Corticosterone is produced by the adrenal glands and also produced locally by other organs, such as the brain. Local levels of corticosterone in specific brain regions during development are not known. Here, we microdissected brain tissue and developed a novel liquid chromatography tandem mass spectrometry method (LC‐MS/MS) to measure a panel of seven steroids (including 11‐deoxycorticosterone (DOC), corticosterone, and 11‐dehydrocorticosterone (DHC) in the blood, hippocampus (HPC), cerebral cortex (CC), and hypothalamus (HYP) of mice at postnatal day (PND) 5, 21, and 90. In a second cohort of mice, we measured the expression of three genes that code for steroidogenic enzymes that regulate corticosterone levels (Cyp11b1, Hsd11b1, and Hsd11b2) in the HPC, CC, and HYP. There were region‐specific patterns of steroid levels across development, including higher corticosterone levels in the HPC and HYP than in the blood at PND5. In contrast, corticosterone levels were higher in the blood than in all brain regions at PND21 and PND90. Brain corticosterone levels were not positively correlated with blood corticosterone levels, and correlations across brain regions increased with age. Local corticosterone levels were best predicted by local DOC levels at PND5, but by local DHC levels at PND21 and PND90. Transcripts for the three enzymes were detectable in all samples (with highest expression of Hsd11b1) and showed region‐specific changes with age. These data demonstrate that individual brain regions fine‐tune local levels of corticosterone during early development and that coupling of glucocorticoid levels across regions increases with age.
Culex coronator, a mosquito species common to the American tropics, has been recently documented from a number of temperate areas in the USA. Since 2002 specimens have been reported for the first time from Oklahoma, Louisiana, Mississippi, Alabama, and Florida. Here we provide new collection records for Cx. coronator in east-central Alabama. In October 2007, 2 larvae of Cx. coronator were collected from an artificial container in Tuskegee National Forest in Macon County, AL. The distribution of Cx. coronator in the USA seems to be expanding at a prodigious rate, for reasons that remain unclear.
Circadian patterns of flight activity in mosquitoes can influence pathogen transmission by regulating dispersal potential of vectors and contact rates between vectors and reservoir and/or dead-end hosts. We investigated circadian activity patterns of Culex erraticus (Dyar and Knab) at a wetland field site in central Alabama, by aspirating resting adults and questing females in the morning and evening hours, respectively. Mosquitoes were aspirated at regular time intervals to determine the time of day during which peak resting site-seeking and host-seeking activities occurred. Day-to-day variation in activity patterns due to wind, humidity, and temperature was examined using stepwise linear regression. We found a distinct peak in flight activity during the morning hours (2 h before and 2 h after sunrise) for females and males of Culex erraticus, the most commonly encountered species at the site. The exact time of the peak varied from day to day, and was largely a function of temperature. A less distinct peak in activity was observed for questing females in the evening, although flights generally commenced just after sunset and peaked 30-60 min after sunset. A significant amount of day-to-day variation in the number of questing females was attributable to relative humidity. Our study demonstrates predictable patterns of circadian activity for Cx. erraticus, a suspected bridge vector of eastern equine encephalitis virus. Moreover, these patterns are modulated by environmental conditions. This information may be used to develop vector control strategies and make predictions about factors that affect the spread of mosquito-vectored pathogens.
Measurement of capillary refill time (CRT) is thought of as a fast and inexpensive tool for assessing perfusion to an extremity or digit. CRT is frequently relied upon by orthopedic surgeons, especially in the postoperative period when pulses may be inaccessible owing to casts or dressings. Yet to our knowledge, no study has attempted to correlate CRT with other indices of perfusion to the extremity. We evaluated the association between CRT and arterial flow in pediatric upper extremities. Our hypothesis was that arterial flow would be inversely proportional to CRT--that decreased perfusion would be associated with prolonged CRT. Ten children between the ages of 8 and 17 years with no systemic or upper extremity abnormalities were studied. Radial and ulnar artery flows were evaluated with Doppler ultrasound. Measurements of the radial and ulnar flow volumes were summed, to approximate total flow to the extremity. CRT was measured to the tenth of a second with the use of digital video. Three sets of the above measurements were taken for each participant--at baseline and at two levels of decreased perfusion (produced by inflating a blood pressure cuff to 25 and 75 mmHg). Linear regression was used to analyze the data. A lack of correlation was found between arterial flow and CRT (r=0.02, P=0.93). Though the study has its weaknesses, the results caution the use of CRT as a solitary measure of perfusion in children. This was a level 1 diagnostic study.
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