Development of an apical plasma membrane domain and tight junctions during histogenesis of the mammalian pancreas

The role of tight junctions (zonula occludens) in the formation of apical plasma membrane (PM) domains was investigated in the embryonic rat pancreas. In the present study, lectin-rhodamine (WGA-TRITC and RCAII-TRITC) and lectin-gold (WGA-Au and RCAII-Au) conjugates were used to monitor apical PM domain formation and freeze-fracture analysis was used to monitor tight junction formation in the pancreatic epithelium of embryonic, neonatal, and adult rats. Fluorescent and TEM analysis of WGA and RCAII binding indicated that an apical PM domain is formed as early as Day 13 of gestation in the pancreatic epithelium. While apical WGA binding remained into adult life, RCAII binding was lost by 1 day after birth. In contrast, tight junctions were not observed until Day 14 of gestation. At this time, tight junctions were found to be incomplete in formation and typically consisted of linear arrays of IMPs or discontinuous arrays of sealing strands (focal adherens). Continuous tight junctions were not completely formed until Day 15 of gestation. Continued development of tight junctions during gestation was characterized by (1) an increase in the number of sealing strands and (2) a more parallel arrangement of sealing strands within each junctional complex. By 8 weeks after birth, tight junctions were more loosely organized and contained fewer sealing strands as compared to that observed in the fetus. These results suggest that lateral diffusion of apical PM glycoconjugates may be restricted even in the absence of complete tight junctional complexes during development of the rat pancreas.     

Haemolytic reaction of Listeria monocytogenes on bilayer Columbia Agar plates with defibrinated guinea-pig blood

Haemolysis on blood agar is an important test for the differentation of pathogenic from non-pathogenic Listeria species. The food-borne pathogen Listeria monocytogenes can only be differentiated from harmless L. innocua by its weak β-haemolysis on blood agar. This study demonstrates that L. monocytogenes , which is weakly haemolytic on sheep or horse blood agar forms clear zones of haemolysis on guinea-pig blood agar, which renders haemolysis enhancing methods, such as the CAMP test unnecessary.     

Extracellular matrix (mesoglea) of Hydra vulgaris. I. Isolation and characterization.

Hydrozoans such as Hydra vulgaris, as with all classes of Cnidaria, are characterized by having their body wall organized as an epithelial bilayer with an intervening acellular layer termed the mesoglea. The present study was undertaken to determine what extracellular matrix (ECM) components are associated with Hydra mesoglea. Using polyclonal antibodies generated from vertebrate ECM molecules, initial light and electron microscopic immunocytochemical studies indicated the presence of type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin immunoreactive components in Hydra mesoglea. These immunocytochemical observations were in part supported by biochemical analyses of isolated Hydra mesoglea which indicated the presence of fibronectin and laminin based on Western blot analysis. Amino acid analysis of total mesoglea and some of its isolated components confirmed the presence of collagen molecules in mesoglea. Additional studies indicated the presence of (1) a gelatin binding protein in Hydra which was immunoreactive with antibodies raised to human plasma fibronectin and (2) a noncollagen fragment extracted from mesoglea which was immunoreactive to antibodies raised to the NC1 domain (alpha 1 subunit) of bovine glomerular basement membrane type IV collagen. These observations indicate that Hydra mesoglea is evolutionarily a primitive basement membrane that has retained some properties of interstitial ECM.     

Why Do Medical Professional Regulators Dismiss Most Complaints From Members of the Public? Regulatory Illiteracy,Epistemic Injustice,and Symbolic Power

Drawing on an analysis of complaint files that we conducted for the Irish Medical Council (Madden and O’Donovan 2015), this paper offers three possible explanations for the gap between the ubiquity of official commitments to taking patients’ complaints seriously and medical professional regulators’ dismissal—as not warranting an inquiry—of the vast majority of complaints submitted by members of the public. One explanation points to the “regulatory illiteracy” of many complainants, where the remit and threshold of seriousness of regulators is poorly understood by the general public. Another points to possible processes of “institutional epistemic injustice” (Fricker 2007; Anderson 2012) that unjustly undermine the credibility of certain complainants, such as those with low levels of formal education. A third explanation highlights the marginalization of the general public from “symbolic power” (Bourdieu 1989) to define what matters in medical professional regulation. The paper is offered in a spirit of ideas in progress and raising questions rather than definitive insights into the regulatory process.     

Cellular Senescence Is Induced by the Environmental Neurotoxin Paraquat and Contributes to Neuropathology Linked to Parkinson’s Disease

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Ability of laboratory methods to predict in-use efficacy of antimicrobial preservatives in an experimental cosmetic

Volume 60, no. 12, p. 4553: a present address for S. J. Wells should be given, as follows: (dag) Present address: Cadbury Beverages North America, Trumbull, CT 06611. [This corrects the article on p. 4553 in vol. 60.].     

Interaction with Shelter Dogs Reduces Negative Affect of Adolescents in Substance Use Disorder Treatment

We investigated the effectiveness of a human–animal interaction program, involving dogs from an animal shelter, in improving affect of adolescent males in inpatient treatment for substance use disorder (SUD). We hypothesized that adolescents would experience improvements in affect and attitudes toward activities when participating in human–dog interaction activities (dog-interaction condition) compared with “treatment-as-is” recreational activities (control condition). Participants were assigned to weekly 1-h-long condition activities for 8 weeks (4 weeks per condition). Due to attrition, only the participants’ first and second exposures to each condition were evaluated. Using a withinand between-subjects, repeated measures crossover design, we assessed effects of the two conditions on affective states as indexed by Positive and Negative Affect Scale-Expanded Form (PANAS-X) subscales (mixed linear model, n = 12). Attitudes toward doginteraction and control activities were assessed using a researcher-generated survey (ordered logistic regression, n = 14, mean age = 16.2 years). Condition impacted Hostility (F_(1,31) = 6.55, p < 0.05) and Sadness (F_(1,41) = 4.62, p < 0.05) subscale scores; scores were higher following the control condition and lower following the dog-interaction condition. There was a carryover effect of condition in the previous activity session on Sadness scores during the current activity session (F_(1,41) = 4.32, p < 0.05), suggesting that the prior session experience affected current expectations. In the attitudes survey, the dog-interaction condition elicited more positive responses than the control condition (X² ≥ 4.10, df = 1, p < 0.05). From this exploratory study, we conclude that the dog-interaction activities induced an improvement in affect, specifically within dimensions of negative affect, and participants had a more favorable attitude toward the dog activities than the treatment-as-is activities. Offering activities involving interaction with shelter dogs thus shows promise as a useful method for restoring responsiveness to naturally reinforcing (non-substance-related) affective stimuli in adolescents with SUD.     

Characterization of implants from Dupuytren's contracture tissue into the nude (athymic) mouse

Dupuytren's contracture tissues were obtained from six patients as excess surgical material. Pieces of these tissues (a total of 38 implants) were placed into subcutaneous pockets in the suprascapular area of nude (athymic) mice. The objective was to determine whether the implant tissues would be maintained in the mouse with the characteristics of Dupuytren's tissue. The implants were removed for study at 14-179 days after implantation. Microvascular anastomosis between implant and host skin was established within the first 14 days. Histologic character and electron microscopic structure of the implants did not change during the course of the study. The implants became reduced in size with time. However, neither the spatial pattern of collagen nor the appearance of fibroblast cells changed. The original high levels of chondroitin-4-sulfate were significantly decreased in the 66- to 179-day postimplantation group, but were not significantly different from the values for normal fascial bands. The hyaluronic acid of the implants increased significantly with time of implantation, but never reached the level found in the normal fascial bands. The use of implants into nude mice may be useful for further experimental studies of Dupuytren's contracture.     

Truncation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from Rhodospirillum rubrum affects the holoenzyme assembly and activity.

Truncations of the subunit of ribulose bisphosphate carboxylase/oxygenase (Rubisco) from Rhodospirillum rubrum were generated by site-directed mutagenesis to examine the role of the C-terminal tail section. Removal of the last and the penultimate alpha-helices in the tail section changes the quaternary structure of the protein. Electrophoretic and electron microscope analysis revealed that the truncated subunits assemble into an octamer, whereas the wild-type enzyme has a dimeric structure. The octomerization of the mutant protein is due to a hydrophobic patch exposed to the solvent by truncation of the subunit. The mutant protein thus consists of four dimers, bound end-to-end by hydrophobic interactions. Insertion of a polar amino acid in the hydrophobic patch by a L424 to N424 substitution restores the familiar dimeric structure. Truncation of the subunit is associated with a considerable decrease in catalytic activity. The mutants undergo carbamylation but bind the reaction intermediate analog, 2-carboxy arabinitol-1,5-bisphosphate, poorly. This indicates that loss of activity in the mutant is due to weakened substrate binding. These findings suggest that the mutations in the tail section of the subunit are transmitted to the active site, although the C-terminal region is far from the active site. On the basis of the crystal structure of Rubisco, we propose a model for how the truncations of the enzyme subunit induce conformational changes in one of the two phosphate binding sites.