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Background: Surveillance of influenza-like illness (ILI) in Central Africa began only recently, and few data are therefore available on the circulation of influenza virus and other respiratory viruses. In Gabon, a Central African country, we established a surveillance network in four major towns in order to analyze cases of ILI among patients who visited health centers between March 2010 and June 2011, and to determine the viral etiology. Methods: Nasal swabs were sent for analysis to the Centre International de Recherches Médicales de Franceville, where they were screened for 17 respiratory viruses in a multiplex real-time reverse transcription polymerase chain reaction for all pathogens according the following pairs: adenovirus/parainfluenza virus 4, respiratory syncytial virus/human metapneumovirus, parainfluenza virus 1/parainfluenza virus 2, pandemic influenza virus A/seasonal influenza virus A (H1N1, H3N2)/seasonal influenza virus B, human coronaviruses 229E/OC43, human coronaviruses NL63/ HKU1, rhinovirus/human parechovirus, and enterovirus/parainfluenza virus 3. Results: We analyzed a total of 1041 specimens, of which 639 (61%) were positive for at least one virus. Three-quarters of the patients were children under five years old. We therefore focused on this age group, in which 68.1% of patients were positive for at least one virus. The most common viruses were adenoviruses (17.5%), followed by parainfluenza viruses (PIVs) 1–4 (16.8%), enteroviruses (EV) (14.7%), respiratory syncytial virus (RSV) (13.5%), and influenza virus (11.9%). The prevalence of some viruses was subject to geographic and seasonal variations. One-third of positive samples contained more than one virus. Conclusions: Like most studies in the world, the virus PIVs, EV, RSV, Influenza virus, HRV were predominant among children under five years old in Gabon. An exception is made for adenoviruses which have a high prevalence in our study. However adenoviruses can be detected in asymptomatic persons. These finding gave a better knowledge of the circulation and the seasonality of the viruses involved in ILI in Gabon. [ABSTRACT FROM AUTHOR]

Nanoengineering Palladium Plasmonic Nanosheets Inside Polymer Nanospheres for Photothermal Therapy and Targeted Drug Delivery (Adv. Funct. Bupivacaine drug delivery, hybrid nanospheres, photothermal therapy, pickering double emulsion, plasmonic palladium Keywords: bupivacaine drug delivery; hybrid nanospheres; photothermal therapy; pickering double emulsion; plasmonic palladium EN bupivacaine drug delivery hybrid nanospheres photothermal therapy pickering double emulsion plasmonic palladium 1 1 1 02/24/22 20220223 NES 220223 B Photothermal Therapy b In article number 2106932, Manuel Arruebo, Victor Sebastian, and co-workers demonstrate a facile and effective procedure to assemble near-infrared-sensitive Pd nanosheets into a drug-loaded biopolymeric nanoparticle, resulting in an efficient theragnostic vector. [Extracted from the article]

We tested 144 pet rabbits sampled in France between November 2020 and June 2021 for antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by microsphere immunoassay. We reported the first evidence of a natural SARS-CoV-2 infection in rabbits with a low observed seroprevalence between 0.7% and 1.4%. [ABSTRACT FROM AUTHOR]

The task of international expert groups is to recommend the classification and naming of viruses. The International Committee on Taxonomy of Viruses Filoviridae Study Group and other experts have recently established an almost consistent classification and nomenclature for filoviruses. Here, further guidelines are suggested to include their natural genetic variants. First, this term is defined. Second, a template for full-length virus names (such as 'Ebola virus H.sapiens-tc/COD/1995/Kikwit-9510621') is proposed. These names contain information on the identity of the virus (e.g., Ebola virus), isolation host (e.g., members of the species Homo sapiens), sampling location (e.g., Democratic Republic of the Congo (COD)), sampling year, genetic variant (e.g., Kikwit), and isolate (e.g., 9510621). Suffixes are proposed for individual names that clarify whether a given genetic variant has been characterized based on passage zero material (-wt), has been passaged in tissue/cell culture (-tc), is known from consensus sequence fragments only (-frag), or does (most likely) not exist anymore (-hist). We suggest that these comprehensive names are to be used specifically in the methods section of publications. Suitable abbreviations, also proposed here, could then be used throughout the text, while the full names could be used again in phylograms, tables, or figures if the contained information aids the interpretation of presented data. The proposed system is very similar to the well-known influenzavirus nomenclature and the nomenclature recently proposed for rotaviruses. If applied consistently, it would considerably simplify retrieval of sequence data from electronic databases and be a first important step toward a viral genome annotation standard as sought by the National Center for Biotechnology Information (NCBI). Furthermore, adoption of this nomenclature would increase the general understanding of filovirus-related publications and presentations and improve figures such as phylograms, alignments, and diagrams. Most importantly, it would counter the increasing confusion in genetic variant naming due to the identification of ever more sequences through technological breakthroughs in high-throughput sequencing and environmental sampling. [ABSTRACT FROM AUTHOR]

Ebolavirus and Marburgvirus, two filoviruses belonging to the Filoviridae family, are among the most virulent pathogens for humans and non-human primates, causing outbreaks of fulminant hemorrhagic fever (HF) in Central African countries with case fatality rates of up to 90%. Fruit bats are the likely reservoir, and human infection occurs through contact with bats or infected large-animal carcasses or by person-to-person contact (through body fluids, medical care, and burial practices). Schematically, clinical manifestations occur in three successive phases and include general, gastrointestinal, and mucocutaneous disorders. Death usually results from hemorrhagic complications. Cutaneous manifestations rarely make a major contribution to disease severity but can assist with the diagnosis. Rash, the main cutaneous disorder, is nonspecific and cannot guide the differential diagnosis. Immunohistochemical examination of skin biopsy or necropsy specimens can confirm the diagnosis. [ABSTRACT FROM AUTHOR]

Background: Human retroviral infections such as Human Immunodeficiency Virus (HIV) or Human T-cell Lymphotropic Virus (HTLV) are the result of simian zoonotic transmissions through handling and butchering of Non-Human Primates (NHP) or by close contact with pet animals. Recent studies on retroviral infections in NHP bushmeat allowed for the identification of numerous Simian Immunodeficiency Viruses (SIV) and Simian T-cell Lymphotropic Viruses (STLV) to which humans are exposed. Nevertheless, today, data on simian retroviruses at the primate/hunter interface remain scarce. We conducted a pilot study on 63 blood and/or tissues samples derived from NHP bushmeat seized by the competent authorities in different locations across the country. Results: SIV and STLV were detected by antibodies to HIV and HTLV antigens, and PCRs were performed on samples with an HIV or/and HTLV-like or indeterminate profile. Fourteen percent of the samples cross-reacted with HIV antigens and 44% with HTLV antigens. We reported STLV-1 infections in five of the seven species tested. STLV-3 infections, including a new STLV-3 subtype, STLV-1 and -3 co-infections, and triple SIV, STLV-1, STLV-3 infections were observed in red-capped mangabeys (C.torquatus). We confirmed SIV infections by PCR and sequence analyses in mandrills, red-capped mangabeys and showed that mustached monkeys in Gabon are infected with a new SIV strain basal to the SIVgsn/mus/mon lineage that did not fall into the previously described SIVmus lineages reported from the corresponding species in Cameroon. The same monkey (sub)species can thus be carrier of, at least, three distinct SIVs. Overall, the minimal prevalence observed for both STLV and SIV natural infections were 26.9% and 11.1% respectively. Conclusions: Overall, these data, obtained from a restricted sampling, highlight the need for further studies on simian retroviruses in sub-Saharan Africa to better understand their evolutionary history and to document SIV strains to which humans are exposed. We also show that within one species, a high genetic diversity may exist for SIVs and STLVs and observe a high genetic diversity in the SIVgsn/mon/mus lineage, ancestor of HIV-1/SIVcpz/SIVgor. [ABSTRACT FROM AUTHOR]

Background. Zaire ebolavirus was responsible for 2 outbreaks in Democratic Republic of the Congo (DRC), in 1976 and 1995. The virus reemerged in DRC 12 years later, causing 2 successive outbreaks in the Luebo region, Kasai Occidental province, in 2007 and 2008. Methods. Viruses of each outbreak were isolated and the full-length genomes were characterized. Phylogenetic analysis was then undertaken to characterize the relationships with previously described viruses. Results. The 2 Luebo viruses are nearly identical but are not related to lineage A viruses known in DRC or to descendants of the lineage B viruses encountered in the Gabon-Republic of the Congo area, with which they do, however, share a common ancestor. Conclusions. Our findings strongly suggest that the Luebo 2007 outbreak did not result from viral spread from previously identified foci but from an independent viral emergence. The previously identified epidemiological link with migratory bat species known to carry Zaire ebolavirus RNA support the hypothesis of viral spillover from this widely dispersed reservoir. The high level of similarity between the Luebo2007 and Luebo2008 viruses suggests that local wildlife populations (most likely bats) became infected and allowed local viral persistence and reemergence from year to year. [ABSTRACT FROM AUTHOR]

Background. In Gabon, several Ebolavirus outbreaks have occurred exclusively in the northeastern region. We conducted a large serosurvey to identify areas and populations at risk and potential demographic, clinical, and behavioral risk factors. Methods. Blood samples and clinical and sociodemographic data were collected from 4349 adults and 362 children in a random sample of 220 villages in the 9 provinces of Gabon. An enzyme-linked immunosorbent assay was used to detect Zaire ebolavirus (ZEBOV)-specific IgG, and thin blood smears were used to detect parasites. Logistic regression was implemented using Stata software (Stata), and a probability level of <.05 was considered to be statistically significant. Results. The prevalence of ZEBOV-specific IgG was 15.3% overall, increasing to 32.4% (P< .001) in forest areas. No sociodemographic risk factors were found, but the antibody prevalence increased linearly up to 20 years of age. Chronic arthralgia and amicrofilaremia were the only factors associated with ZEBOV seropositivity. Conclusions. These findings confirm the endemicity of ZEBOV in Gabon and its link to the ecosystem. Human antibody positivity would appear to be to the result of exposure to contaminated fruits. [ABSTRACT FROM AUTHOR]

Background: Rapidly spreading to new regions, including the islands of the Indian Ocean, Central Africa, and Europe, Chikungunya fever is becoming a major problem of public health. Unlike other members of the alphavirus genus, immune responses to Chikungunya virus (CHIKV) have been poorly investigated.Methods: We conducted a large ex vivo multiplex study of 50 cytokine, chemokine, and growth factor plasma profiles in 69 acutely infected patients from the Gabonese outbreak of 2007. We also assessed a phenotypic study of T lymphocyte responses during human acute CHIKV infection.Results: CHIKV infection in humans elicited strong innate immunity involving the production of numerous proinflammatory mediators. Interestingly, high levels of Interferon (IFN) α were consistently found. Production of interleukin (IL) 4, IL-10, and IFN-γ suggested the engagement of the adaptive immunity. This was confirmed by flow cytometry of circulating T lymphocytes that showed a CD8+ T lymphocyte response in the early stages of the disease, and a CD4+ T lymphocyte mediated response in the later stages. For the first time to our knowledge, we found evidence of CD95-mediated apoptosis of CD4+ T lymphocytes during the first 2 days after symptoms onset, ex vivo.Conclusions: Together, our findings suggest that strong innate immunity is required to control CHIKV infection. [ABSTRACT FROM AUTHOR]

Plasmodium reichenowi, a chimpanzee parasite, was until very recently the only known close relative of Plasmodium falciparum, the most virulent agent of human malaria. Recently, Plasmodium gaboni, another closely related chimpanzee parasite, was discovered, suggesting that the diversity of Plasmodium circulating in great apes in Africa might have been underestimated. It was also recently shown that P. reichenowi is a geographically widespread and genetically diverse chimpanzee parasite and that the world diversity of P. falciparum is fully included within the much broader genetic diversity of P. reichenowi. The evidence indicates that all extant populations of P. falciparum originated from P. reichenowi, likely by a single transfer from chimpanzees. In this work, we have studied the diversity of Plasmodium species infecting chimpanzees and gorillas in Central Africa (Cameroon and Gabon) from both wild-living and captive animals. The studies in wild apes used noninvasive sampling methods. We confirm the presence of P. reichenowi and P. gaboni in wild chimpanzees. Moreover, our results reveal the existence of an unexpected genetic diversity of Plasmodium lineages circulating in gorillas. We show that gorillas are naturally infected by two related lineages of parasites that have not been described previously, herein referred to as Plasmodium GorA and P. GorB, but also by P. falciparum, a species previously considered as strictly human specific. The continuously increasing contacts between humans and primate populations raise concerns about further reciprocal host transfers of these pathogens. [ABSTRACT FROM AUTHOR]

A method for image analysis was implemented to determine the edge pixels of two biopolymer-based thermoplastic filaments during their hot melt isothermal sintering at 120 °C. Successive inverted ellipses are adjusted to the contour of the sintered filaments and lead to the identification of the parameters of the corresponding lemniscates of Booth. The different steps of the morphological image analysis are detailed, from 8-bit coded acquired images (1 frame/s), to the final fitting of the optimized mathematical functions describing the evolution of the filaments envelope. The complete sequence is composed of an initial pure viscous sintering step during the first minute, followed by viscoelastic swelling combined with melt spreading for a longer time, and then the stabilization of the sintered filaments shape for over 2 min at high temperatures. Using a master curve obtained from Hopper's abacus, the characteristic viscous sintering time is assessed at tvs = 78 s, confirming the one previously found based on the measurement of the bonding neck length alone. Then, the full description of the evolution of the thermoplastic filaments envelope is assessable by image analysis during sintering trials as a result of its digital modeling as successive lemniscates of Booth, reflecting geometry changes in the molten state. [ABSTRACT FROM AUTHOR]

Background: Domestic pets can contract severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection; however, it is unknown whether the UK B.1.1.7 variant can more easily infect certain animal species or increase the possibility of human‐to‐animal transmission. Methods: This is a descriptive case series reporting SARS‐CoV‐2 B.1.1.7 variant infections in a group of dogs and cats with suspected myocarditis. Results: The study describes the infection of domestic cats and dogs by the B.1.1.7 variant. Two cats and one dog were positive to SARS‐CoV‐2 PCR on rectal swab, and two cats and one dog were found to have SARS‐CoV‐2 antibodies 2–6 weeks after they developed signs of cardiac disease. Many owners of these pets had developed respiratory symptoms 3–6 weeks before their pets became ill and had also tested positive for COVID‐19. Interestingly, all these pets were referred for acute onset of cardiac disease, including severe myocardial disorders of suspected inflammatory origin but without primary respiratory signs. Conclusions: These findings demonstrate, for the first time, the ability for pets to be infected by the B.1.1.7 variant and question its possible pathogenicity in these animals. [ABSTRACT FROM AUTHOR]

Canine monocytic ehlichiosis (CME), an enzootic disease in Africa, has been studied in canine blood samples (serum). These dogs, without any clinical sign of disease, were living in Abidjan (Ivory Coast) and in several small villages located in northeasst Gabon (Ogooué Ivindo). The results obtained by indirect fluorescent antibody (IFA) test, used as a point of reference, and by a quick test dot-Elisa were compared. Blood samples taken from 390 asymptomatic dogs in 2003 (137 in Ivory Coast and 253 in Gabon) were screened by IFA (antigen from Symbiotics Europe, Lyon) with a positive threshold set at 1/80. Afterwards, CME was detected by the commercial test kit Dot-Elisa in solid phase Snap 3Dx (Idexx, Westbrook, Maine, USA), using recombinant proteins which belong to Ehrlichia canis, p30 and p30-1. Using the IFA test, CME seroprevalence in the Ivory Coast is found to be 67.8%. Among 93 Ivorian seropositive blood samples, 76 samples show an antibody titer >1/2560. In Gabon, IFA showed that seroprevalence is only 3.1%. Among 8 seropositive Gabonese dogs, only one sample shows an antibody test titer> 1/2560. Results from the Snap 3Dx test used on 390 blood samples are 100 positive samples and 290 negative ones. Comparison between IFA and Snap test 3DX revealed that the Snap test shows 97.9% specificity, 93.1% sensitivity, a 94% positive predictive value, a 97.6%, negative predictive value, and 96.6% reliability. In conclusion, CME seroprevalence in Abidjan is very high. Dogs studied for CME were watchdogs, living in kennels, where infection transmitted by Rhipicephalus sanguineus seems to be higher in the Gabonese area called Ogooué Ivindo, where semi-stray dogs were subjected to the test. These dogs where carried ticks identified as Haemaphysalis leachi, but this kind of tick is not considered as bearing Ehrlichia canis. Finally, results of the Snap 3Dx show that it is a simple and reliablemeans for quickly detecting dogs suspected of asymptomatic canine ehrlichiosis. [ABSTRACT FROM AUTHOR]

During the period of December 2004 to January 2005, Bacillus anthracis killed three wild chimpanzees (Pan troglodytes troglodytes) and one gorilla (Gorilla gorilla gorilla) in a tropical forest in Cameroon. While this is the second anthrax outbreak in wild chimpanzees, this is the first case of anthrax in gorillas ever reported. The number of great apes in Central Africa is dramatically declining and the populations are seriously threatened by diseases, mainly Ebola. Nevertheless, a considerable number of deaths cannot be attributed to Ebola virus and remained unexplained. Our results show that diseases other than Ebola may also threaten wild great apes, and indicate that the role of anthrax in great ape mortality may have been underestimated. These results suggest that risk identification, assessment, and management for the survival of the last great apes should be performed with an open mind, since various pathogens with distinct characteristics in epidemiology and pathogenicity may impact the populations. An animal mortality monitoring network covering the entire African tropical forest, with the dual aims of preventing both great ape extinction and human disease outbreaks, will create necessary baseline data for such risk assessments and management plans. Am. J. Primatol. 68:928–933, 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Background. Patients who have refused to provide blood samples has meant that there have been significant delays in confirming outbreaks of Ebola virus hemorrhagic fever (EVHF). During the 2 EVHF outbreaks in the Republic of Congo in 2003, we assessed the use of oral fluid specimens versus serum samples for laboratory confirmation of cases of EVHF. Methods. Serum and oral fluid specimens were obtained from 24 patients with suspected Ebola and 10 healthy control subjects. Specimens were analyzed for immunoglobulin G antibodies by enzyme-linked immunosorbent assay (ELISA) and for Ebola virus by antigen detection ELISA and reverse-transcriptase polymerase chain reaction (RT-PCR). Oral fluid specimens were collected with a commercially available collection device. Results. We failed to detect antibodies against Ebola in the oral fluid specimens obtained from patients whose serum samples were seropositive. All patients with positive serum RT-PCR results also had positive results for their oral fluid specimens. Conclusions. This study demonstrates the usefulness of oral fluid samples for the investigation of Ebola outbreaks, but further development in antibodies and antigen detection in oral fluid specimens is needed before these samples are used for filovirus surveillance activities in Africa. [ABSTRACT FROM AUTHOR]

Abstract: The evolution of the coefficient of thermal expansion (CTE) of a thermosetting polymer during cure reaction is an important parameter for industrial applications such as composite processing since it influences the development of internal stresses in the material. The CTE being almost impossible to measure on a reacting thermoset, we propose to use an indirect method based on the modelling of ionic conductivity by a modified WLF equation, allowing to calculate the evolution of CTE from dielectric spectroscopy measurements. This method is applied to a dicyanate ester thermosetting polymer, leading to encouraging results both qualitatively and quantitatively. [Copyright &y& Elsevier]

During the 2001-2002 outbreak in Gabon, we observed that several dogs were highly exposed to Ebola virus by eating infected dead animals. To examine whether these animals became infected with Ebola virus, we sampled 439 dogs and screened them by Ebola virus-specific immunoglobulin (Ig) G assay, antigen detection, and viral polymerase chain reaction amplification. Seven (8.9%) of 79 samples from the 2 main towns, 15 (15.2%) of 99 samples from Mekambo, and 40 (25.2%) of 159 samples from villages in the Ebola virus-epidemic area had detectable Ebola virus-IgG, compared to only 2 (2%) of 102 samples from France. Among dogs from villages with both infected animal carcasses and human cases, seroprevalence was 31.8%. A significant positive direct association existed between seroprevalence and the distances to the Ebola virus-epidemic area. This study suggests that dogs can be infected by Ebola virus and that the putative infection is asymptomatic. [ABSTRACT FROM AUTHOR]

All human Ebola virus outbreaks during 2001-2003 in the forest zone between Gabon and Republic of Congo resulted from handling infected wild animal carcasses. After the first outbreak, we created an Animal Mortality Monitoring Network in collaboration with the Gabonese and Congolese Ministries of Forestry and Environment and wildlife organizations (Wildlife Conservation Society and Programme de Conservation et Utilisation Rationnelle des Ecosystemes Forestiers en Afrique Centrale) to predict and possibly prevent human Ebola outbreaks. Since August 2001, 98 wild animal carcasses have been recovered by the network, including 65 great apes. Analysis of 21 carcasses found that 10 gorillas, 3 chimpanzees, and 1 duiker tested positive for Ebola virus. Wild animal outbreaks began before each of the 5 human Ebola outbreaks. Twice we alerted the health authorities to an imminent risk for human outbreaks, weeks before they occurred. [ABSTRACT FROM AUTHOR]

The "switch-off" hypothesis to explain beta-cell regulation of alpha-cell function during hypoglycemia has not been assessed previously in isolated islets, largely because they characteristically do not respond to glucose deprivation by secreting glucagon. We examined this hypothesis using normal human and Wistar rat islets, as well as islets from streptozotocin (STZ)-administered beta-cell-deficient Wistar rats. As expected, islets perifused with glucose and 3-isobutryl-1-methylxanthine did not respond to glucose deprivation by increasing glucagon secretion. However, if normal rat islets were first perifused with 16.7 mmol/l glucose to increase endogenous insulin secretion, followed by discontinuation of the glucose perifusate, a glucagon response to glucose deprivation was observed (peak change within 10 min after switch off = 61 +/- 15 pg/ml [mean +/- SE], n = 6, P < 0.01). A glucagon response from normal human islets using the same experimental design was also observed. A glucagon response (peak change within 7 min after switch off = 31 +/- 1 pg/ml, n = 3, P < 0.01) was observed from beta-cell-depleted, STZ-induced diabetic rats whose islets still secreted small amounts of insulin. However, when these islets were first perifused with both exogenous insulin and 16.7 mmol/l glucose, followed by switching off both the insulin and glucose perifusate, a significantly larger (P < 0.05) glucagon response was observed (peak change within 7 min after switch off = 71 +/- 11 pg/ml, n = 4, P < 0.01). This response was not observed if the insulin perifusion was not switched off when the islets were deprived of glucose or when insulin was switched off without glucose deprivation. These data uniquely demonstrate that both normal, isolated islets and islets from STZ-administered rats can respond to glucose deprivation by releasing glucagon if they are first provided with increased endogenous or exogenous insulin. These results fully support the beta-cell switch-off hypothesis as a key mechanism for the alpha-cell response to hypoglycemia. [ABSTRACT FROM AUTHOR]

The glucagon response is the first line of defense against hypoglycemia and is lost in insulin-dependent diabetes. The beta-cell "switch-off" hypothesis proposes that a sudden cessation of insulin secretion from beta-cells into the portal circulation of the islet during hypoglycemia is a necessary signal for the glucagon response from downstream alpha-cells. Although indirect evidence exists to support this hypothesis, it has not been directly tested in vivo by provision and then discontinuation of regional reinsulinization of alpha-cells at the time of a hypoglycemic challenge. We studied streptozotocin (STZ)-induced diabetic Wistar rats that had no glucagon response to a hypoglycemic challenge. We reestablished insulin regulation of the alpha-cell by regionally infusing insulin (0.025 microU/min) directly into the superior pancreaticoduodenal artery (SPDa) of STZ-administered rats at an infusion rate that did not alter systemic venous glucose levels. SPDa insulin infusion was switched off simultaneously when blood glucose fell to <60 mg/dl after a jugular venous insulin injection. This maneuver restored the glucagon response to hypoglycemia (peak change within 5-10 min = 326 +/- 98 pg/ml, P < 0.05; and peak change within 15-20 min = 564 +/- 148 pg/ml, P < 0.01). No response was observed when the SPDa insulin infusion was not turned off (peak change within 5-10 min = 44 +/- 85 pg/ml, P = NS; and peak change within 15-20 min = 67 +/- 97 pg/ml, P = NS) or when saline instead of insulin was infused and then switched off (peak change within 5-10 min = -44 +/- 108 pg/ml, P = NS; and peak change within 15-20 min = -13 +/- 43 pg/ml, P = NS). No responses were observed during euglycemia (peak change within 5-10 min = 48 +/- 35 pg/ml, P = NS; and peak change within 15-20 min = 259 +/- 129 pg/ml, P = NS) or hyperglycemia (peak change within 5-10 min = 49 +/- 62 pg/ml, P = NS; and peak change within 15-20 min = 138 +/- 87 pg/ml, P = NS). Thus, the glucagon response to hypoglycemia that was absent in rats made diabetic by STZ was restored by regional infusion and then discontinuation of insulin. These data provide direct in vivo support for the beta-cell "switch-off" hypothesis and indicate that the alpha-cell is not intrinsically abnormal in insulin-dependent diabetes because of STZ-induced destruction of beta-cells. [ABSTRACT FROM AUTHOR]

The glucagon response is the first line of defense against hypoglycemia and is lost in insulin-dependent diabetes. The β-cell "switch-off" hypothesis proposes that a sudden cessation of insulin secretion from β-cells into the portal circulation of the islet during hypoglycemia is a necessary signal for the glucagon response from downstream α-cells. Although indirect evidence exists to support this hypothesis, it has not been directly tested in vivo by provision and then discontinuation of regional reinsulinization of α-cells at the time of a hypoglycemic challenge. We studied streptozotocin (STZ)-induced diabetic Wistar rats that had no glucagon response to a hypoglycemic challenge. We reestablished insulin regulation of the α-cell by regionally infusing insulin (0.025 µU/min) directly into the superior pancreaticoduodenal artery (SPDa) of STZ-administered rats at an infusion rate that did not alter systemic venous glucose levels. SPDa insulin infusion was switched off simultaneously when blood glucose fell to <60 mg/dl after a jugular venous insulin injection. This maneuver restored the glucagon response to hypoglycemia (peak change within 5-10 min = 326 ± 98 pg/ml, P < 0.05; and peak change within 15-20 min = 564 ± 148 pg/ml, P < 0.01). No response was observed when the SPDa insulin infusion was not turned off (peak change within 5-10 min = 44 ± 85 pg/ml, P = NS; and peak change within 15-20 min = 67 ± 97 pg/ml, P = NS) or when saline instead of insulin was infused and then switched off (peak change within 5-10 min = -44 ± 108 pg/ml, P = NS; and peak change within 15-20 min = -13 ± 43 pg/ml, P = NS). No responses were observed during euglycemia (peak change within 5-10 min = 48 ± 35 pg/ml, P = NS; and peak change within 15-20 min = 259 ± 129 pg/ml, P = NS) or hyperglycemia (peak change within 5-10 min = 49 ± 62 pg/ml, P = NS; and peak change within 15-20 min = 138 ± 87 pg/ml, P = NS). Thus, the glucagon response to hypoglycemia that was absent in rats made diabetic by STZ was restored by regional infusion and then discontinuation of insulin. These data provide direct in vivo support for the β-cell "switch-off" hypothesis and indicate that the α-cell is not intrinsically abnormal in insulin-dependent diabetes because of STZ-induced destruction of β-cells. [ABSTRACT FROM AUTHOR]

The "switch-off" hypothesis to explain β-cell regulation of α-cell function during hypoglycemia has not been assessed previously in isolated islets, largely because they characteristically do not respond to glucose deprivation by secreting glucagon. We examined this hypothesis using normal human and Wistar rat islets, as well as islets from streptozotocin (STZ)-administered β-celldeficient Wistar rats. As expected, islets perifused with glucose and 3-isobutryl-1-methylxanthine did not respond to glucose deprivation by increasing glucagon secretion. However, if normal rat islets were first perifused with 16.7 mmol/l glucose to increase endogenous insulin secretion, followed by discontinuation of the glucose perifusate, a glucagon response to glucose deprivation was observed (peak change within 10 min after switch off = 61 ± 15 pg/ml [mean ± SE], n = 6, P < 0.01). A glucagon response from normal human islets using the same experimental design was also observed. A glucagon response (peak change within 7 rain after switch off = 31 ± 1 pg/ml, n = 3, P < 0.01) was observed from β-cell-depleted, STZ-induced diabetic rats whose islets still secreted small amounts of insulin. However, when these islets were first perifused with both exogenous insulin and 16.7 mmol/l glucose, followed by switching off both the insulin and glucose perifusate, a significantly larger (P < 0.05) glucagon response was observed (peak change within 7 min after switch off = 71 ± 11 pg/ml, n = 4, P < 0.01). This response was not observed if the insulin perifusion was not switched off when the islets were deprived of glucose or when insulin was switched off without glucose deprivation. These data uniquely demonstrate that both normal, isolated islets and islets from STZ-administered rats can respond to glucose deprivation by releasing glucagon if they are first provided with increased endogenous or exogenous insulin. These results fully support the β-cell switch-off hypothesis as a key mechanism for the α-cell response to hypoglycemia. [ABSTRACT FROM AUTHOR]

Several human and animal Ebola outbreaks have occurred over the past 4 years in Gabon and the Republic of Congo. The human outbreaks consisted of multiple simultaneous epidemics caused by different viral strains, and each epidemic resulted from the handling of a distinct gorilla, chimpanzee, or duiker carcass. These animal populations declined markedly during human Ebola outbreaks, apparently as a result of Ebola infection. Recovered carcasses were infected by a variety of Ebola strains, suggesting that Ebola outbreaks in great apes result from multiple virus introductions from the natural host. Surveillance of animal mortality may help to predict and prevent human Ebola outbreaks. [ABSTRACT FROM AUTHOR]

In a previous paper, the kinetic behavior of a cyanate ester trimerization was studied. In this paper, the thermophysical properties (heat capacity, thermal conductivity) are measured and modeled (as a function of temperature and conversion) for the neat resin and for a glass fibers composite. These models (thermophysical and kinetics) are used to simulate the thermal transfers in an instrumented heated mold. The calculated local temperatures and surface heat fluxes appear to be in very good agreement with measurements, for both the neat resin and the composite. [Copyright &y& Elsevier]

Examines the role of interleukin-7 (IL-7) for homeostatic proliferation and survival of naive T cells. Response of naive T cells during contact with self-MHC/peptide ligand; Disappearance of naive T cells upon adoptive transfer into IL-7-host; Restoration of homeostatic proliferation in IL-7.

Positive selection has long been thought to be a devise for producing a repertoire of T cells that can efficiently recognize foreign peptides in the context of self-major histocompatibility complex (MHC) molecules. However, in the light of recent evidence that long-term survival of mature T cells requires continuous contact with self-MHC molecules, the possibility for an additional role for positive selection has emerged: to generate a repertoire of T cells that can be maintained in the periphery through contact with self-MHC/peptide ligands. In support of this idea, our recent work suggests that positive selection is highly peptide specific and, more important, that mature T cells require extrathymic contact with the same MHC/peptide ligands that initially induced positive selection in the thymus in order for prolonged survival and to undergo homeostatic proliferation in response to T cell deficiency. [ABSTRACT FROM AUTHOR]

Despite the probable zoonotic origin of SARS-CoV-2, only limited research efforts have been made to understand the role of companion animals in SARS-CoV-2 epidemiology. According to recent serological prevalence studies, human-to-companion animal transmission is quite frequent, which led us to consider that the risk of SARS-CoV-2 transmission from animal to human, albeit negligible in the present context, may have been underestimated. In this study, we provide the results of a prospective survey that was conducted to evaluate the SARS-CoV-2 isolation rate by qRT-PCR in dogs and cats with different exposure risks and clinical statuses. From April 2020 to April 2021, we analyzed 367 samples and investigated the presence of SARS-CoV-2 RNA using qRT-PCR. Only four animals tested positive, all of them being cats. Three cats were asymptomatic and one presented a coryza-like syndrome. We describe in detail the infection in two cats and the associated clinical characteristics. Importantly, we obtained SARS-CoV-2 genomes from one infected animal and characterized them as Alpha variants. This represents the first identification of the SARS-CoV-2 Alpha variant in an infected animal in France. [ABSTRACT FROM AUTHOR]

In 2014, Ebola virus (EBOV) was identified as the etiological agent of a large and still expanding outbreak of Ebola virus disease (EVD) in West Africa and a much more confined EVD outbreak in Middle Africa. Epidemiological and evolutionary analyses confirmed that all cases of both outbreaks are connected to a single introduction each of EBOV into human populations and that both outbreaks are not directly connected. Coding-complete genomic sequence analyses of isolates revealed that the two outbreaks were caused by two novel EBOV variants, and initial clinical observations suggest that neither of them should be considered strains. Here we present consensus decisions on naming for both variants (West Africa: “Makona”, Middle Africa: “Lomela”) and provide database-compatible full, shortened, and abbreviated names that are in line with recently established filovirus sub-species nomenclatures.

Sequence determination of complete or coding-complete genomes of viruses is becoming common practice for supporting the work of epidemiologists, ecologists, virologists, and taxonomists. Sequencing duration and costs are rapidly decreasing, sequencing hardware is under modification for use by non-experts, and software is constantly being improved to simplify sequence data management and analysis. Thus, analysis of virus disease outbreaks on the molecular level is now feasible, including characterization of the evolution of individual virus populations in single patients over time. The increasing accumulation of sequencing data creates a management problem for the curators of commonly used sequence databases and an entry retrieval problem for end users. Therefore, utilizing the data to their fullest potential will require setting nomenclature and annotation standards for virus isolates and associated genomic sequences. The National Center for Biotechnology Information’s (NCBI’s) RefSeq is a non-redundant, curated database for reference (or type) nucleotide sequence records that supplies source data to numerous other databases. Building on recently proposed templates for filovirus variant naming [ ()////-], we report consensus decisions from a majority of past and currently active filovirus experts on the eight filovirus type variants and isolates to be represented in RefSeq, their final designations, and their associated sequences.

Embedding silicon nanoparticles in an intermetallic matrix is a promising strategy to produce remarkable bulk anode materials for lithium-ion (Li-ion) batteries with low potential, high electrochemical capacity and good cycling stability. These composite materials can be synthetized at a large scale using mechanical milling. However, for Si-Ni3Sn4 composites, milling also induces a chemical reaction between the two components leading to the formation of free Sn and NiSi2, which is detrimental to the performance of the electrode. To prevent this reaction, a modification of the surface chemistry of the silicon has been undertaken. Si nanoparticles coated with a surface layer of either carbon or oxide were used instead of pure silicon. The influence of the coating on the composition, (micro)structure and electrochemical properties of Si-Ni3Sn4 composites is studied and compared with that of pure Si. Si coating strongly reduces the reaction between Si and Ni3Sn4 during milling. Moreover, contrary to pure silicon, Si-coated composites have a plate-like morphology in which the surface-modified silicon particles are surrounded by a nanostructured, Ni3Sn4-based matrix leading to smooth potential profiles during electrochemical cycling. The chemical homogeneity of the matrix is more uniform for carbon-coated than for oxygen-coated silicon. As a consequence, different electrochemical behaviors are obtained depending on the surface chemistry, with better lithiation properties for the carbon-covered silicon able to deliver over 500 mAh/g for at least 400 cycles. [ABSTRACT FROM AUTHOR]

Based on a large study conducted on wild great ape fecal samples collected in regions of Gabon where previous human outbreaks of Ebola virus disease have occurred between 1994 and 2002, we provide evidence for prevalence of Zaire ebolavirus (EBOV)-specific antibodies of 3.9% (immunoglobulin G (IgG)) and 3.5% (immunoglobulin M (IgM)) in chimpanzees and 8.8% (IgG) and 2.4% (IgM) in gorillas. Importantly, we observed a high local prevalence (31.2%) of anti-EBOV IgG antibodies in gorilla samples. This high local rate of positivity among wild great apes raises the question of a spatially and temporally localized increase in EBOV exposure risk and the role that can be played by these animals as sentinels of the virus's spread or reemergence in a given area. [ABSTRACT FROM AUTHOR]

This paper gives some insights into the fabrication process of a heterogeneous structured β-metastable type Ti-24Nb-4Zr-8Sn alloy, and the associated mechanical properties optimization of this biocompatible and low elastic modulus material. The powder metallurgy processing route includes both low energy mechanical ball milling (BM) of spherical and pre-alloyed powder particles and their densification by Spark Plasma Sintering (SPS). It results in a heterogeneous microstructure which is composed of a homogeneous 3D network of β coarse grain regions called "core" and α/β dual phase ultra-fine grain regions called "shell." However, it is possible to significantly modify the microstructural features of the alloy—including α phase and shell volume fractions—by playing with the main fabrication parameters. A focus on the role of the ball milling time is first presented and discussed. Then, the mechanical behavior via shear tests performed on selected microstructures is described and discussed in relation to the microstructure and the probable underlying deformation mechanism(s). [ABSTRACT FROM AUTHOR]

An outbreak of febrile illness occurred in Gabon in 2007, with 20,000 suspected cases. Chikungunya or dengue-2 virus infections were identified in 321 patients; 8 patients had documented co-infections. Aedes albopictus was identified as the principal vector for the transmission of both viruses. [ABSTRACT FROM AUTHOR]

Hepatitis B virus (HBV) infection leads to around 800,000 deaths yearly and is considered to be a major public health problem worldwide. However, HBV origins remain poorly understood. Here, we looked for bat HBV (BtHBV) in different bat species in Gabon to investigate the role of these animals as carriers of ancestral hepadnaviruses because these viruses are much more diverse in bats than in other host species. DNA was extracted from 859 bat livers belonging to 11 species collected in caves and villages in the southeast of Gabon and analyzed using PCRs targeting the surface gene. Positive samples were sequenced using the Sanger method. BtHBV DNA was detected in 64 (7.4%) individuals belonging to eight species mainly collected in caves. Thirty-six (36) sequences among the 37 obtained after sequencing were phylogenetically close to the RBHBV strain recently isolated in Gabonese bats, while the remaining sequence was close to a rodent HBV strain isolated in America. The generalized linear mixed model showed that the variable species best explained the occurrence of BtHBV infection in bats. The discovery of a BtHBV strain homologous to a rodent strain in bats raises the possibility that these animals may be carriers of ancestral hepadnaviruses. [ABSTRACT FROM AUTHOR]