Accumulation of p27(kip1) is associated with cyclin D3 overexpression in the oxyphilic (Hurthle cell) variant of follicular thyroid carcinoma.

BACKGROUND: The down regulation of protein p27(kip1) (p27) in most cases of thyroid cancer has relevant diagnostic and prognostic implications. However, the oxyphilic (Hurthle cell) variant of follicular thyroid carcinoma expresses more p27 than benign oxyphilic lesions do. AIM: To evaluate the mechanism underlying this difference in expression of p27. METHODS: Because high levels of cyclin D3 lead to p27 accumulation in cell lines and clinical samples of thyroid cancer, the immunocytochemical pattern of cyclin D3 in oxyphilic (n = 47) and non-oxyphilic (n = 70) thyroid neoplasms was investigated. RESULTS: In the whole study sample, there was a significant correlation between p27 and cyclin D3 expression (Spearman's r: 0.64; p<0.001). The expression of cyclin D3 and p27 was significantly higher in the oxyphilic variant of follicular carcinomas than in non-oxyphilic carcinomas (p<0.001). In the former, cyclin D3 overexpression and p27 accumulation were observed in a median of 75% and 55% of cells, respectively. In co-immunoprecipitation experiments, the level of p27-bound cyclin D3 was much higher in oxyphilic neoplasias than in normal thyroids and other thyroid tumours. CONCLUSION: These results show that increased p27 expression in the oxyphilic (Hurthle cell) variant of follicular thyroid carcinoma results from cyclin D3 overexpression.

Pain relief in early rehabilitation of rotator cuff tendinitis: any role for indirect suprascapular nerve block?

AIM: The purpose of the trial was to evaluate the efficacy of suprascapular nerve block (SSNB) to relieve the shoulder pain, ameliorate recovery after physiotherapy and reduce disability due to a rotator cuff tendinitis (RCT). A prospective, randomized, comparison cross over investigation was performed in the setting of a large inpatient rehabilitation unit with more than 200 admissions annually. METHODS: A total of 40 potential study subjects, who complained of shoulder pain from a RCT, were enrolled and randomly assigned to standard rehabilitation treatment plus SSNB (Group A) or to standard rehabilitation treatment alone (Group B). The UCLA shoulder rating scale was used to assess the shoulder mobility on admission and discharge, and to calculate the percentage of potential improvement achieved during rehabilitation (effectiveness). A pain visual analogic scale was used to serially assess pain. At the end of the trial, a self-report questionnaire evaluated whether patients could sleep and achieve activity of day life carry out everyday activities better than they could before treatment. RESULTS: Forty patients suffering from RCT entered the study. Those receiving nerve block from the beginning of the treatment in addition to standard rehabilitation therapy reported significantly less pain during physiotherapy and better final outcomes. During treatment with SSNBs, patients reported a more significant reduction in the intensity of pain and a better reduction of pain during sleep and rehabilitation exercises in comparison to with the standard therapy alone. A statistically significant inverse correlation was found between shoulder pain and mobility. CONCLUSIONS: The results indicate that combining nerve block with standard rehabilitative therapy may improve the final outcome of painful RCT. It decreased the severity and frequency of the perceived pain, improved the compliance with physiotherapy, restored more normal sleep patterns, and increased compliance with the rehabilitation program. This result proves to be an effective, safe and inexpensive therapeutic option for patients suffering from painful disabling shoulder tendinitis.

Hybrid association between human apolipoproteins A-I and A-II in aqueous solution and in phospholipid recombinants.

The formation of hybrid association products between apolipoprotein A-I and apolipoprotein A-II from human high-density lipoprotein was investigated in solutions of these apolipoprotein and in recombinant particles with dimyristoylphosphatidylcholine (DMPC). It was found that these two proteins interact in solution to form hybrid association products, but not to a marked degree. When these two proteins were incubated together with DMPC, it was likewise found that there was little tendency to reside on the same particle, as judged from the absence of hybrid oligomers by chemical cross-linking. By a modified immunoelectrophoretic method it was found that only about 15% of the A-II and 10% of the A-I were precipitated by the heterologous antiserum; from this it is concluded that 80-90% of these proteins do not form hybrid recombinants with the other protein. These results suggest that in the delipidated state, as well as in discoidal recombinants, there do not exist strong protein-protein interactions between A-I and A-II. This implies that even in the high-density lipoprotein, where both proteins coexist in the same particle, the A-II does not stabilize the molecular structure through interactions with A-I, and its role in this molecule remains obscure.

Endogenous subclinical hyperthyroidism affects quality of life and cardiac morphology and function in young and middle-aged patients.

To determine the clinical impact of endogenous subclinical hyperthyroidism, specific symptoms and signs of thyroid hormone excess and quality of life were assessed in 23 patients (3 males and 20 females; mean age, 43 +/- 9 yr) and 23 age-, sex-, and lifestyle-matched normal subjects by using the Symptoms Rating Scale and the Short Form 36 Health Survey questionnaires. Because the heart is one of the main target organs of the thyroid hormone, cardiac morphology and function were also investigated by means of standard 12-lead electrocardiogram (ECG), 24-h Holter ECG, and complete Doppler echocardiography. Stable endogenous subclinical hyperthyroidism had been diagnosed in all patients at least 6 months before the study (TSH, 0.15 +/- 0.1 mU/L; free T(3), 6.9 +/- 1.1, pmol/L; free T(4), 17.2 +/- 2.3, pmol/L). Fifteen patients were affected by multinodular goiter, and eight patients by autonomously functioning thyroid nodule. The mean Symptoms Rating Scale score (9. 8 +/- 5.5 vs. 4.3 +/- 2.2, P: < 0.001) and both the mental (36.1 +/- 9.5 vs. 50.0 +/- 8.5, P: < 0.001) and physical (42.6 +/- 8.0 vs. 55. 6 +/- 4.1, P: < 0.001) component scores of Short Form 36 Health Survey documented a significant prevalence of specific symptoms and signs of thyroid hormone excess and notable impairment of quality of life in patients. Holter ECG showed a higher prevalence of atrial premature beats in endogenous subclinical hyperthyroid patients than in the controls, but the difference was not statistically significant, although the average heart rate was significantly increased in the patients (P: < 0.001). An increase of left ventricular mass (162 +/- 24 vs. 132 +/- 22 g, P: < 0.001) due to the increase of septal (P: = 0.025) and posterior wall (P: = 0.004) thickness was observed in patients. Systolic function was enhanced in patients as shown by the significant increase of both fractional shortening (P: = 0.005) and mean velocity of heart rate-adjusted circumferential fiber shortening (P: = 0.036). The Doppler parameters of diastolic function were significantly impaired in the patients as documented by the reduced early to late ratio of the transmitral flow velocities (P: < 0.001) and the prolonged isovolumic relaxation time (P: = 0.006). These data indicate that endogenous subclinical hyperthyroidism has a relevant clinical impact and that it affects cardiac morphology and function. Moreover, they suggest that treatment of persistent endogenous subclinical hyperthyroidism should be considered also in young and middle-aged patients to attenuate specific symptoms and signs of thyroid hormone excess, ameliorate the quality of life, and avoid the consequences to the heart of long exposure to a mild excess of thyroid hormone.

Left ventricular diastolic dysfunction in patients with subclinical hypothyroidism.

Although subclinical hypothyroidism is frequently diagnosed, the decision to institute a substitutive therapy with L-T4 remains controversial. Because the cardiovascular system is considered a main target for the action of thyroid hormone, we investigated whether subclinical hypothyroidism induces cardiovascular abnormalities. Twenty-six patients (mean age, 36 +/- 12 yr) were evaluated by Doppler-echocardiography, whereas a subgroup of 10 patients, randomly selected, were reevaluated after 6 months of L-T4 substitutive therapy (mean dose, 68 microg daily). Thirty subjects (matched for age, sex, and body surface area) served as controls. Mean plasma TSH was significantly higher in patients (P < 0.001), whereas mean serum free T4 and free T3 concentrations, although in the normal range, were significantly lower (P < 0.001 and P < 0.005, respectively). Blood pressure and heart rate did not differ from control values. Echocardiogram examination showed no abnormalities of the left ventricular morphology and a slight, but not significant, reduction in the systolic function in the patient group. In contrast, Doppler-derived indices of diastolic function showed significant prolongation of the isovolumic relaxation time (94 +/- 13 vs. 84 +/- 8 msec; P < 0.001), increased A wave (55 +/- 13 vs. 48 +/- 9 cm/sec; P < 0.05), and reduced early diastolic mitral flow velocity/late diastolic mitral flow velocity ratio (1.4 +/- 0.3 vs. 1.7 +/- 0.3; P < 0.001). In the subgroup of 10 patients, thyroid hormone profile was normalized by 6 months of L-T4 substitutive therapy, whereas no changes were observed in the left ventricular morphology. Systolic function was significantly enhanced, as compared with pretreatment values (P < 0.01) but did not differ from control values. Also, systemic vascular resistance was significantly decreased by L-T4 replacement therapy. Assessment of diastolic function showed significant shortening of isovolumic relaxation time (77 +/- 15 vs. 91 +/- 8; P < 0.05), reduction of A wave (51 +/- 13 vs. 60 +/- 12; P < 0.01), and increase of early diastolic mitral flow velocity/late diastolic mitral flow velocity ratio (1.7 +/- 0.4 vs. 1.3 +/- 0.3; P < 0.001). These indices, however, were comparable with those of control subjects. These findings indicate that subclinical hypothyroidism affects diastolic function and that this abnormality may be reversed by L-T4 substitutive therapy.

Cardiovascular effects of short-term growth hormone hypersecretion.

Many studies have shown that acromegaly has relevant effects on cardiovascular system, but few data are available regarding the effects of short-term acromegaly on heart morphology and function. These data would help to clarify the natural history of acromegalic disease and could provide new insight into the mechanisms of GH action on the human heart. Therefore, we studied by Doppler echocardiography a group of 10 young subjects strictly selected as having short-term (<5 yr) uncomplicated acromegaly. The results of this study have shown that shortterm acromegaly is characterized by significantly increased left ventricular mass (P<0.005), with normal relative wall thickness, associated with Doppler indices of diastolic function in the normal range. Furthermore, stroke index and cardiac index were significantly enhanced in the patient group (P<0.01 and P<0.001, respectively), whereas systemic vascular resistance was significantly reduced (P<0.001). In conclusion, our study shows that short-term acromegaly significantly affects the heart, but, at variance with long-term disease, it is characterized by increased left ventricular mass, with eccentric remodeling and normal diastolic function. Moreover, short-term acromegaly induces a high cardiac output state with reduction of systemic vascular resistance.

A simplified procedure for the preparation of MHC/peptide tetramers: chemical biotinylation of an unpaired cysteine engineered at the C-terminus of MHC-I.

Recently, a powerful approach for the detection of MHC/peptide-specific T cells has been made possible by the engineering of soluble-tetrameric MHC/peptide complexes, consisting of singly biotinylated MHC/peptide molecules bound to fluorescent-labeled streptavidin. These tetrameric molecules are thought to compensate for the low affinity and relative fast dissociation rate of the TCR/MHC-peptide interaction by increasing the avidity of this interaction, thus allowing the stable binding of MHC/peptide tetramers to TCR expressing cells. Here we describe a new more simplified procedure for obtaining MHC/peptide tetramers using the well-characterized H-2K(b)/VSV system. This procedure consists of the incorporation of an unpaired cysteine residue at the C-terminus of the H-2K(b) molecule, allowing site-specific biotinylation by a -SH-specific biotinylating reagent. The H-2K(b)/VSV tetramers bound only to hybridomas expressing H-2K(b)/VSV-specific TCRs. When coated on a plate, these tetramers were able to induce IL-2 release by those hybridomas. Furthermore, H-2K(b)/VSV tetramers bound to CTL populations obtained from mice immunized with VSV-peptide. The specificity of the binding was further refined by studying cross-recognition of VSV by CTL populations obtained from mice immunized with single amino acid substituted VSV peptide variants. H-2K(b)/VSV tetramers bound only to those CTL populations that cross-reacted with the wild-type VSV peptide. Our method provides a simple, efficient and inexpensive procedure for making MHC/peptide tetramers, a highly specific and very useful reagent with a number of important applications in basic and clinical T cell research.

Myocardial contractility and total arterial stiffness in patients with overt hyperthyroidism: acute effects of beta1-adrenergic blockade.

OBJECTIVES: To ascertain whether myocardial contractility and total arterial stiffness are significantly altered in human thyrotoxicosis, and to what extent they are affected by acute beta(1)-adrenergic blockade. METHODS: Doppler-echocardiography was used to assess left ventricular (LV) structure and function, hemodynamics and total arterial stiffness in untreated overt hyperthyroid patients before and 2 h after 5 mg bisoprolol given orally compared with age- and sex-matched healthy euthyroid controls. RESULTS: Compared with controls, untreated patients (n=20) had a higher heart rate (HR) and LV stroke index (SI), which were associated with higher pulse pressure (PP), larger LV end-diastolic volume index (EDVI, an index of preload,+11%, P<0.05), marginally increased stress-corrected LV midwall fractional shortening (MWS, an index of myocardial contractility,+5%; P=0.066), and shorter isovolumic relaxation time (IVRT). These changes resulted in a higher cardiac index (CI) and a lower systemic vascular resistance (SVR), which were associated with fairly normal mean blood pressure (BP) but higher PP/stroke volume (an index of total arterial stiffness,+29%; P<0.01). After bisoprolol, compared with controls, the randomly treated patients (n=10) had comparable HR but additionally increased SI; PP remained enhanced, EDVI was further enlarged (+26%, P<0.001), stress-corrected MWS was substantially unchanged, and IVRT remained shorter. Overall, these effects attenuated the high-output state, which was associated with normalization of PP/stroke volume without changes of mean BP. CONCLUSIONS: In human overt hyperthyroidism, myocardial contractility does not play a major role in increasing LV performance, which is instead predominantly sustained by increased preload with enhanced LV diastolic function. In addition, human thyrotoxicosis is associated with increased total arterial stiffness despite fairly normal mean BP. In this scenario, acute beta(1)-adrenergic blockade blunts the cardiovascular hyperkinesia predominantly by slowing HR - a process that is associated with normalization of total arterial stiffness.

Relationships between fasting plasma insulin, anthropometrics, and metabolic parameters in a very old healthy population. Associazione Medica Sabin.

Several studies have shown that insulin resistance and hyperinsulinemia are associated with many metabolic disorders predisposing to coronary heart disease (CHD). This syndrome has been termed syndrome X. However, it is not completely known whether these relationships are still present in the elderly, or whether other factors such as age, gender, and body fat distribution modulate them. Therefore, we investigated the relationship between fasting plasma insulin, total and regional adiposity, fasting plasma glucose and lipids, plasma plasminogen activator inhibitor-1 (PAI-1), fibrinogen, and coagulation factor VII in a sample of 100 healthy free-living octogenarians-nonagenarians (52 men and 48 women) who were disability-free according to the Katz index. By univariate analysis, fasting insulin correlated positively with all anthropometric measures except the waist to hip ratio (WHR) in women. There was a positive correlation between fasting insulin and fasting glucose (r=.40, P < .01), plasma triglycerides ([TGs] r=.21, P < .05), and PAI-1 levels (r=.33, P < .01), whereas a negative relation was found with high-density lipoprotein cholesterol (HDL-C) and apolipoprotein, A-I (apo A-I) levels (r=-.22 and =-.24, respectively, P < .05). These relationships were weaker and less significant in women. In pooled data, stepwise multiple regression analysis showed an independent relationship of both the body mass index (BMI) and fasting insulin level with TGs (R2=.14), while gender and fasting insulin were the best predictors of HDL-C variance (R2=.17). Furthermore, fasting insulin was the only variable independently related to PAI-1 (R2=.12). Our findings support the existence of a metabolic syndrome even in very old age by showing that high insulin levels are related to various metabolic and hemostatic disorders.

Doxorubicin-induced cardiomyopathy treated with carvedilol.

Even today, heart failure due to doxorubicin-induced dilated cardiomyopathy seems to have a poor prognosis, as it is often irreversible and relatively unresponsive to standard medical treatment. This paper describes the first case of a patient complaining of severe symptoms of congestive heart failure due to doxorubicin-induced dilated cardiomyopathy unresponsive to standard medical treatment (digoxin, diuretics, and angiotensin-converting enzyme inhibitor), who showed complete clinical recovery and significant improvement of left ventricular dysfunction after carvedilol treatment. It also illustrates the possibility that carvedilol may be a first-choice drug for the treatment of this disease.

Lipoprotein profile, diet and body composition in athletes practicing mixed an anaerobic activities.

OBJECTIVE: To compare lipoprotein profile, body composition and diet in a sample of athletes practicing mixed and anaerobic sports activities, and in a group of sedentary controls. EXPERIMENTAL DESIGN: Cross selectional study. PARTICIPANTS: Twenty professional soccer players (mixed trained), twenty body builders (anaerobic trained) and twenty sedentary subjects, all males and matched for age were studied. RESULTS: No significant differences in total serum cholesterol, triglycerides, HDL-C, LDL-C, apolipoprotein A-I, A-II, B, C-II, C-III, and E levels were found when the three groups were compared. Bioelectrical impendance analysis disclosed significantly lower body fat percentages in both groups of athletes, and increased fat free mass only in body builders. Daily calorie intake was higher, and alcohol intake was lower in the athletes, compared with controls. Body builders had lower carbohydrate, and higher protein and cholesterol intakes, while soccer players had a lower polyunsaturated to saturated fat ratio. None of the apolipoproteins examined was correlated with any body composition of diet parameters. No correlations between lipid parameters and anthropometric or dietary variables were found by multivariate analysis when the subjects were considered as a whole. CONCLUSIONS: Our data suggest that in healthy lean normolipemic males, the lipoprotein profile is not modified by mixed or anaerobic sport activities and the respective modifications in body composition and diet.

[Changes in the building stones of Venice: action of atmospheric sulfur on carbonic rocks]. / Caratteri dell'alterazione delle pietre da costruzione in Venezia: azione dello zolfo atmosferico su rocce carbonatiche.

Analytical investigations were carried out on alteration crusts of "Pietra d'Istria" used for the construction of "Palazzo Papadopoli" in Venice. The chemical and mineralogical analyses of the microstructure showed that alteration process in mainly caused by the transformation of calcium carbonate into calcium sulphate and that the greatest damages are due to the subsequent detaching of sulphatic crusts according to a weakness surface. The isotopic analyses showed that sulphur present in the crust is mainly derived from the combustion of hydrocarbons. The investigations on the climatic conditions showed the meaningful importance of the climate parameters on described alterations.

The relative contributions of menopause and aging to postmenopausal reduction in intervertebral disk height.

AIM: To evaluate, in a population of normal women, the effects of aging and menopause on the height of intervertebral discs by measuring the intervertebral disk space, between the 12th thoracic and 4th lumbar vertebrae, by dual-energy X-ray absorptiometry (DXA). MATERIALS AND METHODS: The study was conducted on 2455 consecutive women attending our Department, from whom 464 normal women were selected. The measurement was validated utilizing a spine phantom. RESULTS: The phantom mean intervertebral disk space was 0.44 cm, with a coefficient of variation of 1.4%. The coefficients of variation in premenopausal, early postmenopausal and elderly women were 2.2, 2.0 and 6.0%, respectively. Values of intervertebral disk space were stable from age 20 to 50 years, thereafter showing a significant (p < 0.05) decrease, negatively correlated with both age and years since menopause (p < 0.0001). In postmenopausal women younger than 60 years, a correlation (p = 0.042) was evident between intervertebral disk space and years since menopause, but no correlation was evident with age. In women over 60 years, no correlations were found between intervertebral disk space and either age or years since menopause. In three groups of age-matched women (47.5 +/- 1.5 years, n = 39 in each group), intervertebral disk space was significantly (p < 0.0001) lower in postmenopausal than in both premenopausal and perimenopausal women. CONCLUSION: The DXA measurement of intervertebral disk space is precise. After menopause, intervertebral disk space shows a progressive decrease that almost entirely occurs in the first 5 - 10 years since menopause, suggesting that the estrogen decrease may rapidly change connective tissue metabolism in the intervertebral disks.

New limit on the neutrinoless betabeta decay of 130Te.

We report the present results of CUORICINO, a search for neutrinoless double-beta (0nu betabeta) decay of 130Te. The detector is an array of 62 TeO2 bolometers with a total active mass of 40.7 kg. The array is cooled by a dilution refrigerator shielded from environmental radioactivity and energetic neutrons, operated at approximately 8 mK in the Gran Sasso Underground Laboratory. No evidence for (0nu betabeta) decay was found and a new lower limit, T(1/2)(0nu) > or = 1.8 x 10(24) yr (90% C.L.) is set, corresponding to [m(nu)] < or = 0.2 to 1.1 eV, depending on the theoretical nuclear matrix elements used in the analysis.

Acute phase markers are associated with reduced plasma lipid levels in a population of hospitalized elderly patients.

BACKGROUND: Several epidemiological studies have documented the presence of a 'J' or 'U' association between total cholesterol levels and total mortality. Not only the mechanism underlying the association between increased mortality and low total cholesterol values is not completely clear, but the relationship itself also appears to be complex in the elderly. OBJECTIVE: The aim of the study was to evaluate the possible association between some biohumoral markers of the acute phase, comorbidity, disability, and reduced levels of some lipoprotein parameters in a sample of hospitalized elderly subjects. METHODS: 341 patients over 65 years of age (185 males, 156 females; mean age 76.2 years), consecutively admitted to our department from 1994 to 1995, were studied. Acute phase was defined as the simultaneous presence of: (1) increased alpha2-plasma protein on electrophoresis (>12%); (2) high fibrinogen concentration (>450 mg/dl), and (3) increased blood sedimentation rate (>15 and >20 mm 1 h in males and females, respectively). RESULTS: The prevalence of signs of acute phase was higher in males and in the youngest patients, but did not change with the level of comorbidity. Patients with signs of acute phase were characterized by lower total, low-density lipoprotein (LDL)- and high-density lipoprotein (HDL)-cholesterol levels compared to subjects without signs of acute phase; this difference was significant even after adjustment for indicators of comorbidity, disability, and nutritional status. Multivariate logistic regression analysis evidenced that the simultaneous presence of these three markers of acute phase was independently associated with low levels of total cholesterol [odds ratio (OR) 2.1, 95% confidence interval (CI) 1.1 - 3.9], and HDL-cholesterol (OR 2.3, 95% CI 1.2 - 4.2), considered as the sex-specific first quintile. CONCLUSION: The findings of this study demonstrate an independent association between acute phase markers and low levels of total and HDL-cholesterol, suggesting that recognized or subclinical diseases in elderly patients may determine a reduction in these plasma lipids. Low level of total and HDL-cholesterol should be considered as possible clinical markers of an underlying state of acute phase rather than a sign of malnutrition. Given the high prevalence of chronic diseases in the elderly, epidemiological studies addressing the lipid profile in this age group should take into account the possible confounding effect of the presence of signs of acute phase.

Alzheimer disease and vascular dementia: relationships with fasting glucose and insulin levels.

Cerebrovascular disease and Alzheimer disease are the leading causes of dementia in elderly subjects. In spite of it, relatively little is known about the pathogenesis and risk factors for dementia. We evaluated fasting plasma glucose and insulin, albumin, lipids, Lp(a) and uric acid levels in nondiabetic patients of both sexes affected by vascular dementia (VD) and senile dementia of the Alzheimer type (SDAT) as well as in a control group of age-matched nondemented subjects. Following a covariance analysis by gender, body mass index, albumin levels and prevalence of arterial hypertension, total and LDL cholesterol as well as HDL cholesterol levels were not significantly different among the three groups. Fasting glucose (p < 0.001 and p < 0.005, respectively) and insulin levels (p < 0.05 for both differences) were higher in patients with VD and SDAT than in control subjects. Our data show that nondiabetic patients with VD or SDAT have higher fasting glucose and insulin levels than healthy control subjects. These metabolic characteristics were not influenced by differences in gender, adiposity, nutritional status, lipids or presence of arterial hypertension.

Acute effects of a single administration of dexamethasone on basal and growth hormone-releasing hormone stimulated GH secretion in acromegaly.

UNLABELLED: A single administration of dexamethasone causes both an early stimulatory and a late inhibitory effect on GH secretion in normal subjects. OBJECTIVE: We investigated the effects of a single administration of dexamethasone on basal and GH-releasing hormone-stimulated GH secretion in eight patients with active acromegaly. DESIGN: On three different days the patients received 4 mg i.v. dexamethasone, 1 microgram/kg body weight GH-releasing hormone 1-29, or matched placebos in different order. PATIENTS: Eight subjects with active acromegaly, five of whom had not been treated previously, while the other three had received octreotide therapy which was stopped at least 7 days before testing. MEASUREMENTS: Serum GH levels were measured in duplicate by a commercially available RIA kit. RESULTS: Dexamethasone administration caused a significant decline of mean +/- SE GH levels from 51.8 +/- 13.8 to 30.0 +/- 9.2 mU/I at 180 minutes, that was not influenced by placebo administration at 180 minutes. On the contrary, when GH-releasing hormone substituted placebo administration, GH levels increased from 34.0 +/- 9.8 mU/I at 180 minutes to 56.0 +/- 15.6 mU/I at 195 minutes. The GH increase was higher when GH-releasing hormone was given without dexamethasone pretreatment (from 52.4 +/- 13.0 mU/I at 180 minutes to 86.4 +/- 25.4 mU/I at 195 minutes). Analysis of the GH area under the curve confirmed the significant inhibition of GH secretion after dexamethasone administration and the significant reduction of the GH response to GH-releasing hormone in the study with dexamethasone pretreatment. CONCLUSIONS: At variance with data in normal subjects, acute i.v. administration of dexamethasone inhibits basal GH secretion and partially suppresses the GH response to GH-releasing hormone in acromegaly. Both alterations in the regulatory mechanism of adenomatous cells and perturbations of hypothalamic regulatory influences, induced by the state of chronic GH hypersecretion, are likely explanations of the different response to dexamethasone.