Anti-diabetic properties of the Canadian lowbush blueberry Vaccinium angustifolium Ait.

Incidence of type II diabetes is rapidly increasing worldwide. In order to identify complementary or alternative approaches to existing medications, we studied anti-diabetic properties of Vaccinium angustifolium Ait., a natural health product recommended for diabetes treatment in Canada. Ethanol extracts of root, stem, leaf, and fruit were tested at 12.5 μg/ml for anti-diabetic activity in peripheral tissues and pancreatic β cells using a variety of cell-based bioassays. Specifically, we assessed: (1) deoxyglucose uptake in differentiated C2C12 muscle cells and 3T3-L1 adipocytes; (2) glucose-stimulated insulin secretion (GSIS) in β TC-tet pancreatic β cells; (3) β cell proliferation in β TC-tet cells; (4) lipid accumulation in differentiating 3T3-L1 cells; (5) protection against glucose toxicity in PC12 cells. Root, stem, and leaf extracts significantly enhanced glucose transport in C2C12 cells by 15–25% in presence and absence of insulin after 20 h of incubation; no enhancement resulted from a 1 h exposure. In 3T3 cells, only the root and stem extracts enhanced uptake, and this effect was greater after 1 h than after 20 h; uptake was increased by up to 75% in absence of insulin. GSIS was potentiated by a small amount in growth-arrested β TC-tet cells incubated overnight with leaf or stem extract. However, fruit extracts were found to increase ³H-thymidine incorporation in replicating β TC-tet cells by 2.8-fold. Lipid accumulation in differentiating 3T3-L1 cells was accelerated by root, stem, and leaf extracts by as much as 6.5-fold by the end of a 6-day period. Stem, leaf, and fruit extracts reduced apoptosis by 20–33% in PC12 cells exposed to elevated glucose for 96 h. These results demonstrate that V. angustifolium contains active principles with insulin-like and glitazone-like properties, while conferring protection against glucose toxicity. Enhancement of proliferation in β cells may represent another potential anti-diabetic property. Extracts of the Canadian blueberry thus show promise for use as a complementary anti-diabetic therapy.     

Structure–activity relationship (SAR) studies of 3-(2-amino-ethyl)-5-(4-ethoxy-benzylidene)-thiazolidine-2,4-dione: Development of potential substrate-specific ERK1/2 inhibitors

A series of analogs of 3-(2-amino-ethyl)-5-(4-ethoxy-benzylidene)-thiazolidine-2,4-dione, a putative substrate-specific ERK1/2 inhibitor, were synthesized and biologically characterized in human leukemia U937 cells to define its pharmacophore. It was discovered that shift of ethoxy substitution from the 4- to the 2-position on the phenyl ring significantly improved functional activities of inhibiting cell proliferation and inducing apoptosis. This may provide access to a new lead for developing ERK1/2 substrate-specific inhibitors.     

Metabolic engineering and characterization of phaC1 and phaC2 genes from Pseudomonas putida KCTC1639 for overproduction of medium-chain-length polyhydroxyalkanoate

Two PHA synthase phaC1 and phaC2 genes cloned from the new strain Pseudomonas putida KCTC1639 were metabolically engineered for the overproduction of medium-chain-length polyhydroxyalkanoate (mcl-PHA). The overexpressed phaC1 and phaC2 genes in P. putida KCTC1639 were compared in terms of the biosynthesis of mcl-PHA, fatty acid assimilation, distribution of 3-hydroxylacyl monomer units, granular morphology, and thermophysical properties of the accumulated mcl-PHA. The biosynthesis of mcl-PHA was enhanced only by the overexpressed phaC1 gene up to 2.86-fold, in contrast, the phaC2 gene did not activate the biosynthesis of mcl-PHA. The overexpressed phaC1 gene tended to form enlarged, high molecular weight, and lower crystalline mcl-PHA granules, whereas the amplified phaC2 gene induced the fragmentation of mcl-PHA into a few small-sized granules. The transformant P. putida KCTC1639 overexpressing the phaC1 gene encoding PHA synthase I was cultivated by pH-stat fed-batch cultivation, and the concentration and content of mcl-PHA increased up to 8.91 g L-1 and 70.5%, respectively.     

Serum Glucose and Fructosamine in Relation to Risk of Cancer

Background

Impaired glucose metabolism has been linked with increased cancer risk, but the association between serum glucose and cancer risk remains unclear. We used repeated measurements of glucose and fructosamine to get more insight into the association between the glucose metabolism and risk of cancer.

Methods

We selected 11,998 persons (>20 years old) with four prospectively collected serum glucose and fructosamine measurements from the Apolipoprotein Mortality Risk (AMORIS) study. Multivariate Cox proportional hazards regression was used to assess standardized log of overall mean glucose and fructosamine in relation to cancer risk. Similar analyses were performed for tertiles of glucose and fructosamine and for different types of cancer.

Results

A positive trend was observed between standardized log overall mean glucose and overall cancer risk (HR = 1.08; 95% CI: 1.02–1.14). Including standardized log fructosamine in the model resulted in a stronger association between glucose and cancer risk and aninverse association between fructosamine and cancer risk (HR = 1.17; 95% CI: 1.08–1.26 and HR: 0.89; 95% CI: 0.82–0.96, respectively). Cancer risks were highest among those in the highest tertile of glucose and lowest tertile of fructosamine. Similar findings were observed for prostate, lung, and colorectal cancer while none observed for breast cancer.

Conclusion

The contrasting effect between glucose, fructosamine, and cancer risk suggests the existence of distinct groups among those with impaired glucose metabolism, resulting in different cancer risks based on individual metabolic profiles. Further studies are needed to clarify whether glucose is a proxy of other lifestyle-related or metabolic factors.     

Functional interaction of heterogeneous nuclear ribonucleoprotein C with poliovirus RNA synthesis initiation complexes

We had previously demonstrated that a cellular protein specifically interacts with the 3' end of poliovirus negative-strand RNA. We now report the identity of this protein as heterogeneous nuclear ribonucleoprotein (hnRNP) C1/C2. Formation of an RNP complex with poliovirus RNA was severely impaired by substitution of a lysine, highly conserved among vertebrates, with glutamine in the RNA recognition motif (RRM) of recombinant hnRNP C1, suggesting that the binding is mediated by the RRM in the protein. We have also shown that in a glutathione S-transferase (GST) pull-down assay, GST/hnRNP C1 binds to poliovirus polypeptide 3CD, a precursor to the viral RNA-dependent RNA polymerase, 3D(pol), as well as to P2 and P3, precursors to the nonstructural proteins. Truncation of the auxiliary domain in hnRNP C1 (C1DeltaC) diminished these protein-protein interactions. When GST/hnRNP C1DeltaC was added to in vitro replication reactions, a significant reduction in RNA synthesis was observed in contrast to reactions supplemented with wild-type fusion protein. Indirect functional depletion of hnRNP C from in vitro replication reactions, using poliovirus negative-strand cloverleaf RNA, led to a decrease in RNA synthesis. The addition of GST/hnRNP C1 to the reactions rescued RNA synthesis to near mock-depleted levels. Furthermore, we demonstrated that poliovirus positive-strand and negative-strand RNA present in cytoplasmic extracts prepared from infected HeLa cells coimmunoprecipitated with hnRNP C1/C2. Our findings suggest that hnRNP C1 has a role in positive-strand RNA synthesis in poliovirus-infected cells, possibly at the level of initiation.     

Augmentation of T cell levels and responses induced by androgen deprivation

Androgen has been implicated as a negative regulator of host immune function and a factor contributing to the gender dimorphism of autoimmunity. Conversely, androgen deprivation has been suggested to potentiate male host immunity. Studies have shown that removal of androgen in postpubertal male mice produces an increase in size and cellularity of primary and peripheral lymphoid organs, and enhances a variety of immune responses. Yet, few details are known about the effect of androgen removal on T cell-mediated immunity. In this study, we demonstrate two pronounced and independent alterations in T cell immunity that occur in response to androgen deprivation, provided by castration, in postpubertal male mice. First, we show that levels of T cells in peripheral lymphoid tissues of mice are increased by androgen deprivation. Second, T cells from these mice transiently proliferate more vigorously to TCR- and CD28-mediated costimulation as well as to Ag-specific activation. In addition, androgen deprivation accelerates normalization of host T and B cell levels following chemotherapy-induced lymphocyte depletion. Such alterations induced by androgen deprivation may have implications for enhancing immune responses to immunotherapy and for accelerating the recovery of the immune system following chemotherapy.     

Altered migration, recruitment, and somatic hypermutation in the early response of marginal zone B cells to T cell-dependent antigen

The early responses of follicular (Fo) and marginal zone (MZ) B cells to T cell-dependent Ag were compared using anti-hen egg lysozyme (HEL+) B cells capable of class switch recombination and somatic hypermutation (SHM). Purified CD21/(35int)CD23high Fo and CD21/35(high)CD23low MZ splenic B cells from SW(HEL) Ig-transgenic mice were transferred into wild-type recipients and challenged with HEL-sheep RBC. Responding HEL+ B cells from both populations switched efficiently to IgG1, generated syndecan-1+ Ab-secreting cells, and exhibited equivalent rates of proliferation. However, the expansion of HEL+ MZ B cells lagged significantly behind that of HEL+ Fo B cells due to less efficient homing to the outer periarteriolar lymphatic sheath and reduced recruitment into the proliferative response. Despite the equivalent rates of class switch recombination, the onset of SHM was delayed in the MZ subset, indicating that these two activation-induced cytidine deaminase-dependent events are uncoupled in the early response of MZ B cells. Migration of HEL+ B cells into germinal centers coincided with the onset of SHM, occurring more rapidly with Fo vs MZ responders. These results are consistent with the concept that Fo and MZ B cells have evolved to specialize in T cell-dependent and T-independent responses respectively.     

Unique Dental Morphology of Homo floresiensis and Its Evolutionary Implications

Homo floresiensis is an extinct, diminutive hominin species discovered in the Late Pleistocene deposits of Liang Bua cave, Flores, eastern Indonesia. The nature and evolutionary origins of H. floresiensis’ unique physical characters have been intensively debated. Based on extensive comparisons using linear metric analyses, crown contour analyses, and other trait-by-trait morphological comparisons, we report here that the dental remains from multiple individuals indicate that H. floresiensis had primitive canine-premolar and advanced molar morphologies, a combination of dental traits unknown in any other hominin species. The primitive aspects are comparable to H. erectus from the Early Pleistocene, whereas some of the molar morphologies are more progressive even compared to those of modern humans. This evidence contradicts the earlier claim of an entirely modern human-like dental morphology of H. floresiensis, while at the same time does not support the hypothesis that H. floresiensis originated from a much older H. habilis or Australopithecus-like small-brained hominin species currently unknown in the Asian fossil record. These results are however consistent with the alternative hypothesis that H. floresiensis derived from an earlier Asian Homo erectus population and experienced substantial body and brain size dwarfism in an isolated insular setting. The dentition of H. floresiensis is not a simple, scaled-down version of earlier hominins.