Two Determinants of Dynamic Adaptive Learning for Magnitudes and Probabilities.

Humans face a dynamic world that requires them to constantly update their knowledge. Each observation should influence their knowledge to a varying degree depending on whether it arises from a stochastic fluctuation or an environmental change. Thus, humans should dynamically adapt their learning rate based on each observation. Although crucial for characterizing the learning process, these dynamic adjustments have only been investigated empirically in magnitude learning. Another important type of learning is probability learning. The latter differs from the former in that individual observations are much less informative and a single one is insufficient to distinguish environmental changes from stochasticity. Do humans dynamically adapt their learning rate for probabilities? What determinants drive their dynamic adjustments in magnitude and probability learning? To answer these questions, we measured the subjects' learning rate dynamics directly through real-time continuous reports during magnitude and probability learning. We found that subjects dynamically adapt their learning rate in both types of learning. After a change point, they increase their learning rate suddenly for magnitudes and prolongedly for probabilities. Their dynamics are driven differentially by two determinants: change-point probability, the main determinant for magnitudes, and prior uncertainty, the main determinant for probabilities. These results are fully in line with normative theory, both qualitatively and quantitatively. Overall, our findings demonstrate a remarkable human ability for dynamic adaptive learning under uncertainty, and guide studies of the neural mechanisms of learning, highlighting different determinants for magnitudes and probabilities.

Gated recurrence enables simple and accurate sequence prediction in stochastic, changing, and structured environments.

From decision making to perception to language, predicting what is coming next is crucial. It is also challenging in stochastic, changing, and structured environments; yet the brain makes accurate predictions in many situations. What computational architecture could enable this feat? Bayesian inference makes optimal predictions but is prohibitively difficult to compute. Here, we show that a specific recurrent neural network architecture enables simple and accurate solutions in several environments. This architecture relies on three mechanisms: gating, lateral connections, and recurrent weight training. Like the optimal solution and the human brain, such networks develop internal representations of their changing environment (including estimates of the environment's latent variables and the precision of these estimates), leverage multiple levels of latent structure, and adapt their effective learning rate to changes without changing their connection weights. Being ubiquitous in the brain, gated recurrence could therefore serve as a generic building block to predict in real-life environments.

Initial Reintroduction of the Aye-Aye (Daubentonia madagascariensis) in Anjajavy Reserve, Northwestern Madagascar.

Madagascar's biodiversity is imperiled by habitat loss and degradation. Furthermore, species may be locally extirpated due to targeted hunting or disease. Translocating at-risk individuals to areas devoid of the species may be an effective conservation intervention. The aye-aye, Daubentonia madagascariensis, is uniquely susceptible to hunting pressure due to a cultural superstition. In June 2018, we reintroduced two aye-ayes in the Anjajavy Reserve, a dry deciduous forest in northwestern Madagascar. The translocated individuals, an adult female and juvenile offspring, were rescued from a neighboring forest that was subjected to pressure from fires and logging. We safely secured and transported the aye-ayes to Anjajavy and put them in a quarantine enclosure, where they were subjected to biomedical and behavioral monitoring. After release in the adjacent, protected forest, we conducted postrelease monitoring of the adult female using radio-tracking and scan sampling to determine ranging and activity patterns. We conducted behavioral observations from October 2018 to February 2019 and collected sleeping site data from October 2018 to September 2019. The female aye-aye fed on local resources including Canariumsp. seeds. During the study period, the aye-aye used 31 nests, occupied a home range of approximately 85 ha and traveled, on average, at a pace of 320 m/h. Our findings are comparable with published data on wild aye-ayes in other regions of Madagascar and provide support for future reintroductions of adult aye-ayes, and potentially other endemic species to the natural and protected habitats of Anjajavy.

Factors associated with unfavorable outcome in a multicenter audit of 100 infective endocarditis.

We aimed to identify factors associated with unfavorable outcome in patients treated for infective endocarditis (IE), with a focus on departure from European guidelines. We conducted a retrospective audit of all adult patients treated for endocarditis during a 1-year period across a regional network of nine care centers in the south-east of France. Medical records were reviewed regarding patient and infection characteristics, antibiotic therapy, outcome, and compliance to the European Society of Cardiology guidelines. Antibiotic treatment appropriateness was evaluated regarding molecule, dosage, and duration, according to guidelines. Primary endpoint was the assessment of factors associated with unfavorable outcome, defined as in-hospital mortality or IE relapse at 1-year follow-up. Secondary endpoints were intensive care admission, iatrogenic events, and nosocomial infections that occurred during hospital stay. One hundred patients were included. Median age was 71 years old. Twenty-two patients died and IE relapse occurred in two patients, representing 24 patients with unfavorable outcome. Overall, antibiotic treatment was deemed appropriate in 28 cases. Thirty-three patients required intensive care, 34 iatrogenic events were found, including 19 acute kidney injuries, and 13 nosocomial infections occurred during care. Using a logistic regression, factors associated with unfavorable outcome were admission in the intensive care unit (adjusted odd ratio 7.26 [1.8-29.28]; p = 0.005), new-onset nosocomial infection (adjusted odd ratio 8.83 [1.42-54.6]; p = 0.019), and age > 71 years old (adjusted odd ratio 11.2 [2.76-46.17]; p < 0.001). Departure from guidelines was frequent but not related to unfavorable outcome in our study. Only intensive care, age, and nosocomial infections were associated with mortality and relapse. Iatrogenic events were numerous, with no impact on outcome.

The effect of a single dose of oral ivermectin on pruritus in the homeless.

BACKGROUND: Homeless people commonly present with ectoparasite-based pruritus. We evaluated the efficacy of a single dose of ivermectin to reduce the pruritus prevalence in a homeless population. METHODS: We conducted a randomized, double-blind, placebo-controlled trial from January 2006 to April 2006 in two homeless shelters in the city of Marseille, France. Homeless people complaining of pruritus were randomized to receive either ivermectin (24 mg) or placebo. Follow-up visits were planned at day 14 and day 28 after the inclusion to assess the outcome of pruritus. RESULTS: Forty-two subjects with pruritus were randomized to the ivermectin group and 40 to the placebo group. On day 14, pruritus was reported by significantly more subjects in the placebo group than those in the ivermectin group for both the per-protocol (PP) population (91.42% versus 68.57%, P = 0.014) and the intention-to-treat (ITT) population (92.5% versus 73.80%, P = 0.038). No significant effect was observed at day 28. Ivermectin was the only independent factor associated with the absence of pruritus at day 14 in both PP population [OR: 4.60 (95% CI:1.13; 18.73), P = 0.033] and ITT population [OR: 4.38 (95% CI: 1.07; 17.77), P = 0.039]. CONCLUSIONS: A single dose of oral ivermectin has a transient beneficial effect on the reduction of the prevalence of pruritus in the homeless population. More studies are required to assess the efficacy of multiple repeated treatments with ivermectin to reduce scabies and body lice endemic among homeless people with pruritus and the impact of such treatment on this population.

How to fight antimicrobial resistance.

Antimicrobial misuse results in the development of resistance and superbugs. Over recent decades, resistance has been increasing despite continuing efforts to control it, resulting in increased mortality and cost. Many authorities have proposed local, regional and national guidelines to fight against this phenomenon, and the usefulness of these programmes has been evaluated. Multifaceted intervention seems to be the most efficient method to control antimicrobial resistance. Monitoring of bacterial resistance and antibiotic use is essential, and the methodology has now been homogenized. The implementation of guidelines and infection control measures does not control antimicrobial resistance and needs to be reinforced by associated measures. Educational programmes and rotation policies have not been evaluated sufficiently in the literature. Combination antimicrobial therapy is inefficient in controlling antimicrobial resistance.

Fever in travelers returning from tropical areas: prospective observational study of 613 cases hospitalised in Marseilles, France, 1999-2003.

BACKGROUND: Febrile travelers may pose a diagnostic challenge for Western physicians who are frequently involved in the assessment of these patients but unfamiliar with tropical diseases. Evaluation of this situation requires an understanding of the common etiologies, which are associated with the demographics of travelers and the destinations. METHODS: We conducted a 5-year prospective observational study on the etiologies of fever in travelers returning from the tropics admitted to the infectious and tropical diseases unit of a university teaching hospital in Marseilles, France. RESULTS: A total of 613 patients were enrolled, including 364 migrants (59.4%), 126 travelers (20.6%), 37 visitors (6%), 24 expatriates (3.9%), and 62 patients (10.1%) who could not be classified. Malaria was the most common diagnosis (75.2%), with most cases (62%) acquired by migrants from the Comoros archipelago and who had traveled to these islands to visit friends and relatives. Agents of food-borne and water-borne infections (3.9%) and respiratory tract infections (3.4%) were also frequently identified as the cause of fever. Other infections included emerging diseases such as gnathostomiasis, hepatitis E infection and rickettsial diseases, as well as common infections or exotic diseases. CONCLUSIONS: Although we have identified here various causes of imported fever, 8.2% of the fevers remained unexplained. An improved approach to diagnosis may allow for the discovery of new diseases in travelers in the future.

Report of two fatal cases of Mycobacterium mucogenicum central nervous system infection in immunocompetent patients.

Neurological infections due to rapidly growing mycobacteria (RGM) have rarely been reported. We recently investigated two unrelated immunocompetent patients, one with community-acquired lymphocytic meningitis and the other with cerebral thrombophlebitis. Mycobacterium mucogenicum was isolated in pure culture and detected by PCR sequencing of cerebrospinal fluid samples. Both patients eventually died. The two isolates exhibited an overlapping antimicrobial susceptibility pattern. They were susceptible in vitro to tetracyclines, macrolides, quinolones, amikacin, imipenem, cefoxitin, and trimethoprim-sulfamethoxazole and resistant to ceftriaxone. They shared 100% 16S rRNA gene sequence similarity with M. mucogenicum ATCC 49650T over 1,482 bp. Their partial rpoB sequences shared 97.8% and 98.1% similarity with M. mucogenicum ATCC 49650T, suggesting that the two isolates were representative of two sequevars of M. mucogenicum species. This case report should make clinicians aware that M. mucogenicum, an RGM frequently isolated from tap water or from respiratory specimens and mostly without clinical significance, can even be encountered in the central nervous system of immunocompetent patients.

Bartonella quintana characteristics and clinical management.

Bartonella quintana, a pathogen that is restricted to human hosts and louse vectors, was first characterized as the agent of trench fever. The disease was described in 1915 on the basis of natural and experimental infections in soldiers. It is now recognized as a reemerging pathogen among homeless populations in cities in the United States and Europe and is responsible for a wide spectrum of conditions, including chronic bacteremia, endocarditis, and bacillary angiomatosis. Diagnosis is based on serologic analysis, culture, and molecular biology. Recent characterization of its genome allowed the development of modern diagnosis and typing methods. Guidelines for the treatment of B. quintana infections are presented.

Oral ivermectin in the treatment of body lice.

The mainstays of treatment of body-louse infestation in humans in a community setting are insecticides and the removal of infested clothing. We report here the dramatic effect that 3 doses of oral ivermectin (12 mg each), administered at 7-day intervals, have in reducing the total number of body lice in a cohort of homeless men from a shelter in Marseilles, France. We identified a baseline total of 1898 lice in the cohort. Over a 14-day period, this number fell to 6 lice; the prevalence of infested individuals fell from 84.9% to 18.5%. Although this effect was not sustained at day 45, it establishes that ivermectin plays a novel role in the control of body-louse infestation in humans.

Short report: Q fever and Plasmodium falciparum malaria co-infection in a patient returning from the Comoros archipelago.

Although Plasmodium falciparum malaria and Q fever are both prevalent in Africa, there have been no reports of co-infection to date. We report a case who returned from the Comoros archipelago diagnosed by serologic analysis as well as detection of Coxiella burnetii DNA in acute-phase serum. Thus, Q fever may be associated with malaria infection in travelers returning from disease-endemic countries. This diagnosis should be considered when the response to malaria treatment is incomplete.

Acute cytomegalovirus infection complicated by venous thrombosis: a case report.

BACKGROUND: CMV-induced vasculopathy and thrombosis have been reported, but they are rare conditions usually encountered in immunocompromised patients. However more and more complications of CMV infections are recognized in immunocompetent patients. CASE PRESENTATION: We present a case report of a previously healthy adult with cytomegalovirus infection that was complicated by tibiopopliteal deep venous thrombosis and in whom Factor V Leiden heterozygous mutation was found. CONCLUSION: This new case report emphasizes the involvement of cytomegalovirus in induction of vascular thrombosis in patients with predisposing risk factors for thrombosis. It is necessary to screen for CMV infection in patients with spontaneous thrombosis and an history of fever.

Veillonella montpellierensis endocarditis.

Veillonella spp. rarely cause infections in humans. We report a case of Veillonella endocarditis documented by isolating a slow-growing, gram-negative microbe in blood cultures. This microbe was identified as the newly recognized species Veillonella montpellierensis (100% homology) by 16S RNA gene sequence analysis.

Severe transient neutropenia associated with acute human immunodeficiency virus type 1 infection.

Severe neutropenia associated with primary HIV infection is unusual. We report the fifth case in a 50-year-old male with a neutrophil count of 500/mm(3) and a platelet count of 92,000/mm(3) at the time of early HIV-1 seroconversion. In all previously published cases and in our case, severe neutropenia was a very early sign of acute HIV infection, and it regressed spontaneously and quickly. HIV testing should be recommended when severe neutropenia is observed, especially in the context of a flu-like or mononucleosis-like infectious syndrome.

Bartonella quintana in human erythrocytes.

Bartonella quintana is transmitted by body lice among homeless people. Infection with this organism leads to chronic bacteraemia with few symptoms. We looked for B quintana in erythrocytes in a population of homeless people in Marseille, France. In this report we show the intraerythrocytic presence of B quintana in people with symptomless bacteraemia, by use of a specific monoclonal antibody and laser confocal microscopy. Presence of at least 5 x 10(4) colony-forming units per mL was predictive of intracellular infection. However, such infection was not associated with evidence of haemolysis. Colonisation of erythrocytes could allow efficient transmission of B quintana by body lice.