Virulence factors such as elastase and protease have been proposed to play an

important role in the Selleckchem Palbociclib initial establishment of lung infections (Elsheikh et al., 1987; Smith et al., 2006b) and are also important in acute infections, such as keratitis (Wilcox et al., 2008). These virulence factors have as well been shown to be present at elevated levels during acute exacerbations in patients with CF (Grimwood et al., 1993; Jaffar-Bandjee et al., 1995). In contrast, reduced expression of these virulence factors is associated with chronic CF isolates (Smith et al., 2006a; Tingpej et al., 2007; Bjarnsholt et al., 2010). It was observed here that the STY variants of strain 18A showed a dramatic increase in elastase activity and thus appear to regain hallmarks of acute infection isolates. This suggests that the expression of such virulence factors and the switch between acute and chronic infection types may be a reversible process. Moreover, strain 18A variants showed an increase in the production of acylated homoserine lactones, further showing that the loss of such phenotypes

by chronic infection isolates is reversible. The ability of P. aeruginosa to convert back to an acute infection phenotype may also explain the development of acute exacerbations during lung infection in patients with CF (Grimwood et al., 1993; Jaffar-Bandjee et al., 1995). The morphotypic and phenotypic variants studied here were stable, indicating that the morphotypic conversion was linked to a mutation. To better understand the processes driving the development of these variants, the mutation frequencies of AZD6738 cost the parental strains were investigated and the 18A parent strain was shown to have a 3.4-fold higher mutation frequency than strain PAO1. The lower mutation frequency observed for PAO1 may reflect differences in long-term selection, based on laboratory cultivation on defined media, compared to the lung environment with constant exposure to the host immune response, antibiotic challenge and invading strains. The mutation frequencies were determined at multiple stages of biofilm development for both strain Niclosamide 18A and strain PAO1, and it was observed that they fluctuated approximately

10- and 4.5-fold, respectively. The mutation frequencies also correlated with the growth phases of the biofilms (Fig. 5 and data not shown) with a decline in the mutation frequency when the biofilm biomass was increasing. Interestingly, Garcia-Castillo et al. (2011) have reported that biofilm populations of CF isolates showed a lower mutation frequency compared to planktonic cultures. In contrast, Conibear et al. (2009) demonstrated a 100-fold increase in mutation in biofilm cells, specifically within microcolonies, compared to planktonic cells. The biofilm populations studied [(our study) vs. subpopulations (Conibear et al., 2009)] could account for the differing findings. To explore further this generation of diversity, a number of genes that might contribute were subsequently sequenced.

These data suggest that CD3−CD16+CD8α+ NK cells dominate in the selleck chemical peripheral blood of chimpanzees, and that while there are indeed CD8α− NK cells, most of the CD3–CD16+CD8α+ cells in the study by Rutjens et al. 4 were in fact mDCs. A similar phenomenon may complicate interpretation of CD3−CD16+CD56− cells classified as NK cells in human studies 5, 9. In Rutjens et al. 4, the authors found that, unlike

CD8α+ NK cells, most putative CD8α− NK cells were nonresponsive to the classical NK stimulus, K562 cells, thereby leading the authors to the conclusion that CD8α− NK cells were in fact anergic. However, based on the evidence presented in Fig. 1 of this manuscript, most of the CD8α− cells are likely to be mDCs, explaining their perceived anergy. Therefore, we sought to functionally

confirm our phenotypic definitions by addressing responsiveness of each of the three CD16+ cell populations (Fig. 1) to the mDC stimulus, poly I:C; an NK-cell stimulus, MHC-devoid 721.221 cells; and a universal mitogen, PMA/ionomycin. We first evaluated the production of IFN-γ, an antiviral cytokine commonly produced by activated NK cells (Fig. 2A). In response to PMA/ionomycin and 721.221 cells, populations I and II, but not population III, produced high levels of IFN-γ. We next evaluated production of TNF-α, which can be produced by both NK

cells and DCs 2, 10, 11 (Fig. 2B). Interestingly, populations I and II produced TNF-α in response to 721.221 cells and PMA/ionomycin, but not in response to poly PD0325901 I:C. Population III also produced TNF-α, but only in response to PMA/ionomycin and poly I:C, suggesting that while all three populations were competent producers of TNF-α, secretion was stimulus-specific. Finally, we evaluated production of IL-12, produced by activated mDCs 10, 12, and found that only population III produced detectable intracellular cytokine levels, and only in Atazanavir response to poly I:C or PMA/ionomycin (Fig. 2C). These data indicate that the putative mDCs (III) and NK-cell populations (I and II) had very distinct functional profiles, which corresponded to DC and NK-cell repertoires, respectively, both in regard to stimulus specificity and cytokine production. Thus, based on the phenotypic and functional analyses presented here, it is clear that the CD3−CD16+CD8α− cell population in chimpanzee peripheral blood contains a small NK-cell subpopulation but is dominated by mDCs. Accurate identification of NK cells in both humans and nonhuman primates has been plagued by erroneous phenotypic and functional definitions, issues compounded by the lack of a single highly specific NK-cell surface marker in primates. The data published by Rutjens et al.

Gems are the sites of the maturation of spliceosomes, which are https://www.selleckchem.com/products/z-ietd-fmk.html composed of uridylate-rich (U) snRNAs (small nuclear RNAs) and protein complex, small nuclear ribonuclearprotein (snRNP). Spliceosomes regulate the splicing of pre-mRNA and are classified into the major or minor classes, according to the consensus sequence

of acceptor and donor sites of pre-mRNA splicing. Although the major class of spliceosomes regulates most pre-mRNA splicing, minor spliceosomes also play an important role in regulating the splicing or global speed of pre-mRNA processing. A mouse model of spinal muscular atrophy, in which the number of Gems is decreased, shows fewer subsets U snRNAs. Interestingly, in the central nervous system, U snRNAs belonging to the minor spliceosomes are markedly reduced. In ALS, the U12 snRNA is decreased only in the tissue affected by ALS and not in other tissues. Although the molecular mechanisms underlying the decreased U12 snRNA resulting in cell dysfunction and cell death in motor neuron diseases remain unclear, these findings

suggest that the disturbance of nuclear bodies and minor splicing may underlie the common molecular pathogenesis of motor neuron diseases. Motor neuron system selectivity is a major mystery of motor neuron diseases. Although research has shown that the pathology is not restricted to motor neurons but also extends into other www.selleckchem.com/CDK.html neurons as well as glial cells, the selective vulnerability of motor neurons is a characteristic feature of amyotrophic lateral sclerosis (ALS). However, the molecular mechanism underlying the vulnerability of the motor neuron system has not been fully explained. To clarify this issue, researchers must clarify what distinguishes the motor neuron. Researchers have identified several molecular markers and physiological characters that distinguish motor neurons from others.[1] However, the morphology and location of the cell have been used as the most significant signature for identifying motor neurons in tissues. The

cells of the CNS are diverse and complex, and they are mostly defined by their shape, size oxyclozanide and location in the tissues. The complexity of the cells reflects the complexity of the cells’ RNAs. The diversity of RNAs results in part from the methylation of DNA, but studies have shown that other mechanisms also control cell-specific RNA diversity. A higher structure of the nucleus, chromatin, and nuclear bodies, is another mechanism that regulates the cell-specific RNA diversity. Recent findings have revealed that chromatin has a unique structure and location in the nucleus in each type of cell. The chromatin structure is strongly associated with the diversity of RNA.[2] Moreover, the other intranuclear structures also play an important role in maintaining cell function and cell survival. Thus, the intracellular location or character of nuclear bodies may also differ in each cell type.

The

wells of 96-well Nunc-immuno plates click here (Nunc, Roskilde, Denmark) were coated with serial two-fold dilutions of antigen at 4°C overnight and then treated with 5% skim milk at 37°C for 1 hr to block nonspecific reactions. After washing five times, antigen was detected by anti-N MAb 13-27 and anti-G Mab 15-13, 13-13 and 15-10 (20). Following an additional five washes, horseradish peroxidase-conjugated anti-mouse IgG (Cappel, West Chester, PA, USA) was added to each well and incubated as above. After a final wash, the reaction was visualized with o-phenylenediamine (Sigma fast o-phenylenediamine dihydrochloride tablet sets, Sigma, St Louis, MO, USA) and stopped with H2SO4. The resulting OD490 was measured on a Model 559 Microplate Reader (Bio-Rad, Hercules, CA, USA). Monolayer cultures of NA cells were infected with each virus at a MOI of 0.01. After adsorption of virus for 1 hr, the cells were washed twice with Hank’s solution. Then fresh medium was added and the cells were incubated at 37°C. The culture media and cells were harvested at 1, 3 and 5 dpi. The virus in each sample was titrated in NA cells by focus assay as described above. For staining of viral foci, an IFA was performed using MAb 13-27 and FITC-conjugated rabbit IgG

to mouse IgG (Cappel). NA cells grown in 24-well culture plates were incubated with each virus JNK phosphorylation at 150 FFU per well for various time periods (15, 30 and 60 min). Following washing of the cells, medium-0.5% methylcellulose mix was added and the cells were incubated at 37°C. After 2 days, cells were fixed by 4% paraformaldehyde and then permeabilized with methanol, followed by IFA as described above. Efficiency of internalization of each strain is indicated as relative focus number considering focus number at 60 min as 1. Cell-to-cell spread of each strain was examined by using NA cells grown on 24-well culture plates (Greiner Bio-one, Frickenhausen, Germany). The monolayer cells were infected with each strain at 50 FFU per well and incubated for 1 hr at 37°C. After removal of the inoculums, the cells were washed with Hanks’ solution.

A medium-0.5% methylcellulose mix was added to each well and the cells for incubated at 37°C. After 48 and 72 hpi, the cells were fixed with 4% paraformaldehyde and then permeabilized with methanol. For staining of viral foci, an IFA was performed as described above. Photographs were taken with the Axiovert 200 or BZ-8000 digital microscope. Focus area was measured by Image J software (public software, http://rsbweb.nih.gov/ij/). Student’s t-test was applied for statistical analysis and P < 0.05 was considered to be statistically significant. We examined and compared the distribution of RC-HL strain- and R(G 242/255/268) strain-infected cells in the mouse brains by immunostaining for viral N protein. RC-HL strain-infected cells were found only in the hippocampi of the infected mouse brains (Figs 2a-2 and 2b-4 to 6).

The stained cells were washed with saponin buffer twice, suspended in isoflow, and analysed by flow cytometry. Production of LTB4 was analysed in the supernatants of CD11c+ cells purified from the lungs (1·5 × 105 cells/200 μl cultured for 18 hr) by enzyme-linked immunosorbent assay (ELISA) (IBL Internat.; IBL-America Minniapolis, MN). Differences between means

were analysed using Student’s t-test, and values of P < 0·05 were considered to indicate statistical significance. All calculations were performed with GraphPad Prism 4 for Windows buy Y-27632 (GraphPad Software; La Jolla, CA). Airway inflammation was induced in BALB/c mice by i.p. administration of OVA followed by challenge with aerosolized OVA, as described in the Materials and Methods.

Control mice were challenged with saline instead of OVA. Five days after the challenge with aerosolized OVA, we collected the BAL to confirm the development of the allergic process. This was confirmed by the high number of eosinophils found in the BAL of allergic mice (4·6 ± 2·3 × 105 cells/ml; eosinophil percentage 47 ± 9%) but not in control mice (2·8 ± 1·2 × 104 cells/ml; eosinophil percentage 2·3 ± 1·9%) [mean ± standard error of the mean (SEM), n = 6, P < 0·001, for allergic versus control mice]. Also revealing the development of the allergic status, we found high levels of serum IgE antibodies directed to OVA (Fig. 1a). DCs were differentiated from bone marrow precursors, as described in the Materials and Methods. Figure 1(b) shows the phenotype of these DCs, while Fig. 1c Histone Methyltransferase inhibitor shows that i.t. inoculated DCs effectively arrived to lung tissues 6 hr after inoculation. We then investigated whether i.t. inoculation of histamine-treated DCs pulsed with OVA was able to modulate lung infiltration by T cells in allergic mice. Airway inflammation was induced in BALB/c mice as described in the Materials and Methods. Histamine-treated DCs (DCHISs) were prepared by incubating DCs and histamine (1 μm) for 30 min at 37°. Then, either control DCs (DCs) or

DCHISs were pulsed with OVA (100 μg/ml) for 3 hr at 37° and, after washing, they were injected i.t. into BALB/c mice 3 days after OVA challenge. Control mice were inoculated i.t. with PBS instead of DCs. Lung tissues were collected in all cases 2 weeks later. Cell suspensions were obtained from the lungs after Baricitinib collagenase treatment, and T cells were purified by magnetic isolation, using a monoclonal antibody directed to CD3 coupled to magnetic beads (> 80% purity). The total number of T cells purified from the lungs was similar for mice inoculated with PBS, DCs or DCHISs (not shown). Interestingly, a significant increase in the percentage of CD8+ T cells was observed in T cells purified from the lungs of DCHIS-treated mice (Fig. 2a,b) compared with T cells from mice treated with either PBS or control DCs. No changes in the percentage of CD4+ T cells were detected (Fig. 2c,d). We then analysed the pattern of cytokine production by lung CD8+ T cells.

The authors would like to thank the people of 3-deazaneplanocin A price Um-Zukra village for their continuous cooperation. This study was supported by the Institute of Nuclear Medicine, Molecular Biology and Oncology, University of Gezira, Sudan. Our thanks are also due to the Ministry of Higher Education and Scientific Research for their partial financial support. “
“Thyroid disease is one of the most common endocrine conditions affecting women during reproductive age. A link between thyroid and assisted reproduction outcome is debated. Serum TSH levels, number and scoring of oocytes and embryos, and number of clinical pregnancies were retrospectively recorded

in 164 women undergoing assisted reproduction technologies (ART) at an University–based fertility center, to evaluate the outcome of the first steps of assisted reproduction (ovarian stimulation, oocyte pickup and fertilization, embryo transfer and implantation) in relation to thyroid function and autoimmunity. No significant relationship was found between TSH and all parameters, except clinical pregnancy rate (22.3% in TSH ≤ 2.5 group versus 8.9% in TSH > 2.5 mUI/L group; P = 0.045).

Cetuximab molecular weight No pregnancy occurred in women with anti-thyroperoxidase autoantibodies, while pregnancy occurred in 23.9% of cycles without autoimmunity (P = 0.02). Further studies must be conducted in order to shed light on the link between infertility and thyroid dysfunction. “
“The

mammalian target of rapamycin (mTOR) is a key regulator of cell growth and metabolism. It associates with multiple proteins and forms two distinct signaling complexes, mTORC1 and mTORC2. Accumulating evidence has revealed critical roles for intact mTOR signaling during T-cell activation and responses to microbial infection. However, the importance of mTOR regulation ioxilan in T cells has yet to be explored. The TSC1/TSC2 complex has been shown to inhibit mTORC1 signaling in cell line models. We show here that deletion of TSC1 in the murine T-cell lineage results in a dramatic reduction of the peripheral T-cell pool, correlating with increased cell death. While mTORC1 is constitutively activated, mTORC2 signaling, reflected by Akt phosphorylation and activity, is decreased in TSC1-deficient T cells. Furthermore, TSC1-deficient T cells contain elevated reactive oxygen species (ROS) and exhibit decreased mitochondrial content and membrane potential, which is correlated with the activation of the intrinsic death pathway. Overall, our results demonstrate that TSC1 differentially regulates mTORC1 and mTORC2 activity, promotes T-cell survival, and is critical for normal mitochondrial homeostasis in T cells. The induction of the adaptive immune response is, in part, characterized by the aggressive expansion of an antigen-specific T-cell pool, coincident with the production of cytokines by said population.

[37] CD38, a cellular activation marker previously associated with HIV pathogenesis,[38]

presented a higher frequency in CD8+ T cells among RR/HIV individuals in the NS and ML-stimulated cells, a phenomenon not detected in the RR group. A higher frequency of CD38 in HIV/leprosy co-infected individuals, regardless of the lower viral load, has also been found in recent studies.[39] This activation marker profile can be attributed to the remaining viral production that persists in certain patients whether they are undergoing effective, long-term HAART selleck inhibitor or not.[40] Furthermore, the increased frequency in T-cell activation markers in RR and RR/HIV might also be explained by the fact that immune activation could be determined by ML. As in recent

studies showing a higher frequency of CD8+ T cells in the borderline tuberculoid/HIV granuloma of HIV patients,[41] our data demonstrated a higher frequency of CD8+ T cells in RR/HIV granulomas. T-cell memory, a critical component of the adaptive immune Ivacaftor supplier response, is characterized by an increase in the strength and speed of the reaction against previously encountered pathogens. In recent studies evaluating immune responses in patients with tuberculous pleurisy, it was demonstrated that early secreted antigen target (ESAT)-6 and culture filtrate protein (CFP)-10-specific T helper type 1, type 22 and type 17 cells presented a CD45RA− CD62L− CCR7+ CD27+ phenotype.[42] In addition, the presence of a CFP-10-specific population with a CD45RO+ CD62L− CCR7− CD27− phenotype has been described in patients with tuberculous pleurisy.[43] In bacillus Calmette–Guérin-immunized purified protein derivative-positive patients, it was found that IFN-γ-producing CD4+ cells presented a CD45RA− CCR7+/− CD62L− phenotype, which indicates that these cells are central/effector memory cells.[44] In a longitudinal study investigating the effect of HAART in patients co-infected with HIV/M. tuberculosis, it was seen that the HAART effect leads to expansion of central memory CD27+ CD45RA−

and CD27+ CCR5− CD4+ cells after 12 weeks followed Carteolol HCl by expansion of naive CD27+ CD45RA+ cells after 36 weeks. Terminally differentiated effector CD4+ CD27− CCR7− cells decreased by 12 weeks together with a proportional decline of purified protein derivative-specific CD4+IFN-γ+ cells.[45] The present study also showed that ML increased the frequency of central memory CD4+ T and CD8+ T cells in RR patients. RR/HIV patients likewise presented an increase in TCM CD4+ T cells along with higher numbers of TCM and TEM CD8+ T cells. An augmentation in the number of CD8+ T cells co-localizing with CD45RA in skin biopsies was seen as well, which may be indicative of an effector memory phenotype.

Padlock probes targeting the ITS region were designed and were ordered from Invitrogen Inc. (Breda, the PR-171 ic50 Netherlands).

To optimise the binding efficiency to target DNAs, the padlock probes were designed with minimum secondary structure and with Tm of the 5′ end probe binding arm close to or above ligation temperature (63 °C, see below). To increase its discriminative specificity, the 3′ end binding arm was designed with a Tm 10–15 °C below ligation temperature. Linker regions of species-specific probes were taken from Zhou et al. [20] and 5′ and 3′ binding arms were designed in this article (Table 2). Oligonucleotide probes (Table 2) consisted of two adjacent complementary target sequences (12–26 bp) with a spacer region (63 bp) to facilitate loop formation and to provide a template for RCA primer binding. All primers and probes were synthesised by a commercial manufacturer (Invitrogen, Carlsbad,

CA, USA). One microlitre of ITS amplicon was mixed with 0.1 μl of ampligase (5 U μl−1), 2 nmol of padlock probe, 1 μl of 10× ligation buffer, 4.9 μl of water with a total reaction volume of 10 μl. Padlock probe ligation was conducted with one cycle of denaturation for 5 min at 95 °C, followed by seven cycles of 95 °C for 30 s and 4 min ligation at 63 °C. Exonucleolysis is required to remove unligated padlock probe and template PCR product and thus reduce subsequent ligation-independent amplification events. This step seems optional in previous works,[17] and we decided to delete this step without jeopardising AZD9668 speed and reliability of the method. Three microlitre of ligation product was used

as template for RCA. The total volume was 46 μl containing 1 μl Bst DNA polymerase LF (New England Biolabs, Hitchin, UK), 1 μl deoxynucleoside triphosphate mix (5 mmol l−1), 1.5 μl of 10 pmol of RCA primer each, 5 μl RCA buffer 10×, 36 μl water. Probe signals were amplified by incubation at 65 °C for 60 min, and accumulation of double stranded DNA products was visualised on a 1% agarose gel to verify the specificity of probe-template binding. Positive reactions showed a ladder-like pattern, whereas negative reactions showed a clean background. Smart DNA ladder (0.2–10 kb; Eurogentec, Seraing, Belgium) was used as molecular weight standard. To evaluate the detection limit of the RCA assay, two microlitres of each 10-fold serial dilution ADP ribosylation factor was used in each RCA reaction. ITS amplicons of R. arrhizus var. delemar CBS 395.54 was used (Fig. 2). The ITS alignment revealed suitable positions for the development of padlock probes distinguishing between six taxa tested in this study. All tested strains generated positive results with respective padlock probes. The duration of the RCA assay was 2 h. Positive responses proved to be 100% specific for all strains, species-specific probes correctly identifying all six species and varieties analysed. No cross reaction was observed between these taxa (Fig. 1). CBS 395.54, CBS 109939, CBS 109940, CBS 103.

The antibody

optical density values, background corrected, were then transformed and standardized into optical density indexes as: Xi = (OD test sample − OD negative control)/(OD positive control-OD negative control) where Xi represents a replicate for each individual at every sampling point (30,31). The average of the two replicates this website was then calculated for each individual at every sampling point, and the new standardized mean optical density indexes used for the statistical analyses. Linear mixed effect models (with restricted maximum likelihood, LME-REML) were used unless otherwise specified. To highlight differences

in the dynamics selleck inhibitor of infection compared to the controls, nematode abundance or immune variables (cytokines, blood cells, systemic and local antibodies), as response variable, were examined in relation to treatment (infected and control), time (days or weeks post-infection, DPI or WPI) or location of the infection (SI-1 to SI-4 or stomach top & bottom) as independent variables. The individual identification code (ID) was included as a random effect or/and as an autoregressive function of order 1 (AR-1) to take into account the nonindependent sampling of the same individual through time or the monitoring of different parts of the same organ from the same individual. To identify the combination of immunological variables Phosphoglycerate kinase that mainly affected parasite abundance, this analysis was repeated using parasite abundance as a response variable and immune variables as independent factors. The immune variables were initially selected through a principal component analysis (PCA singular value decomposition) based on the

infected individuals. Specifically, the multivariate association of different combinations of variables was examined, and the predictions from the combinations that explained most of the variance of the first and second principal components were then used for the linear mixed effect models. These analyses were performed for both T. retortaeformis and G. strigosum infections. Infection of rabbits with T. retortaeformis or G. strigosum led to the successful establishment of infective larvae (82% for T. retortaeformis at seven DPI and 44% for G. strigosum at 15 DPI) and subsequent development into adults (Figure 1).

“
“Please cite this paper as: Nunes, Krishnan, Gerard, Dale, Maddie, Benton and Hoying (2010). Angiogenic Potential of Microvessel Fragments is Independent of the Tissue of Origin and

can be Influenced by the Cellular Composition of the Implants. Microcirculation17(7), 557–567. We have demonstrated that MFs isolated from adipose retain angiogenic potential in vitro and form a mature, perfused network when implanted. However, adipose-derived click here microvessels are rich in provascularizing cells that could uniquely drive neovascularization in adipose-derived MFs implants. Objective:  Investigate the ability of MFs from a different vascular bed to recapitulate adipose-derived microvessel angiogenesis and network formation and analyze adipose-derived vessel plasticity by assessing whether vessel function CDK inhibitor could be modulated by astrocyte-like cells. Methods:  MFs were isolated by limited collagenase digestion from rodent brain or adipose and assembled into 3D collagen gels in the presence or absence of GRPs. The resulting

neovasculatures that formed following implantation were assessed by measuring 3D vascularity and vessel permeability to small and large molecular tracers. Results:  Similar to adipose-derived MFs, brain-derived MFs can sprout and form a perfused neovascular network when implanted. Furthermore, when co-implanted in the constructs, GRPs caused adipose-derived vessels to express the brain endothelial marker glucose transporter-1 and to significantly reduce microvessel permeability. Conclusion:  Neovascularization involving isolated microvessel elements is independent of the tissue origin and degree of vessel specialization. In addition, adipose-derived vessels have the ability to respond to environmental signals and change vessel characteristics. “
“Please cite this paper as: Roustit and Cracowski (2012). Non-invasive Assessment of Skin Microvascular Function in Humans:

An Insight Into Methods. Microcirculation 19(1), 47–64. For more than two decades, oxyclozanide methods for the non-invasive exploration of cutaneous microcirculation have been mainly based on optical microscopy and laser Doppler techniques. In this review, we discuss the advantages and drawbacks of these techniques. Although optical microscopy-derived techniques, such as nailfold videocapillaroscopy, have found clinical applications, they mainly provide morphological information about the microvessels. Laser Doppler techniques coupled with reactivity tests are widespread in the field of microvascular function research, but many technical issues need to be taken into account when performing these tests. Post-occlusive reactive hyperemia and local thermal hyperemia have been shown to be reliable tests, although their underlying mechanisms are not yet fully understood.