Effect of intermittent fasting and refeeding on insulin action in healthy men.

Insulin resistance is currently a major health problem. This may be because of a marked decrease in daily physical activity during recent decades combined with constant food abundance. This lifestyle collides with our genome, which was most likely selected in the late Paleolithic era (50,000-10,000 BC) by criteria that favored survival in an environment characterized by fluctuations between periods of feast and famine. The theory of thrifty genes states that these fluctuations are required for optimal metabolic function. We mimicked the fluctuations in eight healthy young men [25.0 +/- 0.1 yr (mean +/- SE); body mass index: 25.7 +/- 0.4 kg/m(2)] by subjecting them to intermittent fasting every second day for 20 h for 15 days. Euglycemic hyperinsulinemic (40 mU.min(-1).m(-2)) clamps were performed before and after the intervention period. Subjects maintained body weight (86.4 +/- 2.3 kg; coefficient of variation: 0.8 +/- 0.1%). Plasma free fatty acid and beta-hydroxybutyrate concentrations were 347 +/- 18 and 0.06 +/- 0.02 mM, respectively, after overnight fast but increased (P < 0.05) to 423 +/- 86 and 0.10 +/- 0.04 mM after 20-h fasting, confirming that the subjects were fasting. Insulin-mediated whole body glucose uptake rates increased from 6.3 +/- 0.6 to 7.3 +/- 0.3 mg.kg(-1).min(-1) (P = 0.03), and insulin-induced inhibition of adipose tissue lipolysis was more prominent after than before the intervention (P = 0.05). After the 20-h fasting periods, plasma adiponectin was increased compared with the basal levels before and after the intervention (5,922 +/- 991 vs. 3,860 +/- 784 ng/ml, P = 0.02). This experiment is the first in humans to show that intermittent fasting increases insulin-mediated glucose uptake rates, and the findings are compatible with the thrifty gene concept.     

Atlantic salmon (Salmo salar) muscle precursor cells differentiate into osteoblasts in vitro: Polyunsaturated fatty acids and hyperthermia influence gene expression and differentiation

The formation and mineralisation of bone are two critical processes in fast-growing Atlantic salmon (Salmo salar). The mechanisms of these processes, however, have not been described in detail. Thus, in vitro systems that allow the study of factors that influence bone formation in farmed Atlantic salmon are highly warranted. We describe here a method by which unspecialised primary cells from salmon white muscle can differentiate to osteoblasts in vitro. We have subsequently used the differentiated cells as a model system to study the effects of two factors that influence bone formation in Atlantic salmon under commercial farming conditions, namely polyunsaturated fatty acids, PUFAs, and temperature. Muscle precursor cells changed their morphology from triangular or spindle-shaped cells to polygonal or cubical cells after 3 weeks in osteogenic medium. In addition, gene expression studies showed that marker genes for osteoblastogenesis; alp, col1a1, osteocalcin, bmp2 and bmp4 increased after 3 weeks of incubation in osteogenic media showing that these cells have differentiated to osteoblasts at this stage. Adding CLA or DHA to the osteoblast media resulted in a reduced PGE₂ production and increased expression of osteocalcin. Further, temperature studies showed that differentiating osteoblasts are highly sensitive to increased incubation temperature at early stages of differentiation. Our studies show that unspecialised precursor cells isolated from salmon muscle tissue can be caused to differentiate to osteoblasts in vitro. Furthermore, this model system appears to be suitable for the study of osteoblast biology in vitro.     

Comparative Pathogenesis of Alkhumra Hemorrhagic Fever and Kyasanur Forest Disease Viruses in a Mouse Model

Kyasanur Forest disease virus (KFDV) and Alkhumra hemorrhagic fever virus (AHFV) are genetically closely-related, tick-borne flaviviruses that cause severe, often fatal disease in humans. Flaviviruses in the tick-borne encephalitis (TBE) complex typically cause neurological disease in humans whereas patients infected with KFDV and AHFV predominately present with hemorrhagic fever. A small animal model for KFDV and AHFV to study the pathogenesis and evaluate countermeasures has been lacking mostly due to the need of a high biocontainment laboratory to work with the viruses. To evaluate the utility of an existing mouse model for tick-borne flavivirus pathogenesis, we performed serial sacrifice studies in BALB/c mice infected with either KFDV strain P9605 or AHFV strain Zaki-1. Strikingly, infection with KFDV was completely lethal in mice, while AHFV caused no clinical signs of disease and no animals succumbed to infection. KFDV and high levels of pro-inflammatory cytokines were detected in the brain at later time points, but no virus was found in visceral organs; conversely, AHFV Zaki-1 and elevated levels of cytokines were found in the visceral organs at earlier time points, but were not detected in the brain. While infection with either virus caused a generalized leukopenia, only AHFV Zaki-1 induced hematologic abnormalities in infected animals. Our data suggest that KFDV P9605 may have lost its ability to cause hemorrhagic disease as the result of multiple passages in suckling mouse brains. However, likely by virtue of fewer mouse passages, AHFV Zaki-1 has retained the ability to replicate in visceral organs, cause hematologic abnormalities, and induce pro-inflammatory cytokines without causing overt disease. Given these striking differences, the use of inbred mice and the virus passage history need to be carefully considered in the interpretation of animal studies using these viruses.     

The suicide assessment scale: Psychometric properties of a Norwegian language version

ABSTRACT: BACKGROUND: Rating scales are valuable tools in suicide research and can also be useful supplements to the clinical interview in suicide risk assessments. This study describes the psychometric properties of a Norwegian language version of the Suicide Assessment Scale Self-report version (SUAS-S). METHODS: Participants were fifty-two patients (mean age = 39.3 years, SD = 10.7) with major depression (53.8%), bipolar disorder (25.0%) and/or a personality disorder (63.5%) referred to a psychiatric outpatient clinic. The SUAS-S, the screening section of the Beck Scale for Suicidal Ideation (BSS-5), the Beck Depression Inventory (BDI), Beck's Hopelessness Scale (BHS), the Symptom Check-List-90 R (SCL-90R) and the Clinical Global Impression for Severity of Suicidality (CGI-SS) were administered. One week later, the patients completed the SUAS-S a second time. RESULTS: Cronbach's alpha for SUAS-S was 0.88 and the test-retest reliability was 0.95 (95% CI: 0.93- 0.97). SUAS-S was positively correlated with the BSS-5 (r = 0.66; 95% CI: 0.47-0.85) for the study sample as a whole and for the suicidal (r = 0.52) and non-suicidal groups (r = 0.50) respectively. There was no difference between the SUAS-S and the BSS-5 in the ability to identify suicidality. This ability was more pronounced when the suicide risk was high. There was a substantial intercorrelation between the score on the SUAS-S and the BDI (0.81) and the BHS (0.76). The sensitivity and specificity of the SUAS-S was explored and an appropriate clinical cut-off value was assessed. CONCLUSIONS: The study revealed good internal consistency, test-retest reliability and concurrent validity for the Suicide Assessment Scale Self-report version. The discriminatory ability for suicidality was comparable to that of the BSS-5.     

High-Affinity Interaction of the K-Ras4B Hypervariable Region with the Ras Active Site

Ras proteins are small GTPases that act as signal transducers between cell surface receptors and several intracellular signaling cascades. They contain highly homologous catalytic domains and flexible C-terminal hypervariable regions (HVRs) that differ across Ras isoforms. KRAS is among the most frequently mutated oncogenes in human tumors. Surprisingly, we found that the C-terminal HVR of K-Ras4B, thought to minimally impact the catalytic domain, directly interacts with the active site of the protein. The interaction is almost 100-fold tighter with the GDP-bound than the GTP-bound protein. HVR binding interferes with Ras-Raf interaction, modulates binding to phospholipids, and slightly slows down nucleotide exchange. The data indicate that contrary to previously suggested models of K-Ras4B signaling, HVR plays essential roles in regulation of signaling. High affinity binding of short peptide analogs of HVR to K-Ras active site suggests that targeting this surface with inhibitory synthetic molecules for the therapy of KRAS-dependent tumors is feasible.     

Effect of physical training on glucose transporters in fat cell fractions

Physical training increases maximally insulin-stimulated glucose assimilation and 3-O-methylglucose transport in epididymal fat cells. In the present report, glucose-inhibitable cytochalasin B binding in subcellular fractions of epididymal adipocytes was measured to assess changes in number of glucose transporters induced by training. Groups of rats trained by swimming were compared to control groups of the same age, matched with respect to body weight by restricted feeding. It was found that in trained rats the number of glucose transporters in the low density microsome fractions from non-insulin-stimulated fat cells was larger than in untrained rats. In both groups of rats, insulin stimulation of adipocytes decreased the number of glucose transporters in low-density microsomes by about 60% and increased the number of glucose transporters in the plasma membrane fractions. The number of glucose transporters in the plasma membrane fractions from maximally insulin-stimulated fat cells was larger in trained rats than in control rats. [U-¹⁴C]Glucose incorporation into lipids varied in proportion to plasma membrane cytochalasin B binding per cell under all conditions tested. The results explain the enhancing effect of training on insulin responsiveness transport of hexose in fat cells.     

Diversity of prolactin systems in the insect Leucophaea maderae: Use of antiserum polyclonality for immunocytochemical detection of neuropeptide heterogeneity

Summary The presence of prolactin-like neuropeptides was demonstrated immunocytochemically in the brain and affiliated neuroendocrine structures of the insect Leucophaea maderae. Use of the unlabelled peroxidase-antiperoxidase method of Sternberger revealed a rather widespread and differential distribution of reaction products resembling human (hPRL) and ovine (oPRL) prolactin. Tests with antirat PRL antibody were negative. The specificity of the antibodies used was established by liquid-phase absorptions and confirmed in tissue control systems. In L. maderae, anti-oPRL identifies part of an oPRL-like molecule different from human and rat PRL. Anti-hPRL reveals part of a human and ovine PRL-like molecule different from rat prolactin. These results indicate the occurrence, in the nervous tissue of one insect species, of at least two types of prolactin-like molecules.Supported in part by SNF grants 11-5082 and 11-6652 (G.N.H.) and NIH Grant NS 22344-02 (B.S.). The authors are indebted to Mrs. Bente Hershøj for skillful technical assistance     

The identity of Vincetoxicum in Norway

Norwegian Vincetoxicum has previously been referred to V. hirundinaria in standard floras but partly to an aberrant form, called var.fuscatum or ssp. fuscatum . Our comparative morphological and allozymatic data unambiguously relate present day Norwegian Vincetoxicum populations to V. rossicum as circumscribed in standard European floras, i. e. with brown corollas, dark purple coronas, and twining stems up to 2 m in height. However, specific status of this taxon is questionable and varietal rank has been suggested, e. g. V. hirundinaria var. rossicum . Present Norwegian occurrences probably represent descendants from introductions by man prior to 1865 (first Norwegian record). The species has established itself as a permanent member of the Norwegian flora and although restricted to relatively small areas in Oslo (Oslo Co.) and Drammen (Buskerud Co.), it shows invasive tendencies at present.     

SUMOylation of Pancreatic Glucokinase Regulates Its Cellular Stability and Activity

Glucokinase is the predominant hexokinase expressed in hepatocytes and pancreatic β-cells, with a pivotal role in regulating glucose-stimulated insulin secretion, illustrated by glucokinase gene mutations causing monogenic diabetes and congenital hyperinsulinemic hypoglycemia. A complex tissue-specific network of mechanisms regulates this enzyme, and a major unanswered question in glucokinase biology is how post-translational modifications control the function of the enzyme. Here, we show that the pancreatic isoform of human glucokinase is SUMOylated in vitro, using recombinant enzymes, and in insulin-secreting model cells. Three N-terminal lysines unique for the pancreatic isoform (Lys-12/Lys-13 and/or Lys-15) may represent one SUMOylation site, with an additional site (Lys-346) common for the pancreatic and the liver isoform. SUMO-1 and E2 overexpression stabilized preferentially the wild-type human pancreatic enzyme in MIN6 β-cells, and SUMOylation increased the catalytic activity of recombinant human glucokinase in vitro and also of glucokinase in target cells. Small ubiquitin-like modifier conjugation represents a novel form of post-translational modification of the enzyme, and it may have an important regulatory function in pancreatic β-cells.