Thermal acclimation and gene expression in rainbow smelt: Changes in the myotomal transcriptome in the cold.

Rainbow smelt, Osmerus mordax, have an impressive ability to acclimate to very cold water. Rainbow smelt exposed to cold (<5 °C) for an extended period of time have faster sustained swimming speeds and increased contraction kinetics in their myotomal muscle compared to warm acclimated fish. We used RNA Sequencing reactions (RNA-Seq) to explore how gene expression underlies thermal acclimation by muscle in these fish. Transcriptome analysis is limited in species that lack an annotated genome, such as rainbow smelt. The Trinity software package permits the de novo assembly of a rainbow smelt transcriptome with a modest learning curve. The transcriptome was then analyzed with Kallisto to quantify the abundance of each transcript represented in the full transcriptome and Sleuth to analyze the resulting RNA-seq datasets. Subsequently qPCR was used to explore patterns of thermal acclimation and gene expression for genes of metabolic and muscle contractile function. These methodologies revealed shifts in both muscle and metabolic gene expression that contribute to the thermal acclimation response in rainbow smelt. In fast-twitch, anaerobic white muscle, slow isoforms of myosin heavy and light chain tended to be down-regulated with exposure to cold in myotomal muscle, while fast isoforms were unchanged. Genes associated with protein turnover and aerobic metabolism were up-regulated in the white muscle, while those associated with anaerobic metabolism and the cell cycle were down-regulated. Collectively the results suggest that thermal acclimation to cold is complex process of apparent shifts in gene expression.

Increased levels of 4-hydroxynonenal and acrolein in the brain in preclinical Alzheimer disease.

Previous studies demonstrate increased levels of 4-hydroxynonenal (HNE) and acrolein in vulnerable brain regions of subjects with mild cognitive impairment and late-stage Alzheimer disease (LAD). Recently preclinical AD (PCAD) subjects, who demonstrate normal antemortem neuropsychological test scores but abundant AD pathology at autopsy, have become the focus of increased study. Levels of extractable HNE and acrolein were quantified by gas chromatography-mass spectrometry with negative chemical ionization, and protein-bound HNE and acrolein were quantified by dot-blot immunohistochemistry in the hippocampus/parahippocampal gyrus (HPG), superior and middle temporal gyri (SMTG), and cerebellum (CER) of 10 PCAD and 10 age-matched normal control (NC) subjects. Results of the analyses show a significant (P<0.05) increase in levels of extractable acrolein in the HPG of PCAD subjects compared to age-matched NC subjects and a significant decrease in extractable acrolein in PCAD CER. Significant increases in protein-bound HNE in HPG and a significant decrease in CER of PCAD subjects compared to NC subjects were observed. No significant alterations were observed in either extractable or protein-bound HNE or acrolein in the SMTG of PCAD subjects. Additionally, no significant differences in levels of protein carbonyls were observed in the HPG, SMTG, or CER of PCAD subjects compared to NC subjects.

Sleep-wake regulation is altered in leptin-resistant (db/db) genetically obese and diabetic mice.

Recent epidemiological and clinical studies indicate that the control of sleep-wake states may be an important factor in the regulation of energy metabolism. Leptin is a peripherally synthesized hormone that has critical signaling properties in the brain for the control of long-term energy homeostasis. In this study, we examined the hypothesis that leptin signaling exerts a role in sleep-wake regulation and that leptin may represent an important mechanistic link in the coordination of sleep-wake states and metabolism. Sleep-wake patterns were recorded in a genetic mouse model of obesity and diabetes, the db/db mouse, which harbors a mutation in a particular isoform of the leptin receptor (long form, LRb). We found that db/db mice exhibit a variety of alterations in sleep regulation, including an increase in overall sleep time, a dramatic increase in sleep fragmentation, attenuated diurnal rhythmicity in rapid eye movement sleep and non-rapid eye movement EEG delta power (a measure of sleep homeostatic drive), and a decrease in the compensatory response to acute (i.e., 6 h) sleep deprivation. The db/db mice also generated low amounts of locomotor activity and a reduction in the diurnal rhythm of activity. These results indicate that impaired leptin signaling has deleterious effects on the regulation of sleep amount, sleep architecture, and temporal consolidation of these arousal states. In summary, leptin may represent an important molecular component in the integration of sleep, circadian rhythms, and energy metabolism.

Physicians' personal malpractice experiences are not related to defensive clinical practices.

Whether personal malpractice experience is part of a tort signal prompting physicians to practice defensively is unclear. To explore this issue further, we assessed how physicians' malpractice experiences affect clinical decision making. We surveyed 1,540 physicians from four specialty groups (cardiologists, surgeons, obstetrician-gynecologists, and internists) using specialty-specific clinical scenarios. Physicians were in active private practice, were covered by a single malpractice insurer for five or more years, and worked in an eastern state. The net response rate was 54 percent (835 of 1,540) but measurable bias, based on practice characteristics, was negligible. Physicians evaluated clinical scenarios that were designed to maximize potential for finding positive defensive practices (extra tests and procedures). Then they rated how various factors influenced their decisions and answered questions on practice attitudes. The study compared management and testing recommendations among physicians with varying levels of malpractice exposure, which we defined in three separate ways. Participants were unaware of the study hypotheses. Physicians with greater malpractice experience showed no systematic differences in initial management choice or subsequent test recommendations. For example, similar percentages of internists in the top and bottom claims rate quartiles admitted a patient with syncope (78 percent versus 73 percent; p = 42), discharged a patient with nonspecific chest pain (80 percent versus 80 percent; p = .88), and delayed surgery in a patient with nonspecific changes on a electrocardiograph (58 percent versus 68 percent; p = .18). Attitudes about malpractice also did not differ with varying malpractice experience. Personal malpractice experience is not a predominant factor in the tort signal that prompts physicians to engage in defensive practices, to the extent that such practices exist.