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Biomedical subjects

M Boschetti

Publications and source records attributed to M Boschetti.

14 recordsLinked to original sources
PubMed2006

The IGF system in a case of Costello syndrome.

Costello syndrome is characterized by facial dysmorphia, hyperpigmented skin, palmar and plantar hyperkeratosis, curly hair, perioral and nasal papillomata (more rarely localized anally and on vocal cords), short stature, mental retardation and sociable personality. Although growth retardation is typical of Costello syndrome, its cause is not defined. We report on a 10-yr-old Caucasian girl affected by Costello syndrome with fasting hypoglycemia and short stature, associated low circulating levels of acid-labile subunit (ALS), relatively low levels of IGF-I and IGFBP-3, and normal IGF-II, mostly circulating in a binary complex with IGFBP-2 and -6 instead of in a 150 kDa ternary complex. The reduced ALS concentration and the consequent impaired formation of the circulating 150 kDa ternary complex can induce an accelerated clearance rate of IGF peptides and of IGFBP-3, contributing to the decreased IGF-I growth promoting activity in our patient. Moreover, the presence of IGF-II in the binary complex, which has been postulated to increase the insulin-like effects of these peptides, can explain, at least in part, the patient's asymptomatic fasting hypoglycemia.

Carrier Proteins↗
PubMed2005

Pituitary tumor disappearance in a patient with newly diagnosed acromegaly primarily treated with octreotide LAR.

We describe the case of an acromegalic patient primarily treated with octreotide LAR in whom the pituitary tumor disappeared after 18 months of treatment. A 68-yr-old woman, with clinical suspicion of acromegaly, was admitted to our Unit with the ultrasonographical evidence of cardiac hypertrophy, arrhythmias, right branch block and interatrial septum aneurism. She referred hands and feet enlargement since the age of 30 and facial disfigurements since the age of 50. At the age of 45 she underwent surgery for carpal tunnel syndrome and at the age of 61 an euthyroid nodular goiter was diagnosed. Hormonal evaluation showed elevated circulating GH levels (25+/-3.2 ng/ml), not suppressible after oral glucose load, and elevated IGF-I levels (646 ng/ml), whereas the remaining pituitary function was normal. Visual perimetry was normal, whereas magnetic resonance imaging (MRI) showed an intrasellar pituitary adenoma with maximal diameter of 9 mm. In order to improve cardiovascular function before surgery, the patient started octreotide LAR 20 mg every 4 weeks for 3 months. Then based on IGF-I values, the dose was adjusted to 30 mg. After 6 months a second MRI showed significant tumor reduction (>50% of baseline maximal diameter), GH and IGF-I were within the normal range and the patient continued the treatment. After one-year therapy, an improvement of cardiac alterations was recorded and the patient was referred to the neurosurgeon. However, she refused the operation. At 18-month follow-up, MRI showed the complete disappearance of direct and indirect signs of pituitary adenoma. To our knowledge, this is the first case of complete radiological remission of pituitary tumor during octreotide LAR treatment in acromegaly.

Acromegaly↗
PubMed2005

Potential indications for somatostatin analogues: immune system and limphoproliferative disorders.

Among hormones and neuropeptides influencing the immune system, somatostatin seems to play a key role not only in inhibiting specific immune cell activities, but also in promoting selected functions of particular immune cell subsets. Indeed, controversial effects have been observed in experimental conditions where somatostatin seems to stimulate certain cell functions, such as secretion of specific products (immunoglobulin, cytokines), cell migration and adhesion to extracellular matrix components. However, interestingly, cortistatin (CST), a neuropeptide that strongly resembles somatostatin, from both the structural and functional points of view, seems to have potential roles in regulating immune responses, as well as other lymphoid cell functions. The unexpected wide distribution of CST in a number of human organs, but particularly in immune cells, points to a broader physiological role of CST than previously presumed. The actions of somatostatin and its synthetic analogs (SSA) are mediated by five membrane G protein-coupled receptors subtypes (SSTR1-5), displaying a tissue specific distribution. The majority of somatostatin-target tissues, including lymphoid tissues, may co-express multiple somatostatin receptor (SSTR). The number of SSTRs in lymphoid cells is significantly lower compared to neuroendocrine tissues. However, the presence of receptors allowed the localization by in vivo SSTR scintigraphy of lymphoproliferative disorders, as well as granulomatous and autoimmune diseases. In specific cases, this technique may contribute to establishing the diagnosis and staging the disease. Recent studies evaluating the specific and quantitative SSTR distribution in lymphoid organs and cells, in both normal conditions and immune disorders, have largely contributed to better understand the phenomenology of in vivo receptor imaging and also the involvement of the different SSTR in determining the uptake of radiolabeled SSAs. Moreover, since lymphomas are highly radiosensitive malignancies, a promising approach in refractory patients with malignant lymphomas may be represented by radionuclide-targeted therapy with radioactive-coupled SSAs combined with gene therapy. This latter technique seems effective in inducing the expression or increasing the number of given SSTR in order to ameliorate the impact of radionuclide-targeted therapy. Medical treatment of lymphoproliferative diseases with currently available synthetic analogs have produced unsatisfactory and conflicting results. This might be due to the affinity of the current available SSAs for specific SSTR. However, the synthesis of new compounds with distinct properties has reopened a challenge in this field. The application of receptor-based localization and anti-tumor strategies should also be taking into account the new knowledge recently emerged on the physiopathology of neuropeptide receptors: firstly, neuropeptide receptor homo- and heterodimerization, which may involve different subtypes of SSTRs, as well as other neuropetide receptors, and secondly, the role of endogenous SSTR ligands, such as CST.

Humans↗
PubMed2001

HIV-1 Rev transactivator: a beta-subunit directed substrate and effector of protein kinase CK2.

The phosphorylation of HIV-1 Rev by protein kinase CK2 is strictly dependent on the regulatory beta subunit of the kinase and is deeply affected by conformational changes of the substrate outside the phosphorylation site. Here we show that Rev modulates a variety of CK2 properties, including autophosphorylation, catalytic activity toward calmodulin, and susceptibility to polycationic effectors, whose common denominator is the involvement of the beta subunit. Rev's two major CK2 sites are located at its N-terminus, immediately adjacent to a helix-loop-helix motif. By comparing the behaviour of full-size Rev with that of synthetic peptides reproducing, with suitable modifications, its N-terminal 26 amino acids including the phosphoacceptor site (Ser 5, Ser 8) and amphipathic helix-1, it appears that the functional interaction of the N-terminal portion of Rev with the N-terminal domain of the beta subunit must rely on both electrostatic and hydrophobic interactions. The former mainly involve Rev's arginine-rich domain (residues 35-50) in helix-2, while the latter are mostly mediated by residues 12-24 of helix-1. These data disclose the possibility that, besides displaying protective, regulatory and targeting properties with respect to the catalytic subunit, the CK2 beta subunit also plays a role as a docking site for a subset of CK2 substrates.

Amino Acid Motifs↗
PubMed2000

Cooperative modulation of protein kinase CK2 by separate domains of its regulatory beta-subunit.

Protein kinase CK2 ("casein kinase 2") holoenzyme is composed of two catalytic (alpha and/or alpha') and two regulatory beta-subunits. A truncated form of the beta-subunit lacking its C-terminal region (betaDelta171-215) has lost the ability to stably associate with the catalytic subunits and to display a number of properties which are mediated by structural elements still present in its sequence, notably down-regulation of catalytic activity, autophosphorylation, and responsiveness to polycationic effectors. All these functions are restored by simultaneous addition of a synthetic peptide reproducing the deleted fragment, beta170-215, which is able to associate with the catalytic subunits and to stimulate catalytic activity. This peptide includes a segment displaying significant sequence similarity with a region of cyclin A which interacts with the PSTAIRE motif of CDK2 eliciting its catalytic activity. A peptide reproducing this sequence (beta181-203), but not its derivative in which three nonpolar side chains have been replaced by polar ones, interacts with the alpha-subunit and stimulates its catalytic activity; it also partially restores the ability of truncated betaDelta171-215 to autophosphorylate. These data disclose the essential role of a structural module located between residues 181 and 203 in conferring regulatory properties to the beta-subunit of CK2.

Amino Acid Sequence↗
PubMed2000

Unique features of HIV-1 Rev protein phosphorylation by protein kinase CK2 ('casein kinase-2').

The HIV-1 Rev transactivator is phosphorylated in vitro by protein kinase CK2 at two residues, Ser-5 and Ser-8; these sites are also phosphorylated in vivo. Here we show that the mechanism by which CK2 phosphorylates Rev is unique in several respects, notably: (i) it is fully dependent on the regulatory, beta-subunit of CK2; (ii) it relies on the integrity of an acidic stretch of CK2 beta which down-regulates the phosphorylation of other substrates; (iii) it is inhibited in a dose-dependent manner by polyamines and other polycationic effectors that normally stimulate CK2 activity. In contrast, a peptide corresponding to the amino-terminal 26 amino acids of Rev, including the phosphoacceptor site, is readily phosphorylated by the catalytic subunit of CK2 even in the absence of the beta-subunit. These data, in conjunction with the observation that two functionally inactive derivatives of Rev with mutations in its helix-loop-helix motif are refractory to phosphorylation, indicate the phosphorylation of Rev by CK2 relies on conformational features of distinct regions that are also required for the transactivator's biological activity.

Amino Acid Sequence↗
PubMed1996

[Medical nephropathies: what has changed in 20 years].

The authors analyse the series of patients with medical nephropathy undergoing renal biopsy between 1973 and 1993 in order to make a diagnostic and prognostic comparison between the first (ID) and second (IID) decade. Clinical indications for biopsy, which became more precise during the second decade, led to the diagnosis of fewer patients with normal histology; the introduction of ME and IF allowed non-significant histological conditions to be reduced during IID; echo-guided biopsy has led to a reduced number of post-biopsy complications in IID compared to ID. Epidemiological analysis reveals the reduction of focal glomerulosclerosis in IID in favour of glomerulonephritis with IgA deposits in correlation with the use of IF; the increase in mebranous glomerulonephritis secondary to increased antigenic stimuli; reduced acute post-infective glomerulonephritis and membrane-proliferative glomerulonephritis owing to an improved prophylaxis of sources of infection. Among the patients undergoing renal biopsy and commencing dialysis an increase was observed in IID in the number of cases of membranous glomerulonephritis or caused by IgA deposits. There was an increased interval between biopsy and the start of dialysis in IID compared to ID, in spite of fewer patients receiving immunosuppressive therapy. This was probably due to the increased number of pathologies with a slower evolution, thus justifying the postponement of the start of dialysis.

Adult↗
PubMed1994

Uric acid homeostasis in lean and obese girls during pubertal development.

Serum uric acid concentration and fractional excretion were evaluated in lean (n = 67) and obese (n = 56) girls before and during pubertal development. In both lean and obese girls, uricemia gradually increased as puberty advanced. Obese girls were hyperuricemic compared with lean controls (prepubertal: 184 +/- 83 v 130 +/- 29 mumol/L, P = .007; Tanner stage II-III: 190 +/- 53 v 178 +/- 47 mumol/L, NS; Tanner stage IV-V: 232 +/- 53 v 191 +/- 53 mumol/L, P = .02). Fractional excretion of urate decreased with puberty in lean girls (6.46% +/- 2.29%, 4.61% +/- 2.48%, and 3.54% +/- 1.84%), but not in obese subjects (3.74% +/- 2.27%, 4.01% +/- 1.90%, and 4.26% +/- 2.26%). Urate homeostasis was similar in prepubertal obese girls and in adolescent lean controls. We conclude that an increased serum urate concentration occurring at puberty may be due to decreased renal clearance of urate in lean girls, and at least in part to urate overproduction in obese subjects. Obesity may prematurely evoke changes in urate metabolism usually observed at puberty.

Adolescent↗
PubMed1983

[Antithrombin III and fibrinogen after surgical interventions on the abdomen and heart].

We have explored the changes of plasma concentrations of antithrombin III and fibrinogen in patients recovering from major abdominal and cardiac surgery. In one group of patients subjected to major abdominal surgery we detected a statistically significant reduction of antithrombin III in the second and third postoperative day, followed by return to normal values in the fourth or fifth day. Fibrinogen, instead, increased to as much as 180% of the preoperative value in the first four postoperative days and reverted slowly to preoperative values between the fourth and the eighth day. In another group of patients subjected to cardiac surgery procedures utilizing the heart-lung machine, however, we found no significant reductions of antithrombin III in the early postoperative period. These results suggest the possible influence of local tissue factors affecting the plasma levels of antithrombin III differently in the two types of surgery under discussion. The patients subjected to extracorporeal circulation, on the other hand, showed a depletion of plasma fibrinogen down to less than 30 or 40% of preoperative values. This may reflect activation of coagulation processes and the considerable sequestration of fibrin at some interfaces of the heart-lung machine.

Abdomen↗
PubMed1979

[Hemorrhagic duodenal ulcer].

The authors report their experience in the treatment of hemorrhagic duodenal ulcers in 19 patients (17 men, 2 women) between 1972 and 1977. They compare the results obtained with the two methods adopted, namely gastric resection and local hemostasis of the ulcer followed by troncular or selective vagotomy, or selective proximal vagotomy and pyloroplasty. The results so analyzed speak definitely in favor of the latter procedures as opposed to gastrectomy.

Adult↗
PubMedDate not supplied

[High-efficiency membranes and the dialysis solution].

During this work through the total bacterial count and of the pseudomonas and the determination of the positive substances to Limulus Amebocyte Lysate test, bacterial pollution of the liquid bicarbonate concentrate has been determined together with the influence that preparation conditions and the entity of interval between the said preparation and utilization of concentrates have on it. Through the evaluation of the cardiac rate and the systemic arterial pressure, we have studied the influence of the bacterial pollution on the clinical of the patient. Analysing the obtained data we can point out that the liquid bicarbonate concentrate present an elevated degree of contamination which feels the effects of the production and storage procedures. The remark of inverse correlation between systemic arterial pressure and endotoxin level of the dialysate seems to reconfirm the importance of the bacterial contamination on the clinical of the patient.

Bacteria↗