Effects of diet and exercise in preventing NIDDM in people with impaired glucose tolerance. The Da Qing IGT and Diabetes Study

OBJECTIVE

Individuals with impaired glucose tolerance (IGT) have a high risk of developing NIDDM. The purpose of this study was to determine whether diet and exercise interventions in those with IGT may delay the development of NIDDM, i.e., reduce the incidence of NIDDM, and thereby reduce the overall incidence of diabetic complications, such as cardiovascular, renal, and retinal disease, and the excess mortality attributable to these complications.

RESEARCH DESIGN AND METHODS

In 1986, 110,660 men and women from 33 health care clinics in the city of Da Qing, China, were screened for IGT and NIDDM. Of these individuals, 577 were classified (using World Health Organization criteria) as having IGT. Subjects were randomized by clinic into a clinical trial, either to a control group or to one of three active treatment groups: diet only, exercise only, or diet plus exercise. Follow-up evaluation examinations were conducted at 2-year intervals over a 6-year period to identify subjects who developed NIDDM. Cox's proportional hazard analysis was used to determine if the incidence of NIDDM varied by treatment assignment.

RESULTS

The cumulative incidence of diabetes at 6 years was 67.7% (95% CI, 59.8-75.2) in the control group compared with 43.8% (95% CI, 35.5-52.3) in the diet group, 41.1% (95% CI, 33.4-49.4) in the exercise group, and 46.0% (95% CI, 37.3-54.7) in the diet-plus-exercise group (P < 0.05). When analyzed by clinic, each of the active intervention groups differed significantly from the control clinics (P < 0.05). The relative decrease in rate of development of diabetes in the active treatment groups was similar when subjects were stratified as lean or overweight (BMI < or > or = 25 kg/m2). In a proportional hazards analysis adjusted for differences in baseline BMI and fasting glucose, the diet, exercise, and diet-plus-exercise interventions were associated with 31% (P < 0.03), 46% (P < 0.0005), and 42% (P < 0.005) reductions in risk of developing diabetes, respectively.

CONCLUSIONS

Diet and/or exercise interventions led to a significant decrease in the incidence of diabetes over a 6-year period among those with IGT.

Treatment with a copper-zinc chelator markedly and rapidly inhibits beta-amyloid accumulation in Alzheimer's disease transgenic mice

Inhibition of neocortical beta-amyloid (Abeta) accumulation may be essential in an effective therapeutic intervention for Alzheimer's disease (AD). Cu and Zn are enriched in Abeta deposits in AD, which are solubilized by Cu/Zn-selective chelators in vitro. Here we report a 49% decrease in brain Abeta deposition (-375 microg/g wet weight, p = 0.0001) in a blinded study of APP2576 transgenic mice treated orally for 9 weeks with clioquinol, an antibiotic and bioavailable Cu/Zn chelator. This was accompanied by a modest increase in soluble Abeta (1.45% of total cerebral Abeta); APP, synaptophysin, and GFAP levels were unaffected. General health and body weight parameters were significantly more stable in the treated animals. These results support targeting the interactions of Cu and Zn with Abeta as a novel therapy for the prevention and treatment of AD.

Epitaxial BiFeO3 multiferroic thin film heterostructures

Enhancement of polarization and related properties in heteroepitaxially constrained thin films of the ferroelectromagnet, BiFeO3, is reported. Structure analysis indicates that the crystal structure of film is monoclinic in contrast to bulk, which is rhombohedral. The films display a room-temperature spontaneous polarization (50 to 60 microcoulombs per square centimeter) almost an order of magnitude higher than that of the bulk (6.1 microcoulombs per square centimeter). The observed enhancement is corroborated by first-principles calculations and found to originate from a high sensitivity of the polarization to small changes in lattice parameters. The films also exhibit enhanced thickness-dependent magnetism compared with the bulk. These enhanced and combined functional responses in thin film form present an opportunity to create and implement thin film devices that actively couple the magnetic and ferroelectric order parameters.

Congenital deafness and sinoatrial node dysfunction in mice lacking class D L-type Ca2+ channels

Voltage-gated L-type Ca2+ channels (LTCCs) containing a pore-forming alpha1D subunit (D-LTCCs) are expressed in neurons and neuroendocrine cells. Their relative contribution to total L-type Ca2+ currents and their physiological role and significance as a drug target remain unknown. Therefore, we generated D-LTCC deficient mice (alpha1D-/-) that were viable with no major disturbances of glucose metabolism. alpha1D-/-mice were deaf due to the complete absence of L-type currents in cochlear inner hair cells and degeneration of outer and inner hair cells. In wild-type controls, D-LTCC-mediated currents showed low activation thresholds and slow inactivation kinetics. Electrocardiogram recordings revealed sinoatrial node dysfunction (bradycardia and arrhythmia) in alpha1D-/- mice. We conclude that alpha1D can form LTCCs with negative activation thresholds essential for normal auditory function and control of cardiac pacemaker activity.

Involvement of caspases in proteolytic cleavage of Alzheimer's amyloid-beta precursor protein and amyloidogenic A beta peptide formation

The amyloid-beta precursor protein (APP) is directly and efficiently cleaved by caspases during apoptosis, resulting in elevated amyloid-beta (A beta) peptide formation. The predominant site of caspase-mediated proteolysis is within the cytoplasmic tail of APP, and cleavage at this site occurs in hippocampal neurons in vivo following acute excitotoxic or ischemic brain injury. Caspase-3 is the predominant caspase involved in APP cleavage, consistent with its marked elevation in dying neurons of Alzheimer's disease brains and colocalization of its APP cleavage product with A beta in senile plaques. Caspases thus appear to play a dual role in proteolytic processing of APP and the resulting propensity for A beta peptide formation, as well as in the ultimate apoptotic death of neurons in Alzheimer's disease.

Presenilin 1 is required for Notch1 and DII1 expression in the paraxial mesoderm

Approximately 10% of cases of Alzheimer's disease are familial and associated with autosomal dominant inheritance of mutations in genes encoding the amyloid precursor protein, presenilin 1 (PS1) and presenilin 2 (PS2). Mutations in PS1 are linked to about 25% of cases of early-onset familial Alzheimer's disease. PS1, which is endoproteolytically processed in vivo, is a multipass transmembrane protein and is a functional homologue of SEL-12, a Caenorhabditis elegans protein that facilitates signalling mediated by the Notch/LIN-12 family of receptors. To examine potential roles for PS1 in facilitating Notch-mediated signalling during mammalian embryogenesis, we generated mice with targeted disruptions of PS1 alleles (PS1-/- mice). PS1-/- embryos exhibited abnormal patterning of the axial skeleton and spinal ganglia, phenotypes traced to defects in somite segmentation and differentiation. Moreover, expression of mRNA encoding Notch1 and Dll1 (delta-like gene 1), a vertebrate Notch ligand, is markedly reduced in the presomitic mesoderm of PS1-/- embryos compared to controls. Hence, PS1 is required for the spatiotemporal expression of Notch1 and Dll1, which are essential for somite segmentation and maintenance of somite borders.

beta-Amyloid precursor protein-deficient mice show reactive gliosis and decreased locomotor activity

In several pedigrees of early onset familial Alzheimer's disease (FAD), point mutations in the beta-amyloid precursor protein (APP) gene are genetically linked to the disease. This finding implicates APP in the pathogenesis of Alzheimer's disease in these individuals. To understand the in vivo function of APP and its processing, we have generated an APP-null mutation in mice. Homozygous APP-deficient mice were viable and fertile. However, the mutant animals weighed 15%-20% less than age-matched wild-type controls. Neurological evaluation showed that the APP-deficient mice exhibited a decreased locomotor activity and forelimb grip strength, indicating a compromised neuronal or muscular function. In addition, four out of six homozygous mice showed reactive gliosis at 14 weeks of age, suggesting an impaired neuronal function as a result of the APP-null mutation.

Influenza A virus NS1 protein prevents activation of NF-kappaB and induction of alpha/beta interferon

The alpha/beta interferon (IFN-alpha/beta) system represents one of the first lines of defense against virus infections. As a result, most viruses encode IFN antagonistic factors which enhance viral replication in their hosts. We have previously shown that a recombinant influenza A virus lacking the NS1 gene (delNS1) only replicates efficiently in IFN-alpha/beta-deficient systems. Consistent with this observation, we found that infection of tissue culture cells with delNS1 virus, but not with wild-type influenza A virus, induced high levels of mRNA synthesis from IFN-alpha/beta genes, including IFN-beta. It is known that transactivation of the IFN-beta promoter depends on NF-kappaB and several other transcription factors. Interestingly, cells infected with delNS1 virus showed high levels of NF-kappaB activation compared with those infected with wild-type virus. Expression of dominant-negative inhibitors of the NF-kappaB pathway during delNS1 virus infection prevented the transactivation of the IFN-beta promoter, demonstrating a functional link between NF-kappaB activation and IFN-alpha/beta synthesis in delNS1 virus-infected cells. Moreover, expression of the NS1 protein prevented virus- and/or double-stranded RNA (dsRNA)-mediated activation of the NF-kappaB pathway and of IFN-beta synthesis. This inhibitory property of the NS1 protein of influenza A virus was dependent on its ability to bind dsRNA, supporting a model in which binding of NS1 to dsRNA generated during influenza virus infection prevents the activation of the IFN system. NS1-mediated inhibition of the NF-kappaB pathway may thus play a key role in the pathogenesis of influenza A virus.

Multiferroic BaTiO3-CoFe2O4 Nanostructures

We report on the coupling between ferroelectric and magnetic order parameters in a nanostructured BaTiO3-CoFe2O4 ferroelectromagnet. This facilitates the interconversion of energies stored in electric and magnetic fields and plays an important role in many devices, including transducers, field sensors, etc. Such nanostructures were deposited on single-crystal SrTiO3 (001) substrates by pulsed laser deposition from a single Ba-Ti-Co-Fe-oxide target. The films are epitaxial in-plane as well as out-of-plane with self-assembled hexagonal arrays of CoFe2O4 nanopillars embedded in a BaTiO3 matrix. The CoFe2O4 nanopillars have uniform size and average spacing of 20 to 30 nanometers. Temperature-dependent magnetic measurements illustrate the coupling between the two order parameters, which is manifested as a change in magnetization at the ferroelectric Curie temperature. Thermodynamic analyses show that the magnetoelectric coupling in such a nanostructure can be understood on the basis of the strong elastic interactions between the two phases.

UNC-40, a C. elegans homolog of DCC (Deleted in Colorectal Cancer), is required in motile cells responding to UNC-6 netrin cues

UNC-6 netrin, a laminin-related protein secreted from neuroglia and neurons along the ventral midline, orients migrating cells and pioneering growth cones on the nematode epidermis. UNC-5, a cell surface protein expressed on motile cells and pioneer axons, orients movements away from UNC-6 sources. UNC-40, a homolog of the cell surface proteins DCC (Deleted in Colorectal Cancer) and neogenin, is also expressed on motile cells and pioneer neurons. UNC-40 acts cell autonomously to orient movement toward UNC-6 sources. For cells coexpressing UNC-5, it helps orient movement away from UNC-6 sources. Finally, UNC-40 helps determine the dorsoventral position of cells undergoing purely longitudinal migrations. Together with the recent report that DCC is a netrin receptor in vertebrates, our results suggest that UNC-40 is a component of UNC-6 receptors on motile cells.

Mice lacking both presenilin genes exhibit early embryonic patterning defects

Genetic studies in worms, flies, and humans have implicated the presenilins in the regulation of the Notch signaling pathway and in the pathogenesis of Alzheimer's Disease. There are two highly homologous presenilin genes in mammals, presenilin 1 (PS1) and presenilin 2 (PS2). In mice, inactivation of PS1 leads to developmental defects that culminate in a perinatal lethality. To test the possibility that the late lethality of PS1-null mice reflects genetic redundancy of the presenilins, we have generated PS2-null mice by gene targeting, and subsequently, PS1/PS2 double-null mice. Mice homozygous for a targeted null mutation in PS2 exhibit no obvious defects; however, loss of PS2 on a PS1-null background leads to embryonic lethality at embryonic day 9.5. Embryos lacking both presenilins, and surprisingly, those carrying only a single copy of PS2 on a PS1-null background, exhibit multiple early patterning defects, including lack of somite segmentation, disorganization of the trunk ventral neural tube, midbrain mesenchyme cell loss, anterior neuropore closure delays, and abnormal heart and second branchial arch development. In addition, Delta like-1 (Dll1) and Hes-5, two genes that lie downstream in the Notch pathway, were misexpressed in presenilin double-null embryos: Hes-5 expression was undetectable in these mice, whereas Dll1 was expressed ectopically in the neural tube and brain of double-null embryos. We conclude that the presenilins play a widespread role in embryogenesis, that there is a functional redundancy between PS1 and PS2, and that both vertebrate presenilins, like their invertebrate homologs, are essential for Notch signaling.

Kruppel-like factor 4 (KLF4) is required for maintenance of breast cancer stem cells and for cell migration and invasion

Kruppel-like factor 4 (KLF4) is highly expressed in more than 70% of breast cancers and functions as an oncogene. However, an exact mechanism by which KLF4 enhances tumorigenesis of breast cancer remains unknown. In this study, we show that KLF4 was highly expressed in cancer stem cell (CSC)-enriched populations in mouse primary mammary tumor and breast cancer cell lines. Knockdown of KLF4 in breast cancer cells (MCF-7 and MDA-MB-231) decreased the proportion of stem/progenitor cells as demonstrated by expression of stem cell surface markers such as aldehyde dehydrogenase 1 (ALDH1), side-population (SP), and by in vitro mammosphere assay. Consistently KLF4 overexpression led to an increase of the cancer stem cell population. KLF4 knockdown also suppressed cell migration and invasion in MCF-7 and MDA-MB-231 cells. Furthermore, knockdown of KLF4 reduced colony formation in vitro and inhibited tumorigenesis in immunocompromised NOD/SCID mice, supporting an oncogenic role for KLF4 in breast cancer development. Further mechanistic studies revealed that the Notch signaling pathway was required for KLF4-mediated cell migration and invasion, but not for CSC maintenance. Taken together, our study provides evidence that KLF4 plays a potent oncogenic role in mammary tumorigenesis likely by maintaining stem cell-like features and by promoting cell migration and invasion. Thus, targeting KLF4 may provide an effective therapeutic approach to suppress tumorigenicity in breast cancer.

CX3C chemokine mimicry by respiratory syncytial virus G glycoprotein

Chemokines are chemoattractant proteins that are divided into subfamilies based upon cysteine signature motifs termed C, CC, CXC and CX3C. Chemokines have roles in immunity and inflammation that affect cell trafficking and activation of T cells as well as cells of the innate immune system. We report here CX3C chemokine mimicry for the G glycoprotein of respiratory syncytial virus (RSV) and show binding to CX3CR1--the specific receptor for the CX3C chemokine fractalkine--and induction of leukocyte chemotaxis. We also show that CX3CR1 facilitates RSV infection of cells. Thus, G glycoprotein interaction with CX3CR1 probably plays a key role in the biology of RSV infection.

Resistance to fever induction and impaired acute-phase response in interleukin-1 beta-deficient mice

We used gene targeting in embryonic stem cells to introduce an IL-1 beta null allele in mice. The IL-1 beta-deficient mice develop normally and are apparently healthy and fertile. The IL-1 beta null mice responded normally in models of contact and delayed-type hypersensitivity or following bacterial endotoxin LPS-induced inflammation. The IL-1 beta-deficient mice showed equivalent resistance to Listeria monocytogenes compared with wild-type controls. In contrast, when challenged with turpentine, which causes localized inflammation and tissue injury, the IL-1 beta mutant mice exhibited an impaired acute-phase inflammatory response and were completely resistant to fever development and anorexia. These results highlight a central role for IL-1 beta as a pyrogen and a mediator of the acute-phase response in a subset of inflammatory disease models, and support the notion that blocking the action of a single key cytokine can alter the course of specific immune and inflammatory responses.

Neuronal repair. Asynchronous therapy restores motor control by rewiring of the rat corticospinal tract after stroke

The brain exhibits limited capacity for spontaneous restoration of lost motor functions after stroke. Rehabilitation is the prevailing clinical approach to augment functional recovery, but the scientific basis is poorly understood. Here, we show nearly full recovery of skilled forelimb functions in rats with large strokes when a growth-promoting immunotherapy against a neurite growth-inhibitory protein was applied to boost the sprouting of new fibers, before stabilizing the newly formed circuits by intensive training. In contrast, early high-intensity training during the growth phase destroyed the effect and led to aberrant fiber patterns. Pharmacogenetic experiments identified a subset of corticospinal fibers originating in the intact half of the forebrain, side-switching in the spinal cord to newly innervate the impaired limb and restore skilled motor function.

UNC-73 activates the Rac GTPase and is required for cell and growth cone migrations in C. elegans

unc-73 is required for cell migrations and axon guidance in C. elegans and encodes overlapping isoforms of 283 and 189 kDa that are closely related to the vertebrate Trio and Kalirin proteins, respectively. UNC-73A contains, in order, eight spectrin-like repeats, a Dbl/Pleckstrin homology (DH/PH) element, an SH3-like domain, a second DH/PH element, an immunoglobulin domain, and a fibronectin type III domain. UNC-73B terminates just downstream of the SH3-like domain. The first DH/PH element specifically activates the Rac GTPase in vitro and stimulates actin polymerization when expressed in Rat2 cells. Both functions are eliminated by introducing the S1216F mutation of unc-73(rh40) into this DH domain. Our results suggest that UNC-73 acts cell autonomously in a protein complex to regulate actin dynamics during cell and growth cone migrations.

Multilayer control of the EMT master regulators

Metastasis is the leading cause of cancer-associated death in most tumor types. Metastatic dissemination of cancer cells from the primary tumor is believed to be initiated by the reactivation of an embryonic development program referred to as epithelial-mesenchymal transition (EMT), whereby epithelial cells lose apicobasal polarity and cell-cell contacts, and gain mesenchymal phenotypes with increased migratory and invasive capabilities. EMT has also been implicated in the regulation of cancer stem cell property, immune suppression and cancer regression. Several transcription factors have been identified as master regulators of EMT, including the Snail, Zeb and Twist families, and their expression is tightly regulated at different steps of transcription, translation and protein stability control by a variety of cell-intrinsic pathways as well as extracellular cues. Here, we review the recent literature on the signaling pathways and mechanisms that control the expression of these master transcription factors during EMT and cancer progression.

Age-related cognitive deficits, impaired long-term potentiation and reduction in synaptic marker density in mice lacking the beta-amyloid precursor protein

Mutations in the beta-amyloid precursor protein are strongly associated with some cases of familial Alzheimer's disease. The normal physiological role of beta-amyloid precursor protein in the brain was evaluated in a cross-sectional analysis of mice deficient in beta-amyloid precursor protein. Compared with wild-type control mice the beta-amyloid precursor protein-null mice developed age-dependent deficits in cognitive function and also had impairments in long-term potentiation. In addition, the brains of the beta-amyloid precursor protein-null mice had marked reactive gliosis in many areas, especially in the cortex and hippocampus. A subpopulation of mice (n = 15) died prematurely (between three and 18 months of age). Analysis of another six mice from the same population that were showing weight loss and hypolocomotor activity exhibited a marked reactive gliosis as detected by immunoreactivity for glial fibrillary acidic protein and a profound loss of immunoreactivities for the presynaptic terminal vesicle marker proteins synaptophysin and synapsin and the dendritic marker microtubule-associated protein-2 in many brain areas, but most predominantly in the cortex and hippocampus. These results suggest that normal beta-amyloid precursor protein may serve an essential role in the maintenance of synaptic function during ageing. A compromise of this function of the beta-amyloid precursor protein may contribute to the progression of the memory decline and the neurodegenerative changes seen in Alzheimer's disease.

Influenza A and B viruses expressing altered NS1 proteins: A vaccine approach

We propose a rational approach to the generation of live viral vaccines: alteration of virally encoded type I IFN antagonists to attenuate virulence while retaining immunogenicity. We have explored this concept by using the influenza virus. Previously we have shown that the NS1 protein of influenza A virus possesses anti-IFN activity. We now present evidence that influenza A and B viruses encoding altered viral NS1 proteins are highly attenuated in the mouse host, yet provide protection from challenge with wild-type viruses.

Hoxb-4 (Hox-2.6) mutant mice show homeotic transformation of a cervical vertebra and defects in the closure of the sternal rudiments

Two Hoxb-4 (Hox-2.6) mutations were introduced into the mouse germline. The overt phenotype caused by one of the mutations was assayed on two different genetic backgrounds, an inbred 129SvEv and a hybrid 129SvEv-C57BL/6J. The allele hoxb-4' is a disruption of the first exon and causes two obvious skeletal changes: a partial homeotic transformation of the second cervical vertebra from axis to atlas and a defective morphogenesis of the sternum. Both phenotypes have incomplete penetrance and variable expressivity when assayed in the hybrid genetic background, but the sternum defect is completely penetrant in the inbred background. The mutant allele hoxb-4s has a premature stop codon, introduced by the "hit and run" method in the second exon, that disrupts the third helix of the homeodomain. This allele also causes the partial homeotic transformation of axis to atlas, but it does not affect the sternum.