High-sensitivity rod photoreceptor input to the blue-yellow color opponent pathway in macaque retina.

Small bistratified cells (SBCs) in the primate retina carry a major blue-yellow opponent signal to the brain. We found that SBCs also carry signals from rod photoreceptors, with the same sign as S cone input. SBCs exhibited robust responses under low scotopic conditions. Physiological and anatomical experiments indicated that this rod input arose from the AII amacrine cell-mediated rod pathway. Rod and cone signals were both present in SBCs at mesopic light levels. These findings have three implications. First, more retinal circuits may multiplex rod and cone signals than were previously thought to, efficiently exploiting the limited number of optic nerve fibers. Second, signals from AII amacrine cells may diverge to most or all of the approximately 20 retinal ganglion cell types in the peripheral primate retina. Third, rod input to SBCs may be the substrate for behavioral biases toward perception of blue at mesopic light levels.

Dr. William Gorgas and his style of management against yellow fever during the construction of the Panama Canal: A historical case study

This study describes the style of management of Dr. William Gorgas as he led the public health effort to reduce diseases to a level that permitted the completion of the Panama Canal construction. Initially, Gorgas was skeptical of the mosquito vector theory. He fully accepted this theory after participating in Walter Reed’s massive cleanup of Havana, Cuba during the Spanish American War of 1898. During 1905 to 1914, Gorgas was selected to lead the sanitary effort during the construction of the Panama Canal. The lessons learned from this historical case study provide public health administrators with guidance to effectively lead current and future infectious diseases threats. Understanding styles of management within the context of disease control is essential in tackling epidemics like yellow fever and other infectious diseases. ^

TRANSOVARIAL TRANSMISSION OF YELLOW FEVER VIRUS BY A SYLVATIC VECTOR, HAEMAGOGUS EQUINUS (THEOBALD)

The potential of a sylvatic vector to act as reservoir of yellow fever virus was assessed in Haemagogus equinus (Theobald). Mosquitoes from the Maje'75 laboratory colony and a Panamanian human isolated strain of yellow fever virus were used. Female mosquitoes infected with yellow fever virus had a minimum transovarial transmission rate of 1:5745. This is the first time transovarial transmission of yellow fever virus has been demonstrated in a New World sylvatic vector. Transovarial transmission of yellow fever virus in this sylvatic mosquito species may be an alternative mechanism for biological survival of the virus during adverse periods or in the absence of susceptible vertebrate hosts. ^

Effects of a dog walking program with older adults in long-term care

The purpose of this study was to determine if walking a dog would increase motivation to adhere to a walking program and result in an increase in walking endurance and mobility among institutionalized elderly. An experimental pre and post test two group randomly assigned study design was utilized. Thirty subjects, 20 females and 10 males with an average age of 72, were enrolled from three long-term care facilities. The walking program was 3 times a week for 6 weeks. The experimental group walked with a certified therapy dog and the handler. The control group walked with only the handler. The Outcome Expectations for Exercise Scale (OEES) was used to measure the perceived benefits of exercise. The 2-minute walk test and the 30 second chair stand test were administered before and after the walking program. The OEES scores did not significantly predict adherence to the program. The pre- and post-chair stand test and the 2-minute walk test did not show statistical significant differences between groups. All of the participants did show an increase (7 minutes) in walking time during the 6 week period (p=0.048). The mean pre and post walk test scores for participants with stroke/arthritis were significantly less than those without stroke/arthritis (p=0.013). The experimental group had 12 subjects with stroke/arthritis compared with 6 in the control group. The walk test means in feet walked were 362.44 ± 130.36 (control) vs. 201.27 ± 106.25 (experimental), p=0.001. The results indicate walking practice has the potential to increase walking time and endurance. Because residents of long-term care facilities were not allowed outside the facilities without accompaniment, the presence of the dog handler was key to their walking. Analysis of conversations during the walks indicated that for participants who walked with dogs, the dogs did serve as motivation for continuing in the program. ^