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A Avallone

Publications and source records attributed to A Avallone.

34 records · Page 2Linked to original sources
PubMed1994

Alpha 1A- and alpha 1B-adrenergic receptors mediate the effect of norepinephrine on cytosolic calcium levels in rat PC C13 thyroid cells: thyrotropin modulation of alpha 1B-linked response via a adenosine 3',5'-monophosphate-protein kinase-A-dependent pathway.

The aim of the present study was to characterize the adrenergic receptors mediating the effects of norepinephrine on PC C13 rat thyroid cells and identify the molecular mechanisms by which TSH regulates the noradrenergic response. We studied TSH regulation of norepinephrine-induced cytosolic calcium increase by means of the fluorescent probe fura-2. In PC C13 cells grown and maintained in a medium containing TSH (PC C13 6H), norepinephrine caused a higher increase in cytosolic calcium than in PC C13 starved from TSH 5 days before the experiments (PC C13 5H). In both group of cells the calcium response to norepinephrine was concentration dependent and reduced by the removal of extracellular calcium ions. Reintroduction of TSH in the culture medium of the PC C13 5H cells induced the recovery of the norepinephrine-stimulated intracellular calcium rise similarly to that in the native PC C13 6H. This effect was complete after a 48-h incubation period and was abolished by the simultaneous treatment of the cells with the protein synthesis inhibitor cycloheximide, suggesting that TSH may stimulate the synthesis of alpha 1-adrenergic receptors in PC C13 cells. Because in these cells we found that TSH increased cAMP levels as well as inositol phosphate production, we tested whether the activation of a protein kinase-A and/or protein kinase-C was involved in TSH regulation of the adrenergic response. We found that the treatment of PC C13 5H cells with forskolin restored the effect of norepinephrine on the calcium level, and that KT5720, an inhibitor of the protein kinase-A, was able to prevent the recovery of the noradrenergic response induced by the readdition of TSH to the culture medium of PC C13 5H. Conversely, treatment of PC C13 5H cells with the protein kinase-C activator phorbol 12-myristate 13-acetate was ineffective. Norepinephrine also stimulated inositol phosphate production in PC C13 6H and, to a lesser extent, in PC C13 5H, but it did not affect the cAMP levels in the two groups of cells. To characterize alpha 1-adrenergic receptor subtypes mediating the effects of norepinephrine in PC C13 cells, we used antagonists of alpha 1A and alpha 1B receptors (WB4101 and chlorethylclonidine respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1993

Effect of acetyl-L-carnitine treatment on brain adenylate cyclase activity in young and aged rats.

The aim of the present study has been to evaluate the effect of acetyl-L-carnitine (ALCAR) on brain adenylate cyclase (AC) activity in adult and aged rats. In in vitro studies, ALCAR (1, 10 and 100 microM) did not exert any effect on frontal cortex basal AC activity. Acute and subchronic administrations of ALCAR were carried out in 4- and 25-month-old male Fisher rats and AC activity was determined in rat frontal cortex under both basal and stimulated conditions. The acute treatment of young rats with ALCAR (100 and 500 mg/kg s.c.) did not affect AC activity, whereas the subchronic administration of 250 mg/kg s.c. ALCAR enhanced the stimulation of AC by carbamylcholine (CCh), norepinephrine (NE) and dopamine (DA), without affecting the basal AC activity. Basal AC activity in old rats was lower than in young rats and was not modified by acute and subchronic ALCAR administration. Moreover, the response of the enzyme to CCh, NE and DA was potentiated by the subchronic administration of ALCAR. The concentration-response curve of CCh stimulation of AC activity in ALCAR-treated rats is shifted to the left in both young and aged rats. We conclude that ALCAR, subchronically administered, is able to enhance receptor-stimulated AC response in frontal cortex of both young and aged rats.

Acetylcarnitine↗
PubMed1993

Direct effect of adenosine on prolactin secretion at the level of the single rat lactotroph: involvement of pertussis toxin-sensitive and -insensitive transducing mechanisms.

We studied the effect of adenosine on prolactin secretion by the anterior pituitary, and the transduction mechanisms whereby the purine exerts its action. Adenosine inhibited prolactin release in basal and in vasoactive intestinal peptide (VIP)- or TRH-stimulated conditions. Pertussis toxin pretreatment reduced the inhibition of VIP-stimulated prolactin secretion which was induced by adenosine, while it completely abolished the effect of the purine on TRH-evoked prolactin release. In membrane preparations of anterior pituitary cells, adenosine reduced the adenylate cyclase activity stimulated by VIP. Such an inhibition was not blocked by pertussis toxin pretreatment. Furthermore, the purine reduced TRH-stimulated inositol phosphate production in cultured anterior pituitary cells, an effect that was reversed by pretreatment with pertussis toxin. In addition, the nucleoside did not significantly affect the TRH-induced rise in intracellular calcium. In conclusion, our data show that adenosine inhibits prolactin secretion, acting on purinergic receptors coupled to the adenylate cyclase enzyme and phospholipase C. The effect of the nucleoside on adenylate cyclase seems to be achieved either by the involvement of an adenosine receptor coupled to the catalytic subunit of the enzyme via a pertussis toxin-sensitive G protein, or by the activation of a site directly coupled to the catalytic subunit of the adenylate cyclase (the P site). Its effect on phospholipase C seems to be mediated by a purinergic receptor coupled to the intracellular effector via a pertussis toxin-sensitive G protein.

Adenosine↗
PubMed1992

Dopamine and somatostatin inhibition of prolactin secretion from MMQ pituitary cells: role of adenosine triphosphate-sensitive potassium channels.

The sulfonylurea glibenclamide, which is known to block ATP-sensitive potassium channels, increases, in a dose-dependent manner, the release of PRL from MMQ pituitary cells. Glibenclamide does not reduce the dopaminergic inhibition of forskolin-stimulated PRL secretion; conversely it almost completely abolishes the inhibitory effect of somatostatin (SRIF) on this parameter. The sulfonylurea dose dependently increases basal [Ca++]i, without affecting the increase in [Ca++]i induced by high concentrations of extracellular potassium. Glibenclamide does not modify dopamine-induced [Ca++]i reduction, whereas it abolishes the inhibitory effect of SRIF on basal [Ca++]i. In the presence of diazoxide, an opener of ATP-sensitive potassium channels, which lowers basal [Ca++]i, dopamine still reduces [Ca++]i whereas SRIF does not induce a further decrease. Glibenclamide induces the depolarization of the cell membrane and prevents the SRIF-evoked hyperpolarization. The hyperpolarization of the cell membrane induced by dopamine is not modified by glibenclamide. Diazoxide induces a cell membrane hyperpolarization that is enhanced by dopamine but not by SRIF. Finally, glibenclamide does not affect basal and stimulated adenylate cyclase activity. In conclusion, our findings show that, in MMQ cells, glibenclamide stimulates PRL release, suggesting an involvement of ATP-sensitive potassium channels in the regulation of PRL secretion. The reversal by glibenclamide of the effects of SRIF on calcium homeostasis, membrane potential, and PRL release suggests that this type of potassium channel participates to the somatostatinergic inhibition of PRL secretion. Conversely, we found that glibenclamide does not modify the dopaminergic inhibition of PRL secretion and second messenger systems, suggesting that ATP-sensitive potassium channels may not be involved in the inhibitory effect of dopamine on PRL release.

Adenosine Triphosphate↗
PubMed1988

Pelvic lipomatosis: diagnosis and characterization by magnetic resonance imaging.

While the number of reported cases of pelvic lipomatosis has been relatively small, this entity's prevalence is probably underestimated. Disease progression can cause hydroureteronephrosis and renal failure, and clinical follow-up is mandated after diagnosis. Diagnosis is based on detection of characteristic findings in conventional radiographs and computed tomographic (CT) images. We report here the magnetic resonance imaging (MRI) features of pelvic lipomatosis in 5 male patients, 2 of whom ultimately required placement of a ureteral stent to alleviate mechanical obstruction. Multiplanar MRI not only allows diagnostic confirmation comparable to that possible with CT but also provides delineation of cephalad displacement of the bladder base, elongation of the bladder neck and posterior urethra, and elevation of the prostate gland. The MR images show characteristic medial and superior displacement of the seminal vesicles and show fatty tissue separating the prostate gland from the rectum. The noninvasive nature and low biological risk of MRI are desirable features, particularly when serial evaluation of pelvic anatomic distortion is necessary.

Adult↗
PubMed1987

Prostatic carcinoma: staging by clinical assessment, CT, and MR imaging.

The sensitivity, specificity, accuracy, and positive and negative predictive values of clinical assessment, computed tomography (CT), and magnetic resonance (MR) imaging were compared in the differentiation of stage B from stage C prostatic carcinoma. Forty-six patients who had undergone radical prostatectomy were included in the study. Surgical-pathologic staging was considered the "truth measure." Clinical staging had an accuracy of 61%, and CT, 65%. Accuracy for MR imaging depended on the instrument parameters and plane of section used. When only transverse T1-weighted images were analyzed, MR accuracy was 61%. However, when transverse T1- and T2-weighted images supplemented by additional T2-weighted coronal or sagittal images were studied, accuracy increased to 83%. At present, MR imaging is the most accurate diagnostic modality for the local staging of carcinoma of the prostate, but for optimal results, multiple sequences and two orthogonal planes of imaging are needed.

Aged↗
PubMed1987

MR imaging of the prostate gland: normal anatomy.

MR images of the male pelvis in 55 subjects were analyzed retrospectively for depiction of the zonal anatomy of the prostate gland as related to different repetition (TR) and echo (TE) times, slice thickness, plane of imaging, chronologic age of the patient, and different magnetic field strengths. With imagers operating at 0.35 and 1.5 T, T2-based tissue-contrast images were needed for the demonstration of the internal anatomy of the prostate gland. The display of zonal anatomy was improved when continuous 0.5-cm slices were used. Evaluating sequential sections, the peripheral, central, and transition zones could be differentiated. The peripheral zone showed higher signal intensity than either the central or transition zone and was discerned in the coronal, sagittal, and transverse planes. The central zone was of low signal intensity and was well displayed in the coronal and sagittal planes. The central zone was seen in 31 of the 32 young men (aged 25-35 years) but in only eight of the 23 older men (aged 40 years and older). The transition zone had intrinsic MR parameters similar to the central zone, and the two could be distinguished from each other only by the knowledge of their respective anatomic location. The low-intensity transition zone blended with the periurethral glands and the preprostatic sphincter. The transition zone was of homogeneous low signal intensity in young men but varied in size and signal intensity in older men. Such a detailed display of the prostate zonal anatomy offers a unique potential for the evaluation of prostatic physiology and disease.

Adult↗
PubMedDate not supplied

[Early evaluation using PET-FDG of the efficiency of neoadjuvant radiochemotherapy treatment in locally advanced neoplasia of the lower rectum].

BACKGROUND AND PURPOSE: Preoperative chemoradiation allows downstaging of locally advanced rectal cancer and in selected patients also a sufficient downsizing to ensure sphincter preservation. Selection of patients warranting a preoperative approach is improved by magnetic resonance imaging (MRI) which is able to define the involvement of mesorectal circumferential margin. Similarly it would be crucial to define the response to chemoradiation during the treatment but traditional morphologic imaging techniques may fail in differentiating neoplastic tissue from scarring. PET-FDG has been successfully used in the detection of metastatic colorectal cancer allowing imaging of deposits as small as 0.5 cm and may have a role in evaluating early response to chemoradiation. METHODS: In the present study, in patients with T3-T4 rectal cancer undergoing preoperative chemoradiation PET-FDG and flow cytometry analysis on endoscopic biopsy specimen have been performed before, during and after preoperative chemoradiation. RESULTS: Chemoradiation treatment has been successful in terms of downsizing and downstaging of the tumor. PET-FDG was able to demonstrate local response at only ten-fifteen days after the beginning of neoadjuvant therapy, also identifying non responding patients. CONCLUSIONS: FDG-PET may have a role in defining the response to chemoradiation and modulate the treatments strategy in patients with advanced rectal cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

Multidisciplinary approach to locally advanced rectal cancer: results of a single institution trial.

Locally advanced rectal cancer carries out a dismail prognosis despite optimal surgery in terms of local and distant relapses. Neoadjuvant chemoradiation offers good results with tumor downstaging and downsizing and leads to more radical surgery with conservative intent. Selection of patients and an intensive chemotherapy may improve long term results. Our experience with a combined polichemotherapy and radiotherapy for low advanced rectal cancer is presented.

Combined Modality Therapy↗