CONTEXT Chronic otitis media with effusion (OME) has long been considered to
be a sterile inflammatory process. The previous application of molecular diagnostic
technologies to OME suggests that ...viable bacteria are present in complex communities
known as mucosal biofilms; however, direct imaging evidence of mucosal biofilms
associated with OM is lacking. OBJECTIVE To determine whether biofilm formation occurs in middle-ear mucosa in
an experimental model of otitis media. DESIGN AND MATERIALS A total of 48 research-grade, young adult chinchillas weighing 500 g
were used for 2 series of animal experiments: one to obtain specimens for
scanning electron microscopy and the other to obtain specimens for confocal
laser scanning microscopy using vital dyes. In each series, 21 animals were
bilaterally injected with viable Haemophilus influenzae bacteria and 1 was inoculated to account for expected mortality. Three
served as negative controls. Effusions and mucosal specimens were collected
from 2 infected animals that were euthanized at 3, 6, 12, and 24 hours and
at days 2, 4, 5, 10, 16, and 22 after inoculation. MAIN OUTCOME MEASURES Images were analyzed for biofilm morphology, including presence of microcolony
formation and for presence of bacteria on tissue surfaces. RESULTS Scanning electron microscopy demonstrated that biofilm formation was
evident in all specimens from animals beginning 1 day after infection and
was present through 21 days. Confocal laser scanning microscopy indicated
that bacteria within the biofilms are viable. CONCLUSION These preliminary findings provide evidence that mucosal biofilms form
in an experimental model of otitis media and suggest that biofilm formation
may be an important factor in the pathogenesis of chronic otitis media with
effusion.
Key points
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The amygdala mediates emotional processing, in particular fear learning, and disruption of its function is thought to contribute to the developmental origins of psychiatric disorders ...like depression, anxiety and autism spectrum disorders.
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It is difficult to identify the causes of these disorders or provide effective intervention because most of what is known of amygdala physiology is based on the adult.
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Using the whole‐cell patch clamp technique, we show that neurons in the developing rat amygdala undergo drastic changes to their electrophysiology, including passive membrane properties, intrinsic currents and resonance.
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This provides the first evidence that amygdala neuron physiology is dynamic before adulthood, and likely to contribute to emotional development.
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The results help us better understand the normative development of emotional processing and identify critical periods of maturation that may be sensitive to insult.
The basolateral amygdala (BLA) is critically involved in the pathophysiology of psychiatric disorders, which often emerge during brain development. Several studies have characterized postnatal changes to the morphology and biochemistry of BLA neurons, and many more have identified sensitive periods of emotional maturation. However, it is impossible to determine how BLA development contributes to emotional development or the aetiology of psychiatric disorders because no study has characterized the physiological maturation of BLA neurons. We addressed this critical knowledge gap for the first time using whole‐cell patch clamp recording in rat BLA principal neurons to measure electrophysiological properties at postnatal day (P)7, P10, P14, P21, P28 and after P35. We show that intrinsic properties of these neurons undergo significant transitions before P21 and reach maturity around P28. Specifically, we observed significant reductions in input resistance and membrane time constant of nearly 10‐ and 4‐fold, respectively, from P7 to P28. The frequency selectivity of these neurons to input also changed significantly, with peak resonance frequency increasing from 1.0 Hz at P7 to 5.7 Hz at P28. In the same period, maximal firing frequency significantly increased and doublets and triplets of action potentials emerged. Concomitantly, individual action potentials became significantly faster, firing threshold hyperpolarized 6.7 mV, the medium AHP became faster and shallower, and a fast AHP emerged. These results demonstrate neurons of the BLA undergo vast change throughout postnatal development, and studies of emotional development and treatments for juvenile psychiatric disorders should consider the dynamic physiology of the immature BLA.
Hereditary pancreatitis (HP) is a rare, early-onset genetic disorder characterized by epigastric pain and often more serious complications. We now report that an Arg-His substitution at residue 117 ...of the cationic trypsinogen gene is associated with the HP phenotype. This mutation was observed in all HP affected individuals and obligate carriers from five kindreds, but not in individuals who married into the families nor in 140 unrelated individuals. X-ray crystal structure analysis, molecular modelling, and protein digest data indicate that the Arg 117 residue is a trypsin-sensitive site. Cleavage at this site is probably part of a fail-safe mechanism by which trypsin, which is activated within the pancreas, may be inactivated; loss of this cleavage site would permit autodigestion resulting in pancreatitis.
SETTING: A high tuberculosis (TB) burden area in South Africa (notification rate for all TB cases 1400 per 100 000 population).OBJECTIVE: To determine the prevalence of and predictive factors ...associated with latent TB infection in adolescents.DESIGN: Adolescents aged
12-18 years were recruited from high schools, clinical and demographic data were collected, and a tuberculin skin test (TST) and a QuantiFERON®-TB Gold In-Tube (QFT) assay performed.RESULTS: A total of 6363 (58.2%) of 10 942 adolescents at the schools were enrolled. After
exclusions, of 5244 participants, 55.2% (95%CI 53.8-56.5) had TST ≥ 5 mm, while 50.9% (49.5-52.2) were QFT-positive. On multivariate analysis, Black/mixed race racial groups, male sex, older age, household TB contact, low income and low education level were predictive factors
for both TST- and QFT-positive results.CONCLUSION: About half of the adolescents were found to be latently infected with TB in a high TB burden area with demographic and poverty-related socio-economic factors predicting the risk of TB infection. Adolescents from deprived communities should
be considered an important target group for educational interventions by TB control programmes in high-burden settings.
Proneurogenic compounds have recently shown promise in some mouse models of Alzheimer's pathology. Antagonists at Group II metabotropic glutamate receptors (Group II mGluR: mGlu2, mGlu3) are reported ...to stimulate neurogenesis. Agonists at those receptors trigger γ-secretase-inhibitor-sensitive biogenesis of Aβ42 peptides from isolated synaptic terminals, which is selectively suppressed by antagonist pretreatment. We have assessed the therapeutic potential of chronic pharmacological inhibition of Group II mGluR in Dutch APP (Alzheimer's amyloid precursor protein E693Q) transgenic mice that accumulate Dutch amyloid-β (Aβ) oligomers but never develop Aβ plaques. BCI-838 is a clinically well-tolerated, orally bioavailable, investigational prodrug that delivers to the brain BCI-632, the active Group II mGluR antagonist metabolite. Dutch Aβ-oligomer-forming APP transgenic mice (APP E693Q) were dosed with BCI-838 for 3 months. Chronic treatment with BCI-838 was associated with reversal of transgene-related amnestic behavior, reduction in anxiety, reduction in levels of brain Aβ monomers and oligomers, and stimulation of hippocampal neurogenesis. Group II mGluR inhibition may offer a unique package of relevant properties as an Alzheimer's disease therapeutic or prophylactic by providing both attenuation of neuropathology and stimulation of repair.
Tightly regulated Ca2+ homeostasis is a prerequisite for proper cardiac function. To dissect the regulatory network of cardiac Ca2+ handling, we performed a chemical suppressor screen on zebrafish ...tremblor embryos, which suffer from Ca2+ extrusion defects. Efsevin was identified based on its potent activity to restore coordinated contractions in tremblor. We show that efsevin binds to VDAC2, potentiates mitochondrial Ca2+ uptake and accelerates the transfer of Ca2+ from intracellular stores into mitochondria. In cardiomyocytes, efsevin restricts the temporal and spatial boundaries of Ca2+ sparks and thereby inhibits Ca2+ overload-induced erratic Ca2+ waves and irregular contractions. We further show that overexpression of VDAC2 recapitulates the suppressive effect of efsevin on tremblor embryos whereas VDAC2 deficiency attenuates efsevin's rescue effect and that VDAC2 functions synergistically with MCU to suppress cardiac fibrillation in tremblor. Together, these findings demonstrate a critical modulatory role for VDAC2-dependent mitochondrial Ca2+ uptake in the regulation of cardiac rhythmicity.
The heart is a large muscle that pumps blood around the body by maintaining a regular rhythm of contraction and relaxation. If the heart loses this regular rhythm it works less efficiently, which can lead to life-threatening conditions.
Regular heart rhythms are maintained by changes in the concentration of calcium ions in the cytoplasm of the heart muscle cells. These changes are synchronised so that the heart cells contract in a controlled manner. In each cell, a contraction begins when calcium ions from outside the cell enter the cytoplasm by passing through a channel protein in the membrane that surrounds the cell. This triggers the release of even more calcium ions into the cytoplasm from stores within the cell. For the cells to relax, the calcium ions must then be pumped out of the cytoplasm to lower the calcium ion concentration back to the original level.
Shimizu et al. studied a zebrafish mutant—called tremblor—that has irregular heart rhythms because its heart muscle cells are unable to efficiently remove calcium ions from the cytoplasm. Embryos of the tremblor mutant were treated with a wide variety of chemical compounds with the aim of finding some that could correct the heart defect.
A compound called efsevin restores regular heart rhythms in tremblor mutants. Efsevin binds to a pump protein called VDAC2, which is found in compartments called mitochondria within the cell. Although mitochondria are best known for their role in supplying energy for the cell, they also act as internal stores for calcium. By binding to VDAC2, efsevin increases the rate at which calcium ions are pumped from the cytoplasm into the mitochondria. This restores rhythmic calcium ion cycling in the cytoplasm and enables the heart muscle cells to develop regular rhythms of contraction and relaxation. Increasing the levels of VDAC2 or another similar calcium ion pump protein in the heart cells can also restore a regular heart rhythm.
Efsevin can also correct irregular heart rhythms in human and mouse heart muscle cells, therefore the new role for mitochondria in controlling heart rhythms found by Shimizu et al. appears to be shared in other animals. The experiments have also identified the VDAC family of proteins as potential new targets for drug therapies to treat people with irregular heart rhythms.
Abstract Objective Multiple sclerosis (MS) is a disabling idiopathic inflammatory disorder with evidence of immune dysfunction. Current therapies for MS include preparations of β-interferon (βIFN). ...We studied the gene expression patterns in peripheral blood mononuclear cells from relapsing–remitting MS patients undergoing weekly βIFN-1a therapy (Avonex™; 30 mg intramuscular) to identify biomarkers for βIFN responsiveness. Methods Oligonucleotide microarrays were used for the comparative analysis of gene expression patterns from longitudinal PBMC samples taken from five patients undergoing βIFN therapy. Results On the basis of two-fold changes in expression levels and statistical analyses we selected a candidate diagnostic set of 136 genes that were differentially expressed between pretreatment and IFN-β-1a-treated MS patients. When we applied this gene set to cluster the specimens according to their expression profiles, the pretreatment samples clustered in one branch, and acute and chronic samples following treatment clustered in another branch. However, the chronic samples from the single clinical non-responder clustered with the pretreatment branch, suggesting that a possible reversal of βIFN-induced gene expression may be contributing to the poor clinical response. Conclusions These 136 genes represent potential targets for new MS therapeutics and the basis for lack of βIFN response.
Numerous studies have demonstrated that peptide modified surfaces influence short- and long-term cell responses such as attachment, shape and function in vitro. These responses are mediated via cell ...receptors known as integrins which bind specifically to short peptide sequences from larger proteins. Integrins transduce information to the nucleus through several cytoplasmic signalling pathways. Little is known, however, about the ability of peptide-coated surfaces to influence cell responses in vivo. The present study was designed to evaluate the quality and quantity of the new bone formed in response to titanium rods surface-coated with the peptide sequence Arg–Gly–Asp–Cys (RGDC) using gold-thiol chemistry and implanted in rat femurs. Histomorphometric analysis of cross-sections perpendicular to the implant long axis showed a significantly thicker shell of new bone formed around RGD-modified versus plain implants at 2 weeks (26.2±1.9 vs. 20.5±2.9
μm;
P<0.01). A significant increase in bone thickness for RGD implants was also observed at 4 weeks while bone surrounding controls did not change significantly in thickness (32.7±4.6 vs. 22.6±4.0
μm;
P<0.02). Mechanical pull-out testing conducted at 4 weeks revealed the average interfacial shear strength of peptide modified rods was 38% greater than control rods although this difference was not statistically significant. These pilot data suggest that an RGDC peptide coating may enhance titanium rod osseointegration in the rat femur. Long-term studies and evaluation of other peptides in larger animal models are warranted.
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