Light sheet fluorescence microscopy of optically cleared brains for studying the glymphatic system

Fluid transport in the perivascular space by the glia-lymphatic (glymphatic) system is important for the removal of solutes from the brain parenchyma, including peptides such as amyloid-beta which are implicated in the pathogenesis of Alzheimer’s disease. The glymphatic system is highly active in the sleep state and under the influence of certain of anaesthetics, while it is suppressed in the awake state and by other anaesthetics. Here we investigated whether light sheet fluorescence microscopy of whole optically cleared murine brains was capable of detecting glymphatic differences in sleep- and awake-mimicking anaesthesia, respectively. Using light-sheet imaging of whole brains, we found anaesthetic-dependent cerebrospinal fluid (CSF) influx differences, including reduced tracer influx along tertiary branches of the middle cerebral artery and reduced influx along dorsal and anterior penetrating arterioles, in the awake-mimicking anaesthesia. This study establishes that light sheet microscopy of optically cleared brains is feasible for quantitative analyses and can provide images of the entire glymphatic system in whole brains.     

Photoperiod-induced neurotransmitter plasticity declines with aging: An epigenetic regulation?

Neuroplasticity has classically been understood to arise through changes in synaptic strength or synaptic connectivity. A newly discovered form of neuroplasticity, neurotransmitter switching, involves changes in neurotransmitter identity. Chronic exposure to different photoperiods alters the number of dopamine (tyrosine hydroxylase, TH+) and somatostatin (SST+) neurons in the paraventricular nucleus (PaVN) of the hypothalamus of adult rats and results in discrete behavioral changes. Here, we investigate whether photoperiod-induced neurotransmitter switching persists during aging and whether epigenetic mechanisms of histone acetylation and DNA methylation may contribute to this neurotransmitter plasticity. We show that this plasticity in rats is robust at 1 and at 3 months but reduced in TH+ neurons at 12 months and completely abolished in both TH+ and SST+ neurons by 18 months. De novo expression of DNMT3a catalyzing DNA methylation and anti-AcetylH3 assessing histone 3 acetylation were observed following short-day photoperiod exposure in both TH+ and SST+ neurons at 1 and 3 months while an overall increase in DNMT3a in SST+ neurons paralleled neuroplasticity reduction at 12 and 18 months. Histone acetylation increased in TH+ neurons and decreased in SST+ neurons following short-day exposure at 3 months while the total number of anti-AcetylH3+ PaVN neurons remained constant. Reciprocal histone acetylation in TH+ and SST+ neurons indicates the importance of studying epigenetic regulation at the circuit level for identified cell phenotypes. The findings may be useful for developing approaches for noninvasive treatment of disorders characterized by neurotransmitter dysfunction.     

Chronic subthreshold subdural cortical stimulation for the treatment of focal epilepsy originating from eloquent cortex

Medically refractory epilepsy remains a major medical problem worldwide. Although some patients are eligible for surgical resection of seizure foci, a proportion of patients are ineligible for a variety of reasons. One such reason is that the foci reside in eloquent cortex of the brain and therefore resection would result in significant morbidity. This retrospective study reports our experience with a novel neurostimulation technique for the treatment of these patients. We identified three patients who were ineligible for surgical resection of the intracranially identified seizure focus because it resided in eloquent cortex, who underwent therapeutic trial of focal cortical stimulation delivered through the subdural monitoring grid. All three patients had a significant reduction in seizures, and two went on to permanent implantation, which resulted in long‐term reduction in seizure frequency. In conclusion, this small case report provides some evidence of proof of concept of the role of targeted continuous neocortical neurostimulation in the treatment of medically refractory focal epilepsy, and provides support for ongoing investigations into this treatment modality. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here .     

Transepithelial dipeptide (glycylsarcosine) transport across epithelial monolayers of human Caco-2 cells is rheogenic

Net transepithelial transport (and cellular accumulation) of the dipeptide glycylsarcosine (Gly-Sar), across the apical membrane of human intestinal Caco-2 epithelia, is driven by a proton gradient (Na⁺-free conditions) and displays saturation kinetics (K_m 17.4±5.1 mM, V_max of 92.8±15.6 nmol.cm^–2.h^–1). Net Gly-Sar transport is associated with the stimulation of an inward short-circuit current (I_sc). This dipeptide-stimulated I_sc is observed in both Na⁺-containing and Na⁺-free conditions, is stimulated by apical acidity, and displays saturation kinetics (in Na⁺-free media at apical pH 6.0, K_m of 13.6±4.5 mM and a V_max of 284.1±39.3 nmol.cm^–2.h^–1). The maximal capacities of Gly-Sar transport and I_sc suggest a dipeptide/proton stoichiometry greater than unity (13).     

Further Characterization of an Interleukin-2-1Ike Cytokine Produced by Xenopus Laevis T Lymphocytes

A T-cell growth factor (TCGF) is produced by antigen- or mitogen-stimulated T lymphocytes from the South African clawed frog Xenopus laevis. This study further defines the physical and biological properties of this cytokine and demonstrates that TCGF is biochemically similar to mammalian interleukin-2 (IL-2). Biologically active TCGF eluted from SDS-PAGE displays a M_r of 16 kD and lectin-affinity chromatography indicates that the three-dimensionmal configuration of carbohydrates on TCGF and human IL-2 is similar. Secretion of TCGF is detectable 1 day after stimulation of splenocytes with the T-cell mitogen phytohemagglutinin (PHA) and peaks following 2 to 3 days of stimulation. Finally, despite the biological and physical similarities between Xenopus TCGF and mammalian IL-2, anti-human IL-2 monoclonal antibodies do not recognize Xenopus TCGF.     

Identification of two distinct CD5- B cell subsets from human tonsils with different responses to CD40 monoclonal antibody

This study investigated the response of different CD5^? B cell subsets to CD40 monoclonal antibody (mAb) in various combinations with interleukin (IL)-4 or rabbit anti-human μ chain antibody (a-μ-Ab). The different CD5 B cell subsets were isolated from tonsillar B cell suspensions depleted of CD5⁺ B cells and subsequently fractionated on Percoll density gradients. While resting CD5⁺ B cells proliferated and produced IgM molecules in response to a-μ-Ab, IL-4 and CD40 mAb as well as to Staphylococcus aureus Cowan strain I (SAC) and IL-2, resting CD5^? B cells, which were co-purified in the same 60% Percoll fractions, consistently failed to respond. These cells were, however, activated by the stimuli employed, as demonstrated by their capacity to express the surface activation markers CD69, CD25 and CD71. Resting CD5⁺ B cells had the typical phenotype of mantle zone B cells (IgM⁺ IgD⁺ CD39+ CD38^? CD10^? CDw75^dim), whereas resting CD5^? B cells were CD38^? CD39^? CD 10^? CDw75 intermediate and expressed surface IgM but relatively little surface IgD and could not be classified as mantle zone or germinal center cells. The finding that purified germinal center cells (CD38⁺ CD10⁺ CD39^? CDw75^bright, IgG⁺) responded to CD40 mAb and IL-4 and also to SAC plus IL-2 further underlined the differences to resting CD5^? B cells. However, some of the data collected suggest possible relationships between CD5^? B cells and germinal center cells. The CD5^? B cells isolated from the 50 % Percoll fraction proliferated in response to a-μ-Ab, CD40 mAb and IL-4 as well as to SAC and IL-2. These cells had the same mantle zone B cell phenotype as the CD5⁺ B cells, but their capacity to respond to the stimuli in vitro was unrelated to a possible contamination with CD5⁺ B cells, as documented by the appropriate controls. Furthermore, upon exposure to SAC or phorbol esters, the large majority of CD5^? B cells from the 50 % Percoll fraction did not express surface CD5 and there was very little if any accumulation of CD5 mRNA. Finally, most of the cycling cells in the stimulated CD5^? B cells did not express CD5. The CD5^? B cells from the 50 % Percoll fraction were comprised of a consistent proportion of cells that expressed surface activation markers. The removal of these cells abrogated the capacity of the suspensions to respond to the stimuli in vitro, possibly suggesting that these cells additional activation signals in vivo which were essential to acquire the capacity to respond and that could not be reproduced in vitro. The present study underlines the phenotypic and functional heterogeneity of CD5^? B cells and contributes to the identification of two subsets of these cells which differ in phenotype, tissue distribution and in vitro responses to different stimuli.     

The restoration of permanent immature anterior teeth,root filled using MTA: A review

Objectives

Immature anterior teeth are at high risk of root fracture following root canal treatment. The literature was explored to determine the current status for post-endodontic restorative management of these teeth.

Data and sources

The authors explored multiple search engine databases to November 2008. Experiments included in the review involved simulated human or animal immature teeth with mineral trioxide aggregate as an apical plug. The experiments were designed to assess and compare the fracture strength of teeth restored with various materials. Studies that did not fulfil inclusion criteria were omitted from the review.

Study selection

Four in vitro studies fulfilled selection criteria and were systematically reviewed. All studies differed in sources of teeth, their simulated immature tooth model and mode of force application.

Clinical Implications

Current evidence, mostly from laboratory studies, suggests the use of composite resin materials placed deep into the coronal aspect of the root canal to impart superior fracture resistance. Further clinical research is needed to assess other reinforcing materials, which include a variety of post systems and luting agents.     

Predictive value of congenital hypertrophy of the retinal pigment epithelium as a clinical marker for familial adenomatous polyposis

One hundred forty-eight members of 53 kindreds with familial adenomatous polyposis (FAP) were examined for congenital hypertrophy of the retinal pigment epithelium (CHRPE) and extracolonic manifestations (ECM) to assess the value of CHRPE as a predictive marker for FAP. Based on eye examination results, the families were divided into 2 groups. In a first group of 34 families, all 61 members diagnosed as having polyps and 13 of the 33 patients at risk had 4 or more lesions distributed in both eyes. By contrast, in a second group of 18 families, all 32 polyposis patients and all 18 members at risk had less than 4 lesions. Extracolonic manifestations were present in 26 of 34 families in the first group and in 11 of 18 families in the second group. Data on one family with ambiguous ancestry were reviewed separately. The existence of 4 or more CHRPE lesions distributed in both eyes seems to be a congenital marker for FAP, present in 65.4 percent of families. When present in a family: 1) it is found in all diagnosed patients in that family, 2) can therefore be considered predictive for the development of polyps in other family members who carry the trait, and 3) if confirmed by longer follow-up, may possibly preclude members without the trait from further evaluation and surveillance.Read at the meeting of The American Society of Colon and Rectal Surgeons, Toronto, Canada, June 11 to 16, 1989.     

Effect of Uterine Preservation on Outcome of Laparoscopic Uterosacral Suspension

Study ObjectiveTo compare the objective outcome of laparoscopic uterosacral hysteropexy with that of hysterectomy combined with laparoscopic uterosacral colpopexy.DesignRetrospective cohort study, 1999–2010 (Canadian Task Force classification II-2).SettingUniversity hospital in South Australia.PatientsWomen with uterovaginal prolapse who had undergone laparoscopic uterosacral hysteropexy (n = 104) or laparovaginal hysterectomy with uterosacral colpopexy (n = 160). Apical suspension procedures were subdivided into prophylactic (Pelvic Organ Prolapse Quantification System [POP-Q] stage 1 apical descent, with stage ≥2 prolapse in an adjacent compartment) and therapeutic (POP-Q stage ≥2 apical descent, with or without adjacent compartment prolapse).InterventionsAll patients were assessed via POP-Q scoring preoperatively and postoperatively at 6 weeks, 6 months, annually, and then biannually. Recurrence of bulge symptoms and need for repeat treatment were recorded.Measurements and Main ResultsDemographic data, preoperative degree of prolapse, and percentages of prophylactic and therapeutic procedures were similar in both groups. With a median follow-up of 2.5 years, objective success rates (POP-Q stage <2 in all compartments) for uterosacral hysteropexy were 53% for prophylactic procedures and 41% for therapeutic procedures, and for hysterectomy with uterosacral colpopexy were 66% for prophylactic procedures and 59% for therapeutic procedures. Repeat operation rates overall were 28% for hysteropexy and 21% for hysterectomy with colpopexy. Failures at the apex specifically were 27% for hysteropexy and 11% for hysterectomy with colpopexy (p < .02).ConclusionHysterectomy with laparoscopic uterosacral colpopexy produced better objective success rates than did laparoscopic uterosacral hysteropexy; however, repeat operation rates were not significantly different.