Olivia Amoussou Guenou Honors Porfolio

Olivia Amoussou Guenou\u27s honors portfolio captured in May 2023

Adiponectin, in contrast to leptin, is not associated with body mass index, waist circumference and HOMA-IR in subjects of a west-African population

Factors associated with plasma levels of adiponectin and leptin were studied in adult subjects without diabetes from Cotonou in Benin (West‐Africa). Seventy (70) men and 45 women were included in the study. Anthropometric variables were measured and a venous blood sample was drawn from each subject, after an overnight fasting period, for measurement of plasma glucose, insulin, leptin, and adiponectin levels. HOMA‐IR was determined to assess insulin resistance. Adiponectin and leptin levels were higher in women than in men (with adiponectin 18.48 ± 12.77 vs.7.8 ± 10.39 μg/mL, P < 0.0001, and leptin 30.77 ± 19.16 vs. 8.66 ± 8.24 ng/mL, P < 0.0001). Fasting insulin level and HOMA‐IR were also higher in the females. Hyperleptinemia was observed in 66,96% of subjects and hypoadiponectinemia was present in 44.35% of subjects. In both men and women, leptin correlated with age (r = 0.2; P = 0.02), BMI (r = 0.572; P < 0.0001), waist circumference (r = 0.534; P < 0.0001), fasting insulin (r = 0.461; P < 0.001), and HOMA‐IR (r = 0.430; P < 0.0001). No significant correlation was observed for adiponectin levels with these variables. Only in women, adiponectin was inversely correlated with fasting glucose (r = −0.423; P < 0.004). These data confirm previous descriptions of leptin but suggest that variations in factors determining serum adiponectin levels observed between ethnicities could also been seen between populations from the same ethnicity

Correctness of Tendermint-Core Blockchains

Tendermint-core blockchains (e.g. Cosmos) are considered today one of the most viable alternatives for the highly energy consuming proof-of-work blockchains such as Bitcoin and Ethereum. Their particularity is that they aim at offering strong consistency (no forks) in an open system combining two ingredients (i) a set of validators that generate blocks via a variant of Practical Byzantine Fault Tolerant (PBFT) consensus protocol and (ii) a selection strategy that dynamically selects nodes to be validators for the next block via a proof-of-stake mechanism. The exact assumptions on the system model under which Tendermint underlying algorithms are correct and the exact properties Tendermint verifies, however, have never been formally analyzed. The contribution of this paper is as follows. First, while formalizing Tendermint algorithms we precisely characterize the system model and the exact problem solved by Tendermint, then, we prove that in eventual synchronous systems a modified version of Tendermint solves (i) under additional assumptions, a variant of one-shot consensus for the validation of one single block and (ii) a variant of the repeated consensus problem for multiple blocks. These results hold even if the set of validators is hit by Byzantine failures, provided that for each one-shot consensus instance less than one third of the validators is Byzantine

On Fairness in Committee-Based Blockchains

Committee-based blockchains are among the most popular alternatives of proof-of-work based blockchains, such as Bitcoin. They provide strong consistency (no fork) under classical assumptions, and avoid using energy-consuming mechanisms to add new blocks in the blockchain. For each block, these blockchains use a committee that executes Byzantine-fault tolerant distributed consensus to decide the next block they will add in the blockchain. Unlike Bitcoin, where there is only one creator per block, in committee-based blockchain any block is cooperatively created. In order to incentivize committee members to participate in the creation of new blocks, rewarding schemes have to be designed. In this paper, we study the fairness of rewarding in committee-based blockchains and we provide necessary and sufficient conditions on the system communication under which it is possible to have a fair reward mechanism

Modulation of immune cells and Th1/Th2 cytokines in insulin-treated type 2 diabetes mellitus.

Background: The role of the immune system in insulin resistance associated with type 2 diabetes has been suggested. Objectives: We assessed the profile of Th1/Th2 cytokines along with the frequencies of immune cells in insulin-treated type 2 diabetic patients (T2DP). Methods: 45 T2D patients and 43 age-matched healthy subjects were selected. Serum concentrations of T-helper type 1 (Th1) and Th2 cytokines and the frequencies of innate and adaptive immunity cells were assessed. Results: T2DP were hyperglycemic and showed high level of insulin, normal levels of triglycerides and total-cholesterol and without any change in HDL-cholesterol.Compared to healthy subjects, T2DP exhibited significant decreased frequencies of neutrophils, without any change in monocytes, eosinophils and natural killer cells. The percentages of total lymphocytes (CD3+) and CD8+-T-cells decreased whereas those of regulatory T-cells increased without any change in CD4+ T-cells in T2DP. Interestingly, the frequencies of effector CD4+-T and B-cells increased in T2DP. Serum concentrations of IL-2, IFN-\u3b3 and IL-4 decreased while IL-10 significantly enhanced in T2DP, suggesting a differentiation of CD4+T helper cells towards IL-10-producing- Teff-cells in these patients. Conclusion: Insulin-treated type 2 diabetes is associated with anti-inflammatory profile consistent with differentiation of CD4+-Th-cells towards IL-10-producing-Teff-cells, concomitant with increased frequencies of Treg and B-cells, and this may probably offer prevention against certain infections or autoimmune/inflammatory diseases

Adiponectin, in contrast to leptin, is not associated with body mass index, waist circumference and HOMA-IR in subjects of a west-African population

Factors associated with plasma levels of adiponectin and leptin were studied in adult subjects without diabetes from Cotonou in Benin (West‐Africa). Seventy (70) men and 45 women were included in the study. Anthropometric variables were measured and a venous blood sample was drawn from each subject, after an overnight fasting period, for measurement of plasma glucose, insulin, leptin, and adiponectin levels. HOMA‐IR was determined to assess insulin resistance. Adiponectin and leptin levels were higher in women than in men (with adiponectin 18.48 ± 12.77 vs.7.8 ± 10.39 μg/mL, P < 0.0001, and leptin 30.77 ± 19.16 vs. 8.66 ± 8.24 ng/mL, P < 0.0001). Fasting insulin level and HOMA‐IR were also higher in the females. Hyperleptinemia was observed in 66,96% of subjects and hypoadiponectinemia was present in 44.35% of subjects. In both men and women, leptin correlated with age (r = 0.2; P = 0.02), BMI (r = 0.572; P < 0.0001), waist circumference (r = 0.534; P < 0.0001), fasting insulin (r = 0.461; P < 0.001), and HOMA‐IR (r = 0.430; P < 0.0001). No significant correlation was observed for adiponectin levels with these variables. Only in women, adiponectin was inversely correlated with fasting glucose (r = −0.423; P < 0.004). These data confirm previous descriptions of leptin but suggest that variations in factors determining serum adiponectin levels observed between ethnicities could also been seen between populations from the same ethnicity

Consensus en Présence de Participants Rationnels et Byzantins

International audienceNous étudions les comportements des participants d'un protocole de consensus lorsqu'ils présentent des comportements rationnels ou Byzantins. Nous nous inspirons des protocoles de blockchains tolérantes aux fautes Byzantines (comme Tendermint). Dans ces protocoles, les participants proposent des blocs et s'échangent des messages. Un bloc est accepté si une majorité de participants envoie le message correspondant à ce bloc (un vote), et les votants sont récompensés. Dans ce travail, nous étudions les conditions sous lesquelles ce protocole satisfait les deux propriétés suivantes : la terminaison (le système converge vers une décision) et la validité (toute décision est valide), quand certains participants sont rationnels et les autres Byzantins. Nous supposons que les participants Byzantins ont le comportement infligeant le plus de dégâts au système, tandis que les stratégies des participants rationnels forment un équilibre Bayésien parfait. Nous considérons les paramètres suivant : (i) le nombre de votes nécessaires, ν, pour qu'un bloc soit considéré comme accepté, et (ii) le nombre de participants Byzantins, noté f , dans le système. Nous obtenons les résultats suivants : Quand f ≥ ν, les blocs invalides sont acceptés, et donc la validité ne peut être garantie ; Quand f < ν, il existe un équilibre où la validité et la terminaison sont toutes deux satisfaites, par contre, il existe d'autres équilibres où la terminaison, et dans quelques cas la validité, ne sont pas satisfaites. Cela nous permet de conclure à l'existence de problèmes de coordination dans les protocoles étudiés

Blockchains basées sur du Consensus Répété

International audienceLes blockchains basées sur le consensus sont considérées aujourd'hui comme étant parmi les alternatives les plus viables aux blockchains utilisant un mécanisme de Proof-of-work (Bitcoin, Ethereum,. . .), ces dernières étant très énergivores et ne garantissent pas une cohérence forte. Elles ont pour but d'offrir des garanties de cohérence forte (pas de fourches) dans un système ouvert grâce à : (i) un ensemble de validateurs qui produit un bloc via une variante du protocole de consensus Practical Byzantine Fault Tolerant (PBFT), et (ii) un mécanisme de sélection qui choisit dynamiquement les noeuds qui seront validateurs pour le bloc suivant. Dans cet article, nous caractérisons précisément le problème que tentent de résoudre ces protocoles de blockchains. Nous étudions Tendermint. Nos contributions sont les suivantes : nous formalisons pour la première fois le protocole Tendermint, puis nous présentons le modèle et les hypothèses précis sous lesquels il atteint son objectif. Nous prouvons que dans un système ultimement synchrone et avec une hypothèse supplémentaire, une légère modification du protocole résout une variante (i) du consensus pour la production d'un bloc, et une variante (ii) du consensus répété pour construire la chaîne de bloc ; cela si strictement moins d'un tiers des validateurs est atteint de fautes Byzantines. Nous nous sommes ensuite intéressés à l'étude de l'équité du mécanisme de récompense dans ces blockchains. Cette étude préliminaire permet d'établir que garantir (ultimement) l'équité de la récompense requiert une communication (ultimement) synchrone

GAD65 antibody prevalence and association with c-peptide, HLA class II alleles in Beninese patients with type 1 diabetes

Background: Antibodies to glutamic acid decarboxylase and particularly their isoforms in 65 kDa are one of markers for the diagnosis of the type 1 diabetes (T1D). The aim of this study is to assess the prevalence of GAD65 antibodies (GAD65Ab) and investigate the association of GAD65Ab with C-peptide values, HLA Class II alleles genotyping. The diagnosis of T1D was set up according to American Diabetes Association criteria.Methods: Radioimmunoassay was used to determine the GAD65Ab and C-peptide values. Class II HLA genotyping was performed in 51 patients with T1D and 51 healthy unrelated as control by using the PCR-SSP method. The sensitivity and specificity of the tests were calculated by standard formula.Results: Result revealed that GAD65Ab were present in 74.5% (38/51) of the patients with T1D. There was no significant difference between the positivity or the negativity of GAD65Ab and gender, onset and duration of diabetes, frequencies of HLA-DR4, HLA-DR3-DR4, HLA-DQB1*0201. However, GAD65Ab values are linked to C-peptide concentration (χ2 =15.73, P=0.0001), the presence of HLA-DR3 (χ2 =9.75, P= 0.002), HLA-DQA1*0501 (χ2 =4.09, P= 0.043) alleles. The GAD65Ab test sensitivity and specificity were 74.5% and 94.1%, respectively. The C-peptide test showed a sensitivity around 82.4 % and 86.3 % for the specificity.Conclusions: GAD65Ab showed to be a valuable early predictive marker and is associated with the risk to develop of T1D

Rational Behavior in Committee-Based Blockchains

We study the rational behaviors of participants in committee-based blockchains. Committee-based blockchains rely on specific blockchain consensus that must be guaranteed in presence of rational participants. We consider a simplified blockchain consensus algorithm based on existing or proposed committee-based blockchains that encapsulates the main actions of the participants: voting for a block, and checking its validity. Knowing that those actions have costs, and achieving the consensus gives rewards to committee members, we study using game theory how strategic players behave while trying to maximizing their gains. We consider different reward schemes, and found that in each setting, there exist equilibria where blockchain consensus is guaranteed; in some settings however, there can be coordination failures hindering consensus. Moreover, we study equilibria with trembling participants, which is a novelty in the context of committee-based blockchains. Trembling participants are rational that can do unintended actions with a low probability. We found that in presence of trembling participants, there exist equilibria where blockchain consensus is guaranteed; however, when only voters are rewarded, there also exist equilibria where validity can be violated