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F Dotta

Publications and source records attributed to F Dotta.

At least 55 records · Page 3Linked to original sources
PubMed1989

Ganglioside expression in human pancreatic islets.

Recent biochemical studies have shown that the cytoplasmic islet cell-antibody autoantigen has properties of a monosialoganglioside (GM). To characterize islet glycolipids and ascertain whether islets express unique gangliosides, we determined the pattern of ganglioside expression in whole human pancreas and isolated human islets using high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC). The major gangliosides detected in glycolipid extracts of whole human pancreas were GM3, GD3 (disialoganglioside), and in a lesser amount, a GD1a-comigrating ganglioside. In contrast to whole human pancreas, isolated human islets were found to predominantly express GM3, an acidic glycolipid comigrating with GM2, and a ganglioside with mobility between GM2 and GM1 by both HPLC and HPTLC. Quantitation of the major ganglioside UV peaks seen on HPLC gave the following results. In whole pancreas, GM3 represented 66.7% of total gangliosides detected; an asialoglycolipid comigrating with GM2, 2.0%; a ganglioside migrating between GM2 and GM1, 2.6%; GD3, 22.6%; and a GD1a-comigrating ganglioside, 6.1%. In isolated islets, these components were found at the following levels: GM3, 14.9%; GM2-comigrating glycolipid, 74.2%; a ganglioside migrating between GM2 and GM1, 9.8%; GD3, 1.1%; and the GD1a-comigrating ganglioside, not detectable.

Chromatography, High Pressure Liquid↗
PubMed1989

Modulation by sodium butyrate of the differentiated status of a clonal pancreatic B-cell line (RIN).

RINmRH cells are a cloned cell line derived from a transplantable rat insulinoma. These cells display only some of the differentiated structure/function features of native pancreatic B-cells. In particular, they do not efficiently or reproducibly express islet B-cell surface antigens, which would otherwise render them useful for screening for the presence of anti-islet cell surface antibodies in the serum of suspected diabetic patients or their relatives. This study examines whether sodium butyrate can enhance expression of B-cell differentiation antigens on RIN cells. RIN cells were exposed to 1,2 or 4 mM butyrate for nine days, and cell growth followed. At 1 mM, butyrate inhibited cell growth by 90%. At the higher concentrations, there was a net loss in the number of cells per culture dish. Exposing the cells to 1 mM or 2 mM butyrate for two days, resulted in a 50% increase in cellular insulin content at the expense of a partial (1 mM) or complete (2 mM) loss of stimulated insulin release in response to glyceraldehyde or serine. A concentration of 1 mM butyrate was therefore used for subsequent studies. The binding to RIN cells of a panel of monoclonal antibodies (mAb's) known to bind native islet cells (R2D6, A2B5, A1D2, 3G5) as well as of serum from a diabetic patient known to carry anti-islet cell antibodies, was screened by cytofluorography or by a radio-binding assay. The relative binding affinity of the mAb's was 3G5 greater than A1D2 greater than A2B5 greater than R2D6. Only 2-3% of the cells were bound by the diabetic patient serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Approach to the abdominal aorta: impairment of respiratory function after supraumbilical transverse and midline laparotomy.

Midline and transverse incision are commonly used in upper abdominal surgery. A comparison of the two procedures with respect to the respiratory function, assessed by spirometry, blood gas analysis, inspiratory and expiratory pressures, and thoraco-abdominal respiratory synchronism, was made in two groups of patients after surgery on the abdominal aorta. 32 patients affected by abdominal aortic obstructive or aneurysmatic disease, candidates for aortoiliac revascularization, were randomized into two groups of 17 (group A) and 15 (group B) patients respectively. Group A underwent midline laparotomy and group B supraumbilical transverse laparotomy. Ventilatory function and blood gas analysis were determined on the day before operation and on the second and eight postoperative day. All patients showed a depressed ventilatory function postoperatively, but the impairment was significantly minor after transverse laparotomy.

Adult↗
PubMed1988

A prozone phenomenon interferes in islet cell antibody detection: direct comparison of two methods in subjects at risk of diabetes and in insulin dependent diabetics at onset.

A recent international workshop documented marked interlaboratory variation in end point titers of standard islet cell antibody (ICA) positive sera. End titers were lower using a modified assay which utilizes fluorescein labeled protein A (ICA-pA) rather than fluoresceinated anti-IgG (ICA-IgG) to detect antibody binding to islets. In this study we sought to compare directly two ICA assays with respect to future development of IDDM. Sera were obtained from 26 prospectively evaluated high risk subjects identified by family screening or history of transient hyperglycemia and 12 normal controls. As expected, end point titers for ICA positive sera were 10 times greater using the ICA-IgG assay than with the ICA-pA assay. However, despite higher end point titers, the ICA-IgG assay failed to detect more 'prediabetics' and showed a prozone effect. Fourteen subjects were positive at a 1:2 dilution using the ICA-pA assay. Only 10 of these 14 were positive at a 1:2 dilution using the ICA-IgG assay but all became positive at greater sera dilutions. No normal controls were positive using either assay. A similar prozone was observed with anti-islet monoclonal antibodies A2B5 and 4F2. Sera from 14 long-standing IDDM patients (where titers of ICA may have decreased relative to time of onset of diabetes) which were negative using ICA-pA were also assayed using ICA-IgG. Five sera positive for ICA-IgG but negative for ICA-pA were identified. In addition two sera in which a prozone effect was seen with ICA-pA were identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination Tests↗
PubMed1988

A novel neuroendocrine cell surface glycoprotein: identification, isolation, and initial characterization.

Murine monoclonal antibodies (MAbs) HISL-5, -9, and -14, generated after immunization of mice with human pancreatic islet cell preparations, recognize a differentiation antigen expressed by the pancreatic islet cells. These MAbs react strongly with all endocrine cell subtypes of human pancreatic islets, but minimally if at all with the exocrine acinar cells, vascular cells, and stromal connective tissue cells of the pancreas. The antigen is located on the cell surface (plasma membranes), as indicated by immunofluorescence staining of viable cell preparations. Besides the pancreatic islets, HISL-5, -9, and -14 antigenic determinants are also expressed by thyroid follicular cells, parathyroid chief cells, and anterior pituitary cells, other commonly involved targets in organ-specific autoimmune disorders. Preliminary biochemical findings indicated that the MAb-defined epitope(s) is trypsin sensitive and resistant to periodate oxidation and exposure to chloroform-methanol. Further biochemical studies, including single step MAb immunoaffinity chromatographic purification, indicate that the antigen recognized by the MAbs HISL-5, -9, and -14 is a 100 K glycoprotein.

Animals↗
PubMed1988

Circulating anti-immunoglobulin antibodies in recent-onset type I diabetic patients.

Human sera from 51 recent-onset insulin-dependent (type I) diabetic patients and 47 unrelated control subjects were screened for the possible presence of circulating factors reacting with several anti-pancreatic islet monoclonal antibodies (MoAb.ISL) in solid-phase radioimmunoassay methods (the original goal being the detection of anti-idiotypic islet cell antibodies and/or specific islet cell antigen-bearing immune complexes). MoAbs from the parental myeloma cell line and purified immunoglobulins (Igs) from different animal species were controls. Type I diabetic sera showed significantly increased binding to MoAb.ISL-coated wells compared with normal subjects (P less than .001). However, the same sera also tended to show a higher binding to the control (non-islet-related) MoAb. Sera from type I diabetic patients also reacted with horse, bovine, pig, rabbit, and goat IgG. Displacement of the binding has been obtained by F(ab')2 and/or Fc fragments of IgG. Evidence has been obtained regarding a similar reaction with human IgM. All the sera were negative when tested for rheumatoid factor by nephelometry. The circulating antibodies described have been proven to be different from islet cell autoantibodies. An anti-Ig antibody is thus present in the sera of recent-onset diabetic patients and represents an additional immunological phenomenon with possible physiopathological and clinical significance.

Adult↗
PubMed1987

Immunology in diabetic pregnancy: activated T cells in diabetic mothers and neonates.

Lymphocytes bearing surface antigens indicating early and full activation have been evaluated, in addition to T cell subsets, in blood samples from diabetic pregnant patients, neonates from diabetic mothers and control groups. The type of diabetes and the trimester of pregnancy were taken into account. Monoclonal antibodies were used to enumerate total T cells, helper/inducer, cytotoxic/suppressor Tlymphocytes and activated mononuclear cells using antibodies binding lymphocyte surface antigens as markers of early lymphocyte activation, and MHC Class II surface antigens as markers of late activation. A decrease in T-helper cells during the third trimester of pregnancy in Type 1 (insulin-dependent) and gestational diabetic patients (p less than 0.02) and a decrease in T-suppressor cells in Type 2 (non-insulin-dependent) diabetic pregnant patients during the third trimester (p less than 0.01) were observed in relation to normal values. As in normal pregnancy, 4F2-positive cells were increased in 48% of diabetic pregnant patients during the second and third trimesters of gestation. Class II-positive cells were increased in almost 60% of Type 1 and gestational diabetic patients during the last trimester of pregnancy in comparison with normal pregnant women and control subjects. A decrease in T-helper cells (p less than 0.02) and a clear increase in 4F2-positive cells (p less than 0.001) and Class II-positive lymphocytes (p less than 0.005) were observed in the infants of diabetic mothers in comparison with control subjects. The maternal cellular immune system, actively altered in pregnancy, is fully activated in a number of Type 1 and gestational diabetic pregnant patients. Activated lymphocytes are even found in the neonates of diabetic mothers, but these do not trigger the events leading to the onset of diabetes in the short term.

Adult↗
PubMed1987

Humoral and cellular immune abnormalities in neonates of diabetic mothers: any pathological role?

Insulin antibodies, insulin complexes, T-cell subsets and T-cells bearing surface antigens indicating early activation were studied in 35 and 24 infants of diabetic and of normal mothers respectively, which were compared with normal adult control subjects. Anti-insulin antibodies were evaluated using a modified version of Andersen's method, insulin complexes were assessed by a method developed by us; total T cells, helper/inducer and cytotoxic/suppressor T lymphocytes, and early activated T lymphocytes were determined using the monoclonal antibodies OKT3, OKT4, OKT8 and 4F2 respectively. The presence of insulin antibodies was correlated to macrosomia, hypoglycaemia and respiratory distress syndrome. Insulin-anti-insulin complexes were found in some of the neonates and were likely to have been formed by maternal antibodies and insulin from the neonate. Modifications of T-cell subsets were found in the neonates both of diabetic and of normal mothers. --Despite the presence of these immune abnormalities in some infants of diabetic mothers, the clinical onset of diabetes was not diagnosed in any of the cases studied. Nevertheless, the immunological abnormalities in neonates of diabetic mothers have short-term pathogenetic effects which raises the question of their possible long-term effect.

Adult↗
PubMed1987

Expression of cytoplasmic islet cell antigens by rat pancreas.

A major problem in standardization of the islet cell cytoplasmic antibody (ICA) assay is variation in sensitivity of the different human pancreas substrates used in individual laboratories. To circumvent this problem, we have developed an assay that utilizes Wistar-Furth rat pancreas as substrate, an anti-islet monoclonal antibody (A2B5) to identify islets and fluorescein-conjugated protein A to identify patient autoantibodies. Sera from 85 control subjects, 27 type I diabetics, and 17 subjects at high risk for developing type I diabetes were assayed in parallel with our standard ICA assay on human pancreas substrate and with Wistar-Furth rat pancreas as substrate. Two sera from control subjects (2 of 85) were ICA positive with rat pancreas compared to 1 of 85 with human pancreas substrate. Sera from 11 of 27 type I diabetics and 15 of 17 sera from high-risk subjects were ICA positive with either rat or human pancreas substrate. A correlation between the specific islet fluorescence readings on human and rat pancreas sections was found with sera from high-risk and control subjects. Furthermore, end-point titers of an ICA-positive serum were identical with both assays. Finally, incubation of an ICA-positive serum with glycolipids, extracted from either human or Wistar-Furth rat pancreas, blocked subsequent ICA binding. These findings suggest that Wistar-Furth rat pancreas expresses an identical or similar autoantigen to human pancreas.

Adolescent↗
PubMed1986

Activated T cells in normal pregnant women and neonates.

The phenotyping of T-cell subsets and T cells at different stages of activation was performed using a panel of monoclonal antibodies in samples from normal pregnant women at different stages of gestation and in the cord blood of neonates. The data obtained from pregnant women showed a slight decrease in the total number of T cells at the beginning of pregnancy, whereas there was a clear increase in 4F2-positive lymphocytes after a few months of gestation. No significant increase in Class II-positive lymphocytes was observed in normal pregnant women in comparison with adult healthy women. The data from neonates revealed a clear decrease of OKT3- and OKT4-positive cells and an increase of 4F2-positive cells in comparison with control subjects. These data indicate that alerted, but not fully activated, lymphocytes are present in the circulation of both the mother, after the first months of pregnancy, and the neonate. This finding reinforces the concept that during pregnancy there is an activation of certain immune components rather than a general depression of the immune system.

Adult↗
PubMed1983

The autonomic innervation of the human greater saphenous vein.

The existence of a double catecholaminergic and cholinergic innervation was demonstrated in the human greater saphenous vein. Catecholamine-containing nerve fibres are organized in a network-like plexus localized at the adventitial-medial border. Acetylcholinesterase-containing nerve fibres are arranged in a plexus found at the adventitial-medial border as well. Catecholamine and acetylcholinesterase-containing nerve fibres, while localized in close apposition since they occupy the same portion of the vein, represent two distinct and independent populations of nerve fibres coming likely from the sympathetic and parasympathetic sections of the autonomic nervous system respectively. Our findings demonstrating a close relationship between catecholaminergic and cholinergic nerve fibres within the wall of the human greater saphenous vein offer morphological support to physiological and pharmacological results reported in the literature of a presynaptic control exerted by cholinergic nerves on norepinephrine release at the level of the saphenous vein.

Acetylcholinesterase↗
PubMedDate not supplied

Autoantibody negative new onset type 1 diabetic patients lacking high risk HLA alleles in a caucasian population: are these type 1b diabetes cases?

BACKGROUND: In Caucasians, a small number of Type 1 diabetic patients do not show evidence of humoral islet autoimmunity at disease onset, at least with common screening procedures. In African- and Hispanic-American diabetic children at time of diagnosis, many show no evidence of autoimmunity but have an atypical clinical form of the disease. According to the recent American Diabetes Association classification, this subgroup of autoantibody negative patients is referred to as Type 1b diabetic subjects. In the present study, a homogeneous Caucasian Type 1 diabetic clinic-based cohort has been evaluated at diagnosis using a large panel of diabetes-related antibodies and then characterized for various genetic features in order to identify newly diagnosed Type 1 diabetics who are potentially autoantibody negative, i.e. possibly referrable to as idiopathic Type 1b diabetes. METHODS: Newly diagnosed Type 1 diabetic patients of Italian origin (n=141, mean age 12.0+/-7.6 years) were tested for anti-islet cell, anti-insulin, anti-65 kDa isoform of glutamic acid decarboxylase and anti-amino acid residues 256-979 of the tyrosine-phosphatase IA-2 molecule autoantibodies (Step 1). Only those patients found to be autoantibody negative were tested for anti-disialo-ganglioside GD3, anti-thyroid peroxidase, anti-thyroglobulin, anti-21-OH hydroxylase, anti-gastric parietal cell and anti-transglutaminase antibodies (Step 2). Sera negative for the presence of these six autoantibodies as well were characterized in terms of HLA DRB1, DQB1 and CTLA-4. RESULTS: Six out of 141 subjects (3.5%) were autoantibody negative in the first step of the study and five out of six in the second. These five autoantibody negative patients underwent genetic analysis. Three of them had at least one Type 1 diabetes-related high risk HLA haplotype (3/141, 2.1%) while the remaining two cases showed neutral (DR5-DQB1*0301/DR5-DQB1*0301) or strongly protective (DR2-DQB1*0602/DR2-DQB1*0602) HLA genotypes, respectively (2/141, 1. 4%). CONCLUSIONS: Clinically defined Type 1 diabetic patients with no sign of autoimmunity do exist in a Caucasian population. These patients (2 out of 141) that cannot be classified as Type 1a diabetic patients lack clinical characteristics of Type 1b diabetes and have to be reconsidered for a more appropriate ADA classification. These data suggest the need of further large population-based studies to understand if Type 1b diabetes really occurs in a Caucasian population. The patient with a strongly protective HLA genotype is particularly interesting considering that among Caucasians only a few sporadic cases with Type 1 diabetes and DQB1*0602, have been reported, none of whom was homozygous at DQB1 locus.

Abatacept↗
PubMedDate not supplied

Effects of prolonged exposure to pancreatic glucagon on the function, antigenicity and survival of isolated human islets.

BACKGROUND: Certain clinical conditions are associated with inappropriately high levels of circulating glucagon. To date, little information is available about the direct effects of prolonged exposure of human islet cells to pancreatic glucagon. In the present study we evaluated the function, antigenicity and survival of human islets exposed for 24 h to human pancreatic glucagon. METHODS: We prepared human islets of Langerhans by collagenase digestion and density-gradient purification, incubated them for 24 h with 44 or 430 pmol/l pancreatic glucagon at physiological (5.5 mmol/l) glucose level, and evaluated their insulin release function, which was then compared with that obtained from islets kept at high (11.1 mmol/l) glucose concentration. In addition, aliquots of the islets were evaluated to assess their chemotactic properties towards human monocyte-macrophage cells, and their potency to induce cytokine release from human lymphocytes. Finally, survival of the islet cells cultured under varying conditions was evaluated, and an assessment was performed of mRNA expression of Bcl-2 and Bax proteins. RESULTS: The insulin secretion results demonstrated that, compared to the control islets, the islets previously exposed to either 44 or 430 pmol/l glucagon exhibited changes in insulin release in response to glucose, consisting of augmented secretion at low glucose challenge, and no further significant increase at high glucose stimulation, similar to the effects observed with islets pre-cultured with high glucose. These effects were reversible, as documented by the recovery of normal islet sensitivity to glucose after an additional 24-h culture in medium lacking glucagon. Compared to control islets, the culture medium from islets pre-cultured with high glucagon or high glucose showed an increased chemotactic potency towards human monocyte-macrophage cells. In addition, human lymphocytes released a greater amount of tumour necrosis factor alpha when co-cultured with the islets pre-exposed to high glucagon or high glucose, whereas no significant difference was observed (in comparison with control islets) as regards the release of gamma-interferon, interleukin-2 and interleukin-10. The TUNEL technique and RT-PCR showed, respectively, no major difference in cell survival and expression of mRNA encoding for Bcl-2 and Bax protein between control islets and islets kept for 24 h in the presence of high glucagon or high glucose. CONCLUSIONS: Our results show that in vitro exposure of human islets to pancreatic glucagon for 24 h causes changes in the function and antigenicity of isolated human islets that are similar to the changes observed after pre-culture with increased glucose levels. Under our experimental conditions, these changes were not accompanied by any evidence of cytotoxicity.

Cell Survival↗