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Biomedical subjects

O L Ramos

Publications and source records attributed to O L Ramos.

At least 37 records · Page 2Linked to original sources

Glomerular hemodynamics and hormonal evaluation during starvation in rats.

The effects of total food deprivation on renal function were evaluated in normal Munich-Wistar rats submitted to starvation (S) periods of two to eight days (Groups S2 to S8). A prompt and sustained decrease in renal plasma flow (RPF) and an increase in total renal vascular resistance (TRVR) were observed after the second day, together with a gradual decrease in glomerular filtration rate (GFR) until the fourth day (40% in the S4 group, P less than 0.05). After this period, a spontaneous and progressive increase in GFR occurred in spite of continuing low RPF and high TRVR. Glomerular hemodynamics were evaluated in additional animals from groups S4 and S7. As observed for whole kidney GFR, mean single nephron (SN) GFR was reduced in group S4, but not in group S7. The decline in SNGFR in S4 was the result of a decline (approximately 40%) in glomerular plasma flow rate (QA) and glomerular capillary hydraulic pressure (PGC), due to a predominant increase (approximately 60%) in afferent arteriolar resistance. In S7, SNGFR and its determinants did not differ from the control. Angiotensin II (Ang II), prostaglandin (but not thromboxane A2, TxA2) inhibition blunted the alterations in whole kidney function observed in S4. Conversely in S7, the inhibition of vasoconstrictor agents (Ang II and TxA2) did not normalize GFR, suggesting that the intrarenal vasoconstriction could be an important factor to maintain GFR after a prolonged period of starvation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Rapid eye movement sleep deprivation and hypertension. Genetic influence.

We studied the importance of genetic predisposition in the development of stress-induced hypertension in the spontaneously hypertensive rat (SHR), Wistar-Kyoto (WKY) rat, and borderline hypertensive rat (BHR; first-generation offspring of SHR and WKY). Rats were submitted to seven 72-hour sessions of rapid eye movement sleep deprivation (REM-sd) every other week during 13 weeks. Tail arterial pressure was determined throughout the experiment. At the end of the study, mean arterial pressure (direct measurement), sympathetic activity (acute blockade with propranolol and phentolamine), and ventricular weight were determined. Results showed that REM-sd induced sustained hypertension only in rats with a partial predisposition to developing hypertension (BHRs). Values of tail arterial pressure at the end of the study were BHR REM-sd, 175 +/- 1.6 mm Hg and control BHR, 155.9 +/- 0.9 mm Hg, p less than 0.05; SHR REM-sd, 219 +/- 2.6 mm Hg and control SHR, 211.9 +/- 3.4 mm Hg, NS; WKY REM-sd, 123.9 +/- 2 mm Hg and control WKY, 125.4 +/- 2.2 mm Hg, NS. Stressed groups showed higher reduction of mean arterial pressure than their controls when submitted to sympathetic blockade (SHR REM-sd, -75.7 +/- 13.2 mm Hg and control SHR, -60 +/- 4.5 mm Hg, p less than 0.05; BHR REM-sd, -38.4 +/- 3.6 mm Hg and control BHR, -24.3 +/- 2.1 mm Hg, NS; WKY REM-sd, -34.4 +/- 2.5 mm Hg and control WKY, -25.6 +/- 3.3 mm Hg, NS). REM-sd increased ventricular weight in all strains. These increments showed no correlation with blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗

Severe hypertension induces disturbances of renal autoregulation.

To study if the severity of hypertension could be associated with disturbances of the autoregulation of renal blood flow and glomerular filtration, we compared the renal hemodynamic and functional responses to acute blood pressure reductions of a group of patients with moderate essential hypertension (n = 10) with those of a group of patients with severe hypertension (n = 10). Blood pressure was reduced to normal levels by a stepwise infusion of sodium nitroprusside, and effective renal blood flow (by 131I-hippuran), glomerular filtration rate (by endogenous creatinine clearance), and filtration fraction were determined. After acute blood pressure normalization, effective renal blood flow and glomerular filtration rate were significantly reduced in patients with severe hypertension (-41.6 +/- 8.3% and -44.7 +/- 6.8%, respectively; p less than 0.01 for both) but not in those with moderate hypertension (+4.9 +/- 9.1% and +6.2 +/- 13.3%, respectively; NS). Filtration fraction remained unchanged in both groups. These results show that severe but not moderate essential hypertensive patients have a displacement to the right of the lower limit of the renal autoregulation curve due to impaired vasodilation to maintain adequate renal blood flow during acute reductions of blood pressure. This impairment may be due to anatomic or functional defects of preglomerular vessels, or to both. Furthermore, the inability to maintain adequate glomerular filtration in these circumstances shows that patients with severe hypertension also have an impaired ability to adjust postglomerular vasomotor tone in the face of reductions in glomerular blood flow.

Adolescent↗

[Treatment of hypertensive crisis in outpatients with sublingual isradipine].

PURPOSE: Evaluate the efficacy and tolerability of isradipine, a new dihydropyridine calcium antagonist in the therapy of outpatients hypertensive crisis. PATIENTS AND METHODS: Twenty seven patients with mean age of 37.2 +/- 2.5 years (ages ranging from 18 to 59 years old) of different races (14 white, 13 not white); 15 men and 12 women, with diastolic blood pressure over 130 mmHg and without signs of recent target organ damage were studied. The patients were divided in three groups according to the used dosage of Isradipine tablets by sublingual route. Group I (n = 10): 1.25 mg; Group II (n = 10): 2.5 mg and Group III (n = 7): 5.0 mg. Arterial blood pressure levels and heart rate were determined before the drug administration and every 30 minutes until 120 minutes after dosing. RESULTS: Mean arterial blood pressure (MABP) decrease significantly in all patients from 153.43 +/- 4.3 to 124.0 +/- 2.3 mmHg after 60 minutes and to 118.0 +/- 2.1 mmHg after 120 minutes (p < 0.001). Heart rate did not show significant changes with the drug. Clinical significant side effects were not observed. The comparative analysis of MABP curves did not show significant differences among the groups I, II and III. However, a tendency of a greater decrease in MABP was observed in the patients of group III. CONCLUSION: Isradipine tablets in the dosages of 1.25, 2.5 and 5.0 mg by sublingual route is effective and well tolerated in the treatment of ambulatorial patients with hypertensive crisis.

Administration, Sublingual↗

Isradipine in the treatment of hypertensive crisis in ambulatory patients.

In order to investigate the efficacy of isradipine in the treatment of hypertensive crisis, we treated three groups of patients who had diastolic blood pressure (DBP) greater than 120 mm Hg, and who were without signs of acute target-organ damage. Isradipine was given sublingually in doses of 1.25 mg (group 1; n = 10), 2.5 mg (group 2; n = 10), and 5 mg (group 3; n = 7). Mean arterial pressure (MAP) was reduced in all patients [from 153.4 +/- 4.3 to 124.0 +/- 2.3 mm Hg at 60 min, and to 118.0 +/- 2.1 mm Hg at 2 h after administration (p less than 0.001)]. The heart rate (HR) did not change significantly (from 82.4 +/- 3.7 to 84.0 +/- 6 beats/min; NS). No significant differences were noted in the overall responses of the three groups; however, blood pressure reduction was more rapid in the group receiving 5 mg compared with the other two dosages. These results show that isradipine given sublingually is effective in reducing the elevated blood pressure of a hypertensive crisis and is not accompanied by limiting side effects. Isradipine's onset of action is early (approximately 30 min after dosing) and reaches its maximum blood pressure response within 2 h of administration. No dose-dependent reductions in blood pressure were observed with the dosage range employed in this study.

Administration, Sublingual↗

Regression of left ventricular hypertrophy in the short-term treatment of hypertension with isradipine.

This was a study of the effectiveness of isradipine, a calcium antagonist of the dihydropyridine group, in reversing left ventricular hypertrophy (LVH) in patients with mild-to-moderate hypertension. Mean arterial pressure was effectively reduced at 90 days of treatment (from 129.5 +/- 2.0 to 111.5 +/- 2.8 mm Hg; P less than .001). The electrocardiographic Romhilt-Estes score for LVH showed early reduction at 45 days of treatment (from 7.1 +/- 0.6 to 5.1 +/- 0.4 points; P less than .001), and further diminutions were observed at 90 days of treatment (3.8 +/- 0.4 points; P less than .01). The echocardiographically determined left ventricular mass indices confirmed these findings (from 175.0 +/- 8.9 to 141.7 +/- 5.5 and to 124.8 +/- 4.2 g/m2; P less than .001) for 45 and 90 days, respectively. The results indicate that isradipine is effective in reducing left ventricular mass and that these reductions are observed early in the course of treatment.

Blood Pressure↗

Metabolic factors for urolithiasis in acromegalic patients.

1. Acromegaly is associated with metabolic disturbances of calcium and phosphorus which can also contribute to renal lithogenesis. 2. In order to characterize these disturbances more precisely, an oral calcium load test was performed on 14 active acromegalic patients. Serum and urinary levels of calcium, phosphorus, uric acid, creatinine and urinary cyclic AMP were determined. 3. Of the 14 patients, 5 (36%) presented hypercalciuria, 5 (36%) presented intestinal calcium hyperabsorption, and 6 (43%) had uric acid hyperexcretion. Two patients (14%) presented nephrolithiasis. 4. The medical records of 32 additional acromegalic patients with or without active disease were reviewed for a history of previous stones, which was observed in three cases (9.5%). 5. The present data suggest that nephrolithiasis occurs more frequently among acromegalic patients because of the underlying metabolic disturbances of calcium presented by this population.

Acromegaly↗

Reversal of left ventricular hypertrophy following treatment of hypertension with isradipine.

In order to complement earlier short-term observations, we studied the effects of isradipine (1.25 or 2.5 mg twice daily) on blood pressure as well as its action in reversing cardiac hypertrophy in 25 moderately hypertensive patients. We observed that the treatment produced short-term (3 month) and longer-term (9 month) control of blood pressure [decreases in mean arterial pressure (MAP) from 128 +/- 2.3 to 112 +/- 2.7 mm Hg and to 105.5 +/- 2.9 mm Hg; p less than 0.001] while heart rate remained constant throughout the study (from 76.6 +/- 2.3 to 74.7 +/- 2.4 beats/min; NS). Reversal of left ventricular hypertrophy (LVH) obtained after 3 months of treatment (LV mass index from 173.7 +/- 8.8 to 135.7 +/- 4.5 g/m2; p less than 0.001) was accentuated with continued therapy (to 131.0 +/- 4.0 and 124.4 +/- 3.1 g/m2 at 6 and 9 months, respectively; p less than 0.01). These results indicate that significant regression of LVH can be obtained with short-term treatment of hypertension with isradipine and that this effect will be fully obtained with longer-term (9 month) therapy.

Adult↗

Survival analysis of 1563 renal transplants in Brazil: report of the Brazilian Registry of Renal Transplantation.

Little is known about renal transplantation activity in developing countries. The objective of this study was to evaluate patient and graft survival among the different types of renal transplant recipients in Brazil. The study population consisted of 1563 patients receiving renal grafts for the first time between 1 October 1987 and 31 December 1989 in 49 transplant centres in Brazil. Data were prospectively collected through individual patient questionnaires. Of the 1563 transplantations performed, 1051 (67%) were from living donors, 467 (30%) from cadaver donors, and 45 (3%) unspecified. A total of 963 (62%) transplants came from living related donors (10% HLA-identical, 45% HLA-haploidentical and 6% HLA-distinct). Among the transplant recipients, only 7% were more than 55 years old, 5% were younger than 15 and 4% had diabetes mellitus. Blacks accounted for 24% of patients receiving transplants. An immunosuppressive regimen, including cyclosporin was used in 75% of cadaver kidney recipients, in 42% of living donor kidney recipients; and in 43% and 75% of HLA-haploidentical and HLA-distinct living related donor recipients, respectively. At 2 years, patient survival for living donor and cadaver donor transplant recipients was 89% and 80% respectively, and graft survival was 76% and 61% respectively. Patient survival for recipients of HLA-identical, haploidentical, and distinct living related donor kidneys was respectively 94%, 90%, and 81% at 2 years, and graft survival was 90%, 75%, and 65% respectively. Graft survival for recipients of HLA-distinct living related donor and non-related donor kidneys compared to cadaver donor kidneys was not significantly different at 2 years (63% vs 61%, P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Effects of systemic hypertension, antidiuretic hormone, and prostaglandins on remnant nephrons.

Renal function was evaluated in normal and after 30 days of 5/6 renal mass reduction (CRF) in Munich-Wistar (MW) rats, spontaneously hypertensive rats with superficial glomeruli (EPM), and in Brattleboro rats with congenital diabetes insipidus (DI). Mean arterial pressure was higher in EPM-Control and EPM-CRF rats as compared with MW and DI rats. MW and EPM rats with CRF showed increases of 120% and 196%, respectively, in single nephron glomerular filtration rate as compared with their controls. However, DI rats with CRF did not show any increase in single nephron glomerular filtration rate as compared with the control group. Therefore, the data suggest that the presence of hypertension enhances the adaptive mechanisms on remnant kidney's function. Conversely, in the absence of antidiuretic hormone, adaptive mechanisms of remnant nephrons did not occur. In addition, it was observed that rats with CRF submitted to prostaglandin blockade with indomethacin showed for MW rats a 55% and 20% reduction in ultrafiltration coefficient and in single nephron glomerular filtration rate, respectively. Decreases of 60% and 30% in ultrafiltration coefficient and single nephron glomerular filtration rate, respectively, were observed for EPM rats. In contrast, DI rats did not show any alteration on renal function after indomethacin. It seems, therefore, that prostaglandins play a role in remnant nephron function of MW and EPM rats, but in the absence of antidiuretic hormone, prostaglandins do not affect remnant glomerular hemodynamics.

Animals↗

Immunoassays of secretory IgA and secretory component.

1. A sandwich-type enzyme-linked immunosorbent assay (ELISA) is described for quantitation of secretory IgA (sIgA) in human serum, as well as an ELISA and a radioimmunoassay (RIA) for measurement of secretory component (SC) in human serum. Samples were reduced and alkylated prior to the measurement of SC. 2. Healthy individuals (N = 53) presented low levels of SC (median, 0.9 mg/l). The protein levels were significantly elevated when compared with the controls, in sera of women during the second (N = 31; median, 1.5 mg/l) and third (N = 35; median, 4.2 mg/l) trimesters of pregnancy and in sera of patients with alcoholic cirrhosis (N = 38; median, 2.4 mg/l) and acute viral hepatitis (N = 25; median, 2.4 mg/l). SC levels of women in the first trimester of pregnancy (N = 24; median, 0.5 mg/l) did not differ from the controls. 3. sIgA levels were also significantly elevated when sera of women in the third trimester of pregnancy (N = 41; median, 25.4 mg/l) and sera of patients with alcoholic cirrhosis (N = 32; median, 75.0 mg/l) or acute viral hepatitis (N = 38; median, 28.5 mg/l) were compared with controls (N = 49; median, 9.0 mg/l). Women in the first (N = 25; median, 7.7 mg/l) and second (N = 29; median, 10.2 mg/l) trimester of pregnancy did not present levels statistically different from the controls. 4. The results obtained for SC by RIA and ELISA were positively correlated (rs = 0.88; P less than 0.001). sIgA levels determined by ELISA were also positively correlated with the results of RIA-SC (rs = 0.77; P less than 0.001) or ELISA-SC (rs = 0.79; P less than 0.001). 5. The assays described are specific, relatively simple to perform, and can be useful for the study of the secretory immune system.

Adult↗

Exposure to hydrocarbons and rapidly progressive glomerulonephritis.

1. A case-control study of the relationship between the regular exposure to hydrocarbons and rapidly progressive glomerulonephritis (GN) was carried out in São Paulo, Brazil. Regular exposure was defined as 1 h or more weekly for 3 consecutive months or longer. We studied 17 patients with rapidly progressive renal failure and biopsy-proven crescentic GN and 34 matched hospital controls. 2. We found an increased risk of rapidly progressive GN associated with exposure to organic solvents (relative risk = 5.00; 95% confidence interval = 1.14 to 22.00). The frequency of exposure to solvents was 52.9% among the patients and 17.7% among the control subjects (P less than 0.05). However, no statistically significant increased risk was detected in those patients who had been exposed to fuels (relative risk = 3.25; 95% confidence interval = 0.76 to 13.89); the proportion of exposure to fuels was 47.1% among the patients and 20.6% among the control subjects. 3. Renal histologic findings suggest that immune complex mediated injury as well as a direct glomerular toxic effect may participate in the pathogenesis of rapidly progressive GN associated with hydrocarbon exposure.

Adolescent↗

Urography versus DMSA scan in children with vesicoureteric reflux.

Following the diagnosis of primary vesicoureteric reflux, identified as part of the investigation of urinary tract infection, 299 refluxing kidneys in 202 children (aged 0-14 years) were prospectively evaluated using intravenous urography (IVU) and the DMSA renal scan at least 4 weeks after urine infection. There was 88% concordance between IVU and the DMSA scan, but in 12% there were discrepancies manifested in 37 kidneys from 31 children. Thirty-four kidneys were normal on IVU but showed scars of reflux nephropathy (RN) on the technetium 99m--dimercaptosuccinic acid (DMSA) renal scan; 4 of these (2 infants and 2 pre-school children) had severe generalized changes on scanning. Three kidneys were normal of DMSA scan and, although abnormal on initial IVU, were considered to be normal when this was repeated. During a follow-up period of 5 years an annual DMSA was undertaken in 194 patients and the renal scars remained unchanged in all except 1 child. The IVU was repeated 1-3 years after the initial study in 31 children in which the results of the first imaging did not agree. In 28 patients (34 kidneys) in which the initial IVU was normal but the DMSA abnormal, IVU evidence of scarring emerged in 30 of 34 kidneys, including the 4 patients with severe generalized damage on the DMSA. We conclude that abnormalities detected by the DMSA scan may precede the radiological findings, especially in young children. Even severe RN can be established in kidneys that appear normal on the IVU.

Adolescent↗

Renal function and glomerular hemodynamics in male endotoxemic rats.

The renal effects of a single intravenous dose of two different E. coli lipopolysaccharides (LPS 0111:B4 and LPS 0127:B8), at the same dose of 100 micrograms/kg, were evaluated in euvolemic Munich-Wistar (MW) rats by whole kidney clearance techniques and micropuncture studies. Following LPS infusion, a significant decrease (8%) in mean BP was observed only in the LPS 0127:B8 treated group. Inulin clearance fell 57% (LPS 0111:B4), P less than 0.01, and 38% (LPS 0127:B8), P less than 0.01. Para-aminohippuric (PAH) clearance decreased 31% (P less than 0.01) and total effective renal vascular resistance rose 70% (P less than 0.03) in response to LPS 0111:B4. No significant change in PAH clearance was noted in the LPS 0127:B8 group. Superficial single nephron glomerular filtration rate (SNGFR) was reduced 69% (LPS 0111:B4), P less than 0.03, and 33% (LPS 0127:B8), P less than 0.02. Superficial glomerular plasma flow fell 48% (LPS 0111:B4), P less than 0.03, and 24% (LPS 0127:B8), P less than 0.03. Both lipopolysaccharides were associated with an increase in afferent arteriolar resistance (RA) which accounted for a reduction in the glomerular capillary hydraulic pressure (PGC). There was no change in the proximal tubular pressure in either group and, therefore, the net transcapillary hydraulic pressures were reduced. No measurable change in the ultrafiltration coefficient. Kf, was observed in either group. In a second set of protocols, the effect of prior administration of indomethacin or captopril on LPS 0111:B4 action was investigated. A significant decrease in BP occurred when animals were pretreated with captopril. Both indomethacin and captopril prevented the renal effects of LPS 0111:B4.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗

Pump performance after regression of cardiac hypertrophy following treatment of hypertension with isradipine.

In view of the possibility that cardiac hypertrophy may be reversed by isradipine, we studied the effect of two different doses of isradipine (1.0 and 7.0 mg/kg per day) on relative cardiac weight in the rat. These doses have proved equipotent in lowering the blood pressure of the two-kidney, one clip model of hypertension. Untreated hypertensive rats had significantly greater cardiac weights than the untreated controls (3.16 +/- 0.06 versus 2.31 +/- 0.05 mg/g, P less than 0.001). Hypertrophy was still present in the group treated with isradipine at 1.0 mg/kg per day (3.17 +/- 0.07 versus 2.30 +/- 0.03 mg/g; P less than 0.001) but not with 7.0 mg/kg per day (2.55 +/- 0.17 versus 2.37 +/- 0.11 mg/g; NS). Functional studies revealed that reversal of cardiac hypertrophy did not affect cardiac performance compared with the ventricles with increased mass. These results suggest that reversal of left ventricular hypertrophy with isradipine is dependent on complex mechanisms, possibly unrelated to the unloading of the heart.

Animals↗

Diabetes mellitus and hypertension. State of the art lecture.

In rats with streptozotocin-induced diabetes an increase in arterial blood pressure was observed as early as the first week after the drug was injected. Blood pressure reached maximal values around the fourth week and remained stable for a long period of follow-up. The responsiveness of these rats to the three major vasopressor hormones, angiotensin II, norepinephrine, and vasopressin, was decreased in the early phase of diabetes and returned to normal in the late phase. Acute treatment at the third, sixth, and twelfth weeks with blockers of these vasopressor hormones resulted in a significant fall in blood pressure at the third week with captopril and at the twelfth week with propranolol plus phentolamine. No significant fall was observed when a specific vasopressin inhibitor was administered. Good control of the blood pressure was obtained when these rats were treated chronically with captopril or prazosin, and partial control was achieved when they were fed a low salt diet. An attenuation in arterial blood pressure levels was observed in rats with two-kidney, one clip hypertension when diabetes was induced by streptozotocin. Plasma creatine levels in diabetic rats were significantly higher than those in control rats only in the sixth and twelfth weeks. Electron microscopy revealed some minor glomerular lesions only at the twelfth week.

Angiotensin II↗

Pindolol, not propranolol, reverses cardiac hypertrophy in renal hypertensive rats.

Reversal of cardiac hypertrophy has been obtained by treatment with some antihypertensive drugs but has not been achieved consistently with beta blockers. To investigate whether this difference might be explained by the distinct hemodynamic actions of the drugs, we studied the effects of propranolol and pindolol, beta blockers with distinct modes of action, on cardiac hypertrophy of hypertensive male Wistar rats, two-kidney, one clip (2K1C) Goldblatt model (n = 33) and sham-operated control rats (n = 34). We also assessed the effects of such therapies on the ventricular pumping ability during open-chest, transient aortic occlusion. Four weeks after surgery, propranolol (5 mg/kg/day p.o.) was given to hypertensive (n = 8) and control rats (n = 11); pindolol was also given orally (1 mg/kg/day) to similar groups (n = 7 and n = 5, respectively). Untreated animals served as controls for both groups. Cardiac hypertrophy developed with hypertension in the untreated rats of the propranolol (3.38 +/- 0.18 vs 2.60 +/- 0.08 mg/g; p less than 0.01) and pindolol groups (3.93 +/- 0.21 vs 2.40 +/- 0.03 mg/g; p less than 0.001). Treatment reversed cardiac hypertrophy in the pindolol-treated (3.01 +/- 0.19 vs 3.93 +/- 0.21 mg/g; p less than 0.001, NS) but not in the propranolol-treated rats (3.24 +/- 0.18 vs 3.38 +/- 0.21 mg/g, NS). The maximal pressure that developed during aortic occlusion in the propranolol group was similar to that observed in the pindolol group. These results indicate that cardiac hypertrophy is reversed by pindolol but not by propranolol, and that this reversal does not interfere with left ventricular pumping ability.

Animals↗

Hypertension. A major public health problem in Brazil.

Data collected from various geographical areas show that hypertension is a major public health problem in Brazil. Hypertension is estimated to occur in over 8 million Brazilians and cardiovascular disease-related mortality figures, to which hypertension is a major contributor, increased from 11.8% of the total mortality rate in 1930 to 30.8% in 1980. Costs involved in the treatment of hypertensive patients are very high since hypertension was among the 3 most frequent clinical diagnoses in outpatient visits in 1985. Hypertension is also a major cause of temporary or permanent work incapacitation among Brazilians and data from São Paulo show that hypertension is very common among workers. Finally, demographic tendencies in São Paulo indicate that older age groups have increased in the general population during the past 2 decades. These data, when taken altogether, indicate that hypertension is a major public health problem in Brazil.

Adolescent↗