Aminopeptidase-A. I. CDNA cloning and expression and localization in rat tissues

Aminopeptidase-A (APA) is an ectoenzyme that selectively hydrolyzes acidic residues from the amino terminus of oligopeptides, including biologically active [Asp(1)]ANG II and [Asp(1)]CCK-8. We sought to characterize rat APA by cDNA cloning and expression and to determine its tissue distribution by in situ hybridization and immunohistochemistry. Sequence analysis of overlapping cDNA clones isolated from rat kidney cDNA libraries indicated that the full-length cDNA encoded a 945-amino acid protein with a predicted molecular mass of 108 kDa; the size was confirmed by in vitro translation of a full-length cDNA construct. Transient transfection of the full-length cDNA construct in mammalian cells yielded a protein approximately 140 kDa in size, a size that agrees with the immunoblots of APA from rat tissue and is consistent with APA being known as a glycosylated protein. Tissue APA activity and mRNA expression were highest in the kidney and ileum. Localization of APA by in situ hybridization and immunohistochemistry indicated that, with the exception of the kidney and ileum, where APA was localized to the luminal brush border of proximal tubules and enterocytes, respectively, APA was associated with either capillaries or the lining of sinusoids. Areas known to be physiological targets for ANG II, including glomeruli, the zona glomerulosa, and anterior pituitary, had high levels of APA. The localization pattern suggests that APA may subserve multiple functions, i.e., a generalized role in peptide scavenging and perhaps a more specific role in metabolism of circulating or locally produced ANG II or CCK-8.     

Activation of mutagens in cooked ground beef by human-liver microsomes

The total organic base fraction purified from fried ground beef is metabolized by human-liver microsomes to form mutagens detectable by the Ames/Salmonella bacterial assay. The mutagens produced have an absolute requirement for metabolic activation; without it, no increase in the number of revertants over background is seen. Microsomes from human liver activate the mutagens significantly more than microsomes from uninduced mouse or rat liver; the microsomes from one individual were nearly as active as those of Aroclor-induced mice and rats. alpha-Naphthoflavone (ANF) inhibits activation of these mutagenic bases, implying that the metabolism is mediated by the inducible form(s) of cytochrome P-448. Thus, the human liver has the potential to metabolize the cooked beef mutagen(s) to active intermediates, posing a possible mutagenic risk. However, unlike the animal metabolizing system, which needs to be artificially induced, the human system appears to be naturally induced through diet or environmental exposure.     

Development of photochemical method for meniscal repair: a preliminary study

Visible light combined with naphthalimides has previously been shown to catalyze formation of physical bonds in avascular meniscal tissue. The first objective was to modify the existing in vitro testing method (i.e., adhesion testing using lap-jointed slices) to gain more sensitivity in detecting relative bonding strengths among candidate bonding agents. A repeated measures experimental design (RMED) was used to account for variability in properties among bovine menisci and was achieved by testing all treatments/controls on slices from each meniscus. Additionally, to make the method more clinically relevant in modeling a bucket-handle tear, the bovine meniscal slices were cut with collagen fibers parallel to the test slice's length. Peak stress was greater for the complete treatment group (light plus naphthalimide) than for the control or incomplete treatment groups (light only or napthalimide only). The second objective was to perform concentration and photoactivation time dose-response studies. In the concentration dose-response study, peak stress was greater for all treatments when compared with the control but not different among treatment groups; however, there was a trend of increased bonding strength with increased concentration. In the photoactivation time dose-response study, peak stress was greater for all treatments when compared with the control and greater for the 3-min treatment vs. the 6- and 9-min treatments. Peak stress was not different between the longer treatments. The RMED provided increased reproducibility and statistical sensitivity for detecting differences among treatments and will be used to test candidate bonding agents prior to in vivo testing.     

Impedimetric immunosensor for the specific label free detection of ciprofloxacin antibiotic

Impedance spectroscopy approaches combined with the immunosensor technology have been used for the determination of trace amounts of ciprofloxacin antibiotic belonging to the fluoroquinolone family. The sensor electrode was based on the immobilization of anti-ciprofloxacin antibodies by chemical binding onto a poly(pyrrole-NHS) film electrogenerated on a solid gold substrate. The electrode surface was modified by electropolymerization of pyrrole-NHS, antibody grafting and ciprofloxacin immunoreaction. The sensitive steps of surface modification, cyclic voltammetry (CV) and atomic force microscopy (AFM) imaging have been used for electrode surface characterization. The immunoreaction of ciprofloxacin on the grafted anti-ciprofloxacin antibody directly triggers a signal via impedance spectroscopy measurements which allows the detection of extremely low concentration of 10 pg/ml ciprofloxacin.     

Focus: Addiction: A Feasibility Study of Bilateral Anodal Stimulation of the Prefrontal Cortex Using High-Definition Electrodes in Healthy Participants

Transcranial direct current stimulation (tDCS) studies often use one anode to increase cortical excitability in one hemisphere. However, mental processes may involve cortical regions in both hemispheres. This study’s aim was to assess the safety and possible effects on affect and working memory of tDCS using two anodes for bifrontal stimulation. A group of healthy subjects participated in two bifrontal tDCS sessions on two different days, one for real and the other for sham stimulation. They performed a working memory task and reported their affect immediately before and after each tDCS session. Relative to sham, real bifrontal stimulation did not induce significant adverse effects, reduced decrement in vigor-activity during the study session, and did not improve working memory. These preliminary findings suggest that bifrontal anodal stimulation is feasible and safe and may reduce task-related fatigue in healthy participants. Its effects on neuropsychiatric patients deserve further study.     

Characterization of compost produced from separated pig manure and a variety of bulking agents at low initial C/N ratios

The aim of this study was to investigate the composting of separated pig manure solids with or without a variety of bulking agents at a low initial C/N ratio (12.5-23.3). Compost stability was investigated using an oxygen uptake rate (OUR) test and compost maturity was investigated using a germination index test. All treatments showed typical patterns of compost temperature. Temperatures above 60 °C were achieved by Day 2, followed by a thermophilic phase (50-60 °C), which lasted for 1 to 2 weeks followed by a cooling phase. The stability of one of treatments which did not contain any bulking agent - OUR of 25 mmol O₂ kg⁻¹ OM hour⁻¹ - was negatively affected by its initial high water content (69%). The addition of a bulking agent and initial water content below 60% were necessary to compost the separated solid fraction of pig manure at a low initial C/N ratio.