Impact of acute consumption of beverages containing plant-based or alternative sweetener blends on postprandial appetite, food intake, metabolism, and gastro-intestinal symptoms: Results of the SWEET beverages trial

Project SWEET examined the barriers and facilitators to the use of non-nutritive sweeteners and sweetness enhancers (hereafter "S&SE") alongside potential risks/benefits for health and sustainability. The Beverages trial was a double-blind multi-centre, randomised crossover trial within SWEET evaluating the acute impact of three S&SE blends (plant-based and alternatives) vs. a sucrose control on glycaemic response, food intake, appetite sensations and safety after a carbohydrate-rich breakfast meal. The blends were: mogroside V and stevia RebM; stevia RebA and thaumatin; and sucralose and acesulfame-potassium (ace-K). At each 4 h visit, 60 healthy volunteers (53% male; all with overweight/obesity) consumed a 330 mL beverage with either an S&SE blend (0 kJ) or 8% sucrose (26 g, 442 kJ), shortly followed by a standardised breakfast (∼2600 or 1800 kJ with 77 or 51 g carbohydrates, depending on sex). All blends reduced the 2-h incremental area-under-the-curve (iAUC) for blood insulin (p < 0.001 in mixed-effects models), while the stevia RebA and sucralose blends reduced the glucose iAUC (p < 0.05) compared with sucrose. Post-prandial levels of triglycerides plus hepatic transaminases did not differ across conditions (p > 0.05 for all). Compared with sucrose, there was a 3% increase in LDL-cholesterol after stevia RebA-thaumatin (p < 0.001 in adjusted models); and a 2% decrease in HDL-cholesterol after sucralose-ace-K (p < 0.01). There was an impact of blend on fullness and desire to eat ratings (both p < 0.05) and sucralose-acesulfame K induced higher prospective intake vs sucrose (p < 0.001 in adjusted models), but changes were of a small magnitude and did not translate into energy intake differences over the next 24 h. Gastro-intestinal symptoms for all beverages were mostly mild. In general, responses to a carbohydrate-rich meal following consumption of S&SE blends with stevia or sucralose were similar to sucrose.

Acute and repeated impact of sweeteners and sweetness enhancers in solid and semi-solid foods on appetite: protocol for a multicentre, cross-over, RCT in people with overweight/obesity - the SWEET Project

INTRODUCTION

Intake of free sugars in European countries is high and attempts to reduce sugar intake have been mostly ineffective. Non-nutritive sweeteners and sweetness enhancers (S&SEs) can maintain sweet taste in the absence of energy, but little is known about the impact of acute and repeated consumption of S&SE in foods on appetite. This study aims to evaluate the effect of acute and repeated consumption of two individual S&SEs and two S&SE blends in semisolid and solid foods on appetite and related behavioural, metabolic and health outcomes.

METHODS AND ANALYSIS

A work package of the SWEET Project; this study consists of five double-blind randomised cross-over trials which will be carried out at five sites across four European countries, aiming to have n=213. Five food matrices will be tested across three formulations (sucrose-sweetened control vs two reformulated products with S&SE blends and no added sugar). Participants (body mass index 25-35 kg/m²; aged 18-60 years) will consume each formulation for 14 days. The primary endpoint is composite appetite score (hunger, inverse of fullness, desire to eat and prospective food consumption) over a 3-hour postprandial incremental area under the curve during clinical investigation days on days 1 and 14.

ETHICS AND DISSEMINATION

The trial has been approved by national ethical committees and will be conducted in accordance with the Declaration of Helsinki. Results will be published in international peer-reviewed open-access scientific journals. Research data from the trial will be deposited in an open-access online research data archive.

TRIAL REGISTRATION NUMBER

NCT04633681.

Reference microarchitectural values measured by HR-pQCT in a Franco-Swiss cohort of young adult women

Bone microarchitecture assessed by high-resolution peripheral quantitative computed tomography varies across populations of different origin. The study presents a reference dataset of microarchitectural parameters in a homogeneous group of participants aged within 22-27 range determined by a discriminant analysis of a larger cross-sectional cohort of 339 women.

INTRODUCTION

High-resolution peripheral quantitative computed tomography (HR-pQCT) non-invasively measures three-dimensional bone microarchitectural parameters and volumetric bone mineral density. Previous studies established normative reference HR-pQCT datasets for several populations, but there were few data assessed in a reference group of young women with Caucasian ethnicity living in Western Europe. It is important to obtain different specific reference dataset for a valid interpretation of cortical and trabecular microarchitecture data. The aim of our study was to find the population with the most optimal bone status in order to establish a descriptive reference HR-pQCT dataset in a young and healthy normal-weight female cohort living in a European area including Geneva, Switzerland, Lyon and Saint-Etienne, France.

METHODS

We constituted a cross-sectional cohort of 339 women aged 19-41 years with a BMI > 18 and < 30 kg/m². All participants had HR-pQCT measurements at both non-dominant distal radius and tibia sites.

RESULTS

We observed that microarchitectural parameters begin to decline before the age of 30 years. Based on a discriminant analysis, the optimal bone profile in this population was observed between the age range of 22 to 27 years. Consequently, we considered 43 participants aged 22-27 years to establish a reference dataset with median values and percentiles.

CONCLUSION

This is the first study providing reference values of HR-pQCT measurements considering specific age bounds in a Franco-Swiss female cohort at the distal radius and tibia sites.

Low-energy sweeteners and body weight: a citation network analysis

OBJECTIVE

Reviews on the relationship of low-energy sweeteners (LES) with body weight (BW) have reached widely differing conclusions. To assess possible citation bias, citation analysis was used to quantify the relevant characteristics of cited articles, and explore citation patterns in relation to review conclusions.

DESIGN

A systematic search identified reviews published from January 2010 to March 2020. Different characteristics (for example, type of review or research, journal impact factor, conclusions) were extracted from the reviews and cited articles. Logistic regression was used to estimate likelihood of articles with particular characteristics being cited in reviews. A qualitative network analysis linked reviews sub-grouped by conclusions with the types of articles they cited.

MAIN OUTCOME MEASURES

(OR; 95% CI) for likelihood that articles with particular characteristics were cited as evidence in reviews.

RESULTS

From 33 reviews identified, 183 different articles were cited (including other reviews). Narrative reviews were 62% less likely to be cited than systematic reviews with meta-analysis (OR 0.38; 0.16 to 0.86; p=0.03). Likelihood of being cited was higher for evidence on children than adults (OR 2.27; 1.59 to 3.25; p<0.0001), and with increased journal impact factor (OR 1.15; 1.00 to 1.31; p=0.04). No other factors were statistically significant in the main analysis, and few factors were significant in subgroup analyses. Network analysis showed that reviews concluding a beneficial relationship of LES with BW cited mainly randomised controlled trials, whereas reviews concluding an adverse relationship cited mainly observational studies.

CONCLUSIONS

Overall reference to the available evidence across reviews appears largely arbitrary, making citation bias likely. Differences in the conclusions of individual reviews map onto different types of evidence cited. Overall, inconsistent and selective use of the available evidence may account for the diversity of conclusions in reviews on LES and BW.

TRIAL REGISTRATION NUMBER

Prior to data analysis, the protocol was registered with the Open Science Framework (https://osf.io/9ghws).

Microsatellite profile in hormonal receptor genes associated with breast cancer

Given that breast cancer is depending on multiple hormonal influences, the nuclear receptors, estrogen receptor alpha, estrogen receptor beta and androgen receptor, are candidates for cancer susceptibility markers. We conducted an association study in a case-control population (139 cases and 145 controls) by genotyping three potentially functional microsatellites (TA)n, (CA)n and (CAG)n in the ERa, ERb and AR genes respectively. For (CAG)n polymorphism, a significant difference was observed using a cut-off 15 repeats CAG between genotypes short-short/short-long/long-long in cases and control subjects (p = 0.009) and also between the distribution of short/long allele in the two groups of individuals (p = 0.001). Genotypes comprising one or two short (CAG)n sequences had higher risk of breast cancer compared to genotypes with two long allele (odds ratio = 1,93; confidence interval = 1.05-3.55; p = 0.03). No significant difference was observed in allele frequency or in short/long allele percentage for (CA)n or (TA)n polymorphism (cut-off 22 CA and 19 TA repeats), neither in genotype frequencies (short-short, short-long or long-long). When the three microsatellite genotype were taken in analysis, the profile short CA-long TA-short CAG could clearly discriminate between cases and controls (p = 0.006). Also, this combined genotype profile has greater predictive values for breast cancer than (CAG)n genotype alone (predictive positive value 57,1% versus 53,7% and predictive negative value 53% versus 23% respectively). Our results sustain a polygenic model of breast cancer with gene-gene interactions; combined effects of three low-risk polymorphisms conferred significant genetic predisposition. Genotyping hormonal receptor genes ERa, ERb and AR could be a useful genetic marker for defining disease risk.

A model of microbial contamination of a water reservoir

A three year record of daily fecal coliform counts in a Massachusetts water reservoir has the appearance of an irregular time series punctuated by outbursts of varying duration. The pattern is described in terms of a probabilistic model where the fluctuations in the 'regular' and 'explosive' regimes are governed by two sets of probabilities. It has been assumed that the random oscillations has a lognormal distribution, and that once an explosion threshold has been exceeded the increments or decrements in the population size have fixed probability distributions. The threshold for triggering an outburst was estimated by examining the randomness of the autocorrelation function of the record after it is filtered to eliminate peaks of progressively increasing magnitude. Once the threshold has been identified, the mean and standard deviation of the underlying lognormal distribution could be estimated directly from remains found in the record after all the peaks were removed. The probabilities of an increment and decrement during the outbursts and their relative magnitudes could also be estimated using simple formulas. These estimated parameter values were then used to generate realistic records with known threshold levels, which were subsequently used to assess the procedure's feasibility and sensitivity.

Comparison of axial and flexural stresses in lordosis and three buckled configurations of the cervical spine

OBJECTIVE

To calculate and compare combined axial and flexural stresses in lordosis versus buckled configurations of the sagittal cervical curve.

DESIGN

Digitized measurements from lateral cervical radiographs of four different shapes were used to calculate axial loads and bending moments on the vertebral bodies of C2-C7.Background. Osteoarthritis and spinal degeneration are factors in neck and back pain. Calculations of stress in clinically occurring configurations of the sagittal cervical spine are rare.

METHODS

Center of gravity of the head (inferior-posterior sella turcica) and vertebral body margins were digitized on four different lateral cervical radiographs: lordosis, kyphosis, and two "S"-shapes. Polynomials (seventh degree) and stress concentrations on the concave and convex margins were derived for the shape of the sagittal cervical curvatures from C1 to T1. Moments of inertia were determined from digitizing and the use of an elliptical shell model of cross-section. Moment arms from a vertical line through the center of gravity of the head to the atlas and scaled neck extensor moment arms from the literature were used to compute the vertical component of extensor muscle effort. Segmental lever arms were calculated from a vertical line through C1 to each vertebra.

RESULTS

In lordosis, anterior and posterior stresses in the vertebral body are nearly uniform and minimal. In kyphotic areas, combined stresses changed from tension to compression at the anterior vertebral margins and were very large (6-10 times as large in magnitude) compared to lordosis. In kyphotic areas at the posterior vertebral body, the combined stresses changed from compression (in lordosis) to tension.

CONCLUSIONS

The stresses in kyphotic areas are very large and opposite in direction compared to a normal lordosis. This analysis provides the basis for the formation of osteophytes (Wolff's Law) on the anterior margins of vertebrae in kyphotic regions of the sagittal cervical curve. This indicates that any kyphosis is an undesirable configuration in the cervical spine. Relevance. Osteophytes and osteoarthritis are found at areas of altered stress and strain. Axial and flexural stresses at kyphotic areas in the sagittal cervical spine are abnormally high.

On modeling the irregular fluctuations in microbial counts

Daily or other periodic microbial counts in many foods, particularly ground meats, poultry, and raw milk, show an irregular fluctuating pattern. The cause of the fluctuations is the interplay of many random factors that tend to promote or inhibit microbial growth. Therefore, the actual size of a microbial population can vary randomly around a typical level or around a trend determined, for example, by seasonal variations or changing sanitary conditions. Fluctuations around a fixed level can often be modeled as a sequence of independent counts having a lognormal or other parametric distribution. The independence of the counts and the type of distribution can be established by standard statistical tests. Once selected, the distribution function can be used to estimate the probability of encountering a population in any given size range. The model can be modified to describe sequences that include zero counts, which are the result of the organisms' absence, or of the failure of the method to detect them. In the case of fluctuations around a trend, a modified version of the model can be used to estimate the probability of deviations from the trend. A more thorough modification is required in order to account for fluctuating patterns that include outbursts of appreciable duration, like those caused by massive contamination of a water reservoir.

Calciuric response to an acute acid load in healthy subjects and hypercalciuric calcium stone formers

Excessive animal protein consumption is associated with a greater risk of occurrence of renal calcium stone, presumably because of the attendant endogenous acid production. Indeed, chronic acid load enhances urinary calcium excretion possibly through an increased bone calcium release. Because acute studies are best designed to elucidate the mechanism, renal or extra renal, underlying hypercalciuria in the setting of enhanced acid load, we examined the response of 9 healthy adults (8 males, 1 female, aged 38 +/- 3 years, weight 67 +/- 2 kg) and 34 hypercalciuric recurrent calcium stone formers (31 males, 3 females, aged 44 +/- 2 years, weight 72 +/- 2 kg), without any associated disease, to an oral acid load (NH4Cl 2 mmol/kg body wt). After an overnight fast, each patient and control was studied during one one-hour period before and three two-hour periods after their intake of the acid load. An additional group of four time-control subjects (4 males, aged 33 +/- 2 years, weight 66 +/- 2 kg) was studied as the experimental groups except that they did not receive the acid load. On baseline, the three groups exhibited similar glomerular filtration rates, net acid excretions, and plasma calcium and magnesium concentrations. However, fasting urine calcium and magnesium excretions were higher in hypercalciuric calcium stone formers than in healthy control or time-control subjects. In time-control subjects, plasma acid base status, net acid excretion, filtered loads of calcium and magnesium, and urinary calcium and magnesium excretions remained unchanged all over the study. By contrast, after the oral acute acid load, net acid excretion increased and urinary pH decreased similarly in patient and control groups; glomerular filtration rate did not change, as well as plasma calcium and magnesium concentrations. Nevertheless, urinary calcium and magnesium excretions markedly increased, in both groups, independently of changes in tubular sodium handling and in plasma parathyroid hormone concentration. The increase in urinary calcium and magnesium excretions that occurred in the absence of any change in the filtered load of calcium and magnesium was therefore mediated by a decrease in tubular calcium and magnesium reabsorption, independent of PTH, but dependent on changes in net acid excretion. A positive linear relationship between urinary calcium and magnesium excretions suggested that the target tubular site for acid load was the thick ascending limb of Henle's loop. Finally, a negative linear relationship was demonstrated between the acid load-induced increase in urinary calcium excretion and fasting urinary calcium excretion; indeed, the lowest calciuric responses were observed in patients with the highest fasting urinary calcium excretion. Thus there was no additional effect of the acid load-induced inhibition on intrinsic defect in tubular calcium reabsorption which suggests that the tubular target site for acid load and the site of calcium transport defect in idiopathic hypercalciuria may be the same.

Anorectal function in fluctuating (on-off) Parkinson's disease: evaluation by combined anorectal manometry and electromyography

Anorectal dysfunction and constipation are well recognized in Parkinson's disease and may reflect the direct involvement of the gastrointestinal tract by the primary Parkinson's disease process. We hypothesized, therefore, that anorectal function would alter in parallel with fluctuations in motor function related to on- and off-periods in Parkinson's disease, and employed combined anorectal manometry and electromyography to investigate anorectal function during both on- and off-periods in patients with Parkinson's disease. Manometric recordings revealed a deterioration in voluntary sphincter squeeze during off-periods (squeeze index, on versus off, mean +/- SEM: 46.4 +/- 11.1 versus 29.6 +/- 7.9 mm Hg, p < 0.05); correspondingly, simultaneous electromyographic (EMG) recordings showed poor recruitment of external anal sphincter and puborectalis muscles during off-periods. A hypercontractile ("paradoxical") rectosphincteric reflex response occurred during both on- and off-periods, and was associated with an increase in EMG activity in the external sphincter and/or the puborectalis muscle. These changes in manometric and EMG parameters paralleled changes in overall motor function. These findings provide further support for the involvement of the pelvic floor musculature in the Parkinson's disease process and also provide EMG correlates for some of the manometric abnormalities described in Parkinson's disease.

[Psychosocial characteristics of phenylketonuric women: birth defect prevention]

Women with phenylketonuria (PKU) are at high risk for having offspring with mental retardation, microcephaly, heart defects and low birth weight. These adverse outcomes can be prevented by a low-phenylalanine diet started before conception and continued throughout pregnancy. In view of the frequency of poor dietary compliance in women with PKU, a psychosocial model was developed that delineates developmental stages with specific behavioral goals for them to follow. In the present study 15 women with PKU over the age of 16 were followed for 3 years and compared to groups of their healthy acquaintances and of diabetic women. Structured interviews and standard questionnaires were used to study factors hypothesized as being related to the subjects' adjustment and to achievement of their PKU-related behavioral goals. After 1 year most of the PKU subjects were not planning a pregnancy, making their main behavioral goal the prevention of an unplanned pregnancy. Their knowledge of the risks of maternal PKU and family planning was unsatisfactory. PKU subjects had more conservative attitudes about sex and contraception than the controls. The psychosocial profile of PKU subjects pinpointed their special needs and indicated the kinds of specific intervention that might help them adhere to the recommended treatment and prevent birth defects in their offspring.

Model of the distribution and metabolism of the gonadotropin-releasing hormone (GnRH) agonist [D-Trp6,Des-Gly-NH2(10)]GnRH ethylamide in man

The kinetics of plasma immunoreactive [D-Trp6,Des-Gly-NH2(10)]GnRH ethylamide, a potent GnRH agonist, was assessed in nine normal adult men over a period of 24 h after a rapid sc injection of 1 or 10 micrograms peptide/kg BW. The specific RIA of the GnRH agonist is characterized by a minimum detectable dose of 5.0 +/- 0.5 pg peptide, while the midrange effective dose is 73 +/- 8 pg. The within- and between-assay coefficients of variation range from 2-7% and from 10-15%, respectively. When the volume of the central compartment is set proportional to the logarithm of the plasma concentration of the GnRH agonist, the time courses of both doses are statistically well represented by a two-compartment model to which a source compartment is added to represent the sc route of administration. The sc diffusion to plasma is 5 times faster than any other fractional transport rate of the model (5%/min). Disposal occurs at a maximum rate of 0.55%/min from the central compartment, which includes plasma, and 0.25%/min from the peripheral compartment. As simulated with the model, 90% of the steady state is reached 13 h and 45 min after the onset of a sc continuous infusion. A molecule spends, on the average, from 6 h to 9 h and 45 min in the whole organism; 30-50% of this period is accounted for by residence in the central compartment. The volume of the central compartment reaches 208 mL/kg BW, and the MCR is estimated at 1.18 mL/min.kg BW for a steady state of 1 ng/mL plasma. The plasma dynamics of [D-Trp6,Des-Gly-NH2(10)]GnRH ethylamide in men are at least 10 times slower than those reported for the natural GnRH, thus indicating the relevance of its clinical use in suppressive therapy of LH secretion.

Model of the distribution and metabolism of a GnRH superagonist in dogs

The plasma kinetics of [D-Trp6, des-Gly-NH2(10)]gonadotropin-releasing hormone (GnRH) ethylamide was assessed in eight dogs over a period of 8 h after rapid intravenous or subcutaneous injection. Each animal received doses of 0.2, 2, and 20 micrograms/kg body wt iv and 1 and 10 micrograms/kg body wt sc. A two-compartment structure, to which a source compartment was added to represent the subcutaneous route, adequately fits the five kinetics when the apparent volume of distribution follows a plasma concentration-dependent sigmoid function. Despite the nonlinearity, the apparent volume of distribution can be approximated by a constant value of 280 ml/kg body wt for the dynamics corresponding to the three lowest and more physiological doses. The metabolic clearance rate is 4.63 ml.min-1.kg body wt-1. The two exponential components that characterize the two-compartment structure are equal to 0.0348 +/- 0.0053 and 0.00470 +/- 0.00060 min-1, respectively. The agonist injected subcutaneously diffuses to plasma at a fractional rate of 0.0265 +/- 0.0029 min-1. Disposal occurs at a maximal rate of 0.017 and 0.0055 min-1 of the amount of agonist present in the central and peripheral compartments, respectively. The highest fractional exchange rate between compartments reaches 0.01 min-1. As simulated with the model, a continuous infusion of 4.63 ng.min-1.kg body wt-1 leads to a steady state of 1 ng/ml plasma; 90% of that level is reached 7 h after the onset of the subcutaneous input signal. The kinetics of plasma [D-Trp6, des-Gly-NH2(10)]GnRH ethylamide is many times slower than that of the native hormone and of the other GnRH agonists.

Group work with adolescent PKU girls and their mothers

Group therapy was the method chosen for working with PKU girls and their mothers in improving their knowledge of maternal PKU and the prevention of unplanned pregnancies. It was found effective in relieving anxiety, and the importance of including the mothers in the group was critical.

A model of the distribution and metabolism of corticotropin-releasing factor

The aim of this study is the selection of the number of compartments required for a model to represent the distribution and metabolism of corticotropin-releasing factor (CRF) in rats. The dynamics of labeled rat CRF were measured in plasma for seven rats after a rapid injection. The sampling schedule resulted from the combination of the two D-optimal sampling sets of times corresponding to both rival models. This protocol improved the numerical identifiability of the parameters and consequently facilitated the selection of the relevant model. A three-compartment model fits adequately to the seven individual dynamics and better represents four of them compared with the lower-order model. It was demonstrated, using simulations in which the measurement errors and the interindividual variability of the parameters are included, that his four-to-seven ratio of data sets is consistent with the relevance of the three-compartment model for every individual kinetic data set. Kinetic and metabolic parameters were then derived for each individual rat, their values being consistent with the prolonged effects of CRF on pituitary-adrenocortical secretion.

Piridoxilate-induced calcium oxalate calculi: a new drug-induced metabolic nephrolithiasis

During the last 4 years we collected 27 specimens of calcium oxalate nephrolithiasis in patients receiving long-term treatment with piridoxilate, a drug composed of an equimolar combination of glyoxylate and pyridoxine. The mean duration of treatment was 3.6 years (range 4 months to 10 years) and the mean daily dose was 580 mg. piridoxilate, which contained 160 mg. glyoxylate. Calculi often recurred, with an average number of 9.9 per patient, and an open operation, shock wave lithotripsy or percutaneous nephrolithotomy was required in 22 patients (81 per cent). Oxalate excretion was 727 +/- 246 mumol. per day while on the drug and 382 +/- 201 mumol. per day after the drug was withdrawn. Whewellite was the major component of calculi in all cases but the stones exhibited a peculiar morphological arrangement, with multiple small indentations and a fine mamillary structure. Freshly voided urine specimens contained unusual crystals, which on infrared spectroscopy were composed of calcium oxalate trihydrate, a variety of crystal never observed previously in human urine. Piridoxilate-induced calcium oxalate nephrolithiasis is a new variety of metabolic drug-induced nephrolithiasis. Our observations suggest that even large doses of pyridoxine may be unable to prevent the excessive production of oxalate from glyoxylate.

Distribution and metabolism of corticotropin-releasing factor in the rat

To develop a mathematical model of the distribution and metabolism of rat corticotropin-releasing factor (rCRF), the time course of 125I-labelled rCRF in plasma was measured in male Sprague-Dawley rats (i) following a rapid injection of 24 ng rCRF/100 g body weight (BW), or (ii) following a rapid injection of 424 ng rCRF/100 g BW, or (iii) during an infusion at a rate ranging from 0.28 to 0.73 ng rCRF X min-1 X 100 g BW-1. The comparison of the one-, two-, and three-compartment models shows that the two-pool structure fits better to the dynamics of CRF in plasma as measured in each rat. Following a rapid injection the decay curve occurs in a biphasic manner; the early phase of disappearance is 25 times faster than the late one. There is no significant difference between the estimates of the metabolic clearance rate following both amplitudes of injection (0.40 +/- 0.06 and 0.48 +/- 0.05 mL X min-1 X 100 g BW-1). The volume of the first pool, 16.8 +/- 1.1 mL/100 g BW, is four times larger than the plasma volume. It would thus appear that CRF is rapidly distributed from plasma into several tissues which are represented in the first pool of the model. The mean residence time of every CRF molecule in the second compartment, from the moment of secretion to its elimination, is from three to four times longer than in the first one. It stays, on average, between 140 min and 3 h in the system before an irreversible exit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocortical responses to corticotropin-releasing factor in the rat

The time course of plasma corticosterone was measured in male Sprague-Dawley rats whose endogenous release of ACTH had been blocked following rapid i.v. injections of doses ranging from 0.003 to 10 micrograms corticotropin-releasing factor (CRF) per rat and during i.v. infusions at rates ranging from 0.001 to 20 ng CRF X min-1 X 100 g body weight-1. The range of the dose-response curve, following rapid injection, extends from 0.01 to 0.37 micrograms CRF, whereas it extends over a 20 000-fold range from 0.001 to 20 ng CRF X min-1 X 100 g body weight-1 during a continuous infusion. The delayed response to a small rate of CRF could be ascribed to a relatively long time of residence of CRF in the plasma which implies that a relatively long period of time is required until a minimal plasma CRF concentration is reached after the onset of a continuous infusion of CRF at a small rate. When presented with a prolonged infusion of CRF at a large rate, the pituitary secretion of ACTH is rapidly turned on at a rate which exhibits the characteristics of a prolonged secretion at a constant large magnitude.

Malignant phenylketonuria due to defective synthesis of dihydrobiopterin

A defect in the synthesis of dihydrobiopterin was detected in an Arab girl, ascertained through high blood phenylalanine level on neonatal screening. An oral loading test with tetrahydrobiopterin (BH4) caused a significant fall in her blood phenylalanine and a rise in tyrosine concentrations. Her blood biopterin levels were low. In urine and cerebrospinal fluid (CSF) very high neopterin and low biopterin levels were observed. A deficiency of metabolites of neurotransmitters, serotonin and dopamine, was observed in CSF and urine. The patient was given replacement therapy of BH4, 5-hydroxytryptophan, and L-dopa with carbidopa starting from the age of 16 to 18 weeks. On this treatment the blood phenylalanine levels dropped to the desired range, while in urine and CSF a satisfactory rise of neurotransmitter metabolites was observed. In spite of this biochemical control, the patient developed neurological symptoms with myoclonic jerks and changes in muscle tone and presented severe cerebral damage with mental retardation. She died suddenly at the age of 38 weeks.

[Cell mediated immunity in a mercury nephrotic syndrome (author's transl)]

A case of extramembranous glomerulonephritis seen in a patient in contact with mercury diodide is reported. The responsibility of mercury in this occurrence of this nephropathy is confirmed by positive tests exploring cell mediated immunity. The other possible actions of mercury are described: modifications in renal tubular antigen, or in a tissue or serum protein, with antibody production and secondary apparition of immune complexes which deposit in the glomerules.

Adrenocortical responses to adrenocorticotrophin in the rat

The time course of plasma adrenocorticotrophin (ACTH), adrenal cyclic AMP, adrenal corticosterone, and plasma corticosterone was measured in male Sprague-Dawley rats whose endogenous release of ACTH had been blocked (1) following rapid injections of 100 and 300 ng ACTH/100 g body weight, i.v., (2) during prolonged infusions at rates of 1, 2, and 4 ng ACTH/min per 100 g body weight, and (3) after termination of 30-min infusions at rates extending from 0.06 to 8 ng ACTH/min per 100 g body weight. Following injections, the time course of the variables is similar to the one simulated from our models of adrenal cortical secretion, including the simulation of an intermediate variable of our models of the adrenal cortex cell which was presumed to correspond to cyclic AMP. However, during prolonged infusions there is an unexpected overshoot of adrenal cyclic AMP content whereas adrenal and plasma corticosterone concentrations rise to a steady-state value without overshoot. The total amount of cyclic AMP gradually increases following the three increasing infusion rates of ACTH whereas similar levels of plasma corticosterone concentrations are reached at steady state; therefore the saturation of the adrenal cortical secretion is due to a step ulterior to cyclic AMP formation in the steroidogenesis. After 30-min infusions, plasma corticosterone concentration reaches its maximal value following a rate of ACTH input which evokes only a 4-fold increase in adrenal cyclic AMP content; however, there is a 250-fold increase of adrenal cyclic AMP with respect to control value following the higher rates of infusion of ACTH.

Distribution and metabolism of adrenocorticotropin in the rat

The time course of plasma bioactive adrenocorticotropin (ACTH) concentrations measured following two rapid injections of the hormone at doses of 7.5 and 22.5 mU/100 g, iv, and one infusion over a period of 80 min at a rate of 1.3 mU/min per 100 g, to male Sprague-Dawley rats whose endogenous release of ACTH had been blocked, leads to the conclusion that the hormone is distributed in two compartments. Indeed, the rapid fall of plasma ACTH concentrations in the early minutes following either the injections or the stop of the infusion is followed by a much slower phase. There is no significant difference between the measurements and the two-compartment model outputs. The model represents, on the average, the mean values of the measurements plus or minus 1 standard error for the single injections and plus or minus 1.2 standard error for the infusion.

[Hospitalisation at home of children seen in a pediatric outpatients (author's transl)]

The authors relate their experience of hospitalisation at home of 74 children selected in a pediatric outpatients over a period of 5 years. They show the advantages of this method of care which are much greater than the few disadvantages and regret that it is not used more often.

[Catheterisation of the internal jugular vein for parenteral nutrition (author's transl)]

The technique consists of surgical exposure of the vein, its isolation by two threads and the introduction of a soft prethoracic exit. This technique avoids the complications inherent in any blind puncture of a large vessel. By virtue of the type of catheter (soft silicone) and the long subcutaneous course. It may be left in place for more than a month.

Metabolic clearance rate of adrenocorticotropin in the rat

The metabolic clearance rate (MCR) of adrenocorticotropin (ACTH) was estimated after the intravenous infusion of graded rates of the hormone (40-2560 muU/min per 100 g body weight) in rats pretreated with chlorpromazine, morphine, and Nembutal, a preparation which proved effective in blocking endogenous ACTH release. The hormone was infused over a period of 45 min, at which time the plasma ACTH concentration had reached a steady state. A specific and sensitive bioassay, based on the corticosterone production of dispersed adrenal cells, was used to measure the plasma ACTH concentration. With increasing infusion rates of ACTH, a threefold decrease in the MCR of ACTH was observed. Previous studies of our group have shown that the MCR of corticosterone increases as a function of the infusion rate of the steroid. It appears, therefore, that the metabolism of these two hormonal links of the hypothalamo-pituitary-adrenocortical axis vary in opposite fashions as a function of the secretion rate of the hormone.

[Adrenocortical responses to ACTH (author's transl)]

To characterize by a mathematical model the dynamics of adrenocortical responses to ACTH, the concentration of plasma corticosterone was measured following a series of injections and perfusions of ACTH to dexamethasone-treated male rats. A similar slope was observed during the rise of plasma corticosterone following graded pulse inputs, and the steady-state corticosterone secretion rate was shown to increase proportionally to the perfusion rate of ACTH up to saturation corresponding to maximal secretion. The data will be used, concurrently with our model of the dynamics of plasma cortiscosterone, for the identification of a mathematical model of the adrenocortical response to ACTH.

Relationship between ACTH release and corticosterone binding by the receptor sites of the adenohypophysis and dorsal hippocampus following infusion of corticosterone at a constant rate in the adrenalectomized rat

The amount of corticosterone bound to proteins in the adenohypophysis and dorsal hippocampus was studied concurrently with the plasma ACTH concentration in 4-week adrenalectomized male rats under steady-state conditions achieved by infusing the steroid at a constant rate for 45 min. Corticosterone binding was measured by gel chromatography on Sephadex LH-20, using a TE buffer containing 0.4 m NaCl. No saturation was observed in whole homogenates and supernatants with increasing plasma corticosterone concentrations. However, corticosterone binding by the pituitary and by one of two types of hippocampal receptors evidenced saturation within our range of corticosterone infusion rates, indeed. Scatchard plots allowed us to distinguish two types of binding sites in the hippocampus. The first, saturated at a low corticosterone concentration has an association constant of 3.0 times 10-8 M-1 with a number of binding sites estimated at 150 times 10- minus 15 mol/mg protein, whereas the second is associated with non-specific binding. The adenohypophysis shows only one kind of binding site with an association constant of 3.6 times 10-8 m- minus 1 and a number of sites estimated at 989 times 10- minus 15 mol/mg protein. A suggestive relationship was observed between ACTH inhibition by corticosterone and saturation of the pituitary binding sites. Our data are consistent with the possible involvement of corticosterone binding by specific sites in the negative feedback regulation of ACTH release.

Feedback inhibition of adrenocorticotropin release by corticosterone infusions in the adrenalectomized rat

Advantage was taken of a specific and sensitive bioassay for rat plasma adrenocorticotropin (ACTH) based on the dispersion of rat adrenal cells with trysin, to investigate the relationship between plasma corticosterone concentration and inhibition of ACTH release under steady-state conditions achieved by graded rates (0-5.12 mug/min per 100 g body weight) of intravenous infusion of the steroid for 45 min in 28-day adrenalectomized rats. In contrast to prior reports involving suppression of stress-induced ACTH release, the inhibitory effect of corticosterone was shown, under our experimental conditions, to be exerted also on the basal rate of ACTH secretion. Indeed, a slight though not significant decrease of plasma ACTH concentration was observed with the corticosterone infusion rate of 0.64 mg/min per 100 g body weight, and further progressive and highly significant drops in concentration were recorded for infusion rates of 2.56 and 5.12 mg/min per 100 g body weight. An increase of the metabolic clearance rate of corticosterone, observed as a function of the infusion rate, was ascribed to saturation by the steroid of the plasma transcortin binding sites.

APL computer program for the analytical and numerical integration of hormonal disappearance data

The biomedical applications of a new programming language characterized by simplicity and economy of symbols and coupled with access to remote terminals are illustrated by the description and analysis of a program pertaining to the lengthy computations involved in certain aspects of hormonal kinetics and their statistical correlates.

Numerical versus analytical integration of hormonal disappearance data

After a single rapid injection of a hormone, evaluation of the metabolic clearance rate (MCR) and of its error is greatly facilitated when a numerical technique, such as the trapezoidal rule, is substituted for regression as a means of determining the area under the disappearance curve, which is the only parameter needed to characterize overall metabolism. Integration is achieved by summing trapezes defined through successive data points and the corresponding time intervals. The error in the resulting area, which is derived from the propagation of the independent errors of the trapezes, is proportionately related to the MCR. This method, which is applicable to any dynamic pattern of disappearance, provides the only available means of computing a realistic error for the MCR of a hormone which is distributed into several compartments. The statistical advantages of the numerical approach over regression analysis are illustrated in connection with experimental data pertaining to the disappearance from plasma, in the adult male rat, of thyrotropic hormone and of corticosterone which are respectively distributed into one and three compartments.