Dynamic associations between glucose and ecological momentary cognition in Type 1 Diabetes.

Type 1 diabetes (T1D) is a chronic condition characterized by glucose fluctuations. Laboratory studies suggest that cognition is reduced when glucose is very low (hypoglycemia) and very high (hyperglycemia). Until recently, technological limitations prevented researchers from understanding how naturally-occurring glucose fluctuations impact cognitive fluctuations. This study leveraged advances in continuous glucose monitoring (CGM) and cognitive ecological momentary assessment (EMA) to characterize dynamic, within-person associations between glucose and cognition in naturalistic environments. Using CGM and EMA, we obtained intensive longitudinal measurements of glucose and cognition (processing speed, sustained attention) in 200 adults with T1D. First, we used hierarchical Bayesian modeling to estimate dynamic, within-person associations between glucose and cognition. Consistent with laboratory studies, we hypothesized that cognitive performance would be reduced at low and high glucose, reflecting cognitive vulnerability to glucose fluctuations. Second, we used data-driven lasso regression to identify clinical characteristics that predicted individual differences in cognitive vulnerability to glucose fluctuations. Large glucose fluctuations were associated with slower and less accurate processing speed, although slight glucose elevations (relative to person-level means) were associated with faster processing speed. Glucose fluctuations were not related to sustained attention. Seven clinical characteristics predicted individual differences in cognitive vulnerability to glucose fluctuations: age, time in hypoglycemia, lifetime severe hypoglycemic events, microvascular complications, glucose variability, fatigue, and neck circumference. Results establish the impact of glucose on processing speed in naturalistic environments, suggest that minimizing glucose fluctuations is important for optimizing processing speed, and identify several clinical characteristics that may exacerbate cognitive vulnerability to glucose fluctuations.

A kilonova as the electromagnetic counterpart to a gravitational-wave source.

Gravitational waves were discovered with the detection of binary black-hole mergers and they should also be detectable from lower-mass neutron-star mergers. These are predicted to eject material rich in heavy radioactive isotopes that can power an electromagnetic signal. This signal is luminous at optical and infrared wavelengths and is called a kilonova. The gravitational-wave source GW170817 arose from a binary neutron-star merger in the nearby Universe with a relatively well confined sky position and distance estimate. Here we report observations and physical modelling of a rapidly fading electromagnetic transient in the galaxy NGC 4993, which is spatially coincident with GW170817 and with a weak, short γ-ray burst. The transient has physical parameters that broadly match the theoretical predictions of blue kilonovae from neutron-star mergers. The emitted electromagnetic radiation can be explained with an ejected mass of 0.04 ± 0.01 solar masses, with an opacity of less than 0.5 square centimetres per gram, at a velocity of 0.2 ± 0.1 times light speed. The power source is constrained to have a power-law slope of -1.2 ± 0.3, consistent with radioactive powering from r-process nuclides. (The r-process is a series of neutron capture reactions that synthesise many of the elements heavier than iron.) We identify line features in the spectra that are consistent with light r-process elements (atomic masses of 90-140). As it fades, the transient rapidly becomes red, and a higher-opacity, lanthanide-rich ejecta component may contribute to the emission. This indicates that neutron-star mergers produce gravitational waves and radioactively powered kilonovae, and are a nucleosynthetic source of the r-process elements.

Discovery and spectroscopy of the young jovian planet 51 Eri b with the Gemini Planet Imager.

Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10(-6) and an effective temperature of 600 to 750 kelvin. For this age and luminosity, "hot-start" formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the "cold-start" core-accretion process that may have formed Jupiter.

Computerized mental health risk appraisal for college students: user acceptability and correlation with standard pencil-and-paper questionnaires.

Due to an interaction of age, birth cohort, genetics, and the lifestyle factors inherent in the "college experience," some college students are at increased risk for mental health problems such as alcohol, tobacco, and other drug abuse; depression; stress and anxiety; and eating disorders. A program to promote self-monitoring of students' health behaviors could prove beneficial to their future well-being and potentially reduce overall medical costs for this group. Computerized mental health risk appraisals, if valid, reliable, and acceptable to students and administrators, could facilitate implementation and minimize the costs of such a program. This pilot study was designed to determine whether a confidential computer-based risk appraisal is a valid and acceptable measure of current mental health status in a university student sample. Two basic questions were addressed. First, do computerized questionnaires yield results similar to their pencil-and-paper counterparts? Second, how do students rate and compare the two formats?

Regulation of acetylcholinesterase forms in quail and chicken muscle cultures.

High molecular forms of acetylcholinesterase (AChE) have been difficult to obtain in primary cultures of muscle from mammals and birds. This research used pectoral muscle cultures from Japanese quail and chick embryos grown in medium containing embryo extract and horse serum to study the growth and extraction conditions necessary for study of high molecular weight 20S AChE forms found in these birds. The results confirmed the presence of a 20S AChE form in quail muscle cultures and showed that its extraction from the cells was considerably improved by using a Mg-cholate extraction buffer rather than the more commonly used NaCl-Triton X buffer. A striking finding was that removal of serum from the medium for 1-2 days caused the preferential increase in a 20S form in the quail and the resolution of one from background activity in chick muscle cultures. Removal of embryo extract had no effect on levels of the AChE forms. The results suggest that serum factors inhibit the formation of the high molecular weight, motor end plate associated form of AChE in aneural cultures of avian muscle, and that effects of factors such as neural extracts and nerves on AChE forms in cultured muscle should be examined using a defined basal media.

Allosteric interactions between the membrane-bound acetylcholine receptor and chemical mediators. Kinetic studies.

The kinetics of the specific irreversible reaction of a snake neurotoxin, alpha-bungarotoxin, with the acetylcholine receptor of electroplax membrane preparations have been investigated. The effects of activators (decamethonium, carbamylcholine) and inhibitors (alpha-bungarotoxin, d-tubocurarine) of neural transmission on this reaction have been measured and the following new information obtained. (1) The irreversible reaction is preceded by the reversible formation of toxin-receptor complexes. (2) Two types of receptor binding site exist. d-Tubocurarine directly competes with the toxin for one type of binding site. Decamethonium and carbamylcholine are noncompetitive inhibitors of the toxin reaction. (3) The data are inconsistent with binding sites on separate and distinct molecules or with preexisting nonequivalent binding sites. A simple model is proposed to explain both the kinetic data and equilibrium measurements which indicated that activators and inhibitors of neural transmission compete for only one-half of the receptor sites available to them. The model proposes that for the compounds investigated the binding sites of activators do not overlap with those of inhibitors and the ligand-induced conformational changes of the receptor result in changes in the affinities of the binding sites. The model is simple and is based on mechanisms which have been found to be valid for many well-characterized regulatory enzymes.