Cognitive Tagging of Neurons: CREMediated Genetic Labeling and Characterization of the Cells Involved in Learning and Memory.

In this study, we describe use of Cre-mediated recombination to obtain a permanent genetic labeling of the brain neuronal networks activated during a new experience in animals. This method utilizes bitransgenic Fos-Cre-eGFP mice in which a green fluorescent protein is expressed upon tamoxifen-induced Cre-recombination only in the cells where immediate early gene c-fos expression takes place due to the new experience. We used the classical fear conditioning model to show that ex vivo microscopy of the eGFP protein in Fos-Cre-eGFP mice enables mapping of the neurons of the various brain regions that undergo Cre-recombination during acquisition of a new experience. We exposed the animals to the new environment in brief sessions and demonstrated that double immunohistochemical staining enables a characterization of the types of neocortical and hippocampal neurons that undergo experience-dependent Cre-recombination. Notably, Fos-Cre-eGFP labeled cells appeared to belong to excitatory pyramidal neurons rather than to various types of inhibitory neurons. We also showed that a combination of genetic Cre-eGFP labeling with immunohistochemical staining of the endogenous c-Fos protein allows one to identify and compare the neuronal populations that are activated during two different episodes of new experiences in the same animal. This new approach can be used in a wide spectrum of tasks that require imaging and a comparative analysis of cognitive neuronal networks.

[Long-Term Contextual Memory in Mice: Persistence and Associability with Reinforcement].

Animals can associate memory of a context with unconditioned stimuli even if there is a long time in- terval between acquisition of contextual memory and its subsequent reinforcement. This phenomenon of context preexposure effect was first described and investigated in rats. Here we studied the possibility of associating previously acquired memory about a context with unconditioned stimulus (immediate shock) in mice. We showed that fear memory in this model was specific for the previously explored context but not for the context of immediate shock. Associative learning was possible when acquisition of contextual memory and presentation unconditioned stimulus (immediate shock) were spaced in the range of 30 min-30 days interval. Resulting memory was stable and persisted for at least 30 days. Our results open new avenues for studies of neuronal mechanisms of associative memory using transgenic re- porter mice.

[Adenovirus pneumonia with a fatal outcome in adults].

AIM: To retrospectively analyze the medical records of patients who have died from complications of community-acquired pneumonia (CAP) caused by adenovirus serotype 7. SUBJECTS AND METHODS: CAP was diagnosed in patients (6 men aged 19-24 years and 1 woman aged 49 years) on the basis of clinical, laboratory, and radiological findings. Adenoviral pneumonia was established by real-time polymerase chain reaction (PCR). Adenovirus DNA was detected in the patients' autopsy samples (lungs, brain, spleen, liver, blood). The adenoviruses were referred to as B1 serotype 7 on the basis of hexone gene sequencing results. Other potential causative agents of pneumonia were excluded by a battery of molecular genetic tests for a wide range of viral and bacterial pathogens of acute respiratory tract infections. RESULTS: In all cases, the disease began acutely with fever (37.8 to 39 °C), weakness, headache, a sore throat, a dry, unproductive cough or runny nose. Clinical deterioration during symptomatic therapy led to hospital admission for CAP on disease days 2-11. The patients continued to feel worse during massive antibiotic therapy, by switching a drug one to six times and by simultaneously using 2-4 antibiotics and intensive therapy. Death occurred on disease days 10-24. Postmortem examination of all the patients revealed acute respiratory distress syndrome and multiple organ failure. CONCLUSION: Adenovirus pneumonia causes diagnostic and therapeutic problems for clinicians. The clinical introduction of PCR methods for the diagnosis of viral infections allow the clinicians to elaborate and timely use effective management tactics in patients with adenoviral pneumonia and to prevent their death. It is necessary to design etiotropic therapy agents and to introduce the specific prevention of adenovirus infection in risk groups.