Optimal Calibration of PET Crystal Position Maps Using Gaussian Mixture Models

A method is developed for estimating optimal PET gamma-ray detector crystal position maps, for arbitrary crystal configurations, based on a binomial distribution model for scintillation photon arrival. The approach is based on maximum likelihood estimation of Gaussian mixture model parameters using crystal position histogram data, with determination of the position map taken from the posterior probability boundaries between mixtures. This leads to minimum probability of error crystal identification under the assumed model

Diet-induced obesity impairs mammary development and lactogenesis in murine mammary gland

We have developed a mouse model of diet-induced obesity that shows numerous abnormalities relating to mammary gland function. Animals ate 40% more calories when offered a high-fat diet and gained weight at three times the rate of controls. They exhibited reduced conception rates, increased peripartum pup mortality, and impaired lactogenesis. The impairment of lactogenesis involved lipid accumulation in the secretory epithelial cells indicative of an absence of copius milk secretion. Expression of mRNAs for -casein, whey acid protein, and -lactalbumin were all decreased immediately postpartum but recovered as lactation was established over 2–3 days. Expression of acetyl-CoA carboxylase (ACC)- mRNA was also decreased at parturition as was the total enzyme activity, although there was a compensatory increase in the proportion in the active state. By day 10 of lactation, the proportion of ACC in the active state was also decreased in obese animals, indicative of suppression of de novo fatty acid synthesis resulting from the supply of preformed fatty acids in the diet. Although obese animals consumed more calories in the nonpregnant and early pregnant states, they showed a marked depression in fat intake around day 9 of pregnancy before food intake recovered in later pregnancy. Food intake increased dramatically in both lean and obese animals during lactation although total calories consumed were identical in both groups. Thus, despite access to high-energy diets, the obese animals mobilized even more adipose tissue during lactation than their lean counterparts. Obese animals also exhibited marked abnormalities in alveolar development of the mammary gland, which may partially explain the delay in differentiation evident during lactogenesis

Elevated Troponin and Jarisch-Herxheimer Reaction in Tick-Borne Relapsing Fever: A Case Report

We describe a patient with fever and borreliosis in the Northwestern Washington State, USA. The patient exhibited a classic Jarisch-Herxheimer reaction of tachycardia, hypotension, and thrombocytopenia following antimicrobial therapy, and she also developed an elevated serum cardiac troponin during therapy

Reproductive Biology of Middle Mississippi River Shovelnose Sturgeon: Insights from Seasonal and Age Variation in Plasma Sex Steroid and Calcium Concentrations

Shovelnose sturgeon Scaphirhynchus platorynchus are endemic to the Mississippi River drainage and are commercially harvested for roe in several states. Status of shovelnose sturgeon populations throughout much of its range is unknown or declining; Mississippi River stocks are experiencing recruitment overfishing and may be at risk of collapse. Restoration of shovelnose sturgeon populations will require additional information on their reproductive biology, including age at maturity and reproductive status and cycles. The objectives of this study were to determine the effects of reproductive stage, fish age, and season on plasma 17-β estradiol (E2) and calcium (Ca2+) concentrations in female shovelnose sturgeon and plasma testosterone (T) concentrations in male shovelnose sturgeon from the middle Mississippi River (MMR). We also assessed the relationship between plasma vitellogenin (VTG) and Ca2+ concentrations for female shovelnose sturgeon. Plasma E2 and Ca2+ concentrations in females and T concentrations in males differed among reproductive stages, consistent with results of prior research on shovelnose sturgeon and other sturgeon species. VTG and Ca2+ concentrations were strongly correlated in female shovelnose sturgeon, indicating that Ca2+ can be used as a surrogate for VTG assays for identification of vitellogenic females, as has been shown for other sturgeon species. Age at maturity was estimated at 10 years for males and 9 years for females based on T and E2 profiles, consistent with other recent age at maturity estimates in the MMR and Wabash River determined by gonadal examination. Peaks in plasma sex steroid and Ca2+ concentrations during April and October possibly reflected the spring spawning season and provide additional evidence in support of recent documentation of fall spawning by shovelnose sturgeon in the MMR. Additional research is needed to elucidate fall spawning by shovelnose sturgeon in the MMR