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PubMedDate not supplied

[Serum activity of angiotensin-converting enzyme and osteocalcin levels in hyperthyroidism].

This study was carried out in order to investigate serum changes of osteocalcin (BGP) and angiotensin converting enzyme (SACE) activity in a group of patients with hyperthyroidism. We studied 20 hyperthyroid patients (F 14, M 6; age mean 37.5 +/- 16.8 years) and 13 control subjects (F 11, M 2; age mean 40.3 +/- 7.5 years). In both patients and controls we measured: FT3, FT4, T3, T4, TSH, BGP, SACE. Finally, in patients with hyperthyroidism a TRH test and functional investigations were also performed. We observed that mean SACE levels were significantly increased in hyperthyroid patients (32.06 +/- 10.3 nmol/ml/min) in respect to control subjects (14.66 +/- 3.88 nmol/ml/min) (p = 2.02 E-6). Similarly serum BGP levels were significantly increased in hyperthyroid patients (5.94 +/- 2.55 ng/ml) than in control subjects (2.89 +/- 1.58 ng/ml) (p = 5.66 E-4). There was a significant linear correlation between SACE and T4 levels (r = 0.48; p < 0.05), between serum BGP and T4 (r = 0.50; p < 0.02) and furthermore between SACE and BGP (r = 0.57; p < 0.01). In conclusion both serum BGP and SACE levels are increased in patients with hyperthyroidism and are directly correlated between than and with indexes of thyroid function; therefore, they may be regarded as peripheral indexes of hyperthyroidism.

Adult↗
PubMed1978

The haematology of hyperthyroidism.

In an unselected series of 239 patients with uncomplicated hyperthyroidism the haemoglobin concentration was less than 12.0 g/dl in 37 of 207 women and below 13.0 g/dl in 9 of 32 men. Although some of these patients with a low level of haemoglobin were iron deficient, with a transferrin saturation less than 16 per cent, many were not. On treatment of hyperthyroidism the haemoglobin rose by an average of 0.5 g/dl in patients who had not been anaemic on diagnosis. A small fall in haemoglobin is therefore usual in hyperthyroidism and it may sometimes be sufficient to cause a mild degree of anaemia. The mean corpuscular volume (MCV) was decreased in hyperthyroid patients who had neither anaemia nor a reduced transferrin saturation. After treatment of hyperthyroidism the MCV rose in these patients by an average of 6 fl. A dimunition in MCV, even within the normal range, is an invariable concomitant of hyperthyroidism. The administration of thyroxine to excess does not, however, cause the same change in the MCV. On diagnosis of hyperthyroidism the prevalence of pernicious anaemia in this series of patients was 1.9 per cent. Gastric parietal cell antibodies were present in 15.4 per cent and thyroid microsomal antibodies in 49.5 per cent.

Adolescent↗
PubMed1979

Pitfalls in the laboratory diagnosis of atypical hyperthyroidism.

When hyperthyroidism results from active thyroidal secretion, both serum hormonal levels and the radioactive iodine uptake (RAI) are elevated. Discordant results (increased serum hormone levels and a low RAI) are found either in the usual forms of hyperthyroidism when large quantities of iodide are ingested, or in atypical forms of hyperthyroidism, including spontaneously resolving hyperthyroidism of subacute thyroiditis, thyrotoxicosis factitia, toxic struma ovarii, and functioning metastatic thyroid cancer. Two patients are described who exemplify pitfalls in the interpretation of thyroid function test results in atypical hyperthyroidism. The following guidelines are helpful in avoiding these pitfalls: (1) An RAI should be performed in all thyrotoxic patients to confirm the presence of thyroidal hypersecretion, rather than atypical hyperthyroidism. (2) A positive response to thyroid-stimulating hormone stimulation is an important finding differentiating the other atypical forms of hyperthyroidism listed from subacute thyroiditis.

Adult↗
PubMed1976

[Thyroid cancers masked by hyperthyroidism. 12 cases].

The main object of this report was to attract again attention to the fact that obvious hyperthyroidism does not exclude the possibility of associated thyroid carcinoma, although this is an exceptional association. The 12 cases presented here may be added to about 30 cases found in the world literature. They were observed over a period of 13 years by the same surgical team and correspond to 0,3 p. 100 of all thyroid operations, 1 p. 100 of operated cases of hyperthyroidism and 3,6 p. 100 of cases of thyroid carcinoma. Contrary to most published cases, 11 or these cases out of 12, presented, clinically, mainly as hyperthyroidism the carcinotous lesion was either palpabale clinically in the form of a very small nodule (6 cases) or totally latent and discovered operation or even on histology as in 5 cases. Hyperthyroidism produced in 3 cases the classical picture of Graves' disease, in 6 cases that of toxic nodular goiter and, in 2 cases, that of a solitary toxic adenoma. The hyperplasia and the carcinoma were always in anatomically different areas. There is no apparent physiopahtological link and the classical notion of para-neoplastic hyperthyroidism seems debatable in most cases presented here, even in the cases of diffuse hyperfunctional hyperplasia. In any case, whatever the pathogenesis of this association, its possibility should be brought to mind in a case of hyperthyroidism. Surgery should always be advised in cases of toxic adenoma and in Graves' disease when the goiter is irregular and, especially, when a nodule is found. The course and prognosis seem to be mainly dictated by the histological type and the local spread or distant spread of the carcinoma, hyperthyroidism does not aggravate seriously the prognosis.

Adult↗
PubMedDate not supplied

Evidence for an active immune response in acute hyperthyroidism (Graves' disease).

Activated lymphocytes, identified by an autoradiographic labeling method, were found to be present in the peripheral blood of the majority of 20 patients with acute hyperthyroidism (Graves' disease). The number of such cells in the blood was significantly greater than that found in 30 healthy controls (p less than 0.00001), and in 13 patients who had previously suffered from acute hyperthyroidism, and who were judged to be euthyroid following therapy (p less than 0.025). This latter group included two patients in whom such activated lymphocytes had been found in the blood during the acute phase of their illness. Furthermore, there were significant differences between the number of such activated circulating lymphocytes in the group of patients with acute hyperthyroidism and five patients suffering from hyperthyroidism due to a toxic thyroid nodule (p less than 0.001), five patients suffering from primary myxedema (p less than 0.001), or in 14 patients with a nontoxic multinodular goiter (p less than 0.05). Identification and counting of circulating T and B lymphocytes by fluorescent immunolabeling and rosette-forming techniques in a small number of the patients with acute hyperthyroidism failed to reveal significant differences from the normal. The results suggest that in acute hyperthyroidism there is active stimulation of the cellular immune system, and that this effect is specific to the early, untreated phase of the disease. This response is different to other thyroid diseases, including hyperthyroidism due to a toxic thyroid nodule.

Adolescent↗
PubMed1977

Digoxin in hyperthyroidism.

A patient with chronic atrial fibrillation developed hyperthyroidism. Increasing doses of digoxin were required to maintain satisfactor ventricular rate control. The systemic availability of oral digoxin was decreased in this patient. The metabolism of digoxin was studied in the hyperthyroid rats. The plasma digoxin concentrations were significantly decreased in the hyperthyroid rats. A threefold increase in digoxin excretion in the bile of the hyperthyroid rats was associated with these changes in plasma digoxin concentrations. Conversely, hypothyroid rats excreted less digoxin in the bile when compared with control and hyperthyroid rats. Thus, changes in digoxin absorption and its biliary excretion result, in part, in a decreased therapeutic effect of digoxin based on dose in hyperthyroidism.

Animals↗
PubMed1992

Effect of hyperthyroidism of short duration on cardiac sensitivity to beta-adrenergic stimulation.

The effect of hyperthyroidism on cardiac sensitivity to beta-adrenergic stimulation in humans is controversial. To determine whether heart rate and left ventricular contractile sensitivity to beta-adrenergic stimulation are altered by hyperthyroidism in human subjects, the frequency, velocity and extent of left ventricular shortening at rest and during a 4-stage graded dose isoproterenol infusion were characterized in eight young healthy subjects before and after 2 weeks of daily administration of 100 micrograms of triiodothyronine (T3). The rate and extent of left ventricular shortening were determined by Doppler and two-dimensionally guided M-mode echocardiography. In the hyperthyroid state, heart rate at rest was faster (57 +/- 3 vs. 68 +/- 4 beats/min; p less than 0.001) and the slope of the relation of heart rate to the rate of isoproterenol infusion was 36% steeper (1,538 +/- 126 vs. 1,131 +/- 95; p less than 0.05). The left ventricular ejection time was shorter and the mean velocity of left ventricular circumferential fiber shortening (mVcf) was greater during all stages of isoproterenol infusion in the hyperthyroid versus the euthyroid state (p less than 0.01). After adjustment for the faster heart rate after T3 administration, left ventricular ejection time and mVcf were similar in the euthyroid and hyperthyroid states at baseline and during maximal beta-adrenergic stimulation but shortened and enhanced, respectively, during stages 1 and 2 of isoproterenol infusion (p less than 0.05). There was no effect of T3 administration on left ventricular mass, dimensions, end-systolic wall stress or stroke volume at rest or during any stage of isoproterenol infusion. These results indicate that in human subjects hyperthyroidism of short duration increases the sensitivity of heart rate and left ventricular shortening velocity to beta-adrenergic stimulation in the absence of changes in left ventricular mass, loading conditions or extent of shortening.

Administration, Oral↗
PubMed1975

Hormonal pattern of relapse in hyperthyroidism.

22 patients with Grave's disease were followed up for up to a year after antithyroid drug therapy was discontinued. Clinical assessment and serum T3, T4, and thyroid-stimulating-hormone (T.S.H.) estimations were done serially and simultaneously. Serum T3 or T4 concentrations may be elevated briefly in the first few weeks after antithyroid drugs are stopped, as a rebound effect not necessarily indicative of subsequent relapsf. Clinical relapse of hyperthyroidism with subsequent improvement on antithyroid drugs occurred in 13 patients. Of these 13, serum T3 concentrations became elevated before serum T4 concentrations in 5, thus predicting the subsequent development of clinical hyperthyroidism. In the remaining 8 patients who relapsed, serum T4 was elevated a month before the serum T3. Hyperthyroidism was diagnosed clinically after elevated serum T3 concentrations in 11 patients and at the same time in 2 patients. The mean period of "biochemical hyperthyroidism" in these 11 patients was 12 weeks, with a range of 1 to 56 weeks. During this period 9 of the 11 had minor clinical changes attributable to hyperthyroidism. It is concluded that serial estimations of serum T3 provide the most reliable method of monitoring relapse in hyperthyroidism.

Carbimazole↗
PubMed1976

Influence of hyperthyroidism on glycerol-extracted cardiac muscle from rabbits.

The mechanism responsible for the enhancement of myocardial contractility in hyperthyroidism is unclear. The possibility that this mechanism may involve a direct effect on the contractile proteins was investigated using the glycerol-extracted muscle strip from right ventricular papillary muscles of euthyroid rabbits and rabbits made hyperthyroid by the intraperitoneal injection of 0.25 mg/kg 1-thyroxine for 10 d. Intact papillary muscles from the hyperthyroid rabbits had an enhanced rate of tension development, a decreased time to peak tension, and a slight though insignificant increase in active tension compared to control animals. Maximal isometric contractions were induced in glycerol-extracted cardiac muscle strips from the two animal groups by the addition of 5 mmol/litre ATP and 5 mmol/litre MgCl in a buffer solution containing 0.15 mol/litre Tris-HCl (pH 7.1) at 26 degrees C. Peak isometric tension was increased in glycerinated muscle strips from hyperthyroid rabbits (1.52+/-0.10 vs 1.26 +/-0.13g/mm2), but the differences did not reach statistical significance. However, there was a marked increase in the rate of tension development in the hyperthyroid group (62.5+/-5.4 vs 41.8+/-4.7 mg/mm-2/s, P less than 0.01). This increase in the rate of isometric tension development in both intact and glycerinated muscles from hyperthyroid rabbits may be related to changes in the intrinsic turnover of actomyosin cross-bridge links in this condition. Thus, these findings suggest that thyroid hormone may influence cardiac muscle function by a direct effect on the contractile proteins.

Adenosine Triphosphate↗
PubMed1979

The influence of hyperthyroidism and hypothyroidism on the beta-adrenergic responsiveness of the turkey erythrocyte.

The mechanisms responsible for altered adrenergic tone in hyperthyroidism and hypothyroidism are not fully understood. To investigate these mechanisms, the beta-adrenergic receptor-cyclic AMP complex of the turkey erythrocyte was studied among groups of normal, hyperthyroid, and hypothyroid turkeys. In erythrocytes obtained from hypothyroid turkeys, there were fewer beta-adrenergic receptors than in normal cells as determined by the specific binding of [(125)I]iodohydroxybenzylpindolol, as well as associated decreases both in catecholamine-responsive adenylate cyclase activity and in cellular cyclic AMP content. In contrast, erythrocytes obtained from hyperthyroid turkeys contained the same number of beta-receptors and had the same catecholamine-responsive adenylate cyclase activity as cells from normal birds. Other characteristics of the beta-receptors in cells from hyperthyroid birds were indistinguishable from those present in normal erythrocytes. However, within the range of circulating catecholamine concentrations, 5-50 nM, the erythrocytes of the hyperthyroid turkeys generated substantially more cyclic AMP after exposure to isoproterenol than did normal cells. These results suggest that thyroid hormone affects beta-receptor-cyclic AMP interrelationships in the turkey erythrocyte by two distinct mechanisms: (a) In hypothyroidism, both beta-receptors and catecholamine-dependent cyclic AMP formation are coordinately decreased; (b) in hyperthyroidism, beta-receptors are unchanged but there is an amplification of the hormonal signal so that occupation of a given number of receptors at physiological concentrations of catecholamines leads to increased levels of cyclic AMP.

Adenylyl Cyclases↗
PubMed1976

Catecholamines metabolism in thyroid diseases. I. Epinephrine secretion rate in hyperthyroidism and hypothyroidism.

We have measured the secretion rate of epinephrine in 6 euthyroid, 6 hyperthyroid, and 6 hypothyroid subjects infused at a constant rate for a one hour period with tritiated epinephrine (.01 muc/kg/min) (New England Nuclear Inc.). Plasma and urinary levels of epinephrine were measured by modifying the fluorometric method of Anton and Sayre. Plasma levels of epinephrine were 3.0 +/- 3.0 ng/100 ml (mean +/- SD) in normal subjects, compared to 4.4 +/- 3.5 ng/100 ml (mean +/- SD) in hyperthyroid subjects. In urine, epinephrine values ranged from 1.3 mug/day to 6.1 mug/day in normal subjects. Mean value observed in hyperthyroidism was 4.9 +/- 2.6 mug/day and 3.8 +/- 1.0 mu/day in hypothyroidism. Plasma secretion rates averaged 48 +/- 27 mug/kg/day in normal subjects, compared to 54 +/- 18 mu/kg/day in hyperthyroidism and 43 +/- 20 mug/kg/day in hypothyroidism. Likewise, the mean urinary secretion rate was 55 +/- 27 mug/kg/day in normal subjects compared to 60 +/- 22 mug/kg/day in hyperthyroidism and 50 +/- 28 mug/kg/day in hypothyroidism. There is no statistical difference between the values found in the three groups of subjects (plasma and urine). Therefore, these results would indicate that the signs and symptoms encountered in hyperthyroidism are not secondary to a high secretion rate of epinephrine.

Epinephrine↗
PubMed1992

Galanin does not affect the growth hormone-releasing hormone-stimulated growth hormone secretion in patients with hyperthyroidism.

Patients with hyperthyroidism have reduced spontaneous and stimulated growth hormone (GH) secretion. The aim of our study was to evaluate the effects of galanin, a novel neuropeptide which stimulates GH secretion in man, on the GH response to GHRH in patients with hyperthyroidism. Eight untreated hyperthyroid patients with Graves' disease (6F, 2M, aged 25-50 years) and six healthy volunteers (3F, 3M, aged 27-76 years) underwent from -10 to 30 min in random order: (i) porcine galanin, iv, 500 micrograms in 100 ml saline; or (ii) saline, iv, 100 ml. A bolus of human GHRH(1-29)NH2, 100 micrograms, was injected iv at 0 min. Hyperthyroid patients showed blunted GH peaks after GHRH+saline (10.2 +/- 2.5 micrograms/l) compared to normal subjects (20.7 +/- 4.8 micrograms/l, p < 0.05). GH peaks after GHRH+galanin were also significantly lower in hyperthyroid subjects (12.5 +/- 3 micrograms/l) compared to normal subjects (43.8 +/- 6 micrograms/l, p < 0.05). That galanin is not able to reverse the blunted GH response to GHRH in hyperthyroidism suggests that hyperthyroxinemia may either increase the somatostatin release by the hypothalamus or directly affect the pituitary GH secretory capacity.

Adult↗
PubMed1978

Age-related glucose intolerance in hyperthyroid patients.

In an attempt to study age-related metabolic abnormalities, glucose intolerance and serum insulin were examined in normal subjects and hyperthyroid patients. For comparison, serum concentrations of thyroxine (T4), triiodothyronine (T3), and total cholesterol were also measured in normal subjects and hyperthyroid patients. Although serum T4 concentration remained unchanged, serum T3 concentration decreased significantly in an elderly group of normal subjects. Similarly, serum T4 did not change with age and serum T3 decreased slightly but progressively with age in hyperthyroid patients. In addition, serum total cholesterol concentration increased progressively with age in normal subjects. Oral glucose tolerance decreased with age in normal subjects despite the same timing, peak level attained, and total magnitude of insulin response for old and young subjects. Although the severity of hyperthyroidism decreases with age, age-related glucose intolerance was much more apparent in hyperthyroid patients because of the age-related decrease of basal concentration, the peak level attained, and the total magnitude of insulin response. It is suggested that age-related glucose intolerance is magnified by the hyperthyroid state.

Adolescent↗
PubMed1979

Bone mineral content in hyperthyroid patients after combined medical and surgical treatment.

Bone mineral content (BMC) and bone mineral concentration (BMC') of the forearm were determined by photon absorptiometry in 20 untreated hyperthyroid patients and in 33 patients previously treated for hyperthyroidism. In untreated hyperthyroidism a significant decrease was found in both BMC and BMC'. In treated hyperthyroidism BMC and BMC' were normalized. The findings suggest that a previous hyperthyroid state is not a risk factor for development of spontaneous fractures providing the hyperthyroid state is effectively treated.

Adult↗
PubMed1992

Cyclic AMP infusion and blood sugar, serum insulin and serum nonesterified fatty acid responses to glucose in recent experimental hyperthyroid dogs.

Recent experimental hyperthyroid (REH) dogs exhibit poor "in vivo" insulin responses to glucose probably due to a failure somewhere in cAMP-adenylate cyclase system. The actions of exogenous cAMP on these responses and on the regulation of blood sugar (BS) and serum nonesterified fatty acids (NEFA) during glucose infusion tests (GIT) in REH and normal dogs were studied here. Hyperthyroidism was induced by 1-thyroxine administration (100 micrograms/kg body wt./die, 10 days). GIT consisted of i.v. glucose-priming followed by glucose i.v. continuous infusion (60 min). cAMP (0, 33 or 66 mg/kg body wt./min) was infused alone (30 min) and then overlapped to gluco-se infusion (60 min). Peripheral veins were used for infusions and blood sample withdrawal. BS, serum inmunoreactive insulin (IRI) and serum NEFA concentrations, basally and throughout the test, were measured. Basally, there was neither action nor interaction of hyperthyroidism and exogenous cAMP on these variables. During the GIT, the BS levels remained unaffected by hyperthyroidism; cAMP increased them, but failed to interact with hyperthyroidism. cAMP noninfused normal dogs responded to hyperglycemia with hyperinsulinemia, whereas REH dogs noninfused the nucleotide did not. cAMP administration at a high dose promoted their response in normal and REH dogs, particularly in the former; in the latter, the response was still lower than in cAMP noninfused normal controls. Although recent hyperthyroidism increased serum NEFA basal level, it exerted neither action nor interaction with the infused cAMP on serum NEFA during GIT. Results are discussed on the basis that the abolished insulin secretion "in vivo" characterizing the REH dogs, related to beta-adrenergic deficiency, can be for the most part restored by exogenous cAMP administration, despite which some glucose and triglyceride metabolism impairments are developed.

Animals↗
PubMed1976

[Dose-response relationship in radioiodine therapy of hyperthyroidism].

For the analysis of the dose-response relationship during radioiodine therapy, the effective dose was calculated based on measurements in 1171 patients in the course of treatment. Early results of the radioiodine therapy of these cases were checked up from six to nine months afterwards. The probability of incidence of a residual hyperthyroidism or of the induction of hypothyroidism respectively, in dependence on dosage, is represented by a dose-response curve. The dose-response curve for residual hyperthyreoses shows an exponential shape, whereas the curve of induced hypothyroidism is sigmoidally shaped. The results of experimental biophysics concerning dose-response curves allow the statement that there is no reactivity of the thyroid gland in cases of residual hyperthyroidism, whereas distinct compensation mechanisms are counteracting the induction of hypothyroidism. Thus, the conception of fractionated radioiodine therapy is supported by the shape of dose-response curves. The fractionation of the dose leads to accumulated inactivation effects on the hyperthyroidism, while the compensational mechanisms against hypothyroidism are strengthening by intermittent recovery and the rate of induced hypothyroidism is decreasing. The favorable effect of multiple treatment on the number of induced hypothyreoses could be verified by our own material. During the radioiodine therapy of hyperthyroidism, a defined interrelation is found between the effective dose, the thyroid mass and the effect of the dose. A formula of the isoeffective dose in dependence of the thyroid mass is derived analogically to percutaneous radiation therapy. The deviation of the effective dose from the dose previously calculated is represented as a distribution function. The mean value of this distribution function can be regarded as an expectation of the effective dose. Hence, a previous calculation of the dose is considered useful also in future. The isoeffective dose is proposed to be chosen in dependence on the thyroid mass according to a fifty-per-cent-probability of residual hyperthyroidism. Relative to the intensity of residual hyperthyroidism, a second treatment considering the same standards should be performed after four to nine months. The number of reiterated treatments needed depends on individual radiation sensitivity resulting from biological factors.

Dose-Response Relationship, Radiation↗
PubMed1992

Studies on the association of NIDDM in Japanese patients with hyperthyroid Graves' disease.

We attempted to analyze the association of hyperthyroid Graves' disease with non-insulin-dependent diabetes mellitus (NIDDM). Forty-nine patients (23 males and 26 females; 7.6%) of a total of 647 patients with hyperthyroid Graves' disease had NIDDM, several years before or after Graves' disease was diagnosed. Only 1 patient had insulin-dependent diabetes mellitus. Compared with the general Japanese population (n = 9,133), the incidence of NIDDM (n = 348; 3.9%) in patients with Graves' disease was higher in all age groups. Only 4 patients (8.2%) of the 49 hyperthyroid patients with NIDDM had a history of being overweight (body mass index > 25). In contrast, 276 (79.9%) of the 348 diabetic patients were currently or previously overweight. Moreover, the incidence of a family history of diabetes (13 of the 49 hyperthyroid Graves' patients with NIDDM; 26.5%) was also lower in the patients with NIDDM in the general Japanese population (50% incidence). The male:female ration in patients with Graves' disease and NIDDM was 1:1.1; much different from that in the total Graves' disease population (1:4.1). Analysis of the HLA loci A, B, C, DR and DQ (35 determinations) in 35 hyperthyroid patients with NIDDM and in 386 subjects from the general population revealed a highly significant difference between them in the incidence of HLA-Cw4, -DR2, -DQw1, -DQw3 and -DQw4. This study suggests that there was an association of Graves' disease with NIDDM. A significant association of HLA-DR and -DQ loci was observed in hyperthyroid Graves' patients with NIDDM.

Adolescent↗
PubMedDate not supplied

Experimental hyperthyroidism III: Contractile responses to propranolol of the intact heart and of the isolated ventricular myocardium.

The effect of propranolol on cardiac mechanics and haemodynamics was examined on isolated papillary muscle as well as in situ in the closed thorax in euthyroid and hyperthyroid cats. Under propranolol there occurred on isolated papillary muscle significant decreases of muscle contraction, contraction velocity, isometric tension rise velocity and load and velocity values of simultaneously determined force-velocity relations. The 50% decrease of the values found was demonstrable at ca. 5--8 mu/ml for euthyroidal muscles, at 0.3--0.5 mug/ml for hyperthyroidal muscles. Contractility indices determined in situ (dp/dtmax, VCEmax, extrapolated Vmax) showed in hyperthyroidism at equal propranolol concentration a decrease about twice as great as in euthyroidism. The findings, showing a raised responsiveness of the ventricular myocardium in experimental hyperthyroidism to the negative inotropic effect of propranolol are discussed with regard to the therapeutic use of propranolol in hyperthyroidism.

Aged↗