Circadian rhythms in Neurospora crassa: a mutation affecting temperature compensation.

The circadian rhythm of conidiation (spore formation) in Neurospora crassa is known to be temperature compensated, that is, the period is only slightly affected by the incubation temperature. Thus, the Q10 (the relative rate enhancement corresponding to a 10 degrees C rise in temperature) of the rhythm of the bd csp strain from 14 to 30 degrees C was 1.1, whereas the Q10 of the uncompensated growth rate in the same interval was 2.4. A mutation at the cel locus resulted in loss of the temperature-compensation property in cultures grown below 22 degrees C. The Q10 of the rhythm below 22 degrees C was 2.2, and periods of about 40 hr were observed. In contrast, the Q10 of the rhythm above 22 degrees C was 1.1, with circadian periods of 18-21 hr. Thus, cel displayed a threshold temperature or "break point" for the temperature compensation of its rhythm. Supplementation of cel strains, which require fatty acids, with unsaturated or short-chain fatty acids raised the threshold temperature to 26 degrees C, whereas supplementation with long-chain saturated fatty acids lowered it to 18 degrees C. These data suggest a role for fatty acids, as liquid components or as cellular metabolites, in the mechanism of temperature compensation.     

The job market in diagnostic radiology 1999: updated findings from a help wanted index of job advertisements

OBJECTIVE. The purpose of this article is to report 1999 data on the job market in diagnostic radiology detected using a help wanted index of job advertisements and to profile trends in practice type, location, and subspecialty using our previously published data as a basis for comparison. MATERIALS AND METHODS. Each advertised job for a diagnostic radiologist in the American Journal of Roentgenology and RADIOLOGY: between January 1991 and December 1999 was coded by practice type, location, and subspecialty. RESULTS. In 1999, 3926 positions were advertised for diagnostic radiologists, representing a 75% increase from 1998. Private practice jobs, which represented 53% of advertisements from 1991 through 1994 and 64% of ads from 1995 through 1998, increased to 66% of ads in 1999. Geographic trends in 1999 were characterized by a relative increase of jobs in the Midwest and California and a decrease in percentage (but increase in total number of ads) in the Northeast and Southwest. The demand for subspecialists continued in 1999, with only 34% of ads placed for general radiologists. A relative increase in demand for neuroradiologists, mammographers, and abdominal imagers was also seen in 1999 in comparison with previously published data from 1995 through 1998. CONCLUSION. The demand for diagnostic radiologists continues to rise, with more ads placed in 1999 than any other year from 1991 through 1998. Using a help wanted index of job advertisements, we have created an indicator of changes in the diagnostic radiology job market with specific reference to practice type, geographic location, and subspecialty training.     

Exploring frontal asymmetry using functional near-infrared spectroscopy: a preliminary study of the effects of social anxiety during interaction and performance tasks

Preliminary studies examining brain function associated with social anxiety suggest the possibility of right-sided prefrontal activation associated with phobic stimulation. Although most existing neuroimaging techniques preclude participants from engaging in ecologically valid social tasks during assessment, functional near-infrared spectroscopy (fNIRS) is a promising new technique that permits such assessment. The present study investigated the utility of the fNIRS procedure and explored frontal asymmetry during in vivo social challenge tasks among female undergraduate students who scored in top and bottom percentiles on a social anxiety screening measure. Results revealed that participants in both groups experienced a significant increase in concentration of blood volume and oxygenated hemoglobin in the right hemisphere compared to the left hemisphere while giving a speech. Non-hemispheric effects were also observed. In addition, the high anxiety group showed a non-significant trend toward greater right frontal activity than the low anxiety group. This study highlights the utility of the fNIRS device in successfully assessing real-time changes in cerebrovascular response as a function of naturalistic social behavior, and supports the potential utility of this technology in the study of the neurophysiology of social anxiety.     

Live birth after blastocyst transfer following only 2 days of progesterone administration in an agonadal oocyte recipient

In oocyte donation cycles where hormone replacement is given to recipients, progesterone administration is necessary to induce the luteal phase and synchronize the endometrium with the embryo stage. Most studies suggest that 5–7 days of progesterone are needed to prepare the endometrium for a day-5 embryo transfer and provide optimal implantation rate. This paper reports a case where an agonadal oocyte recipient received only 2 days of progesterone prior to the embryo transfer of a day-5 embryo. She subsequently had a clinical pregnancy and a live birth.     

Tricuspid regurgitant jet velocity and myocardial tissue Doppler parameters predict mortality in a cohort of patients with sickle cell disease spanning from pediatric to adult age groups ‐ revisiting this controversial concept after 16 years of additional evidence

Sickle cell disease (SCD) is a monogenic hemoglobinopathy associated with significant morbidity and mortality. Cardiopulmonary, vascular and sudden death are the reasons for the majority of young adult mortality in SCD. To better understand the clinical importance of multi‐level vascular dysfunction, in 2009 we assessed cardiac function including tricuspid regurgitant jet velocity (TRV), tissue velocity in systole(S′) and diastole (E′), inflammatory, rheologic and hemolytic biomarkers as predictors of mortality in patients with SCD. With up to 9 years of follow up, we determined survival in 95 children, adolescents and adults with SCD. Thirty‐eight patients (40%) were less than 21 years old at initial evaluation. Survival and Cox proportional‐hazards analysis were performed. There was 19% mortality in our cohort, with median age at death of 35 years. In the pediatric subset, there was 11% mortality during the follow up period. The causes of death included cardiovascular and pulmonary complications in addition to other end‐organ failure. On Cox proportional‐hazards analysis, our model predicts that a 0.1 m/s increase in TRV increases risk of mortality 3%, 1 cm/s increase in S′ results in a 91% increase, and 1 cm/s decrease in E′ results in a 43% increase in mortality. While excluding cardiac parameters, higher plasma free hemoglobin was significantly associated with risk of mortality (p=.049). In conclusion, elevated TRV and altered markers of cardiac systolic and diastolic function predict mortality in a cohort of adolescents and young adult patients with SCD. These predictors should be considered when counseling cardiovascular risk and therapeutic optimization at transition to adult providers.