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Biomedical subjects

R Yu

Publications and source records attributed to R Yu.

At least 109 records · Page 6Linked to original sources

Modulation of select immune responses by dietary capsaicin.

Capsaicin (CAP) is the spicy principle of hot peppers that has been used as a food additive, preservative, and medicine. In this study, we investigated the effect of dietary CAP on immune status and selected immune responses. BALB/c mice were divided into 5 groups and fed diets with either 0, 5, 20, 50 or 100 ppm CAP for 3 weeks. The parameters measured with lymphocytes included mitogen-induced proliferation, plaque-forming cell number, and total serum immunoglobulin levels. In spleen cells of mice fed 20 ppm CAP there was a greater T-cell mitogen induced, lymphocyte proliferative response. In addition, the number of antibody-producing B cells and serum IgG and IgM levels increased in mice fed 20 ppm CAP as compared to the control with no CAP. The effect of dietary CAP on macrophage activity was assessed by phagocytosis and tumor necrosis factor-alpha (TNF alpha) production. Dietary CAP had no effect on phagocytic activity by peritoneal macrophages, but the levels of secreted TNF alpha increased in the groups fed 20 ppm CAP compared to the control. These results suggest that dietary CAP may differentially enhance immune status as well as select immune functions. That is in contrast with previous studies that show immunosuppression observed after CAP injection.

Animals↗

Expression of heterogeneous nuclear ribonucleoprotein A2/B1 in bronchial epithelium of chronic smokers.

The monoclonal antibody 703D4, which binds heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1), has been reported to detect lung cancer more than a year earlier than routine chest X-ray or cytomorphology. To explore the biological basis of this detection, we studied the expression of this antigen in the central airways of smokers with evidence of bronchial metaplasia using specimens from a previously reported, randomized retinoid chemoprevention trial. By analyzing 1078 available biopsy specimens from 147 individuals at baseline and 68 individuals who completed the intervention, we frequently detected overexpression of hnRNP A2/B1 in normal and abnormal bronchial epithelium (i.e., in 41% of normal and 37% of squamous metaplasia samples). There was no correlation between hnRNP A2/B1 overexpression and the different histological changes. In cases with hnRNP A2/B1 overexpression, immunoreactivity was homogeneously expressed in all biopsied sites. For the 68 cases with serial biopsies, there was no significant modulation of hnRNP expression by retinoid intervention or smoking status. With lung cancer cell lines, 0.5-4 microM concentrations of 13-cis-retinoic acid reduced hnRNP A2/B1 overexpression by immunocytochemistry. We conclude that hnRNP A2/B1 overexpression is frequently found in central airways of chronic smokers, consistent with the pattern of expression that we reported previously in airways surrounding resected primary lung cancers. Oral 13-cis-retinoic acid at a dose of 1 mg/kg has no demonstrable effects on modulating hnRNP A2/B1 expression in proximal bronchial epithelium.

Biomarkers, Tumor↗

Characterization of the polymorphonuclear leukocyte-induced vasoconstriction in isolated human umbilical veins.

We investigated the contractile effects of both activated and unactivated polymorphonuclear leukocytes (PMNs) on human vascular tissue to characterize the influence of human PMNs on vascular tone. PMNs were added either unactivated or after f-met-leu-phe (fMLP) activation (10(-8) M), into tissue chambers containing human umbilical vein segments under either control or cytokine-treated conditions. The activation state of different PMN preparations was measured by immunofluorescence staining of the adhesion glycoproteins Mac-1 and L-selectin. Both unactivated and activated PMNs induced a cell number-dependent (1.5 x 10(5) to 2 x 10(6) cells/ml) vasoconstriction in human umbilical vein segments. This PMN-induced response was not inhibited by treatment with indomethacin (10(-5) M), superoxide dismutase (2 x 10(-7) M) or L-nitro-monomethyl arginine (10(-4) M). However, treatment of PMNs with the leukotriene biosynthesis inhibitor BIRM-270 partially inhibited (-61 +/- 19%, P <.05) the contraction induced only by unactivated PMNs. Moreover, the supernatant from unactivated, but not that from activated, PMNs elicited a contractile response comparable to that from the addition of cells. We observed a significant correlation between the Mac-1/L-selectin ratio of activated PMNs and the contractile response they generated (r = 0.77, P <.05). The activated PMN response had an endothelium-dependent component, whereas the unactivated PMN response was endothelium-independent. These results suggest that human PMNs of varying activation states have the capacity to modulate vascular smooth muscle tone via distinct mechanisms. Unactivated PMNs appear to modulate tone via a secreted product, whereas the more activated phenotype modulates vascular tone via a cognate interaction with the endothelium.

Flow Cytometry↗

Capsaicin can alter the expression of tumor forming-related genes which might be followed by induction of apoptosis of a Korean stomach cancer cell line, SNU-1.

Capsaicin (CAP) has been known to inhibit some tumor development in vivo (J.J. Jang, S.H. Kim, T.K. Yun, Inhibitory effect of capsaicin on mouse lung tumor development, in vivo, J. Korean Med. Sci. 3 (1989) 49-53; J.J. Jang, K.J. Cho, Y.S. Lee, J.H. Bae, Different modifying responses of capsaicin in a wide-spectrum initiation model of F344 rat, J. Korean Med. 6 (1991) 31-36) [1,2] even though its mechanism of action is not well understood. The objectives of this study were to examine the effect of CAP on expression of tumor forming-related genes in a Korean stomach tumor cell, SNU-1. We used slot blot hybridization to investigate its effect on a wide spectrum of proto-oncogenes. It was found that CAP enhanced the transcripts of two proto-oncogenes (c-myc and c-Ha-ras) and tumor suppressor gene p53. While a low concentration of CAP (0.01 microM) did not significantly increase the level of p53 transcript in SNU-1, it did increase it by a factor of 3.5 at a 10 microM dose of CAP. Consequently, SNU-1 cells are sensitive to CAP in the overexpression of tumor suppressor gene, p53 and proto-oncogenes, c-myc and c-Ha-ras, but not those of c-erbB-2, c-jun and bcl-2 genes. Both cell death and DNA fragmentation were shown in SNU-1 cells with treatment of CAP. Our results suggest that CAP induces apoptotic cell death in human gastric cancer cells (SNU-1) in vitro which may be possibly mediated by the overexpression of p53 and/or c-myc genes. Because cell suicide is arguably the most potent natural defense against cancer, the correlation between the induction of apoptosis and the change of tumor forming-related gene expression after CAP treatment should be further studied in detail.

Apoptosis↗

Butylated hydroxyanisole and its metabolite tert-butylhydroquinone differentially regulate mitogen-activated protein kinases. The role of oxidative stress in the activation of mitogen-activated protein kinases by phenolic antioxidants.

Phenolic antioxidant butylated hydroxyanisole (BHA) is a commonly used food preservative with broad biological activities, including protection against acute toxicity of chemicals, modulation of macromolecule synthesis and immune response, induction of phase II detoxifying enzymes, and especially its potential tumor-promoting activities. Understanding the molecular basis underlying these diverse biological actions of BHA is thus of great importance. Here we demonstrate that BHA is capable of activating distinct mitogen-activated protein kinases (MAPKs), extracellular signal-regulated protein kinase 2 (ERK2), and c-Jun N-terminal kinase 1 (JNK1). Activation of ERK2 by BHA was rapid and transient, whereas the JNK1 activation was relatively delayed and persistent. A major metabolite of BHA, tert-butylhydroquinone (tBHQ), also activated ERK2 but weakly stimulated JNK1 activity. Furthermore, tBHQ activation of ERK2 was late and prolonged, showing a kinetics different from that induced by BHA. ERK2 activation by both compounds required the involvement of an upstream signaling kinase MAPK/ERK kinase (MEK), as evidenced by the inhibitory effect of a MEK inhibitor, PD98059. Pretreatment with N-acetyl-L-cysteine, glutathione, or vitamin E attenuated ERK2 but not JNK1 activation by BHA and tBHQ. Modulation of intracellular H2O2 levels by direct addition of catalase or pretreatment with a catalase inhibitor, aminotriazole, also affected BHA- and tBHQ-stimulated ERK2 activity but not JNK1, indicating the involvement of oxidative stress in the ERK2 activation by these two compounds. However, we did not observe any generation of H2O2 after exposure of cells to BHA or tBHQ using a H2O2-sensitive fluorescent probe, 2',7'-dichlorofluorescein diacetate. Instead, BHA and tBHQ substantially reduced the amount of intracellular H2O2. Furthermore, BHA and tBHQ activation of ERK2 was strongly inhibited by ascorbic acid and a peroxidase inhibitor, sodium azide, suggesting the potential role of phenoxyl radicals and/or their derivatives. Taken together, our results indicate that (i) BHA and its metabolite tBHQ differentially regulate MAPK pathways, and (ii) oxidative stress due to the generation of reactive intermediates, possibly phenoxyl radicals but not H2O2, is responsible for the ERK2 activation by BHA and tBHQ, whereas the JNK1 activation may require a distinct yet unknown mechanism.

Amitrole↗

Desensitization of thyrotropin-releasing hormone receptor-mediated responses involves multiple steps.

Desensitization and recovery of the inositol 1,4,5-trisphosphate (IP3) and intracellular free calcium concentration ([Ca2+]i) responses to thyrotropin-releasing hormone (TRH) were measured in HEK293 cells stably expressing the G protein-coupled TRH receptor. TRH caused a large, rapid, and transient increase in IP3 and a biphasic increase in [Ca2+]i. Desensitization of the TRH response was measured by exposing cells to TRH, washing, and then incubating the cells in hormone-free medium before reintroducing TRH and measuring IP3, [Ca2+]i, and intracellular Ca2+ pool size. When cells were incubated with 1 microM TRH for 10 s or 10 min and reexposed to TRH, there was almost no IP3 or [Ca2+]i increase. The IP3 response recovered first, followed by the [Ca2+]i response. The ionomycin-releasable intracellular Ca2+ pool was almost completely depleted by TRH, and pool refilling was slow. Thrombin, endothelin, and carbachol, when combined, stimulated large increases in IP3 and [Ca2+]i, but did not block the IP3 or [Ca2+]i responses to TRH measured 10 min later. In contrast, cells exposed to TRH first responded to combined agonists with a nearly normal increase in IP3, but no rise in [Ca2+]i. Thus, the IP3 response to TRH displays homologous desensitization, whereas the [Ca2+]i response displays heterologous desensitization because depletion of intracellular Ca2+ pools prevents responses to other hormones.

Calcium↗

Clonal genetic alterations in the lungs of current and former smokers.

BACKGROUND AND PURPOSE: Genetic damage has been identified at multiple chromosomal sites (i.e., loci) in lung cancer cells. We questioned whether similar damage could be detected in the bronchial epithelial cells of chronic smokers who do not have this disease. METHODS: Biopsy specimens from six different bronchial regions were obtained from 54 chronic smokers (40 current smokers and 14 former smokers). The presence of squamous metaplasia and dysplasia (abnormal histologic changes) in the specimens was documented by examination of hematoxylin-eosin-stained sections, and a metaplasia index ([number of biopsy specimens with metaplasia/total number of biopsy specimens] x 100%) was calculated for each subject. Loss of heterozygosity (i.e., loss of DNA sequences from one member of a chromosome pair) involving microsatellite DNA at three specific loci-chromosome 3p14, chromosome 9p21, and chromosome 17p13-was evaluated by means of the polymerase chain reaction. Fisher's exact test and logistic regression analysis were used to assess the data. Reported P values are two-sided. RESULTS: Data on microsatellite DNA status at chromosomes 3p14, 9p21, and 17p13 were available for 54, 50, and 44 subjects, respectively. The numbers of individuals who were actually informative (i.e., able to be evaluated for a loss of heterozygosity) at the three loci were 36 (67%), 37 (74%), and 34 (77%), respectively. DNA losses were detected in 27 (75%), 21 (57%), and six (18%) of the informative subjects at chromosomes 3p14, 9p21, and 17p13, respectively. Fifty-one subjects were informative for at least one of the three loci, and 39 (76%) exhibited a loss of heterozygosity. Forty-two subjects were informative for at least two of the loci, and 13 (31%) exhibited losses at a minimum of two loci. Loss of heterozygosity at chromosome 3p14 was more frequent in current smokers (22 [88%] of 25 informative) than in former smokers (five [45%] of 11 informative) (P = .01) and in subjects with a metaplasia index greater than or equal to 15% (21 [91%] of 23 informative) than in subjects with a metaplasia index of less than 15% (six [46%] of 13 informative) (P = .003). In five informative individuals among nine tested nonsmokers, a loss of heterozygosity was detected in only one subject at chromosome 3p14 (P = .03), and no losses were detected at chromosome 9p21 (P = .05). CONCLUSIONS: Genetic alterations at chromosomal sites containing putative tumor-suppressor genes (i.e., 3p14 and the FHIT gene, 9p21 and the p16 gene [also known as CDKN2], and 17p13 and the p53 gene [also known as TP53]) occur frequently in the histologically normal or minimally altered bronchial epithelium of chronic smokers.

Adult↗

Activation of signal transduction kinases by tamoxifen.

PURPOSE: To study the signal transduction mechanisms of tamoxifen via the activation of MAPKs, JNK and ERK in order to understand its regulation of gene expression. METHODS: The effects of tamoxifen (TAM) on the activation of serine/threonine mitogen-activated protein kinase (MAPK, p42/ERK2) and the stress-activated protein kinases (p46 SAPK or c-Jun N-terminal kinase, JNK1) were evaluated using a human cervical epitheloid carcinoma HeLa cell line. RESULTS: TAM activated both JNK1 and ERK2 activities in a time- and dose-dependent manner in HeLa cells. The activation of JNK1 was enhanced when the cells were pretreated with prooxidant H2O2. CONCLUSIONS: These studies show that TAM activates the signal transduction kinases, JNK1 and ERK2, which may play important roles in the regulation of gene expression by TAM.

Antineoplastic Agents, Hormonal↗

Activation of mitogen-activated protein kinases by green tea polyphenols: potential signaling pathways in the regulation of antioxidant-responsive element-mediated phase II enzyme gene expression.

Green tea polyphenols, major constituents of green tea, are potent chemopreventive agents in a number of experimental models of cancer in animals. The mechanisms of cancer protection by these agents are not clear, but may involve modulation of the enzyme systems responsible for the detoxification of chemical carcinogens. The present studies show that a green tea polyphenol extract (GTP) induces chloramphenicol acetyltransferase (CAT) activity in human heptoma HepG2 cells transfected with a plasmid construct which contains an antioxidant-responsive element (ARE) and a minimal glutathione S-transferase Ya promoter linked to the CAT reporter gene. This indicates that GTP stimulates the transcription of Phase II detoxifying enzymes through the ARE. To explore the upstream signaling pathways leading to gene expression, we studied the involvement of the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase 2 (ERK2) and c-Jun N-terminal kinase 1 (JNK1). Potent activation of ERK2 was seen following treatment of HepG2 cells with different concentrations of GTP. Similar to ERK2, JNK1 was also strongly activated by treatment with GTP, although to a lesser extent and in a different dose-dependent fashion. Kinetic studies revealed that GTP activation of JNK1 was delayed and sustained, whereas ERK2 activation was rapid and transient. Furthermore, GTP treatment also increased mRNA levels of the immediate-early genes c-jun and c-fos, as determined by reverse transcriptase-coupled polymerase chain reaction. Taken together, these studies provide insights into the action of GTP and suggest that the stimulation MAPKs may be the potential signaling pathways utilized by GTP to activate ARE-dependent genes.

Calcium-Calmodulin-Dependent Protein Kinases↗

Ameliorating effect of erythromycin on bleomycin-induced pulmonary fibrosis: role of alveolar macrophage activation and cytokine release.

The objective of this study was to evaluate the effectiveness of erythromycin (EM) on bleomycin-induced pulmonary fibrosis in rats and its possible mechanisms. Seventy-five rats were divided into three groups. Alveolar macrophages (AM) were harvested through bronchalveolar lavage (BAL) and consecutive changes of tumour necrosis factor-alpha (TNF-alpha) and platelet-derived growth factor (PDGF) in AM supernatant and bronchoalveolar lavage fluid (BALF) were assayed with ELISA and bioassay, respectively. The AM-derived TNF-alpha was elevated on day 3, peaked day 7 and then decreased but remained at higher level until day 28. The AM-derived PDGF was increased on day 3, peaked on day 7 then decreased to non-statistically significant higher level. The TNF-alpha in BALF was increased significantly on day 3 then decreased to normal level; the peak preceded that of AM-derived TNF-alpha. The PDGF in BALF was increased on day 3, peaked on day 7, and then decreased to normal, which exhibited a consecutive change similar to that of AM-derived PDGF. The EM significantly suppressed TNF-alpha and PDGF release by AM, markedly decreased TNF-alpha and PDGF levels in BALF. The EM also lessened the collagen deposition, the lung hydroxyproline comprised 75.44%, 72.72% and 56.24% that of bleomycin-treated group on day 7, 14 and 28, respectively. In conclusion, EM can ameliorate bleomycin-induced pulmonary fibrosis possibly through suppression of TNF-alpha and PDGF as well as the inhibition on accumulation of inflammatory cells in the lung.

Animals↗

Characterisation of an outer membrane protein of Moraxella catarrhalis.

To elucidate potential vaccine antigens, Moraxella catarrhalis outer membrane proteins (OMPs) were studied. We have previously shown an OMP to be a target for human IgG and have now further characterised this OMP which appears to have a molecular mass of 84 kDa and to be distinct from the 81-kDa OMP, CopB. Human transferrin was shown to bind the 84-kDa OMP alone. N-terminal sequencing of this OMP and purified M. catarrhalis transferrin binding protein B (TbpB) revealed homology both with each other and with the TbpB of Haemophilus influenzae and Neisseria meningitidis. Adsorption of human anti-serum with purified TbpB from two M. catarrhalis strains abolished or reduced binding of IgG to the 84-kDa OMP from three M. catarrhalis isolates. IgG binding to CopB was unaffected. It is clear that the 84-kDa OMP is distinct from CopB and is a likely homologue of TbpB.

Adult↗

Effect of cell type on the subcellular localization of the thyrotropin-releasing hormone receptor.

The localization of an epitope-tagged receptor for thyrotropin-releasing hormone (TRH) expressed in different cell contexts was studied with immunofluorescence microscopy. In pituitary lactotrophs, which normally express TRH receptors, and in AtT20 pituitary corticotrophs, TRH receptor immunoreactivity was primarily confined to the plasma membrane. In HEK 293 and COS7 cells, TRH receptors were predominantly intracellular. In transiently transfected COS7 cells, the TRH receptor colocalized with endoplasmic reticulum and Golgi markers. The pattern of TRH receptor immunofluorescence was the same over a wide range of receptor expression in transiently transfected COS7 cells, and all cell lines bound similar amounts of 3H- and rhodamine-labeled TRH analogs, suggesting that cell-specific differences in TRH receptor localization were not simply the result of overexpression. In all cell contexts, TRH receptors on the plasma membrane underwent extensive ligand-driven endocytosis. Inhibitors of glycosylation did not alter the subcellular distribution of receptors. In HEK 293 cells expressing the transfected TRH receptor, protein synthesis inhibitors caused translocation of intracellular receptors to the cell surface, as shown by a marked increase in cell surface immunofluorescence and [3H][N3-methyl-His2]TRH binding. These results demonstrate that the subcellular localization of the TRH receptor depends on the cell context in which it is expressed and that intracellular receptors are capable of translocation to the plasma membrane.

Amino Acid Sequence↗

DAX-1 inhibits SF-1-mediated transactivation via a carboxy-terminal domain that is deleted in adrenal hypoplasia congenita.

X-linked adrenal hypoplasia congenita (AHC) with hypogonadotropic hypogonadism was recently shown to be caused by mutations in a gene referred to as DAX-1, which encodes a novel member of the orphan nuclear receptor family. DAX-1 is homologous to other nuclear receptors in its carboxy-terminal region, but it lacks the characteristic zinc finger DNA-binding domain. The tissue distribution of DAX-1 (adrenal cortex, gonads, hypothalamus, and pituitary) is the same as that of another orphan nuclear receptor, steroidogenic factor 1 (SF-1), that is required for development of the adrenal glands and gonads. We examined whether DAX-1 and SF-1 might interact in the regulation of SF-1-responsive target genes. Coexpression of DAX-1 and SF-1 inhibited SF-1-mediated transactivation. DAX-1 was shown to interact directly with SF-1 in in vitro protein binding studies; however, it did not interfere with SF-1 binding to DNA in gel mobility shift assays. Transactivation by GAL4-SF-1 constructs was inhibited by DAX-1, indicating that neither the SF-1 DNA-binding domain nor the SF-1 binding sites are required for inhibition by DAX-1. A series of DAX-1 deletion mutants localized the inhibitory domain to the carboxy-terminal region of the protein. Deletion of this domain also reduced basal transcriptional silencing by GAL4-DAX-1. This inhibitory domain has been deleted in all naturally occurring AHC deletion mutants described to date. In addition, two naturally occurring point mutations in DAX-1 exhibited impaired inhibition of SF-1. We conclude that DAX-1 can inhibit SF-1 transcriptional activity and suggest that the loss of this inhibitory property in DAX-1 may account in part for the phenotype of AHC.

Adrenal Insufficiency↗

[Hemodynamic response to exercise in patients with chronic obstructive pulmonary disease (COPD)].

OBJECTIVE: The present study was undertaken to assess the cardiopulmonary response during the initial period of exercise. METHODS: Eight patients with COPD and 10 normal subjects were investigated during exercise (35W) in room air and oxygen breathing for 15 minutes, respectively. Pulmonary arterial mean pressure (mPAP), cardiac output (CO) and mixed venous oxygen saturation (SvO2) were measured by Swan-Ganz catheter during exercise. RESULTS: Compared with normal controls, mPAP in COPD patients was increased and SvO2 decreased markedly both in room air and oxygen breathing during exercise. And CO increased relative slowly than that of normal controls. Furthermore, in patients with COPD, the time to reach their steady state in mPAP and SvO2 during exercise were delayed compared with normal controls. Moreover, we found that the time to reach their steady state in mPAP and SvO2 were shortened when the patients were given oxygen breathing during exercise. CONCLUSIONS: The results indicate that the measurement of initial changes in mPAP and SvO2 during exercise have important clinical significance for evaluating the cardiopulmonary response in patients with COPD.

Blood Pressure↗

Early intervention improves intellectual development in asphyxiated newborn infants. Intervention of Asphyxiated Newborn Infants Cooperative Research Group.

OBJECTIVE: To evaluate the effect of early intervention on the intellectual development in asphyxiated newborn infants. METHODS: Full term asphyxiated infants (Apgar score < or = 6 at 5 minutes after birth) were randomly assigned to early intervention group (34 cases) and conventional care (30 cases) group. The normal control group consisted of 38 infants. Sex, mother's educational background, environmental condition and physical development were not significantly different in the 3 groups. Zero to two years early intervention program was compiled on basis of the national and foreign material about 1 month ahead of average development of the child. It included motor, cognitive, speech development and social behavior. Parents were instructed to carry out early intervention. RESULTS: At the age of 1.5 years, average score of mental development index (MDI) in early intervention group was 14.6 higher than that in conventional care group (F = 18.86, P < 0.0001). MDI score in early intervention group caught up with that in normal control group (F = 2.17, P > 0.05). Conventional care group was 9.7 lower than normal control group (F = 10.14, P < 0.01). Two of 30 cases (6.7%) in conventional care group was mentally retarded while none was mentally retarded in the early intervention group. CONCLUSIONS: The results showed that the early intervention could promote intellectual development of asphyxiated infants and be of much benefit to the prevention of mental retardation.

Asphyxia Neonatorum↗

[Study of dermatomycosis and survey of pathogens in troops of Hainan area].

Subtropical area is the prevalent area of dermatomycosis with natural conditions suptable for the growth and proliferation of fungi causing suterficial dermatomycosis. Dermatomycosis not only brings about certain sufferings to the military personnel in peacetime, but also causes nonbattle loss in manpower in war time. In the present work, a survey of dermatomycosis in Hainan subtropical area of China and isolation of the pathogens were carried out. The results were as follows: The morbidity of superficial dermatomycosis was 34.1% and it was manifested clinically as tinea pedis, tinea versicolor, tinea corporis, tinea axillaris, tinea cruris, etc.; The main pathogen causing dermatomycosis in this area was Trichophyton rubrum which accounted for 50.4% of the pathogens isolated and the next was Trichophyton gypseum which accounted for 20.3%; Trichophyton rubrum could cause dermatomycosis of many sites of the body in this area, but the main lesious were tinea corporis and tinea cruris.

Adult↗