Growth hormone nadir during oral glucose load depends on waist circumference, gender and age: normative data in 231 healthy subjects.

Objective  (i) To analyse the predictors of GH suppression after standard glucose load (oGTT) in the healthy population and (ii) to establish the 97th percentile of GH nadir post-oGTT according to these variables. Design  Analytical, retrospective. Measurements  GH nadir after oGTT. Subjects  Two hundred and thirty-one healthy subjects (113 women, 118 men 15-80 years) were studied. Results  The GH nadir after glucose load ranged from 0·01 (<assay detection limit) to 0·65 μg/l was higher in women and was inversely correlated with age, BMI, waist circumference, waist/hip, total cholesterol, triglycerides, basal and maximal glucose and basal insulin levels and directly correlated with basal GH levels, IGF-I SDS and HDL-cholesterol (P values ranging 0·004-<0·0001). On multistep regression analysis, the best predictors of nadir GH levels were waist circumference (t = -9·64, P < 0·0001), gender (t = -3·86, P = 0·0001) and age (t = -3·63, P = 0·0003). The results of comparative analysis among subjects grouped according to these variable showed different results in GH nadir in premenopausal women with waist circumference ≤88 cm (97th percentile 0·65 μg/l), in premenopausal women with waist circumference ≤88 cm and in men of any age with waist circumference ≤102 cm (97th percentile 0·33 μg/l) and in subjects of either gender and any age with waist circumference >88 cm in women and 102 cm in men (97th percentile 0·16 μg/l). Conclusions  The results of this study show that GH nadir after oGTT should be analysed according to gender, menopausal status and waist circumference. The GH cut-off should be limited to the assay used

Double-Differential Amplifier for sEMG Measurement by Means of a Current-Mode Approach

This work proposes a Double Differential (DD) amplifier topology which exploits the advantages of the current-mode approach. DD amplifiers are useful as front-ends in standalone active electrodes for superficial electromyography (sEMG) wearable applications and electroneurography (ENG) measurement devices. Front-ends for these applications need to attain low noise, high common-mode rejection ratio, and high input impedance to measure biopotential signals and can further benefit from low power operation, a small size, and an easily adaptable output. Presently published DD amplifiers are either complex in terms of a high part count, leading to higher power consumption and size, or suffer from limited interference-rejection capabilities and require further analog processing for compatibility with single-ended systems. Therefore, in this work, second-generation current conveyors have been leveraged to obtain a simple topology combining a small active-part count, a high common-mode rejection ratio, and a flexible output stage. The current-mode DD amplifier is presented and analyzed in detail to estimate its parameters and model the effects of nonidealities in the circuit. In order to validate the proposed topology, a discrete-component implementation was realized as a proof-of-concept. The results experimentally demonstrated the properties of the proposed topology and its feasibility for measuring superficial sEMG DD signals.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

A Memory-Targeted Dynamic Reconfigurable Charge Pump to Achieve a Power Consumption Reduction in IoT Nodes

Targeting the more recently adopted low-power memories for data-logging operation in IoT nodes, this paper presents a simple reconfigurable dual-branch cross-coupled charge pump (CP) topology in which clock amplitude scaling and modulation of the number of stages are exploited to improve power efficiency and/or change the output voltage without degrading speed performance. The proposed solution allows a reduction of the power conversion losses, maintaining speed, maximum output voltage and silicon area unaltered as compared to the conventional charge pump. Post-layout simulation results confirm the effectiveness of the proposed topology which can be adapted to any other kind of linear charge pump

A Subthreshold Cross-Coupled Hybrid Charge Pump for 50-mV Cold-Start

In this article, a fully-integrated switched-capacitor DC-DC converter based on a Dickson charge pump able to work with input voltage levels that force the transistors working in subthreshold region is presented. The proposed topology exploits resistors in the charge transfer switch in order to overcome the limits of conventional solutions when working in the subthreshold regime. Post-layout simulations using a 28-nm FD-SOI technology show that the CP can boost an input voltage as low as 50 mV to a maximum output voltage of 270 mV, keeping a settling time about 25X lower than the conventional dual-branch cross-coupled charge pump and a voltage conversion efficiency higher than 76%. The proposed topology is particularly suited for the start-up of power management units supplied by thermoelectric generators

A Methodology to Derive a Symbolic Transfer Function for Multistage Amplifiers

In this paper, a simple while effective methodology to calculate the symbolic transfer function of a multistage amplifier with frequency compensation is proposed. Three general amplifier models are introduced and analyzed, which represent basic topologies found in the literature. For these amplifier models, the symbolic transfer function is derived and specific strategies for the zero and non-dominant pole expressions are presented. The methodology is suited for hand calculations and yields accurate results while offering more intuition into the operation of the widely adopted frequency compensation solutions discussed in the literature. The effectiveness of the proposed approach is validated through various typical cases of study

Seismic Early Warning Systems: Procedure for Automated Decision Making

An Early Warning System potentially allows mitigation measures to be carried out from the moment in which a seismic event is detected. Examples of such measures are evacuation of buildings, shut-down of critical systems (nuclear reactors, industrial chemical processes, etc.) and stopping of high-speed trains. The type of mitigation measures that can be effectively activated depends on the amount of warning time available, but timeliness is often in conflict with the reliability of the predictions, which become more accurate as more seismic sensor data is collected. There is therefore an inevitable trade-off between the amount of warning time available and the reliability of the predictions provided by the Early Warning System. To investigate this trade-off, the consequences of the two alternatives of taking mitigation actions or not acting must be analyzed, accounting for significant uncertainty in the predictions. In this report, we present a decision-making procedure based on the real-time evaluation of the consequences of taking no action and of activating mitigation measures which is based on the probabilities of false and missed alerts. The threshold at which mitigating actions should be taken is quantified based on a cost-benefit analysis. The method is applied to two recent seismic events in Southern California, an M 4.75 event in Yorba Linda and an M 6.5 event in San Simeon. Also, a feasibility assessment of any proposed regional Early Warning System is of critical importance, and it should involve an examination of whether the requirements, in terms of warning time available and the probability of making wrong decisions, are met. A useful tool in this assessment of an Early Warning System is a seismic hazard map to provide the probability of exceedance of ground shaking intensity, given a site and time interval of interest, and a corresponding map of the probability of making a wrong decision. In this report, a methodology is presented for estimating the probabilities of making wrong decisions that can be incorporated in a feasibility assessment of proposed Early Warning System

Double-Differential Amplifier for sEMG Measurement by Means of a Current-Mode Approach

This work proposes a Double Differential (DD) amplifier topology which exploits the advantages of the current-mode approach. DD amplifiers are useful as front-ends in standalone active electrodes for superficial electromyography (sEMG) wearable applications and electroneurography (ENG) measurement devices. Front-ends for these applications need to attain low noise, high common-mode rejection ratio, and high input impedance to measure biopotential signals and can further benefit from low power operation, a small size, and an easily adaptable output. Presently published DD amplifiers are either complex in terms of a high part count, leading to higher power consumption and size, or suffer from limited interference-rejection capabilities and require further analog processing for compatibility with single-ended systems. Therefore, in this work, second-generation current conveyors have been leveraged to obtain a simple topology combining a small active-part count, a high common-mode rejection ratio, and a flexible output stage. The current-mode DD amplifier is presented and analyzed in detail to estimate its parameters and model the effects of nonidealities in the circuit. In order to validate the proposed topology, a discrete-component implementation was realized as a proof-of-concept. The results experimentally demonstrated the properties of the proposed topology and its feasibility for measuring superficial sEMG DD signals.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Comparison of the effects of primary somatostatin analogue therapy and pituitary adenomectomy on survival in patients with acromegaly: a retrospective cohort study

Objective: Acromegalic patients have an increased risk of mortality. The objective of this study was to compare the effect of different therapies for acromegaly on mortality. Design and methods: The mortality rate of 438 consecutive acromegalic patients was compared with that of the general population using the standardized mortality ratio (SMR); the effect of different therapies on survival was evaluated using Cox regression analysis. Results: Twenty patients (4.5%) died between 1999 and 2009. Age- and sex-adjusted SMR was 0.70 (95% CI 0.43–1.08). The Cox regression analysis revealed that, in the whole population, both general risk factors (age and physical status) and specific factors for acromegaly (macroadenoma, hypopituitarism and uncontrolled disease) were associated with death. The most compromised patients at diagnosis had a higher mortality rate (PZ0.001), which also occurred in patients with controlled acromegaly. Death occurred in 2.4% (adenomectomy), 2.6% (adenomectomy followed by somatostatin analogue (SSA) therapy) and 11.4% (SSA therapy as the primary therapy) of the patients. The risk of death was higher in patients receiving SSA therapy as the primary therapy (hazard ratio (HR) 5.52, 95% CI 1.06–28.77, PZ0.043) than in all patients submitted to adenomectomy; however, a higher risk of death occurred only in diabetic patients treated with SSAs alone (HR 21.94, 95% CI 1.56–309.04, PZ0.022). Radiotherapy was associated with an increased risk of mortality, which occurred in patients with the more locally advanced disease. Conclusions: Therapies for acromegaly and comorbidities have lowered the risk of mortality to the level of the general population; the effect of SSA therapy alone or that following pituitary adenomectomy was comparable to that of curative neurosurgery on survival in non-diabetic patients; on the contrary, SSA therapy as the primary therapy may be less effective than adenomectomy in reducing mortality rate in diabetic patients

Relapse of immune-mediated thrombotic thrombocytopenic purpura following mRNA COVID-19 vaccination: a prospective cohort study

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening disease. Vaccination has been reported to be a trigger of onset and relapse of autoimmune diseases. We evaluated after mRNA COVID-19 vaccination 32 adult patients previously diagnosed with iTTP by means of weekly monitoring of complete blood count and ADAMTS13 testing. Thirty of 32 patients received at least one dose of Pfizer-BioNTech, the remaining two received Moderna. A total of five patients, all vaccinated with Pfizer-BioNTech, had a biochemical relapse at a median post-vaccination time of 15 days following the second or third vaccine dose, presenting without measurable ADAMTS13 activity and a median anti- ADAMTS13 autoantibody value of 34 U/mL. Four of five cases had concomitant clinical relapse and were treated with corticosteroids alone or daily sessions of plasma exchange and caplacizumab, while one patient was closely monitored with ADAMTS13 with no onset of anemia and thrombocytopenia. Although the benefits of vaccination exceed its potential risks, clinicians should be aware that iTTP relapse might follow COVID-19 vaccination. Therefore, laboratory and clinical monitoring of iTTP patients should be done in the first post-vaccination month, in order to promptly diagnose and treat any relapse