Nanoparticle-based therapy in an in vivo microRNA-155 (miR-155)-dependent mouse model of lymphoma

MicroRNA-155 (miR-155) is an oncogenic microRNA that regulates several pathways involved in cell division and immunoregulation. It is overexpressed in numerous cancers, is often correlated with poor prognosis, and is thus a key target for future therapies. In this work we show that overexpression of miR-155 in lymphoid tissues results in disseminated lymphoma characterized by a clonal, transplantable pre-B-cell population of neoplastic lymphocytes. Withdrawal of miR-155 in mice with established disease results in rapid regression of lymphadenopathy, in part because of apoptosis of the malignant lymphocytes, demonstrating that these tumors are dependent on miR-155 expression. We show that systemic delivery of antisense peptide nucleic acids encapsulated in unique polymer nanoparticles inhibits miR-155 and slows the growth of these "addicted" pre-B-cell tumors in vivo, suggesting a promising therapeutic option for lymphoma/leukemia.     

Ursodeoxycholic acid in patients with ulcerative colitis and primary sclerosing cholangitis for prevention of colon cancer: a meta-analysis

Purpose/Aim

Colon cancer risk is high in patients with ulcerative colitis (UC) and primary sclerosing cholangitis (PSC). Ursodeoxycholic acid has been shown to have some promise as a chemopreventive agent. A meta-analysis was performed to compare the efficacy of ursodeoxycholic acid in the prevention of colonic neoplasia in patients with UC and PSC.

Methods

Multiple databases were searched (January 2011). Studies examining the use of ursodeoxycholic acid vs. no ursodeoxycholic acid or placebo in adult patients with UC and PSC were included. Data were extracted in standard forms by two independent reviewers. Meta-analysis for the effect of ursodeoxycholic acid was performed by calculating pooled estimates of adenoma or colon cancer formation by odds ratio (OR) with random effects model. Heterogeneity was assessed by calculating the I ² measure of inconsistency. RevMan 5 was utilized for statistical analysis.

Results

Four studies (n?=?281) met the inclusion criteria. The studies were of adequate quality. Ursodeoxycholic acid demonstrated no overall improvement in adenoma (OR 0.53; 95?% CI: 0.19?1.48, p?=?0.23) or colon cancer occurrence (OR 0.50; 95?% CI: 0.18?1.43, p?=?0.20) as compared to no ursodeoxycholic acid or placebo in patients with UC and PSC.

Conclusion

Ursodeoxycholic acid use in patients with UC and PSC does not appear to decrease the risk of adenomas or colon cancer.     

Left atrial volume by echocardiography in patients with false positive myocardial perfusion scans

A stress-induced myocardial perfusion abnormality (MPS), in the absence of angiographically significant epicardial coronary artery disease, is considered a "false-positive" test result. We hypothesized that echocardiography would provide complementary prognostic and pathophysiologic data relevant to the management of patients with MPS and normal coronary angiograms. Accordingly, left atrial volume index (LAVi) was assessed by echocardiography in 38 patients with false positive MPS as defined by normal coronary angiograms and 26 patients with true negative MPS from a total of 1,356 patients stressed from July 2006-May 2008. Pathologically abnormal elevation of LAVi (≥ 32 mL/m(2)) was observed in 16 of 19 women (84%) and 11 of 19 men (58%) in the false positive MPS (FPMPS) group while none of the patients in the true negative MPS (TNMPS) group had elevated LAVi. In the FPMPS group mean LAVi was significantly higher in women than men (40.64 ± 11.4 mL/m(2) versus 32.6 ± 10.5 mL/m(2), P = 0.01). The mean LAVi in the FPMPS group was significantly different from the TNMPS group (36.6 ± 11.6 versus 21 ± 7 mL/m(2), P = 0.000). A stepwise logistic regression determined BSA, LAV and LAVi as useful in predicting false positive and true negative MPS. All three were significant predictors (P < 0.01) and the area under the ROC curve was 0.91. Our findings in this relatively small cohort suggest that patients with false positive MPS have a greater increased LAVi.     

Sulfur Mobilization for Fe-S Cluster Assembly by the Essential SUF Pathway in the Plasmodium falciparum Apicoplast and Its Inhibition

The plastid of the malaria parasite, the apicoplast, is essential for parasite survival. It houses several pathways of bacterial origin that are considered attractive sites for drug intervention. Among these is the sulfur mobilization (SUF) pathway of Fe-S cluster biogenesis. Although the SUF pathway is essential for apicoplast maintenance and parasite survival, there has been limited biochemical investigation of its components and inhibitors of Plasmodium SUFs have not been identified. We report the characterization of two proteins, Plasmodium falciparum SufS (PfSufS) and PfSufE, that mobilize sulfur in the first step of Fe-S cluster assembly and confirm their exclusive localization to the apicoplast. The cysteine desulfurase activity of PfSufS is greatly enhanced by PfSufE, and the PfSufS-PfSufE complex is detected in vivo. Structural modeling of the complex reveals proximal positioning of conserved cysteine residues of the two proteins that would allow sulfide transfer from the PLP (pyridoxal phosphate) cofactor-bound active site of PfSufS. Sulfide release from the l-cysteine substrate catalyzed by PfSufS is inhibited by the PLP inhibitor d-cycloserine, which forms an adduct with PfSufS-bound PLP. d-Cycloserine is also inimical to parasite growth, with a 50% inhibitory concentration close to that reported for Mycobacterium tuberculosis, against which the drug is in clinical use. Our results establish the function of two proteins that mediate sulfur mobilization, the first step in the apicoplast SUF pathway, and provide a rationale for drug design based on inactivation of the PLP cofactor of PfSufS.     

Effect of myocardial contractility on hemodynamic end points under concomitant microvascular disease in a porcine model

In this study, coronary diagnostic parameters, pressure drop coefficient (CDP: ratio of trans-stenotic pressure drop to distal dynamic pressure), and lesion flow coefficient (LFC: ratio of % area stenosis (%AS) to the CDP at throat region), were evaluated to distinguish levels of %AS under varying contractility conditions, in the presence of microvascular disease (MVD). In 10 pigs, %AS and MVD were created using angioplasty balloons and 90-μm microspheres, respectively. Simultaneous measurements of pressure drop, left ventricular pressure (p), and velocity were obtained. Contractility was calculated as (dp/dt)_max, categorized into low contractility <900 mmHg/s and high contractility >900 mmHg/s, and in each group, compared between %AS <50 and >50 using analysis of variance. In the presence of MVD, between the %AS <50 and >50 groups, values of CDP (71 ± 1.4 and 121 ± 1.3) and LFC (0.10 ± 0.04 and 0.19 ± 0.04) were significantly different (P < 0.05), under low-contractility conditions. A similar %AS trend was observed under high-contractility conditions (CDP: 18 ± 1.4 and 91 ± 1.4; LFC: 0.08 ± 0.04 and 0.25 ± 0.04). Under MVD conditions, similar to fractional flow reserve, CDP and LFC were not influenced by contractility.     

Label-free imaging of Schwann cell myelination by third harmonic generation microscopy

Understanding the dynamic axon–glial cell interaction underlying myelination is hampered by the lack of suitable imaging techniques. Here we demonstrate third harmonic generation microscopy (THGM) for label-free imaging of myelinating Schwann cells in live culture and ex vivo and in vivo tissue. A 3D structure was acquired for a variety of compact and noncompact myelin domains, including juxtaparanodes, Schmidt–Lanterman incisures, and Cajal bands. Other subcellular features of Schwann cells that escape traditional optical microscopies were also visualized. We tested THGM for morphometry of compact myelin. Unlike current methods based on electron microscopy, g-ratio could be determined along an extended length of myelinated fiber in the physiological condition. The precision of THGM-based g-ratio estimation was corroborated in mouse models of hypomyelination. Finally, we demonstrated the feasibility of THGM to monitor morphological changes of myelin during postnatal development and degeneration. The outstanding capabilities of THGM may be useful for elucidation of the mechanism of myelin formation and pathogenesis.Myelin is a multiple-layered membrane sheath surrounding the axon. In myelinated nerves, the conduction of action potentials is much faster and the speed depends strongly on the structure of myelin. The structural integrity must be therefore tightly regulated for proper conduction of neuronal impulses, but the underlying axon–glial cell interaction is not well understood. Since the days of Ramón y Cajal, light microscopy has been widely used to visualize myelin morphology (1). A variety of fluorescent probes specifically binding to myelin components have allowed studies of the interaction between molecules (2–4). However, most such labeling methods are not suitable for unraveling in vivo dynamics of myelination because cell membranes are compromised during staining (especially immunohistochemistry) and/or the procedures are prohibitively time-consuming and invasive. It is thus of great interest to develop label-free methods. Recently, spectral confocal reflectance microscopy has been demonstrated for high-resolution in vivo imaging of myelin (5). There are also techniques of nonlinear optical microscopy, which are generally known to be more advantageous for imaging deep live tissue. Coherence anti-Stokes Raman scattering (CARS) microscopy, which requires two synchronized short pulse lasers for excitation, has been used for imaging in vivo myelin and detecting pathology (6, 7). Third harmonic generation (THG) microscopy is based on another nonlinear optical process of light emission, yielding distinguishable images from CARS. Though it has been demonstrated for imaging the white matter in the brain (8), so far few studies have applied THG microscopy (THGM) for elucidating the mechanism of myelin formation. Moreover, the omission of the peripheral nervous systems (PNS) in the previous studies is not trivial considering the significant departure from the CNS in terms of the myelin-forming glia and molecular subdomains: Schwann cells wrap individual internodes in the PNS, and oligodendrocytes form multiple myelin sheaths in the CNS. The basal lamina and nodal microvilli are unique to Schwann cells, and Schmidt–Lanterman incisures are more pronounced in the PNS (9). Here we demonstrate, to our knowledge for the first time, the utility of THGM as a method for morphological analysis of myelinating Schwann cells in live culture and ex vivo and in vivo tissue.