Magnetic Resonance Imaging Evaluation of Ectopic Pregnancy: A Value-Added Review.

ABSTRACT: Ectopic pregnancy (EP) is a known cause of maternal mortality and may be misdiagnosed in up to 50% of pregnant female individuals (Ann Emerg Med. 1996;28(1):10-17). Magnetic resonance imaging, with its superior soft tissue resolution, is a valuable alternative diagnostic modality to diagnose EP when transvaginal ultrasound results are inconclusive. Although an extrauterine gestational sac is the most specific finding, there are other key MRI findings that can aid in diagnosing EP. As availability of MRI access in the emergency department setting increases across the nation, its utility in women with a positive pregnancy test has also increased. Specific MRI findings that are diagnostic of EP include absence of intrauterine pregnancy, adnexal mass separate from the ovary, and hemoperitoneum. In addition, intrauterine ectopic locations, especially intramural, cornual, and cervical pregnancies, can be diagnosed with increased accuracy with the help of MRI. Magnetic resonance imaging is also useful in excluding potential mimics of EP, including adnexal cysts, ovarian neoplasms, and fibroids. In summary, providing an accurate diagnosis and determining the precise location of an EP, which is supported by the use of MRI, is imperative for guiding a patient's treatment to prevent a potentially fatal outcome.

Targeted Injection of a Truncated Form of Tissue Inhibitor of Metalloproteinase 3 Alters Post-Myocardial Infarction Remodeling.

Infarct expansion can occur after myocardial infarction (MI), which leads to adverse left ventricular (LV) remodeling and failure. An imbalance between matrix metalloproteinase (MMP) induction and tissue inhibitors of MMPs (TIMPs) can accelerate this process. Past studies have shown different biologic effects of TIMP-3, which may depend upon specific domains within the TIMP-3 molecule. This study tested the hypothesis that differential effects of direct myocardial injections of either a full-length recombinant TIMP-3 (F-TIMP-3) or a truncated form encompassing the N-terminal region (N-TIMP-3) could be identified post-MI. MI was induced in pigs that were randomized for MI injections (30 mg) and received targeted injections within the MI region of F-TIMP-3 (n = 8), N-TIMP-3 (n = 9), or saline injection (MI-only, n = 11). At 14 days post-MI, LV ejection fraction fell post-MI but remained higher in both TIMP-3 groups. Tumor necrosis factor and interleukin-10 mRNA increased by over 10-fold in the MI-only and N-TIMP-3 groups but were reduced with F-TIMP-3 at this post-MI time point. Direct MI injection of either a full-length or truncated form of TIMP-3 is sufficient to favorably alter the course of post-MI remodeling. The functional and differential relevance of TIMP-3 domains has been established in vivo since the TIMP-3 constructs demonstrated different MMP/cytokine expression profiles. These translational studies identify a unique and more specific therapeutic strategy to alter the course of LV remodeling and dysfunction after MI. SIGNIFICANCE STATEMENT: Using different formulations of tissue inhibitor of matrix metalloproteinase-3 (TIMP-3), when injected into the myocardial infarction (MI) region, slowed the progression of indices of left ventricular (LV) failure, suggesting that the N terminus of TIMP-3 is sufficient to attenuate early adverse functional events post-MI. Injections of full-length recombinant TIMP-3, but not of the N-terminal region of TIMP-3, reduced relative indices of inflammation at the mRNA level, suggesting that the C-terminal region affects other biological pathways. These unique proof-of-concept studies demonstrate the feasibility of using recombinant small molecules to selectively interrupt adverse LV remodeling post-MI.

Injectable and bioresponsive hydrogels for on-demand matrix metalloproteinase inhibition.

Inhibitors of matrix metalloproteinases (MMPs) have been extensively explored to treat pathologies where excessive MMP activity contributes to adverse tissue remodelling. Although MMP inhibition remains a relevant therapeutic target, MMP inhibitors have not translated to clinical application owing to the dose-limiting side effects following systemic administration of the drugs. Here, we describe the synthesis of a polysaccharide-based hydrogel that can be locally injected into tissues and releases a recombinant tissue inhibitor of MMPs (rTIMP-3) in response to MMP activity. Specifically, rTIMP-3 is sequestered in the hydrogels through electrostatic interactions and is released as crosslinks are degraded by active MMPs. Targeted delivery of the hydrogel/rTIMP-3 construct to regions of MMP overexpression following a myocardial infarction significantly reduced MMP activity and attenuated adverse left ventricular remodelling in a porcine model of myocardial infarction. Our findings demonstrate that local, on-demand MMP inhibition is achievable through the use of an injectable and bioresponsive hydrogel.

Cardiac-restricted overexpression or deletion of tissue inhibitor of matrix metalloproteinase-4: differential effects on left ventricular structure and function following pressure overload-induced hypertrophy.

Historically, the tissue inhibitors of matrix metalloproteinases (TIMPs) were considered monochromatic in function. However, differential TIMP profiles more recently observed with left ventricular (LV) dysfunction and matrix remodeling suggest more diverse biological roles for individual TIMPs. This study tested the hypothesis that cardiac-specific overexpression (TIMP-4OE) or deletion (knockout; TIMP-4KO) would differentially affect LV function and structure following pressure overload (LVPO). LVPO (transverse aortic constriction) was induced in mice (3.5 ± 0.1 mo of age, equal sex distribution) with TIMP-4OE (n = 38), TIMP-4KO (n = 24), as well as age/strain-matched wild type (WT, n = 25), whereby indexes of LV remodeling and function such as LV mass and ejection fraction (LVEF) were determined at 28 days following LVPO. Following LVPO, both early (7 days) and late (28 days) survival was ~25% lower in the TIMP-4KO group (P < 0.05). While LVPO increased LV mass in all groups, the relative hypertrophic response was attenuated with TIMP-4OE. With LVPO, LVEF was similar between WT and TIMP-4KO (48 ± 2% and 45 ± 3%, respectively) but was higher with TIMP-4OE (57 ± 2%, P < 0.05). With LVPO, LV myocardial collagen expression (type I, III) increased by threefold in all groups (P < 0.05), but surprisingly this response was most robust in the TIMP-4KO group. These unique findings suggest that increased myocardial TIMP-4 in the context of a LVPO stimulus may actually provide protective effects with respect to survival, LV function, and extracellular matrix (ECM) remodeling. These findings challenge the canonical belief that increased levels of specific myocardial TIMPs, such as TIMP-4 in and of themselves, contribute to adverse ECM accumulation following a pathological stimulus, such as LVPO.

Targeted injection of a biocomposite material alters macrophage and fibroblast phenotype and function following myocardial infarction: relation to left ventricular remodeling.

A treatment target for progressive left ventricular (LV) remodeling prevention following myocardial infarction (MI) is to affect structural changes directly within the MI region. One approach is through targeted injection of biocomposite materials, such as calcium hydroxyapatite microspheres (CHAM), into the MI region. In this study, the effects of CHAM injections upon key cell types responsible for the MI remodeling process, the macrophage and fibroblast, were examined. MI was induced in adult pigs before randomization to CHAM injections (20 targeted 0.1-ml injections within MI region) or saline. At 7 or 21 days post-MI (n = 6/time point per group), cardiac magnetic resonance imaging was performed, followed by macrophage and fibroblast isolation. Isolated macrophage profiles for monocyte chemotactic macrophage inflammatory protein-1 as measured by real-time polymerase chain reaction increased at 7 days post-MI in the CHAM group compared with MI only (16.3 ± 6.6 versus 1.7 ± 0.6 cycle times values, P < 0.05), and were similar by 21 days post-MI. Temporal changes in fibroblast function and smooth muscle actin (SMA) expression relative to referent control (n = 5) occurred with MI. CHAM induced increases in fibroblast proliferation, migration, and SMA expression-indicative of fibroblast transformation. By 21 days, CHAM reduced LV dilation (diastolic volume: 75 ± 2 versus 97 ± 4 ml) and increased function (ejection fraction: 48 ± 2% versus 38 ± 2%) compared with MI only (both P < 0.05). This study identified that effects on macrophage and fibroblast differentiation occurred with injection of biocomposite material within the MI, which translated into reduced adverse LV remodeling. These unique findings demonstrate that biomaterial injections impart biologic effects upon the MI remodeling process over any biophysical effects.