Glucagon gene regulatory region directs oncoprotein expression to neurons and pancreatic alpha cells

The regulatory region of the rat preproglucagon gene targets expression of the SV40 large T oncoprotein to two cell types in transgenic mice, the pancreatic alpha cells and a set of neurons localized in the hindbrain, both of which normally produce preproglucagon. Additional neurons in the forebrain and midbrain stain for T antigen but do not express the endogenous glucagon gene. Synthesis of T antigen in endocrine alpha cells results in the heritable development of pancreatic glucagonomas. In brains of transgenic mice from three independent lineages, expression of the hybrid gene begins at embryonic day 12 in neuroblasts of the hindbrain, where it continues throughout adult life, most notably in the medulla. Remarkably, oncoprotein expression in both proliferating neuroblasts and mature neurons has no apparent consequences, either phenotypic or tumorigenic. Expression of the hybrid glucagon gene in both neurons and islet cells supports a possible interrelationship between these cell types.

Modification of enzymatic antioxidants in retinal microvascular cells by glucose or advanced glycation end products

Oxidative stress is one possible pathogenic mechanism to explain diabetic microangiopathy. In the present study, we determined the antioxidant enzyme activities in bovine retinal microvessels and cultured retinal microvascular cells: endothelial cells (BREC) and pericytes (BRP). We further investigated the effects of high glucose and advanced glycation end products (AGE) on these enzyme activities in BREC and BRP. Antioxidant enzyme activities in native retinal microvessels and BREC were quite similar but differed markedly from the BRP ones. High glucose decreased Se-GPx activity (about 20%) in BREC compared to mannitol. High concentrations of mannitol or NaCl increased Se-GPx activity (up to 40%) compared to control medium, suggesting that hyperosmolarity could regulate Se-GPx in BREC. No changes in antioxidant enzyme activities were observed when BRP were cultured with glucose or mannitol at high concentrations. AGE-BSA had no effect on enzyme activities in BREC, whereas 20 microM AGE-BSA increased catalase (40%) and superoxide dismutase (60%) activities in BRP. Differences in antioxidant enzyme activities observed between BREC and BRP, cultured with high concentrations of glucose or AGE, might help to explain their different behavior during the pathogenesis of diabetic retinopathy, i.e., early pericyte drop-out and late endothelial cell proliferation.

Brain stem afferents to the fastigial nucleus in the cat demonstrated by transport of horseradish peroxidase

Although retrograde and anterograde degeneration studies have provided important information concerning brain stem afferents to the fastigal nucleus (FN), these data may be incomplete and should be confirmed by axonal transport methods. Attempts were made to inject horseradish peroxidase (HRP) unilaterally into the FN in a series of adult cats. Animals were perfused with dextran and a fixative solution of paraformaldehyde and glutaraldehyde in 0.1 M phospate buffer. Representative sections were treated by the Graham and Karnovsky ('66) method. Selective HRP injections in one FN resulted in retrograde transport of the marker to Purkinje cells of the ipsilateral vermis and distinctive appendages of the contralateral medial accessory olivary (MAO) nucleus (nucleus beta and the dorso-medial cell column). Retrograde transport of the label was found bilaterally in cells of the medial (MVN) and inferior (IVN) vestibular nuclei, in cell group x and in the nucleus prepositus (PP). Labeled vestibular neurons, most numerous in MVN, were identified in dorsal, caudal and lateral regions, with a slight ipsilateral preponderance. Only a few neurons in caudal, dorsal and lateral regions of the IVN were labeled and none of these included cells of group f. Labeled cells in the caudal third of PP were greatest ipsilaterally. Rostral and caudal injections of FN labeled smaller numbers of cells in MVN, IVN, cell group x and PP. HRP injections of FN and portions of lobules VIII and IX resulted in bilateral retrograde labeling of larger numbers of cells in MVN, IVN and cell group x, and ipsilateral labeling of cells in group y and the interstitial nucleus of the vestibular nerve. Injections of HRP into basal folia of lobules V and VI resulted in retrograde transport of the marker to cells of the medial and dorsal accessory olivary nuclei contralaterally, and to cells of the ipsilateral accessory cuneate nucleus. Transport of label injected into portions of the pyramis was detected in parts of the contralateral MAO and bilaterally in parts of the pontine and reticulotegmental nuclei. This study suggests that the principal afferents of the fastigial nucleus arise from: (1) Purkinje cells of the ipsilateral vermis, (2) restricted portions of the contralateral MAO (nucleus beta and dorsomedial cell column), (3) portions of the MVN and IVN (bilaterally) and (4) caudal parts of the PP. Secondary vestibular inputs to the fastigial nucleus probably are relayed mainly by Purkinje cells in the cerebellar cortex.

Albumin antioxidant capacity is modified by methylglyoxal

OBJECTIVE

Oxidative stress seems to play a major role in diabetic vascular complication development. Plasma albumin, via its thiol groups, is the main extracellular antioxidant molecule. Methylglyoxal (MG) is a very reactive dicarbonyl compound increased in diabetes which strongly modifies proteins by non-enzymatic glycosylation. The aim of this work was to study if MG could modify albumin antioxidant capacity.

METHODS

Bovine serum albumin was incubated with 1 mM MG at 37 degrees C for 7 days (MG-BSA). Albumin physico-chemical changes were evaluated by tryptophan autofluorescence measurement in the presence or in the absence of a quencher (acrylamide). Albumin antioxidant capacity was determined by thiol measurement using Ellman's reagent as well as in a cellular system (HeLa cells stressed by H2O2).

RESULTS

MG-BSA exhibited important modifications as shown by conformational changes, decreased tryptophan autofluorescence (30%) and significant thiol loss (40%). MG-BSA led to important modifications resulting in oxidation and loss of albumin antioxidant capacity. MG-BSA modifications were close to the one observed in albumin isolated from diabetic patients.

CONCLUSION

Our results suggest that deleterious effects induced by carbonyl stress in diabetes could also originate from a loss of albumin antioxidant capacity by dicarbonyl compound attack. The biological consequences of these findings have now to be investigated.

Meta-analysis of genome-wide association studies identifies common variants in CTNNA2 associated with excitement-seeking

The tendency to seek stimulating activities and intense sensations define excitement-seeking, a personality trait akin to some aspects of sensation-seeking. This trait is a central feature of extraversion and is a component of the multifaceted impulsivity construct. Those who score high on measures of excitement-seeking are more likely to smoke, use other drugs, gamble, drive recklessly, have unsafe/unprotected sex and engage in other risky behaviors of clinical and social relevance. To identify common genetic variants associated with the Excitement-Seeking scale of the Revised NEO Personality Inventory, we performed genome-wide association studies in six samples of European ancestry (N=7860), and combined the results in a meta-analysis. We identified a genome-wide significant association between the Excitement-Seeking scale and rs7600563 (P=2 × 10(-8)). This single-nucleotide polymorphism maps within the catenin cadherin-associated protein, alpha 2 (CTNNA2) gene, which encodes for a brain-expressed α-catenin critical for synaptic contact. The effect of rs7600563 was in the same direction in all six samples, but did not replicate in additional samples (N=5105). The results provide insight into the genetics of excitement-seeking and risk-taking, and are relevant to hyperactivity, substance use, antisocial and bipolar disorders.

Myocardial β(2) -adrenoceptor gene delivery promotes coordinated cardiac adaptive remodelling and angiogenesis in heart failure

BACKGROUND AND PURPOSE

We investigated whether β(2) -adrenoceptor overexpression could promote angiogenesis and improve blood perfusion and left ventricular (LV) remodeling of the failing heart.

EXPERIMENTAL APPROACH

We explored the angiogenic effects of β(2) -adrenoceptor overexpression in a rat model of post-myocardial infarction (MI) heart failure (HF). Cardiac adenoviral-mediated β(2) -adrenoceptor overexpression was obtained via direct intramyocardial injection 4-weeks post-MI. Adenovirus(Ad)-GFP and saline injected rats served as controls. Furthermore, we extended our observation to β(2) -adrenoceptor -/- mice undergoing MI.

KEY RESULTS

Transgenes were robustly expressed in the LV at 2 weeks post-gene therapy, whereas their expression was minimal at 4-weeks post-gene delivery. In HF rats, cardiac β(2) -adrenoceptor overexpression resulted in enhanced basal and isoprenaline-stimulated cardiac contractility at 2-weeks post-gene delivery. At 4 weeks post-gene transfer, Ad-β(2) -adrenoceptor HF rats showed improved LV remodeling and cardiac function. Importantly, β(2) -adrenoceptor overexpression was associated with a markedly increased capillary and arteriolar length density and enhanced in vivo myocardial blood flow and coronary reserve. At the molecular level, cardiac β(2) -adrenoceptor gene transfer induced the activation of the VEGF/PKB/eNOS pro-angiogenic pathway. In β(2) -adrenoceptor-/- mice, we found a ~25% reduction in cardiac capillary density compared with β(2) -adrenoceptor+/+ mice. The lack of β(2) -adrenoceptors was associated with a higher mortality rate at 30 days and LV dilatation, and a worse global cardiac contractility compared with controls.

CONCLUSIONS AND IMPLICATION

β(2) -Adrenoceptors play an important role in the regulation of the angiogenic response in HF. The activation of VEGF/PKB/eNOS pathway seems to be strongly involved in this mechanism.

Docosahexaenoic acid is a major n-3 polyunsaturated fatty acid in bovine retinal microvessels

The aim of this study was to purify microvessels from bovine retina and also to cultivate bovine retinal endothelial cells (BRECs) or intramural pericytes, to determine their fatty acid composition. Microvessels were obtained after Dounce homogenization of the retina followed by centrifugation on albumin cushion and finally microvessels in the pellet were trapped on a 100-microns nylon filter. Contamination of microvessel preparations by neuronal tissue, assessed after both microscopic examination and western blotting with a monoclonal antibody raised against rhodopsin, was minor. In the entire bovine retina, docosahexaenoic acid (DHA) represented 23.3% of the total fatty acids and there was about three times less arachidonic acid (AA) (8.2%) than DHA. In contrast, DHA and AA levels were almost equivalent in the retinal microvessels with approximately 10% of total fatty acids. When compared with intact microvessels, the DHA proportion of confluent monolayers of both BRECs or pericytes in primary cultures dropped to approximately 2% of the total fatty acids, whereas AA was unchanged. Culture medium supplementation with unesterified DHA (10 microM) restored the DHA proportion of BRECs close to the microvascular value at the expense of linoleic acid without affecting AA very much. In contrast, DHA supplementation in pericytes increased the DHA proportion of these cells at the expense of AA. In conclusion, DHA of intact microvessels represented 10% of the total fatty acids, which was close to the AA proportion. Mild DHA supplementation of BRECs or pericytes in primary cultures restored their DHA proportion to the original microvessel value. This high percentage of polyunsaturated fatty acids in retinal microvessels should allow us to test the hypothesis that oxidation products derived from these fatty acids may be involved in the pathogenic process leading to diabetic retinopathy.

Angiogenesis and biomarkers of cardiovascular risk in adults with metabolic syndrome

OBJECTIVES

Metabolic syndrome (MetSyn) is associated with an increased risk of atherosclerosis and fatal cardiovascular events. Angiogenesis is thought to contribute to this risk as it might be involved in the progression of atherosclerotic plaques. We investigated the levels of circulating biomarkers of angiogenesis and cardiovascular risk in adults with MetSyn and assessed their association with established metabolic risk factors.

DESIGN

The Genetic Park project is a highly inclusive cross-sectional survey (about 80% of residents) conducted in three isolated populations in Southern Italy. A total of 1000 men and women (age range: 18-98 years) were included in the analysis. Anthropometric and blood pressure measurements were recorded. Metabolic and cardiovascular biomarkers included glucose, triglycerides, total cholesterol, HDL, vascular endothelial growth factor, placental growth factor (PlGF), soluble fms-like tyrosine kinase-1, high-sensitivity C-reactive protein, high-sensitivity troponin T (hs-TnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP).

RESULT

Subjects with MetSyn had higher levels of PlGF and NT-proBNP after adjustment for age, smoking and body mass index. Circulating levels of PlGF, hs-TnT and NT-proBNP were directly related to the number of criteria of MetSyn, and this association interacted with gender. There was a strong correlation between ageing and cardiovascular risk.

CONCLUSIONS

The increase in circulating levels of biomarkers of angiogenesis and cardiac function in subjects with MetSyn mirrors the pathophysiological changes occurring in the cardiovascular system. Over time, these changes might accelerate the formation and progression of atherosclerotic plaques and contribute significantly to cardiovascular morbidity and mortality risk.

Vascular permeability increase as induced by histamine or bradykinin is enhanced by advanced glycation endproducts (AGEs)

Advanced glycation endproducts (AGEs) may enhance vascular permeability in diabetic subjects. To test this hypothesis, AGEs were prepared in the presence of albumin (AGE-Alb). Control albumin (Alb) and AGE-Alb were then labeled with FITC (fluoresceinisothiocyanate) and injected i.v. into anesthetized hamsters at a dose of 7 mg/100 g B.W. Normal hamsters were given FITC-Alb or FITC-AGE-Alb and FITC-dextran. Vascular permeability changes were measured by direct intravital microscopy of the hamster cheek pouch preparations in fluorescent light and recorded as number of sites (=leaks) with extravasation of FITC-labeled albumin in postcapillary venules. No changes were seen during 1 hour after i.v. injection of FITC-Alb or FITC-AGE-Alb. Repeated local application of histamine 5 x 10(6) M or bradykinin 5 x 10(7) M to the cheek pouch for 5 min with 30-min intervals induced reversible increases in vascular permeability in all hamsters. Maximal number of leaks/cm2 before and at 30 and 60 min after FITC-Alb-injection and histamine application was 257 +/- 6 (SEM), 243 +/- 6 and 231 +/- 6 leaks/cm2 in the FITC-Alb-group and 258 + 6 (SEM), 302 +/- 12 and 316 +/- 11 leaks/cm2 in the FITCAGE-Alb-group, respectively, (P < 0.05 at 30 and 60 min). Similar results were seen with bradykinin. Our conclusions showed that i.v.-injected AGEs augmented the histamine- and bradykinin-induced increase in vascular permeability by 34% and 46%.

Advanced glycation end products induce specific glycoprotein alterations in retinal microvascular cells

In order to investigate the mechanisms involved in diabetic retinopathy, we studied the effects of advanced glycosylation end products (AGE) on retinal microvascular cell glycoproteins. Bovine retinal pericytes (BRP) and endothelial cells (BREC) were incubated in the presence of AGE-modified albumin and cell glycoproteins analyzed by lectin affinoblotting and metabolic radiolabeling with sugar precursors. Selective modifications in the glycoprotein sugar chains were observed mainly in BREC and for a 210 kDa membrane glycoprotein. Indeed, a 40% decrease of alpha(2,3) sialic acid, beta(1,3) galactose or alpha(1,6) fucose content was observed without significant protein amount changes. These glycoprotein alterations were related to the concentration of AGE. Neither BRP nor BREC glycoproteins were modified when cells were incubated with high glucose or fructose concentrations. These results suggest a new diabetic pathogenic mechanism in which a protein post-translational modification, in this case glycation, could modify another post-translational process such as the enzymatic glycosylation.

Whole-Exome Sequencing in the Isolated Populations of Cilento from South Italy

The present study describes the genetic architecture of the isolated populations of Cilento, through the analysis of exome sequence data of 245 representative individuals of these populations. By annotating the exome variants and cataloguing them according to their frequency and functional effects, we identified 347,684 variants, 67.4% of which are rare and low frequency variants, and 1% of them (corresponding to 319 variants per person) are classified as high functional impact variants; also, 39,946 (11.5% of the total) are novel variants, for which we determined a significant enrichment for deleterious effects. By comparing the allele frequencies in Cilento with those from the Tuscan population from the 1000 Genomes Project Phase 3, we highlighted an increase in allele frequency in Cilento especially for variants which map to genes involved in extracellular matrix formation and organization. Furthermore, among the variants showing increased frequency we identified several known rare disease-causing variants. By different population genetics analyses, we corroborated the status of the Cilento populations as genetic isolates. Finally, we showed that exome data of Cilento represents a useful local reference panel capable of improving the accuracy of genetic imputation, thus adding power to genetic studies of human traits in these populations.

Glycosphingolipid changes induced by advanced glycation end-products

The effects of advanced glycation end-products (AGEs) on retinal microvascular cell glycosphingolipids were investigated as a potential pathogenic mechanism of diabetic retinopathy. The results obtained showed that, in microvascular retinal endothelial cells and pericytes, AGEs increased the amount of all glycosphingolipids studied (from 25 to 115% depending on the glycosphingolipid species), except for a specific ganglioside, GD3, which decreased by 35% only in pericytes. Glycosphingolipid profiles and GM3 fatty acid analysis did not show any qualitative differences after incubation with AGEs, suggesting that AGEs only induced quantitative changes in cell glycosphingolipids. These results show a new metabolic effect of AGEs, which could be involved in the microvascular alterations observed in diabetic retinopathy.

Involvement of cell-cell interactions in the pathogenesis of diabetic retinopathy

Retinopathy is a severely disabling complication of diabetes mellitus whose underlying mechanisms are still obscure. The key question is why retinal microvessels are so reactive to the diabetic environment, whereas other microvessels show no evidence of alteration. The answer could lie in the particular structure and location of retinal microvessels since they are composed of, and surrounded by, various types of cells, thereby favouring cell-cell interactions which occur between cells of the capillary wall itself but also with circulating blood cells and retinal neural cells. In the retinal capillary wall, pericytes are in close relation with underlying endothelial cells, and both cell types have close contacts with the capillary basement membrane. Adhesion molecules and cell surface glycoconjugates appear to be the main mediators of interactions between circulating blood cells and capillary endothelial cells, whereas growth factors seem to play a major role in interactions between glial and capillary wall cells in the retina. Biochemical dysfunctions observed in diabetes, such as glycation of proteins and enhanced oxidative stress, could modify these cell-cell and cell-matrix interactions, thereby disturbing the complex cellular organization in which retinal microvessels are embedded. The aim of this review was to provide an overall, nonexhaustive description of some types of cellular interactions that may underlie the pathogenic mechanisms involved in flow and growth changes leading to diabetic retinopathy.

[Distribution of anti-HAV in a population sample from Puglia]

To investigate the prevalence and distribution of antibody to hepatitis A virus (anti-HAV), we tested by solid phase radioimmunoassay method 461 sera of selected people of Bari, according to age. In addiction, sera from cord blood of 11 newborns and their mothers at delivery were also investigated for anti-HAV. Taken together 64.4 per cent of subjects tested were found to be anti-HAV positive. The rate of antibody detection was strongly correlated with age. The prevalence were 4.5 per cent from 6 months to 3 years but gradually increased throughout childhood (from 35.6 to 80 per cent). Anti-HAV was detected in all cord blood samples from newborns whose mothers carried anti-HAV. These data suggest that circulation of hepatitis A virus in our area is very high, so that serological evidence of infection become evident in the majority of individuals during infancy.