Neurons in monkey prefrontal cortex whose activity tracks the progress of a three-step self-ordered task

The self-ordered task is a powerful tool for the analysis of dorsal prefrontal deficits. Each trial consists of a number of steps, and subjects must remember their choices in previous steps. The task becomes more difficult as the number of objects to be remembered increases. We recorded the activity of 156 neurons in the mid-dorsal prefrontal cortex of two rhesus monkeys performing an oculomotor version of the task. Although the task requires working memory, there was no convincing evidence for activity selective for the working memory of the objects that the monkey had to remember. Instead, nearly one-half of neurons (47%, 74/156) showed activity that was modulated according to the step of the task in any one or more task periods. Although the monkey's reward also increased with step, the neurons exhibited little or no step modulation in a reward control task in which reward increased without a concurrent increase in task difficulty. The activity of some neurons was also selective for the location of saccade target that the monkey voluntarily chose. Neurons showed less step modulation in error trials, and there was no increase between the second and third step responses on trials in which the error was on the third step. These results suggest that the mid-dorsal prefrontal cortex contributes to the self-ordered task, not by providing an object working memory signal, but by regulating some general aspect of the performance in the difficult task.     

Radiologic and patient-reported functional outcomes in an elderly cohort with conservatively treated distal radius fractures

PURPOSE: There have been few prospective studies of elderly patients with conservatively treated distal radius fractures and little is known about the relationship between acceptable radiographic reduction and functional outcomes in this population. We hypothesized that acceptable fracture reduction (according to standard radiographic dorsal/volar tilt criteria) would be associated with better functional outcomes and greater satisfaction. METHODS: Seventy-four patients who were at least 50 years of age with conservatively managed distal radius fractures were recruited from 2 large urban emergency departments from January 2001 to December 2001. Patients with wrist fractures treated in the emergency department and discharged home were included; patients admitted to the hospital or who required surgical reduction were excluded. Standard lateral radiographs were taken after the final cast was removed. These were reviewed independently by a reference-standard musculoskeletal radiologist and the degree of dorsal/volar tilt was recorded. This value was dichotomized according to standard published dorsal/volar tilt criteria as acceptable (dorsal tilt <10 degrees or volar tilt <20 degrees ) or unacceptable (dorsal tilt >10 degrees or volar tilt >20 degrees ). The Medical Outcomes Study Short-Form 12 (SF-12); the Disabilities of the Arm, Shoulder, and Hand questionnaire; and a patient satisfaction survey were used to assess patient-reported outcomes 6 months after the injury. RESULTS: The average dorsal/volar tilt measured by the reference standard radiologist was 3.4 degrees (SD=13.6) dorsal; overall 47 patients (64%) were considered to have an acceptable radiographic reduction. Acceptable radiographic reduction was not associated with better generic physical or mental health status, lesser degrees of upper-extremity disability, or greater satisfaction with outcomes than was unacceptable reduction. Overall 44 of 74 patients (59%) reported being satisfied or very satisfied with their functional status at 6 months. CONCLUSIONS: Contrary to our hypotheses we found that acceptable radiographic reduction (according to dorsal/volar tilt criteria) was not associated with better self-reported functional outcomes or increased satisfaction at 6 months in elderly patients with conservatively treated distal radius fractures.     

Health and economic impact of HIV/AIDS on South African households: a cohort study

Background  

South African households are severely affected by human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) but health and economic impacts have not been quantified in controlled cohort studies.     

The roles of co-transmission in neural network modulation

Neuromodulation provides considerable flexibility to the output of neural networks. In spite of the extensive literature documenting the presence of modulatory peptide co-transmitters in many neurons, considerably less is known about the specific roles of co-transmission in circuit function. This review describes some of the potential consequences of peptide co-transmission in functional circuits, using specific examples from recent work on the actions of identified peptidergic projection neurons acting on the multifunctional neural network within the crustacean stomatogastric ganglion. This system reveals that co-transmission provides projection neurons with a rich assortment of strategies for eliciting multiple outputs from a multifunctional network.     

Human immunodeficiency virus type 1-infected blood donors: epidemiologic, laboratory, and donation characteristics. The HIV Blood Donor Study Group

Transmission of human immunodeficiency virus type 1 (HIV-1) by homologous blood transfusion in the United States (US) is minimized by the deferral of potential donors who are at risk for HIV-1 infection and by the screening of all donations for HIV-1 antibody. HIV-1-seropositive donors at 20 blood centers were studied for information to be used in evaluating the safety of the US blood supply and making recommendations to increase that safety. From June 1988 to August 1989, 829 (0.04%) of 2,192,000 donors were found to be seropositive; 512 were interviewed. Of 388 seropositive men, 56 percent had had sex with men, 10 percent had used drugs intravenously, 8 percent had had sex with intravenous drug users, and 27 percent had no identified risk. Of 124 seropositive women, 58 percent had had sex with men at risk for HIV (81% of whom used drugs intravenously), 5 percent had used drugs intravenously, and 41 percent had no identified risk. Racial and ethnic minorities made up 68 percent of seropositive donors (black, 38%; Hispanic, 30%) and approximately 14 percent of all donors. The 157 persons with no identified risk had demographic characteristics and serologic test results for syphilis and hepatitis B that were more similar to those of HIV-1-seropositive donors with recognized risk than to those of seronegative donors. Three health care worker-blood donors (from an estimated 93,100 health care worker-donors) had infection that was probably acquired occupationally.(ABSTRACT TRUNCATED AT 250 WORDS)