Biomedical subjects

M Giusti

Publications and source records attributed to M Giusti.

At least 73 records · Page 4Linked to original sources

PubMed1997

Immunoreactive endothelin in nodular pathology of the thyroid.

OBJECTIVES: Endothelins (ETs) can act as autocrine and/or paracrine regulators of thyroid homeostasis and growth. The aim of this study was to evaluate immunoreactive ET (i-ET) levels in a group of patients with nodular pathology of the thyroid and to correlate them with the cytomorphological features after fine-needle aspiration (FNA) and with hormonal and immunological status and blood pressure levels. DESIGN: Plasma and cystic i-ET were assayed in a group of patients with varying thyroid function, who underwent FNA for solid and cystic nodular pathology. PATIENTS: 47 patients (32-81 years) with nodular pathology of the thyroid and 18 controls (28-70 years) with normal thyroid function and morphology were studied. MEASUREMENTS: Fasting venous blood samples were collected and the plasma for i-ET was frozen at -80 degrees C until assayed. Sera were frozen at -20 degrees C for FT3, FT4, TSH, TPO autoantibodies and thyroglobulin autoantibodies assay. Cystic fluid was obtained by FNA, centrifuged, and the supernatant was stored at -20 degrees C until i-ET assay. FNA cytology was examined by light microscopy. RESULTS: In patients with cystic nodules, plasma i-ET levels were significantly (P = 0.002) higher (5.7 +/- 1.1 ng/l, +/- SEM) than in both patients with solid nodules (2.6 +/- 0.4 ng/l) and (P = 0.02) controls (3.0 +/- 0.3 ng/l). In patients with cystic nodules, cystic i-ET levels (12.6 +/- 1.9 ng/l) were significantly (P = 0.003) higher than plasma levels (5.7 +/- 1.1 ng/l) and did not correlate with the percentage of FNA cellularity. i-ET levels in cystic fluid (12.6 +/- 1.9 ng/l) were significantly (P = 0.0001) higher than plasma i-ET levels in both patients with solid nodules and controls. No difference in either plasma or cystic i-ET levels was found in patients with cystic nodules in relation to differences in thyroid function. No difference in plasma i-ET levels was found between patients with solid nodules and controls. In controls, no significant difference in plasma i-ET levels was found between males and females. A negative correlation (r = -0.55, P = 0.02) was found between cystic i-ET levels and systolic and diastolic blood pressure. No correlation between cystic or plasma i-ET levels and FT3, FT4 or TSH was found in any of the subjects studied. CONCLUSIONS: It seems that endothelins do not possess a primary role in determining thyroid function and that the increased levels in cystic fluid found in our subjects could be secondary to cystic nodule development.

Adult↗

PubMed1997

Clinical results of long-term slow-release lanreotide treatment of acromegaly.

Medical therapy is frequently needed to normalize growth hormone/insulin-like growth factor I secretion in acromegaly. The aim of this study was to determine the long-term effects of the slow-release (SR) somatostatin analogue lanreotide in 57 acromegalic patients. SR lanreotide (30 mg) was given every 14 days for 12 months. In 33% of patients, the drug dosage was raised to 60 mg and/or the time interval was shortened to 10 days. Two months of clinical evaluation followed drug discontinuation in 47 out of 48 (84%) patients who completed the 12-month period. A drug-related decrease in GH/IGF-I levels was observed. Basal GH/IGF-I levels were significantly (P < 0.001) reduced at 12 months, IGF-I was normalized in 35% of patients and GH levels were < 5 micrograms L-1 in 54%. There was a clinical improvement in patients complaining of joint pain, rachialgias, headache, digital paraesthesias and hyperhidrosis. Soft-tissue changes were documented by significant (P < 0.001) decreases in finger size. In 52 (91%) patients without overt diabetes, a slight but significant increase in integrated glycaemia (P < 0.001) was noted, while integrated insulin levels were reduced (P < 0.001). Of 33 (58%) patients with normal basal ultrasound examination of the gall bladder, three (9%) had developed asymptomatic gall stones or biliary sludge after 12 months. Adverse events were generally mild. They frequently (52%) occurred after the first SR lanreotide administration; only 28% were recurrent and 20% appeared for the first time during therapy. SR lanreotide is an effective treatment in most unselected acromegalic patients. Tolerance towards the drug is high. Subjective benefits seem to override the simple biochemical control of the disease. Glucose homeostasis more than the incidence of gall stones seems to require monitoring on therapy. SR lanreotide is clearly advantageous in improving patient compliance with medical treatment for acromegaly.

Acromegaly↗

PubMed1997

Decreased steroidogenesis and cAMP production in vitro by leydig cells isolated from rats made hypothyroid during adulthood.

UNLABELLED: The Leydig cell function of adult male rats made hypothyroid with 6-propyl-2-thiouracil (6-PT, 0.1% w/v in drinking water for 1 month) was studied and compared with that of age-matched controls. After 6-PT treatment, a slight, non-significant decrease in serum testosterone was observed, but no changes in testis weight or number of Leydig cells were noted. The in vitro function of Leydig cells was therefore investigated during incubation for 3 h in the presence or absence of several stimuli: LH (30 mIU/mL), forskolin (FK 1 microM), isobutylmethylxanthine (IBMX, 100 microM), GnRH (100 nM) or FK 1 microM + IBMX 100 microM. Irrespective of the stimulus, cells from hypothyroid rats secreted less cyclic AMP, 17-hydroxyprogesterone, androstenedione and testosterone. No differences in LH receptors were noted between the groups. Prolonged incubation with triiodothyronine (5-250 ng/mL) or thyroxine (5-250 ng/mL) for 3, 16, 24 or 48 h did not affect testosterone secretion in either group; however, administration of IGF-I (8 ng/mL for 24 h) resulted in increased spontaneous and stimulated testosterone production in both groups. However, when hypothyroid animals were supplemented in vivo with thyroxine a full recovery of Leydig cell function in vitro was noted. IN CONCLUSION: (1) Leydig cells from rats made hypothyroid during adulthood produce less testosterone in vitro, both spontaneously and in response to cAMP and non-cAMP-mediated stimuli; (2) this is due to a reduction in cAMP production and in the activity of the enzymes in the androgen biosynthetic pathway, and not to changes in LH receptors; (3) direct administration of thyroid hormones did not improve testosterone secretion in either group, while incubation with IGF-I did.

Animals↗

PubMed1997

Testosterone metabolism and cyclosporin A treatment in rheumatoid arthritis.

A constant dose-dependent side-effect in cyclosporin A (CSA)-treated patients is the appearance of hypertrichosis; this occurs in both sexes and suggests an androgenizing activity. To determine the influence of CSA on peripheral androgen metabolism, we evaluated in rheumatoid arthritis (RA) patients treated with low-dose CSA (3.5 mg/kg/day), during a period of 12 months, plasma levels of testosterone (Tes) and of 5alpha-androstane-3alpha, 17beta-diol glucuronide (Adiol-G), an important peripheral Tes metabolite. Clinical and laboratory parameters of RA were also monitored. Furthermore, the metabolism of physiological concentrations of Tes (1 x 10(-8) M) was evaluated in primary cultures of RA synovial macrophages (M phi) in the presence of CSA concentrations close to the pharmacological immunosuppressive doses (100-500 ng/ml). At the final time of observation (12 months), a significant increase in the mean plasma Adiol-G level was observed in patients of both sexes. The increase was evident after 1 month of treatment in male patients (P < 0.01) and after 3 months in female patients (P < 0.05). Almost all the patients experienced the side-effect of a low-degree hypertrichosis after a mean period of 1-2 months. No significant correlations with the laboratory parameters of the disease were observed. Results from in vitro experiments on Tes metabolism by cultured synovial M phi showed at 24 and 48 h, in the presence of CSA, a significantly (P < 0.0001) greater formation of dihydrotestosterone and increased amounts of other Tes metabolites, including androstenedione, androsterone and epiandrosterone, when compared to untreated controls. In conclusion, the appearance of a dose-related hypertrichosis and the increase in plasma androgen metabolites (i.e. Adiol-G) in CSA-treated patients, as well as the hormonal metabolic effects on cultured synovial M phi, should be regarded as possible markers of the influence of CSA on peripheral androgen metabolism at the level of target cells.

Adult↗

PubMed1997

Nitric oxide modulates in vivo and in vitro growth hormone release in acromegaly.

Nitric oxide (NO) has recently been shown to modulate pituitary secretion both in vivo and in vitro. The aim of this study was to investigate the effects of this chemical transmitter on spontaneous and growth-hormone-releasing hormone (GHRH)-induced growth hormone (GH) secretion in acromegalic patients, as well as from GH-secreting tumors maintained in vitro. The study was carried out in 7 acromegalic patients (46.2 +/- 2 years) and in 5 normal subjects (40.1 +/- 1.5 years). GH and prolactin (PRL) secretion were assayed during the administration of isosorbide dinitrate (ID, 5 mg, orally), an NO donor, GHRH, and ID plus GHRH. During ID, a significant (p < 0.05) increase (37%) over basal GH levels was only observed in acromegalics. There was no change in GH levels in response to GHRH or ID plus GHRH in either group. No significant change in PRL levels was observed in either group during ID, while GHRH, with or without ID, induced a slight increase in PRL levels in acromegalics only. Tumor specimens were obtained by selective transsphenoidal adenomectomy, and the cells were plated and incubated for 1, 2 and 24 h in the presence of sodium nitroprusside, a releaser of NO (SNP, 0.3 or 0.6 mM), of GHRH (10-8 M) or of both. SNP significantly (p < 0.001) increased GH levels in a dose-dependent manner (R = 0.99, p = 0.02), but was unable to modify the GH response to GHRH. In acromegalics, a significant correlation (R = 0.822, p < 0.045) and a correlation near the limit of significance (R = 0.73, NS) were observed respectively between the in vivo GH response to ID and the in vitro response to SNP at 24 h. No significant effect was observed on PRL secretion during SNP incubations, while GHRH produced a significant increase in PRL after 2 and 24 h incubation in acromegalics. These observations indicate that NO plays a stimulatory role in vivo and in vitro on GH secretion in acromegalic patients.

Acromegaly↗

PubMed1997

Melatonin receptors are present in adult rat Leydig cells and are coupled through a pertussis toxin-sensitive G-protein.

Previous studies have suggested that melatonin (MLT) acts directly on rat Leydig cells by modulating androgen production. In the present study, the site of action of MLT was investigated. The binding of 2-[125I]iodomelatonin (125I-MLT; 7-240 pmol/l) to Leydig cell membrane fragments was tested in the presence or absence of guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S; 50 mumol/l). Saturation studies and Scatchard analysis revealed the existence of a high-affinity binding site with a Bmax of 46.70 +/- 3.50 fmol/mg protein and a Kd of 88.70 +/- 6.20 pmol/l; treatment with GTP-gamma-S reduced the concentration of 125I-MLT binding sites (Bmax 34.03 +/- 4.50), while increasing the Kd to 106.5 +/- 2.61 pmol/l. Pretreatment of the cells with pertussis toxin (PTX; 10 ng/ml for 16 h) resulted in a decreased binding of 125I-MLT and a lack of effect of GTP-gamma-S. Moreover, the effect of MLT on testosterone secretion induced by LH (30 mIU/ml), forskolin (1 mumol/l) and LHRH (100 nmol/l) was studied after 3-h incubation of cells which had been precultured with or without PTX. The inhibition of testosterone secretion due to MLT administration was eliminated by PTX pretreatment during forskolin and LH, but not during LHRH administration. However, 17-hydroxyprogesterone levels were higher in all groups incubated in the presence of MLT, irrespective of PTX pretreatment. Our data suggest that: (a) MLT receptors are present on the membranes of adult rat Leydig cells; (b) they couple through PTX-sensitive G-protein-coupled binding sites; (c) the mechanism by which MLT blocks 17-20 desmolase enzymatic activity (thus leading to increased 17-hydroxyprogesterone levels), and testosterone secretion during LHRH stimulation is likely to depend on one or more different mechanism(s) of action.

Animals↗

PubMed1997

Effects of sumatriptan on growth hormone releasing hormone-stimulated growth hormone secretion in acromegaly.

Sumatriptan (SU), a specific 5-HT1D receptor agonist, was recently shown to be able to increase growth hormone (GH) levels in normals, but not in acromegalics, while no effect was seen on prolactine (PRL). SU is also able to produce an increase in GH response to growth hormone releasing hormone (GHRH) in prepubertal children. In this study we investigated whether SU administration influences GHRH-induced GH secretion in 8 acromegalics, and 6 age-matched normal volunteers, as a control group. We evaluated the effects of SU (6 mg s.c.) or placebo (PL) administration on GHRH (1 microgram/kg bw i.v.)-induced GH and PRL secretion. After SU priming the GH response to GHRH did not changed in acromegalics, but significantly decreased in controls, in comparison with that observed after PL plus GHRH. In acromegalics, no difference in GH peak was seen after SU plus GHRH and PL plus GHRH, nor was any difference seen in AUC between tests. In controls, no difference was seen in GH peaks, while SU priming significantly (P < 0.03) decreased the AUC 90-120 min of GH after GHRH administration. In acromegalics, SU did not change the slight GHRH-induced increase in PRL levels. Our study documents that 5-HT1 D receptors do not interfere with GHRH-stimulated GH secretion in acromegalic subjects. In normals, SU is able to decrease GH response to GHRH, thus confirming that 5-HT1D receptors are able to modulate GH secretion in normals.

Acromegaly↗

PubMed1996

Sleep in patients with chronic primary insomnia during long-term zolpidem administration and after its withdrawal.

A double-blind trial was carried out to determine the effect of zolpidem or a placebo on sleep in two groups of insomniac patients with a diagnosis of moderate chronic primary insomnia. Zolpidem was given at a daily dose of 10 mg for 27 nights and was preceded (two nights) and followed (three nights) by a placebo. Zolpidem induced a significant increase of total sleep time, while total wake time and wake time after sleep onset were reduced. Values corresponding to stage 2 sleep were augmented, while stage 3 sleep and REM sleep showed no significant changes. Tolerance did not develop during the zolpidem administration period, and rebound insomnia did not show following abrupt interruption of drug administration. In addition, patients on zolpidem had a more peaceful sleep with no decrement of levels of alertness.

Adult↗

PubMed1996

Effectiveness and tolerability of slow release lanreotide treatment in active acromegaly: six-month report on an Italian multicenter study. Italian Multicenter Slow Release Lanreotide Study Group.

The objective of the study was to determine the tolerability and effectiveness of the slow release (SR) somatostatin analog lanreotide in active acromegaly. Fifty-seven patients, unselected in terms of their previous responsiveness to octreotide therapy, were included in a prospective, open label study carried out at 6 Italian endocrinological centers. The effects of 6 months of SR lanreotide, given at first every 14 days at a dosage of 30 mg, im, were recorded. In some patients (33%), drug dosage was adjusted by increasing the dose (to 60 mg, im) and/or shortening the time interval (every 10 days) of SR lanreotide administration. Fifty patients completed the 6-month period of therapy; 2 subjects dropped out because of adverse events, and 5 dropped out because of ineffectiveness after changes in drug administration. The first SR lanreotide injection produced more than 50% suppression of GH levels from the basal value in 93% of patients. Thirteen days later, baseline GH levels were reduced by over 50% in 25% of patients. Mean GH values were normalized in 85% of patients after 6 months, whereas insulin-like growth factor I (IGF-I) levels were normalized in 38% of patients. No correlation was found between pretreatment GH levels and GH response to SR lanreotide or between changes in GH and IGF-I during therapy. During treatment, there was a significant reduction in the percentage of patients complaining of joint pain, hyperhydrosis, and paresthesias. Changes in soft tissue swelling were documented by significant decreases in finger measurements. Diarrhea and abdominal pain were the most frequent side-effects when therapy was started; these progressively decreased. After the first month of therapy, moderate, mild, and no side-effects were reported by 3%, 40%, and 53% of patients. A nonsignificant increase occurred in asymptomatic gallstones and amylase levels. Minimal changes were noted in carbohydrate tolerance, consisting of a slight increase in glycosylated hemoglobin, a rise in glucose and a decrease in pre- and postprandial insulin levels. No effects on PRL, free cortisol, TSH, or free thyroid hormone levels were noted. No significant change in the percentage of visual field abnormalities was noted. Decreases in pituitary tumor size occurred in 3 of 17 patients reevaluated after 6 months of therapy. The 6-month period of SR lanreotide therapy was compared, on an anamnestic basis, with a 6-month or longer period of sc octreotide therapy (median, 300 micrograms/day) in 34 patients. There were no differences in effectiveness or tolerability between the 2 somatostatin analogs. These data indicate that SR lanreotide at a dose of 30 mg, im, every 14 days is an effective treatment in most unselected acromegalic patients. When administered to a group of poorly responsive patients, an increase in drug dose (60 mg im) and/or a shortening of the drug interval (10 days) seem to improve the GH/IGF-I response. Tolerability to SR lanreotide therapy is high. The use of a new sustained release formulation of somatostatin analog is clearly advantageous in improving patient compliance with medical treatment for acromegaly.

Acromegaly↗

PubMed1996

Enzyme polymorphism on the metabolic O-demethylation of dextromethorphan in a South American population.

The polymorphic oxidative metabolism of debrisoquine and sparteine were discovered in the seventies by Mahgoub and Eichelbaum. Since then, many other therapeutic substances were added and one of these drugs is dextromethorphan. The object of this investigation was to ascertain the distribution of the oxidative phenotype of dextromethorphan in the Uruguayan population. The drug and its metabolite, dextrorphan, were quantified in the urine of 165 healthy volunteers by modification of an HPLC method by Chen et al. The metabolic ration was calculated and frequency distribution histograms were drawn. By inspection of the histogram two antimodes can be assigned which determine three sub-populations: on one side the fast extensive metabolizers (n = 30, 18.2%), in the middle the extensive metabolizers (n = 123, 74.5%) and on the other extreme of the histogram the slow metabolizers (n = 12, 7.3%). No other studies have confirmed thus far this trimodal distribution. This research will be continued by genotyping the populations studied in order to confirm these findings and to elucidate the underlying genetic mechanisms of the polymorphism.

Adult↗

PubMed1996

[Sudden and unusual onset of penile plastic induration in 2 patients neurosurgically treated for pituitary macroadenoma].

Induratio penis plastica (IPP) or Peyronie disease is characterized by the developing of fibrotic plaques in the tunica albuginea of penis, that in the latter stages can lead to impotence. The etiology of this disease is still unknown even if various factors such as inflammation, autoimmunity or traumas are involved. Usually it occurs after 40 years of age, even if cases in young patients have been described. The onset of IPP can be acute in about 50% of the patients, while in the others it is characterized by a chronic but progressive progress. In this work, we describe the cases of two patients 52 and 66 years old, who arrived to our department for a decrease of libido and sexual potency in the last months. The patients were not smokers and took no drugs and they had never complain symptoms and signs of IPP. In both subjects an endocrine pattern compatible with partial hypopituitarism was present and in the first patient it was associated with an ACTH-dependent hypercortisolism. Pituitary imaging with MRI showed in both patients the presence of a mass compatible with macroadenoma, that in the first patient showed characteristic of invasiveness. Both subjects underwent transphenoidal neurosurgery with the exeresis of the neoplasia, with resolution of the secondary hypogonadism and reappearance of the sexual potency. With the resume of sexual activity the patients complained the appearance of painful penis bending during erection. Dynamic echographic evaluation of the penis with 7.5 Mhz linear probe, after the intracavernous injection of prostaglandin E1 10 micrograms, showed in both patients the presence of a hyperechogenic plaque in the tunica albuginea compatible with IPP. Both patients underwent successfully surgery for the excision of the plaque and the apposition of a patch of dura mater. The authors want to underlie as the onset of IPP can be sudden, promoted by the resolution of the hypogonadism secondary to pituitary neoplasia, and contemporary to the normalization of testosterone levels.

Adenoma↗

PubMed1995

The effect of non-steroidal antiandrogen flutamide on luteinizing hormone pulsatile secretion in male-to-female transsexual subjects.

We evaluated LH pulsatile patterns before and 4 weeks after the oral administration of flutamide (750 mg/day) in 9 male-to-female transsexuals (age range 17-28 yr) requesting gender reassignment. Flutamide was given to explore the feedback role of androgens on the LHRH-LH unit in LH pulsatility in transsexuals. Seven normal age-matched men served as a control group, without receiving flutamide, due to ethical considerations. LH pulsatility was evaluated on samples collected every 15 min for 360 min. FSH, PRL, cortisol, SHBG and sex steroids were evaluated on pooled samples. LH pulses were analyzed by the Santen and Bardin algorithm, slightly modified. No differences in FSH, PRL, total- or free-testosterone, estradiol and SHBG levels were noted between transsexuals and controls. Normal circadian cortisol decline was observed in all subjects. Mean LH levels (p < 0.05) and LH pulses (p < 0.01) were significantly lower in transsexuals. Flutamide induced an increase in mean LH and testosterone levels (p < 0.01). After flutamide administration there was an increase in LH pulse frequency (P < 0.01) and the frequency and amplitude of LH pulses in transsexuals were restored to levels observed in controls. No differences in FSH, PRL or estradiol levels were found after flutamide. These data suggest that a decrease in LH pulse frequency could be an endocrine marker in male-to-female transsexuals. An increase in endogenous androgen negative feed-back could be speculated in these subjects. However, normal testosterone levels indirectly suggest that a normal that a normal qualitative LH secretion is maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

A technique for sorting rat gonadotropes using anti-LH or anti-FSH antibodies covalently attached to magnetic beads.

A technique for sorting live LH- and FSH-secreting cells was developed. After enzymatic dispersion, a suspension of pituitary cells from male rats castrated 7 days earlier was incubated in potassium chloride (KCI 50 mmol/l) for 30 min and gonadotropin outflow was provoked. Then, considering either LH or FSH as temporary surface markers, we positively selected the secreting cells by means of antibodies toward either LH (anti-LH beads) or FSH (anti-FSH beads) covalently attached to magnetic beads. The spontaneous secretion of LH and FSH overnight and the release induced by KCI the following morning were calculated. A population enriched in gonadotropes (16% of the total) able to secrete both gonadotropins was selected by means of anti-LH beads; this released 7 times as much LH as non-selected cells. A similar population (14% of the total) was selected by means of anti-FSH-coated beads; this produced 3.3 times as much LH as non-selected cells. In some experiments, the cells not previously sorted with anti-LH-coated beads were further incubated in the presence of anti-FSH beads, in an attempt to isolate a population secreting only FSH. A limited number of cells were sorted (6% of the total cells), able to produce both gonadotropins, but with a lower LH/FSH ratio. Similarly, those cells excluded by the selection with anti-FSH beads were further incubated with anti-LH beads, with a view to obtaining only-LH-secreting cells. However, both gonadotropins were still secreted by these cells (8% of the total), which had the highest LH/FSH ratio. In conclusion, fractions from castrated male rats that are enriched in gonadotropes contain cells that secrete both gonadotropins in vitro. The secretion of LH is prevalent. However, differences in the LH/FSH ratio between the populations sorted and changes from spontaneous to stimulated release are observed. This suggests that some gonadotropes might 'specialize' in releasing LH and others in releasing both LH and FSH.

Animals↗

PubMed1995

In vitro acute and prolonged effects of melatonin on purified rat Leydig cell steroidogenesis and adenosine 3',5'-monophosphate production.

The effects of melatonin (MLT; 4.3 pM to 4.3 microM) on rat Leydig cell steroidogenesis and cAMP production were investigated during 3-h LH (30 mIU/ml) stimulation. Having noted a dose-dependent inhibition of testosterone (T) release, we also tested MLT in the presence of the cAMP activator forskolin (1 microM), the phosphodiesterase inhibitor isobutylmethylxanthine (100 microM), a combination of these two, and LHRH (100 nM), a non-cAMP-mediated stimulus. Regardless of the stimulus, levels of T, androstenedione, and cAMP were reduced, whereas that of 17-hydroxyprogesterone was enhanced. Cells were also tested after prolonged exposure to MLT (215 nM for 16 h). When compared with data from cells not preincubated with MLT, cAMP and T levels were 30% higher during LH stimulation (30 mIU/ml); comparable during treatment with forskolin (1 microM), isobutylmethylxanthine (100 microM), or their combination; and reduced during LHRH (100 nM). Scatchard analysis did not reveal changes in LH receptors during prolonged MLT exposure. Our data show that MLT acutely reduces cAMP- and non-cAMP-stimulated T. This effect is linked in part to reduced cAMP production and in part to reduced 17-20-desmolase enzymatic activity, which, however, can occur even with non-cAMP-mediated stimulation. On the other hand, prolonged exposure to MLT results in sensitization of the LH-dependent adenylate cyclase activity.

Androgens↗

PubMed1995

Delayed puberty in males with beta-thalassemia major: pulsatile gonadotropin-releasing hormone administration induces changes in gonadotropin isoform profiles and an increase in sex steroids.

Patients with beta-thalassemia major often have pubertal delay, the etiology of which has not been fully elucidated. We investigated the pituitary-gonadal response to short-term subcutaneous pulsatile gonadotropin-releasing hormone (GnRH) administration (150 ng/kg body weight every 120 min for 7 days) in five young males (aged 13.6-19.0 years) affected by beta-thalassemia major and presenting signs of delayed puberty. Immunoreactive and bioactive gonadotropin levels were determined and their isoform profiles were examined, before and after GnRH treatment, in a pool of samples collected every 15 min for 240 min. Testosterone, androstenedione, 17-hydroxyprogesterone, dehydroepiandrosterone and 17 beta-estradiol were measured as markers of gonadal function on days 0, 1, 3, 5 and 7 of treatment. Five patients (aged 16.9-26.8 years) with confirmed diagnosis of idiopathic hypogonadotropic hypogonadism who were starting pulsatile GnRH therapy were also studied in the same protocol. Increased sex steroid levels were observed in both groups as a result of treatment. On day 7, the thalassemic patients had increased bioactive luteinizing hormone (LH) and follide-stimulating hormone (FSH), although immunoreactive LH and FSH were comparable to day 0. Moreover, fewer acidic and more basic immunoreactive and bioactive isoforms were noted in LH profiles on day 7. Similar results were observed in hypogonadal patients, who also had increased immunoreactive LH and FSH values. We suggest that the early stage of delayed puberty in thalassemia might be characterized by a neuroendocrine dysfunction resulting in an impaired hypothalamic GnRH release, which is inadequate for a proper pituitary stimulation. Pulsatile GnRH treatment seems to re-establish partially the correct pituitary-gonadal function.

17-alpha-Hydroxyprogesterone↗

PubMed1995

Ritanserin pharmacokinetics in abstinent chronic alcoholics.

Ritanserin is a thymosthenic agent with an extensive hepatic metabolism and long elimination half life in healthy volunteers. It has been used in abstinent chronic alcoholic patients showing an interesting performance in this condition. Ritanserin pharmacokinetics has only been evaluated in single dose healthy volunteer studies and, on the other hand, chronic use of the drug in alcoholic patients during withdrawal period could be anticipated. Therefore, the objective of the present study, is to assess the cumulating kinetics of the serotonin antagonist during chronic administration. Ten abstinent alcoholic patients were included in an open study. The drug was administered at a daily dose of 10 mg for 28 days and the active phase was preceded by a seven-day wash out period with placebo. Blood samples were taken on the 1st, and 28th, day of treatment, 24 hours after taking the drug. Urine samples were taken during the night before the second and 28th dose. Plasma and urine ritanserin concentration was measured by high performance liquid chromatography. Very large variations in initial and steady state concentrations (CV = 65 and 52% respectively) were found, which is reflected in the large variability of the calculated pharmacokinetic parameters. Ritanserin cumulation factor (R) was 6.9 +/- 8.3 (mean+SEM). Two patients showing extensive accumulation had prolonged elimination half lives (433 and 279 hours) that are explained mostly by an expansion of the volume of distribution and, to a lesser extent, by diminished clearance.

Adult↗

PubMed1995

Cholinergic modulation of growth hormone, prolactin and thyroid stimulating hormone responses to thyrotropin-releasing hormone in normal aging.

Endocrine changes occur during the normal aging process. These include alterations in GH, TSH and, to a lesser extent, PRL secretion. Pyrodistigmine (PD) increases basal GH secretion in a widely variable manner and partially reverses the blunted GH response to GHRH found in elderly subjects. The aims of this study were to verify the finding of a paradoxical GH response to TRH (200 micrograms iv) and to evaluate the effect of priming with PD (120 mg orally) on basal and TRH-stimulated GH, TSH and PRL secretion in 7 euthyroid subjects (aged 75-96 years). Hormonal responses after control saline and PD were also evaluated. PD did not modify TSH or PRL responses to TRH. A slight increase in GH secretion was observed after PD. A clear-cut increase in GH levels after TRH was found in 4 out of 7 subjects. TRH-induced GH secretion was significantly increased by pretreatment with PD. Functional abnormalities in the neuroendocrine control of GH secretion in aging could explain, at least in part, the appearance of GH release after TRH. Cholinergic neurotransmission, which is thought to be stimulated by PD administration, seems to be involved in the non-specific GH release after TRH administration in elderly subjects.

Age Factors↗

PubMed1995

Treatment of acromegaly with octreotide: effectiveness and tolerability of its pulsatile administration by portable pump.

This study was undertaken to evaluate effectiveness and tolerability of octreotide administered in active acromegaly by pulsatile means and compare these data with intermittent three-times-a-day therapy. We studied 13 acromegalics with active disease. All patients received octreotide subcutaneously administered in a pulsatile way using a portable pump delivering 25 micrograms every 120 minutes and in an intermittent way (100 micrograms three times daily) (TID). From pretreatment values (56.5 +/- 13.4 micrograms/L) the 24-h integrated mean GH levels (IC-GH) were significantly reduced both during pulsatile and TID octreotide administration (P < 0.01). IC-GH was significantly lower during pulsatile therapy (17.0 +/- 5.2 micrograms/L) than during TID (22.0 +/- 11.5 micrograms/L; P < 0.05). Before octreotide, IGF-I levels were 669.8 +/- 85.7 micrograms/L; during octreotide therapy they were reduced in 12/13 patients (TID 340.2 +/- 41.5 micrograms/L, pulsatile 338.1 +/- 55.3 micrograms/L; P < 0.01). A correlation between IC-GH and IGF-I levels was observed only during TID administration of octreotide (R = 0.652; P < 0.05). The 24-hour GH pattern fluctuated widely before the start of octreotide therapy. During TID administration, GH levels tended to rise again before the following octreotide injection; this did not occur during pulsatile therapy. Side effects were fewer during pulsatile (15%) than TID (31%) octreotide administration (NS). Asymptomatic gallstones appeared in 1 patient. In conclusion subcutaneous pulsatile octreotide administration in acromegalic patients by means of a small portable pump seems able to produce, a steadier control of GH-IGF-I hypersecretion and fewer side effects than TID administration at same dosage.

Acromegaly↗