Brain volume increase and neuronal plasticity underly predator-induced morphological defense expression in Daphnia longicephala.

Predator-induced phenotypic plasticity describes the ability of prey to respond to an increased predation risk by developing adaptive phenotypes. Upon the perception of chemical predator cues, the freshwater crustacean Daphnia longicephala develops defensive crests against its predator Notonecta spec. (Heteroptera). Chemical predator perception initiates a cascade of biological reactions that leads to the development of these morphological features. Neuronal signaling is a central component in this series, however how the nervous system perceives and integrates environmental signals is not well understood. As neuronal activity is often accompanied by functional and structural plasticity of the nervous system, we hypothesized that predator perception is associated with structural and functional changes of nervous tissues. We observe structural plasticity as a volume increase of the central brain, which is independent of the total number of brain cells. In addition, we find functional plasticity in form of an increased number of inhibitory post-synaptic sites during the initial stage of defense development. Our results indicate a structural rewiring of nerve-cell connections upon predator perception and provide important insights into how the nervous system of prey species interprets predator cues and develops cost-benefit optimized defenses.

Endoscopic recanalization of a portoenterostomy.

Sudden cessation of bile flow occurred in an infant with biliary atresia following successful portoenterostomy. Bile flow was re-established by an endoscopic recanalization procedure, and has been sustained during 1 yr of follow-up.

Discordance in the sizing of abdominal aortic aneurysm and its significance.

Much of the confusion surrounding the repair of asymptomatic abdominal aortic aneurysms related to inaccuracies in their measurement, both preoperatively and intraoperatively. Multiple measurements of aneurysms at operation have convinced us that the largest and least variable diameter is the anteroposterior diameter measured from aortic wall anteriorly to vertebral bodies posteriorly. This AP-to-spine distance is accurately predicted by ultrasonography to within 0.3 cm. Computerized tomography does no better. plain radiography is accurate but seldom applicable. When properly estimated, aneurysm size can be accurately determined preoperatively by either ultrasonography, computerized tomography, or plain radiography, in that order of preference. Since the decision to operate on asymptomatic aneurysms is based largely on their size, accurate preoperative estimation is essential.

Management of central venous catheters using a wire introducer.

The wire introducer method is a satisfactory technique for management of central venous catheters if bacteriologic monitoring of the removed catheter is used to determine whether the introduced catheter should be allowed to remain. The data indicate that when central venous catheters become infected, they do so through the whole length of the catheter, from subcutaneous tunnel to intravascular tip. An intravenous catheter which produces negative cultures can be safely changed by the introducer method aseptically. An infected catheter must be removed as soon as the diagnosis is apparent, since the replacement catheter will be seeded by the colonized tract. Blood specimens drawn through central venous lines do not reflect the status of the line itself but rather the presence or absence of systemic bacteremia.

Role of different methods of lung biopsy in the diagnosis of lung lesions.

Bronchoscopic biopsy and percutaneous needle biopsy were retrospectively compared with open biopsy. No procedure resulted in mortality. Nonfatal complications were similar in incidence. Bronchoscopic biopsy approached the accuracy of open biopsy only when applied to infiltrates. Percutaneous needle biopsy approached the accuracy of open biopsy only when applied to nodules. Nonspecific results of either bronchoscopic biopsy or percutaneous needle biopsy were unacceptable as definitive diagnoses.