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Biomedical subjects

E Landi

Publications and source records attributed to E Landi.

At least 19 recordsLinked to original sources
PubMed2006

Incidental small ampullary somatostatinoma treated with ampullectomy 2 years after diagnosis.

Somatostatinomas are rare tumors; ampullary somatostatinomas are very rare. We report a case of a small pure somatostatin-producing neuroendocrine tumor of ampulla of Vater in a 54-year-old woman with neither neurofibromatosis nor somatostatinoma syndrome, "incidentally" discovered during an abdominal computed tomography. The patient initially refused other adjunctive exams but after 2 years she was admitted, presenting with itch, night sweats, severe fatigue, and unintentional weight loss. The size of the tumor (1.5 cm) and the other radiologic findings had not changed since the abdominal CT scan 2 years before. The somatostatin, gastrin, glucagons, serotonin, vasoactive intestinal peptide, dopamine, norepinephrine, epinephrine, and calcitonin plasma levels were normal. ERCP-obtained biopsies revealed a neuroendocrine tumor with psammoma bodies; immunohistochemical profile was positive for chromogranin and somatostatin. The patient underwent surgery; intraoperative histologic examination of lymph nodes sampling of perihepatic and periduodenal lymph nodes was negative for metastasis. We performed, therefore, a transduodenal ampullectomy. The patient continues to do well at 3 years' follow-up with no evidence of local or distance recurrence of disease.

Ampulla of Vater↗
PubMed2005

HA/alginate hybrid composites prepared through bio-inspired nucleation.

Poorly crystalline apatite has been directly nucleated on self-assembling alginate chains by neutralization synthesis to obtain a biomimetic artificial bone-like composite. It has been observed that in preparing HA/alginate composites, Ca2+ ions present on the apatitic surface cross-link the alginate chains to produce a material with different morphology and thermal stability, both functions of the HA/alginate weight ratio. In vitro tests were performed on different samples in terms of both the HA/alginate ratio and synthesis temperature. All the samples were cultured for seven days with MG63 osteoblast-like cells and then underwent morphological and biochemical analyses (MTT and ALP tests). Scaffolds showed a different solubility into the culture media, which was related to the temperature of synthesis and to the HA/alginate ratio. All our data confirm the ability of the tested materials to favour cell growth and to maintain their osteoblastic functionality, at least during the examined period.

Alginates↗
PubMed2005

From biomimetic apatites to biologically inspired composites.

Hydroxyapatite is an elective material for bone substitution. In this outline of our recent activity the crucial role of nanostructured ceramics in the design and preparation of ceramic scaffolds will be described, focussing on our more recent interest in biomimetic apatites, in particular apatites containing HPO42- CO32- and Mg2+ which are similar to the mineral component of bone. The paper describes such nanostructured products and, in particular, innovative synthetic techniques capable of yielding powders with higher reactivity and bioactivity. However, so far the characteristics of artificial bone tissues have been shown to be very different from those of natural bone, mainly because of the absence of the peculiar self-organizing interaction between apatites and the protein component. This causes modification of the structure of apatites and of the features of the overall composite forming human bone tissue. Therefore, attempts to mimic the features and structure of natural bone tissue, leading toward so-called bio-inspired materials, will be speculated upon. New techniques used to reproduce a composite in which a nanosize blade-like crystal of hydroxyapatite (HA) grows in contact with self-assembling fibres of natural polymer will be presented. In this specific case, the amazing ability of biological systems to store and process information at the molecular level, nucleating nanosize apatites (bio-inspired material), is exploited.

Animals↗
PubMed2005

High-resolution 3D scaffold model for engineered tissue fabrication using a rapid prototyping technique.

Rapid prototyping, automatic image processing (computer-aided design (CAD)) and computer-aided manufacturing techniques are opening new and interesting prospects for medical devices and tissue engineering, especially for hard tissues such as bone. The development of a bone high-resolution scaffold prototype using these techniques is described. The results testify to the fidelity existing between microtomographic reconstruction and CAD. Furthermore, stereolithographic manufacturing of this scaffold, which possesses a high degree of similarity to the starting model as monitored by morphological evaluations (mean diameter 569 +/- 147 microm), represents a promising result for regenerative medicine applications.

Bone Substitutes↗
PubMed2003

Porous phosphate-gelatine composite as bone graft with drug delivery function.

The design and synthesis of porous phosphate-gelatine composite implant which mimicks the structure of natural bone and has drug delivery function is proposed. Gelatine reproducing the proteinaceous part of bone was cross-linked in order to modulate its solubility in the physiologic fluids. The kinetic of gelatine release from ceramic matrix was also evaluated as model of the release of any therapeutic compound which can be loaded into gelatine.

Journal Article↗
PubMed2001

NTB-A [correction of GNTB-A], a novel SH2D1A-associated surface molecule contributing to the inability of natural killer cells to kill Epstein-Barr virus-infected B cells in X-linked lymphoproliferative disease.

In humans, natural killer (NK) cell function is regulated by a series of receptors and coreceptors with either triggering or inhibitory activity. Here we describe a novel 60-kD glycoprotein, termed NTB-A, that is expressed by all human NK, T, and B lymphocytes. Monoclonal antibody (mAb)-mediated cross-linking of NTB-A results in the induction of NK-mediated cytotoxicity. Similar to 2B4 (CD244) functioning as a coreceptor in the NK cell activation, NTB-A also triggers cytolytic activity only in NK cells expressing high surface densities of natural cytotoxicity receptors. This suggests that also NTB-A may function as a coreceptor in the process of NK cell activation. Molecular cloning of the cDNA coding for NTB-A molecule revealed a novel member of the immunoglobulin superfamily belonging to the CD2 subfamily. NTB-A is characterized, in its extracellular portion, by a distal V-type and a proximal C2-type domain and by a cytoplasmic portion containing three tyrosine-based motifs. NTB-A undergoes tyrosine phosphorylation and associates with the Src homology 2 domain-containing protein (SH2D1A) as well as with SH2 domain-containing phosphatases (SHPs). Importantly, analysis of NK cells derived from patients with X-linked lymphoproliferative disease (XLP) showed that the lack of SH2D1A protein profoundly affects the function not only of 2B4 but also of NTB-A. Thus, in XLP-NK cells, NTB-A mediates inhibitory rather than activating signals. These inhibitory signals are induced by the interaction of NTB-A with still undefined ligands expressed on Epstein-Barr virus (EBV)-infected target cells. Moreover, mAb-mediated masking of NTB-A can partially revert this inhibitory effect while a maximal recovery of target cell lysis can be obtained when both 2B4 and NTB-A are simultaneously masked. Thus, the altered function of NTB-A appears to play an important role in the inability of XLP-NK cells to kill EBV-infected target cells.

Animals↗
PubMed1997

Sintering and characterization of HA and TCP bioceramics with control of their strength and phase purity.

HA and beta-TCP-based ceramics were prepared using commercial powders. Powder characteristics were defined and the processing parameters studied, aimed at the production of samples with improved microstructural and mechanical properties. The behaviour of HA powder subjected to various thermal treatments was investigated in order to control the formation of secondary phases (alpha- and beta-TCP) during sintering. The optimal thermal treatment required to prepare pure beta-TCP powder from the precursors (HA and DCP) was determined and the sintering method required to prepare fully dense beta-TCP completely free from alpha-form, was identified. Translucent hot-pressed beta-TCP ceramics with potential applications in aesthetic restorative prostheses were prepared and characterized. The interval of existence of alpha-TCP and alpha-TCP as secondary products was also defined. Crystallographic analysis was carried out on the imperfectly known low-temperature alpha-TCP phase, and a proper monoclinic unit cell determined.

Journal Article↗
PubMed1994

Straight ileo-anal anastomosis with myectomy as an alternative to ileal pouch-anal anastomosis in restorative proctocolectomy.

Restorative proctocolectomy with various types of reservoir is widely used in the elective surgery of ulcerative colitis and familial adenomatous polyposis. Both, advantages and disadvantages of this procedure are well known and documented. Straight ileo-anal anastomosis (IAA) yields unsatisfactory clinical results due to the lack of storage capacity of the distal ileum and the frequency of bowel movements related to high pressure ileal waves. In an attempt to create an alternative to the above procedures, we have performed a straight ileo-anal anastomosis with two rectangular (10 cm x 1 cm) myectomies down to 2 cm, above the anastomotic line. The two myectomies are spaced at 120 degrees to each other and to the mesenteric border of the ileal loop. The rationale of this approach is to reduce the peristaltic drive of the ileum by weakening the muscular wall. This study presents the results in three patients operated on with this new method in the last year.

Adult↗
PubMed1994

[Liver regeneration: the metabolic aspects].

In the light of contributions from the literature, the authors describe their experience with metabolic problems in patients who have had a hepatectomy. The initial post-operative phase is characterised by changes proportional to the amount of parenchymal loss, consisting of a reduction in gluconeogenesis and visceral protein synthesis, accentuation of muscle proteolysis, and a slowing down of detoxifying activity with the accumulation of catabolic substrates, such as aromatic amino acids, which cannot be metabolised. However, provided that the operated liver is not cirrhotic and that the vasculo-biliary part of the remaining segments is left intact, the regeneration of the remaining parenchyma is completed within a few days and metabolic haemostasis of glycoproteins appears to be almost completely restored within the first week. The changes in the amino acid profile and their molar ratio, though transient, confirm the benefits of nutritional support that includes selective amino acids in the initial post-operative phase.

Amino Acids↗
PubMed1991

[Proctocolectomy and mechanical ileo-anal anastomosis without mucosectomy].

The present study compared the outcome in a small series of patients (7 cases) who underwent total proctocolectomy without mucosal proctectomy and stapled ileal pouch-anal anastomosis, constructed at the apex of the anal transitional zone, with our previous experience (17 cases) in which the ileal pouch was anastomosed at the dentate line after mucosectomy. Though not statistically significant, our limited experience showed excellent clinical results with better continence and discriminating ability between gas and faeces in the former group. The resting anal pressure profile showed no chances in the postoperative period. The operation time was significantly reduced compared with our previous approach which was a time-consuming procedure. Furthermore, a reduced risk of complications (pelvic sepsis, haemorrhage) was observed.

Adult↗
PubMed1990

Proctocolectomy and stapled ileo-anal anastomosis without mucosal proctectomy.

The present study compared the outcome of a small series of patients (7 cases) who underwent total proctocolectomy without mucosal proctectomy and stapled ileal pouch-anal anastomosis made at the apex of the anal transitional zone, with our previous experience (17 cases) in which the ileal pouch was anastomosed at the dentate line after mucosectomy. Though not statistically significant, our limited experience showed excellent clinical results with better continence and discriminating ability of flatus from faeces in the former group. The resting anal pressure profile was not changed postoperatively. The operation time was significantly reduced compared with our previous approach which was a time-consuming procedure. There was an indication that risk of complications (pelvic sepsis and haemorrhage) was less.

Anal Canal↗
PubMed1987

Evaluation of a new antihypertensive agent ketanserin versus methyldopa in the treatment of essential hypertension in older patients: an international multicenter trial.

The serotonergic antagonist ketanserin (K) was compared to methyldopa (M) in a four-center international study in 119 hypertensive patients over 50 years of age. After a 4-week placebo run-in period, patients randomly received K (20-40 mg b.i.d.) or M (250-500 mg b.i.d.) for 3 months. The drugs were given in monotherapy for at least 1 month, then a diuretic could be added if blood pressure remained abnormally high. For the patients on monotherapy, active drug was replaced by placebo at the end of the 3-month period until the patients were hypertensive again. K and M had a similar effect on systolic blood pressure, but diastolic blood pressure was reduced significantly more by K than by M. Significantly more patients had their blood pressure normalized in the K group (75%) than in the M group (49%). The twice daily dosage schedule caused trough blood pressure control with both drugs. No rebound hypertension occurred at discontinuation of treatment. Monotherapy with K caused a decrease in heart rate (-5 beats/min) while M produced no change. Body weight decreased with K (-0.5 kg) and increased with M (+ 0.4 kg). No important hematological or biochemical changes were seen with either drug. Slightly fewer patients reported adverse reactions during K monotherapy (40%) than with M (45%). In the latter group mainly central side effects were observed. The data confirm K to be an effective first-line antihypertensive agent with a favorable side-effect profile.

Blood Pressure↗
PubMed1983

Intravenous feeding in hepatectomized patients.

Ten patients, undergone major hepatic resections, treated with parenteral hyperalimentation in the postoperative period, were studied. Considered parameters were: free plasma amino acid levels and daily nitrogen balance. By comparing the trends of parameters under study with a group of patients, also hepatectomized but not treated with T.P.N., the importance of a high energetic and plastic post-operative intake is outlined. T.P.N. following major hepatic surgery appears particularly useful when the quality of the exogenous Nitrogen intake is carefully selected.

Adult↗