In vitroandin vivoeffect of polycaprolactone nanofiber coating on polyethylene glycol diacrylate scaffolds for intervertebral disc repair.

Polyethylene glycol diacrylate (PEGDA) is an important class of photosensitive polymer with many tissue engineering applications. This study compared PEGDA and polycaprolactone (PCL) nanofiber matrix (NFM) coated PEGDA, referred to as PCL-PEGDA, scaffolds for their application in multiple tissue repair such as articular cartilage, nucleus pulposus of the intervertebral disc (IVD). We examined each scaffold morphology, porosity, swelling ratio, degradation, mechanical strength, andin vitrocytocompatibility properties. A defect was created in Sprague Dawley rat tail IVD by scraping native cartilage tissue and disc space, then implanting the scaffolds in the disc space for 4 weeks to evaluatein vivoefficacy of multi-tissue repair. Maintenance of disc height and creation of a new cell matrix was assessed to evaluate each scaffold's ability to repair the tissue defect. Although both PEGDA and PCL-PEGDA scaffolds showed similar porosity ∼73%, we observed distinct topographical characteristics and a higher effect of degradation on the water-absorbing capacity for PEGDA compared to PCL-PEGDA. Mechanical tests showed higher compressive strength and modulus of PCL-PEGDA compared to PEGDA.In vitrocell studies show that the PCL NFM layer covering PEGDA improved osteoblast cell adhesion, proliferation, and migration into the PEGDA layer.In vivostudies concluded that the PEGDA scaffold alone was not ideal for implantation in rat caudal disc space without PCL nanofiber coating due to low compressive strength and modulus.In vivoresults confirm that the PCL-PEGDA scaffold-maintained disc space and created a proteoglycan and collagen-rich new tissue matrix in the defect site after 4 weeks of scaffold implantation. We concluded that our developed PCL-PEGDA has the potential to be used in multi-tissue defect site repair.

Activation of Stimulator of Interferon Genes (STING) and Sjögren Syndrome.

Sjögren syndrome (SS), a chronic autoimmune disorder causing dry mouth, adversely affects the overall oral health in patients. Activation of innate immune responses and excessive production of type I interferons (IFNs) play a critical role in the pathogenesis of this disorder. Recognition of nucleic acids by cytosolic nucleic acid sensors is a major trigger for the induction of type I IFNs. Upon activation, cytosolic DNA sensors can interact with the stimulator of interferon genes (STING) protein, and activation of STING causes increased expression of type I IFNs. The role of STING activation in SS is not known. In this study, to investigate whether the cytosolic DNA sensing pathway influences SS development, female C57BL/6 mice were injected with a STING agonist, dimethylxanthenone-4-acetic acid (DMXAA). Salivary glands (SGs) were studied for gene expression and inflammatory cell infiltration. SG function was evaluated by measuring pilocarpine-induced salivation. Sera were analyzed for cytokines and autoantibodies. Primary SG cells were used to study the expression and activation of STING. Our data show that systemic DMXAA treatment rapidly induced the expression of Ifnb1, Il6, and Tnfa in the SGs, and these cytokines were also elevated in circulation. In contrast, increased Ifng gene expression was dominantly detected in the SGs. The type I innate lymphoid cells present within the SGs were the major source of IFN-γ, and their numbers increased significantly within 3 d of treatment. STING expression in SGs was mainly observed in ductal and interstitial cells. In primary SG cells, DMXAA activated STING and induced IFN-ß production. The DMXAA-treated mice developed autoantibodies, sialoadenitis, and glandular hypofunction. Our study demonstrates that activation of the STING pathway holds the potential to initiate SS. Thus, apart from viral infections, conditions that cause cellular perturbations and accumulation of host DNA within the cytosol should also be considered as possible triggers for SS.

Volumetric Analysis from a Harmonized Multisite Brain MRI Study of a Single Subject with Multiple Sclerosis.

BACKGROUND AND PURPOSE: MR imaging can be used to measure structural changes in the brains of individuals with multiple sclerosis and is essential for diagnosis, longitudinal monitoring, and therapy evaluation. The North American Imaging in Multiple Sclerosis Cooperative steering committee developed a uniform high-resolution 3T MR imaging protocol relevant to the quantification of cerebral lesions and atrophy and implemented it at 7 sites across the United States. To assess intersite variability in scan data, we imaged a volunteer with relapsing-remitting MS with a scan-rescan at each site. MATERIALS AND METHODS: All imaging was acquired on Siemens scanners (4 Skyra, 2 Tim Trio, and 1 Verio). Expert segmentations were manually obtained for T1-hypointense and T2 (FLAIR) hyperintense lesions. Several automated lesion-detection and whole-brain, cortical, and deep gray matter volumetric pipelines were applied. Statistical analyses were conducted to assess variability across sites, as well as systematic biases in the volumetric measurements that were site-related. RESULTS: Systematic biases due to site differences in expert-traced lesion measurements were significant (P < .01 for both T1 and T2 lesion volumes), with site explaining >90% of the variation (range, 13.0-16.4 mL in T1 and 15.9-20.1 mL in T2) in lesion volumes. Site also explained >80% of the variation in most automated volumetric measurements. Output measures clustered according to scanner models, with similar results from the Skyra versus the other 2 units. CONCLUSIONS: Even in multicenter studies with consistent scanner field strength and manufacturer after protocol harmonization, systematic differences can lead to severe biases in volumetric analyses.

Helicobacter pylori infection stimulates plasminogen activator inhibitor 1 production by gastric epithelial cells.

Chronic infection with the gastric pathogen Helicobacter pylori significantly increases the risk of developing atrophic gastritis, peptic ulcer disease, and gastric adenocarcinoma. H. pylori strains that possess the cag pathogenicity island, which translocates CagA into the host cells, augment these risks. The aim of this study was to determine the molecular mechanisms through which H. pylori upregulates the expression of plasminogen activator inhibitor 1 (PAI-1), a member of the urokinase activator system that is involved in tumor metastasis and angiogenesis. Levels of PAI-1 mRNA and protein were examined in tissues from H. pylori-infected patients and in vitro using AGS gastric epithelial cells. In vitro, cells were infected with toxigenic cag-positive or nontoxigenic cag-negative strains of H. pylori or isogenic mutants. The amount of PAI-1 secretion was measured by enzyme-linked immunosorbent assay, and mRNA levels were determined using real-time PCR. The regulation of PAI-1 was examined using the extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor and small interfering RNA. Analysis of human biopsy samples revealed an increase in both PAI-1 mRNA and protein levels in patients with H. pylori gastritis compared to those of uninfected controls. Infection of AGS cells with H. pylori significantly increased PAI-1 mRNA expression and the secretion of PAI-1 protein. Moreover, PAI-1 mRNA and protein production was more pronounced when AGS cells were infected by H. pylori strains carrying a functional cag secretion system than when cells were infected by strains lacking this system. PAI-1 secretion was also reduced when cells were infected with either cagE-negative or cagA-negative mutants. The ectopic overexpression of CagA significantly increased the levels of PAI-1 mRNA and protein, whereas blockade of the ERK1/2 pathway inhibited H. pylori-mediated PAI-1 upregulation. These findings suggest that the upregulation of PAI-1 in H. pylori-infected gastric epithelial cells may contribute to the carcinogenic process.

Imaging of endoleaks.

The endovascular repair of abdominal aortic aneurysms is gaining widespread acceptance worldwide. It relies on the exclusion of the aneurysm sac from arterial pressure/blood flow to reduce the pressure within it and therefore prevent the fatal complication of rupture. The presence of an endoleak is clear evidence that communication between the native circulation and the aneurysm sac persists. Unfortunately, direct measurement of the sac pressure is not a practical or safe method for routine detection or follow-up of endoleaks. Therefore, a fast, safe, sensitive, and reproducible method must be available. Although many imaging modalities have been and continue to be investigated, computed tomography angiography remains the gold standard. This article describes the various modalities used for the detection of endoleaks and discusses their imaging characteristics.

Postoperative management: type I and III endoleaks.

The purpose of this article is to help the reader understand the importance of imaging findings and treatment strategies for type I and III endoleaks. Although the appearance of these leaks on computed tomography can be somewhat unremarkable and similar in appearance to type II endoleaks, it is critically important for the treating physician to make the correct diagnosis, as these endoleak types signify an incompletely treated aneurysm. Once the diagnosis of a type I or III endoleak is made, the next step in treatment is to identify the cause of the endoleak. Incomplete initial graft expansion, further arterial dilation, endograft migration, component separation, and tears within the graft fabric are all possible causes of type I and III endoleaks. A combination of computed tomography, plain film radiography, and diagnostic angiography may be necessary to make the diagnosis and identify the underlying cause of the complication. Once all of these factors have been determined, a decision has to be made of whether the endoleak can be treated through additional endovascular means or if endovascular therapy has failed for the patient, making open surgical revision necessary to treat the aneurysm. Illustrative cases of all endoleak types and their treatments are the focus of this article.

Correlation between the administered dose of DHEA and serum levels of DHEA and DHEA-S in human volunteers: analysis of published data.

OBJECTIVES: Studies from both experimental animals and humans suggest that administration of exogenous DHEA may have beneficial endocrine-metabolic, immunologic and neurologic effects. Several groups have administered DHEA to humans, but to the best of our knowledge, no one at this point has published a summary of the relationship between the administered dose of DHEA and the serum levels of steroids attained. DESIGN: We summarize the relationship between the administered dose of DHEA and the resulting serum level of DHEA and DHEA-S, in humans, from 18 published articles. RESULTS: Serum levels of DHEA and DHEA-S increase with increasing doses. Doses above 50 mg/day result in levels that are at or above the upper limit of normal for healthy young adults. At doses above 300 mg/day the increment of serum DHEA and DHEA-S appears to reach a plateau. CONCLUSIONS: Those wanting to use supplemental DHEA might consider that doses of 300 mg/day are maximal; they clearly result in supraphysiologic concentrations and above this level doses may have increased side effects without significantly increasing the effective level of serum hormone.

Development and characterization of a gene expression reporter system for Clostridium acetobutylicum ATCC 824.

A gene expression reporter system (pHT3) for Clostridium acetobutylicum ATCC 824 was developed by using the lacZ gene from Thermoanaerobacterium thermosulfurogenes EM1 as the reporter gene. In order to test the reporter system, promoters of three key metabolic pathway genes, ptb (coding for phosphotransbutyrylase), thl (coding for thiolase), and adc (coding for acetoacetate decarboxylase), were cloned upstream of the reporter gene in pHT3 in order to construct vectors pHT4, pHT5, and pHTA, respectively. Detection of beta-galactosidase activity in time course studies performed with strains ATCC 824(pHT4), ATCC 824(pHT5), and ATCC 824(pHTA) demonstrated that the reporter gene produced a functional beta-galactosidase in C. acetobutylicum. In addition, time course studies revealed differences in the beta-galactosidase specific activity profiles of strains ATCC 824(pHT4), ATCC 824(pHT5), and ATCC 824(pHTA), suggesting that the reporter system developed in this study is able to effectively distinguish between different promoters. The stability of the beta-galactosidase produced by the reporter gene was also examined with strains ATCC 824(pHT4) and ATCC 824(pHT5) by using chloramphenicol treatment to inhibit protein synthesis. The data indicated that the beta-galactosidase produced by the lacZ gene from T. thermosulfurogenes EM1 was stable in the exponential phase of growth. In pH-controlled fermentations of ATCC 824(pHT4), the kinetics of beta-galactosidase formation from the ptb promoter and phosphotransbutyrylase formation from its own autologous promoter were found to be similar.

A retrospective analysis of the accuracy of T2-weighted images and dynamic gadolinium-enhanced sequences in the detection and characterization of focal hepatic lesions.

The aim of this study was to determine the relative ability of T2-weighted and dynamic gadolinium-enhanced T1-weighted gradient-echo sequences to detect and characterize focal hepatic lesions. We retrospectively studied 37 patients with proven focal hepatic lesions using the following sequences: a T1-weighted spin-echo sequence (T1), a T2-weighted sequence (T2), and a series of breath-hold dynamic gadolinium-enhanced T1-weighted gradient-echo sequences (Gd). Two observers were asked to determine retrospectively the number and type of focal hepatic lesions present using images from three combinations of sequences (T1+T2, T1+Gd, T1+T2+Gd). Proof of the number and diagnosis of focal lesions in each patient was established using a consensus read. Both readers detected more focal lesions when both the T2-weighted sequences and the gadolinium-enhanced sequences were available than on either sequence alone, although this improvement reached statistical significance (P<0.05) only for one of the readers. There was no significant difference (P<0.05) in the ability to characterize lesions between any of the sets of sequences. The combination of dynamic gadolinium-enhanced images and T2-weighted images was shown to assess focal hepatic lesions better than either of these sequences alone.

Distribution of distant metastases from newly diagnosed non-small cell lung cancer.

BACKGROUND: The purpose of our study was to determine the incidence and locations of M1 disease at presentation in patients with non-small cell lung cancer to help design appropriate preoperative imaging algorithms. METHODS: All patients with non-small cell lung cancer seen between 1991 and 1993 were identified, and records were reviewed. For patients with M1 disease, the sites of distant metastases and the methods of diagnosis were recorded. RESULTS: Of 348 patients identified, 276 (79%) had M0 disease and 72 (21%) had M1 disease. In 40 of 72 patients (56%), M1 disease was detected via chest or abdominal computed tomography (CT). Brain, bone, liver, and adrenal glands were the most common sites of metastatic disease, in decreasing order. Brain metastases often occurred as an isolated finding, although isolated liver metastases were uncommon. CONCLUSIONS: M1 disease was common at presentation, and was often detectable via chest CT. The incremental yield of abdominal CT over chest CT was very small, and therefore abdominal CT is not an effective method of screening for metastases if chest CT has been performed.