Pyruvate dehydrogenase (PDH) is poorly active in circulating lymphocytes of NIDDM patients; in vitro, it is unresponsive to insulin at 5 microU/ml and activated at 50 microU/ml, instead of activated ...and inhibited as in healthy controls. This study examines whether healthy offspring of NIDDM patients with a family history for this disease have these alterations. Twenty seven healthy offspring (23+/-10 yr, median 18 yr) and their parents (13 diabetic with a family history for NIDDM and 11 healthy without this history) were enrolled. Twenty healthy individuals without the history and matched for age and gender with the offspring served as controls. Minimum levels for enzyme activity before and after cell stimulation with insulin at 5 microU/ml were computed for a 95% CI with no more than 5% of the controls excluded. Increased or unvaried enzyme activity in response to insulin at 50 microU/ml was defined as abnormal. All NIDDM parents and 11/27 offspring had below normal enzyme activity and defective and reversed enzyme response to insulin at 5 and 50 microU/ml; three offspring had altered enzyme response to insulin at both concentrations, four to insulin at 5 microU/ml, three to insulin at 50 microU/ml and six, together with the healthy parents, had no alterations. We conclude that in healthy individuals a family history for NIDDM is frequently signaled, irrespective of age, by molecular derangements, with an apparent genetic background, in their circulating lymphocytes.
Adult‐onset dominant leukodystrophies are a heterogeneous group of rare disorders, whose etiology, pathogenesis and molecular background are still unknown. We report the neuropathological and ...biochemical investigations of the brains and their myelin proteins components in 2 members of an Italian family affected by an adult‐onset autosomal dominant leukoencephalopathy. Clinical signs included spastic paraparesis, pseudobulbar syndrome, action tremor of head and hands, and moderate memory impairment. No mental deterioration or neuropathy was present. Onset was subacute (range 42–53 years) and progression spanned 4 to 7 years. The neuropathological phenotype overlapped that of orthochromatic leukodystrophies. The biochemical analysis revealed an abnormal myelin‐associated glycoprotein (MAG); the defect was localized at the C‐terminal domain of the L‐MAG isoform, resulting in a protein approximately 5 kDa shorter than the normal counterpart. No mutation in the MAG gene‐coding regions was uncovered, and linkage analysis formally excluded the entire MAG locus. We show that the identified MAG protein alteration is probably due to an abnormal post‐translational event. Considering MAG function in the maintenance of myelin, the abnormal protein may have a role in the pathogenesis of this disease. This is the first report of a possible pathogenetic role of MAG in a hereditary disease affecting the central white matter.
This paper proposes and analyzes three policy instruments which can be used to enhance farmers' compliance with individual water allocations in a decentralized management context. Three regulation ...strategies are proposed for the case of groundwater allocations for irrigation: the first relies on economic instruments; the second is based on tools designed to promote pro-social behaviors; and the third combines assumptions from the first two approaches. They are evaluated through 16 scenario workshops involving 124 stakeholders and farmers in five French groundwater basins. Stakeholders' perceptions are analyzed, disentangling the ethical, economic, institutional, social and technical perspectives underlying the stakeholders' arguments for or against the proposed instruments for groundwater-use regulation. The analysis reveals a preference for the strategy that combines economic and social incentives.
•Three regulatory strategies were designed, combining economic and social incentives.•16 scenario workshops were carried out involving 124 stakeholders in five French groundwater basins.•Economic incentives may be efficient if well designed, but they find little acceptance.•Social incentives are acceptable but their effectiveness depends on pre-existing community cohesion.•Participatory evaluation methodologies enable the integrated evaluation of environmental policies.
In circulating lymphocytes of individuals with insulin resistance and overt hyperglycaemia (NIDDM patients), alterations, affecting pyruvate dehydrogenase (PDH), the key enzyme in glucose oxidative ...breakdown, have been observed. They include below normal enzyme activity and, in vitro, no enzyme response to insulin at low physiological levels (5 microU/ml) as well as activation up to the basal values of controls with insulin at high physiological levels (50 microU/ml), instead of activation and inhibition respectively, as in controls.
To investigate whether these alterations characterize circulating lymphocytes of individuals with insulin resistance in whom derangements of glucose homeostasis are absent (obese subjects with normal glucose tolerance), or present but still controllable (nonobese and obese newly diagnosed NIDDM patients on an appropriate diet).
Thirty obese subjects (BMI 36 +/- 3) responding normally to an oral glucose tolerance (OGT) test; 60 newly diagnosed NIDDM patients (30 nonobese, BMI 22 +/- 4 and 30 obese, BMI 38 +/- 2); 30 nonobese (BMI 21 +/- 5) and nondiabetic subjects, with no family history for NIDDM, served as controls.
Evaluation of PDH activity in circulating lymphocytes before and after exposure to insulin at 5 and 50 microU/ml, and of clinical parameters before and during an OGT test.
1) in circulating lymphocytes of obese nondiabetic subjects as well as obese and nonobese newly diagnosed NIDDM patients, PDH activity was significantly below normal. In vitro, enzyme response to insulin at 5 microU/ml was reduced in nonobese NIDDM patients with respect to controls, and absent in obese nondiabetic subjects and obese NIDDM patients. Enzyme response to insulin at 50 microU/ml was reversed in all individuals, which allowed enzyme activity to recover up to the basal level of controls. 2) In NIDDM patients and obese nondiabetic subjects, undergoing an OGT test, the area under the glycaemic curve (g-AUC) was as expected; the area under the insulinaemic curve (i-AUC) was increased in both groups with respect to controls, but significantly only in the latter.
In individuals with insulin resistance PDH activity in their circulating lymphocytes rises up to basal levels of controls, only if these cells are exposed to insulin at high physiological concentrations, and g-AUC is normal only in those subjects who have significantly increased i-AUC. This suggests that with insulin at sufficiently high concentrations both parameters can be corrected. We conclude that the derangements responsible for the alterations of the two parameters share common features and thus the described PDH alterations in circulating lymphocytes reflect systemic insulin resistance whether accompanied by hyperglycaemia or not.
Gellan is an anionic extracellular bacterial polysaccharide discovered in 1978. Acyl groups present in the native polymer are removed by alkaline hydrolysis in normal commercial production, giving ...the charged tetrasaccharide repeating sequence: → 3)-β-d-Glcp-(1 → 4)-β-d-GlcpA-(1 → 4)-β-d-Glcp-(1 → 4)-α-l-Rhap-(1 →. Deacylated gellan converts on cooling from disordered coils to 3-fold double helices. The coil–helix transition temperature (Tm) is raised by salt in the way expected from polyelectrolyte theory: equivalent molar concentrations of different monovalent cations (Group I and Me4N+) cause the same increase in Tm; there is also no selectivity between different divalent (Group II) cations, but divalent cations cause greater elevation of Tm than monovalent. Cations present as counterions to the charged groups of the polymer have the same effect as those introduced by addition of salt. Increasing polymer concentration raises Tm because of the consequent increase in concentration of the counterions, but the concentration of polymer chains themselves does not affect Tm. Gelation occurs by aggregation of double helices. Aggregation stabilises the helices to temperatures higher than those at which they form on cooling, giving thermal hysteresis between gelation and melting. Melting of aggregated and non-aggregated helices can be seen as separate thermal and rheological processes. Reduction in pH promotes aggregation and gelation by decreasing the negative charge on the polymer and thus decreasing electrostatic repulsion between the helices. Group I cations decrease repulsion by binding to the helices in specific coordination sites around the carboxylate groups of the polymer. Strength of binding increases with increasing ionic size (Li+ < Na+ < K+ < Rb+ < Cs+); the extent of aggregation and effectiveness in promoting gel formation increase in the same order. Me4N+ cations, which cannot form coordination complexes, act solely by non-specific screening of electrostatic repulsion, and give gels only at very high concentration (above ∼0.6 M). At low concentrations of monovalent cations, ordered gellan behaves like a normal polymer solution; as salt concentration is increased there is then a region where fluid “weak gels” are formed, before the cation concentration becomes sufficient to give true, self-supporting gels. Aggregation and consequent gelation with Group II cations occurs by direct site-binding of the divalent ions between gellan double helices. High concentrations of salt or acid cause excessive aggregation, with consequent reduction in gel strength. Maximum strength with divalent cations comes at about stoichiometric equivalence to the gellan carboxylate groups. Much higher concentrations of monovalent cations are required to attain maximum gel strength. The content of divalent cations in commercial gellan is normally sufficient to give cohesive gels at polymer concentrations down to ∼0.15 wt %. Gellan gels are very brittle, and have excellent flavour release. The networks are dynamic: gellan gels release polymer chains when immersed in water and show substantial recovery from mechanical disruption or expulsion of water by slow compression. High concentrations of sugar (∼70 wt % and above) inhibit aggregation and give sparingly-crosslinked networks which vitrify on cooling. Gellan forms coupled networks with konjac glucomannan and tamarind xyloglucan, phase-separated networks with kappa carrageenan and calcium alginate, interpenetrating networks with agarose and gelling maltodextrin, and complex coacervates with gelatin under acidic conditions. Native gellan carries acetyl and l-glyceryl groups at, respectively, O(6) and O(2) of the 3-linked glucose residue in the tetrasaccharide repeat unit. The presence of these substituents does not change the overall double helix structure, but has profound effects on gelation. l-Glyceryl groups stabilise the double helix by forming additional hydrogen bonds within and between the two strands, giving higher gelation temperatures, but abolish the binding site for metal ions by changing the orientation of the adjacent glucuronate residue and its carboxyl group. The consequent loss of cation-mediated aggregation reduces gel strength and brittleness, and eliminates thermal hysteresis. Aggregation is further inhibited by acetyl groups located on the periphery of the double helix. Gellan with a high content of residual acyl groups is available commercially as “high acyl gellan”. Mixtures of high acyl and deacylated gellan form interpenetrating networks, with no double helices incorporating strands of both types. Gellan has numerous existing and potential practical applications in food, cosmetics, toiletries, pharmaceuticals and microbiology.
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Many regions around the world are transitioning out of open access to groundwater resources in order to tackle over extraction by irrigated agriculture. However, the state has limited capacities to ...regulate effectively agricultural groundwater use. This paper evaluates how users and public authorities can co‐manage groundwater extraction by agriculture. Based on Schlager and Ostrom’s “bundle of rights” framework, the paper examines how decisions over access and use of groundwater resources are made in France, Spain and California. The three cases share a common strive to involve groundwater users in decisions over how to reduce over extraction of groundwater resources. However, different choices were made regarding the institutional set‐up for user involvement in allocation decisions. The paper presents the diversity of institutional arrangements influencing groundwater allocations in the three cases, and the relative involvement and power of users and public authorities over these institutions. The papers show the different ways in which “comanagement” may be made operational for managing agricultural groundwater use.
Key Points
The paper presents institutional mechanisms influencing allocation decisions in agriculture in France, Spain, and California
An evolution is observed toward greater oversight over operational rights of accessing and withdrawing groundwater
A system of check‐and‐balances are needed to ensure that all three sustainability pillars (economic, social, environmental) are met
BACKGROUND: Circulating lymphocytes of obese individuals with and without type 2 diabetes have derangements of pyruvate dehydrogenase (PDH) that are described as reflecting a disorder underlying ...systemic insulin resistance, namely basal activity below normal and, in vitro, unresponsiveness to insulin at 33 pmol/l and activation at 330 pmol/l instead of activation and inhibition as in controls. OBJECTIVE: To explore whether the above enzyme derangements are overcome in obese individuals on dexfen-fluramine treatment, known to improve poor peripheral insulin sensitivity. METHODS: Fifteen obese diabetic patients and 15 age-matched euglycaemic obese subjects with normal glucose tolerance were enrolled for a trial composed of two 21-day periods; in the first (D-21-D0), participants received a placebo, and in the second (D0-D21), dexfenfluramine (30 mg/day). At D-21, D0 and D21 participants were evaluated for weight, BMI, fasting glycaemia (FG), fasting insulinaemia (FI), fasting insulin resistance index (FIRI), area under the glycaemic (G-AUC) and insulinaemic (I-AUC) curves from an OGT test, and for PDH activity assayed in their circulating lymphocytes before (basal activity) and after incubation with 33 or 330 pmol/l insulin. At D2, basal PDH activity and clinical parameters were assayed. RESULTS: In both groups of participants at D0 all parameters tested were constant with respect to D-21; at D2, only basal PDH activity rose significantly; at D21, basal and insulin stimulated PDH activities were normalized and weight decreased significantly, as did FG, FI, FIRI and G-AUC in the diabetic, and FI, FIRI, G-AUC and I-AUC in the non-diabetic participants. CONCLUSION: In obese, non-diabetic and diabetic individuals on dexfenfluramine treatment, amelioration of clinical parameters and indexes of poor insulin sensitivity of blood glucose homeostasis are preceded by correction, in their circulating lymphocytes, of PDH derangements described as reflecting a disorder underlying insulin resistance.
OBJECTIVE: The objective of this study was to determine whether down-regulation of pyruvate dehydrogenase phosphatase (PDP) is responsible for poorly active pyruvate dehydrogenase (PDH) in ...circulating lymphocytes (CLs) of obese subjects (ObS), and if so, whether it improves when their plasma insulin rises. RESEARCH METHODS AND PROCEDURES: PDH activity was compared in lysed CLs of 10 euglycemic ObS and 10 sex- and age-matched controls before and during plasma insulin enhancement in an oral glucose tolerance test. It was evaluated without (PDHa) or with Mg/Ca or Mg at various concentrations to assess PDP1 or PDP2 activities or with Mg/Ca and exogenous PDP to determine total PDH activity (PDHt), which is an indirect measure of the amount of PDH. The insulin sensitivity index was calculated, and PDP1 and PDP2 mRNA was sought in the CLs. RESULTS: At T₀ in ObS, PDHt was normal, whereas PDHa and PDP1 activity was below normal at all Mg/Ca concentrations. PDP2 activity was undetectable in both groups. PDP1 and PDP2 mRNA was identified, and insulin sensitivity index and PDHa were directly correlated. During the oral glucose tolerance test, plasma insulin rose considerably more in ObS than in controls; PDHa and PDP1 activity also increased but remained significantly below normal, and PDHt was unvaried in both groups. DISCUSSION: PDP1 is down-regulated in CLs of ObS because it is poorly sensitive to Mg/Ca; this defect is attenuated when plasma insulin is greatly enhanced.
Proteasomes as drug targets Piccinini, Marco; Mostert, Michael; Rinaudo, Maria Teresa
Current drug targets,
11/2003, Letnik:
4, Številka:
8
Journal Article
Recenzirano
The ubiquitin-proteasome pathway plays a role in the degradation of the bulk of proteins in the cytoplasmic and nuclear compartments. In this pathway proteins are targeted for degradation by covalent ...ligation with ubiquitin, a reaction that requires ATP. Following the binding of the first ubiquitin molecule with the epsilon-amino group of a lysine residue of the substrate protein, a polyubiquitin chain is usually formed, in which the C-terminus of each ubiquitin unit is linked to a specific Lys residue of the previous ubiquitin. Central to this pathway is the 26S proteasome, a high molecular mass multifunctional protease which requires ATP for its catalytic activity. Substrates of the 26S proteasome are not only old or damaged proteins, but also short lived proteins functioning as regulatory factors in a large array of cellular processes, such as cell cycle progression, cell growth and gene expression, inflammatory response and immune surveillance. A number of inhibitors of the catalytic activity of proteasomes have been developed and successfully employed in the study of their functional and structural properties, as well as of their involvement in different cellular processes. Some of these molecules due to their toxicity are used only as experimental research tools; others instead are now in clinical trials for treatment of a variety of hematologic malignancies and solid tumors and of reperfusion injury occurring after cerebral ischemia and myocardial infarction. Furthermore, proteasome inhibitors are described to interfere with HIV maturation, budding and aggressiveness, and cytostatic drugs, as well as antiretroviral agents used in HAART, have been shown to behave in vitro and in cultured cell lines as inhibitors of proteasome proteolytic activity at therapeutic dosages.
Several decision algorithms based on the measurement of infliximab (IFX) trough levels and antibodies to IFX have been proposed. Whether such algorithms can be extrapolated to the pharmacokinetics of ...adalimumab (ADA) has yet to be determined.
A prospective study included all consecutive patients with inflammatory bowel disease (IBD) having a disease flare while being on ADA 40 mg every 2 weeks were included. All patients were primary responders to ADA therapy and were anti-tumor necrosis factor (TNF) naive. ADA trough levels and antibodies against ADA (AAA) were measured blinded to clinical data (Elisa LISA-Tracker, Theradiag). All patients were optimized with ADA 40 mg weekly. Four months later, in the absence of clinical remission (CR; Crohn's disease activity index <150 for Crohn's disease (CD), and Mayo score <2 for ulcerative colitis), patients were treated with IFX therapy. Patients were divided into three groups based on ADA trough levels and based on previous studies: group A, ADA>4.9 μg/ml; group B, ADA<4.9 μg/ml and undetectable levels of AAA (<10 ng/ml); and group C, ADA<4.9 μg/ml and AAA >10 ng/ml.
A total of 82 patients were included (55% CD; mean age=43 years, disease duration=7.4 years, duration of ADA therapy=17 months). After optimization of ADA treatment, 29.2% of patients achieved CR in group A (N=41), 67% in group B (N=24), and 12% in group C (N=17; P<0.01 between groups A/B and B/C). C-reactive protein level at the time of relapse, disease duration, duration of ADA therapy, and IBD type was not predictive of CR after ADA optimization by univariate analysis. The response to ADA optimization was significantly more durable in group B (15 months) than in groups A and C (4 and 5 months, respectively). Fifty-two patients who failed following ADA optimization (63%) were treated with IFX, and 30.6% of them achieved CR. CR rates following IFX initiation were 6.9%, 25%, and 80% in groups A, B, and C, respectively (P<0.01 between groups C/A and between groups C/B). Duration of response to IFX was significantly higher in group C than in groups A and B (14 vs. 3 and 5 months, respectively, P<0.01).
The presence of low ADA trough levels without AAA is strongly predictive of clinical response in 67% of cases after ADA optimization. Conversely, low ADA levels with detectable AAA are associated with ADA failure, and switching to IFX should be considered. ADA trough levels >4.9 μg/ml are associated with failure of two anti-TNF agents (ADA and IFX) in 90% of cases, and switching to another drug class should be considered.
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