Continuous anesthesia for 60 days in an isosmotic environment does not impair limb or cardiac regeneration in the axolotl.

Longitudinal animal experiments in the field of regenerative biology often require repeated use of short-term anesthesia (minutes to a few hours). Regain of consciousness limits the level of acceptable invasiveness of procedures, and it makes it difficult to untangle behavioral changes caused by injury to physiological processes involved in the regenerative response. Therefore, a method to keep a regenerative research animal in a comatose state under continuous anesthesia during regenerative experiments often spanning months, would be ethically and experimentally desirable. Here we report on a method using propofol based anesthesia in an isosmotic environment that allows for continuous anesthesia of regenerating axolotls for 60 days with a 75% survival rate, thus spanning the majority of a full regenerative cycle following limb amputation or cryoinjury to the heart. No differences were detected in the axolotl's ability to regenerate amputated limbs and cardiac cryo-injury while anesthetized, however some regenerative failures in the limb were observed in both anesthetized and unanesthetized control groups, most likely caused by prolonged fasting. Sixty days of anesthesia may be approaching a level were kidney function is affected, but the 75% surviving anesthetized animals recovered well after anesthesia and showed a full behavioral recovery within 17 days.

Opportunities and short-comings of the axolotl salamander heart as a model system of human single ventricle and excessive trabeculation.

Few experimental model systems are available for the rare congenital heart diseases of double inlet left ventricle (DILV), a subgroup of univentricular hearts, and excessive trabeculation (ET), or noncompaction. Here, we explore the heart of the axolotl salamander (Ambystoma mexicanum, Shaw 1789) as model system of these diseases. Using micro-echocardiography, we assessed the form and function of the heart of the axolotl, an amphibian, and compared this to human DILV (n = 3). The main finding was that both in the axolotl and DILV, blood flows of disparate oxygen saturation can stay separated in a single ventricle. In the axolotl there is a solitary ventricular inlet and outlet, whereas in DILV there are two separate inlets and outlets. Axolotls had a lower resting heart rate compared to DILV (22 vs. 72 beats per minute), lower ejection fraction (47 vs. 58%), and their oxygen consumption at rest was higher than peak oxygen consumption in DILV (30 vs. 17 ml min-1 kg-1). Concerning the ventricular myocardial organization, histology showed trabeculations in ET (n = 5) are much closer to the normal human setting than to the axolotl setting. We conclude that the axolotl heart resembles some aspects of DILV and ET albeit substantial species differences exist.

Evaluation of QuickFISH and maldi Sepsityper for identification of bacteria in bloodstream infection.

BACKGROUND: Early detection of bacteria and their antibiotic susceptibility patterns are critical to guide therapeutic decision-making for optimal care of septic patients. The current gold standard, blood culturing followed by subculture on agar plates for subsequent identification, is too slow leading to excessive use of broad-spectrum antibiotic with harmful consequences for the patient and, in the long run, the public health. The aim of the present study was to assess the performance of two commercial assays, QuickFISH® (OpGen) and Maldi Sepsityper™ (Bruker Daltonics) for early and accurate identification of microorganisms directly from positive blood cultures. MATERIALS AND METHODS: During two substudies of positive blood cultures, the two commercial assays were assessed against the routine method used at the clinical microbiology laboratory, Unilabs AB, at Skaraborg Hospital, Sweden. RESULTS: The Maldi Sepsityper™ assay enabled earlier microorganism identification. Using the cut-off for definite species identification according to the reference method (>2.0), sufficiently accurate species identification was achieved, but only among Gram-negative bacteria. The QuickFISH® assay was time-saving and showed high concordance with the reference method, 94.8% (95% CI 88.4-98.3), when the causative agent was covered by the QuickFISH® assay. CONCLUSIONS: The use of the commercial assays may shorten the time to identification of causative agents in bloodstream infections and can be a good complement to the current clinical routine diagnostics. Nevertheless, the performance of the commercial assays is considerably affected by the characteristics of the causative agents.