Cerebral and cerebellar gray matter reduction in first-episode patients with major depressive disorder: a voxel-based morphometry study

PURPOSE

To investigate cerebral and cerebellar gray matter abnormalities in patients with first-episode major depressive disorder (MDD).

MATERIALS AND METHODS

We examined the structural difference in regional gray matter density (GMD) between 22 first-episode MDD patients and 30 age-, gender- and education-matched healthy controls by optimized voxel-based morphometry (VBM) based on magnetic resonance imaging.

RESULTS

Compared with healthy controls, MDD patients showed decreased GMD in the right medial and left lateral orbitofrontal cortex, right dorsolateral prefrontal cortex (DLPFC), bilateral temporal pole, right superior temporal gyrus, bilateral anterior insular cortex, left parahippocampal gyrus, and left cerebellum. In addition, in MDD patients, there was a negative correlation between GMD values of the right DLPFC and the score of the depression rating scale.

CONCLUSIONS

Our findings provided additional support for the involvement of limbic-cortical circuits in the pathophysiology of MDD and preliminary evidence that a defect involving the cerebellum may also be implicated.

White-matter volume reduction and the protective effect of immunosuppressive therapy in systemic lupus erythematosus patients with normal appearance by conventional magnetic resonance imaging

OBJECTIVE

The central nervous system (CNS) is often affected by systemic lupus erythematosus (SLE), but assessment of CNS outcomes using noninvasive cerebral structural measures remains in its infancy. Magnetic resonance imaging (MRI) with expert visual interpretation is critical to diagnosis, but does not permit quantitative measurements. Our pilot study investigated whether quantitative brain volumetric analyses could be used to detect white-matter (WM) abnormalities and responses to treatment in SLE (ClinicalTrials.gov: NCT00703742).

METHODS

Forty-two pairs of SLE patients and healthy controls underwent high-resolution 3-dimensional structural MRI scans. Combining voxel-based morphometry and region of interest analyses, subtle WM volume abnormalities in whole brains from SLE patients were identified, and regional WM volume was calculated. Associations between WM volume and symptom severity, as well as the effects of immunosuppressive therapy, were then investigated.

RESULTS

The WM volume of the SLE group was significantly decreased in the bilateral posterior and anterior crus of the internal capsule (PIC and AIC, respectively), the subgyral right frontal lobe, and left temporal lobe (p < 0.001). Regional WM volume (left PIC and right AIC) was correlated with SLEDAI scores. The WM volume of patients treated with immunosuppressive therapy was greater than that of patients who were never treated with immunosuppressive therapy.

CONCLUSION

Quantitative brain volumetric analyses detect brain injuries in WM for SLE that are not obvious by conventional MRI, and may be adequately sensitive and quantitative to measure the effect of therapeutic interventions in preventing brain injury and outcomes in SLE.

Curcumin acts as anti-tumorigenic and hormone-suppressive agent in murine and human pituitary tumour cells in vitro and in vivo

Curcumin (diferuloylmethane) is the active ingredient of the spice plant Curcuma longa and has been shown to act anti-tumorigenic in different types of tumours. Therefore, we have studied its effect in pituitary tumour cell lines and adenomas. Proliferation of lactosomatotroph GH3 and somatotroph MtT/S rat pituitary cells as well as of corticotroph AtT20 mouse pituitary cells was inhibited by curcumin in monolayer cell culture and in colony formation assay in soft agar. Fluorescence-activated cell sorting (FACS) analysis demonstrated curcumin-induced cell cycle arrest at G2/M. Analysis of cell cycle proteins by immunoblotting showed reduction in cyclin D(1), cyclin-dependent kinase 4 and no change in p27(kip). FACS analysis with Annexin V-FITC/7-aminoactinomycin D staining demonstrated curcumin-induced early apoptosis after 3, 6, 12 and 24 h treatment and nearly no necrosis. Induction of DNA fragmentation, reduction of Bcl-2 and enhancement of cleaved caspase-3 further confirmed induction of apoptosis by curcumin. Growth of GH3 tumours in athymic nude mice was suppressed by curcumin in vivo. In endocrine pituitary tumour cell lines, GH, ACTH and prolactin production were inhibited by curcumin. Studies in 25 human pituitary adenoma cell cultures have confirmed the anti-tumorigenic and hormone-suppressive effects of curcumin. Altogether, the results described in this report suggest this natural compound as a good candidate for therapeutic use on pituitary tumours.

Schizophrenia patients and their healthy siblings share disruption of white matter integrity in the left prefrontal cortex and the hippocampus but not the anterior cingulate cortex

Healthy siblings of schizophrenia patients have an almost 9-fold higher risk for developing the illness than the general population. Disruption of white matter (WM) integrity as indicated by reduced fractional anisotropy (FA) derived from diffusion tensor imaging (DTI), is believed to be the key substrate of schizophrenia. However, it remains unclear whether schizophrenia patients and their healthy siblings share a specific pattern of disruption of WM integrity that may be related to the disease risk. The objective of this study is to determine whether a specific brain regional pattern of disruption of WM integrity is shared by schizophrenia patients and their healthy siblings. We investigated brain white matter abnormalities by voxel-based analysis of white matter FA data acquired from diffusion tensor imaging in 34 pairs of schizophrenia patients and their healthy siblings, as well as in 32 healthy controls. Both schizophrenia patients and their healthy siblings showed reduced white matter FA in the left prefrontal cortex and the hippocampus in comparison to healthy controls, without significant difference between patients and siblings. In marked contrast, only schizophrenia patients exhibited reduced white matter FA in the left anterior cingulate cortex in comparison to both siblings and controls, without significant difference between siblings and controls. Thus, schizophrenia patients and their healthy siblings share disruption of WM integrity in the left prefrontal cortex and the hippocampus that may be related to higher risk of healthy siblings to develop schizophrenia, which may be eventually attributed to additional disruption of WM integrity in the left anterior cingulate cortex.

Meat quality is associated with muscle metabolic status but not contractile myofiber type composition in premature pigs

Longissimus muscles were sampled from Erhualian (EHL) and Pietrain (PIE) pigs at 20kg of body weight. No breed differences were detected in either the proportions or the mRNA/protein expression of respective MyHC isoforms, or the mRNA expression of PGC-1α (all P>0.10). However, meat quality traits were already divergent between breeds, and were associated with distinct energy metabolic status, as reflected by dramatically lower AMPK activity yet higher CK and LDH activities (all P<0.01) in longissimus muscle of EHL pigs. Moreover, mRNA expression of glucocorticoid receptor (GR) was found to be higher (P<0.05) in longissimus muscle of EHL pigs. These results indicate that the differences in meat quality traits occur early in premature pigs, and these are attributed to skeletal muscle energy metabolism and not contractile myofiber type composition. Breed-specific GR expression in muscle may be related to the pattern of energy metabolism and meat quality, yet the mechanism awaits further investigation.

IL-27-mediated activation of natural killer cells and inflammation produced antitumour effects for human oesophageal carcinoma cells

Interleukin IL-27, composed of p28 and EBV-induced gene 3 subunits, has diverse functions in enhancing cell-mediated immunity and silencing the immunity. We examined whether forced expression of the p28-linked EBI3 gene in human oesophageal carcinoma cells (Eca109) produced antitumour effects in a T cell-defective condition. Tumour growth of Eca109 cells expressing IL-27 (Eca109/IL-27) was retarded in nude mice compared with parental and vector DNA-transduced tumours and survival of the mice inoculated with Eca109/IL-27 cells was prolonged. Expression of the tumour necrosis factor-alpha, IL-1beta and IL-6 genes was up-regulated in Eca109/IL-27 tumour specimens while the tumours remained small in size but the increased transcription was subsequently down-regulated in enlarged tumours. Spleen cells from mice-bearing Eca109/IL-27 tumours produced interferon-gamma and showed YAC-1-targeted cytotoxic activities greater than those of mice inoculated with parental or vector DNA-transducer tumours. Numbers of DX5+CD69+ natural killer cells in spleen of mice-bearing Eca109/IL-27 tumours and those of CD31+ cells within Eca109/IL-27 tumours remained the same as found in mice-bearing parental or vector DNA-transduced tumours. These data collectively suggest that the IL-27-mediated antitumour effects produced in a mature T cell-defective condition were attributable to enhanced interferon-gamma production and natural killer activities.

Whole-brain voxel-based morphometry of white matter in medial temporal lobe epilepsy

PURPOSE

The purpose of this study was to analyze whole-brain white matter changes in medial temporal lobe epilepsy (MTLE).

MATERIALS AND METHODS

We studied 23 patients with MTLE and 13 age- and sex-matched healthy control subjects using voxel-based morphometry (VBM) on T1-weighted 3D datasets. The seizure focus was right sided in 11 patients and left sided in 12. The data were collected on a 1.5 T MR system and analyzed by SPM 99 to generate white matter density maps.

RESULTS

Voxel-based morphometry revealed diffusively reduced white matter in MTLE prominently including bilateral frontal lobes, bilateral temporal lobes and corpus callosum. White matter reduction was also found in the bilateral cerebellar hemispheres in the left MTLE group.

CONCLUSION

VBM is a simple and automated approach that is able to identify diffuse whole-brain white matter reduction in MTLE.

Sensitive detection of PrPSc by Western blot assay based on streptomycin sulphate precipitation

Transmissible spongiform encephalopathies, also termed prion diseases, are fatal neurodegenerative disorders that affect both humans and animals, which are characterized by presences of protease-resistance disease-associated prion protein (PrP(Sc)) in brains. In the present study, we optimized the Western blot assay for PrP(Sc) with a precipitation procedure of streptomycin sulphate. After incubated with suitable amount of streptomycin sulphate, the detective sensitivity for PrP(Sc) was remarkably improved. The precipitation of PrP(Sc) was obviously influenced by pH value in the solution. Employs of PrP(Sc) stock sample into various mimic specimens, including normal hamster brain homogenate, human cerebrospinal fluid and urine, demonstrated that streptomycin precipitation markedly increased the detective sensitivity of PrP(Sc), regardless in low concentration or in large volume. In addition, the PrP(Sc) from a human brain tissue of familiar Creutzfeldt-Jakob disease (fCJD) was efficiently precipitated with streptomycin sulphate. As a sensitive, specific, rapid and flexible protocol for PrP(Sc), the protocol in this study has the potential, alone or combined with other techniques, to detect low levels of PrP(Sc) in the specimens not only from central nerve system, but also from peripheral organs or fluids.

Changes in FMRI in the human brain related to different durations of manual acupuncture needling

OBJECTIVES

The present study is aimed at evaluating the effects of manual acupuncture with different durations on the human brain using functional magnetic resonance imaging.

MATERIALS AND METHODS

Eighteen healthy right-handed volunteers were divided into three groups randomly. Each group received only one kind of acupuncture on the right LI4 (Hegu) point, which lasted 30 sec, 60 sec, or 180 sec, respectively. Fix-effect and conjunction analysis were used to compare the effects of the three kinds of acupunctures.

RESULTS

The results indicated that the stimulation of manual acupuncture with different durations could induce different effects in the central nervous system on the human brain. The longer duration of manual acupuncture might induce more significant areas.

CONCLUSIONS

The present study provided not only neuroimaging evidence for manual acupuncture, but also a useful guide for clinical applications of acupuncture. In addition, the results might be helpful to understand the relationship between the central nervous system responses and the durations of acupuncture.

Ab initio modeling of the interaction of electron beams and single-walled carbon nanotubes

Single-walled carbon nanotubes are readily observable in a scanning electron microscope, which traditional models fail to explain. We present an ab initio model to explain how the electron beam can interact with these structures despite the very small, nanoscale, interaction volume. In particular, we show how the electron beam can generate very strong secondary electron emission from the tip of a nanotube under external electric field. The approach may also be used in modeling the interaction of charged particles with nanostructures in other applications such as electron detection.

Visual attention deficits in Alzheimer's disease: an fMRI study

Cognitive and neuroscience studies indicate that attentional operations are impaired in Alzheimer's disease (AD). Our goal was to define the anatomical areas of activation associated with visual attention processing and to define deficits or changes that may occur in AD patients compared with control group. Thirteen AD patients and 13 age- and education-matched normal controls were tested in two visual search tasks (one was a conjunction task, where feature binding is required. The other was a subset task, where group stimuli is needed without feature binding) using fMRI techniques. After stereotactical normalization, voxel-by-voxel t statistics was used to compare activated brain areas between patients and control subjects. Our findings suggest that both search tasks are controlled by partially overlapping cerebral networks, including parietal, frontal and occipital-temporal cortical regions and primary visual cortex. The AD patient group showed less activation in both parietal lobes and the left frontal regions, while increased activation was found in the right frontal lobes and the right occipito-temporal cortical regions with the conjunction task. In the subset task, decreased activation in AD patients was seen in the left parietal lobe and bilateral frontal lobes, while increased activation was seen in both medial temporal lobes. In addition, for the comparison between tasks, The difference is very small for AD patients. Control group showed a higher amplitude in the right prefrontal region, temporal cortical regions and parietal lobe. These results indicate that attention deficits in AD patients may be attributed to both binding problem and grouping inefficiency.

Acupoint-specific fMRI patterns in human brain

Specific central nervous system (CNS) responses to acupuncture have recently attracted attention. It is important to understand the differences in fMRI images of the brain evoked by acupuncture at an acupoint and at a nearby "sham" point. Here, we report analyses of fMRI images of the brains of 37 healthy volunteers in response to acupuncture at Liv3 (Taichong) and LI4 (Hegu) versus their sham points. We found common activation areas in response to Liv3 or LI4 acupuncture in the middle temporal gyrus and cerebellum, along with deactivation areas in the middle frontal gyrus and inferior parietal lobule, compared with the effects of acupuncture at sham points. Acupuncture at Liv3 evoked specific activation at the postcentral gyrus, posterior cingulate, parahippocampal gyrus, BA 7, 19 and 41, but deactivation at the inferior frontal gyrus, anterior cingulate, BA 17 and 18, compared with acupuncture at its sham point. Acupuncture at LI4 evoked specific activation at the temporal pole, but deactivation at the precentral gyrus, superior temporal gyrus, pulvinar and BA 8, 9 and 45, compared with acupuncture at its sham point. These observations reveal that acupuncture at acupoints induces specific patterns of brain activity, and these patterns may relate to the therapeutic effects of acupuncture.

Lifetime of charge carriers in multiwalled nanotubes

The nature of low-energy excitations in multiwalled nanotubes (MWNTs) is investigated by means of two-color time-resolved photoemission. A careful analysis of the ballistic transport, secondary excitations, and band structure effects was employed in order to extract single electron lifetimes from the observed relaxation trend. It is demonstrated that in the vicinity of the Fermi level the energy dependence of e-e scattering times is inversely proportional to approximately the square of the excitation energy. This result provides strong evidence that electron transport in MWNTs exhibits a Fermi-liquid behavior, indicating that long-range e-e interaction along the tube vanishes due to screening.

Routes to control of H2 Coulomb explosion in few-cycle laser pulses

We have measured coincident ion pairs produced in the Coulomb explosion of H2 by 8-30 fs laser pulses at different laser intensities. We show how the Coulomb explosion of H2 can be experimentally controlled by tuning the appropriate pulse duration and laser intensity. For laser pulses less than 15 fs, we found that the rescattering-induced Coulomb explosion is dominated by first-return recollisions, while for longer pulses and at the proper laser intensity, the third return can be made to be the major one. Additionally, by choosing suitable pulse duration and laser intensity, we show H2 Coulomb explosion proceeding through three distinct processes that are simultaneously observable, each exhibiting different characteristics and revealing distinctive time information about the H2 evolution in the laser pulse.

Time-resolved photoimaging of image-potential states in carbon nanotubes

The first experimental evidence for the existence of image-potential states in carbon nanotubes is presented. The observed features constitute a new class of surface image states due to their quantized centrifugal motion. Measurements of binding energies and the temporal evolution of image state electrons were performed using femtosecond time-resolved photoemission. The associated lifetimes are found to be significantly longer than those of n=1 image state on graphite, indicating a substantial difference in electron decay dynamics between tubular and planar graphene sheets.

Effects of molecular structure on ion disintegration patterns in ionization of O2 and N2 by short laser pulses

We demonstrate that the structure of the outermost orbitals of oxygen and nitrogen can be observed in the angular distribution of coincident ion pairs generated by the double ionization of these molecules by 8 fs laser pulses. We do this by establishing that these ions emerge from well defined excited electronic states of O2+2 and N2+2 respectively and that they are produced dominantly through a process which involves electron rescattering. The angular distributions of the ions from the two targets are very different, reflecting the different structures of the outermost orbitals of the two molecules.

PET imaging of brain function while puncturing the acupoint ST36

OBJECTIVE

To explore the experimental method of obtaining position emission tonogiaphy (PET) imaging evidence of changes in cerebral function by puncturing the Stomach 36 (ST36, Zusanli) acupoint.

METHODS

Data on changes of cerebral glycometabolism were obtained from six healthy male volunteers with positron emission tomography. Visual experimental evidence, as well as statistical parametric mapping (SPM), was gathered while puncturing the ST36 (Zusanli, right leg) acupoint.

RESULTS

There was increased glycometabolism in the hypothalamus, head of the caudate nucleus, temporal lobe, the sinistral cerebellum, postcentral gyrus, and brain stem while the acupoint ST36 was being punctured.

CONCLUSIONS

Acupuncture on ST36 can lead to increase in glycometabolism in the vegetative nerve centers, which is correlated with gastric function. Visual experimental evidence of ST36 acupuncturing on functional gastrointestinal disorder was obtained in our study.

Rescattering double ionization of D2 and H2 by intense laser pulses

We have measured momentum spectra and branching ratios of charged ionic fragments emitted in the double ionization of D2 (and H2) molecules by short intense laser pulses. We find high-energy coincident D+ (and H+) ion pairs with kinetic energy releases between 8 and 19 eV which appear for linearly polarized light but are absent for circularly polarized light. The dependence on the polarization, the energy distributions of the ions, and the dependence on laser intensity of yield ratios lead us to interpret these ion pairs as due to a rescattering mechanism for the double ionization. A quantitative model is presented which accounts for the major features of the data.

The hypocholesterolemic agent LY295427 reverses suppression of sterol regulatory element-binding protein processing mediated by oxysterols

The sterol LY295427 reduces plasma cholesterol levels in animals by increasing the expression of hepatic low density lipoprotein (LDL) receptors. Here we trace the hypocholesterolemic activity of LY295427 to an ability to reverse oxysterol-mediated suppression of sterol regulatory element-binding protein (SREBP) processing. Micromolar concentrations of LY295427 induced the metabolism of LDL in oxysterol-treated cultured cells and inhibited the stimulation of cholesteryl ester synthesis mediated by oxysterols. cDNA microarray and RNA blotting experiments revealed that LY295427 increased levels of the LDL receptor mRNA and those of other SREBP target genes. The compound stimulated the accumulation of SREBPs in the nuclei of cells grown in the presence of oxysterols within 4-6 h of addition to the medium. Induction required components of the normal SREBP-processing pathway, including the SREBP cleavage-activating protein and the Site 1 protease. LY295427 overcame the suppression of SREBP processing mediated by several oxysterols but not by LDL-derived cholesterol. We conclude that LY295427 achieves a therapeutically desirable end point by an unique mechanism of action.

Multipond system: a sustainable way to control diffuse phosphorus pollution

Diffuse pollution from agricultural land is one of the main causes for lake eutrophication. Multipond systems, an ancient invention in China, are composed of many tiny ponds and ditches, scattered in agricultural fields. After a long period of research in an experimental watershed in Liuchahe, it was found that multipond systems constitute diffuse pollution control. They have a large capacity for water storage and serve to control the export of water, suspended matter, and phosphorus. Multipond systems significantly reduce runoff velocity. Sediments and phosphorus retained in the Liuchahe watershed were 14.38 x 10(6) and 7016 kg yr-1, respectively (area 691.6 ha). Irrigation provides an effective way to recycle and remove phosphorus. The use of multipond systems is a sustainable way to recycle valuable nutrients and reduce their discharge and thus pollution of downstream lakes.

Transcription factor MIZ-1 is regulated via microtubule association

A synthetic drug, T113242, activates low-density lipoprotein receptor (LDLR) transcription in the presence of sterols. T113242 also covalently binds to beta-tubulin and induces microtubule depolymerization. The myc-interacting zinc finger protein (MIZ-1) associates with microtubules, can bind directly to the LDLR promoter, and can activate LDLR transcription. MIZ-1 also binds to the promoter and activates transcription of other T113242-induced genes such as alpha(2) integrin. Soft X-ray, indirect immunofluorescence, and green fluorescent protein time-lapse microscopy reveal that MIZ-1 is largely cytoplasmic but accumulates in the nuclei of HepG2 cells upon treatment with T113242. Thus, MIZ-1 appears to be regulated by association with microtubules and may activate gene transcription in response to changes in the cytoskeleton.

Unsaturated fatty acids inhibit transcription of the sterol regulatory element-binding protein-1c (SREBP-1c) gene by antagonizing ligand-dependent activation of the LXR

Sterol regulatory element-binding protein-1c (SREBP-1c) enhances transcription of genes encoding enzymes of unsaturated fatty acid biosynthesis in liver. SREBP-1c mRNA is known to increase when cells are treated with agonists of liver X receptor (LXR), a nuclear hormone receptor, and to decrease when cells are treated with unsaturated fatty acids, the end products of SREBP-1c action. Here we show that unsaturated fatty acids lower SREBP-1c mRNA levels in part by antagonizing the actions of LXR. In cultured rat hepatoma cells, arachidonic acid and other fatty acids competitively inhibited activation of the endogenous SREBP-1c gene by an LXR ligand. Arachidonate also blocked the activation of a synthetic LXR-dependent promoter in transfected human embryonic kidney-293 cells. In vitro, arachidonate and other unsaturated fatty acids competitively blocked activation of LXR, as reflected by a fluorescence polarization assay that measures ligand-dependent binding of LXR to a peptide derived from a coactivator. These data offer a potential mechanism that partially explains the long-known ability of dietary unsaturated fatty acids to decrease the synthesis and secretion of fatty acids and triglycerides in livers of humans and other animals.

The retinoblastoma gene regulates somatic growth during mouse development

Overexpression of the retinoblastoma gene (Rb) in mice leads to the dwarf phenotype. To explore the potential mechanism of Rb effects on the somatic growth, bitransgenic mice with tetracycline-regulated Rb expression were generated, and their phenotypes were compared with those of previously established Rb mouse models. By gestational day 12.5, embryos lacking Rb and those expressing twice the regular amount of Rb are 15% larger and 10-30% smaller, respectively, compared with their wild-type littermates. The dwarf phenotype is associated with increased plasma levels of insulin-like growth factor-I (IGF-I) but not with growth hormone and glucose concentrations. Down-regulation of the Rb transgene expression results in a reduction of the IGF-I plasma concentrations to normalcy and an increase of somatic growth prenatally and postnatally. Consistent with the in vivo results, cells overexpressing Rb require higher thresholds of IGF-I to stimulate proliferation. Thus, Rb plays an integral role for mouse somatic growth and maintenance during ontogenesis, and IGF-I pathway is likely to be a target for such regulation.

Accumulation of dietary cholesterol in sitosterolemia caused by mutations in adjacent ABC transporters

In healthy individuals, acute changes in cholesterol intake produce modest changes in plasma cholesterol levels. A striking exception occurs in sitosterolemia, an autosomal recessive disorder characterized by increased intestinal absorption and decreased biliary excretion of dietary sterols, hypercholesterolemia, and premature coronary atherosclerosis. We identified seven different mutations in two adjacent, oppositely oriented genes that encode new members of the adenosine triphosphate (ATP)-binding cassette (ABC) transporter family (six mutations in ABCG8 and one in ABCG5) in nine patients with sitosterolemia. The two genes are expressed at highest levels in liver and intestine and, in mice, cholesterol feeding up-regulates expressions of both genes. These data suggest that ABCG5 and ABCG8 normally cooperate to limit intestinal absorption and to promote biliary excretion of sterols, and that mutated forms of these transporters predispose to sterol accumulation and atherosclerosis.

Regulation of mouse sterol regulatory element-binding protein-1c gene (SREBP-1c) by oxysterol receptors, LXRalpha and LXRbeta

The liver X receptors (LXRs) are members of the nuclear hormone receptor superfamily that are bound and activated by oxysterols. These receptors serve as sterol sensors to regulate the transcription of gene products that control intracellular cholesterol homeostasis through catabolism and transport. In this report, we describe a novel LXR target, the sterol regulatory element-binding protein-1c gene (SREBP-1c), which encodes a membrane-bound transcription factor of the basic helix-loop-helix-leucine zipper family. SREBP-1c expression was markedly increased in mouse tissues in an LXR-dependent manner by dietary cholesterol and synthetic agonists for both LXR and its heterodimer partner, the retinoid X receptor (RXR). Expression of the related gene products, SREBP-1a and SREBP-2, were not increased. Analysis of the mouse SREBP-1c gene promoter revealed an RXR/LXR DNA-binding site that is essential for this regulation. The transcriptional increase in SREBP-1c mRNA by RXR/LXR was accompanied by a similar increase in the level of the nuclear, active form of the SREBP-1c protein and an increase in fatty acid synthesis. Because this active form of SREBP-1c controls the transcription of genes involved in fatty acid biosynthesis, our results reveal a unique regulatory interplay between cholesterol and fatty acid metabolism.

Role of LXRs in control of lipogenesis

The discovery of oxysterols as the endogenous liver X receptor (LXR) ligands and subsequent gene targeting studies in mice provided strong evidence that LXR plays a central role in cholesterol metabolism. The identification here of a synthetic, nonsteroidal LXR-selective agonist series represented by T0314407 and T0901317 revealed a novel physiological role of LXR. Oral administration of T0901317 to mice and hamsters showed that LXR activated the coordinate expression of major fatty acid biosynthetic genes (lipogenesis) and increased plasma triglyceride and phospholipid levels in both species. Complementary studies in cell culture and animals suggested that the increase in plasma lipids occurs via LXR-mediated induction of the sterol regulatory element-binding protein 1 (SREBP-1) lipogenic program.

Regulation of absorption and ABC1-mediated efflux of cholesterol by RXR heterodimers

Several nuclear hormone receptors involved in lipid metabolism form obligate heterodimers with retinoid X receptors (RXRs) and are activated by RXR agonists such as rexinoids. Animals treated with rexinoids exhibited marked changes in cholesterol balance, including inhibition of cholesterol absorption and repressed bile acid synthesis. Studies with receptor-selective agonists revealed that oxysterol receptors (LXRs) and the bile acid receptor (FXR) are the RXR heterodimeric partners that mediate these effects by regulating expression of the reverse cholesterol transporter, ABC1, and the rate-limiting enzyme of bile acid synthesis, CYP7A1, respectively. Thus, these RXR heterodimers serve as key regulators of cholesterol homeostasis by governing reverse cholesterol transport from peripheral tissues, bile acid synthesis in liver, and cholesterol absorption in intestine.

Glutathione S-transferase metabolism of the antineoplastic pentafluorophenylsulfonamide in tissue culture and mice

The microtubule disrupting agent 2-fluoro-1-methoxy-4-pentafluorophenylsu lfonamidobenzene (T138067) binds covalently and selectively to beta-tubulin and has been shown to evade drug-efflux pumps that confer multidrug resistance to other antimitotic drugs that are used in cancer chemotherapy (Shan et al., 1999). In addition to these resistance mechanisms, eukaryotic cells have developed other protection mechanisms that involve enzymes that modify electrophilic xenobiotics. To determine whether T138067 is a substrate for such enzymatic detoxification pathways, a metabolism study was initiated. GSH conjugation was shown to play a major role in T138067 metabolism. T138067-GSH conjugates were isolated from the culture media of T138067-treated cells and the bile of mice treated i.v. with T138067. The major T138067-GSH degradation products were also isolated from these sources. 19F NMR studies of the metabolites showed that metabolic conversions occurred through substitution of the para fluorine atom in the pentafluorophenyl ring of T138067. The T138067-GSH conjugate was also isolated from T138067 incubation buffer that had been exposed to mouse, rat, dog, or human liver slices, suggesting that this mechanism is not species-specific. All three human glutathione S-transferases (alpha, mu, and pi), which are expressed in a wide variety of tissues including human tumors, were shown to metabolize T138067 effectively in vitro. The combined data show that T138067 is being metabolized, in vitro and in vivo, predominantly via a glutathione S-transferase-mediated metabolic pathway.

Prevention of intima hyperplasia by mitogen-activated protein kinase antisense oligodeoxynucleotide

AIM

To investigate the preventive effect of Ca(2+)-calmodulin dependent kinase (CCDPK) (formerly: mitogen-activated protein kinase or MAPK) antisense phosphorothioate oligodeoxynucleotide (ODN) on vascular smooth muscle cell (VSMC) proliferation in vitro and on intima hyperplasia after injury in vivo.

METHODS

Liposomal transfection was used to introduce phosphorothioate-protected 17-mer antisense CCDPK ODN directed against the initiation of translation sites of the p42 and p44 CCDPK isoforms into cultured rat VSMC to deplete CCDPK and DNA synthesis induced by endothelin-1 (ET) or platelet derived growth factor (PDGF). A 17-mer sense and a random sequence CCDPK ODN were used as controls. CCDPK protein p44 and p42 levels were measured by Western blot. DNA synthesis was measured by [3H]thymidine incorporation. In in vivo study, rat balloon angioplasty was performed by a 2F Fogarty catheter. The antisense CCDPK ODN 200 micrograms was administered to the adventitial surface of the injured carotid artery by pluronic gel 30% (w/v) solution. Two weeks after vascular injury, carotid arteries were removed and cross sections were made and stained with hematoxylin/eosin for patho-histological examination. Fluorecein isothiocynate (FITC)-labeled and phosphorothioate-protected ODN was used to detect the uptake of ODN in vitro and in vivo.

RESULTS

CCDPK antisense ODN (0.4 mumol.L-1) reduced p42/p44 protein expression and inhibited VSMC [3H]thymidine incorporation stimulated by ET and PDGF. Antisense CCDPK ODN treatment at 2 wk after injury resulted in a significant inhibition of intima hyperplasia, compared with untreated vessels.

CONCLUSION

The p42/p44-CCDPK antisense ODN inhibits in vitro stimulated rat VSMC proliferation and in vivo injured arterial intima hyperplasia.

FXR, a bile acid receptor and biological sensor

Bile acid synthesis is a major pathway for cholesterol disposal and thus represents a potential therapeutic target pathway for the treatment of hypercholesterolemia. Recently, the nuclear farnesoid X receptor (FXR) was identified as a bile acid receptor and biological sensor for the regulation of bile acid biosynthesis. FXR was shown to regulate cholesterol metabolism in two ways: (1) chenodeoxycholic acid (CDCA), a primary bile acid, binds directly to and activates FXR, which then mediates the feedback suppression by bile acids of cholesterol 7 alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid biosynthesis from cholesterol; and (2) FXR participates in the activation of intestinal bile acid binding protein (IBABP), which is involved in the enterohepatic circulation of bile acids. Thus FXR constitutes a potential therapeutic target that can be modulated to enhance the removal of cholesterol from the body.

Novel halogenated sulfonamides inhibit the growth of multidrug resistant MCF-7/ADR cancer cells

In this report, we describe the synthesis of halogenated benzenesulfonamide compounds and their ability to inhibit the growth of HeLa, MCF-7 and MCF-7/ADR tumor cells in vitro. The multidrug resistance (MDR) phenotype of certain cells does not affect their sensitivity to these compounds. These agents belong to a family of compounds previously shown to bind irreversibly to cysteine-239 of beta-tubulin. Consistent with this mechanism of action, the cytotoxicities of these compounds appear to correlate with their ability to undergo nucleophilic aromatic substitution.

CPF: an orphan nuclear receptor that regulates liver-specific expression of the human cholesterol 7alpha-hydroxylase gene

Cholesterol 7alpha-hydroxylase is the first and rate-limiting enzyme in a pathway through which cholesterol is metabolized to bile acids. The gene encoding cholesterol 7alpha-hydroxylase, CYP7A, is expressed exclusively in the liver. Overexpression of CYP7A in hamsters results in a reduction of serum cholesterol levels, suggesting that the enzyme plays a central role in cholesterol homeostasis. Here, we report the identification of a hepatic-specific transcription factor that binds to the promoter of the human CYP7A gene. We designate this factor CPF, for CYP7A promoter binding factor. Mutation of the CPF binding site within the CYP7A promoter abolished hepatic-specific expression of the gene in transient transfection assays. A cDNA encoding CPF was cloned and identified as a human homolog of the Drosophila orphan nuclear receptor fushi tarazu F1 (Ftz-F1). Cotransfection of a CPF expression plasmid and a CYP7A reporter gene resulted in specific induction of CYP7A-directed transcription. These observations suggest that CPF is a key regulator of human CYP7A gene expression in the liver.

Identification of a nuclear receptor for bile acids

Bile acids are essential for the solubilization and transport of dietary lipids and are the major products of cholesterol catabolism. Results presented here show that bile acids are physiological ligands for the farnesoid X receptor (FXR), an orphan nuclear receptor. When bound to bile acids, FXR repressed transcription of the gene encoding cholesterol 7alpha-hydroxylase, which is the rate-limiting enzyme in bile acid synthesis, and activated the gene encoding intestinal bile acid-binding protein, which is a candidate bile acid transporter. These results demonstrate a mechanism by which bile acids transcriptionally regulate their biosynthesis and enterohepatic transport.

Selective, covalent modification of beta-tubulin residue Cys-239 by T138067, an antitumor agent with in vivo efficacy against multidrug-resistant tumors

Microtubules are linear polymers of alpha- and beta-tubulin heterodimers and are the major constituents of mitotic spindles, which are essential for the separation of chromosomes during mitosis. Here we describe a synthetic compound, 2-fluoro-1-methoxy-4-pentafluorophenylsulfonamidobenzene (T138067), which covalently and selectively modifies the beta1, beta2, and beta4 isotypes of beta-tubulin at a conserved cysteine residue, thereby disrupting microtubule polymerization. Cells exposed to T138067 become altered in shape, indicating a collapse of the cytoskeleton, and show an increase in chromosomal ploidy. Subsequently, these cells undergo apoptosis. Furthermore, T138067 exhibits cytotoxicity against tumor cell lines that exhibit substantial resistance to vinblastine, paclitaxel, doxorubicin, and actinomycin D. T138067 is also equally efficacious in inhibiting the growth of sensitive and multidrug-resistant human tumor xenografts in athymic nude mice. These observations suggest that T138067 may be clinically useful for the treatment of multidrug-resistant tumors.

Novel antineoplastic agents with efficacy against multidrug resistant tumor cells

A novel series of pentafluorobenzenesulfonamides has been shown to inhibit the growth of a variety of human tumor cell lines. Among the cell types against which these agents were evaluated were the multidrug resistant (MDR) cell lines MCF-7/ADR and P388/ADR. The cytotoxic activity of members of this series of compounds was not affected by the multidrug resistant pump in MCF-7/ADR or P388/ADR cells.

Five monoclonal antibodies against glycophorin A of human erythrocyte recognize glycoprotein of bovine erythrocyte

To study heterophile blood antigens on erythrocytes between human and experimental or domestic animals, we have produced 295 monoclonal antibodies (MAbs) to human erythrocyte membrane protein. According to the affinity, reactivity, and titre of the MAbs, we selected 40 clones to study the heterophile blood antigens between human and bovine, chicken, guinea pig, horse, rabbit, sheep, and swine. Five MAbs commonly reacted with human type A, type B, and type O erythrocytes and reacted with bovine erythrocytes as well but did not react with erythrocytes from other species. Other MAbs did not react with erythrocytes from all the tested animals. These five MAbs reacted with the same erythrocyte membrane protein, 90 KD glycophorin A (GPA) of human or 200 KD major glycoprotein and other two components of bovine by immunoblotting and GPA competitive inhibition assay. Furthermore, by enzyme treatment and monosaccharide competitive inhibition assay, it was confirmed that these five MAbs recognized antigen epitope of glycosylation free amino acid portion but not glycosylation portion of GPA of erythrocyte membrane.

Ultrafast x-ray diffraction using a streak-camera detector in averaging mode

We demonstrate an apparatus for measuring time-dependent x-ray diffraction. X-ray pulses from a synchrotron are diffracted by a pair of Si(111) crystals and detected with an x-ray streak camera that has single-shot resolution of better than 1 ps. The streak camera is driven by a photoconductive switch, which is triggered by 100-fs laser pulses at a repetition rate of 1 kHz. The laser and the streak camera are synchronized with the synchrotron pulses. In the averaging mode, trigger jitter results in 2-ps temporal resolution. We measured the duration of 5-keV pulses from the Advanced Light Source synchrotron to be 70ps.

The molecular basis of E2F-1/DP-1-induced S-phase entry and apoptosis

The transcription factor E2F plays a critical role in the G1 to S transition. E2F is a heterodimer formed by members of the E2F and DP families of DNA-binding proteins. Ectopic expression of E2F-1, the first member of the E2F family identified, is sufficient to cause quiescent cells to enter S phase. Thus, the biological significance of the interaction of E2F-1 with its DP protein partner, DP-1, was unclear. Here, we report on the role of DP-1 in the mediation of E2F-induced S-phase entry and apoptosis. Cells inducible for DP-1, E2F-1, or both were established and characterized. Ectopic expression of DP-1 alone fails to promote cell cycle entry, even when the potent transactivation domain of human papillomavirus-VP16 is fused to the DNA-binding domain of DP-1. In contrast, coexpression of DP-1 and E2F-1 results in greater loss of G1 regulation and significantly more apoptosis than does E2F-1 alone. Using clones co-inducible for DP-1 and E2F-1, expression of potential target genes of E2F activity that may account for its ability to induce S-phase entry was also examined. Induction of E2F-1/DP-1 resulted in increased expression and activity of cyclins A and E, as well as CDK2, prior to S-phase entry. Cyclin D and CDK4, however, were not induced. Phosphorylation of the retinoblastoma protein is also increased following induction of E2F-1/DP-1, suggesting that E2F can feed-back on the retinoblastoma protein, presumably through activation of cyclin A- and/or E-associated kinase activity.

Identification of the promoter of the mouse obese gene

Primer extension and RACE (rapid amplification of cDNA ends) assays were used to identify and sequence the 5' terminus of mouse ob mRNA. This sequence was used to obtain a recombinant bacteriophage containing the first exon of the encoding gene. DNA sequence analysis of the region immediately upstream of the first exon of the mouse ob gene revealed DNA sequences corresponding to presumptive cis-regulatory elements. A canonical TATA box was observed 30-34 base pairs upstream from the start site of transcription and a putative binding site for members of the C/EBP family of transcription factors was identified immediately upstream from the TATA box. Nuclear extracts prepared from primary adipocytes contained a DNA binding activity capable of avid and specific interaction with the putative C/EBP response element; antibodies to C/EBP alpha neutralized the DNA binding activity present in adipocyte nuclear extracts. When linked to a firefly luciferase reporter and transfected into primary adipocytes, the presumptive promoter of the mouse ob gene facilitated luciferase expression. When transfected into HepG2 cells, which lack C/EBP alpha, the mouse ob promoter was only weakly active. Supplementation of C/EBP alpha by cotransfection with a C/EBP alpha expression vector markedly stimulated luciferase expression. Finally, an ob promoter variant mutated at the C/EBP response element was inactive in both primary adipocytes and HepG2 cells. These observations provide evidence for identification of a functional promoter capable of directing expression of the mouse ob gene.

Disruption of RB/E2F-1 interaction by single point mutations in E2F-1 enhances S-phase entry and apoptosis

The retinoblastoma protein (RB) has been proposed to function as a negative regulator of cell proliferation by complexing with cellular proteins such as the transcription factor E2F. To study the biological consequences of the RB/E2F-1 interaction, point mutants of E2F-1 which fail to bind to RB were isolated by using the yeast two-hybrid system. Sequence analysis revealed that within the minimal 18-amino acid peptide of E2F-1 required for RB binding, five residues, Tyr (position 411), Glu (419), and Asp-Leu-Phe (423-425), are critical. These amino acids are conserved among the known E2F family members. While mutation of any of these five amino acids abolished binding to RB, all mutants retained their full transactivation potential. Expression of mutated E2F-1, when compared with that of wild-type, significantly accelerated entry into S phase and subsequent apoptosis. These results provide direct genetic evidence for the biological significance of the RB/E2F interaction and strongly suggest that the interplay between RB and E2F is critical for proper cell cycle progression.

Characterization of a novel 350-kilodalton nuclear phosphoprotein that is specifically involved in mitotic-phase progression

A gene assigned to human chromosome 1q32-41 encodes a novel protein of 3,113 amino acids containing an internal tandem repeat of 177 amino acids. The protein, which we have named "mitosin," was identified by direct binding to purified retinoblastoma protein in vitro with a region distantly related to the retinoblastoma protein-binding site of E2F-1. Mitosin is expressed throughout S, G2, and M phases of the cell cycle but is absent in G1. Its localization is dramatically reorganized from a rather homogeneous nuclear distribution in S phase to paired dots at the kinetochore/centromere region, to the spindle apparatus, and then to the midbody during M-phase progression. This spatial reorganization coincides closely with the temporal phosphorylation patterns of mitosin. Overexpression of N-terminally truncated mutants blocks cell cycle progression mainly at G2/M. These results suggest that mitosin may play an important role in mitotic-phase progression.

Deregulated expression of E2F-1 induces S-phase entry and leads to apoptosis

E2F-1, the first gene product identified among a family of E2F transcription factors, is thought to play a critical role in G1/S progression of the cell cycle. Transcriptional activities of E2F are modulated during the cell cycle, mainly by the formation of complexes between E2F and several key regulators of cell cycle such as the retinoblastoma protein and related proteins. To further understand the roles of E2F in the cell cycle progression, we have overexpressed exogenous E2F-1 by using a tetracycline-controlled expression system. We have found that the induced expression of E2F-1 in Rat-2 fibroblasts promotes S-phase entry and subsequently leads to apoptosis. The apoptosis occurs in an E2F-1 dose-dependent manner. Cells resistant to the induction of apoptosis have lost the ability to express exogenous E2F-1. Cells growing in low serum are more sensitive to the E2F-1-mediated cell death. Overexpression of E2F-1 mutants that impair DNA binding or transactivation does not alter cell cycle progression or induce apoptosis. These results define a novel pathway to apoptosis and demonstrate that premature S-phase entry is associated with apoptotic cell death.

The retinoblastoma gene product is a cell cycle-dependent, nuclear matrix-associated protein

The retinoblastoma gene product (Rb) has been established as a tumor suppressor and cell cycle regulator, although its mechanism of action remains obscure. The observations that several Rb-binding viral oncoproteins all associate with the nuclear matrix suggest that these interactions may occur on this structure. To determine whether Rb itself is a component of the matrix, we extracted synchronized cultured cells to isolate matrix proteins while preserving nuclear architecture. Immunoblot and immunolabeling data show that a significant portion of hypophosphorylated Rb associates with the matrix only during early G1. Mutant Rb in tumor cells did not associate with the matrix, whereas Rb-reconstituted cells contained abundant matrix-bound Rb. Rb is distributed widely throughout the matrix, particularly concentrated at the nuclear periphery and in nucleolar remnants. Core filaments of the matrix contained no detectable Rb. Our screening of expression libraries for potential Rb-associated proteins has identified several that are part of the matrix. Specifically, the peripheral matrix proteins lamin A and C bound Rb in vitro. We therefore suggest that Rb interactions with the nuclear matrix may be important for its ability to regulate cell cycle progression.

The transcription factor E2F-1 mediates the autoregulation of RB gene expression

The retinoblastoma (RB) gene is the prototype tumor suppressor gene. Mutations in this gene are often associated with the occurrence of various tumors. Several mutations have been found in the promoter region of the gene, suggesting that inappropriate transcriptional regulation of the RB gene contributes to tumorigenesis. Sequence analysis of the RB promoter has revealed a potential E2F recognition site within a region critical for RB gene transcription. By using the cloned E2F-1 gene, here we report that (i) RB expression is negatively regulated by its own gene product, (ii) E2F-1 binds specifically to an E2F recognition sequence in the RB promoter and transactivates the RB promoter, (iii) overexpression of RB suppresses E2F-1-mediated stimulation of RB promoter activity, and (iv) the expression of the RB gene is paralleled by the expression of the E2F-1 gene during cell cycle progression. These results demonstrate that expression of RB is negatively autoregulated through E2F-1.