Now showing items 4010-4029 of 39116

    • C-3 AND C-4 PHOTOSYNTHESIS, COMPETITION, AND THE LIMITS TO GRASS SPECIES DISTRIBUTIONS IN AN ARIZONA GRASSLAND.

      Schaffer, William M.; GUREVITCH, JESSICA. (The University of Arizona., 1982)
      In a warm, dry grassland in southeastern Arizona dominated by C₄ grasses the only C₃ grass found was restricted to dry, exposed ridge crests within the hottest and driest part of the region. This was precisely the opposite of what one would predict from physiological and biogeographic considerations, which would lead one to expect a C₃ grass in this environment to be growing on cooler or moister areas that would mitigate the effects of the inhospitable climate. Cover of C₄ grasses was very low on these ridge crests, and increased downslope with the greater volume of water available to high values on the lower slopes and in washes. It was suggested that this C₃ grass, Stipa neomexicana, had a very high tolerance of water stress, but a very poor tolerance of competition, and was limited to unfavorably dry sites by its competitively superior C₄ neighbors. Most species, regardless of photosynthetic type, could not survive in the harsh ridge crest environment, which therefore offered a refuge from competition. The hypothesis of competitive exclusion was tested by removal experiments conducted at ridge crest, midslope and lower slope positions along the topographic gradient of decreasing Stipa neomexicana and increasing C₄ grass cover. The predictions made under this hypothesis were confirmed. The presence of competitors limited the growth of mature plants, flower production, seedling establishment and seedling survival. The beneficial effects of the removal of competitors increased downslope. Competition depressed estimated finite rates of population increase for Stipa neomexicana. This depression was most severe on the lower slope. It was concluded that increasing competition from C₄ grasses along the topographic gradient was responsible for restricting Stipa neomexicana to the unfavorable ridge-crest sites.
    • The c-function for affine Kac-Moody algebras

      Pickrell, Doug; Dang, Son Xuan, 1964- (The University of Arizona., 1996)
      In this paper, we will first study the Harish-Chandra transform and the c-function for finite type Kac-Moody groups. The Harish-Chandra transform is essentially the Gelfand transform on L¹( K\G/K). From our point of view, the c-function arises as the Fourier transform of the diagonal distribution for Haar measures of K. A brief account of Kac-Moody algebras, especially affine Kac-Moody algebras, is also presented. Then we use a formula of Harish-Chandra for the c-function for finite type Kac-Moody groups to discuss the definition of the c-function for affine Kac-Moody algebras, especially the twisted affine Kac-Moody algebras. It turns out the c-function for an affine Kac-Moody algebra can be written as a product of trigonometric functions over the positive roots of the corresponding finite type Kac-Moody algebra. This finite type Kac-Moody algebra is the Lie algebra of a finite type Kac-Moody group G. Then the c-function can be thought as the Fourier transform of the diagonal distribution for a Haar type measure of G. For the affine Kac-Moody algebra of type A⁽¹⁾₁ , G is SL(2, C) and the measure is (trace(g* g))⁻³. This leads to the question of whether (trace( g* g))⁻ᵐ on SL(n, C) is that measure for the affine Kac-Moody algebra of type A⁽¹⁾(n-1). In the last part, for any positive integer l, the Harish-Chandra transform of (trace(g* g) ⁻⁽⁽ⁿ⁽ⁿ⁻¹⁾⁾/²⁾⁻¹ on SL(n, C) is calculated to check if the Fourier transform of the diagonal distribution for (trace(g* g) ⁻⁽⁽ⁿ⁽ⁿ⁻¹⁾⁾/²⁾⁻¹ is the c-function for the affine Kac-Moody algebra of type A⁽¹⁾(n-1).
    • The C-O-H-S gas system and its applications to terrestrial and extraterrestrial volcanism

      Gerlach, Terrance Melvin, 1941- (The University of Arizona., 1974)
    • C. ELEGANS RESPONSE TO COMBINED STRESS

      Sutphin, George; Furtmann, Amanda (The University of Arizona., 2020-05)
      Cellular stress has been shown to increase with age, but the human body’s ability to respond to this stress decreases with age. Various forms of stress, including osmotic and heavy metal stress, are linked to a broad range of human disease. Age is the leading risk factors for many of these major morbidities, including cardiovascular disease and cancer, among others. Developing a better understanding of stress response pathways will allow targeted therapy for better treatment. Developing a better understanding of stress response pathways will allow targeted therapy for better treatment. Using the roundworm Caenorhabditis elegans as a model of study, I investigated the osmotic and heavy metal stress pathways by treating worms with sodium chloride (NaCl) and cadmium chloride (CdCl2), respectively. I first identified a target dose for each stressors that reduced lifespan by 50%, then I combined the stressors in order to observe their interaction. I found that 250mM NaCl and 1mM CdCl2 reduced C. elegans lifespan by roughly 50% individually. When these two stressors were combined, I observed an 85% reduction in lifespan, indicating that the stressors are activating different responses within the worms.
    • The C.A.S.E. Approach (Corroboration, About Me, Science, Explain/Advise): Improving Communication with Vaccine-Hesitant Parents

      Peek, Gloanna; Stevens, Jessica Celeste; Peek, Gloanna; McArthur, Donna B.; Badger, Terry A. (The University of Arizona., 2016)
      OBJECTIVES: The anti-vaccination movement is prevalent in today's media with claims which continue to create feelings of fear and trepidation in the minds of many parents. The C.A.S.E. Approach (Corroboration, About Me, Science, Explain/Advise) is a method ofcommunication to be used in formulating meaningful, rapid responses to parents hesitant to vaccinating their children. This DNP project assessed the effects of a C.A.S.E. Approach learning module on family nurse practitioner (FNP) students' perceived levels of knowledge and self-efficacy regarding vaccination discussion with vaccine hesitant parents (VHPs). METHODS: This DNP project used a pretest-posttest design to measure the effects of the C.A.S.E. Approach training intervention on both knowledge and self-efficacy levels of FNP students. Fourteen students participated in this study. Each took the 20-question pretest C.A.S.E. Approach Questionnaire, then participated in the C.A.S.E. Approach learning module,and finished by repeating the questionnaire as a posttest following the intervention. The questionnaire was designed using four-item Likert questions scored 1 (strongly disagree) to 4(strongly agree), wherein higher scores reflected better understanding and self-efficacy in the C.A.S.E. Approach. Students were recruited via an online classroom format within a nursing course offered at the University of Arizona: Nursing 612, Introduction to Pediatrics. All testing and module information was accessed online and questionnaire responses were stored at Qualtrics.com, also online. RESULTS: Students' posttest scores following the intervention of the C.A.S.E. Approach learning module were significantly higher than pretest scores. Perceived knowledge (p< 0.001)of the C.A.S.E. Approach increased more significantly than did perceived self-efficacy (p =0.001) of the C.A.S.E. Approach following the module. Mean test scores increased on average 14.29 points in perceived knowledge of the C.A.S.E. Approach following the module, and 7.93 points for perceived self-efficacy following the module. CONCLUSION: Key findings included an observed increase in participating students' perceived knowledge regarding the C.A.S.E. Approach as well as an observed increase inparticipating students' perceived self-efficacy in using the C.A.S.E. Approach. There was strong statistical evidence (p≤0.05) to suggest the learning module increased student knowledge andself-efficacy regarding vaccine discussion.
    • C.P.E. Bach's "Rondos for Connoisseurs and Amateurs"

      Webb, Robin Timothy (The University of Arizona., 1984)
    • Ca2+/Calmodulin-Dependent Protein Kinases: Role In Excessive Cell Growth And Hypertension

      Cohen, Zoe; Carr, Shane Geary (The University of Arizona., 2019)
      Hypertension is a widespread disease with over one-third of all US citizens being afflicted. Hypertension significantly increases the likelihood of heart disease, which is the currently leading cause of death in the US. This paper reviews the factors that cause hypertension, such as increased cardiac output, increased stroke volume, increased vessel length, and decreased vessel radius. The second section delves into our research on how excessive pulmonary arterial smooth muscle cell (PASMC) proliferation contributes to hypertension. We observed that patients with idiopathic pulmonary arterial hypertension (IPAH) have increased cytosolic calcium concentration in their PASMCs. However, it is unknown how calcium plays a role in this increased proliferation. This study explores our hypothesis that the family of proteins Ca2+/Calmodulin-Dependent Protein Kinases (CaMK) may be the link between calcium and excessive cell proliferation. Our results found that two CaMK proteins, CaMKIV and CaMKII δ, cause increased proliferation and are found at higher concentrations in patients with IPAH. We found that these two CamK proteins are necessary for the increased activity of AKT and PDGFR, two proteins involved in the proliferation pathway. While more research is needed, these results suggest that CaMKIV and CaMKII δ could be targets for the treatment of hypertension.
    • Ca2+/CaM Modulates the Functional Effects of cMyBP-C on the Thin Filament

      Harris, Samantha P.; Yang, Yuanzhang; Harris, Samantha P.; Granzier, Hendrikus L.; Colson, Brett (The University of Arizona., 2017)
      Background. Cardiac myosin binding protein-C (cMyBP-C) is an essential regulator of heart muscle function that is necessary for both normal contraction and for increased contractility in response to inotropic stimuli(1-7). Effects of cMyBP-C on contraction are due to dynamic interactions of cMyBP-C with both actin and myosin, but the mechanism(s) by which cMyBP-C binding to these ligands is modulated are only partly understood. Recently, calmodulin (CaM) was shown to bind to cMyBP-C in the regulatory M-domain(8, 9) near a conserved actin binding site(10). Here we investigated whether CaM competes with actin for binding to cMyBP-C and thus whether CaM affects cMyBP-C function. Methods. Recombinant N’-terminal domains of cMyBP-C were used in pull-down assays, co-sedimentation binding assays, and actin activated myosin ATPase assays to determine effects of CaM binding on cMyBP-C. Results. In accordance with previous reports, we found that CaM binds to N’-terminal domains of cMyBP-C in the presence of Ca2+ (Ca2+/CaM) with a binding affinity comparable to cMyBP-C binding to actin (3-10 μM). We further show that Ca2+/CaM reduces cMyBP-C apparent binding affinity for actin, consistent with the competition between Ca2+/CaM and actin for binding to cMyBP-C. Ca2+/CaM also reversed the inhibitory effects of cMyBP-C N’-terminal domains on actin activated myosin ATPase rates, consistent with reduced cMyBP-C interactions with actin. However, apo-CaM (calcium-free calmodulin) did not influence the ability of cMyBP-C to activate actomyosin ATPase rates at low Ca2+. Phosphorylation of cMyBP-C by PKA significantly increased its binding to both Ca2+/CaM and apo-CaM. Phosphorylated cMyBP-C was also a less potent regulator of cross-bridge cycling in ATPase assays. Conclusions. These data demonstrate that Ca2+/CaM competes with actin for binding to cMyBP-C and selectively reverses the inhibitory effects of cMyBP-C on actomyosin interactions. However, apo-CaM does not compete with cMyBP-C binding to actin and does not affect the ability of cMyBP-C to activate the thin filament at low Ca2+. Ca2+/CaM may serve as additional regulatory mechanism in addition to phosphorylation of cMyBP-C to regulate its function. These data suggest that Ca2+/CaM is a novel modulator of cMyBP-C function that can dynamically tune cMyBP-C effects on contraction potentially as [Ca2+]i rises and falls during the time course of a single heart beat.
    • Cable-drawn farming system analysis and control development

      Coates, Wayne E.; Siemens, Mark Cornelius, 1965- (The University of Arizona., 1996)
      Four types of cable drawn farming systems, a single engine system, a double engine system, a perimeter system, and a double implement system, were analyzed to determine which was best suited for Arizona. The systems were compared in terms of relative cost, reliability/simplicity and field capacity. Field capacity computation variables were implement width, implement speed, tower travel speed, implement carrier travel speed, and implement rotation time. The analysis showed the single engine system was the least expensive, simplest system with a field capacity identical to that of the double engine system, eight percent lower than the double implement system, and approximately thirteen percent higher than the perimeter system. Based on these results, the single implement system was judged superior to the others. The parameters affecting single implement system performance were then examined to optimize performance. The evaluation yielded a recommendation that the system be designed to have a tower speed of 48 ft/min, and a rotation time of 7.5 seconds. A positioning system for the mobile truss of a cable drawn farming system was also developed and tested. The system used a linear move irrigation system's above ground cable guidance system for steering, a wicket positioning system for stopping the machine at the indexing locations, and a wire-alignment system to control inner tower alignment. The system was tested over a length of 280 ft using a five tower, 575 ft long, linear move irrigation system. It was found that the above ground cable guidance system provided ±0.5 ft steering accuracy, the wicket positioning system controlled the power unit and end tower position within ±0.2 ft of the target destination, and that the wire alignment system controlled inner tower position within ±0.3 ft of the target destination. Statistical analysis of the test results showed the probability of position error being controlled to within ±0.4 ft and ±0.8 ft to be at the 99.7% and 99.99% confidence levels, respectively.
    • The cadaver experience: The effects of self-esteem and denial on existential terror in medical students.

      Chatel, Daniel Mark.; Greenberg, Jeff; Fahey, Shirley; McCloskey, Laura (The University of Arizona., 1992)
      Eighty-four medical students at the University of Arizona were administered measures of self-esteem, medical attitudes, social desirability, purpose in life, satisfaction with life, state and trait anxiety one week before their first cadaver dissecting experience. On the day of the experience, half of the subjects completed these measures again in addition to a death anxiety scale just prior to their first cadaver exposure. The other half completed these measures immediately after their first cadaver exposure. Results found main effects of self-esteem with high self-esteem subjects endorsing higher purpose in life and medical attitudes and lower state anxiety and death anxiety. Time by condition interactions were found for state anxiety and purpose in life, with both significantly higher in subjects assessed following exposure to the cadaver. Finally, a main effect for condition was also seen with regard to fear of death, with those exposed to the cadaver scoring significantly higher. Implications with regard to terror management theory and medical education were discussed. In particular, the results tend to support the notion of self-esteem as a psychological buffer against the existential anxiety resulting from an awareness of mortality. Further, results also suggest that cadaver dissection is a powerful emotional experience for physicians in training, significantly affecting their attitudes and requiring sensitivity of medical educators to the psychological impact of cadaver dissection.
    • THE CADAVEROUS CITY: THE EVERYDAY LIFE OF THE DEAD IN MEXICO CITY, 1875-1930

      López, Amanda M.; Beezley, William H.; Barickman, Bert J.; Few, Martha; Gosner, Kevin (The University of Arizona., 2010)
      This dissertation explores burial practices and funeral rituals in Mexico City during the late-nineteenth and early-twentieth centuries. I argue that international shifts in ideas about public health, class, and nationalism were reflected in new spaces and practices for dead bodies. Furthermore, I examine how mass death challenged traditional burial practices. The daily practices involved in managing the disposal and veneration of dead bodies illuminate the social and cultural challenges in building modern cities and the ways in which these projects are adopted or rejected by the citizenry. The first three chapters focus on the modernization of burial practices in the nineteenth century. Burial reform laws in the 1850s led to the foundation of the capital's first large, modern cemetery, the Panteón de Dolores, by the Liberal government in 1879. The cemetery became a microcosm for the clean, modern city, mapping the new social class configuration through the distribution of its graves. Quickly the administrators of the Dolores Cemetery failed to meet ideal due to the realities of daily operation. The cemetery had been imagined as a space that reflected elite ideas of modernity, but it served a capital that was mostly indigent. In response to overcrowding, the technology of cremation, which targeted the poor, created a class division between those who could be buried and those who had to be cremated. Government officials successfully constructed a modern, sterile approach to death and began to wrest away control of the symbolic power of death from the Catholic Church. The last two chapters focus on the temporary breakdown of these practices and the reinterpretation of funeral rituals in the early twentieth century. Instability and high mortality rates during the Revolution of 1910-1920 led to overcrowding in cemeteries and spread the dead beyond the cemetery, including impromptu battlefield cremations. A comparison of three funerals in 1928-1929 shows new ways in which the funeral was used to perform ideas about the nation, family, and masculinity. The Revolution's unmanageable casualty levels and the advent modern, secular funerary practices in the period before the Revolution influenced how the government, military, and civilians handled and memorialized death.
    • Cadmium content in sphalerites, copper ores, soils and plants in southern Arizona

      Kresan, Peter Lawrence, 1948- (The University of Arizona., 1975)
    • Cadmium distribution in the rat after subacute exposure to cadmium in drinking water

      Brancato, David Joseph, 1950- (The University of Arizona., 1974)
    • Caesalpinia pulcherrima, Calliandra californica, and Justicia specigera: Chemical and environmental regulation of their growth and development

      Bailey, Douglas A.; Davison, Elizabeth L., 1947- (The University of Arizona., 1989)
      Investigations of three low-water requiring landscape species produced the following results: (1) Although Calliandra californica flowered under photoperiods from 12 to 16 hours, plants produced more elongation under 16 hour days. Plants grew taller and developed greener foliage under irradiances of 600 μmol·m⁻²·s⁻¹. Branching was not stimulated by foliar sprays of BA, PBA, or BA + GA₄₊₇. (2) Caesalpinia pulcherrima increased biomass under 16 hour days, but were stunted and chlorotic under irradiances of 1950 μmol·m⁻²·s⁻¹. Internodal lengths were restricted with drenches of 3.75 mg · pot-1 uniconazole, and plants sprayed with 500 mg·liter⁻¹ PBA developed more axillary branching without negative elongating effects. (3) Justicia specigera gained more height under 12 hour days, and produced greener foliage, more elongation, and faster flowering under irradiances of 600 μmol·m⁻²·s⁻¹. Plants showed restricted internodal elongation and fewer flowers when drenched with 5.0 mg·pot⁻¹ uniconazole, and developed more axillary branching with no detrimental elongation effects when sprayed with 100 mg·liter⁻¹ BA + GA₄₊₇.
    • Caffeine consumption and symptom severity among midlife Filipina Americans

      Berg, Judith A.; Zitzmann, Lori Jean (The University of Arizona., 2000)
      Caffeine has diverse effects on human physiology. Certain symptoms associated with caffeine consumption are similar to those reported by some women during midlife. Lifestyle factors such as caffeine consumption must be viewed within the context of culture and ethnicity. The Neuman Systems Model provided the theoretical framework for this secondary data analysis. A descriptive cross-sectional survey design was used to examine questions related to study variables. A cluster of symptoms (fatigue, palpitations, insomnia, GI distress) were described through the lens of both perimenopausal transition and caffeine consumption for a sample of 160 midlife Filipina Americans. No significant relationship was found between specific symptoms and symptom clusters and either caffeine consumption or perimenopausal status. Midlife Filipina Americans consume caffeine in low amounts and report mi nimal to mild symptom severity most often. Knowledge gained from this study may be applied to other groups to maintain congruency with ethnicity of clients.
    • CAGE-SIZE, GENDER AND MEASUREMENT ISSUES IN THE STUDY OF MUSCLE FATIGABILITY (HISTOCHEMISTRY).

      Stuart, Douglas G.; Rankin, Lucinda Lee; Angevine, Jay B., Jr.; Allen, Ronald E.; Burt, Janis M.; Enoka, Roger M.; Hasan, Ziaul (The University of Arizona., 1987)
      To study the detrimental effects of hypokinesia, many models of reduced muscular activity (i.e., reduced-use), including alterations in the size of the living environment, have been developed. Although significant structural and functional changes have been documented, the effect of reduced-use on muscle fatigability remains unclear. This project was designed to study the effects of cage-size on selected properties of rat hindlimb muscle, with particular emphasis on fatigue. Further, in view of the lack of information on the potential effect of gender, both males and females were studied. The rats were raised in either a small, conventional cage or one approximately 133 times larger. Subsequently, terminal experiments were performed to characterize the contractile properties, fiber-type composition and oxidative potential of two hindlimb muscles of the small- and large-cage-reared rats. The test muscles, soleus and extensor digitorum longus, were selected on the basis of their pronounced differences in function, usage and fiber-type composition. The results suggest that reductions in cage-size can influence the properties of skeletal muscle (specifically, muscle mass, force and fatigability) and that this effect is a function of both gender and interanimal differences. However, due to the large variability exhibited by all three factors, their overall effect will be minimal. An analysis of the response of the test muscles to a 6 min fatigue test revealed three findings. First, both muscles exhibited a wide range of fatigability, an unexpected finding particularly for soleus but in keeping with the multiplicity of factors discussed above. Second, the association observed between whole-muscle force and the electromyogram (e.m.g.) was found to be dependent upon the measure used to quantify the e.m.g., the fiber-type composition of the muscle and its degree of fatigability. And third, a coexistence of twitch potentiation and muscle fatigue was observed which also was dependent upon the fiber-type composition and the extent of fatigue. Finally, a comparison of qualitative and quantitative histochemical analyses revealed broad, overlapping ranges for oxidative enzyme activity for each of the three muscle-fiber types. This suggests that differences in fatigability usually attributed to different fiber types are not due solely to differences in oxidative potential.
    • Caja Costarieccence de Seguro Social: A Case Study in Positive Deviance

      de Zapien, Jill; Anako, Chiamaka (The University of Arizona., 2013)
      In this article, the health care system in the country of Costa Rica is critically analyzed. This analysis is performed in an effort to learn about the historical occurrences that led to the development of Costa Rica's' universal healthcare system. The current system, Caja Costarricense de Seguro Social, is analytically examined. Through this inspection, the problems that are currently being experienced by the country are noted and the missteps of the current leadership, and therefore the program itself, are exposed. Some ways to possibly remedy the challenges of the system are suggested, and practical changes are recommended. Interventions currently in play, as well as those that have been recently implemented are explained as well. Costa Rica's impact on the world stage is noted, and the lessons that the county has learned are suggested as a possible guide to other countries around the globe, whose healthcare systems may also be in flux.
    • Calcium Homeostasis Modulator (CALHM1/2) in Pulmonary Arterial Hypertension

      Yuan, Jason X.-J.; Garcia, Joe G.N.; Rodriguez, Marisela; Vanderpool, Rebecca; Carew, Jennifer S. (The University of Arizona., 2020)
      Calcium Homeostasis Modulator in Pulmonary Arterial Hypertension byMarisela Rodriguez Master of Science (M.S.) in Clinical Translational Sciences University of Arizona, Tucson 2020 Professor Jason Yuan, Co-Chair Professor Joe G.N. Garcia, Co-Chair Pulmonary arterial hypertension (PAH) is a progressive and fatal disease that predominantly affects women. The increased pulmonary arterial pressure (PAP) in patients with PAH is mainly generated by increased pulmonary vascular resistance (PVR) (18, 70, 103). Sustained pulmonary vasoconstriction, excessive pulmonary vascular remodeling, in situ thrombosis, and increased pulmonary vascular wall stiffness are the major causes for the elevated PVR and PAP in patients with PAH. Concentric pulmonary vascular remodeling is among one of the major causes for the elevated pulmonary vascular resistance (PVR) and pulmonary arterial pressure (PAP), also one the major causes for increasing afterload of right ventricle (RV) and inducing right heart failure leading to death if untreated (103). Excessive pulmonary artery smooth muscle cell (PASMC) proliferation and inhibited PASMC apoptosis have been implicated in the development and progression of pulmonary vascular wall thickening in patients with PAH and animals with severe experimental pulmonary hypertension (PH). An increase in cytosolic free Ca2+ concentration ([Ca2+]cyt) in PASMCs is not only a trigger for PASMC contraction and pulmonary vasoconstriction, but also an important stimulus for PASMC proliferation, migration, and pulmonary vascular remodeling (16, 83, 85). [Ca2+]cyt in PASMCs is increased by Ca2+ influx through Ca2+-permeable cation channels in the plasma membrane (PM) and Ca2+ release or mobilization from the intracellular Ca2+ stores, mainly the sarcoplasmic (SR) or endoplasmic (ER) reticulum. There are at least three classes of Ca2+-permeable cation channels identified in human and animal PASMCs that are responsible for Ca2+ influx associated with excitation-concentration coupling (EC-coupling) and Ca2+-mediated PASMC proliferation and migration: (i) voltage-dependent Ca2+ channels (VDCC), (ii) receptor-operated Ca2+ channels (ROCC), and (iii) store-operated Ca2+ channels (SOCC) (50, 57). VDCC are opened or activated by membrane depolarization due to, for example, decreased activity or downregulated K+ channels (57) while ROCC is opened or activated by ligand-mediated binding to membrane receptors including G protein-coupled receptors (GPCR) and tyrosine kinase receptors (TKR). Activation of GPCR or TKR upon binding to respective ligands increases production of diacylglycerol (DAG) and inosital 1,4,5-triphosphate (IP3), two important intracellular second messengers. DAG then activates ROCC and introduces receptor-operated Ca2+ entry (ROCE), while IP3 activates IP3 receptors, also referred to as Ca2+ release channels, in the SR/ER membrane and induces Ca2+ release from the intracellular stores to the cytosol contributing to increasing [Ca2+]cyt. Depletion or significant reduction of Ca2+ levels in the ER/SR due to Ca2+ mobilization or release leads to Ca2+ influx through SOCC, commonly referred to as store-operated Ca2+ entry (SOCE). Active depletion of intracellularly stored Ca2+ in the SR/ER then also results in the dimerization and translocation of STIM1 (and/or STIM2) in the SR/ER membrane and forms STIM protein puncta close to the SR/ER-plasma membrane junctions. Then the multimer STIM1/2 proteins in the ER-PM recruit Orai proteins in the plasma membrane to form SOCC responsible for SOCE (16). It has been shown that transient receptor potential (TRP) channels are involved in forming ROCC in PASMCs and can be activated directly by DAG. In our previous publishing, we have determined that the proliferative phenotype of PASMCs employs SOCC leading to increased expression levels of STIM2, not STIM1, and also Orai2 and TRPC6 expressions from IPAH patients- altogether providing an underlying mechanism for enhanced SOCE. TRP channels are also reported to participate in the regulation of SOCE in many cell types (21). In addition to TRP channels, many other types of Ca2+-permeable cation channels may also participate in ROCE and SOCE. Calcium homeostasis modulators (CALHM) including CALHM1 and CALHM2, have been identified as a family of physiologically important plasma membrane ion channels that are permeable to both cations and anions. These channels are allosterically regulated by membrane voltage (or membrane potential) and extracellular Ca2+; CALHM1 and CALHM2 channels are closed at the resting membrane potential but can be opened by strong membrane depolarization. Reduction of extracellular [Ca2+] increases the probability for CALHM channels to open, which allow the channels to be activated at a negative potential. Ultimately, it is widely known that the increased [Ca2+]cyt due to upregulated and activated Ca2+-permeable cation channels contribute to pulmonary vasoconstriction and excessive proliferation of PASMCs (and other cell types, for example fibroblasts and myofibroblasts) in patients with PAH, eventually this leads to concentric pulmonary vascular remodeling (17). Therefore, a rise in intracellular [Ca2+] and activated Ca2+ in PASMC via upregulated and/or activated Ca2+-permeable cation channels play a major role. CALHM1 and CALHM2 have a significant impact on the pathogenesis that lead to the development and progression of PAH. As discussed earlier, sustained pulmonary vasoconstriction and excessive pulmonary vascular remodeling comprise of two major causes for the elevated PVR and PAP in patients with PAH and animals with experimental PH (50). Pulmonary vasoconstriction is certainly a major cause for increasing PVR and PAP at the early stage of disease development, while concentric pulmonary vascular remodeling and obliterative intima and plexiform lesions are made up of the late state pathological changes that contribute to maintaining high PVR and PAP (57). The transition from the contractile or differentiated phenotype to the synthetic or proliferative phenotype of PASMC is thus an important pathogenic process that promotes vascular remodeling (62) in which we aimed at investigating. In this study, I hypothesized that CALHM1 and/or CALHM2 are involved in PASMC phenotypical transition from the contractile or differentiated phenotype to the synthetic or proliferative phenotype, while CALHM1/2 are upregulated in PASMC from patients with PAH and animals with experimental PH.