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PubMed2003

Olfaction in essential tremor patients with and without isolated rest tremor.

An olfactory deficit is present in patients with essential tremor (ET), but it is often milder than that in patients with Parkinson's disease (PD). In both, the deficit occurs early in the disease. Isolated rest tremor without other signs of parkinsonism can occur in patients with ET. If the rest tremor in these patients represents a manifestation of ET rather than early PD, we hypothesized that their University of Pennsylvania Smell Identification Test (UPSIT) scores would be similar to those of ET patients without rest tremor. The mean UPSIT score in 13 ET patients with isolated rest tremor did not differ from that of 58 ET patients without rest tremor (29.3 +/- 4.3 vs. 29.4 +/- 6.4; P = 0.69). Several ET patients with rest tremor had UPSIT scores that fell outside of the range that is seen in 95% of patients with PD. These data raise the possibility that some ET patients with isolated rest tremor may not have early PD and that the pathological process that is responsible for their ET is also involving the basal ganglia.

Aged↗
PubMed2000

Entomophthora muscae resting spore formation in vivo in the host Delia radicum.

The formation in vivo of Entomophthora muscae resting spores was investigated in the host, Delia radicum (cabbage root fly), by analysis of field data on the seasonal occurrence of E. muscae resting spores over 4 years. E. muscae resting spores in D. radicum were spherical with an average diameter of 39.4 microm, and the average numbers produced were estimated at 5.7 x 10(4) resting spores/female cadaver. Resting spores were found only after midsummer in D. radicum and almost exclusively in females. The proportion of infected females with resting spores was negatively correlated with average weekly day length after midsummer. We did not detect any significant year effect; thus, the results support the hypothesis that the photoperiod is the most important abiotic factor controlling E. muscae resting spore formation in D. radicum.

Animals↗
PubMed1993

The role of sarcoplasmic reticulum and Na-Ca exchange in the Ca2+ extrusion from the resting myocytes of guinea-pig heart: comparison with rat.

Inhibition of the Na-Ca exchange at the beginning of rest in isolated myocytes of the guinea-pig heart by means of superfusion with Na,Ca-free solution or 5.0 mM Ni2+ resulted in appearance of multiple phasic contractures. Contractures could not be initiated when the sarcoplasmic reticulum (SR) Ca2+ had been depleted by short (1 s) or steady state exposure to 10 mM caffeine, 0.1 microM ryanodine or due to rapid spontaneous release of the SR Ca2+ occurring sometimes at the beginning of rest. Superfusion with 2 x 10(-7) M thapsigargin, which blocked the SR Ca2+ uptake, prevented contractures otherwise initiated by superfusion with the Na,Ca-free solution. The frequency of spontaneous contractures was positively related to the rate of stimulation before rest and negatively related to the duration of rest before superfusion with the Na,Ca-free solution. It is proposed that in guinea-pig myocardium Ca2+ taken up by the SR from sarcoplasm or other cellular compartments like mitochondria, is released during diastole and rest to the subsarcolemmal space from which it is extruded by means of Na-Ca exchange. The release is a primary event not dependent on decrease of the resting sarcoplasmic free [Ca2+] by the outward Ca2+ transport. Inhibition of the Na-Ca exchange at the beginning of rest did not initiate any contractile response in rat myocytes. If the spontaneous contractures were already present, they were inhibited by superfusion with the Na,Ca-free solution. The result reflects the basic difference in the properties of SR of guinea-pig and rat.

Animals↗
PubMed1995

Determination of resting free calcium in barnacle muscle using modified aequorins, buffered calcium injections, and simultaneous image-intensified video microscopy.

Knowing the resting free calcium is important in understanding the role of calcium as an intracellular second messenger. We used a bracketing (null) technique with a luminescent calcium indicator, aequorin, microinjection and image-intensification to measure free calcium in single muscle fibres from the barnacle, Balanus nubilus. We injected modified aequorins (recombinant, and hch-) which after a 30 min diffusion gave reasonable resting glows. Subsequent injection of calcium (strongly buffered with either EGTA or BAPTA, 10 mM) increased or decreased the resting glow depending on the free calcium level in the injected buffer solution. This bracketing (null) method is inherently accurate, but mechanical artifacts on calcium injection reduce the accuracy when total light emission is measured. We therefore used image-intensified video-microscopy of the injected region and video processing (Image-1) of artifact-free regions, to greatly improve the consistency. The luminescence in a pre-selected region of the muscle fibre was measured as a function of time during the injection. Solution calciums were chosen so that if the first injection decreased the resting glow, the second increased it, or vice versa, thus bracketing the true resting value. We used two methods to determine the true value bracketed by our injections: (1) a linear interpolation using the fractional changes in luminescence or (2) a power law interpolation assuming a 2.2 or 2.5 power relationship between luminescence and free calcium. Using these methods, we estimated the free calcium level in the lateral depressor fibres of freshly dredged barnacles to be 279 +/- 36 nM (+/- SD), 339 +/- 42 nM, or 352 +/- 45 nM for the linear, 2.2 and 2.5 powers respectively under the conditions of hch-aequorin and BAPTA buffers (using a K'Ca for BAPTA of 3.0 x 10(6) M-1 for our conditions). Recombinant-aequorin gave essentially the same result while EGTA buffers yielded a somewhat higher value but because of influences of pH on the K'Ca for EGTA (taken as 6.7 x 10(6) M-1 for our conditions) was considered less reliable. Minor changes in [Mg2+] upon buffer injection can lead to underestimates of the true resting [Ca2+] by at most 10%. Thus, we estimate the resting free calcium in barnacle muscle fibres to be 300-380 nM.

Aequorin↗
PubMed1983

Excitation- and rest-dependent shifts of Ca in guinea-pig ventricular myocardium.

The rest- and excitation-dependent shifts of Ca and 45Ca in the isolated, perfused ventricles of guinea-pig hearts were investigated. As much as 50% of the total Ca content (2.2 mmol/kg ww) found in the ventricular muscle stimulated at a steady rate of 60/min, was released into perfusate during 4 min of rest. In the preparations perfused with 45Ca containing solution during the 4 min of rest or during the last 20 s of rest only, a single beat resulted in extra uptake of 0.359 and 0.287 mmol of labelled calcium (45Ca) per kg ww, respectively. Single post-rest excitation evoked in the ventricles which were previously perfused with radioactive solution for 64 min, resulted in increase in tissue 45Ca content by 0.229 mmol/kg ww. In these preparations, the gain in 45Ca is equivalent to the net Ca uptake. Continued post-rest stimulation at the rate of 60/min resulted in recovery of pre-rest content of 45Ca and of total Ca. Gain of 45Ca was paralleled by recovery of contractile force. Uptake of 45Ca in the preparations stimulated at the steady rate of 60/min was 0.137 mmol/kg ww and its value did not depend on the number of beats during exposure to the isotope. Thus 45Ca uptake over a number of steady-state beats may be regarded as equal to the uptake in a single beat. This uptake is by orders of magnitude larger than reported previously by other authors. It is proposed that contraction is triggered by Ca influx into the excited cells (Ca1), and that the response of contractile proteins to this trigger is controlled by a large intracellular Ca2 fraction whose volume is rate-dependent.

Animals↗
PubMed1985

Effect of rest deprivation on motor activity of fish.

The rest-activity behavior of two fish species, Cichlosoma nigrofasciatum and Carassius auratus kept under 12-h light-12-h dim condition was investigated. Rest and activity were determined from continuous time-lapse video recordings. Three states were discriminated based on the degree of motor activity. Both species exhibited a clear rest-activity rhythm with activity predominating during the light period. 'Rest deprivation' was carried out in perch during the habitual dim period by exposing the animals to either 12 h continuous light or to 6 h intermittent light (1 h light - 1 h dim for 12 h). Both light schedules enhanced activity and reduced rest. Light-induced activation was followed by an increase in low activity and rest behavior which prevailed for 12 h following continuous light, and for 6 h following intermittent light. The results indicate that homeostatic mechanisms are involved in the regulation of rest and activity in fish. These mechanisms may be similar to those underlying sleep regulation in mammals.

Activity Cycles↗
PubMed2001

Effect of continuous rectal distention on anal resting pressure.

PURPOSE: Intermittent distention of the rectum induces internal anal sphincter relaxation, but whether continuous rectal distention might affect the resting pressure of the anal canal and the frequency of internal anal sphincter relaxations has not yet been investigated. The aim of this study was to record anal pressure under resting conditions and at two levels of continuous rectal distention. METHODS: Anal pressure was recorded by means of water-perfused catheters under resting conditions and at two levels of rectal distention controlled by an electronic barostat in eight healthy subjects. RESULTS: Continuous rectal distention did not significantly change mean anal resting pressure, but it did significantly decrease the amplitude of ultraslow waves (from 29 +/- 9 mmHg under resting conditions to 23 +/- 6 and 21 +/- 3 mmHg during lesser and greater rectal distention; P = 0.017 and P = 0.012, respectively) and increase the frequency of internal anal sphincter relaxations (from 1.3 +/- 1.3/hour under resting conditions to 8.8 +/- 4.3/hour and 11.0 +/- 4.8/hour during lesser and greater distention; P = 0.012 in both comparisons). CONCLUSIONS: The resting pressure of the anal canal is maintained during continuous rectal distention. The decreased amplitude of ultraslow waves and increased frequency of the internal anal sphincter relaxations induced by rectal distention reveal a complex functional relationship between the rectum and the anal canal.

Adult↗
PubMed1991

Elevation of resting fluid secretion precedes trophic responses in the rat pancreas following a single oral administration of Camostat.

A single dose of the synthetic proteinase inhibitor, Camostat (FOY-305; 100 mg/kg), was administered orally to rats. Pancreata were isolated and then perfused to examine the change in the level of resting fluid secretion. As early as 6 h after administration of the single dose of Camostat, the resting fluid secretion was significantly elevated. Twelve hours after administration, resting fluid secretion was maximally elevated, whereas contents of trypsinogen, chymotrypsinogen, and amylase per DNA in the pancreas were significantly decreased. After 12 h, the level of resting fluid secretion gradually decreased to the control resting level in contrast to significant increases in contents of the pancreatic enzyme and zymogens, and wet weight in acinar cells. We further examined the mechanism mediating the elevated resting fluid secretion. Our results are compatible with the view that the elevation of resting fluid secretion may be maintained by spontaneous activation of ion transporters: an ouabain-sensitive Na-K ATPase, an amiloride-sensitive Na-H antiporter, and a unique Cl transporter that is insensitive to furosemide, bumetanide, SITS, and DNDS.

Administration, Oral↗
PubMed1993

Usefulness of resting thallium-201 delayed imaging for detecting myocardial viability in patients with previous myocardial infarction.

To test the feasibility of resting thallium-201 (201Tl) initial and delayed scintigraphy for detecting the area of viable myocardium, we performed single photon emission computed tomography (SPECT) in 57 patients with previous myocardial infarction (MI). All had received coronary arteriography (CAG) and left ventriculography (LVG). Initial and delayed myocardial imagings were carried out 10 min and 2 hours, respectively, after the injection of 201Tl at rest. Redistribution was judged by visual interpretation and/or the circumferential profile curve, and found in the infarcted or its adjacent area in 40 of the 57 cases (70.2%). A negative washout (net increase of 201Tl uptake in delayed image) was detected in 17 of these 40 cases. In 10 of the 57 patients, both exercise and rest-injected 201Tl myocardial images were obtained at exercise and rest, and compared visually. The areas of abnormal perfusion were smaller in the resting delayed images than those seen after exercise in 9 of the 10 cases, and were equal in one case. Thus, resting 201Tl delayed myocardial scintigraphy appears to reduce the underestimation of the size of the viable myocardium by the usual 201Tl images obtained after exercise or by single initial images obtained at rest in patients with previous MI.

Adult↗
PubMed2001

Early detection of myocardial ischaemia in the emergency department by rest or exercise (99m)Tc tracer myocardial SPET in patients with chest pain and non-diagnostic ECG.

Chest pain (CP) represents a frequent reason for presentation at the emergency department (ED). A large proportion of patients have non-diagnostic ECG on presentation, and in many cases several hours have elapsed since onset of symptoms. Acute rest myocardial scintigraphy (rest SPET) has been shown to have a relevant role in the detection of patients at risk for coronary events, but its sensitivity and negative predictive value are optimal only within the first 3 h following onset of symptoms. In those with delayed presentation, exercise SPET alone, as a screening approach, appears more promising, but its feasibility and diagnostic role in the ED are still unresolved. A total of 231 consecutive patients with a recent-onset (<24 h) first episode of CP had a negative first-line work-up including ECG, troponins, creatine kinase-MB and echocardiography. These patients were considered at low risk for short-term coronary events. Patients were studied with rest SPET if they presented <3 h after onset of CP and exercise SPET if they presented after > or =3 h. The end-points of the study were detection of significant coronary artery disease (CAD) by angiography and major coronary events or cardiac death at 6 months. Eighty patients (35%) underwent rest SPET, while 151 (65%) underwent exercise SPET. Two of the 159 patients with negative SPET had evidence of critical CAD at 6-month follow-up (one patient in the rest SPET group and one in the exercise SPET group; P=NS). Of the 72 patients (31%) with a positive scan, 34 (15%) had documented CAD (16 patients in the rest SPET group and 18 in the exercise SPET group; P=NS). Sensitivity, specificity, accuracy and predictive value were not statistically different between the two groups. In conclusion, the accuracy of exercise SPET in patients with CP and delayed presentation to the ED is comparable to that of validated rest SPET in patients with early presentation. Owing to the high negative predictive value (99%), exercise SPET is especially valuable as a screening tool for the exclusion of CAD in low-risk patients and implementation of early discharge.

Aged↗
PubMed1997

Seasonal variation in the resting metabolic rate of male wood mice Apodemus sylvaticus from two contrasting habitats 15 km apart.

Diurnal and nocturnal resting metabolic rates of winter- and summer-acclimatized adult male wood mice Apodemus sylvaticus from two adjacent populations, 15 km apart, were measured. One population lived in deciduous woodland, and experienced a narrower daily range of temperatures than the second population, which inhabited maritime sand-dunes. Ambient temperature and body mass had significant effects on the resting metabolism of mice, excluding winter-acclimatized sand-dune animals where only temperature explained significant amounts of the observed variation. Only in this latter group could a thermoneutral zone be determined, with a lower critical temperature of ca. 25 degrees C and resting metabolism of 0.155 W. Nocturnal resting metabolic rates were significantly greater than diurnal levels. Winter acclimatization was associated with reductions in thermal conductance and resting metabolism, thus minimizing energy expenditure at rest. Site differences in thermoregulatory strategies were only found in winter, thermal conductances remained similar but mice from the sand-dunes had significantly lower metabolic rates than those from the woodland. Winter acclimatization in wood mice was influenced by factors in addition to photoperiod. Intra-specific and individual variations in resting metabolism, as shown in this study, potentially have a pronounced effect on the daily energy expenditure of a free-living animal.

Acclimatization↗
PubMed1983

Resting and exercise left ventricular function in patients with hypertrophic cardiomyopathy.

Left ventricular ejection fraction (EF) at rest and during exercise was measured in 19 patients with hypertrophic cardiomyopathy (HCM) by means of radionuclide angiography. The results were compared to those in 20 normal subjects. Based on hemodynamic data, patients with HCM were divided into three groups. In group I, no demonstrable left ventricular outflow obstruction, there were five patients; their mean EF increased from 68% +/- 8.9 (+/- SD) at rest to 74% +/- 9.2 during exercise (p less than 0.05). In group II, latent obstruction, there were six patients; their mean EF at rest (75.2% +/- 8.2) and at peak exercise (78.7% +/- 6.7) was not statistically different (p greater than 0.05). Group III, obstruction present at rest, consisted of eight patients; EF at rest (82.6% +/- 8.5) decreased significantly during exercise (75.6% +/- 7.7, p less than 0.01). In normal subjects resting EF was 66.3% +/- 7.6; it increased to 76.4% +/- 7 (p less than 0.001). Exercise duration and heart rate-blood pressure product were lower in groups II and III. Thus there are significant differences in left ventricular systolic function both at rest and during exercise between these three major hemodynamic subgroups. These findings emphasize the importance of such a hemodynamic classification of HCM.

Adult↗
PubMed1984

Rest and exercise hemodynamic effects of sequential alpha-1-adrenoceptor (trimazosin) and beta-adrenoceptor (propranolol) antagonism in essential hypertension.

The efficacy of acute beta blockade in essential hypertension is limited by reflex vasoconstriction. The aim of this study was to determine whether the latter response was modified by prior selective alpha-1-adrenoceptor blockade. A single-blind, within-patient, placebo-controlled evaluation of the immediate hemodynamic effects of sequential alpha-1 (trimazosin)- and beta (propranolol)-adrenoceptor blockade was undertaken in 10 men (34 to 58 years) with previously untreated essential hypertension. The study commenced with a 4-minute control period of constant-load (600 to 900 kpm/min) upright bicycle exercise, and measurements were made before (control) and 30 minutes after intravenous trimazosin (2 mg/kg) and exercise was then repeated; measurements at rest were again made 4 minutes after intravenous propranolol (0.2 mg/kg) before a final exercise period. Trimazosin at rest reduced systolic and diastolic arterial pressure and systemic vascular resistance without change in heart rate, cardiac output, or left ventricular (LV) filling pressure. During upright bicycle exercise the reductions in blood pressure were sustained without change in their rest-to-exercise increments. Other circulatory variables did not differ from control values. At rest the addition of propranolol further reduced systolic arterial pressure. Heart rate and cardiac output fell and systemic vascular resistance increased to its pretreatment control value. During exercise the changes at rest were sustained and the rest-to-exercise increments in blood pressure, heart rate, and cardiac output were reduced. LV filling pressure was significantly increased. In conclusion, alpha-1-adrenoceptor blockade modified the adverse effects of acute beta blockade at rest but not during exercise.

Adult↗
PubMed1991

Correlation between resting ST segment depression, exercise testing, coronary angiography, and long-term prognosis.

Resting ST segment depression has been identified as a marker for adverse cardiac events in patients with and without known coronary artery disease. To correlate this with exercise testing, coronary angiography, and how it impacts on long-term prognosis, a retrospective study was performed on 476 patients, of whom 223 had no clinical or electrocardiographic evidence of prior myocardial infarction while 253 were survivors of an infarction. All patients performed a standard exercise test and underwent diagnostic coronary angiography within an average of 32 days of their exercise test (range 0 to 90 days). Exclusions were women, those with left bundle branch block, left ventricular hypertrophy, use of digoxin, previous revascularization procedures, or significant valvular or congenital heart disease. Long-term follow-up was carried out for an average of 45 months (+/- 17). Of the patients without prior infarction, 23 (10%) had persistent resting ST segment depression, and of those with a prior history of infarction, 37 (15%) also had resting ST segment depression. Patients with resting ST segment depression and no prior myocardial infarction had a higher prevalence of severe coronary disease (three-vessel and/or left main) (30%) than those without resting ST segment depression (16%) (95% confidence interval [CI] for observed difference -5.0% to 33.9%, p = 0.12). The criterion of greater than or equal to 2 mm of additional exercise-induced ST segment depression was a particularly useful marker in these patients for the diagnosis of any coronary disease (likelihood ratio 3.35, 95% CI 0.56 to 19.93, p = 0.06). Patients with resting ST segment depression and a prior myocardial infarction had a 2.5 times higher prevalence of severe coronary artery disease compared with patients without resting ST segment depression (43% versus 17% prevalence, respectively, 95% CI for observed difference 9.38% to 42.8%, p less than 0.001) and also had larger left ventricles postinfarction (left ventricular end-diastolic volume index 102 ml/m2 compared with 96 ml/m2, p less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)

Coronary Angiography↗
PubMed1985

Effects of training on systolic time intervals at rest and during isometric exercise in men and women 61 to 64 years old.

To determine whether regular exercise improves left ventricular (LV) contractile function in persons 60 years and older, systolic time intervals (STIs) were measured in 10 healthy men and women (mean age 62 +/- 1 year [+/- standard deviation]) before and after 6 months of intense endurance training. STIs, systolic and diastolic blood pressure (BP) and heart rate (HR) were determined at rest and in response to isometric handgrip exercise. Systolic BP, diastolic BP and HR increased acutely from rest in response to handgrip (p less than 0.002). The indexes of total electromechanical systole and LV ejection time (ET) index increased (p less than 0.01), preejection period (PEP) index increased (p less than 0.05) or remained unchanged and PEP/LVET did not change from values at rest in response to handgrip. Training resulted in an 18% increase in maximal oxygen uptake (p less than 0.01). After training, systolic and diastolic BP were reduced at rest (p less than 0.002) and, along with HR, were lower in response to handgrip (p less than 0.002). However, training did not alter STIs at rest or during handgrip. These findings indicate that healthy persons in their 60s have a normal LV response to isometric exercise. Prolonged, intense endurance training does not alter LV contractile function at rest or in response to isometric exercise. However, training can significantly reduce BP at rest, and markedly lower the HR-systolic BP product attained during acute isometric stress, even in normotensive older subjects.

Aged↗
PubMed1990

Alterations in the circadian rest-activity rhythm in aging and Alzheimer's disease.

The suprachiasmatic nucleus, considered to be the endogenous circadian clock in the mammalian brain, shows morphological changes with aging, which become even more pronounced in Alzheimer's disease (AD). In order to assess possible functional implications of these alterations, circadian rest-activity rhythms of 6 young and 13 old volunteers and of 12 AD patients were studied with a recently developed ambulatory rest-activity monitor (RA24). Young and old volunteers showed no differences in their rest-activity rhythm in any of the variables studied. Comparison of old controls versus AD patients revealed that (1) rest-activity rhythm was markedly disturbed in many of the AD patients and tended to be correlated with the severity of the dementia; (2) disturbances were most pronounced in subjects using sedating drugs; (3) disturbances in the latter group did not result from medication as no differences were found in the rest-activity patterns before and after administration of sedating drugs; (4) negative findings reported in the literature concerning circadian disturbances in AD may well have resulted from selection criteria that excluded the group of patients with the most severely affected rest-activity rhythm; and (5) rest-activity monitors offer a practical and fruitful approach for the study of circadian rhythms in humans.

Adult↗
PubMed1976

Resting and stimulated values of model parameters governing transmitter release at a synapse in Aplysia californica.

Transmitter release (R) at a synpase in Aplysia californica can be analyzed in terms of a model with the following parameters: A, the available pool of transmitter; F, the fraction of available pool released by a presynaptic action potential; M, the rate of transmitter mobilization into the available pool; D, the rate constant of demobilization of transmitter from the available pool. In the present paper we show that: (1) beginning with an analysis of the recovery from depression of the second of a pair of disolated EPSPs separated by a series of intervals of about 10-60 sec, and assuming that the recovery is due to refilling of a depleted A, it is possible to estimate resting equilibrium values of these parameters; (2) changes in these parameters when a new equilbrium state is reached after prolonged stimulation (e.g., 300 stimuli at 1/sec) can then be quantitatively determined; (3) the increased rate of transmitter release observed during and after repetitive stimulation is the consequence of increases in F and M with changes in A passively following; and (4) there are significant correlations among certain resting parameters and between the values of certain resting parameters and these parameters upon stimulation. Preparations with a large resting F tend to have a relatively small resting A. Preparations with a large resting F or M tend to increase these less with stimulation than preparations with smaller resting values of these parameters. Preparations with large stimulus-dependent increases in F tend to have large stimulus-dependent increases in M.

Animals↗
PubMed1995

Parkinson's disease rigidity: EMG in a small hand muscle at "rest".

The presence of excessive EMG at "rest" might be an important factor in the genesis of Parkinson's disease (PD) rigidity, and we studied it in the first dorsal interosseous muscle (FDI) of 8 idiopathic PD patients. We had 8 age- and sex-matched normal controls. In the PD group, the average area of the surface EMG at "rest" correlated significantly with the clinical evaluation of rigidity and remained abnormally enhanced for 10-15 min after a command to "relax." Later, it tended to decline, but its entity was still much greater than in controls. The EMG "at rest" consisted of unwilled motor unit (MU) firing. A larger MU number was recruited in patients than in controls at "rest." MU rate coding was similar in both groups. Eventually, patients could get periods of EMG silence which, however, were interrupted by short EMG bursts, even if there was no muscle stretch. These bursts were interpreted as residual fragments of the original excessive EMG at "rest." MUs first recruited during such bursts showed high, but not total, overlapping with those first recruited by a gentle voluntary contraction or by a weak transcranial magnetic stimulus to motor cortex. We conclude that EMG activity at "rest" was made up of the discharge of low-threshold MUs, with a recruitment order similar to that resulting from descending cortico-spinal volleys. However, we cannot exclude other possible input sources to the alpha-motoneurones at "rest."

Aged↗