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M Novelli

Publications and source records attributed to M Novelli.

At least 19 recordsLinked to original sources
PubMed2006

Diagnosing pancreatic cancer: the role of percutaneous biopsy and CT.

AIMS: To determine the sensitivity and complications of percutaneous biopsy of pancreatic masses, and whether typical computed tomography (CT) features of adenocarcinoma can reliably predict this diagnosis. MATERIALS AND METHODS: A 5 year retrospective analysis of percutaneous core biopsies of pancreatic masses and their CT features was undertaken. Data were retrieved from surgical/pathology databases; medical records and CT reports and images. RESULTS: Three hundred and three patients underwent 372 biopsies; 56 of 87 patients had repeat biopsies. Malignancy was diagnosed in 276 patients, with ductal adenocarcinoma in 259 (85%). Final sensitivity of percutaneous biopsy for diagnosing pancreatic neoplasms was 90%; for repeat biopsy it was 87%. Complications occurred in 17 (4.6%) patients, in three of whom the complications were major (1%): one abscess, one duodenal perforation, one large retroperitoneal bleed. CT features typical of ductal adenocarcinoma were: hypovascular pancreatic mass with bile and/or pancreatic duct dilatation. Atypical CT features were: isodense or hypervascular mass, calcification, non-dilated ducts, cystic change, and extensive lymphadenopathy. Defining typical CT features of adenocarcinoma as true-positives, CT had a sensitivity of 68%, specificity of 95%, positive predictive value (PPV) of 98%, and negative predictive value of 41% for diagnosing pancreatic adenocarcinoma. CONCLUSION: Final sensitivity of percutaneous biopsy for establishing the diagnosis was 90%. CT features typical of pancreatic adenocarcinoma had high specificity and PPV. On some occasions, especially in frail patients with co-morbidity, it might be reasonable to assume a diagnosis of pancreatic cancer if CT features are typical, and biopsy only if CT shows atypical features.

Adenocarcinoma↗
PubMed2006

Azinphos methyl residues in shallow groundwater from the fruit production region of northern Patagonia, Argentina.

Groundwater samples were collected from monitoring wells along an area of intensive fruit production. Different types of correlations were investigated between soil physicochemical characteristics, depths and agricultural practices with pesticide detection frequency. In the three analyzed periods azinphos methyl, S-(3,4-diydro-4-oxobenzo[d]-[1,2,3]-triazin-3-ylmethyl)-O,O-dimethyl phosphorodithioate, showed a definite seasonal behavior related to the application pattern, increasing its concentration in the aquifer from October to November-December and then decreasing towards March. Samples obtained during the non-spraying season showed that azinphos methyl residues were lower than detection limit (LOD). An inverse correlation was observed between azinphos methyl concentration and the time elapsed since the last pesticide application. Seasonal events such as rain and irrigation influence the chemical concentration in the well, while no correlation was obtained between soil characteristics and azinphos methyl concentration. The soil attenuation capacity was not enough to prevent the presence of azinphos methyl in the aquifer during the application season.

Argentina↗
PubMed2005

T-cell receptor gamma gene rearrangement by multiplex polymerase chain reaction/heteroduplex analysis in patients with cutaneous T-cell lymphoma (mycosis fungoides/Sézary syndrome) and benign inflammatory disease: correlation with clinical, histological and immunophenotypical findings.

BACKGROUND: A dominant T-cell clone can be detected by polymerase chain reaction (PCR) in 40-90% of cutaneous samples from patients with cutaneous T-cell lymphoma (CTCL). MATERIALS AND METHODS: From 1996 to 2003 we analysed 547 cutaneous biopsies performed to exclude CTCL (mycosis fungoides, MF/Sézary syndrome, SS). The final diagnosis was benign inflammatory disease (BID) in 353 samples (64.5%) and CTCL in 194 (35.5%). T-cell receptor (TCR)-gamma gene rearrangement was studied by using a multiplex PCR/heteroduplex (HD) analysis. The PCR results were correlated with the clinical picture, the histological pattern and the presence of T-cell lineage antigen loss, using univariate and multivariate logistic regression analyses. OBJECTIVE: To determine the sensitivity and specificity of the multiplex PCR/HD analysis and to identify which are the clinical, histopathological or immunophenotypical features significantly associated with a positive T-cell clonality. RESULTS: A clonality was demonstrated in 83.5% of CTCL and in 2.3% of BID (P < 0.001). A significantly higher percentage of clonal cases was associated with the cutaneous T-score (71.4% in T1, 76.1% in T2 and 100% in nodular and erythrodermic MF samples) and with the presence of a T-cell lineage antigen loss (93.9% vs. 77.4%). Moreover, clonality was closely related to an increase in the histopathological score (51.3% in the samples with a score < 5, compared with 92% in the lesions with > or = 5). No significant difference in the percentage of clonal cases was found between T1/T2 and T3/T4 lesions with a histopathological score > or = 5. The multivariate logistic regression showed that the density and extent of the cell infiltrate, the degree of epidermotropism and the presence of cytological atypia share an independent predictive value for clonality in T1/T2 samples, even if the highest odds ratios (3.6) were associated with the density of the cell infiltrate. The disease course of T1/T2 patients was analysed according to the PCR findings. All the PCR-negative patients showed a long-standing stable disease course; on the other hand, a disease progression occurred in 12/87 (13.8%) positive patients. CONCLUSIONS: The multiplex PCR/HD analysis is associated with a high diagnostic accuracy (92.7%) in CTCL patients. The finding of a clonal T-cell rearrangement is more closely associated with the histological pattern (in particular with the density and extent of the cell infiltrate) rather than with the MF cutaneous T-score or immunophenotype.

CD8-Positive T-Lymphocytes↗
PubMed2004

Alteration of beta-cell constitutive NO synthase activity is involved in the abnormal insulin response to arginine in a new rat model of type 2 diabetes.

We have previously obtained a new type 2 diabetic syndrome in adult rats given streptozotocin and nicotinamide, characterized by reduced beta-cell mass, partially preserved insulin response to glucose and tolbutamide and excessive responsiveness to arginine. We have also established that the neuronal isoform of constitutive NO synthase (nNOS) is expressed in beta-cells and modulates insulin secretion. In this study, we explored the kinetics of glucose- and arginine-stimulated insulin release in perifused isolated islets as well as the effect of N-omega-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, to get insight into the possible mechanisms responsible for the arginine hypersensitivity observed in vitro in this and other models of type 2 diabetes. A reduced first phase and a blunted second phase of insulin secretion were observed upon glucose stimulation of diabetic islets, confirming previous data in the isolated perfused rat pancreas. Exposure of diabetic islets to 10 mM arginine, in the presence of 2.8 mM glucose, elicited a remarkable monophasic increment in insulin release, which peaked at 639 +/- 31 pg/islet/min as compared to 49 +/- 18 pg/islet/min in control islets (P << 0.01). The addition of L-NAME to control islets markedly enhanced the insulin response to arginine, as expected from the documented inhibitory effect exerted by nNOS activity in normal beta-cells, whereas it did not further modify the insulin secretion in diabetic islets, thus implying the occurrence of a defective nNOS activity in these islets. A reduced expression of nNOS mRNA was found in the majority but not in all diabetic islet preparations and therefore cannot totally account for the absence of L-NAME effect, that might also be ascribed to post-transcriptional mechanisms impairing nNOS catalytic activity. In conclusion, our results provide for the first time evidence that functional abnormalities of type 2 experimental diabetes, such as the insulin hyper-responsiveness to arginine, could be due to an impairment of nNOS expression and/or activity in beta-cells.

Animals↗
PubMed2004

Calorie restriction counteracts the impairment of adipocyte insulin-stimulated lipogenesis in aging rats, but not that induced by dexamethasone treatment.

In order to detect metabolic derangements that could be implicated in the pathogenesis of age-related insulin resistance, insulin-stimulated lipogenesis was investigated in isolated adipocytes from 24-month-old Sprague-Dawley rats, and the protective influence of caloric restriction was assessed. For comparison, the effects of glucocorticoid administration, used as a pharmacological tool to alter insulin sensitivity, were also studied. Caloric restriction consisted in a 40% reduction of the daily food intake of controls starting at 3 months of age. Dexamethasone (0.13 mg/kg/day) was administered for 14 days prior to sacrifice to both ad libitum-fed and dietary-restricted aging rats. Three-month-old animals, treated or untreated with dexamethasone, served as young controls. The results showed a significant age-related decrease of insulin-stimulated lipogenesis, which was fully prevented by a lifelong regimen of dietary restriction. Dexamethasone treatment markedly reduced insulin-stimulated lipogenesis in adipocytes isolated from all groups of rats, including those submitted to calorie restriction. In conclusion, our data indicate that the mechanism by which aging alters adipose tissue insulin-induced lipogenesis is reversed by dietary intervention and appears to be different from that triggered by dexamethasone. This particular defect might contribute to an imbalance of fat distribution among tissues that could induce or aggravate peripheral insulin resistance in old age.

Adipocytes↗
PubMed2003

Effect of pesticide use in fruit production orchards on shallow ground water.

As a part of landscape-scale study, ground water samples were collected from 30 wells located in fruit production farms belonging to the valley of Neuquen river during the period 1995-1998 and analyzed for organophosphate pesticides. As a consequence of the leaching process, ground water from the Valley of Neuquen River frequently contained concentrations of organophosphorus pesticides that exceeded acute toxicity risk ratios established to protect aquatic life. It was found that some pesticides, as azinphos methyl, had a high detection frequency, 66% of the samples, with concentrations varying from no detection to 48.9 ppb. Dimethoate, metidathion and phosmet were also detected with frequencies of 14.1, 13.6 and 10.8% and with concentration ranks from no detection to a maximum value of 10.9, 2.0 and 15.5 ppb, respectively. Seasonal variations and temporal trends were found for these compounds in ground water.

Argentina↗
PubMed2003

In vivo imaging of cellular proliferation in colorectal cancer using positron emission tomography.

BACKGROUND: and aims: Positron emission tomography (PET) using (18)F labelled 2-fluoro-2-deoxy-D-glucose ((18)FDG) is an established imaging tool, although the recent development of a biologically stable thymidine analogue [18F] 3'-deoxy-3-fluorothymidine ((18)FLT) has allowed PET to image cellular proliferation by utilising the salvage pathway of DNA synthesis. In this study, we have compared uptake of (18)FLT and (18)FDG with MIB-1 immunohistochemistry to evaluate the role of PET in quantifying in vivo cellular proliferation in colorectal cancer (CRC). PATIENTS AND METHODS: Patients with resectable, primary, or recurrent CRC were prospectively studied. Thirteen lesions from 10 patients (five males, five females), median age 68 years (range 54-87), were evaluated. Patients underwent (18)FDG and (18)FLT PET scanning. Tracer uptake within lesions was quantified using standardised uptake values (SUVs). Histopathological examination and MIB-1 immunohistochemistry were performed on all lesions, and proliferation quantified by calculating a labelling index (% of MIB-1 positively stained nuclei within 1500 tumour cells). RESULTS: Histology confirmed adenocarcinoma in 12 of 13 lesions; the remaining lesion was reactive. All eight extrahepatic lesions were visualised using both (18)FLT and (18)FDG. Three of the five resected liver metastases were also avid for (18)FLT and showed high proliferation, while the remaining two lesions which demonstrated no uptake of (18)FLT had correspondingly very low proliferation. There was a statistically significant positive correlation (r =0.8, p<0.01) between SUVs of the tumours visualised with (18)FLT and the corresponding MIB-1 labelling indices. No such correlation was demonstrated with (18)FDG avid lesions (r =0.4). CONCLUSIONS: (18)FLT PET correlates with cellular proliferation markers in both primary and metastatic CRC. This technique could provide a mechanism for in vivo grading of malignancy and early prediction of response to adjuvant chemotherapy.

Adenocarcinoma↗
PubMed2002

The antilipolytic agent 3,5-dimethylpyrazole inhibits insulin release in response to both nutrient secretagogues and cyclic adenosine monophosphate agonists in isolated rat islets.

This study intended to test the hypothesis that intracellular lipolysis in the pancreatic beta cells is implicated in the regulation of insulin secretion stimulated by nutrient secretagogues or cyclic adenosine monophosphate (cAMP) agonists. Indeed, although lipid signaling molecules were repeatedly reported to influence beta-cell function, the contribution of intracellular triglycerides to the generation of these molecules has remained elusive. Thus, we have studied insulin secretion of isolated rat pancreatic islets in response to various secretagogues in the presence or absence of 3,5-dimethylpyrazole (DMP), a water-soluble and highly effective antilipolytic agent, as previously shown in vivo. In vitro exposure of islets to DMP resulted in an inhibition (by approximately 50%) of the insulin release stimulated not only by high glucose, but also by another nutrient secretagogue, 2-ketoisocaproate, as well as the cAMP agonists 3-isobutyl-1-methylxanthine and glucagon. The inhibitory effect of DMP, which was not due to alteration of islet glucose oxidation, could be reversed upon addition of sn-1,2-dioctanoylglycerol, a synthetic diglyceride, which activates protein kinase C. The results provide direct pharmacologic evidence supporting the concept that endogenous beta-cell lipolysis plays an important role in the generation of lipid signaling molecules involved in the control of insulin secretion in response to both fuel stimuli and cAMP agonists.

1-Methyl-3-isobutylxanthine↗
PubMed2001

Metabolic and functional studies on isolated islets in a new rat model of type 2 diabetes.

In a new experimental type 2 diabetic syndrome, a 40% reduction of pancreatic beta cells was observed by morphometric analysis. In diabetic islets, as compared to control islets, insulin release was decreased in response to high glucose but not to other stimuli, and total glucose oxidation and utilization were unchanged or slightly reduced. The extent of metabolic and functional impairment appeared proportional to the beta-cell loss. However, a substantial decrease was found in protein level and activity (by 77 and 60%, respectively, versus controls) of mitochondrial FAD-glycerophosphate dehydrogenase (mGDH), the key enzyme of the glycerophosphate shuttle. Interestingly, in diabetic islets, as recently reported for mGDH-deficient transgenic mice, definite functional alterations (mainly in response to D-glyceraldehyde) were only obtained upon pharmacological blockade of the second shuttle (i.e. malate-aspartate) responsible for mitochondrial transfer of reducing equivalents. In conclusion, in this diabetes model with reduction of beta-cell mass, the islets, despite decreased mGDH amount and activity, appear metabolically and functionally active in vitro, likely through the intervention of adaptive mechanisms, yet prone to failure in challenging situations.

Aminooxyacetic Acid↗
PubMed2001

CD45RA+ immunophenotype in mycosis fungoides: clinical, histological and immunophenotypical features in 22 patients.

BACKGROUND: Mycosis fungoides (MF) is a cutaneous T-cell lymphoma (CTCL) usually characterized by a T-helper memory phenotype (CD3+, CD4+, CD8-, CD45R0+). Aberrant phenotypes are more commonly seen in the tumor stages. CD45RA expression has so far been documented in only a few cases of CD8+ or TCR gamma delta+ CTCL and in some pagetoid reticulosis cases. METHODS: Two hundred and fifteen MF patients were immunophenotyped in our laboratory between January 1992 and June 2000 and 22 cases of CD45RA+ MF (8.7%) were identified by immunohistochemical analysis. RESULTS: The majority of these CD45RA+ patients (20/22) showed a patch-plaque stage disease and an indolent clinical course, as expected in early-stage MF. The remaining 2 patients presented with stage IIB and IVA MF, and were characterized by an aggressive clinical course, with systemic spread. The immunohistochemical analysis revealed that CD45RA+ neoplastic cells belonged to the memory compartment, displaying a CD62L-, CD11a+, CD29+ phenotype. Most patients showed aberrant phenotypes, with a loss of T-cell lineage markers and expression of cytotoxic molecules or gamma-delta chain of the T-cell receptor. CONCLUSIONS: Our data show that CD45RA+ MF is a rare variant of CTCL and shares with the classic MF cases both the clinical features and disease course, even if it is characterized by a higher incidence of immunopathological abnormalities.

Adult↗
PubMed2001

The relevance of the CD4+ CD26- subset in the identification of circulating Sézary cells.

BACKGROUND: The lack of specific markers for the phenotyping of circulating neoplastic T cells in Sézary syndrome (SS) patients makes it difficult both to ascertain the presence of clonal cells and to quantify the tumour burden in the peripheral blood. In previous reports we showed that the lack of CD26 (dipeptidyl-aminopeptidase IV) is a characteristic feature of circulating Sézary cells (SC). OBJECTIVES: The purpose of this study was to ascertain, by means of high-resolution two-, three- or four-parameter flow cytometry, the relationship between CD26 expression on peripheral blood lymphocytes and peripheral blood involvement in cutaneous T-cell lymphoma patients and to assess its significance in SS diagnosis. METHODS: The patient population included 52 SS patients, 151 mycosis fungoides (MF) patients at different clinical stages (including 14 with blood involvement, B1-MF), 88 patients with erythrodermic inflammatory skin diseases (EISD) and 72 healthy donors (HD). CD26+ values were available in all cases, whereas CD4+ CD26- level measurement was performed in 23 SS, 141 MF, 71 EISD and 72 HD. RESULTS: CD4+ CD26- percentage values were higher than 30% in all but one B1-MF and higher than 40% in all SS cases, whereas HD, EISD and B0-MF patient values were always lower than 30%. A statistically significant difference was found in both CD26- and CD4+ CD26- percentage and absolute values between SS and HD, EISD and B0-MF patients. The CD26- and CD4+ CD26- percentage values (but not the absolute values) were significantly higher in B1-MF compared with HD, EISD and B0-MF patients (P < 0.001). Moreover, CD26- absolute values and CD4+ CD26- percentage and absolute values were significantly higher in SS than in B1-MF (P < 0.001). A statistically significant direct relationship was found between CD4+ CD26- percentage values and the percentage of circulating SC within the lymphoid population in SS and B1-MF (r = 0.77; P < 0.001). The lack of CD26 was confirmed on phenotypically clonal cells in patients with an expanded circulating TCRvbeta population or a T-cell antigen loss. Sorted CD4+ CD26- cells from both SS patients and HD showed the characteristic cerebriform nuclei of SC. CONCLUSIONS: We feel that a CD4+ CD26- percentage value higher than 30% of peripheral blood lymphocytes could correctly identify the presence of peripheral blood involvement in SS and MF patients.

Adult↗
PubMed2001

Dexamethasone-induced insulin resistance and pancreatic adaptive response in aging rats are not modified by oral vanadyl sulfate treatment.

OBJECTIVE: To explore the adaptive response of the endocrine pancreas in vivo and in vitro and the possible beneficial effect of the insulino-mimetic agent vanadyl sulfate (VOSO(4)), using glucocorticoid treatment to increase insulin resistance, in aging rats. DESIGN AND METHODS: Dexamethasone (Dex) (0.13 mg/kg b.w.) was administered daily for 13 days to 3- and 18-month old Sprague-Dawley rats and oral VOSO(4) was given from the 5th day. Plasma glucose, insulin and free fatty acids (FFA) concentrations were measured during these treatments and the insulin secretory response of the isolated perfused pancreas was assessed at the end of the experiment. RESULTS AND CONCLUSIONS: In both young and aging rats, particularly in the latter, hyperinsulinemia and increased in vitro insulin responsiveness to glucose were observed in response to Dex treatment, concomitant with an increase in plasma FFA concentrations. Thus, in glucocorticoid-treated animals, the beta-cell adaptive response occurred in both age groups and could possibly be mediated by increased circulating FFA; however, it was insufficient to prevent hyperglycemia in 60% of aging animals. Oral VOSO(4) administration failed to correct Dex-induced alterations in glucose and lipid metabolism, although it influenced in vitro beta-cell responsiveness to stimuli in aging rats.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Isolated liver transplant and sequential small bowel transplantation for intestinal failure and related liver disease in children.

Liver dysfunction is a well-recognized complication of intestinal failure in children. Advances in total parenteral nutrition (TPN) have allowed these children to survive while their intestinal tract gradually adapts. Unfortunately TPN may lead to cholestatic liver disease particularly in the young children. Progression of liver disease is associated with a poor prognosis and is an indication for small bowel transplantation. We report our experience of orthotopic liver transplantation in four children with short gut and sequential liver and small bowel transplantation in one child. All children had TPN-related liver failure. Causes of intestinal failure included necrotising enterocolitis (n=2), gastroschisis (n=1), intestinal atresia (n=1), and megacystic, microcolon syndrome (n=1). At the time of liver transplantation the children's mean age was 10.9 months (2.5-24) and weight 6.7 kg (4.8-10.1). The mean serum bilirubin was 522 micromol/liter (299-823), aspartate transaminase 423 IU/liter (49-1024) and international normalized ratio 2.8 (2-3.9). There were two deaths both from respiratory failure secondary to adenovirus pneumonia including the child who received a sequential small bowel transplant. Three children with isolated liver grafts are alive and off TPN at 20 months (mean) follow up (range 6-35). Isolated orthotopic liver transplantation has a role in selected children with intestinal failure, particularly those with short but normally functioning gut and progressing with satisfactory intestinal adaptation but developing liver disease. Those children with TPN-related liver disease and unadapted gut or irreversible intestinal disease need combined liver and small bowel transplantation. Sequential small bowel transplantation is feasible after orthotopic liver transplantation and may provide an option for the child with terminal liver and small bowel failure.

Adolescent↗
PubMed2000

Effects of low-dose VOSO(4) on age-related changes in glucose homeostasis in rats.

The effects of low doses of vanadyl sulfate (0.2 mg/ml in the drinking water) on the age-related impairment of glucose homeostasis in Sprague-Dawley rats were investigated. VOSO(4) administration was initiated in 5-month-old animals and lasted 3 months. Thus, in 8-month-old rats, we investigated glucose metabolism in vivo and insulin secretory function in vitro. Results showed that VOSO(4) allowed the disposal of an oral glucose load at lower insulin levels than in age-matched controls. No significant changes were found in muscle glucose transporter (GLUT-4) levels or in glycogen content upon VOSO(4) treatment. Islets isolated from VOSO(4)-treated rats released less insulin than control islets, but showed a better preserved sensitivity to secretagogues, in terms of incremental release over basal release, secretory efficiency, and maintenance of the priming effect of glucose. In conclusion, chronic low-dose VOSO(4) treatment facilitates insulin action by a mechanism independent of muscle GLUT-4 levels and helps preserve the appropriate sensitivity of beta cells to stimuli, thereby preventing age-dependent functional alterations.

Aging↗
PubMed2000

Allelic loss at SMAD4 in polyps from juvenile polyposis patients and use of fluorescence in situ hybridization to demonstrate clonal origin of the epithelium.

Juvenile polyposis syndrome (JPS; Online Mendelian Inheritance in Man2 174900) is a rare Mendelian disorder in which individuals have typical hamartomatous polyps within the gastrointestinal tract. The stromal element of the polyps has classically been thought to be the proliferative component, although epithelial malignancies (largely gastrointestinal cancers) occur more frequently than expected in JPS patients. Germ-line mutations in SMAD4 (DPC4) account for about a third of JPS cases. It has been postulated that the apparent paradox of a stromal lesion predisposing to epithelial malignancy can be resolved by the "landscaper" effect: an abnormal stromal environment affects the development of adjacent epithelial cells, and the resulting regeneration of damaged epithelium leads to an increased risk of cancer. We have found allele loss at the SMAD4 locus on 18q in polyps from JPS individuals with a germ-line SMAD4 mutation, showing that SMAD4 is acting as a tumor suppressor gene in JPS polyps, as it does in sporadic cancers of the gastrointestinal tract. Interphase fluorescence in situ hybridization showed deletion of one copy of SMAD4 in the epithelial component of JPS polyps, but not in the inflammatory infiltrate. Fluorescence in situ hybridization also suggested that a single copy of SMAD4 was present in stromal fibroblasts of JPS polyps. Thus, biallelic inactivation of SMAD4 occurs in both the epithelium and some of the stromal cells in these lesions, suggesting a common clonal origin. Epithelial malignancies almost certainly develop in juvenile polyposis through direct malignant progression of the epithelial component of the hamartomas. SMAD4/DPC4 probably acts as a "gatekeeper" tumor suppressor in juvenile polyps, and there is no need to invoke a "landscaper hypothesis."

Adenomatous Polyposis Coli↗
PubMed2000

Age-dependent reduction in GLUT-2 levels is correlated with the impairment of the insulin secretory response in isolated islets of Sprague-Dawley rats.

In this study we have investigated the insulin secretory response to glucose and other secretagogues (2-ketoisocaproate, 3-isobutyl-1-methyl-xanthine and arginine) of pancreatic islets isolated from Sprague-Dawley rats of various ages (from 2 to 28 months). Our results showed a significant decline in the glucose-stimulated insulin secretion, starting at 12 months of age. On the other hand, the response to non-glucose secretagogues (and mainly to 2-ketoisocaproate) was less impaired with advancing age than that to glucose. We also observed a progressive age-related decline of protein levels of the glucose transporter GLUT-2 in pancreatic islets, which was temporally concomitant and quantitatively comparable with the beta-cell alteration in glucose responsiveness (-40/50%). Finally, we observed a significant increase of the islets insulin content in older rats with respect to younger animals. We conclude that in the islet of older rats the impaired capability to respond to glucose could be dependent, at least in part, on the age-dependent reduction in GLUT-2 and could be compensated by mechanisms including a preserved responsiveness to non-glucose secretagogues and/or the development of islet hypertrophy.

1-Methyl-3-isobutylxanthine↗