Gender-dependent effects of aging on the kidney

It is well known that the kidney plays an important role in the development of cardiovascular diseases such as hypertension. The normal aging process leads to changes in kidney morphology, hemodynamics and function, which increase the incidence of cardiovascular events in the elderly population. These disturbances are influenced by several factors, including gender. In general, females are protected by the effects of estrogens on the cardiorenal system. Several studies have demonstrated the beneficial effects of estrogens on renal function in the elderly; however, the relationships between androgens and kidney health during one’s lifetime are not well understood. Sex steroids have many complex actions, and the decline in their levels during aging clearly influences kidney function, decreases the renal reserve and facilitates the development of cardiovascular disorders. Therefore, in this review, we discuss the cellular, biochemical, and molecular mechanisms by which sex hormones may influence renal function during the aging process.

Cardiovascular effects of the intracerebroventricular injection of adrenomedullin: roles of the peripheral vasopressin and central cholinergic systems

Our objective was to investigate in conscious Sprague-Dawley (6-8 weeks, 250-300 g) female rats (N = 7 in each group) the effects of intracerebroventricularly (icv) injected adrenomedullin (ADM) on blood pressure and heart rate (HR), and to determine if ADM and calcitonin gene-related peptide (CGRP) receptors, peripheral V1 receptors or the central cholinergic system play roles in these cardiovascular effects. Blood pressure and HR were observed before and for 30 min following drug injections. The following results were obtained: 1) icv ADM (750 ng/10 µL) caused an increase in both blood pressure and HR (DMAP = 11.8 ± 2.3 mmHg and ΔHR = 39.7 ± 4.8 bpm). 2) Pretreatment with a CGRP receptor antagonist (CGRP8-37) and ADM receptor antagonist (ADM22-52) blocked the effect of central ADM on blood pressure and HR. 3) The nicotinic receptor antagonist mecamylamine (25 µg/10 µL, icv) and the muscarinic receptor antagonist atropine (5 µg/10 µL, icv) prevented the stimulating effect of ADM on blood pressure. The effect of ADM on HR was blocked only by atropine (5 µg/10 µL, icv). 4) The V1 receptor antagonist [β-mercapto-β-β-cyclopentamethylenepropionyl¹, O-me-Tyr²,Arg8]-vasopressin (V2255; 10 µg/kg), that was applied intravenously, prevented the effect of ADM on blood pressure and HR. This is the first study reporting the role of specific ADM and CGRP receptors, especially the role of nicotinic and muscarinic central cholinergic receptors and the role of peripheral V1 receptors in the increasing effects of icv ADM on blood pressure and HR.

Roles of estrogen and progesterone in modulating renal nerve function in the rat kidney

The maintenance of extracellular Na+ and Cl- concentrations in mammals depends, at least in part, on renal function. It has been shown that neural and endocrine mechanisms regulate extracellular fluid volume and transport of electrolytes along nephrons. Studies of sex hormones and renal nerves suggested that sex hormones modulate renal function, although this relationship is not well understood in the kidney. To better understand the role of these hormones on the effects that renal nerves have on Na+ and Cl- reabsorption, we studied the effects of renal denervation and oophorectomy in female rats. Oophorectomized (OVX) rats received 17β-estradiol benzoate (OVE, 2.0 mg·kg-1·day-1, sc) and progesterone (OVP, 1.7 mg·kg-1·day-1,sc). We assessed Na+ and Cl-fractional excretion (FENa+ and FECl-, respectively) and renal and plasma catecholamine release concentrations. FENa+, FECl-, water intake, urinary flow, and renal and plasma catecholamine release levels increased in OVX vs control rats. These effects were reversed by 17β-estradiol benzoate but not by progesterone. Renal denervation did not alter FENa+, FECl-, water intake, or urinary flow values vs controls. However, the renal catecholamine release level was decreased in the OVP (236.6±36.1 ng/g) and denervated rat groups (D: 102.1±15.7; ODE: 108.7±23.2; ODP: 101.1±22.1 ng/g). Furthermore, combining OVX + D (OD: 111.9±25.4) decreased renal catecholamine release levels compared to either treatment alone. OVE normalized and OVP reduced renal catecholamine release levels, and the effects on plasma catecholamine release levels were reversed by ODE and ODP replacement in OD. These data suggest that progesterone may influence catecholamine release levels by renal innervation and that there are complex interactions among renal nerves, estrogen, and progesterone in the modulation of renal function.

Chronotype ontogeny related to gender

Chronotype is an established concept designed to identify distinct phase relationships between the expression of circadian rhythms and external synchronizers in humans. Although it has been widely accepted that chronotype is subjected to ontogenetic modulation, there is no consensus on the interaction between age and gender. This study aimed to determine the relationship between age- and gender-related changes in the morningness-eveningness character in a large sample of people. A total of 14,650 volunteers were asked to complete the Brazilian version of the Horne and Östberg chronotype questionnaire. The data demonstrated that, on average, women were more morning-oriented than men until the age of 30 and there were no significant differences between men and women from 30 to 45 years of age. In contrast to the situation observed until the age of 30, women older than 45 years were more evening-oriented than men. These results suggest that the ontogenetic development of the circadian timekeeping system is more plastic in men, as represented by the larger amplitude of chronotype changes throughout their aging process. The phase delay of adolescence and phase advance of the elderly seem to be phenomena that are more markedly present in men than in women. Thus, our data, for the first time, provide support that sharply opposes the view that there is a single path toward morningness as a function of age, regardless of gender.

Possible roles of COX-1 in learning and memory impairment induced by traumatic brain injury in mice

People who suffer from traumatic brain injury (TBI) often experience cognitive deficits in spatial reference and working memory. The possible roles of cyclooxygenase-1 (COX-1) in learning and memory impairment in mice with TBI are far from well known. Adult mice subjected to TBI were treated with the COX-1 selective inhibitor SC560. Performance in the open field and on the beam walk was then used to assess motor and behavioral function 1, 3, 7, 14, and 21 days following injury. Acquisition of spatial learning and memory retention was assessed using the Morris water maze on day 15 post-TBI. The expressions of COX-1, prostaglandin E2 (PGE2), interleukin (IL)-6, brain-derived neurotrophic factor (BDNF), platelet-derived growth factor BB (PDGF-BB), synapsin-I, and synaptophysin were detected in TBI mice. Administration of SC560 improved performance of beam walk tasks as well as spatial learning and memory after TBI. SC560 also reduced expressions of inflammatory markers IL-6 and PGE2, and reversed the expressions of COX-1, BDNF, PDGF-BB, synapsin-I, and synaptophysin in TBI mice. The present findings demonstrated that COX-1 might play an important role in cognitive deficits after TBI and that selective COX-1 inhibition should be further investigated as a potential therapeutic approach for TBI.

Abundant immunohistochemical expression of dopamine D2 receptor and p53 protein in meningiomas: follow-up, relation to gender, age, tumor grade, and recurrence

Meningiomas are common, usually benign tumors, with a high postoperative recurrence rate. However, the genesis and development of these tumors remain controversial. We aimed to investigate the presence and implications of a mutated p53 protein and dopamine D2 receptor in a representative series of meningiomas and to correlate these findings with age, gender, tumor grade, and recurrence. Tumor tissue samples of 157 patients diagnosed with meningioma (37 males and 120 females, mean age 53.6±14.3 years) who underwent surgical resection between 2003 and 2012 at our institution were immunohistochemically evaluated for the presence of p53 protein and dopamine D2 receptor and were followed-up to analyze tumor recurrence or regrowth. Tumors were classified as grades I (n=141, 89.8%), II (n=13, 8.3%), or grade III (n=3, 1.9%). Dopamine D2 receptor and p53 protein expression were positive in 93.6% and 49.7% of the cases, respectively. Neither of the markers showed significant expression differences among different tumor grades or recurrence or regrowth statuses. Our findings highlight the potential role of p53 protein in meningioma development and/or progression. The high positivity of dopamine D2 receptor observed in this study warrants further investigation of the therapeutic potential of dopamine agonists in the evolution of meningiomas.

Gender, race and socioeconomic influence on diagnosis and treatment of thyroid disorders in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

Thyroid diseases are common, and use of levothyroxine is increasing worldwide. We investigated the influence of gender, race and socioeconomic status on the diagnosis and treatment of thyroid disorders using data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), a multicenter cohort study of civil servants (35-74 years of age) from six Brazilian cities. Diagnosis of thyroid dysfunction was by thyrotropin (TSH), and free thyroxine (FT4) if TSH was altered, and the use of specific medications. Multivariate logistic regression models were constructed using overt hyperthyroidism/hypothyroidism and levothyroxine use as dependent variables and sociodemographic characteristics as independent variables. The frequencies of overt hyper- and hypothyroidism were 0.7 and 7.4%, respectively. Using whites as the reference ethnicity, brown, and black race were protective for overt hypothyroidism (OR=0.76, 95%CI=0.64-0.89, and OR=0.53, 95%CI=0.43-0.67, respectively, and black race was associated with overt hyperthyroidism (OR=1.82, 95%CI=1.06-3.11). Frequency of hypothyroidism treatment was higher in women, browns, highly educated participants and those with high net family incomes. After multivariate adjustment, levothyroxine use was associated with female gender (OR=6.06, 95%CI=3.19-11.49) and high net family income (OR=3.23, 95%CI=1.02-10.23). Frequency of hyperthyroidism treatment was higher in older than in younger individuals. Sociodemographic factors strongly influenced the diagnosis and treatment of thyroid disorders, including the use of levothyroxine.

Roles of novel biomarkers in progression of cutaneous squamous cell carcinoma

Roles of novel biomarkers was studied in progression of cutaneous squamous cell carcinoma (cSCC) as the most common metastatic skin cancer. The incidence of cSCC is increasing worldwide due to lifestyle changes such as recreational exposure to sunlight and the aging of the population. Because of an emerging need for molecular markers for the progression of cSCC, we set our goal to characterize three distinct novel markers overexpressed in cSCC cells. Our results identified overexpression of serpin peptidase inhibitor clade A member 1 (SerpinA1), EphB2 and absent in melanoma 2 (AIM2) in cSCC cell lines compared with normal human epidermal keratinocytes (NHEKs). Immunohistochemical analysis of SerpinA1, EphB2 and AIM2 revealed abundant tumor cell-specific expression of cytoplasmic SerpinA1 and AIM2 and cytoplasmic and membranous EphB2 in cSCC tumors in vivo. The staining intensity of SerpinA1, EphB2 and AIM2 was significantly stronger in cSCC as compared with carcinoma in situ (cSCCIS) and actinic keratosis (AK). Tumor cell-associated SerpinA1 and EphB2 was noted in chemically induced mouse skin SCC, and the staining intensity was stronger in mouse cSCCs than in untreated skin. AIM2 staining intensity was significantly more abundant in cSCC of organ transplant recipients (OTR) than in sporadic cSCC in vivo. EphB2 knockdown resulted in inhibition of migration in cSCC cells. In addition, knockdown of EphB2 and AIM2 was found to inhibit the proliferation and invasion of cSCC cells and to delay the growth and vascularization of cSCC xenografts in vivo. Altogether, these findings identify SerpinA1 as a novel biomarker for cSCC. In addition, characterization of the roles of EphB2 and AIM2 in the progression of cSCC was implicated them as possible therapeutic targets for the treatment of cSCC particularly in unresectable and metastatic tumors.

Roles of keratins in intestinal health and disease

Intermediate filament keratins (K) play a pivotal role in protein targeting and epithelialcytoprotection from stress as evidenced by keratin mutations predisposing to human liver and skin diseases and possibly inflammatory bowel disease (IBD). The K8-null (K8-/-) mice exhibit colonic phenotype similar to IBD and marked spontaneous colitis, epithelial hyperproliferation, decreased apoptosis, mistargeting of proteins leading to defective ion transport and diarrhea. The K8-heterozygote (K8+/-) mouse colon appears normal but displays a defective sodium (Na+) and chloride (Cl-) transport similar to, but milder than K8-/-. Characterization of K8+/- colon revealed ~50% less keratins (K7, K8, K19, K20) compared to K8 wild type (K8+/+). A similar ~50% decrease was seen in K8+/- mRNA levels as compared to K8+/+, while the mRNA levels for the other keratins were unaltered. K8+/- keratins were arranged in a normal colonic crypt expression pattern, except K7 which was expressed at the top of crypts in contrast to K8+/+. The K8+/- colon showed mild hyperplasia but no signs of inflammation and no resistance to apoptosis. Experimental colitis induced by using different concentrations of dextran sulphate sodium (DSS) showed that K8+/- mice are slightly more sensitive to induced colitis and showed a delayed recovery compared to K8+/+. Hence, the K8+/- mouse with less keratins and without inflammation, provided a novel model to study direct molecular mechanisms of keratins in intestinal homeostasis and ion transport. Different candidate ion transporters for a possible role in altered ion transport seen in the K8-/- and K8+/- mouse colon were evaluated. Besides normal levels of CFTR, PAT-1 and NHE-3, DRA mRNA levels were decreased 3-4-fold and DRA protein nearly entirely lost in K8-/- caecum, distal and proximal colon compared to K8+/+. In K8+/- mice, DRA mRNA levels were unaltered while decreased DRA protein level and patchy distribution was detected particularly in the proximal colon and as compared to K8+/+. DRA was similarly decreased when K8 was knocked-down in Caco-2 cells, confirming that K8 levels modulate DRA levels in an inflammation-independent manner. The dramatic loss of DRA in colon and caecum of K8-/- mice was responsible for the chloride transport defect. The milder ion transport in K8+/- colon might be related to DRA suggesting a role for K8 in regulation of DRA expression and targeting. The current study demonstrates the importance of keratins in stress protection and cell signaling. Furthermore, we have also successfully developed a novel, simple, fast, cost effective, non-invasive in vivo imaging method for the early diagnosis of murine colitis with specificity for both genetic and experimental colitis. The said modality provides continuous measurements of reactive oxygen and nitrogen species (RONS) and minimizes the use of an increased number of experimental animals by using a luminal derivative chemiluminescent probe, L-012 which provides a cost-effective tool to study the level and longitudinal progression of colitis.

Gender-toiminta osana sotilaallista kriisinhallintaa : rekrytointi, koulutus ja operatiivinen toiminta

Kansainväliset sotilaalliset kriisinhallintaoperaatiot ovat muuttuneet yhä vaativammiksi, ja kriisinhallinnan tehtäväkenttä on laajentunut ja monipuolistunut. Operaatioalueella olevilta kriisinhallintahenkilöiltä odotetaan yhä enemmän kykyä yhteistyöhön kaikkien toimijoiden kanssa yhteiskunnan vakauden ja turvallisuuden palauttamiseksi ja säilyttämiseksi. Yhdistyneiden kansakuntien päätöslauselman 1325 ”Naiset, rauha ja turvallisuus” täytäntöönpanolla halutaankin hyödyttää koko yhteiskunnan vakautta ja kehitystä. Suomen kansallisen toimintaohjelman ja Pääesikunnan normin mukaan Suomi tukee naisten kouluttautumista kohti vaativimpia tehtäviä ja esittää naisia kansainvälisiin johtotehtäviin. Suomi varmistaa, että kaikilla kriisinhallintatehtäviin lähtevillä on ihmisoikeus- ja tasa-arvokysymysten asiantuntemus sekä kyky tehdä yhteistyötä sisällyttämällä YK:n päätöslauselma 1325, kansainvälinen oikeus, kansainvälinen humanitaarinen oikeus sekä ihmisoikeusvelvoitteet kaikkeen kriisinhallintakoulutukseen. Suomi sisällyttää gender-näkökulman osak-si kriisinhallintajoukkojen operatiivista toimintaa huomioimalla gender-näkökulman operaatioiden suunnittelussa, toimeenpanossa ja raportoinnissa YK:n päätöslauselman 1325 ja operaatiokohtaisten määräysten mukaisesti. Tutkielman tarkoituksena oli tutkia puolustusvoimien virassa olevien naisupseerien motiiveja hakeutua kriisinhallintatehtäviin, naisten osallistumisen vaikutuksia kriisinhallintaoperaatioihin sekä gender-näkökulman huomioimista koulutuksessa ja kriisinhallintajoukon operatiivisessa toiminnassa. Tutkimusongelmana oli vähäinen aiempi tiedon määrä Suomen kansallisessa toimintaohjelmassa ja Pääesikunnassa määritetyn gender-toiminnan toteutumisesta. Päätutkimuskysymyksen avulla pyrittiinkin selvittämään, miten gender-toiminta on toteutu-nut sotilaallisen kriisinhallinnan rekrytoinnissa, koulutuksessa ja operatiivisessa toiminnassa. Tutkimusstrategiana sovellettiin monimenetelmäistä tiedonkeruutapaa määrällisen ja laadullisen aineiston saamiseksi. Tutkimusmenetelminä käytettiin survey-tutkimusta ja sisällönanalyysiä, joiden avulla pyrittiin kuvaamaan naisupseerien, operaatioista kotiutuneiden rauhanturvaajien sekä Afganistanin kriisinhallintaoperaatiossa (ISAF) palvelleiden SKJA:n komentajien ja naisupseerien käsityksiä, mielipiteitä ja asenteita tutkittavasta aiheesta. Tutkielman empiirinen osuus perustuu naisupseereille suunnattuun kyselyyn sekä SKJA:n komentajien ja naisupseerien sähköpostihaastatteluun. Tutkielmassa hyödynnettiin lisäksi Porin prikaatin kotiutuneille rauhanturvaajille teettämän tasa-arvokyselyn tuloksia. Tutkielman tuloksena ilmeni, että naisrauhanturvaajien kriisinhallintatehtäviin osallistumisen vaikutuksista merkittävimpiä olivat yhteyden saaminen paikalliseen naisväestöön. Myös miesten ja naisten työskentely yhdessä samoissa tehtävissä nähtiin tärkeänä esimerkkinä sukupuolten tasa-arvosta. Sukupuolen liiallinen korostaminen nähtiin haitalliseksi, ja tehtävän vaatimukset tuleekin asettaa tehtävässä tarvittavien ominaisuuksien, tietojen ja taitojen mukaisesti. Positiivisten vaikutusten saavuttamiseksi naisten määrän kriisinhallintatehtävissä tulisi kasvaa nykyisestä, mutta sen ei tule olla itseisarvo. Merkittävimmät naisupseerien kriisinhallintatehtäviin hakeutumattomuuden syyt olivat perheen perustamiseen liittyvät sosiaaliset syyt. Kriisinhallintatehtäviin hakeutumisen motivaatiota kasvattavista tekijöistä tärkeimpiä olivat ammattitaidon ja itsensä kehittäminen. Gender-koulutuksen osalta ilmeni, että Suomessa annetaan gender-peruskoulutus mutta operaatioalueella ei täydennyskoulutusta annettu. Gender-näkökulman huomioon ottaminen kriisinhallintajoukon operatiivisessa suunnittelussa, toimeenpanossa ja raportoinnissa ei myöskään tulosten perusteella toteutunut. Tutkielman johtopäätöksenä todetaan, että naisupseerit ovat pääosin halukkaita palvelemaan kriisinhallintatehtävissä, vaikka osallistuminen onkin henkilömäärältään vähäistä. Naisten mahdollisuuteen hakeutua kriisinhallintatehtäviin voidaan vaikuttaa laatimalla urasuunnitelma varhaisemmassa vaiheessa ja lisäämällä naisupseereille kohdennettua tietoa kriisinhallintatehtävistä. Kriisinhallintatehtäviin halukkaita naisia on enemmän kuin näyttäisi olevan mahdollista irrottaa kotimaan tehtävistä. Gender-koulutuksen todettiin olevan liian yleisellä tasolla eikä sitä kyetty konkreettisesti huomioimaan ja soveltamaan joukon operatiivisessa toiminnassa. Koulutuksen pääpainon tulisikin olla operatiivisessa vaikuttavuudessa osana kaikkea koulutusta. Gender-näkökulma tulisi saada integroitua osaksi kaikkea kriisinhallintajoukon toimintaa operaation vaikuttavuuden ja tavoitteiden täyttymisen näkökulmaa. Operaation tavoitteita asetettaessa tulisi muistaa, että kriisinhallintaoperaatioilla pyritään kokonaisvaltaisesti turvallisuusympäristön parantamiseen ja normaaliyhteiskunnan toimintojen ja palvelujen palauttamiseen. Gender-toiminnan kehittämisessä tärkeää onkin ymmärtää sen vaikutus ja kytkeminen nimenomaan paikallisväestön eri ihmisryhmien huomioimiseen ja tasavertaisuuteen ihmisoikeuksien näkökulmasta. Tutkielman tulosten mukaan kehityskohteita gender-toiminnan parantamiseksi on olemassa, ja mikäli kriisinhallintaoperaatioiden vaikuttavuutta halutaan tehostaa, näyttäisi siihen myös olevan keinoja.

The Impact of Foreign Direct Investment Inflows on the Economic Growth of Bangladesh. The Roles of Infrastructural Facilities

Foreign direct investment (FDI) inflow has been a key concern for Bangladesh to obtain additional support for the economic development. The Government of Bangladesh continuously competing with other South Asian countries and putting more effort to increase the number of FDI inflows in the country. From the country’s perspective, the constant increasing rate of economic growth shows a positive outcome of FDI inflow. However, the country still not performing up to the mark to pull enough FDI inflows to its potential. Thus, this study discusses about the major determinants and factors affecting FDI inflows in Bangladesh. Among those determinants and factors, infrastructural facility is considered as the most important to affect FDI inflows. FDI inflow is fundamentally depending upon infrastructural facilities to achieve its desire success. Foreign investors take this issue very seriously because based on this they can measure their ease of doing business in the host country. Despite of providing a large market size, due to having weak and lack of infrastructural facilities, Bangladesh is facing trouble in drawing attention of the foreign investors. In order to make the infrastructural facilities happen, it is highly required to organize each of the systems under of it. The body of this study discussed about the weak infrastructures in Bangladesh such as transport and communication, power and energy, education system, and governance services. Improvement in one of these systems cannot provide valuable positive changes on FDI inflows. It requires improvement in all the weak systems to grasp multinational companies and attract foreign investors. On the basis of this research problem, research questions are established. Both qualitative and quantitative methods are used to answer the research questions. Furthermore, several theories have been applied to justify possible scenarios from the research problem. In addition, the history in between Bangladesh, trade liberalization, and FDI inflows is presented briefly.

The Impact of Foreign Direct Investment Inflows on the Economic Growth of Bangladesh. The Roles of Infrastructural Facilities

Foreign direct investment (FDI) inflow has been a key concern for Bangladesh to obtain additional support for the economic development. The Government of Bangladesh continuously competing with other South Asian countries and putting more effort to increase the number of FDI inflows in the country. From the country’s perspective, the constant increasing rate of economic growth shows a positive outcome of FDI inflow. However, the country still not performing up to the mark to pull enough FDI inflows to its potential. Thus, this study discusses about the major determinants and factors affecting FDI inflows in Bangladesh. Among those determinants and factors, infrastructural facility is considered as the most important to affect FDI inflows. FDI inflow is fundamentally depending upon infrastructural facilities to achieve its desire success. Foreign investors take this issue very seriously because based on this they can measure their ease of doing business in the host country. Despite of providing a large market size, due to having weak and lack of infrastructural facilities, Bangladesh is facing trouble in drawing attention of the foreign investors. In order to make the infrastructural facilities happen, it is highly required to organize each of the systems under of it. The body of this study discussed about the weak infrastructures in Bangladesh such as transport and communication, power and energy, education system, and governance services. Improvement in one of these systems cannot provide valuable positive changes on FDI inflows. It requires improvement in all the weak systems to grasp multinational companies and attract foreign investors. On the basis of this research problem, research questions are established. Both qualitative and quantitative methods are used to answer the research questions. Furthermore, several theories have been applied to justify possible scenarios from the research problem. In addition, the history in between Bangladesh, trade liberalization, and FDI inflows is presented briefly

The roles and tasks of salespeople in Software-as-a-Service company's value-based sales process

Recent research in relationships marketing and sales and sales management emphasizes companies’ ability to create customer value as a core of all business-to-business relationships. The role of individual salespeople in business relation-ships is commonly acknowledged, but has been largely neglected in extant literature. This study offers especially more detailed perspective on salespeople’s roles and tasks in business-to-business value-based sales process. It focuses especially on Software-as-a-Service business environment. The objective of the study is to find out how salespeople can create value in Software-as-a-Service value-based sales process. It determines value-based sales process, salespeople’s roles and tasks in it, and combines value assessment in to process. The results indicate that salespeople have to adapt different selling roles and tasks in Software-as-a-Service value-based sales process to be able to support the customer’s value-in-use experience. The process itself is highly complex, consisting of multiple facets and selling behaviors, and involves relevant actors from both parties of relationship. The study concludes with a discussion of possibilities that provide interesting aspects for future research.