The importance and effect of dietary fiber in diabetes prevention with particular consideration of whole grain products.

The state of prediabetes is characterized by an increase in insulin resistance and a decrease in pancreatic beta cell function. The prestage of type 2 diabetes mellitus can be identified by an impaired glucose tolerance and/or by an impaired fasting blood sugar. Apart from weight loss and increase in physical activity, the development of type 2 diabetes mellitus can also be prevented by dietary changes. A low-fat diet with a dietary fiber intake of more than 30g/d was shown to represent an effective preventive approach. A high-fiber diet has many positive effects on the physical health status. In addition to positive effects in the gastrointestinal tract it has an obvious potential to support weight reduction and to improve disturbances of carbohydrate and fat metabolism. At the present state of knowledge, insoluble dietary fibers as found in whole grain cereal products are considered to be especially effective in the prevention of type 2 diabetes mellitus. A high intake of fruits and vegetables as well as pulses also exerts health-promoting properties. A high-fiber diet also plays an important role in the prevention of obesity and coronary heart diseases.     

Autophagy and cell death: no longer at odds

Autophagy has been associated with both cell survival and cell death, but the role of autophagy in cell death has been controversial. In this issue, Berry and Baehrecke (2007) report that autophagy is involved in physiological cell death during Drosophila development and is controlled by similar mechanisms as those that control its function in cell survival.     

Dual selection pressure by drugs and HLA class I-restricted immune responses on human immunodeficiency virus type 1 protease

To determine the influence of human immunodeficiency virus type 1 (HIV-1)-specific CD8+ T cells on the development of drug resistance mutations in the HIV-1 protease, we analyzed protease sequences from viruses from a human leukocyte antigen class I (HLA class I)-typed cohort of 94 HIV-1-positive individuals. In univariate statistical analyses (Fisher's exact test), minor and major drug resistance mutations as well as drug-associated polymorphisms showed associations with HLA class I alleles. All correlations with P values of 0.05 or less were considered to be relevant without corrections for multiple tests. A subset of these observed correlations was experimentally validated by enzyme-linked immunospot assays, allowing the definition of 10 new epitopes recognized by CD8+ T cells from patients with the appropriate HLA class I type. Several drug resistance-associated mutations in the protease acted as escape mutations; however, cells from many patients were still able to generate CD8+ T cells targeting the escape mutants. This result presumably indicates the usage of different T-cell receptors by CD8+ T cells targeting these epitopes in these patients. Our results support a fundamental role for HLA class I-restricted immune responses in shaping the sequence of the HIV-1 protease in vivo. This role may have important clinical implications both for the understanding of drug resistance pathways and for the design of therapeutic vaccines targeting drug-resistant HIV-1.     

Translation elongation factor eEF1A2 is essential for post-weaning survival in mice

Translation elongation factor eEF1A, formerly known as EF-1 alpha, exists as two variant forms; eEF1A1, which is almost ubiquitously expressed, and eEF1A2, whose expression is restricted to muscle and brain at the level of whole tissues. Expression analysis of these genes has been complicated by a general lack of availability of antibodies that specifically recognize each variant form. Wasted mice (wst/wst) have a 15.8-kilobase deletion that abolishes activity of eEF1A2, but before this study it was unknown whether the deletion also affected neighboring genes. We have generated a panel of anti-peptide antibodies and used them to show that eEF1A2 is expressed at high levels in specific cell types in tissues previously thought not to express this variant, such as pancreatic islet cells and enteroendocrine cells in colon crypts. Expression of eEF1A1 and eEF1A2 is shown to be generally mutually exclusive, and we relate the expression pattern of eEF1A2 to the phenotype seen in wasted mice. We then carried out a series of transgenic experiments to establish whether the expression of other genes is affected by the deletion in wasted mice. We show that aspects of the phenotype such as motor neuron degeneration relate precisely to the relative expression of eEF1A1 and eEF1A2, whereas the immune system abnormalities are likely to result from a stress response. We conclude that loss of eEF1A2 function is solely responsible for the abnormalities seen in these mice.     

In vivo glenohumeral contact forces--measurements in the first patient 7 months postoperatively

Knowledge of forces in the glenohumeral joint is essential for understanding normal and pathologic shoulder function. It forms the basis for performing fracture treatment or joint replacement surgery, for optimizing implant design and fixation and for improving and verifying analytical biomechanical models of the shoulder. An instrumented shoulder implant with telemetric data transmission was developed to measure six components of joint contact forces and moments. A patient with humeral head arthrosis achieved good joint function after its implantation. During the first 7 postoperative months, the contact force remained below 100% BW (percent body weight) for most activities of daily living. It ranged up to 130% BW for arm positions close to the limits of motion or when acting against external resistance. When the patient tried to turn a blocked steering wheel with maximum effort, the force rose to about 150% BW, the highest level observed thus far. Of great interest were the force directions relative to the humerus, especially those in the sagittal plane, which were not greatly influenced by the type of exercise, the arm position or the external resistance. The moments due to friction in the joint reached 5.2 Nm. The friction-induced shift of contact forces relative to the implant head centre ranged up to 6.3mm. These first worldwide in vivo measurements of glenohumeral contact forces are being continued in more patients and for longer postoperative times.     

Synthesis and radiopharmacological characterization of 2beta-carbo-2'-[18F]fluoroethoxy-3beta-(4-bromo-phenyl)tropane ([18F]MCL-322) as a PET radiotracer for imaging the dopamine transporter (DAT)

The fluoroalkyl-containing tropane derivative 2beta-carbo-2'-fluoroethoxy-3beta-(4-bromo-phenyl)tropane (MCL-322) is a highly potent and moderately selective ligand for the dopamine transporter (DAT). The compound was labeled with the short-lived positron emitter (18)F in a single step by nucleophilic displacement of the corresponding tosylate precursor MCL-323 with no-carrier-added [(18)F]fluoride. The positron emission tomography (PET) radiotracer 2beta-carbo-2'-[(18)F]fluoroethoxy-3beta-(4-bromo-phenyl)tropane [(18)F]MCL-322 was obtained in decay-corrected radiochemical yields of 30-40% at a specific radioactivity of 1.6-2.4Ci/mumol (60-90GBq/mumol) at the end-of-synthesis (EOS). Small animal PET, ex vivo and in vivo biodistribution experiments in rats demonstrated a high uptake in the striatum (3.2% ID/g) 5min after injection, which increased to 4.2% ID/g after 60min. The uptake in the cerebellum was 1.8% ID/g and 0.6% ID/g after 5min and 60min post-injection, respectively. Specific binding to DAT of [(18)F]MCL-322 was confirmed by blocking experiments using the high affinity DAT ligand GBR 12909. The radiopharmacological characterization was completed with metabolite and autoradiographic studies confirming the selective uptake of [(18)F]MCL-322 in the striatum. It is concluded that the simple single-step radiosynthesis of [(18)F]MCL-322 and the promising radiopharmacological data make [(18)F]MCL-322 an attractive candidate for the further development of a PET radiotracer potentially suitable for clinical DAT imaging in the human brain.     

Dynamics of electron transfer in photosystem II

Photosystem II, being a constituent of light driven photosynthetic apparatus, is a highly organized pigment-protein-lipid complex. The arrangement of PSII active redox cofactors insures efficiency of electron transfer within it. Donation of electrons extracted from water by the oxygen evolving complex to plastoquinones requires an additional activation energy. In this paper we present theoretical discussion of the anharmonic fluctuations of the protein-lipid matrix of PSII and an experimental evidence showing that the fluctuations are responsible for coupling of its donor and acceptor side. We argue that the fast collective motions liberated at temperatures higher that 200 K are crucial for the two final steps of the water splitting cycle and that one can distinguish three different dynamic regimes of PSII action which are controlled by the timescales of forward electron transfer, which vary with temperature. The three regimes of the dynamical behavior are related to different spatial domains of PSII.     

A polygalacturonase-inhibiting protein from grapevine reduces the symptoms of the endopolygalacturonase BcPG2 from Botrytis cinerea in Nicotiana benthamiana leaves without any evidence for in vitro interaction

Six endopolygalacturonases from Botrytis cinerea (BcPG1 to BcPG6) as well as mutated forms of BcPG1 and BcPG2 were expressed transiently in leaves of Nicotiana benthamiana using agroinfiltration. Expression of BcPG1, BcPG2, BcPG4, BcPG5, and mutant BcPG1-D203A caused symptoms, whereas BcPG3, BcPG6, and mutant BcPG2-D192A caused no symptoms. Expression of BcPG2 caused the most severe symptoms, including wilting and necrosis. BcPG2 previously has been shown to be essential for B. cinerea virulence. The in vivo effect of this enzyme and the inhibition by a polygalacturonase-inhibiting protein (PGIP) was examined by coexpressing Bcpg2 and the Vvpgipl gene from Vitis vinifera in N. benthamiana. Coinfiltration resulted in a substantial reduction of the symptoms inflicted by the activity of BcPG2 in planta, as evidenced by quantifying the variable chlorophyll fluorescence yield. In vitro, however, no interaction between pure VvPGIP1 and pure BcPG2 was detected. Specifically, VvPGIP1 neither inhibited BcPG2 activity nor altered the degradation profile of polygalacturonic acid by BcPG2. Furthermore, using surface plasmon resonance technology, no physical interaction between VvPGIP1 and BcPG2 was detected in vitro. The data suggest that the in planta environment provided a context to support the interaction between BcPG2 and VvPGIP1, leading to a reduction in symptom development, whereas neither of the in vitro assays detected any interaction between these proteins.