Functional connectivity with anterior cingulate and orbitofrontal cortices during decision-making.

Recent neuroscience research is beginning to discover the brain regions involved in decision-making under uncertainty, but little is known about whether or how these regions functionally interact with each other. Here, we used event-related functional magnetic resonance imaging to examine both changes in overall activity and changes in functional connectivity during risk-taking. Results showed that choosing high-risk over low-risk decisions was associated with increased activity in both anterior cingulate and orbitofrontal cortices. Connectivity analyses revealed that largely distinct, but somewhat overlapping, cortical and subcortical regions exhibited significant functional connectivity with anterior cingulate and orbitofrontal cortices. Additionally, connectivity with the anterior cingulate in some regions, including the orbitofrontal cortex and nucleus accumbens, was modulated by the decision participants chose. These findings (1) elucidate large networks of brain regions that are functionally connected with both anterior cingulate and orbitofrontal cortices during decision-making and (2) demonstrate that the roles of orbitofrontal and anterior cingulate cortices can be functionally differentiated by examining patterns of connectivity.

Antibiotic penetration in liver infection: a case of tobramycin failure responsive to moxalactam.

A 23-year-old man sustained a severe liver laceration which subsequently became infected with Enterobacter aerogenes. Blood cultures were positive for this organism and the patient experienced sepsis. Over the course of 18 days, his bilirubin and serum creatinine increased from normal to 40 and 2.7 mg/dl, respectively. Tobramycin, clindamycin, and penicillin failed to control the infection despite in vitro sensitivity of the organism to tobramycin. Moxalactam was started as a last resort, and the symptoms of infection resolved in 12 h. Both hepatic and renal function returned to normal, and the patient was discharged without complications. Moxalactam concentrations in wound fluid exceeded serum concentrations and the usual minimum inhibitory concentration of the infecting organism. A likely explanation for response to moxalactam, in face of tobramycin failure, was that moxalactam was able to reach the site of infection.

Antibiotic penetration in abdominal infection: a case of tobramycin failure responsive to moxalactam.

A 50-year-old male developed an Enterobacter cloacae abdominal infection as the result of gangrene of a gastric remnant after gastrectomy. Aggressive antibiotic treatment with tobramycin and clindamycin was instituted, but despite documented in vitro bacterial sensitivity and high serum tobramycin levels, the patient's clinical condition worsened. Enterobacter cloacae continued to grow in the abdominal drainage cultures. As a last resort, moxalactam therapy was started. Within 36 hours, dramatic clinical improvement was seen and Enterobacter disappeared from the abdominal fluid cultures. Antibiotic assays showed that abdominal fluid contained approximately 50 percent of the simultaneous serum moxalactam concentration, while tobramycin was present in abdominal fluid at less than 15 percent of the serum concentration. In spite of bacterial sensitivity to both drugs, it is likely that moxalactam produced better results than did tobramycin, because of better tissue penetration characteristics.

Coagulum choledocholithotomy: a preliminary report.

Using the technique of coagulum pyelolithotomy, development of which was pioneered by Dees in 1943, we successfully extracted common duct stones from 17 dogs and three human beings. The canine model for pyelolithotomy was developed by producing an autogenous clot. We think Dee's technique could be applicable in common bile duct surgery.