5519498
Non-invasive quantification of brain tumor-induced astrogliosis
BackgroundCNS injury including stroke, infection, and tumor growth lead to astrogliosis, a process that involves upregulation of glial fibrillary acidic protein (GFAP) in astrocytes. However, the kinetics of astrogliosis that is related to these insults (i.e. tumor) is largely unknown.ResultsUsing transgenic mice expressing firefly luciferase under the regulation of the GFAP promoter (GFAP-luc), we developed a model system to monitor astrogliosis upon tumor growth in a rapid, non-invasive manner. A biphasic induction of astrogliosis was observed in our xenograft model in which an early phase of activation of GFAP was associated with inflammatory response followed by a secondary, long-term upregulation of GFAP. These animals reveal GFAP activation with kinetics that is in parallel with tumor growth. Furthermore, a strong correlation between astrogliosis and tumor size was observed.ConclusionsOur results suggest that non-invasive, quantitative bioluminescent imaging using GFAP-luc reporter animal is a useful tool to monitor temporal-spatial kinetics of host-mediated astrogliosis that is associated with glioma and metastatic brain tumor growth.
32880620
In vivo measurement of glioma-induced vascular permeability.
The normal blood-brain barrier (BBB) consists of tight interendothelial cell junctions and adjacent astrocyte end feet separated by a basal lamina surrounding the endothelium. The interactions between the different cell types of BBB are disrupted in distinct patterns in the microenvironment of glioma. Malignant gliomas infiltrate the surrounding normal brain parenchyma; a process associated with vascular permeability (VP) and breakdown of the BBB. Herein, we describe methods to quantitatively measure glioma-induced vascular permeability, utilizing an orthotopic xenograft model of glioma.
207620666
Conditional deletion of the focal adhesion kinase FAK alters remodeling of the blood-brain barrier in glioma.
Gliomas generally infiltrate the surrounding normal brain parenchyma, a process associated with increased vascular permeability (VP) and dysregulation of the blood-brain barrier (BBB). However, the molecular mechanisms underlying glioma-induced VP in the brain remain poorly understood. Using a conditional, endothelium-specific deletion of the focal adhesion kinase (FAK) in the mouse (FAK CKO), we show that FAK is critical for destabilization of the tumor endothelium in tumor-bearing mice, with mutant mice exhibiting a relatively normalized vasculature compared with wild-type mice (FAK WT). Tumor vessels in the FAK CKO mice displayed reduced VP compared with FAK WT mice, resulting in reduced tumor growth. Additionally, FAK CKO mice displayed partial restoration of cell-cell junction proteins in the tumor vessels and astrocyte-endothelium interactions in tumors, revealing an additional role of astrocytes in mediating tumor-induced VP. Together, these results provide genetic evidence that FAK is a mediator of tumor-induced VP in the brain. Our findings may help understand how therapeutics might be used to regulate specific cell-type interactions to restore BBB structure/function in cancer and perhaps other pathologic conditions.
21038080
Enhancedex vivo buccal transport of propranolol: Evaluation of phospholipids as permeation enhancers
The aim of the present study was to evaluate the effects of two phospholipid permeation enhancers, lysophosphatidylcholine (LPC) and didecanoylphosphatidylcholine (DDPC), along with a fusidic acid derivative, sodium taurodihydrofusidate (STDHF) and ethanol (EtOH) on the buccal transport of propranolol hydrochloride (PPL) using anex vivo buccal diffusion model. The permeation rate of [3H]PPL as measured by steady-state fluxes increased with increasing EtOH concentration. A significant flux enhancement (P<0.05) was achieved by EtOH at 20 and 30 %v/v concentrations. At a 0.5 %w/v permeation enhancer concentration, the buccal permeation of [3H]PPL was significantly enhanced by all the enhancers studied (i.e., LPC, DDPC and STDHF) compared to the control (phosphate-buffered saline pH 7.4, PBS). LPC and DDPC displayed a greater degree of permeation enhancement compared with STDHF and EtOH-PBS mixtures with an enhancement ratio of 3.2 and 2.9 for LPC and DDPC, respectively compared with 2.0 and 1.5 for STDHF and EtOH:PBS 30:70 %v/v mixture, respectively. There was no significant difference between LPC and DDPC for the flux values and apparent permeability coefficients of [3H]PPL. These results suggest that phospholipids are suitable as permeation enhancers for the buccal delivery of drugs.
38537498
Gallbladder damage control: compromised procedure for compromised patients
BackgroundThe objective of this study was to analyze a population-based database for (1) recent 9-year trends in utilization of partial cholecystectomy (PC), laparoscopic PC, and trocar cholecystostomy (TC), (2) demographics, associated diagnoses, and hospital characteristics, and (3) relevant inpatient outcomes.MethodsRetrospective cohort analysis of the Nationwide Inpatient Sample (NIS) files from 2000 to 2008 was performed. For the purposes of the study, gallbladder damage control was defined as PC, laparoscopic PC, and TC.ResultsA national estimate of 10,872 gallbladder damage control cases was obtained. Procedures performed included PC (47.8 %), laparoscopic PC (27.2 %), TC (25.3 %), and intraoperative cholangiogram (IOC) (19.7 %). A total of 1,479 (13.6 %) postoperative complications were identified, including pulmonary complications (4.3 %), hemorrhage/hematoma/seroma (3.4 %), and accidental puncture or laceration during procedure (3.3 %). Common bile duct injury occurred in 3.3 % overall. Hospital types included nonteaching (82.1 %) and urban (67.8 %), with regional variations of 42.1 % from the South and 45.2 % from the West. Inpatient outcomes included mean length of stay of 11.4 (0.16 SEM) days, mean total hospital charge of $71,296.69 ($1,106.03 SEM), 7.4 % mortality, and 16.8 % discharge to skilled nursing facility. Multivariate logistic regression analysis identified independent risk variables for common bile duct injury: teaching hospitals (OR = 1.517, CI = 1.155–1.991, P = 0.003). IOC (OR = 2.030, CI = 1.590–2.591, P < 0.001) was a commonly associated procedure in the setting of common bile duct injury.ConclusionVarious circumstances may require gallbladder damage control with PC and TC. Postoperative complications and common bile duct injury remain significantly high despite limited resection, and the teaching status of the hospital is associated with CBD injury. High morbidity and mortality of gallbladder damage control may reflect both the compromised nature of the procedures and multiple comorbidities.
24557128
Activation of Ets-2 by oxidative stress induces Bcl-xL expression and accounts for glial survival in amyotrophic lateral sclerosis.
Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease characterized by selective degeneration of motor neurons and glial activation. Cell-specific transcriptional regulation induced by oxidative stress may contribute to the survival and activation of astrocytes in the face of motor neuron death. In the present study, we demonstrate an age-dependent increase in Bcl-xL and Ets-2 immunoreactivity that correlates with an increase of glial fibrillary acidic protein (GFAP)-positive cells in the ventral horn of the spinal cord in both ALS transgenic mice [mutant SOD1 (G93A)] and affected humans. Chromatin immunoprecipitation (ChIP) analysis verified that Ets-2 preferentially occupies the Ets-2 binding element in the promoter of Bcl-xL in primary astrocytes under oxidative stress conditions as well as in G93A spinal cords. Ets-2 small-interfering RNA down-regulated the transcriptional activity of Bcl-xL. In primary glial cultures, Bcl-xL overexpression and mutant SOD1 (G93A) both conferred resistance to oxidative stress-induced cell death. Our findings suggest that Ets-2 transcription factor activation of Bcl-xL gene may protect glia from constitutive oxidative stress that is thought to be a key mechanism contributing to the pathogenesis of ALS. This survival pathway may contribute to the glial survival and activation seen in the spinal cord of ALS patients.
9605549
Spectrum measurement of fast optical signal of neural activity in brain tissue and its theoretical origin
Functional brain imaging technologies have enabled recent advances in understanding human brain function. In particular, a noninvasive and fast optical technique will become one of the most promising tools for future studies. As a fundamental ex vivo study for the development of such a technique, this paper demonstrates the spectral measurement of fast optical changes associated with neural activity in bulk brain tissue. For this purpose, a high-speed confocal near-infrared spectrometer was built and used. The results verified that observed transient optical responses (tORs) are associated with neural activity by showing that the following: tORs were concurrent and correlated with local field potentials (LFPs); tORs disappeared following tetrodotoxin application; and tORs were reproducibly observed across preparations. In addition, the amplitude of tORs was statistically significantly larger in longer wavelengths (approximately 1200 nm). The time course of tORs, however, is quite different from that of LFPs. Since this difference implies that tORs may originate not directly from the electric potential variation but from other neurophysiological events accompanying excitation, this paper tested the hypothesis that tORs are attributed to transient cellular volume changes (tCVCs). With no previous dynamic equation to elucidate such different temporal dynamics of the optical responses, a novel mathematical neuron model to describe tCVCs was developed. This neuron model, along with finite-difference time-domain simulations, showed that tCVCs and tORs were similar in the temporal dynamics, order of magnitude, response direction, and detectability in the bulk tissue; thus supporting the hypothesis.
33491527
Exact partition function zeros of the Wako-Saitô-Muñoz-Eaton β hairpin model.
I compute exact partition function zeros of β hairpins, using both analytic and numerical methods, extending previous work [J. Lee, Phys. Rev. Lett. 110, 248101 (2013)] where only a restricted class of hairpins was considered. The zeros of β hairpins with an odd number of peptide bonds are computed and the difference of the distribution of zeros from those for an even number of peptide bonds is explained in terms of additional entropy of liberating the extra bond at the turn region. Upon the introduction of a hydrophobic core in the central region of the hairpin, the zeros are distributed uniformly on two concentric circles corresponding to the hydrophobic collapse and the transition to the fully folded conformation. One of the circles dissolves as the core moves toward the turn or the tip region, which is explained in terms of the similarity of the intermediate state with the folded or unfolded states. The exact partition function zeros for a hairpin with a more complex structure of native contacts, the 16 C-terminal residues of streptococcal protein G B1, are numerically computed and their loci are closely approximated by concentric circles.