The process is accelerated after age 37, ultimately culminating in the virtual absence of follicles and capacity to generate significant quantities of estradiol. The median chronological age at menopause in the USA is 51.4 years (range 48 to 55 years). Estrogen decrease is associated with substantial thing central nervous system (CNS) alterations including vasomotor instability, insomnia, depression, and cognitive decline.123 Recent, Inhibitors,research,lifescience,medical studies suggest that estrogen has a protective effect with respect to onset of Alzheimer’s disease and cognitive decline.124 There is evidence

that neurobiologie processes triggered by the hormonal changes exert influence by affecting neurotransmitter availability, cerebral perfusion, and perhaps by Inhibitors,research,lifescience,medical eliminating neuroprotective effects of estrogen.125,126 In a recent study by Matteis et al,96 using transcranial Doppler ultrasonography, they found, as we did, higher flow estimates in women than men overall. However, a subgroup of 15 postmenopausal women aged 48 to 53 years had lower flow values than 15 premenopausal women of the same age, or any other group. Conclusions There is increasing evidence across behavioral, neuroanatomic, and neurophysiologic domains that sex differences play a prominent role in modulating the effects of

aging on brain function. The Inhibitors,research,lifescience,medical overall finding is that age-related decline begins earlier in men than in women. The decline is most pronounced in frontotemporal regions associated Inhibitors,research,lifescience,medical with attention, inhibition, and memory. More specific tasks using a computerized approach can help better delineate associations between agerelated decline and aspects of cognitive and emotion processing. Inhibitors,research,lifescience,medical The sex differences

in brain aging may be further investigated on the molecular level and data on other physiologic parameters, such as glucose and oxygen metabolism and receptor function, could help further elucidate mechanisms for Y-27632 2HCL explaining these differences. Such studies could ultimately help explain a range of phenomena related to sex differences including cognition and emotion processing. Although we have focused on findings GSK-3 in healthy people, the effects have implications for brain disorders where gender differences have been observed across the life span. For example, neurodevelopmental disorders such as attention deficit and learning disabilities are more common in boys, schizophrenia is more severe in young men, and depression is more common in women. Understanding the neural basis of these disorders can be advanced by considering sex differences in brain function. The clinical implications of these findings need to be examined in relation to disease presentation and course.

Continuation treatment consisted of combined NT and IPT, using the same dose of NT (an average of 85 mg/day, but with a range of 20 to 200 mg/day) as during acute therapy, but reducing the frequency of IPT to twice monthly. Patients with stable remission and recovery entered the experimental maintenance phase of the study, via double-blind random assignment to one of four longterm treatment conditions:

Inhibitors,research,lifescience,medical (i) medication clinic with NT; (ii) medication clinic with placebo; (iii) monthly maintenance IPT with NT; and (iv) monthly maintenance IPT with placebo. Patients remained in maintenance things therapy for 3 years, or until recurrence of major depression, whichever occurred first. Survival analysis tested differences in rates of recurrence and time to recurrence. Outcomes of therapy at each phase of treatment: acute, continuation, and maintenance Acute

treatment Of 187 patients who signed informed consent to participate, 5 showed spontaneous remission and 2 declined to begin treatment. Thus, 180 patients Inhibitors,research,lifescience,medical actually began acute treatment with NT and IPT, and of these 159 completed acute-phase treatment (140 remitters and 19 nonresponders). Twenty-one patients dropped out of Inhibitors,research,lifescience,medical acute-phase treatment, 8 refusing further treatment, 6 developing medical conditions contraindicating NT, 2 being noncompliant, and 1 each dying or becoming delusional or manic. The median time to remission Inhibitors,research,lifescience,medical in this sample was 12 weeks,16 and the earliest point of statistically reliable discrimination of recovering and nonrecovering patients was 4 weeks.17 Almost one third (30.5%) showed rapid sustained response to combined treatment with NT and IPT, ie, they were well by 4 weeks. Other patients remitted more slowly, by 8 to 10 weeks (22.1%), while the remaining patients showed partial or mixed response. Slower and more variable treatment response was associated with higher pretreatmcnt levels of anxiety, lower levels of social support, greater current age at study entry, and higher percentage of rapid eye movement (REM) sleep selleck chem Bortezomib before the initiation of treatment.15 Subjects with earlier-onset depressive Inhibitors,research,lifescience,medical illness (ic, first episode prior to age 60) took on

average 5 to 6 weeks longer to achieve remission, possibly a reflection of the greater number of prior lifetime episodes GSK-3 (chronicity).18 Because early-onset subjects also had a higher rate of past suicide attempts, we concluded that they need especially careful surveillance during acute treatment, since they are likely to take longer to respond. Continuation treatment Of the 140 remitters who entered continuation treatment, 124 met study criteria for recovery at the end of 16 weeks of continuation treatment. Nine patients relapsed and could not be restabilized. Seven subjects dropped out of treatment, either noncompliant or refusing further treatment altogether. TTms, 124 patients were randomly assigned to a long-term maintenance therapy condition.

4 per 1 000 inhabitants per year of acutely ill patients with chest pain or suspected acute myocardial infarction was found. In a previous study [1] we presented data from three EMCCs after gathering information on every situation that was triaged as a red response, according to the Norwegian Index of Medical Emergencies. The study showed that 90% of the red responses were medical problems with a large variation of symptoms, the remainder being accidents. Severity of illness was classified retrospectively,

and showed Inhibitors,research,lifescience,medical that 70% of the patients were not in a life-threatening situation. The aim of the present analyses was to obtain representative data on the epidemiology of acute chest pain outside the hospitals in Norway, by a more detailed investigation of the data from our EMCC study. Methods Three EMCCs, located at Haugesund, Stavanger and Innlandet hospitals, were involved in the study, with the three Inhibitors,research,lifescience,medical corresponding districts covering 816 000 inhabitants (18% of the total Norwegian population). Data were collected Inhibitors,research,lifescience,medical prospectively from October 1 to December 31 2007. Variables All 19 EMCCs in Norway use a software system called Acute Medical Information System (AMIS) to record all incoming cases. Usage of the AMIS results in an electronic form with registration of each incident

(not the individual patient). The AMIS form contains information about the incident, the patient (or patients, if more than one patient is involved in the incident) and all available logistics, including date, time of day, and to where the patients are transported (“left at scene”, home, casualty clinic,

hospital). Prehospital response time is also registered, Inhibitors,research,lifescience,medical defined as the time period from when the caller calls 113 until the nearest available ambulance reaches the patient [9,10]. Based on the immediate available information, the EMCC operator (usually a specially trained Inhibitors,research,lifescience,medical nurse) gives the incident one clinical criteria code and one response level according to the Index [6]. The Index is based on ideas from the Criteria Based Dispatch system in the US [11], and was first published in 1994. It selleck chemical Volasertib categorises clinical Cilengitide symptoms, findings and incidents into 39 chapters, and each chapter is subdivided into a red, yellow and green criteria based section, correlating to the appropriate level of response. Red cell differentiation colour is defined as an “acute” response, with the highest priority, and will trigger the transmission of a radio alarm to both the primary care doctor on-call and the ambulance service. Yellow colour is defined as an “urgent” response, with a high, but lower priority, where the patient should be examined as soon as the doctor-on-call is available. Green colour is defined as a “non-urgent” response, with the lowest priority. Chapter 10 in the Index covers the symptom “Chest pain”, and usage of the red response section will result in the code A10 – Chest pain (A for “acute”).

2003; Werner et al. 2005; Fadini et al. 2007; Rouhl et al. 2008), although other studies reported conflicting results (Eizawa et al. 2004; Kunz et al. 2006; Hristov et al. 2007; Xiao et al. 2007). Conversely, statins, estrogen, erythropoietin, angiotensin-converting enzyme inhibitors and physical exercise tend

to increase EPC counts (Werner et al. 2005; Fadini et al. 2007). Clearly, as EPC may play an important role in the pathophysiology of ischemic stroke, it is worthwhile to investigate the variables that influence the levels of these cells. It is possible that these variables have prognostic and therapeutic consequences. Inhibitors,research,lifescience,medical In our study we did not observe an influence of aging or vascular risk factors on EPC counts. Only patients who received prior treatment with statins and specific etiologies were significantly associated with EPC counts. A direct comparison of our study with previous studies is

not possible for several reasons: statin pretreatment was not included as Inhibitors,research,lifescience,medical a variable (Ghani et al. 2005; Chu et al. 2008; Zhou et al. 2009); etiology subtype was not analyzed (Ghani et al. 2005; Inhibitors,research,lifescience,medical Yip et al. 2008; Zhou et al. 2009); the time from stroke onset to time of blood sampling were not restricted to the acute stage (Chu et al. 2008) or was not provided (Ghani et al. 2005); and the number of recruited patients was relatively small (Ghani et al. 2005; Chu

et al. 2008; Inhibitors,research,lifescience,medical Cesari et al. 2009). Additionally, some studies used flow cytometry (Yip et al. 2008; Cesari et al. 2009; Zhou et al. 2009) while others relied on counting colony-forming units (Ghani et al. 2005; Chu et al. 2008). Also, the definition of EPC was variable among the studies (Ghani et al. 2005; Chu et al. 2008; Yip et al. 2008; Zhou et al. 2009). To our knowledge, our study is the largest Inhibitors,research,lifescience,medical to date and the only one that analyzed serial samples at the acute, subacute, and chronic stage of stroke. Statins have several effects that are beneficial for patients with acute ischemic stroke, and are independent of the lipid-lowering properties (Marti-Fabregas et al. 2004). These effects may be mediated by the increase in the mobilization and the improvement of the functional activity of the EPC population, Batimastat that has been demonstrated in vitro and in patients with stable ischemic heart kinase inhibitor Oligomycin A disease (Vasa et al. 2001; Urbich and Dimmeler 2004). Thus, this influence of statins is likely a novel pleiotropic selleck Abiraterone effect. The administration of statins to patients with stable CAD increases the number of EPC (Vasa et al. 2001), but these results were not replicated in patients with chronic stroke (Mohammad et al. 2010). Recently, a study in patients with acute ischemic stroke reported that statin treatment for 4 days may increase circulating EPC levels (Sobrino et al. 2012b).

2006; Takenaga et al. 2009). Rats on day 7 or 28 after the embolism were sacrificed by decapitation, and their whole ipsilateral Palbociclib hemisphere was homogenized in ice-cold 15 mmol/L 2-(4-2[-hydroxyethyl]-1-pioperazinyl)-ethanesulphonic acid (HEPES), pH 7.4, containing 147 mmol/L NaCl, 4 mmol/L KCl, 3 mmol/L CaCl2, and 1.2 mmol/L MgCl2 (physiological buffer). The homogenate was centrifuged at 3500g for 10 min at 4°C, and Inhibitors,research,lifescience,medical the resulting pellet was resuspended in physiological buffer containing 20% Ficoll T-400 (Sigma) and then homogenized. After centrifugation at 25,000g for 10 min at 4°C,

the pellet was resuspended in 15% dextran T-500 (Sigma). The suspension was then layered onto 20% dextran T-500 Inhibitors,research,lifescience,medical and centrifuged at 25,000g for 10 min at 4°C. The pellet was finally resuspended in physiological buffer and used as the brain capillaries. Immunoblotting Western blotting was performed according to standard protocols. The following primary antibodies were used: rabbit polyclonal antibodies against Ang-1 (Abcam, Minneapolis, MN), Ang-2 (Abcam), Occludin (Life Technologies), ZO-1 (Zymed), Tie2 (Santa Cruz Biotechnology, Inc., Santa Cruz, CA),

VEGF (R&D Systems, Inc., McKinley Place, MN), and VEGFR2 (Abcam). Subsequently, the membrane was washed and Inhibitors,research,lifescience,medical incubated with secondary antibody. Bound antibody was detected by use of the enhanced chemiluminescence method (Amersham). Quantification was carried out by performing computerized densitometry with an image analyzer (ATTO Co., Tokyo, Japan). To minimize blot variability, we applied an aliquot of pooled “control” homogenate, which was obtained from naïve control rats, to one Inhibitors,research,lifescience,medical lane

of every gel and calculated the band intensity of immunoblotted samples relative to this standard. Statistical analysis The results were expressed as the means ± standard error of the mean (SEM). Differences between two groups were evaluated statistically by use of the unpaired Student’s t-test. Statistical comparison among Inhibitors,research,lifescience,medical multiple groups was made by performing analysis of variance, followed by Scheffe’s test as a post hoc test or repeated-measures Cilengitide analysis of variance. P-values of less than 0.05 were considered significant. Results Characterization of neural progenitor cells Figure 1A shows that cells in the neurospheres expressed the neural progenitor marker musashi-1 on day 6 when cultured in vitro. After triggering in vitro differentiation by withdrawal of the growth factors, we confirmed the tripotent nature of the NPCs by their ability to generate differentiated cells expressing neuronal (MAP2), astrocytic (GFAP), and oligodendrocytic (RIP) markers (Fig. 1B). Figure 1 Characterization of neural progenitor cells. (A) Triple staining with green-fluorescent protein (GFP), musashi-1, and 4′,6-diamidino-2-phenylindole (DAPI) was merged and Nilotinib CAS indicated that cells in neurospheres, which were prepared from gestational …

OS differs by somatic mutation status regardless of treatment

received: BRAF mutant, 8.8 months; KRAS mutant, 14.4 months and KRAS WT, 20.1 months (40). BRAF V600E mutation indicated poor prognosis in patients with KRAS WT disease in FOLFIRI alone and FOLFIRI/CTX groups; those with BRAF http://www.selleckchem.com/products/ldk378.html mutations had worse outcomes. BRAF V600E mutations were detected in 6% of tumor samples. In nearly all cases, these mutations were identified in KRAS WT tumors and the Inhibitors,research,lifescience,medical impact of BRAF mutation in relation to efficacy of anti-EGFR was examined in the CRYSTAL trial population. The presence of BRAF mutation was a poor predictor of response and survival. Whether this biomarker is a negative predictor in relation to CTX is difficult to determine since this trial had a relatively small number of patients with BRAF mutations (6). In other Inhibitors,research,lifescience,medical trials, tumor with BRAF mutation was a negative prognostic marker for OS in patients with mCRC (41,42). In the NORDIC VII population, patients with mutated BRAF had low RR and markedly shorter PFS and OS compared to WT

mutations (43). In a retrospectively analyzed study for endpoints of RR, time to progression, OS, and the mutational status of KRAS and BRAF, 113 tumors from CTX or PAM-treated mCRC patients were analyzed. The BRAF V600E mutation was detected in 14% of patients who had KRAS WT disease. None of the BRAF-mutated patients responded to anti-EGFR treatment and Inhibitors,research,lifescience,medical had significantly shorter PFS and OS compared to BRAF WT. The role of BRAF mutations in patients treated with EGFR-targeted drugs is similar to that of mutated KRAS

Inhibitors,research,lifescience,medical (44). Furthermore, 50% of BRAF mutations are more frequently detected in microsatellite instability (MSI-high) CRC compared with microsatellite-stable 12% (45-47). Even with BRAF inhibition by vemurafenib, limited response has been defined. It is proposed Inhibitors,research,lifescience,medical that with this inhibition, more activation of the EGFR will result unlike melanoma cells which express low levels of EGFR on the cell surface (48-52). A Dasatinib cell-based analysis of a trial adding sorafenib to an anti-EGFR agent showed that even BRAF-mutated CRC cells can potentially respond to EGFR-targeted therapy if the BRAF inhibitor, sorafenib, is administered concomitantly with CTX or PAM even when either drug alone has limited activity. These data indicate that in BRAF-mutated tumors, the therapeutic effect of CTX or PAM could be restored by an approach aimed at blocking Anacetrapib the EGFR pathway at multiple locations. In addition to sorafenib, other compounds targeting either BRAF (PLX4032) or its downstream effectors (ARRY-162, AZD6244, and PD0325901) are in clinical development and could be exploited in combination with EGFR-targeted moAb therapy (53,54). Despite KRAS and BRAF WT status, there have still been a significant percentage of non-responders (41%) to anti-EGFR therapy questioning further pathways that are important in defining resistance to these treatments (44).

In contrast, activation of MSNs associated with the direct pathway should decrease basal ganglia, output by directly suppressing activity at the level of GPi/SNr. Given the reentrant nature of basal ganglia-thalamocortical connections, cortically initiated activation of the direct pathway should therefore result, in positive feedback at cortical levels, due to thalamic disinhibition. Conversely, cortically initiated activation of the indirect pathway should have the opposite effect, due to the polarity-reversing effects of an intercalated stage of processing within GABAergic Inhibitors,research,lifescience,medical GPe. The direct, and indirect pathways differ sharply in their connections with the intralaminar thalamus. The basal ganglia output nuclei, GPi

and SNr, send GABAergic pallidothalamic and nigrothalamic projections to the centromedian (CM) and parafascicular (Pf) nuclei, respectively, as well as to the corresponding pallidal and nigral target zones in the ventrolateral or “motor” thalamus.264,274 Thalamostriatal projections from CM innervate the postcommissural (sensorimotor) putamen, while those from Pf are Inhibitors,research,lifescience,medical directed to the precommissural (associative) putamen, Inhibitors,research,lifescience,medical caudate sellectchem nucleus, and ventral striatum.261 The

projections from CM to putamen show considerable selectivity in their terminal ramifications. They both maintain strict topographical mappings that link corresponding thalamostriatal, striatopallidal, and pallidothalamic projection zones in CM, putamen, and GPi, respectively.261 Moreover, thalamostriatal axons of CM neurons terminate almost exclusively on the spines Inhibitors,research,lifescience,medical and dendrites of putaminal MSNs that project, to GPi, while avoiding those that project to GPe.253 The neuromodulatory effects of DA on the integrative activity of striatal MSNs differ considerably for the direct and indirect pathways, due to the dissimilar Inhibitors,research,lifescience,medical distributions of d1-like and d2-like receptors on the two types of MSNs.227,270 Multiple studies have shown that substance

Pcontaining, GPi/SNr-projecting striatal neurons of the direct, pathway express a preponderance of di-like receptors, while enkephalin-containing, GPe-projecting neurons of the indirect pathway express a higher proportion of d2like receptors227,275-277 despite variable degrees of colocalization of the two receptor types among a subset, of each of the two categories of striatal projection neurons.278 The direct- and indirect-projecting MSNs also differ with respect to their responses to ACh, due Batimastat to differences in the muscarinic receptors they express. Both types of MSNs express m1 receptors to comparable degrees.224 However, m4 receptors are expressed predominantly by the substance P-containing neurons of the direct pathway.279 Like the DA receptors, muscarinic receptors belong to the A family of seven-transmembrane receptors, and the G-protein to which the m4 receptor is coupled acts to decrease cAMP levels, making its ncuromodulatory effect, analogous to that of d2-like receptors.

The primary endpoint was change from baseline to the end kinase inhibitors of week 12 in the 6-minute walk distance (6MWD). Secondary endpoints included pulmonary vascular resistance changes, N-terminal prohormone brain-type natriuretic peptide (NT-proBNP), WHO functional class, time to clinical worsening, Borg scores, EuroQoL 5-dimensional Classification Component scores, and Living with Pulmonary Hypertension scores. At week 12, 6MWD had increased from baseline by a mean of 30 m

in the 2.5 mg–maximum group and had decreased by a mean of 6 m in the placebo group (least-squares mean difference, 36 m; 95% confidence interval: 20 to 52; P < 0.001). Significant benefits were seen in the 2.5 mg–maximum group, as compared with the placebo group, with respect to a range of secondary end points including pulmonary vascular resistance (P < 0.001), NT-proBNP (P < 0.001), WHO functional class (p = 0.003), time to clinical worsening (p = 0.005), and score on the Borg dyspnea scale (p = 0.002). Notably, patients who were receiving endothelin-receptor antagonists or non-intravenous prostanoids were permitted into the study and, accordingly, half

of patients were on background therapy for PAH: 44% with endothelin-receptor antagonists and 6% with nonintravenous prostanoids. Pre-specified subgroup analysis showed that riociguat improved the 6MWD in patients who had not received other PAH-targeted therapies and also in those who had been on endothelin-receptor

antagonists or prostanoids. Concerning the safety profile, riociguat was well tolerated with a discontinuation rate of 3% in the 2.5 mg–maximum group versus 7% in the placebo group. Syncope occurred less frequently in the 2.5-mg maximum (1%) compared to placebo (4%). The 2.5 mg maximum group had increased rates of hypotension (10%) and anemia (8%) compared to placebo group (2% for each), though without statistical significance. What have we learned? Both PDE-5 inhibitors and sGS stimulants target the NO-sGC-cGMP pathway. From a mechanistic point of view, sGC stimulators may have several advantages over PDE-5 inhibitors: [3] The therapeutic action of PDE-5 inhibitors is dependent on baseline NO availability (which is typically reduced in PAH). 13 In contrast, owing to its NO-independent mode of action, sGC stimulators are effective even when NO production is markedly reduced. [4] PDE-5 inhibitors Dacomitinib acts by prevention of cGMP degradation; accordingly in diseases where cGMP levels are low (as in PAH), the effectiveness of PDE-5 inhibitors is expected to be markedly limited. Furthermore, when PDE-5 is inhibited, the activity of other PDEs may compensate for it. [5] In PAH, sGC is upregulated in small pulmonary arteries 15 (as a compensatory mechanism) with increased opportunity for enhanced therapeutic actions of sGC stimulants.

As indicated before, the main reason for the deviations is most probably the variation in the yield biomass/glucose and the choice of simple rate laws. Table 5 summarizes the simulated and the experimental data for growth rate and the two uptake rates. Plot B in Figure 8

shows the relationship between PtsG and the degree of phosphorylation of EIIA. Table 5 Summary of the simulation results. Comparison between measured quantities and simulated quantities for experiments 1–7. First column: growth rate μ. μ is given in 1/h. Second and third columns: uptake rates via non-PTS download catalog system and … 2.5. Discussion Inhibitors,research,lifescience,medical Mathematical modeling can be a powerful tool to analyze systems that are hardly observable. Here, we use a simple core model for glycolysis of E. coli to predict semi-quantitatively the steady state behavior for central metabolites in dependence Inhibitors,research,lifescience,medical on the growth rate (for downloading all files

and comments see information given in the Appendix). Glycolysis is an important reaction system since some of the metabolites such as fructose-1,6-bisphosphate, PEP and pyruvate are closely related to signalling units that trigger the important transcription factors FruR and Crp. While experimental data for metabolite concentrations [19] and mathematical models [18] are available for specific situations—normally Inhibitors,research,lifescience,medical covering one single growth rate—meantime complete data sets for a broad range of growth rates are scarce. More complete models for central Inhibitors,research,lifescience,medical metabolsim were presented [20,21], however, a quantitative comparison with experimental data is missing. Therefore, these models are not suited

for a fair comparison. In [22] a detailed mathematical model similar to a model published by us [14] was presented but failed to predict genetic modifications. A comparison of modeling approaches and a presentation of the current “state of the art” on this topic can be found in [23]. To summarize, mathematical models to describe carbohydrate uptake and metabolism are available, but fail in reproducing experimental data or fail in predicting new experiments. In previous studies, Inhibitors,research,lifescience,medical we already analyzed the input/output relationship to describe a characteristic curve that relates growth rate for a number of carbohydrates Drug_discovery and the degree of phosphorylation of EIIA, an important metabolite of the PTS. Other groups focus on structural properties of the same system [10] or on the relationship between control, metabolites and fluxes through the system [20]. In this study, new experimental data is presented to extend our current model by taking into account the transcription factor activities, and experiments that are designed to modify the already available input/output characteristic curves in such a way that kinetic parameters can be estimated with higher accuracy are performed. Here, a strain is used that allows adjusting the level of the main glucose uptake system, namely PtsG, with IPTG as inducer.

In one of the earliest works involving concrete damage detection using the intensity modulation technique, Rossi and Le Maou [27] conducted experiments with a bare fiber for crack detection in concrete structures. The fiber, with its protective coatings removed, was embedded directly in the concrete, and the transmitted signal was monitored. As the crack reached to the fiber, the fiber broke, causing abrupt cessation of the transmitting signal. Although the simplest, the major limitation of this method is that once the fiber breaks no further detection can be performed. Ansari and Navalurkar [28] designed their sensors for crack detection based on the same intensity modulation method yet with a different configuration. To increase the sensitivity, the fiber was made in a loop shape such that the fiber circumferences the generated crack. The sensor based on this design is limited to small size cracks only. Leung et al. [29] developed a sensor to monitor flexural cracks in the concrete structures. The loss in the back scattered light intensity is related to a mechanical deformation. The arrangement of the fiber which is laid in a zig-zag course inside the concrete is the key feature of this design. This design increases the sensitivity of the system. The sensor is efficient in monitoring flexural cracks under various types of loads. This technique is simple and sensitive, but only responsive to certain orientations of cracks with regard to the fiber’s orientation. Habel et al. [30] demonstrated that an intensity-based FOS can be used in a quasi-distributed configuration to measure crack opening widths. Similarly, Lee et al. [31] showed that even a low resolution and less sensitive intensity based optical fiber sensor constructed with inexpensive instruments can be useful in the cases where precise measurements of strain or cracks are not required, for example, measurements of stiffness.In general, for health monitoring of concrete structures, including damage detection, an ideal technique should have the common desirables: a simple sensing mechanism, a long sensing range, low instrumentation cost, high sensitivity, fast response, insensitive to temperature and light fluctuations, and capability of distributed sensing [32]. In the present work, we describe a new fiber loop ringdown (FLRD) sensor, which potentially meets the aforementioned requirements for crack detection in concrete structures.The FLRD technique originates from cavity ringdown spectroscopy (CRDS). In CRDS, a light pulse is injected into a cavity constructed using two highly reflective mirrors. The trapped light pulse bounces back and forth many times before it dies out completely. In each round trip a small part of the light energy of the trapped light pulse leaks out of the cavity.