Biomedical subjects

L Vitali

Publications and source records attributed to L Vitali.

At least 19 recordsLinked to original sources

PubMed2006

Local pressure-induced metallization of a semiconducting carbon nanotube in a crossed junction.

The electronic and vibrational density of states of a semiconducting carbon nanotube in a crossed junction was investigated by elastic and inelastic scanning tunneling spectroscopy. The strong radial compression of the nanotube at the junction induces local metallization spatially confined to a few nanometers. The local electronic modifications are correlated with the observed changes in the radial breathing and G band phonon modes, which react very sensitively to local mechanical deformation. In addition, the experiments reveal the crucial contribution of the image charges to the contact potential at nanotube-metal interfaces.

Journal Article↗

PubMed2005

Kondo effect of molecular complexes at surfaces: ligand control of the local spin coupling.

The spin state of single magnetic atoms and molecules at surfaces is of fundamental interest and may play an important role in future atomic-scale technologies. We demonstrate the ability to tune the coupling between the spin of individual cobalt adatoms with their surroundings by controlled attachment of molecular ligands. The strength of the coupling is determined via the Kondo resonance by low-temperature scanning tunneling spectroscopy. Spatial Kondo resonance mapping is introduced as a novel imaging tool to localize spin centers in magnetic molecules with atomic precision.

Journal Article↗

PubMed2005

Insulin aspart improves meal time glycaemic control in patients with Type 2 diabetes: a randomized, stratified, double-blind and cross-over trial.

AIMS: This randomized, multi-centre, double-blind, stratified, two period, cross-over trial was undertaken to assess the pharmacokinetics and pharmacodynamics of insulin aspart injected immediately before compared with regular human insulin injected 30 min before a Mediterranean-style meal in 37 (23 M, 14 F) patients with Type 2 diabetes. METHODS: Insulin aspart or regular human insulin was given subcutaneously (0.15 U/kg) in random sequence, using a double-dummy technique (at one visit: human regular insulin at t=-30 min and placebo at t=0; at the other visit: placebo at t=-30 min and aspart insulin at t=0). Serum glucose and insulin concentrations (15 points) were measured after each meal for 240 min. RESULTS: Post-prandial glycaemic excursions were 20% lower with insulin aspart (IAsp) compared with regular human insulin (HI) treatment [ratio (Iasp/HI)=0.80, CI=(0.66-0.98), P=0.034]. The maximum serum glucose (SG) concentration was similar for the two treatments (P=NS). The (median) time to maximum SG was 25 min shorter for IAsp compared with HI (P=0.048). Maximum serum insulin concentration was higher after IAsp compared with HI (P=0.023) as well as the area under the 4-h serum insulin curve (P=0.006). Furthermore, the time to maximum serum insulin concentration was 27 min shorter after IAsp (P=0.039), even though IAsp was injected 30 min after HI. No adverse events occurred during the trial. CONCLUSIONS: In patients with Type 2 diabetes a more favourable insulin profile and a better glycaemic control were found with IAsp injected immediately before compared with HI injected 30 min before a Mediterranean-style meal.

Aged↗

PubMed2004

Kondo temperature of magnetic impurities at surfaces.

Based on the experimental observation that only the close vicinity of a magnetic impurity at metal surfaces determines its Kondo behavior, we introduce a simple model which explains the Kondo temperatures observed for cobalt adatoms at the (111) and (100) surfaces of Cu, Ag, and Au. Excellent agreement between the model and scanning tunneling spectroscopy experiments is demonstrated. The Kondo temperature is shown to depend on the occupation of the d level determined by the hybridization between the adatom and the substrate with a minimum around single occupancy.

Journal Article↗

PubMed2004

Phonon spectromicroscopy of carbon nanostructures with atomic resolution.

The vibrational properties of single-wall carbon nanotubes have been probed locally with atomic-scale resolution by inelastic electron tunneling spectroscopy with a low-temperature scanning tunneling microscope. The high spatial resolution has allowed the unraveling of changes in the local phonon spectrum related to topological defects. We demonstrated that the radial breathing mode is suppressed within tube segments of lengths below approximately 3 nm, and that in the cap region phonon modes characteristic of the fullerene hemisphere are emerging. Phonon spectromicroscopy should lead to a better understanding of the mechanisms that limit the transport of heat or electrical charge inside nanostructured carbon materials.

Journal Article↗

PubMed2001

Risk of type 1 diabetes development in children with incidental hyperglycemia: A multicenter Italian study.

OBJECTIVE: The aim of our study was to determine whether children with incidental hyperglycemia are at an increased risk of developing type 1 diabetes. RESEARCH DESIGN AND METHODS: A total of 748 subjects, 1-18 years of age (9.04 +/- 3.62, mean +/- SD), without family history of type 1 diabetes, without obesity, and not receiving drugs were studied and found to have incidental elevated glycemia defined as fasting plasma glucose >5.6 mmol/l confirmed on two occasions. Subjects were tested for immunological, metabolic, and immunogenetic markers. RESULTS: Islet cell antibodies >5 Juvenile Diabetes Foundation units were found in 10% of subjects, elevated insulin autoantibody levels in 4.6%, GAD antibody in 4.9%, and anti-tyrosine phosphatase-like protein autoantibodies in 3.9%. First-phase insulin response (FPIR) was <1st centile in 25.6% of subjects. The HLA-DR3/DR3 and HLA-DR4/other alleles were more frequent in hyperglycemic children than in normal control subjects (P = 0.012 and P = 0.005, respectively), and the HLA-DR other/other allele was less frequent than in normal control subjects (P = 0.000027). After a median follow-up of 42 months (range 1 month to 7 years), 16 (2.1%) subjects (11 males and 5 females), 4.1-13.9 years of age, became insulin dependent. All had one or more islet autoantibodies, and the majority had impaired insulin response and genetic susceptibility to type 1 diabetes. Diabetes symptoms were recorded in 11 patients and ketonuria only in 4 patients. The cumulative risk of type 1 diabetes was similar in males and females, and it was also similar in subjects under or over 10 years, whereas the cumulative risk of type 1 diabetes was increased in subjects with one or more autoantibodies and in those with FPIR <1st centile. CONCLUSIONS: Children with incidental hyperglycemia have a higher-than-normal frequency of immunological, metabolic, or genetic markers for type 1 diabetes and have an increased risk of developing type 1 diabetes.

Adolescent↗

PubMed2000

Serum liver enzymes in Turner syndrome.

UNLABELLED: Increased serum concentrations of liver enzymes are sometimes observed, in the absence of clinical symptoms of liver disease, in patients with Turner syndrome. The purpose of this study was to evaluate, in our Turner patients, serum liver enzyme levels and to find a cause for their increase. In 70 Turner patients, serum AST, ALT, GGT levels were evaluated every 6 months during a period of 0. 8-21.9 years. In patients in whom increased values of liver enzymes were found, serological markers for infectious hepatitis, serum hepatitis C virus RNA and virus genotype, IgG and IgA antibodies to gliadin and endomysium, coeruloplasmin, copper, alpha(1)-antitrypsin, total proteins and electrophoresis, IgG, IgA, IgM, fibrinogen, prothrombin, alkaline phosphatase, creatine kinase and total and direct bilirubin were also determined. Antinuclear, anti-smooth muscle and anti-liver-kidney microsome antibodies together with antithyroglobulin and anti-thyroid peroxidase antibodies were determined in all patients and in 166 age-matched female controls. In 22 patients, increased liver enzymes were observed, not related to karyotype. Follow-up showed that the hepatic disorder did not worsen with the time. Serological markers of hepatitis C virus were positive in three patients. When the serum liver enzyme increase was first observed in the other 19 patients with high enzyme levels (group A), 14 patients had never been submitted to hormonal treatment, 4 were on oestrogen/gestagen treatment and 1 was being treated with both growth hormone and oestrogen. Coeliac disease, alpha(1)-antitrypsin deficiency and Wilson disease were ruled out by appropriate investigations. In 8/19 group A patients, antinuclear and/or anti-smooth muscle antibodies were present versus 6/48 of patients with normal liver enzymes (group B). Thyroid antibodies were found in 8/19 patients in group A and in 13/48 in group B. Weight excess SDS was significantly higher in Turner girls with liver enzyme increase. Ultrasonography, performed in 17 patients of group A, showed mild hepatomegaly in 4 and increased echogenicity with fatty infiltration in 6. CONCLUSION: Hepatic abnormalities in Turner syndrome are not progressive. Oestrogen should not be considered the main cause of increased liver enzymes in Turner syndrome since most of our patients with this finding had not been previously treated with oestrogens. An auto-immune pathogenesis might be considered in some cases, whereas the association with weight excess seems the most frequent cause of liver disorder in Turner syndrome.

Adolescent↗

PubMed2000

Low serum TNF-alpha levels in subjects at risk for type 1 diabetes.

OBJECTIVE: The aim of our study was to determine whether serum TNF-alpha levels in individuals at risk of developing type 1 diabetes, such as first-degree relatives of diabetic patients and children with incidental hyperglycemia, underwent alterations, and also to establish whether these levels might be used to identify individuals prior to insulin dependence. RESEARCH DESIGN AND METHOD: We studied 71 healthy first-degree relatives (FDR) of type 1 diabetic patients and 11 children with incidental hyperglycemia. We looked for immunogenetic (HLA class II serologic alleles and HLA-DQ alpha/beta genomic polymorphisms), immunologic (islet-cell and insulin autoantibodies) and metabolic (FPIR to IVGTT) markers of type 1 diabetic risk. Serum concentrations of TNF-alpha were quantified using IRMA. RESULTS: We found significantly lower serum TNF-alpha levels in FDR of type 1 diabetic patients (median: 54.3 pg/ml) (p=0.01) and in children with incidental hyperglycemia (median: 10.83 pg/ml) (p<0.0001) compared to controls (median: 76.56 pg/ml). No significant difference was observed between subjects with or without immunogenetic, immunologic and metabolic markers of type 1 diabetic risk. A negative correlation was found between serum TNF-alpha and HbA1c levels (r=-0.27, p=0.023). Two children with incidental hyperglycemia, whose TNF-alpha levels were very low, developed type 1 diabetes 6 and 8 months after this study. CONCLUSION: Our results are compatible with an impaired immune system in the prediabetic period and suggest that serum TNF-alpha concentrations may be considered as an immunological marker useful to identify subjects at risk of developing type 1 diabetes.

Alleles↗

PubMed2000

[State of the art: low-molecular-weight heparin and beyond].

Approximately 20 years ago a new family of antithrombotic compounds started to be investigated: the low-molecular weight heparins (LMWH). The rationale for their use was based on the evidence that the inhibition of the Factor Xa of blood coagulation was less marked than that of Factor IIa when using the LMWHs as compared to unfractioned heparin (HF). This particular mechanism of action was considered to be of advantage regarding the safety profile (the pro-haemorrhagic effect) compared to HF. Today we know that the real advantage of LMWHs is due to their high bioavailability which makes safe and reliable their subcutaneous administration without laboratory monitoring. The LMWHs are equally effective than HF for the treatment of acute Deep Vein Thrombosis. For the prophylaxis of Venous Thromboembolism, LMWHs are indicated as first choice in high-risk patients such as those undergoing major orthopaedic surgery. The future development of this family of drugs encompasses the launch of the pentasaccharide which is a pure anti-/Xa inhibitor.

Anticoagulants↗

PubMed1999

Parental segregation of autoimmunity in patients with Turner's syndrome: preferential paternal transmission?

The prevalence of autoantibodies has been reported to be increased in both patients with Turner's syndrome and their parents. We evaluated organ-specific and non-organ-specific autoantibodies in 95 patients, ranging in age from infancy to adulthood, and in most of their parents, in order to determine the characteristics of autoimmune disorders in these families and to relate it to the genetic markers usually involved in autoimmunity (HLA, GM and KM genes). A statistically significant difference was observed between Turner patients and controls in the frequencies of organ-specific autoantibodies, in particular thyroid microsomal antibodies and thyroglobulin antibodies; however, the presence of autoantibodies was not associated with overt diseases in most cases. No significant difference was found between parents and controls. A study of the inheritance of the autoimmunity showed that transmission was preferentially paternal, since Turner patients had more chance of presenting autoantibodies when their fathers had autoantibodies rather than their mothers. A positive association was found between the presence of auto-antibodies and HLA-DR7;DQ2 and HLA-DR7;DQ9 haplotypes in Turner patients and fathers. No significant association was found between GM and KM allotype frequencies in Turner patients and their parents and the presence of autoantibodies. No epistatic interaction was demonstrated between HLA and GM or KM genes. Familial segregation was studied and a preferentially paternal transmission of HLA-DR7-carrying haplotypes and possibly also of the KM (1) allotype with autoimmunity was observed.

Adult↗

PubMed1998

Enhancement of soluble CD23 serum levels and cell-surface CD23-expression in subjects at increased risk of type 1 diabetes mellitus and in diabetic patients.

The low affinity receptor for IgE, CD23, is expressed on lymphocytes among other cell types. The purpose of the present study was to assess serum sCD23 levels and CD23 expression on peripheral blood mononuclear cells (PBMC) in people at increased risk of developing Type 1 diabetes mellitus and in diabetic patients. Serum sCD23 levels were significantly higher in first-degree relatives of Type 1 patients (median: 3.2 U ml(-1)) (p < 0.001) and in newly diagnosed (median: 3.3 U ml(-1)) (p < 0.001) and long-standing (median: 2.5 U ml(-1)) (p = 0.01) Type 1 diabetic patients than in controls (median: 1.2 U ml(-1)). Newly diagnosed patients showed higher levels than those with long-standing disease (p = 0.026). Moreover the percentage of B cells expressing CD23 were significantly higher in first-degree relatives (median: 48.6%) (p < 0.001) and in newly diagnosed (median: 58%) (p < 0.001) and long-standing (median: 44.8%) (p = 0.03) Type 1 diabetic patients than in controls (median: 28.5%). The increased sCD23 levels and the increased number of cells expressing CD23 observed in subjects at increased risk of Type 1 diabetes and diabetic patients may be indicators of Th2 activity in Type 1 diabetes.

Adolescent↗

PubMed1997

A 3-19-year follow-up study on diabetic retinopathy in patients diagnosed in childhood and treated with conventional therapy.

Few data are available from follow-up studies on diabetic retinopathy in patients diagnosed with insulin-dependent (Type 1) diabetes mellitus in childhood and treated with conventional therapy. We report the results of conventional insulin therapy on development of diabetic retinopathy in 100 children and adolescents (47 females and 53 males), aged 8.3 +/- 3.5 (1.2-16.4) years at diagnosis of disease. Oral or intravenous fluorescein angiography was performed during a 3-19 year follow-up in all patients. Retinopathy was staged according to the criteria of the Italian Society of Diabetology (SID). During follow-up, retinopathy was observed in 28 patients (28%). At the end of follow-up, retinopathy was present in 23 patients and had disappeared in 5. Life-table analysis showed a median disease-free interval of 10.8 years. At 10 years from diagnosis the percentage of patients free of retinopathy was 66%. Poor metabolic control, age, and degree of pubertal development at diagnosis were the most important risk factors.

Age Factors↗

PubMed1997

Celiac disease.

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Celiac Disease↗

PubMed1997

Rejection of islets differing by a single antigen is dependent on donor MHC.

To study the effect of expression of a single foreign antigen on the outcome of otherwise compatible mouse islet grafts, we have used transgenic mice expressing the human complement receptor 2 (CR2, CD21, C3d/EBV receptor) on their pancreatic beta-cells (RIP-CR2 mice). Donors were RIP-CR2 mice, typed at the major histocompatibility complex (MHC) as H-2(k), H-2(b), or H-2(bxk), and recipients were streptozotocin-treated nontransgenic B6 x CBA F1 mice (H-2(bxk)). H-2(b) or H-2(bxk) CR2-expressing islets were not rejected (mean survival time [MST] >100 days) but induced a peri-insulitis and an antibody response to CR2. In contrast, H-2(k) CR2-expressing islets were rejected in 80% of the cases with a MST of 65 +/- 23 days and were massively infiltrated by a destructive insulitis. In both cases, the infiltrate was mainly made of CD4+ cells, with few CD8+ cells. The isotype of IgG antibody response to CR2 was studied: recipients of H-2(k) grafts had a predominantly IgG1 response, while recipients of H-2(b) grafts had a balanced IgG2a and IgG1 response. To further evaluate the mechanism of differential rejection of the two types of grafts, recipients were immunized with CR2-expressing rat insulinoma cells before transplantation. Preimmunization with CR2 did not affect the outcome of H-2(b) grafts but greatly accelerated the rejection of H-2(k) grafts. These experiments indicate that expression of a single foreign antigen on beta-cells triggers an immune response leading to rejection or to peri-insulitis, depending on the MHC of donor islets.

Animals↗

PubMed1996

Clinical aspects of coeliac disease in children with insulin-dependent diabetes mellitus.

Coeliac disease (CD) is heterogeneous in its clinical presentation and pathological expression. Silent, latent and potential forms represent the submerged part of the so-called "coeliac iceberg". The association of insulin-dependent diabetes mellitus (IDDM) and CD has been widely reported. For the screening of CD in diabetic patients, anti-reticulin R1 (ARA-R1) and anti-endomysium (AEA) antibodies are more reliable markers than anti-gliadin (AGA) antibodies. Recent studies have reported an increased prevalence of CD in children with IDDM. In our experience intestinal biopsy confirmed a diagnosis of CD in 6 out of 172 diabetic patients, with a prevalence of 3.5%. Only occasionally does CD precede the onset of IDDM; more often CD is diagnosed shortly or sometimes years after the onset of diabetes. Typical gastrointestinal complaints of CD (such as diarrhoea, abdominal distension) are rare in IDDM patients, while atypical isolated signs or symptoms of CD are more common, in particular sideropenic anemia, short stature, delayed puberty, epilepsy, hypertransaminasemia, dyspeptic symptoms, herpetiform dermatitis, and recurrent aphthous stomatitis. It is recommended that all diabetic children, even those asymptomatic, should be screened yearly for CD, using a combination of AGA plus ARA-R1 and AEA.

Adolescent↗

PubMed1996

IDDM and autoimmune thyroid disease in the pediatric age group.

Diabetic patients have increased chances of developing autoimmune thyroid disease. Thyroid autoantibodies (Th-AAb) are more frequent in IDDM children than in the general population, ranging between 7 and 40%. As markers of thyroid autoimmunity, we assessed Th-AAb (MsA and TgA) cross-sectionally in 212 children and adolescents (93 girls and 119 boys) aged 1.2-21 years with IDDM from 0-18 years, and longitudinally in 90/212 (43 girls and 47 boys) at diagnosis and during a 3-10 year follow-up. In the cross-sectional study Th-AAb were found in 22/93 girls (23.7%) and 13/119 boys (10.9%). In the longitudinal study Th-AAb were observed at diagnosis in 6 patients, and during the follow-up in 9 girls. In 11/15 Th-AAb positive patients anti-nuclear antibodies were also present. Hormonal assessment revealed hypothyroidism in 3 girls (afterwards on replacement therapy), thyroid ultrasonography showed abnormal patterns in 5 girls, fine needle aspiration biopsy confirmed Hashimoto's thyroiditis in 9 (8 girls and 1 boy), with a higher frequency than that reported among healthy subjects (1-2%). Thyrotoxicosis also occurs with increased frequency in diabetic children than in the general population. We observed Graves' disease in only 1/212 IDDM patients, a 13 year-old boy in whom thyrotoxicosis developed 4 years after diabetes was diagnosed. The high prevalence of thyroid autoimmunity in our patients, particularly in females, suggests that diabetic children and adolescents should be screened for thyroid autoimmunity even if asymptomatic for hypo- or hyperthyroidism. Patients with IDDM and autoimmune thyroid disease should be evaluated for autoantibodies against other organs, such as adrenal glands and gastric mucosa. It is known that patients affected by type 1 (insulin-dependent) diabetes mellitus (IDDM) may have autoantibodies against different organs, such as thyroid, adrenal glands, gastric mucosa, parathyroid, with or without evident dysfunction of the target organ /1-8/. Among organ-specific disorders, autoimmune thyroid disease (ATD) is frequently associated with IDDM and the presence of thyroid autoantibodies (Th-AAb) has been considered a risk factor for the development of hypo- or hyperthyroidism /9/.

Adolescent↗

PubMed1995

Anticardiolipin antibodies in children and adolescents with insulin-dependent diabetes mellitus.

UNLABELLED: Anticardiolipin antibodies were determined in 29 diabetic children and adolescents, aged 3.9-26.8 years, with disease duration from 1 month to 19 years. Anti-islet cell antibodies (ICA-IgG and CF-ICA), anti-insulin antibodies (IAA), antithyroid antibodies and non organ-specific (NOSA) antibodies were also determined. Patients were grouped according to insulin-dependent diabetes mellitus (IDDM) duration: group I (n = 11) < 6 months, and group II (n = 18) > 5 years. Eleven of group II patients showed precocious signs of micro-angiopathic complications. Forty-two age- and sex-matched healthy subjects served as controls. IgG and IgM anticardiolipin antibodies were evaluated by ELISA and their results expressed as arbitrary units (AU). IgG anticardiolipin antibodies were found in 7 patients (24%), while IgM anticardiolipin antibodies were absent in all. IgG anticardiolipin antibodies were more frequent in IDDM patients than in controls (P < 0.005) and group I (in 6 out of 11 patients; 54.5%) than in group II (in 1 out of 18 patients; 5.5%) (P < 0.025). In five out of six group I patients with IgG anticardiolipin antibodies, ICA-IgG and/or CF-ICA were also found. No correlation was observed between anticardiolipin and other auto-antibodies, micro-angiopathic complications, and HLA typing. CONCLUSION: Anticardiolipin antibodies may reflect an abnormal immunological response in the early stage of diabetes mellitus and represent a transient auto-immune phenomenon.

Adolescent↗

PubMed1995

Organ- and non-organ-specific auto-antibodies in children with hypopituitarism on growth hormone therapy.

UNLABELLED: Serum non-organ-specific antibodies (NOSA) against nuclear, mitochondrial (AMA), smooth muscle, liver/kidney microsomal (LKM), reticulin, ribosomal, and organ-specific antibodies (OSA) against pituitary gland, gonads (testis, ovary) adrenal cortex, thyroid (thyroglobulin and microsomal), pancreas islet cells, gastric parietal cells and intestinal epithelial cells were evaluated in 45 patients with hypopituitarism (mean age 12.4 +/- 4.0 years). In 22 of them, 9 with isolated growth hormone (GH) deficiency (IGHD) and 13 with multiple pituitary hormone deficiency, MRI showed anterior pituitary hypoplasia with structural stalk abnormality and ectopic posterior pituitary. Twelve had isolated small anterior pituitary and IGHD and 11 had normal morphology of pituitary gland and IGHD. Controls were healthy age-sex-matched subjects. Thyroid antibodies were detected by a passive haemagglutination test while indirect immunofluorescence was used for the others. The auto-antibodies were found in 7/45 asymptomatic patients, a frequency not significantly different from that in controls; 5 were type NOSA and 2 type OSA. Pituitary antibodies were positive in 1 girl with IGHD and normal pituitary morphology. One girl developed hyperthyroidism during the follow up. Autoantibodies were equally distributed between the three groups and the frequency was not dissimilar from that in controls; this suggests that these patients are not at a higher risk of developing auto-immune disease, at least during the first two decades. CONCLUSION: Pituitary insufficiency in children with different MRI features seems unlikely to be secondary to an auto-immune process.

Adolescent↗