A Descriptive Chemical Composition of Concentrated Bud Macerates through an Optimized SPE-HPLC-UV-MS2 Method-Application to Alnus glutinosa, Ribes nigrum, Rosa canina, Rosmarinus officinalis and Tilia tomentosa

Concentrated bud macerates (CBMs) are obtained from meristematic tissues such as buds and young shoots by maceration in a solvent composed of glycerin, water and ethanol (1/1/1/, v/v). Their traditional utilization in gemmotherapy has gained interest in the past years, and the knowledge of their chemical characterization can provide commercial arguments, particularly to secure their quality control. Therefore, an optimized method for phytochemical analysis including glycerol removal by a preliminary solid phase extraction (SPE) followed by compound identification using high performance liquid chromatography coupled with ultra-violet and tandem mass detectors (HPLC-UV-MS²) was developed. This method was applied on 5 CBMs obtained from Alnus glutinosa, Ribesnigrum, Rosmarinus officinalis, Rosa canina and Tilia tomentosa in order to determinate their chemical composition. Their antioxidant effects were also investigated by radical scavenging activity assays (DPPH and ORAC). Glycerol removal improved the resolution of HPLC chemical profiles and allowed us to perform TLC antioxidant screening. Our approach permitted the identification of 57 compounds distributed in eight major classes, three of them being common to all macerates including nucleosides, phenolic acids and glycosylated flavonoids. Quantification of the later class as a rutin equivalent (RE) showed a great disparity between Rosa canina macerate (809 mg RE/L), and the other ones (from 175 to 470 mg RE/L). DPPH and ORAC assays confirmed the great activity of Rosa canina (4857 and 6479 μmol TE/g of dry matter, respectively). Finally, phytochemical and antioxidant analysis of CBMs strengthened their phytomedicinal interest in the gemmotherapy field.

Anti-inflammatory Effects of a Sesquiterpene Lactone Extract from Chicory (Cichorium intybus L.) Roots

A chicory root extract rich in sesquiterpene lactones significantly reduced inflammation in two animal models. In a rat paw edema model, chicory extract at 50 and 100 mg/kg significantly reduced inflammation by 58 and 76%, respectively, 24 h after carrageenan injection. In a mouse collagen induced arthritis model, chicory extract (200 mg/kg) reduced paw edema by 71% while the extract was being administered, and 31% 48 h after extract administration was discontinued. Two possible modes of action were investigated, pro-inflammatory gene expression and nitric oxide production by LPS-elicited macrophages. Chicory root extract down-regulated COX-2, TNF-α, IL1β, and iNOS expression and reduced nitric oxide production in a dose dependant manner. Several compounds were isolated from the chicory extract and tested in vitro to confirm activity. Dihydrolactucopicrin and 8-deoxylactucin showed particularly high nitric oxide inhibitory activity (IC50 = 13 μM for both). Dihydrolactucopicrin also was shown to down-regulate pro-inflammatory gene expression. These data demonstrate that chicory extracts rich in sesquiterpene lactones have potent anti-inflammatory activity with potential therapeutic use.

Effect of zein additive on perfume evaporation

OBJECTIVE

Zein is known to have filmogen properties. We wanted to show if a zein film containing eugenol (eugenol as model) would retain the fragrances, slow their evaporation and therefore produce a long-lasting perception of perfume.

METHODS

We added corn zein to eugenol in a hydro-alcoholic solution to form a film in vitro and at the surface of the human skin. We have studied the trapping and release of eugenol from zein film by GC/MS. Also we labelled eugenol with deuterium to image specifically its distribution in the zein film using Secondary Ion Mass Spectrometry technique (NanoSIMS 50). Finally, we applied the zein/D-eugenol formulation onto skin to image the eugenol location on and in skin by SIMS (Secondary Ion Mass Spectrometry).

RESULTS

We showed that eugenol evaporation from zein film can be divided in three periods. The first period (≤2 h) corresponds to the simultaneous solvent and eugenol evaporation occurring during film formation. The second period corresponds to the continuous and slow eugenol evaporation during a few hours (about 10 h) but not to its completion. The third period (at least up to 48 h) results from the trapping of eugenol in zein film. After 24 or 48 h, trapped eugenol can be released and evaporated under mechanical deformations of the film. Moreover we showed that zein addition does not favour the eugenol penetration into viable epidermis which may cause allergenic cutaneous reaction.

CONCLUSION

The zein additive is safe to use, does not impact the olfactory perception, allows a better perception of the fragrance (long-lasting effect) in a more protective way and can be used in perfume.

Cellular and molecular characterization of IDH1-mutated diffuse low grade gliomas reveals tumor heterogeneity and absence of EGFR/PDGFRα activation

Diffuse low grade gliomas (DLGG, grade II gliomas) are slowly-growing brain tumors that often progress into high grade gliomas. Most tumors have a missense mutation for IDH1 combined with 1p19q codeletion in oligodendrogliomas or ATRX/TP53 mutations in astrocytomas. The phenotype of tumoral cells, their environment and the pathways activated in these tumors are still ill-defined and are mainly based on genomics and transcriptomics analysis. Here we used freshly-resected tumors to accurately characterize the tumoral cell population and their environment. In oligodendrogliomas, cells express the transcription factors MYT1, Nkx2.2, Olig1, Olig2, Sox8, four receptors (EGFR, PDGFRα, LIFR, PTPRZ1) but not the co-receptor NG2 known to be expressed by oligodendrocyte progenitor cells. A variable fraction of cells also express the more mature oligodendrocytic markers NOGO-A and MAG. DLGG cells are also stained for the young-neuron marker doublecortin (Dcx) which is also observed in oligodendrocytic cells in nontumoral human brain. In astrocytomas, MYT1, PDGFRα, PTPRZ1 were less expressed whereas Sox9 was prominent over Sox8. The phenotype of DLGG cells is overall maintained in culture. Phospho-array screening showed the absence of EGFR and PDGFRα phosphorylation in DLGG but revealed the strong activation of p44/42 MAPK/ERK which was present in a fraction of tumoral cells but also in nontumoral cells. These results provide evidence for the existence of close relationships between the cellular phenotype and the mutations found in DLGG. The slow proliferation of these tumors may be associated with the absence of activation of PDGFRα/EGFR receptors.

Stepwise diagnosis in covert hepatic encephalopathy: critical flicker frequency and MELD-score as a first-step approach

BACKGROUND

The diagnosis of covert hepatic encephalopathy (CHE) by means of portosystemic encephalopathy syndrome (PSE) test is costly and therefore infrequently performed.

AIM

To determine the ability of critical flicker frequency (CFF) alone or in combination with laboratory findings, as an initial test to pre-select which patients should undergo further testing for the diagnosis of covert hepatic encephalopathy.

METHODS

This single-centre study included all patients with cirrhosis who underwent PSE and CFF in 2011. CHE was defined by abnormal PSE test. Logistic regression analysis was performed to identify predictors of CHE. ROC curves were used to identify cut-offs of these independent predictors.

RESULTS

One hundred and seventeen patients were included. Seventy (60%) had CHE with a higher MELD [16 (IQR 13-21); P = 0.001] and lower CFF [38 Hz (IQR 36-41) P = 0.0011]. On multivariate analyses, CFF [OR 0.83 (95% CI 0.74-0.94)] and MELD [OR 1.13 (95% CI 1.04-1.22)] were identified as independent predictors of CHE. Sensitivity and specificity of a CFF cut-off of 43 Hz was 93.5% and 42.9%, and for a MELD cut-off of 24, it was 97.5% and 32.8% respectively. Most patients with a MELD-Score <24 and a CFF >43 Hz did not have CHE (78%) and with a MELD-Score >24 and CFF <43 Hz most patients had CHE (85%). Therefore, 27% of patients could avoid further testing with a diagnostic accuracy of 81%.

CONCLUSION

The combination of MELD-score and critical flicker frequency may be used as a first diagnostic step to filter patients, in whom further covert hepatic encephalopathy testing could be avoided.

Does larch arabinogalactan enhance immune function? A review of mechanistic and clinical trials

The common cold is a viral infection with important economic burdens in Western countries. The research and development of nutritional solutions to reduce the incidence and severity of colds today is a major focus of interest, and larch arabinogalactan seems to be a promising supportive agent. Arabinogalactan has been consumed by humans for thousands of years and is found in a variety of common vegetables as well as in medicinal herbs. The major commercial sources of this long, densely branched, high-molecular-weight polysaccharide are North American larch trees. The aim of this article is to review the immunomodulatory effects of larch arabinogalactan derived from Larix laricina and Larix occidentalis (North American Larix species) and more specifically its role in the resistance to common cold infections. In cell and animal models, larch arabinogalactan is capable of enhancing natural killer cells and macrophages as well as the secretion of pro-inflammatory cytokines. In humans a clinical study demonstrated that larch arabinogalactan increased the body’s potential to defend against common cold infection. Larch arabinogalactan decreased the incidence of cold episodes by 23 %. Improvements of serum antigen-specific IgG and IgE response to Streptococcus pneumoniae and tetanus vaccination suggesting a B cell dependent mechanism have been reported in vaccination studies with larch arabinogalactan, while the absence of response following influenza vaccination suggests the involvement of a T cell dependent mechanism. These observations suggest a role for larch arabinogalactan in the improvement of cold infections, although the mode of action remains to be further explored. Different hypotheses can be envisaged as larch arabinogalactan can possibly act indirectly through microbiota-dependent mechanisms and/or have a direct effect on the immune system via the gut-associated lymphoid tissue (GALT).

Evaluation of the anti-inflammatory and antioxidative potential of four fern species from China intended for use as food supplements

Inflammation plays a major role in many diseases, for instance in arteriosclerosis, rheumatoid arthritis, autoimmune disorders and cancer. Since many plants contain compounds with anti-inflammatory activity, their consumption may be able to prevent the development of inflammatory-based diseases. Edible ferns are some of the most important wild vegetables in China and have traditionally been used both for dietary and therapeutic purposes. In this study we investigated the anti-inflammatory and antioxidant potential of fern extracts from Matteuccia struthiopteris, Osmundajaponica, Matteuccia orientalis and Pteridium aquilinum intended for use as nutraceuticals. Two modes of action were investigated: the inhibition of the pro-inflammatory gene expression of interleukin-1 beta (IL1-β) and interleukin-6 (IL6), and the gene expression of iNOS by LPS-elicited macrophages. The results showed a decrease of IL1-β gene expression for the five fern extracts. This effect was more pronounced for the extracts prepared from the roots of O. japonica (IC50 of 17.8 µg/mL) and the young fronds of M orientalis (50.0 µg/mL). Regarding the indirect measurement of NO, via iNOS gene expression, an interesting decrease of 50% was obtained with the extract of M. orientalis fronds at a low concentration (20 µg/mL) compared with P. aquilinum fronds (160 µg/mL) and leaves of O. japonica. The latter showed a higher decrease but at a high concentration of extract (160 µg/mL). The five fern extracts were also evaluated for their ability to scavenge 2,2-diphenyl-l-picrylhydrazyl (DPPH) radicals and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). All fern extracts exhibited antioxidant effects but the roots of O. japonica and the fronds of M orientalis were most efficient. The HPLC-MS analysis of the constituents of the fern extracts confirmed the presence of chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, kaempferol and apigenin, molecules known to exhibit antiinflammatory and/or antioxidant properties.

Evaluation of the Anti-inflammatory and Antioxidative Potential of Four Fern Species from China Intended for Use as Food Supplements

Inflammation plays a major role in many diseases, for instance in arteriosclerosis, rheumatoid arthritis, autoimmune disorders and cancer. Since many plants contain compounds with anti-inflammatory activity, their consumption may be able to prevent the development of inflammatory-based diseases. Edible ferns are some of the most important wild vegetables in China and have traditionally been used both for dietary and therapeutic purposes. In this study we investigated the anti-inflammatory and antioxidant potential of fern extracts from Matteucca struthiopteris, Osmunda japonica, Matteuccia oriental and Pteridium aquilinum intended for use as nutraceuticals. Two modes of action were investigated: the inhibition of the pro-inflammatory gene expression of interleukin-1 beta (IL1-β) and interleukin-6 (IL6), and the gene expression of iNOS by LPS-elicited macrophages. The results showed a decrease of IL1-β gene expression for the five fern extracts. This effect was more pronounced for the extracts prepared from the roots of O. japonica (IC50 of 17.8 μg/mL) and the young fronds of M. orientalis (50.0 μg/mL). Regarding the indirect measurement of NO, via iNOS gene expression, an interesting decrease of 50% was obtained with the extract of M. orientalis fronds at a low concentration (20 μg/mL) compared with P. aquilinum fronds (160 μg/mL) and leaves of O. japonica. The latter showed a higher decrease but at a high concentration of extract (160 μg/mL). The five fern extracts were also evaluated for their ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). All fern extracts exhibited antioxidant effects but the roots of O. japonica and the fronds of M. orientalis were most efficient. The HPLC-MS analysis of the constituents of the fern extracts confirmed the presence of chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, kaempferol and apigenin, molecules known to exhibit antiinflammatory and/or antioxidant properties.

Acute effect of Ceylon cinnamon extract on postprandial glycemia: alpha-amylase inhibition, starch tolerance test in rats, and randomized crossover clinical trial in healthy volunteers

BACKGROUND

Postprandial hyperglycemia is a known risk factor for the development of several health disorders including type 2 diabetes, obesity, oxidative stress, and cardiovascular diseases. One encouraging approach for a better control of postprandial glycemia is to reduce carbohydrate digestion. Cinnamon extracts have been known for managing blood glucose. However, their effects on inhibiting digestion of carbohydrate have been poorly analyzed to date. The aim of this study was to investigate the acute effect of a specific Ceylon cinnamon hydro-alcoholic extract (CCE) on carbohydrate digestion and post-meal blood glucose reduction.

METHODS

In vitro enzymatic assays and in vivo starch tolerance tests in rats were designed as preclinical assays. Then, a randomized, double-blind, placebo-controlled, cross-over clinical trial was conducted in 18 healthy female and male volunteers. Following the intake of 1 g of CCE, the subjects ate a standardized meal. Blood samples were collected during the 2 hours following the meal to measure glucose and insulin concentrations. Areas under the curves were calculated and statistical differences between the CCE and placebo groups were analyzed using the Mann Whitney-Wilcoxon test.

RESULTS

CCE has demonstrated in the in vitro study that it inhibited pancreatic alpha-amylase activity with an IC50 of 25 μg/mL. In the in vivo study, CCE was shown to acutely reduce the glycemic response to starch in a dose-dependent manner in rats. This effect was significant from the dose of 12.5 mg/kg of body weight. In both, the in vitro and in vivo studies, the hydro-alcoholic extract has shown to be more efficacious than the aqueous extract. In the human clinical trial, 1 g of CCE lowered the area under the curve of glycemia between 0 and 120 min by 14.8% (P = 0.15) and between 0 and 60 min by 21.2% (P < 0.05) compared to the placebo. This effect occurred without stimulating insulin secretion. No adverse effects were reported.

CONCLUSION

These results suggest that Ceylon cinnamon hydro-alcoholic extract (CCE) may provide a natural and safe solution for the reduction of postprandial hyperglycemia and therefore help to reduce the risks of developing metabolic disorders.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02074423 (26/02/2014).

Use of transient elastography (FibroScan®) for the noninvasive assessment of portal hypertension in HIV/HCV-coinfected patients

The hepatic venous pressure gradient (HVPG) is the gold standard for assessing portal pressure and correlates with the occurrence of portal hypertension (PH)-related complications. Transient elastography (TE) is a new, highly accurate noninvasive technique, which enables us to evaluate hepatic fibrosis to detect advanced fibrosis and cirrhosis. We performed a hepatic haemodynamic study and TE in 38 HIV/HCV-coinfected patients. The association between HVPG and liver stiffness was assessed by linear regression. The diagnostic value of TE was assessed by receiver operating characteristic (ROC) curves. We considered clinically significant PH as an HVPG ≥ 10 mmHg and severe PH as an HVPG ≥ 12 mmHg. A total of 38 HIV/HCV-coinfected patients were included. Twenty-eight patients (73.7%) had clinically significant PH (HVPG ≥ 10 mmHg), and 23 (60.5%) of these had severe PH (HVPG ≥ 12 mmHg). We found a statistically significant association between liver stiffness (kPa) and HVPG (r(2) = 0.46, P < 0.001, straight line equation HVPG=7.4 + 0.204*TE). The areas under the ROC curves were 0.80 [95% confidence interval (CI), 0.64-0.97] and 0.80 (95% CI, 0.66-0.94) for the prediction of HVPG ≥ 10 and ≥ 12 mmHg, respectively. Our data suggest that TE can predict the presence of clinically significant and severe PH in HIV/HCV-coinfected patients.

Nutraceuticals: do they represent a new era in the management of osteoarthritis? - a narrative review from the lessons taken with five products

OBJECTIVES

The aim of this first global systematic review on selected nutraceuticals was to synthesize and evaluate scientific relevant data available in the literature. Evidences that can support health, physiological or functional benefit on osteoarthritis (OA) were gathered and the level of evidence relative to each of these ingredients was highlighted.

METHODOLOGY

Relevant scientific data (positive or not) regarding OA were searched for five groups of compounds (avocado/soybean unsaponifiables (ASU), n-3 polyunsaturated fatty acids, collagen hydrosylates (CHs), vitamin D, polyphenols) within preclinical (in vitro and in vivo), epidemiological, and clinical studies. The following criteria were evaluated to assess the methodology quality of each study: (1) study question; (2) study population; (3) primary endpoint; (4) study design (randomization, control, blinding, duration of follow up); (5) data analysis and interpretation. A scientific consensus was determined for all studied nutraceuticals to evaluate their efficacy in OA.

RESULTS

The studied compounds demonstrated different potencies in preclinical studies. Most of them have demonstrated anti-catabolic and anti-inflammatory effects by various inhibitory activities on different mediators. Vitamin D showed a pro-catabolic effect in vitro and the polyphenol, Genistein, had only anti-inflammatory potency. The evaluation of the clinical data showed that ASU was the only one of the studied ingredients to present a good evidence of efficacy, but the efficient formulation was considered as a drug in some countries. Pycnogenol showed moderate evidence of efficacy, and vitamin D and collagen hydrolysate demonstrated a suggestive evidence of efficacy, whereas curcumin, epigallocatechin-3-gallate (EGCG) and resveratrol had only preclinical evidence of efficacy due to the lack of clinical data. The literature gathered for n-3 PUFA, nobiletin and genistein was insufficient to conclude for their efficacy in OA.

CONCLUSION

Additional data are needed for most of the studied nutraceuticals. Studies of good quality are needed to draw solid conclusions regarding their efficacy but nutraceuticals could represent good alternates for OA management. Their use should be driven by any recommendations.

Importance of extract standardization and in vitro/ex vivo assay selection for the evaluation of antioxidant activity of botanicals: a case study on three Rosmarinus officinalis L. extracts

The overproduction of free radicals and oxygen reactive species is suspected to be implicated in a wide range of metabolic reactions that can have pernicious consequences in the development of a variety of human diseases. Botanical extracts are sources of antioxidants that counteract both free radicals and oxygen reactive species. The processing conditions used in the botanical extraction may influence the antioxidant composition; therefore, different extracts from the same plant may have different antioxidant properties. To illustrate this fact, we conducted a study using three commercial rosemary (Rosmarinus officinalis L.) leaf extracts. The three extracts were standardized to contain, respectively, 20% carnosic acid, 40% ursolic acid, or 20% rosmarinic acid. They were evaluated for their total (hydrophilic + lipophilic) antioxidant effects on oxygen radical absorbance capacity (ORAC), their ferric reducing/antioxidant power (FRAP), and their capacity to inhibit Cu(2+)-induced low-density lipoprotein (LDL) oxidation ex vivo. The ursolic acid extract showed the lowest antioxidant capacity on all models. The rosmarinic acid extract had an antioxidant capacity 1.5 times higher on ORAC and four times higher on FRAP than the carnosic acid extract. However, the carnosic acid extract was better than the rosmarinic acid extract in inhibiting the oxidation of LDL ex vivo. These results encourage conducting further studies to evaluate the carnosic acid and rosmarinic acid extracts in vivo. Our study offers an example of the importance of the extraction procedures, on which depends the nature of the antioxidant composition, and highlights interest to proceed with in vitro/ex vivo assay selection for the evaluation of the antioxidant properties of botanical extracts.

Gastrointestinal tolerance to an inulin-rich soluble roasted chicory extract after consumption in healthy subjects

OBJECTIVES

We aimed to assess in healthy subjects 1) the effect of two doses of a new naturally inulin-rich soluble chicory extract (IRSCE) on overall gastrointestinal discomfort after short-term ingestion and 2) the effect on gastrointestinal symptoms of long-term consumption of IRSCE administered at a dose compatible with its future commercial use.

METHODS

First, the effect of IRSCE was assessed on overall gastrointestinal discomfort in a double-blind, crossover study where 18 subjects received in a randomized order a morning coffee drink including 10 g of sucrose alone (control period) or with IRSCE at two doses (8.9 and 14.0 g containing 5.0 and 7.8 g of inulin, respectively) during three consecutive 6-d periods. Second, 35 subjects were followed during a randomized, double-blind protocol where they were asked to take twice a day an instant coffee drink containing IRSCE (8.1 g/d containing inulin 5.0 g/d) or sucrose 8.1 g/d during 4 wk. The effects of the treatment on flatulence, bloating, abdominal pain, stool consistency, and number were recorded.

RESULTS

In the first study a significant slight increase (P = 0.05) in overall abdominal discomfort was observed with the morning coffee drink containing 7.8 g of inulin after 1 wk of consumption. In the second study, no significant differences between the IRSCE and placebo groups were evidenced with respect to gastrointestinal symptoms during the consumption period.

CONCLUSION

Short- and long-term consumptions of IRSCE, given at a daily dose containing 5 g of inulin, are well tolerated by healthy subjects.

Fenugreek Extract Rich in 4-Hydroxyisoleucine and Trigonelline Activates PPARα and Inhibits LDL Oxidation: Key Mechanisms in Controlling the Metabolic Syndrome

Fenugreek ( Trigonella foenum-graecum L.) has properties which are hypolipidemic, hypocholesterolemic, hypoglycemic, insulinotropic, and antioxidant. These properties are related to the control of the Metabolic Syndrome, a disorder of carbohydrate and lipid metabolism which increases the risk of diabetes and cardiovascular disease. The purpose of this study was to evaluate the effect of fenugreek extract (Hydroxylean®, Naturex) containing 25% of 4-hydroxyisoleucine (4-OH-Ile, isomer 2 S,3 R,4 S) and 15.7% of trigonelline on peroxisome proliferator-activated receptor alpha (PPARα) transcriptional activity and Cu2+-induced low-density lipoprotein (LDL) oxidation in vitro. The activation of PPARα is linked to controlling lipidemia, cholesterolemia and glycemia, all associated with diabetes and cardiovascular disease. Also, the inhibition of LDL oxidation reduces the risk of stroke. 1,000 μg/mL of fenugreek extract showed a 31.2% activation of PPARα as compared with the positive control, 100 μM of fenofibrate. Fenugreek extract also inhibited LDL oxidation induced by Cu2+ at concentrations higher than 5 μg/mL (P<0.01). To our knowledge, this is the first report on PPARα transcriptional activity and Cu2+-induced LDL oxidation in vitro for fenugreek extract rich in 4-OH-Ile and trigonelline. The findings support the current evidence on fenugreek's capacity to control the Metabolic Syndrome.

Method for macromolecular colocalization using atomic recombination in dynamic SIMS

Localizing two or more components of assemblies in biological systems requires both continued development of fluorescence techniques and invention of entirely new techniques. Candidates for the latter include dynamic secondary ion mass spectrometry (D-SIMS). The latest generation of D-SIMS, the Cameca NanoSIMS 50, permits the localization of specific, isotopically labeled molecules and macromolecules in sections of biological material with a resolution in the tens of nanometers and with a sensitivity approaching in principle that of a single protein. Here we use two different systems, crystals of glycine and mixtures of proteins, to show that the formation of recombinant CN secondary ions under Cs bombardment can be exploited to create a new colocalization technique. We show experimentally that the formation of the recombinant (13)C(15)N secondary ion between (13)C- and (15)N-labeled macromolecules is indeed an indicator of the distance between the interacting macromolecules and on their shape. We build up a convolution model of the mixing-recombination process in D-SIMS that allows quantitative interpretations of the distance-dependent formation of the recombinant CN. Our results show that macromolecules can be colocalized if they are within 2 nm of one another. We discuss the potential advantages of this new technique for biological applications.

Promyelocytic leukemia-nuclear body formation is an early event leading to retinoic acid-induced differentiation of neuroblastoma cells

Neuroblastoma is one of the most common cancers in children. Neuroblastoma differentiation is linked to the presence of the promyelocytic leukemia (PML) protein. Retinoic acid, a powerful differentiation-inducer in vitro, is a potent agent for the treatment of neuroblastoma. Using two different human neuroblastoma cell lines, SH-SY5Y and LA-N-5, we show here that PML protein leads to the formation of nuclear bodies (PML-NB) after only 1 h of retinoic acid treatment and that this formation is mediated by the extracellular signal-regulated kinase (ERK) pathway. Inhibition of protein kinase C also leads to formation of PML-NB via the ERK pathway. Both sumoylation and phosphorylation of PML in an ERK-dependent pathway are also required for formation of PML-NB. Finally, we show that PML-NB formation in neuroblastoma cells is associated with neurite outgrowth. These results support the proposal that the formation of PML-NB is correlated with the differentiation of neuroblastoma cells.

Bisphenol-A disruption of the endocrine pancreas and blood glucose homeostasis

The link between endocrine disruptors and altered blood glucose homeostasis has been recently suggested. Epidemiological studies have correlated levels of phthalates, dioxins and persistent organic pollutants with alterations of blood glucose homeostasis in humans. Environmentally relevant doses of the ubiquitous endocrine disruptor bisphenol-A (BPA) have profound effects on mice endocrine pancreas--an essential tissue involved in glucose metabolism. BPA exerts rapid non-genomic effects on insulin releasing beta-cells and glucagon releasing alpha-cells within freshly isolated islets of Langerhans. In vivo, a single BPA injection of 10 microg/kg rapidly increases plasma insulin and concomitantly decreases glycaemia. When mice were treated with BPA 100 microg/kg/day for 4 days, the environmental oestrogen produced an increase in beta-cell insulin content along with a post-prandial hyperinsulinaemia and insulin resistance. The results reviewed here demonstrate that doses well below the current lowest observed adverse effect level considered by the US-EPA, disrupt pancreatic beta-cell function producing insulin resistance in male mice. Therefore, this altered blood glucose homeostasis by BPA exposure may enhance the risk of developing type II diabetes.

Prognostic value of hepatic venous pressure gradient for in-hospital mortality of patients with severe acute alcoholic hepatitis

BACKGROUND

Hepatic venous pressure gradient (HVPG) has prognostic value in complications and survival of patients with liver cirrhosis. However, the relationship between HVPG and the outcome of acute alcoholic hepatitis (AAH), as well as the specific features of portal hypertension syndrome in this setting, have not been defined.

AIMS

To evaluate the prognostic value of HVPG and to analyse the degree of portal hypertension and hyperdynamic circulation in patients with severe AAH.

METHODS

Early measurements of HVPG were performed in 60 patients with severe AAH, and compared with the haemodynamic findings of 37 and 29 liver transplantation candidates with alcoholic or viral end-stage cirrhosis respectively.

RESULTS

Twenty-three patients (38%) died during hospitalization. Portal hypertension and hyperdynamic circulation were more severe in AAH patients. HVPG was greater in non-survivors [26.9 (7.4) vs. 19.4 (5.2) mmHg, P < 0.001]. Only 4/31 (13%) patients with HVPG <or= 22 mmHg died from the episode of AAH, vs. 19/29 (66%) patients with HVPG > 22 (P < 0.001). Encephalopathy (OR 9.4; CI 1.4-64.8), Model for End-Stage Liver Disease (MELD) score > 25 (OR 7.4; CI 1.4-39.9) and HVPG > 22 mmHg (OR 6.7; CI 1.1-39.9) were independently associated to in-hospital mortality.

CONCLUSIONS

Early measurement of HVPG provides important prognostic information on the short-term outcome of patients with severe AAH. In addition, MELD score also seems to be a strong prognostic factor in these patients.

Increased intrahepatic and circulating levels of endoglin, a TGF-beta1 co-receptor, in patients with chronic hepatitis C virus infection: relationship to histological and serum markers of hepatic fibrosis

Endoglin, a transforming growth factor (TGF)-beta1 co-receptor, has been associated with renal and cutaneous fibrosis, as overexpression of this protein has been observed in biopsies from patients with glomerulosclerosis and scleroderma, respectively. Our aim was to evaluate whether endoglin may be associated with hepatic fibrosis featuring chronic hepatitis C virus (HCV) infection. Fifty-two anti-HCV+ patients, five anti-HCV- patients and 27 healthy subjects were studied. Western blot and immunohistochemistry were used to quantify the expression levels of endoglin and TGF-beta1 in liver biopsy samples, and serum concentrations of endoglin and hyaluronic acid were determined by enzyme-linked immunosorbent assays (ELISAs). In patients with advanced fibrosis, intrahepatic expression levels of endoglin and TGF-beta1 were significantly higher than those in patients with early fibrosis (mean: 3- and 5.8-fold, respectively) and normal liver (mean: 3.9- and 12-fold, respectively). Interestingly, activated hepatic stellate cells as well as portal and septal myofibroblasts expressed endoglin. Serum levels of endoglin were also significantly higher in patients with advanced fibrosis than in those with early fibrosis (55.5 +/- 1.6 vs 47.5 +/- 0.9 ng/mL, P < 0.001), showing a positive correlation with serum hyaluronic acid concentrations (r = 0.57, P = 0.01). In conclusion, increased intrahepatic endoglin and TGF-beta1 expression is significantly associated with progressive hepatic fibrosis in chronic HCV infection. Circulating endoglin levels are elevated in HCV patients showing a significant correlation with histological and serum markers of hepatic fibrosis. These data suggest an active role for endoglin in the fibrotic process featuring chronic HCV infection.

Relative Sensitivity Factors of Inorganic Cations in Frozen-hydrated Standards in Secondary Ion MS Analysis

We describe the measurement, at 100 K, of the SIMS relative sensitivity factors (RSFs) of the main physiological cations Na+, K+, Mg2+, and Ca2+ in frozen-hydrated (F-H) ionic solutions. Freezing was performed by either plunge freezing or high-pressure freezing. We also report the measurement of the RSFs in flax fibers, which are a model for ions in the plant cell wall, and in F-H ionic samples, which are a model for ions in the vacuole. RSFs were determined under bombardment with neutral oxygen (FAB) for both the fibers and the F-H samples. We show that referencing to ice-characteristic secondary ions is of little value in determining RSFs and that referencing to K is preferable. The RSFs of Na relative to K and of Ca relative to Mg in F-H samples are similar to their respective values in fiber samples, whereas the RSFs of both Ca and Mg relative to K are lower in fibers than in F-H samples. Our data show that the physical factors important for the determination of the RSFs are not the same in F-H samples and in homogeneous matrixes. Our data show that it is possible to perform a SIMS relative quantification of the cations in frozen-hydrated samples with an accuracy on the order of 15%. Referencing to K permits the quantification of the ionic ratios, even when the absolute concentration of the referencing ion is unknown. This is essential for physiological studies of F-H biological samples.

Memory processes in the response of plants to environmental signals

Plants are sensitive to stimuli from the environment (e.g., wind, rain, contact, pricking, wounding). They usually respond to such stimuli by metabolic or morphogenetic changes. Sometimes the information corresponding to a stimulus may be "stored" in the plant where it remains inactive until a second stimulus "recalls" this information and finally allows it to take effect. Two experimental systems have proved especially useful in unravelling the main features of these memory-like processes.In the system based on Bidens seedlings, an asymmetrical treatment (e.g., pricking, or gently rubbing one of the seedling cotyledons) causes the cotyledonary buds to grow asymmetrically after release of apical dominance by decapitation of the seedlings. This information may be stored within the seedlings, without taking effect, for at least two weeks; then the information may be recalled by subjecting the seedlings to a second, appropriate, treatment that permits transduction of the signal into the final response (differential growth of the buds). Whilst storage is an irreversible, all-or-nothing process, recall is sensitive to a number of factors, including the intensity of these factors, and can readily be enabled or disabled. In consequence, it is possible to recall the stored message several times successively.In the system based on flax seedlings, stimulation such as manipulation stimulus, drought, wind, cold shock and radiation from a GSM telephone or from a 105 GHz Gunn oscillator, has no apparent effect. If, however, the seedlings are subjected at the same time to transient calcium depletion, numerous epidermal meristems form in their hypocotyls. When the calcium depletion treatment is applied a few days after the mechanical treatment, the time taken for the meristems to appear is increased by a number of days exactly equal to that between the application of the mechanical treatment and the beginning of the calcium depletion treatment. This means that a meristem-production information corresponding to the stimulation treatment has been stored in the plants, without any apparent effect, until the calcium depletion treatment recalls this information to allow it to take effect. Gel electrophoresis has shown that a few protein spots are changed (pI shift, appearance or disappearance of a spot) as a consequence of the application of the treatments that store or recall a meristem-production signal in flax seedlings. A SIMS investigation has revealed that the pI shift of one of these spots is probably due to protein phosphorylation. Modifications of the proteome have also been observed in Arabidopsis seedlings subjected to stimuli such as cold shock or radiation from a GSM telephone.

[Osteoporosis and inflammatory bowel disease]

Inflammatory bowel disease is a chronic disease with an unknown ethiology although multiple factors intervene such as individual, genetic and immunologic susceptibility, as well as different environmental factors. Like other multisystemic diseases, its clinical manifestations are diverse and it may affect other organs besides the gastrointestinal tract. In the last few years there is a growing interest for one of these extraintestinal manifestations, osteoporosis and osteopenia that may affect up to 42% of patients and can condition an important increase in morbility. Inactivity, prolonged corticosteroid treatment, nutritional deficiencies and the disease per se have an important role in the development of this complication. This article reviews clinical and ethiological aspects of inflammatory bowel disease associated osteoporosis and offers a strategy for diagnosis and treatment.

Possible interplay between vitamin C deficiency and prolactin in pregnant women with premature rupture of membranes: facts and hypothesis

The precise etiologic mechanisms involved in the premature rupture of membranes (PROM) during pregnancy, the main cause of preterm delivery worldwide, are unknown. Previous studies have shown that: (a) the rupture of chorioamniotic membranes is related to an imbalance between synthesis and degradation of collagen induced by the overexpression/activity of various matrix metalloproteinases (MMP); (b) during human labor and delivery the expression of prolactin receptors (PRL-R) increases in chorioamniotic membranes, decidua and placenta; (c) prolactin (PRL) can influence the synthesis of prostaglandins, the expression of some MMP (MMP-2, MMP-9 and decysin) and tissue inhibitors of MMP in general; (d) vitamin C deficiency induces the expression/activity of extracellular MMP and is considered a risk factor for PROM; and (e) vitamin C potentiates the dopamine-mediated inhibition of PRL in rats. The present hypothesis proposes that a decreased hypothalamic dopaminergic tone-and thus an increased synthesis/release of pituitary PRL - is induced by vitamin C deficiency below a critical threshold (<18 microg/10(8) leukocytes) and that both factors, in turn, would cause upregulation of the expression/activity of several MMP. The increased PRL concentrations (acting like a Th1-type cytokine) along with the overexpression of other proinflammatory cytokines would induce a premature switch from a favorable Th2-type immune response to a noxious Th1-type immune response in the intrauterine environment. This change, in conjunction with the upregulation of MMP-2 and MMP-9, would cause a premature imbalance between synthesis/degradation of collagen in chorioamniotic membranes (an "anticipation" of the normal parturition cascade?), which favors extracellular matrix degradation, proposed as the most relevant event in the genesis of PROM. This hypothesis represents a new dimension in the study of the etiology of PROM.

Can an apple a day keep the doctor away?

The modern pharmaceutical industry based on synthetic chemistry severed the historical connection between plants, food and medicines. The growing costs of discovering new chemical entity-based drugs through high throughput screening methods may yet again reconnect plants and human health at a new level of technological sophistication. Multi-component botanical therapeutics that comprise functional foods, dietary supplements and botanical drugs hold several advantages over conventional drugs that may earn them a more prominent place in the medicine of the future. They can deliver mixtures of multi-functional molecules with potentiating and synergistic effects and pleiotropic targeting at a reasonable cost and with fewer regulatory constraints. They are well suited for long-term disease prevention in an era of genetic testing and increased life expectancy. They also provide additional vehicles for delivering health and wellness. Technologies that address the needs of discovery, development and manufacturing of multi-component botanical therapeutics are emerging. They include computational and bioinformatics approaches, cell based gene expression and high-content screening systems, and phytochemical elicitation and unique plant cultivation / extraction methods designed to optimize the production of bioactives, standardize overall extract composition and assure batch-to-batch product consistency. Nevertheless, multi-component botanical therapeutics carry risks associated with potential interactions with conventional drugs and adverse reactions, which are difficult to detect and diagnose. They face problems of acceptance by the medical community and pharmaceutical industry, safety and efficacy validation, poor standardization and quality control, and difficulties in identifying active ingredients and determining their complex mode(s) of action. Solving these problems will accelerate the merger of grocery stores with pharmacies and agriculture with chemical manufacturing and provide physicians and patients with broader and more individualized choices for disease prevention and treatment.

A logical (discrete) formulation for the storage and recall of environmental signals in plants

When subjected to an appropriate asymmetric stimulus, seedlings of Bidens pilosa L. "store" a symmetry-breaking instruction that will finally take effect (in the form of a differential growth of the cotyledonary buds) only if the plants are in a state in which they can "recall" this information. The ability of the plants to recall the stored symmetry-breaking instruction may be switched "on" or "off" by the application of a variety of stimuli. Although its detailed phenomenology is rather complicated, the overall behaviour of the plant storage/recall system can be modelled by use of an asynchronous, logical (discrete) description involving positive and negative feedback circuits, which are required for the existence of multi-stationarity and stability, respectively. The state tables, as used in this formalism, give a concise and easy-to-handle description of the evolution of the system and make it particularly easy to determine its stable states. This modelling approach may be extended to the formulation of many other experimental systems.

Phloem specific expression driven by wheat dwarf geminivirus V-sense promoter in transgenic dicotyledonous species

Wheat dwarf geminivirus (WDV) is a single-stranded DNA Mastrevirus. The large intergenic region (LIR) of WDV contains cis-acting elements essential for the replication of the genome as well as for the bidirectional transcription of virus genes. The LIR was fused to the GUS (uidA) reporter gene and the WDV viral sense (V-sense) promoter activity derived from the stable integration of that promoter was analysed in transgenic dicot plants. Various dicot species were tested, including Nicotiana tabacum, Nicotiana benthamiana, Arabidopsis thaliana and Cucumis melo. The GUS activity driven by the WDV promoter was also compared to that obtained in plants transformed with the GUS gene controlled by the CaMV 35S promoter as well as two phloem-specific promoters derived from the Arabidopsis thaliana AtSUC2 and AtAHA3 genes. Histochemistry showed that the WDV V-sense promoter consistently induced an expression pattern restricted to the vascular tissues, predominantly in the phloem of all organs. This promoter exhibited levels of GUS activity comparable to that driven by AtSUC2 and AtAHA3 promoters. A vascular expression pattern was observed in the four dicots tested. This was stable during plant development and was not altered following viral infection by an unrelated geminivirus. The uses of such a promoter are discussed regarding the targeting to the phloem of molecules active against vascular pests or pathogens.

Safety and efficacy of argon plasma coagulator ablation therapy for flat colorectal adenomas

INTRODUCTION

argon-plasma coagulation (APC) has been used safely and efficaciously in multiple settings including colon polyp treatment. The aim of this study was to evaluate APC efficacy and safety in the treatment of flat colorectal adenomas.

MATERIALS AND METHODS

APC ablation was prospectively performed and evaluated in 22 consecutive patients with colorectal adenomas, 11 of which had large sessile adenomas that were treated with piecemeal polypectomy and APC ablation of residual adenomatous tissue, whereas the remaining eleven patients with flat or carpet-like adenomas were only treated with APC. The mean initial longitudinal extension of adenomas to be treated with APC was 22 mm (range, 20 to 40 mm).

RESULTS

the mean age of patients was 70 years. Adenomas were found most frequently in the rectum (50%) and cecum (23%). Complete ablation was achieved in 90.9% of adenomas. Recurrence was observed in 20% of patients, all of them in the rectum, after a mean follow-up period of 16.3 months (range, 8 to 35). All recurrences were managed satisfactorily. No major complications were seen.

CONCLUSIONS

argon plasma coagulator ablation of flat colorectal adenomas is an efficacious and safe technique, specially in the right colon, but results must be confirmed in controlled trials with a higher number of patients.

Liver transplantation for autoimmune hepatitis: fulminant versus chronic hepatitis presentation

AIMS

The aim of this study was to analyse long-term outcomes of patients with liver transplantation for autoimmune hepatitis and to determine if fulminant/subfulminant hepatic failure (FSHF) at presentation was a predictor of outcome after ortothopic liver transplantation.

PATIENTS AND METHODS

Between April 1990 and October 2002, 18 patients with autoimmune hepatitis underwent 21 liver transplants. Three patients were excluded because of coexisting causes of hepatitis. Seven patients had FSHF and eight patients had chronic disease. The initial immunosuppressive regimen was cyclosporine based in 80%, and all but one patient received steroids or azathioprine.

RESULTS

Mean age at time of transplant was 44.2+/-15.5 years. Patients were followed for 38.9+/-29.6 months. Five patients (33.3%) had seven episodes of acute rejection (two steroid-resistant). Three patients developed chronic rejection. One patient displayed histologically proven recurrent autoimmune hepatitis. Actuarial patient and graft survival rates at 1 and 5 years were 80% and 56% and 78.6% and 51%, respectively. No differences in the clinical characteristics of the patients, rates of acute or chronic rejection episodes, end biliary or arterial complications were observed between FSHF and chronic autoimmune hepatitis. The study suggests a better survival for autoimmune FSHF (P=.003).

CONCLUSIONS

Liver transplant is indicated for patients displaying autoimmune chronic liver disease and FSHF with similar clinical courses at however, patients with FSHF at presentation had better survivals.

Plants and human health in the twenty-first century

The concept of growing crops for health rather than for food or fiber is slowly changing plant biotechnology and medicine. Rediscovery of the connection between plants and health is responsible for launching a new generation of botanical therapeutics that include plant-derived pharmaceuticals, multicomponent botanical drugs, dietary supplements, functional foods and plant-produced recombinant proteins. Many of these products will soon complement conventional pharmaceuticals in the treatment, prevention and diagnosis of diseases, while at the same time adding value to agriculture. Such complementation can be accelerated by developing better tools for the efficient exploration of diverse and mutually interacting arrays of phytochemicals and for the manipulation of the plant's ability to synthesize natural products and complex proteins. This review discusses the history, future, scientific background and regulatory issues related to botanical therapeutics.

[Idiopathic cholestasis associated with progressive ductopenia in two patients with hodgkin's disease]

INTRODUCTION

Jaundice in Hodgkin's disease can be due to several causes. Ductal lesions and ductopenia, which we describe below, have rarely been reported.

CASE REPORT

We describe 2 cases of idiopathic cholestasis associated with Hodgkin's disease in which duction lesions and ductopenia were found. In one case, the ductal lesion progressed to ductopenia and the patient died from complications of her oncological disease while in the second case, outcome was favorable with improvement of cholestasis and remission of Hodgkin's lymphoma.

DISCUSSION

Ductopenia should be included in the differential diagnosis of cholestasis associated with Hodgkin's disease, for which a high degree of suspicion is required. Hodgkin's disease should be suspected when ductopenia is found.

[Regenerative potential in the organ of Corti after otic intoxication]

The auditory sensory cells are sensitive to a variety of influences such as noise, ototoxic drugs and aging. In the cochlea of mammals, the destroyed sensory cells are not replaced by new sensory cells. That leads to cochlear deafness, a frequent disease in human. Unfortunately, such auditory impairment is out of reach of treatment. The development of new therapeutic strategies in this field requires a precise knowledge of the mechanisms involved in auditory sensory cells disappearance and in organ of Corti's degeneration. The aim of our study was to characterize cellular and molecular changes in the cochlea of rats which had been intoxicated with the ototoxic antibiotic amikacin. The animals were sacrificed at different survival times during and after the antibiotic treatment and their cochleas were investigated using transmission and scanning electron microscopy and using confocal microscopy after tissue labellings with different fluorescent probes. The results revealed the existence of three periods. The first one corresponds to the disappearance of the sensory cells which die by apoptosis. During the second period, the organ of Corti undergoes a scarring process; concomitantly, a contingent of nonsensory supporting cells attempts to transdifferentiate directly into sensory cells. This process however fails, and the supporting cells never reach the status of hair cells. A general process of dedifferentiation of all the epithelial cells of the organ of Corti followed by a massive apoptosis of numerous epithelial cells and of most ganglion cells occurs during the third period. After that, the organ of Corti is definitely reduced to a simple monolayered epithelium. On the basis of these data, experimental strategies aimed i) to protect the sensory cells against apoptosis and ii) to promote sensory cell regeneration are now under study. They might have important implications in human therapy.

Secondary ion mass spectrometry imaging of the fixation of 15N-labelled NO in pollen grains

We used secondary ion mass spectrometry to image cellular targets of nitrogen oxides (widespread air pollutants) in pollen grains of birch (Betula verrucosa Ehrh.) and cockfoot (Dactylis glomerata L.). The pollen samples were exposed to air supplemented with high doses of 15NO. The pollen grains were then fixed, dehydrated using a newly developed 'vapour phase' preparation method and embedded in LRW resin. Semithin sections were then analysed. Imaging was performed in scanning mode. As usual, the two isotopes 14N and 15N were imaged as 12C14N- and 12C15N-, respectively. The isotopic percentages of 15N were quantitatively determined either by image processing or by direct analysis. We show that the preferential areas of NO fixation in the pollen cell are the sporoderm and discrete intracytoplasmic structures that we tentatively describe as globoid-like structures similar to those encountered in seeds.

Engineering pancreatic islets

Pancreatic islets are neuroendocrine organs that control blood glucose homeostasis. The precise interplay of a heterogeneous group of cell populations (beta, alpha, delta and PP cells) results in the fine-tuned release of counterbalanced hormones (insulin, glucagon, somatostatin and pancreatic polypeptide respectively). Under the premises of detailed knowledge of the physiological basis underlying this behaviour, two lines of investigation might be inferred: generating computational and operational models to explain and predict this behaviour and engineering islet cells to reconstruct pancreatic endocrine function. Whilst the former is being fuelled by new computational strategies, giving biophysicists the possibility of modelling a system in which new "emergent" properties appear, the latter is benefiting from the useful tools and strategic knowledge achieved by molecular, cell and developmental biologists. This includes using tumour cell lines, engineering islet cell precursors, knowledge of the mechanisms of differentiation, regeneration and growth and, finally, therapeutic cloning of human tissues. Gaining deep physiological understanding of the basis governing these processes is instrumental for engineering new pancreatic islets.

Long-distance transport, storage and recall of morphogenetic information in plants. The existence of a sort of primitive plant 'memory'

An asymmetrical treatment of Bidens seedlings (pricking one of the seedling cotyledons) causes the cotyledonary buds to grow asymmetrically after release of apical dominance by decapitation of the seedlings. The symmetry-breaking signal propagates within the seedlings at a rate of at least a fraction of a millimetre per second. This information may be 'stored' (STO function) within the seedlings, without taking effect, for at least 2 weeks; then the information may be 'recalled' (RCL function), thus permitting transduction of the signal into the final response (differential growth of the buds), as a consequence of subjecting the seedlings to various symmetrical or asymmetrical treatments. A similar behaviour was observed with stimuli other than pricking (including non-traumatic stimuli), with plants other than Bidens (flax, tomato), and with responses other than cotyledonary-bud growth (hypocotyl elongation, induction of meristems, thigmomorphogenesis). There are indications that storage may involve the activation of elements implicated in cell cycle control, and that the last steps of the final response involve genes such as tch1 and hsp70. The adaptive advantage for plants in possessing STO/RCL functions is discussed. Manipulating the STO/RCL functions may have interesting practical applications, e.g. in the resistance of plants to natural stresses. The existence of the STO/RCL functions in plants constitutes an elementary form of 'memory' which may provide an experimental system simpler than the animal brain to test the validity of the theoretical models of interpretation of important features such as memory storage and evocation.

Non-genomic actions of 17beta-oestradiol in mouse pancreatic beta-cells are mediated by a cGMP-dependent protein kinase

1. Intracellular calcium concentration ([Ca2+]i) was measured in mouse whole islets of Langerhans using the calcium-sensitive fluorescent dye Indo-1. 2. Application of physiological concentrations of 17beta-oestradiol in the presence of a stimulatory glucose concentration (8 mM) potentiated the [Ca2+]i signal in 83 % of islets tested. Potentiation was manifested as either an increase in the frequency or duration of [Ca2+]i oscillations. 3. The effects caused by 17beta-oestradiol were mimicked by the cyclic nucleotide analogues 8-bromoguanosine-3',5'-cyclic monophosphate (8-Br-cGMP) and 8-bromoadenosine-3',5'-cyclic monophosphate (8-Br-cAMP). 4. Direct measurements of both cyclic nucleotides demonstrated that nanomolar concentrations of 17beta-oestradiol in the presence of 8 mM glucose increased cGMP levels, yet cAMP levels were unchanged. The increment in cGMP was similar to that induced by 11 mM glucose. 5. Patch-clamp recording in intact cells showed that 8-Br-cGMP reproduced the inhibitory action of 17beta-oestradiol on ATP-sensitive K+ (KATP) channel activity. This was not a membrane-bound effect since it could not be observed in excised patches. 6. The action of 17beta-oestradiol on KATP channel activity was not modified by the specific inhibitor of soluble guanylate cyclase (sGC) LY 83583. This result indicates a likely involvement of a membrane guanylate cyclase (mGC). 7. The rapid decrease in KATP channel activity elicited by 17beta-oestradiol was greatly reduced using Rp-8-pCPT-cGMPS, a specific blocker of cGMP-dependent protein kinase (PKG). Conversely, Rp-cAMPS, which inhibits cAMP-dependent protein kinase (PKA), had little effect. 8. The results presented here indicate that rapid, non-genomic effects of 17beta-oestradiol after interaction with its binding site at the plasma membrane of pancreatic beta-cells is a cGMP-dependent phosphorylation process.

Mechanisms of glucose hypersensitivity in beta-cells from normoglycemic, partially pancreatectomized mice

Increased beta-cell sensitivity to glucose precedes the loss of glucose-induced insulin secretion in diabetic animals. Changes at the level of beta-cell glucose sensor have been described in these situations, but it is not clear whether they fully account for the increased insulin secretion. Using a euglycemic-normolipidemic 60% pancreatectomized (60%-Px) mouse model, we have studied the ionic mechanisms responsible for increased beta-cell glucose sensitivity. Two weeks after Px (Px14 group), Px mice maintained normoglycemia with a reduced beta-cell mass (0.88 +/- 0.18 mg) compared with control mice (1.41 +/- 0.21 mg). At this stage, the dose-response curve for glucose-induced insulin release showed a significant displacement to the left (P < 0.001). Islets from the Px14 group showed oscillatory electrical activity and cytosolic Ca2+ ([Ca2+]i) oscillations in response to glucose concentrations of 5.6 mmol/l compared with islets from the control group at 11.1 mmol/l. All the above changes were fully reversible both in vitro (after 48-h culture of islets from the Px14 group) and in vivo (after regeneration of beta-cell mass in islets studied 60 days after Px). No significant differences in the input resistance and ATP inhibition of ATP-sensitive K+ (K(ATP)) channels were found between beta-cells from the Px14 and control groups. The dose-response curve for glucose-induced MTT (C,N-diphenyl-N''-4,5-dimethyl thiazol 2 yl tetrazolium bromide) reduction showed a significant displacement to the left in islets from the Px14 group (P < 0.001). These results indicate that increased glucose sensitivity in terms of insulin secretion and Ca2+ signaling was not due to intrinsic modifications of K(ATP) channel properties, and suggest that the changes are most likely to be found in the glucose metabolism.