Energy budget of the chicken foot

1. 1.|A mathematical model predicts the energy loss from a chicken foot provided the following variables are known: body temperature, air temperature, wind velocity, blood flow to the foot, and the relative partitioning of blood flow via two distinct venous returns.

2. 2.|Chickens are capable of keeping their feet from freezing at temperatures as low as −30°C ambient, but at a high energy cost.

3. 3.|Chickens can modulate blood flow to their feet at thermoneutral temperatures enough to vary heat loss to environment by about one-fourth metabolic heat production.

Heterogeneous activity of the human genioglossus muscle assessed by multiple bipolar fine-wire electrodes.

Genioglossus (GG) electrical activity [measured by electromyogram (EMGgg)] is best measured by intramuscular electrodes; however, the homogeneity of EMGgg is undefined. We investigated the relationships between EMGgg and the site from which activity was measured to determine whether and to what extent inhomogeneity in activity occurred. Eight healthy human volunteers underwent ultrasound to determine GG depth and width. Four pairs of electrodes were then inserted percutaneously into the left and right GG muscle, anteriorly and posteriorly. Additional configurations were obtained by connecting electrodes across the midline and along each muscle belly. EMGgg activity was simultaneously recorded from these 10 configurations at rest and during various respiratory maneuvers. Heterogeneous behavior of the GG was evidenced by 1) the variable presence of phasic EMGgg at rest, which was undetectable in two subjects but evident in 65% of configurations in six subjects and present in all configurations in all subjects during voluntary hyperventilation; 2) a greater amplitude of EMGgg response to pharyngeal square-wave negative pressure in anterior than posterior configurations (14.1 +/- 7.1 vs. 8.5 +/- 5.1% of maximum, P < 0.05); and 3) variable (linear and alinear) relationships between EMGgg and lingual force within and between subjects. We hypothesize that regional differences in density and type of muscle fiber are the most likely sources of heterogeneity in these responses.     

Tissue distribution of a plasmid DNA encoding Hsp65 gene is dependent on the dose administered through intramuscular delivery

In order to assess a new strategy of DNA vaccine for a more complete understanding of its action in immune response, it is important to determine the in vivo biodistribution fate and antigen expression. In previous studies, our group focused on the prophylactic and therapeutic use of a plasmid DNA encoding the Mycobacterium leprae 65-kDa heat shock protein (Hsp65) and achieved an efficient immune response induction as well as protection against virulent M. tuberculosis challenge. In the present study, we examined in vivo tissue distribution of naked DNA-Hsp65 vaccine, the Hsp65 message, genome integration and methylation status of plasmid DNA. The DNA-Hsp65 was detectable in several tissue types, indicating that DNA-Hsp65 disseminates widely throughout the body. The biodistribution was dose-dependent. In contrast, RT-PCR detected the Hsp65 message for at least 15 days in muscle or liver tissue from immunized mice. We also analyzed the methylation status and integration of the injected plasmid DNA into the host cellular genome. The bacterial methylation pattern persisted for at least 6 months, indicating that the plasmid DNA-Hsp65 does not replicate in mammalian tissue, and Southern blot analysis showed that plasmid DNA was not integrated. These results have important implications for the use of DNA-Hsp65 vaccine in a clinical setting and open new perspectives for DNA vaccines and new considerations about the inoculation site and delivery system.     

The uptake and efflux of glycine from rat cerebral-cortex slices

The kinetics of the influx and efflux of radioactive l-glycine was studied in slices of rat cerebral cortex. The influx showed saturation kinetics and was inhibited by l-alanine. Influx was dependent on the presence of Na(+) ions and a metabolizable substrate. The efflux of glycine was accelerated by alanine. It was concluded that carrier-mediated facilitated diffusion was the mechanism of glycine uptake by, and efflux from, cerebral slices.