GHRH-induced GH responses during recombinant GH treatment in patients with short stature.
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Child↗
Biomedical subjects
A Spada
Publications and source records attributed to A Spada.
[Evaluation of the specific delayed cutaneous hypersensitivity response(DTCH) after specific active immunotherapy (SAI) using autologous tumor cells in patients operated upon for renal carcinoma].
From Dec 1986 to Dec 1990, 113 consecutive patients radically resected for renal cell carcinoma, have been randomized after surgery to observation or to Active Specific Immunotherapy (A.S.I.). 43 patients stage I-II and 13 p. stage III, according to TNM entered the treatment arm consisting of 10 autologous irradiated tumor cells injected intradermally, either mixed with BCG 10(7) (on days 28th and 35th after surgery) or alone (on day 42th). At randomization and 1, 6 and 12 months after treatment, patients were evaluated for the development of a DTCH to autologous tumor and to autologous normal cells, obtained by mechanical and enzymatic dissociation of the surgical specimens. Baseline DTCH were negative in all patients. One month after completing A.S.I. 36 out of 50 evaluable patients displayed a significant DTCH response to autologous tumor, which remained positive in 23/40 patients at 6 months. Our data clearly indicate that Active Specific Immunotherapy with autologous tumor cells mixed with BCG can elicit a specific immune response to autochthonous tumor as measured by DTCH.
Adult↗
G-protein oncogenes in acromegaly.
G-proteins belong to a family of proteins which share the common properties of GTP binding and hydrolysis. Heterotrimeric G-proteins are composed of alpha-, beta- and gamma-subunits. The alpha-subunit which differs from one G-protein to another contains the GDP/GTP binding site and has intrinsic GTPase activity. The receptor occupancy causes displacement of bound GDP by GTP, dissociation of free beta gamma-dimer and alpha-GTP complex, interaction of the activated alpha-GTP complex with intracellular effectors, such as enzymes and ion channels. The turn off of the reaction is due to the GTPase activity which causes the hydrolysis of GTP to GDP. G-proteins are essential for transferring hormonal signals from cell surface receptors to intracellular effectors. Since G-proteins generate intracellular effectors involved in cell growth, G-protein genes have the propensity to be converted into oncogenes. In fact, mutations in the alpha-subunit of Gs (the G-protein involved in the activation of adenylyl cyclase) have been demonstrated in 40% of human GH secreting pituitary adenomas. Single amino acid substitutions replacing Arg 201 with either Cys or His or Gln 227 with either Arg or Leu cause constitutive activation of adenylyl cyclase by inhibiting GTPase (gsp oncogene). The same mutations were identified in about 10% of thyroid adenomas and in the McCune-Albright syndrome.
Acromegaly↗
Mutations in the alpha subunit of the stimulatory regulatory protein of adenylyl cyclase (Gs) in human GH-secreting pituitary adenomas. Biochemical, clinical, and morphological aspects.
Very recently a subset of human GH-secreting pituitary adenomas carrying a somatic mutation in the alpha subunit of the stimulatory regulatory protein of adenylyl cyclase (Gs) was identified. In all these tumors (Group 2; about 30% of all the GH secreting tumors studied) the alpha s cDNAs contained mutations; in 8 tumors mutations replaced Arginine 201 with either Cystein or Histidine while in the remaining tumors Glutamine 227 was replaced by either Arginine or Leucine. No mutations were observed in the remaining adenomas (Group 1). The two mutations caused a constitutive activation of adenylyl cyclase and a turn on of cAMP synthesis by inhibiting GTPase activity. The transformed phenotype was reflected in adenomatous cells with high rate of cAMP production and in vitro GH secretion. No difference in age, sex, clinical features, duration of the disease and cure rate were observed between the patients without (Group 1) or with alpha s mutation (Group 2), while higher serum GH levels and smaller tumor size were present in Group 2 patients. Moreover, hypersecretory activity in Group 2 tumors was also apparent at electron microscopy; cells of Group 2 tumors were densely granulated and showed prominent rough endoplasmic reticulum and Golgi complex. With respect to Group 1, Group 2 patients were less responsive to GH-releasing hormone (GHRH), while they were more sensitive to somastostatin. The former finding is in agreement with the hypothesis that the oncogenic proteins mimic the effects of extracellular growth factors, so removing the requirement for GHRH; the latter might explain the low rate of tumor growth as due to the counteracting role of endogenous inhibitory factors.
Adenoma↗
Natural killer (NK) and lymphokine activated killer (LAK) cell activity in patients (PTS) treated with flavone acetic acid (FAA).
Natural killer (NK) cell activity was measured in nine patients with different solid tumors treated with flavone acetic acid (FAA). In three of them, NK cell activity was significantly increased, in two instances even after repeated courses of treatment. A significant increase in lymphokine activated killer (LAK) cell activity was also observed in three of four patients after in vivo treatment with FAA and in vitro incubation of lymphocytes with recombinant Interleukin-2. We observed some inter-individual variability in drug clearance, but no apparent correlation between drug plasma levels (neither peak nor AUC values) and the effects on NK and LAK activity.
Adjuvants, Immunologic↗
Effects of consecutive doses of GHRH on GH secretion.
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Adult↗
In vivo detection of somatostatin receptors in patients with functionless pituitary adenomas by means of a radioiodinated analog of somatostatin ([123I]SDZ 204-090).
The recent availability of a Tyr3-substituted octreotide (SDZ 204-090) for radioiodination has allowed somatostatin (SRIH) receptor binding to be studied in vivo, and receptor-positive tumors of different origins to be visualized with a gamma-camera. This prompted us to investigate whether this compound could be used for external imaging of functionless pituitary adenomas displaying SRIH receptors. Eight patients with functionless pituitary adenomas, three patients with acromegaly, and three with macroprolactinoma were injected iv with 123I-labeled Tyr3-octreotide and then scanned with a gamma-camera. Positive scans were obtained in the three acromegalics and in two of the eight patients with functionless pituitary tumors. The patients with macroprolactinoma had negative scans. The diagnosis of functionless pituitary adenomas was confirmed by light and electron microscopic examination as well as immunocytochemical studies. In vitro binding of [125I]Tyr11-SRIH to cell membranes was evaluated in four functionless and three GH-secreting adenomas removed from seven of the patients. All of the GH-secreting as well as one of the four functionless adenomas had high affinity SRIH-binding sites, without differences in number or affinity, whereas SRIH-binding sites were not detected in the others. Positive scans were observed only in patients bearing tumors with high affinity SRIH-binding sites. In conclusion, [123I]Tyr3-octreotide appears to be a promising tool for singling out, in vivo, patients with functionless pituitary tumors displaying SRIH receptors who might potentially benefit from octreotide treatment.
Adenoma↗
Hypothalamic peptides modulate cytosolic free Ca2+ levels and adenylyl cyclase activity in human nonfunctioning pituitary adenomas.
The effects of hypothalamic peptides (TRH, GnRH, arginine vasopressin, vasoactive intestinal peptide, GHRH, CRH, and SRIH) on cytosolic free calcium concentrations ([Ca2+]i) and adenylyl cyclase (AC) activity were evaluated in 12 nonfunctioning pituitary adenomas. TRH, GnRH, and arginine vasopressin induced a marked [Ca2+]i rise in 10/12, 4/12, and 2/5 tumors, respectively. The transients induced by these peptides were due to both Ca2+ mobilization from the intracellular stores and Ca2+ influx from the extracellular medium. AC activity was evaluated in 10 adenomas; 1 microM vasoactive intestinal peptide induced a 2- to 6-fold stimulation of the enzyme activity in all tumors, while neither GHRH nor CRH were effective. Moreover, in 5/10 tumors 1 microM SRIH reduced both AC activity and [Ca2+]i, while in 2/10 the peptide caused a significant rise in [Ca2+]i despite the AC inhibition and in 3/10 SRIH did not modify either AC activity or [Ca2+]i. This study indicates that in nonfunctioning pituitary adenomas a wide spectrum of hypothalamic peptides modulate [Ca2+]i and AC activity. Moreover, the presence of biologically active receptors may offer a possible target for therapeutic intervention.
Adenoma↗
Effect of two consecutive administrations of GHRH in children with constitutional growth delay.
It has been suggested that children with constitutional growth delay might have a transient immaturity of the neurotransmitter pathways necessary for the control of growth hormone releasing hormone (GHRH) secretion. In this study we evaluated the effects of two consecutive GHRH boluses (1 microgram/kg, i.v.) in nine prepubertal boys with constitutional growth delay. Growth hormone (GH) responses to GHRH administration were similar to that observed in normal children (first GHRH bolus, GH net incremental area under the curve (nAUC) +/- SE: 788 +/- 244 vs 984 +/- 242 ng/ml per hour; second bolus, GHnAUC: 657 +/- 122 vs 541 +/- 129 ng/ml per hour, respectively). These data suggest that no relevant abnormalities in the mechanisms determining the somatotroph sensitivity to GHRH are present in children with constitutional growth delay.
Adolescent↗
TRH raises cytosolic Ca2+ in human adenomatous lactotrophs.
The effect of TRH on cytosolic free calcium concentrations, [Ca2+]i, was evaluated on cell suspensions obtained from 6 human PRL secreting pituitary adenomas. In these cells resting [Ca2+]i levels were variable (mean +/- SE; 103.8 +/- 6.5, n = 25); the addition of 100 nM TRH caused a marked [Ca2+]i rise within 20 sec., the peak values ranging from 200 to 437 nM (285 +/- 10.8 nM, n = 10). The transients induced by TRH were composed by a rapid increase, due to mobilization of calcium from intracellular stores, followed within a few seconds by a lower plateau which was due to stimulated influx from the extracellular space. In fact, when EGTA and verapamil were applied after TRH they caused the Ca2+ plateau to dissipate rapidly. The addition of 1 microM dopamine (DA) caused a substantial decrease of resting [Ca2+]i (about 10-30%) as well as an inhibition of the plateau phase induced by TRH. The effect of DA completely depended on extracellular Ca2+. The TRH-induced transients observed in adenomatous cells were quite similar in size and time course to those recorded in normal rat lactotrophs. As previously observed in rat lactotrophs, in adenomatous cells treatment with pertussis toxin (PTx, 1 microgram/ml for 4 h) was unable to affect the [Ca2+]i transients induced by TRH while completely abolished the effect of DA. The effects of TRH on in vivo and in vitro PRL secretion were also evaluated. Before surgery, no patient showed a positive response to the iv administration of 200 micrograms TRH (serum PRL levels: 95 +/- 62 ng/ml in basal conditions vs 124 +/- 92 after TRH, P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Repetitive injections of GHRH in normal children and adults.
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Adult↗
Inhibition of basal and corticotropin-releasing hormone-stimulated adenylate cyclase activity and cytosolic Ca2+ levels by somatostatin in human corticotropin-secreting pituitary adenomas.
The effects of CRH and somatostatin (SRIH) on adenylate cyclase (AC) activity, intracellular free calcium concentrations [( Ca2+]i) and in vitro ACTH release were investigated in six human ACTH-secreting pituitary adenomas. In all tumors, CRH induced a marked stimulation (from 69-210% at 10 nM), whereas SRIH caused a definite inhibition (from 29-50% at 100 nM) of membrane AC. When added together, CRH and SRIH caused a purely additive effect on AC. In adenomatous corticotrophs CRH (10 nM) caused [Ca2+]i to rise from 160 +/- 30 nM (mean +/- SD) to 410 +/- 95 nM. CRH-induced transients were biphasic, with an initial peak predominantly due to redistribution from intracellular Ca2+ stores and a secondary phase due to Ca2+ influx. The effects of CRH on [Ca2+]i were totally independent of the stimulation of AC. In fact, cAMP-elevating agents other than CRH did not modify [Ca2+]i. SRIH (100 nM) decreased resting [Ca2+]i (approximately 20-40%) as well as [Ca2+]i rises induced by CRH, arginine vasopressin, or high K+. The effect of SRIH on [Ca2+]i was maintained in presence of high cAMP levels, while was totally abolished after pertussis toxin pretreatment. CRH (10 nM) stimulated ACTH release (from 22.5 +/- 3.5 to 45.0 +/- 8.5 pmol/L) by an extent similar to that elicited by calcium ionophore and forskolin. By contrast, SRIH (0.1 microM) inhibited both basal and CRH-stimulated ACTH release. In conclusion, in human adenomatous corticotrophs SRIH exerts an inhibitory action by reducing both AC activity and, independently, [Ca2+]i. In this way, SRIH can efficiently counteract the stimulatory action of CRH that in these cells involves activation of both cAMP and Ca2+ pathways.
Adenoma↗
Clinical, biochemical, and morphological correlates in patients bearing growth hormone-secreting pituitary tumors with or without constitutively active adenylyl cyclase.
Somatic mutations in the alpha-chain (alpha s) of the stimulatory regulatory protein of adenylyl cyclase (Gs) causing constitutive activation of the enzyme have been identified in a subset of human GH-secreting pituitary adenomas. This study reports on the differences between acromegalic patients bearing tumors without (group 1; n = 51) or with (group 2; n = 29) this alteration. No difference in age, sex, clinical features, duration of the disease, or cure rate was observed between the two groups. By contrast, group 2 patients had higher basal GH levels than group 1. Moreover, a significant difference in sellar morphology was found; group 2 patients more frequently showed sellas of normal size (grade I) than group 1. Hypersecretory activity of group 2 tumors was also apparent at electron microscopy; contrary to those of group 1, cells of group 2 tumors were densely granulated and showed prominent rough endoplasmic reticulum and Golgi complex. With respect to group 1, group 2 patients were less responsive to GH-releasing hormone, while they were more sensitive to somatostatin- and dopamine-induced GH inhibition. These results suggest that patients with constitutively active adenylyl cyclase have hyperactive tumors; the sensitivity of these tumors to inhibitory agents (somatostatin and dopamine), possibly counteracting the expression of activating mutations, might explain the low rate of tumor growth.
Acromegaly↗
GTPase inhibiting mutations activate the alpha chain of Gs and stimulate adenylyl cyclase in human pituitary tumours.
A subset of growth hormone-secreting human pituitary tumours carries somatic mutations that inhibit GTPase activity of a G protein alpha chain, alpha(s). The resulting activation of adenylyl cyclase bypasses the cells' normal requirement for trophic hormone. Amino acids substituted in the putative gsp oncogene identify a domain of G protein alpha-chains required for intrinsic ability to hydrolyse GTP. This domain may serve as a built-in counter-part of the separate GTPase-activating proteins required for GTP hydrolysis by small GTP-binding proteins such as p21ras.
Adenylyl Cyclases↗
Somatomammotrophic cells in GH-secreting and PRL-secreting human pituitary adenomas.
A morphological study has been carried out on 20 GH-secreting adenomas removed from acromegalic normoprolactinemic patients, on 29 PRL-secreting adenomas removed from hyperprolactinemic patients without signs of acromegaly and on one normal human anterior pituitary gland collected at autopsy. The protein A-gold immunoelectron microscopic technique has been utilized in order to verify the presence of mixed cells producing both GH and PRL (somatomammotrophs) in these pituitary tissues. In the normal pituitary a considerable number of somatomammotrophs (15-20%) was found, thus supporting the idea that these cells are normal components of the human anterior pituitary gland. In 10 GH-secreting adenomas and in 10 PRL-secreting adenomas somatomammotrophs were present in a variable number (from 4 to 20% of the whole cell population in GH adenomas and from 1 to 47% in PRL tumors). It can be concluded therefore that these cells, largely present in all GH/PRL-secreting adenomas, can also be found in GH-secreting and PRL-secreting tumors without clinical evidence of a mixed secretion. Adenomatous somatomammotrophs displayed ultrastructural features of adenomatous somatotrophs and mammotrophs (prominent Golgi complexes, abundant rough endoplasmic reticulum, irregular nuclei). The size and the number of granules were variable. In some cells GH and PRL were stored in distinct secretory granules, in others in mixed granules or both in mixed and distinct granules, thus suggesting that in adenomatous somatomammotrophs the efficiency of the mechanisms of sorting of the two hormones varies from one cell to another.(ABSTRACT TRUNCATED AT 250 WORDS)
Acromegaly↗
Different GH responsiveness to repeated GHRH administration in normal children and adults.
It has been previously reported that repeated GHRH administration leads to a reduction in growth hormone responses in adults. In order to verify if this regulatory mechanism is also operating in children, we compared GH secretory responses to repeated GHRH in normal children and adults. The administration of the first GHRH bolus caused a marked GH rise (expressed as net incremental area under the curve, nAUC +/- SE) both in children (GH nAUC: 1184 +/- 216 ng/ml/h) and in adults (GH nAUC: 701.2 +/- 90 ng/ml/h). The second GHRH bolus induced a different pattern of GH secretion in the two groups. In children the peptide determined a clear GH rise (GH nAUC: 518 +/- 147 ng/ml/h), while in adults the second GHRH injection was uneffective (GH nAUC: 21 +/- 20 ng/ml/h). These preliminary results indicate that in children repeated GHRH administration does not induce refractoriness to GHRH action, suggesting different regulatory mechanism of GH secretion in normal children and adults.
Adolescent↗
Alpha 1-adrenergic stimulation of in vitro growth hormone release and cytosolic free Ca2+ in rat somatotrophs.
The effects of alpha 1-adrenergic agents on GH release and intracellular free Ca2+ concentration ([Ca2+]i) were investigated in purified rat somatotroph preparations. Phenylephrine (PHE) stimulated in vitro GH release; the maximal effect (2.5-fold stimulation) occurred at 1 microM PHE. The effect was completely blocked by the alpha-adrenergic antagonist phentolamine and partially counteracted by the beta-antagonist propranolol. Experiments with the fluorescent Ca2+ probe fura 2 show that PHE causes [Ca2+]i to rise from 178 +/- 31 nM (mean +/- SE; n = 25) to 370 +/- 55 nM (n = 9). This effect was complete within 20 sec and was maintained for at least 5-10 min. The rise was rapidly interrupted by administration of 1 microM phentolamine. The beta-receptor agonist isoproterenol caused a small [Ca2+]i rise due to action on alpha 1-adrenoreceptors. The PHE-induced [Ca2+]i rise showed two components: an initial peak due to Ca2+ mobilization from intracellular stores and a subsequent rise due to Ca2+ influx from the extracellular space. Somatostatin (SRIF) lowered both resting [Ca2+]i and Ca2+ influx stimulated by PHE. Pertussis toxin pretreatment did not modify PHE-induced [Ca2+]i changes, while it completely prevented the effect of SRIF on both resting and triggered [Ca2+]i, thus suggesting that a GTP-binding protein sensitive to the toxin is involved in the transduction of SRIF action. The increase in cAMP induced by cholera toxin pretreatment modified neither PHE nor SRIF action on [Ca2+]i. In conclusion, in rat somatotrophs Ca2+ mobilization and influx are stimulated by alpha 1-adrenergic agents, and this triggered [Ca2+]i rise results in a stimulation of GH release. In these cells SRIF is able to reduce both resting [Ca2+]i levels and [Ca2+]i increases induced by alpha 1-adrenergic activation.
Adenosine Diphosphate Ribose↗
Growth hormone and prolactin secretion in acromegaly: correlations between hormonal dynamics and immunocytochemical findings.
A morphological study was carried out on pituitary adenomas removed from 13 normoprolactinemic and 9 hyperprolactinemic acromegalic patients whose hormonal dynamics had been carefully investigated. Double immunocytochemical labeling with the protein-A-gold electron microscopic technique was used to detect the presence of GH and PRL in the adenomas. Two morphological patterns were found; 11 adenomas contained cells positive only for GH, and 11 contained a variable proportion (from 10-98%) of cells positive for PRL. The great majority of cells positive for PRL also were positive for GH and so were actually mammosomatotrophic cells. Among the normoprolactinemic patients, no cells containing PRL were found in the tumors from 8 patients, and 10-26% of the cells of the tumors of the other 5 patients contained PRL. Two thirds of the hyperprolactinemic patients had tumors containing mammosomatotrophs (18-80%) with or without the concomitant presence of mammotrophs (0-18%). A positive correlation was found between the serum PRL levels and the percentage of mammosomatotrophs. No significant differences in GH secretory responses to TRH, dopamine, GHRH, and SRIH were found between patients having tumors with or without cells positive for PRL. We conclude that 1) the frequency of mammosomatotrophs in adenomas from acromegalic patients is higher than that previously estimated using different immunocytochemical methods; and 2) serum GH responses to TRH and dopamine are not strictly related to the presence of mammosomatotrophs and/or mammotrophs within the tumor.
Acromegaly↗