml in PTU-treated rats. However, when the dose of T4 was increased to 2-10 micrograms/100 g bw, PTU pretreatment significantly reduced the increment in serum T3. T3 clearance was not affected by PTU in hypothyroid rats. The 5'D-II in brain, pituitary, and brown adipose tissue was reduced to less than or equal to 60% of control by 30 micrograms/100 g bw reverse T3 (rT3), an effect that lasted for at least 3 h after rT3 had been cleared. In rT3-pretreated thyroidectomized rats, the generation of [125I]T3 from tracer [125I]T4 was reduced in the serum: 6 +/- 1 vs. 12 +/- 1 X 10(-3)% dose/ml, P less than 0.01, during this 3-h period. We conclude that virtually all the T3 produced from low doses of exogenous T4 given to hypothyroid rats is generated via a PTU-insensitive pathway, presumably catalyzed by the 5'D-II. This is a consequence of the enhanced activity of this low Km enzyme together with the concomitant decrease in the hepatic and renal 5'D-I characteristic of the hypothyroid state. The results indicate that in some circumstances, 5D-II activity may contribute to the extracellular, as well as intracellular, T3 pool.

Captopril enhances vascular and adrenal responsiveness to angiotensin II in essential hypertension

The converting-enzyme inhibitor captopril (25-50 mg orally every 6 h for 66 h) was used to dissociate the circulating levels of angiotensin II (ANG II) from changes in sodium balance in 11 patients with normal renin essential hypertension on 10 mmol of sodium/day intake. Pressor, renal vascular and adrenal responses to graded infusions of ANG II (0.3, 1 and 3 pmol kg-1 min-1) were measured before and after captopril administration. Systemic vascular responses were assessed by measuring diastolic blood pressure (DBP), renovascular responses by measuring p-aminohippurate (PAH) clearance and adrenal responses by measuring plasma aldosterone. After receiving captopril for 66 h the hypertensive subjects showed a significantly (P less than 0.004) enhanced blood pressure response to the infused ANG II but not to noradrenaline when compared with the response before captopril. ANG II (3 pmol kg-1 min-1) also produced a significantly (P less than 0.03) greater reduction in PAH clearance after (-194 +/- 40 ml/min) compared with before (-104 +/- 15 ml/min) captopril. These results suggest that the responsiveness to ANG II in these two target tissues is determined by the circulating ANG II level. In the adrenal gland the aldosterone responses to ANG II also were significantly greater after (P less than 0.01) than before captopril (increment at 3 pmol kg-1 min-1: 660 +/- 88 vs 381 +/- 94 pmol/l). These results are in distinct contrast with the responses previously reported for normotensive subjects and support the hypothesis that the regulation of aldosterone secretion is altered in subjects with essential hypertension.

Dopaminergic blockade of the renin-angiotensin-aldosterone system: effect of high and low sodium intakes

Recent investigations suggest that dopamine inhibits aldosterone secretion. To test the hypothesis that dopamine contributes to the reduced aldosterone secretion on a high sodium intake, eight normal subjects were studied in metabolic balance on both 200 and 10 mmol sodium diets. On each diet, the subjects received a constant 4 h intravenous infusion of the dopamine antagonist, metoclopramide (MCP). Although MCP significantly increased plasma aldosterone (PA) throughout the infusion on both diets, the maximum increment in PA was greater on the low (37 +/- 5 ng/dl) than on the high (14 +/- 4 ng/dl) sodium intake (P less than 0.02). The greater response on the low sodium intake could not be ascribed to changes in potassium, cortisol or ACTH. However, plasma renin activity (PRA) and angiotensin II (AII) levels were significantly (P less than 0.01) increased by MCP while on the low but not the high sodium intake. We conclude that the rise in PA while on a high sodium intake reflects dopaminergic antagonism by MCP directly at the level of the adrenal gland. On the low sodium intake, the enhanced PA response to MCP probably reflects both a direct adrenal effect and an indirect effect mediated via activation of the renin-angiotensin system.

Dopaminergic modulation of aldosterone responsiveness to angiotensin II with changes in sodium intake

The aldosterone response to infused angiotensin II (AII) is blunted by sodium (Na) loading. Since dopamine levels increase on a high Na diet and dopamine can inhibit aldosterone secretion, it is possible that dopamine mediates the blunted aldosterone secretion in this setting. To test this hypothesis, we assessed whether the dopamine antagonist, metoclopramide (MCP) would enhance the aldosterone response to infused AII. Six normal subjects received graded infusions of AII when they were in metabolic balance on diets containing both 10 and 200 meq Na/day (control infusions). The infusions were then repeated (on the same diets) during the administration of MCP (0.1 mg/kg iv bolus, then 0.05 mg/kg . h). During the control AII infusions, the aldosterone response to the highest dose of AII was significantly less on the 200 meq Na intake than on 10 meq (plasma aldosterone levels increased 17 +/- 5 vs. 30 +/- 8 ng/dl respectively; P less than 0.01). However, MCP administration eliminated this difference in aldosterone responsiveness by significantly enhancing (P less than 0.02) the response to infused AII during the 200 meq Na intake (plasma aldosterone increment of 25 +/- 9 ng/dl). This effect of MCP was limited to the adrenal response to AII: on a given Na intake, the mean blood pressure response to AII was similar both with and without concomitant MCP. These results suggest that dopamine may be an important regulator of the alterations in aldosterone responsiveness to AII that occur during changes in dietary sodium intake.

Thyroid disease in progressive systemic sclerosis: increased frequency of glandular fibrosis and hypothyroidism

A series of patients with fatal progressive systemic sclerosis was reviewed with regard to pathologic, clinical, and serologic evidence of thyroid disease. Histologic evidence of severe fibrosis of the thyroid gland was found significantly more frequently in 56 progressive systemic sclerosis cases (14%) compared to an age and sex matched control autopsy series (2%) from the same institution. Based on determination of serum free thyroxine, free triiodothyroxine (T3), thyroid stimulating hormone, and reverse T3, 27 patients were classified as euthyroid (11), euthyroid sick (9), and hypothyroid (7). Patients with hypothyroidism more frequently had subcutaneous calcinosis. Raynaud's phenomenon, esophageal hypomotility, sclerodactyly, and multiple telangiectasias (the CREST syndrome variant of progressive systemic sclerosis); all thyroid glands from the hypothyroid patients had fibrosis, but lymphocytic infiltration was an infrequent finding. Six hypothyroid patients had high titers of serum antithyroid antibodies, suggesting autoimmune thyroid disease. Thyroid gland fibrosis and hypothyroidism, possibly of autoimmune pathogenesis, are thus frequent and often unsuspected findings in progressive systemic sclerosis.

Phencyclidine: effects on motor activity and brain biogenic amines in the guinea pig

Previous reports suggesting that the behavioral response of the guinea pig to phencyclidine (PCP) administration is more similar to the effects of PCP observed in higher animals than those observed in mice and rats prompted us to investigate the effects of PC on spontaneous motor activity and brain biogenic amine levels in the guinea pig. Doses of 2.5 and 5.0 mg/kg PCP were found to significantly elevate spontaneous motor activity; however, 7.5 mg/kg PCP produced highly variable results which were not significantly different from control. The concentrations of tryptophan, serotonin, 5-hydroxyindoleacetic acid, and norepinephrine were measured in the forebrain and hindbrain of previously drug naive animals 30 min after administration of 5 mg/kg PCP. As compared to saline injected control animals, PCP was observed to have no effect on any of the neurochemical determinants measured. Contrary to previous reports, these data suggest that PCP produces behavioral effects in the guinea pig which are not unlike those observed in mice and rats. Furthermore, the effects which we report on spontaneous motor activity are not related to changes in the regional concentration of any of the neurochemical variables which were measured.