Molecular imaging of thin mammalian tissue sections by mass spectrometry

Imaging of tissue sections by mass spectrometry provides a detailed molecular picture containing information on both the abundance and distribution of many constituent compounds. Mass spectra are acquired directly from fresh frozen tissue sections using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS); sample preparation and data collection mode determine the spatial resolution or surface area of the section represented in each mass spectrum. Statistical analyses of the individual ion signatures yield biomarkers whose abundances correlate to cell development processes, tumorigenesis and/or drug treatment. In an alternate mode, the generation of intensity maps for individual ions provides a visual representation of the distribution of each species throughout the section at spatial resolutions as small as 50 microm. The availability of this molecular information is likely to be of great value to clinicians and should lead to improved therapeutic efficacy in the future.     

Repeated triggering of sporulation in Bacillus subtilis selects against a protein that affects the timing of cell division

Bacillus subtilis sporulation is a last-resort phenotypical adaptation in response to starvation. The regulatory network underlying this developmental pathway has been studied extensively. However, how sporulation initiation is concerted in relation to the environmental nutrient availability is poorly understood. In a fed-batch fermentation set-up, in which sporulation of ultraviolet (UV)-mutagenized B. subtilis is repeatedly triggered by periods of starvation, fitter strains with mutated tagE evolved. These mutants display altered timing of phenotypical differentiation. The substrate for the wall teichoic acid (WTA)-modifying enzyme TagE, UDP-glucose, has recently been shown to be an intracellular proxy for nutrient availability, and influences the timing of cell division. Here we suggest that UDP-glucose also influences timing of cellular differentiation.     

Chipping away at major depressive disorder

An intriguing recent study examines the role of miR-1202, a glutamate receptor regulating microRNA, in regulating major depressive disorder.     

Molecular docking analysis of flavonoids with aldose reductase

Diabetes mellitus is a group of metabolic disorders that has risen to become the third most common cause in humans in recent years. The development of new bioactive substances from natural sources is a relatively new area. Flavonoids are believed to have a variety of beneficial properties in nature, including anti-inflammatory, antimicrobial, anticancer, antioxidant, neuroprotective, and anti-HIV properties. 15 naturally occurring flavonoids docked with the selected target aldose reductase. We report the optimal binding of Acumitin, Agathisflavone, Agehoustin B, and alpha-Toxicarol with aldose reductase for further consideration in drug discovery for T2DM.     

Effects of intima stiffness and plaque morphology on peak cap stress

Background  

Rupture of the cap of a vulnerable plaque present in a coronary vessel may cause myocardial infarction and death. Cap rupture occurs when the peak cap stress exceeds the cap strength. The mechanical stress within a cap depends on the plaque morphology and the material characteristics of the plaque components. A parametric study was conducted to assess the effect of intima stiffness and plaque morphology on peak cap stress.     

Mental Health Diagnostic Frameworks,Imputed Causes of Mental Illness,and Alternative Treatments in Northern Tanzania: Exploring Mental Health Providers’ Perspectives

In Tanzania, a nation with a large mental health treatment gap, local stakeholders’ perspectives are critical for informing effective treatment. The practice-based perspectives of mental health providers may be particularly instructive. Existing foundational literature on the professional population in this region is scarce. We conducted semi-structured interviews with 29 mental health providers in northern Tanzania. Interviews focused on three topics: use of international diagnostic frameworks for mental illness, beliefs about causes of mental health concerns, and alternative treatments sought by clients. Interview data were coded and analyzed using consensual qualitative research and the constant comparative method. Usage of diagnostic frameworks varied widely. Providers believed frameworks accurately described many patients but neglected somatic symptoms and contained diagnoses that they had never witnessed. Providers described supernatural and spiritual attributions of mental illness as substantially impacting treatment decisions. Other notable attributions included physical illness, drug/alcohol use, and heredity. Providers reported their clients routinely sought treatment from traditional and spiritual healers prior to seeking care in the formal health system. This study builds a foundation for the ongoing development of the mental health system in northern Tanzania. Findings also support exploration of integrative models of care and task-shifting to incorporate traditional and spiritual beliefs.     

Higher‐order assemblies of oligomeric cargo receptor complexes form the membrane scaffold of the Cvt vesicle

Selective autophagy is the mechanism by which large cargos are specifically sequestered for degradation. The structural details of cargo and receptor assembly giving rise to autophagic vesicles remain to be elucidated. We utilize the yeast cytoplasm‐to‐vacuole targeting (Cvt) pathway, a prototype of selective autophagy, together with a multi‐scale analysis approach to study the molecular structure of Cvt vesicles. We report the oligomeric nature of the major Cvt cargo Ape1 with a combined 2.8 Å X‐ray and negative stain EM structure, as well as the secondary cargo Ams1 with a 6.3 Å cryo‐EM structure. We show that the major dodecameric cargo prApe1 exhibits a tendency to form higher‐order chain structures that are broken upon interaction with the receptor Atg19 in vitro. The stoichiometry of these cargo–receptor complexes is key to maintaining the size of the Cvt aggregate in vivo. Using correlative light and electron microscopy, we further visualize key stages of Cvt vesicle biogenesis. Our findings suggest that Atg19 interaction limits Ape1 aggregate size while serving as a vehicle for vacuolar delivery of tetrameric Ams1.     

Regulation of rat ovarian cell growth and steroid secretion

A cultured rat ovarian cell line (31 A-F(2)) was used to study the effect of growth factors (epidermal growth factor [EGF] and fibroblast growth factor [FGF]), a survival factor (ovarian growth factor [OGF]), a hormone (insulin), and an iron-binding protein (transferring) on cell proliferation and steroid production under defined culture conditions. EGF and insulin were shown to be mitogenic (half-maximal response at 0.12 nM and 0.11 muM, respectively) for 31A-F(2) cells incubated in serum-free medium. EGF induced up to three doublings in the cell population, whereas insulin induced an average of one cell population doubling. FGF, OGF, and transferrin were found not to have any prominent effect on cell division when incubated individually with 31A-F(2) cells in serum-free medium. However, a combination of EGF, OGF, insulin, and transferrin stimulated cell division to the same approximate extent as cells incubated in the presence of 5 percent fetal calf serum. EGF or insulin did not significantly affect total cell cholesterol levels (relative to cells incubated in serum-free medium) when incubated individually with 31A-F(2) cells. However, cell cholesterol levels were increased by the addition of OGF (250 percent), FGF (370 percent), or a combination of insulin and EGF (320 percent). Progesterone secretion from 31A-F(2) cells was enhanced by EGF (25 percent), FGF (80 percent), and insulin (115 percent). However, the addition of a mitogenic mixture of EGF, OGF, insulin, and transferrin suppressed progesterone secretion 150 percent) below that of control cultures. These studies have permitted us to determine that EGF and insulin are mitogenic factors that are required for the growth of 31A-F(2) cells and that OGF and transferrin are positive cofactors that enhance growth. Also, additional data suggest that cholesterol and progesterone production in 31A-F(2) cells can be regulated by peptide growth factors and the hormone insulin.     

9-AAP, a fluorescent beta-adrenergic antagonist, enters the hamster sperm acrosome in a manner inconsistent with binding to beta-adrenergic receptors

We have previously shown that the hamster sperm acrosome reaction, an event essential for fertilization, is stimulated by beta-adrenergic agonists and inhibited by beta-adrenergic antagonists. In the present report, we describe attempts to use (+/-)-9-aminoacridylpropranolol (9-AAP), a fluorescent derivative of a potent beta-adrenergic antagonist, to microscopically detect beta-adrenergic receptors on cauda epididymal hamster spermatozoa in vitro. 9-AAP binding to washed hamster spermatozoa was localized primarily in the acrosomal region, but we were unable to consistently displace the 9-AAP with the biologically active (-)-stereoisomers of several beta-adrenertic agonists and antagonists. Such displacement is necessary in order to separate binding to receptors from "nonspecific binding." Thus we did not detect sperm beta-adrenertic receptors by this method. Failure to detect the receptors with 9-AAP may be due to their presence in numbers too low for detection by this compound or to the masking of the receptors in these uncapacitated sperm. However, we could displace 9-AAP with either 5.0 mM NH4Cl or 1.2 microgram/ml nigericin, compounds capable of discharging pH gradients across cell membranes. These compounds have also been previously reported to displace the fluorescent portion of 9-AAP, 9-aminoacridine from the acrosome by such mechanism. The present results suggest that 9-AAP fluorescence does not always represent binding to beta-adrenergic receptors or "nonspecific binding," but may also represent the concentration of 9-AAP in acidic compartments within a cell.